-■ r *. (3 /£ brary, free of any Charge. 2.— Persons who are not members df the above-named Society, may have use of the Library, by paying a Subscription of Two Pi:nce pee Week, or Eigiit Shillings per Annum, in advance. 3.— No person is allowed to retain a Book longer than a Fortnight, or to have more than One Book at the same time. A Fine of Two Pence per Week will be charged for any infrac- tion of this Rule. 4. — Subscribers are liable for the value of any Book lost or injured while in their posses- sion. 5.— Books of Reference, Maps, Dictionaries, Encyclopaedias, &c., &c, are not leht out. G. — The Sub-Librarian attends at the Li- brary each day from Twelve to Eight o'Clock, p.m., to receive Subscriptions, deliver and re- ceive Books, &c. Wn-LIAM-STREET, May 25th, 1859. i ) I EXPERIMENTAL RESEARCHES CONCERNING THE PHILOSOPHY OF PERMANENT COLOURS; AND THE BEST MEANS OF PRODUCING THEM, BY ^ DYEING, CALICO PRINTING, $c. BY EDWARD BANCROFT, M. D. FELLOW OF THE ROYAL SOCIETY OF LONDON, AND OF THE AMERICAN ACADEMY OF ARTS AND SCIENCES, OF THE STATE OF MASSACHUSETTS BAY. " Cct art ( INTRODUCTION. therefore, employed. But to obviate this inter- ference, the pope pretended to devote the reve- nue produced by his alum works to the defence of Christianity against the Turks, and menaced ail who should act so unchristianly, as to pur- chase, or procure, alum from these infidels, with sxcorilmumcation ; which prohibitions were re- newed by several of his successors. It appears from Biringocci's Pyrotechn, p. 32, that the first alum work established out of Italy, subsequently to the discovery of those of Tolfa, was that of Ahuacaron, near Carthagena, in Spain ; whence, as is stated in Guicardini's description of the Netherlands, large quantities of alum were brought to Antwerp, in the early part of the 16th century. In England the first alum work was that of Gisborough, in Yorkshire, begun near the end of Queen Elizabeth's reign, upon lands belonging to Sir Thomas Chaloner, who secretly procured workmen from the alum works at Tolfa, no person in England then knowing how to produce it. This seduction of his workmen so enraged the pope, as we are told by Pennant, in his Tour to Scotland, that his holiness endeavoured to frighten and recall them, by curses, or anaihe- mas, in the very form left us by Ernulphus. The intimate and important connection of the history of alum with that of dyeing, has in- duced me to state these facts, which I have chiefly derived from Beckman's first volume; INTRODUCTION, xxxvu though I have not thought it right to adopt some of his conclusions on this subject. To discover by retrospection all the ways and means by which an art like that of dyeing has been improved from its earliest and most aiT-ple beginnings, in different parts of the world, must now be impossible j because, among some nations, it, undoubtedly, would have been considerably advanced, by fortunate accidents and instructive observations, long before they had learned to write histories and record facts) and, indeed, almost all the progress which had been made in dyeing, until within a few years, must have resulted from such causes ; depending, as it does, for its principles upon chemistry, which was by much too defective to afford any considerable assistance, either to practical dyers, or speculative men, who might have wished to study and improve the art ; and, therefore, it happened, as might have been expected, that the practice of dyeing had, by the fortuitous discoveries of great numbers of indi- viduals employed in it, been carried so far before the theory ', that the latter was as little capable of explaining, as it had been of suggesting the most beneficial effects produced by it ; and this, pro- bably, was at least one reason why dyeing was so much neglected among the philosophers of Greece and Rome, though they highly esteemed the arts of painting, sculpture, &c. Notwithstanding the great importance of alum, in dyeing, it is not probable that mankind, with XxXviu INTRODUCTION. their natural disposition to admire gaudy colours, and seek personal distinctions, should have de- layed the application even of adjective dyeing matters, to their clothing, until they had become acquainted with alum and its effects, in raising and fixing the colours afforded by these matters. Such an acquaintance would not, in the ordinary course of events, be acquired, until some pro- gress had been made in civilization ;* and there are many facts to prove that, in much ruder states of society, men have attempted to dye their cloth- ing ;f and as these attempts would have proved more successful upon 'wool than upon linen, or cotton, by reason of the greater affinity of the former to some adjective colouring matters, (as * Clavigero, in his history of Mexico, pretends that the Mexi- cans used the earth of alum to produce certain colours : that, after grinding and dissolving the aluminous earih, which they called tlalzocotl, they boiled it in earthen vessels, and then, by distillation, extracted the alum pure, white and transparent ; and that, before they hardened it entirely, they divided it in pieces to sell in the market. To a chemical reader this will sufficiently discover the ignorance of the historian in regard to the effect of distillation, Sec. Wbgl foundation ttus account may have had in other respects I know not.' f Of the nature of these attempts, and the value of some at Iea# of the colours produced by them, we may judge, by the mention which Pliny has made of a purple dyed for the clothing of inferior people among the Gauls, from " vacci- nia ;" by which either the ripe privet, or the whortle berries, are supposed to have been meant. See Lib. xvi. c. 18. He also mentions violets as being used to produce a purple. INTRODUCTION. XXXIX lately noticed) we may conclude, that in climates which required clothes of wool, the dyeing of these would have been practised much earlier than that of linen or cotton.* And, accordingly, • Uncivilized nations appear, in some instances at least, to have found means to increase this affinity, particularly by the use of vegetable acids. The savage tribes of North America, had long been accustomed to dye certain animal substances, such as hair, feathers, and porcupine quills of bright red and yellow colours, whilst they were wholly unacquainted with the use of alum ; and having been informed, that the red, so dyed, was produced from the galium tinctorum, and the acid berries of the scarlet sumach, lately mentioned, I made trial of them upon broad cloth without alum, and produced a red colour inclining to the orange, of considerable brightness, which, being exposed with a red less inclining to the orange, which I had dyed also from the roots of galium tinctorum only j but upon broad cloth, prepared as usual with alum and tartar, I found, at the end of two months, that, though the latter had suffered least, the other with sumach berries was much better and more lasting than I had supposed it possible to produce without some basis. I have since been informed, that the acid juice of the crab apple is sometimes employed by the tribes in North America for the same purpose j and that Pro- fessor Woodhouse, of Philadelphia, supposes himself to have discovered alumine in the very acerb fruit of the diospyros vir- giniana, or persimmon tree, which, if this supposition be well founded, may be expected to produce still better effects as a mordant for dyeing, than either of the acids before mentioned ; unless the latter, assome have supposed, should also contain alum. Indeed, Loureiro (torn. i. p. 315.) has described a tree, under the name of decadia aluminosa, of which he says the bark, and more especially the dried leaves, are in great use among xl INTRODUCTION. Pliny mentions dyed linen as having been seen for the first time, in the fleet with which Alex- ander the Great had navigated the river Indus, when his captains, in skirmishing with the In- dians upon its banks, to their astonishment sud- denly changed the ensigns of their vessels, and displayed flags of various colours wavering in the wind.f It must, however, be confessed that, according to Piiny's account, the dyeing even of woollen clothes had, at that time, made but little progress, at least in regard to the finer colours ; for, in the eighth chapter of his twenty first book, after declaiming against the luxury of his cotem- porarics, in wearing clothes dyed of colours which emulated those of the finest natural [flowers, he ob- serves, that none of these flowery colours (" {lo- res") were in use during the life of Alexander the Great ; though, says he, nobody doubts of their the dyers of Cocbinchma, to exalt and Jlx their colours. •* Magni usus sunt infectoribus indigenis In tingendis telis qua- mm colores decocto illorum nitide exaltantur & jinnantur" This statement, joined to the specific name of ulumineuosa, appears to indicate that the bark and leaves of this tree either contain alumine, or are thought capable of answering the pur- poses of alum as a mordant. * ' f Tentatum est tingi ilnum, quoque & vestium insaniam accipere, in Alexandri Magni primum classibus, Indo auine navigantis, cum duces ejus et prefect! certamine quodam variassent insignia navium : stupueruntque littora, flatu versj poloria implente." INTRODUCTION. xli bavins; been borrowed bv the Romans from the Greeks ; for how else, he asks, should the names which they still retain in Italy, have been all Grecian, " a Graecis tamen repertos quis dubitet ; non aliter Italia usurpante nomina illorum ?" Probably, the companions of Alexander, when he invaded Persia and India, became acquainted with the rich dyes of those countries ; and after- wards made some, at least, of them known to the Greeks, among whom, as well as among the Ro- mans, the wearing of undyed cloths, (which Pliny has denominated " panni nativi coloiis") had been immemorially practised by the great mass of peo- ple. * We are not, however, to understand that dyed clothes were not in much higher estimation than the undyed, as soon as they were made known, for this, undoubtedly, was the fact ; but they were too costly to be used by any but the rich and great, or for the service of religion, or upon extraordinary occasions. See Exodus, chapters 26, 28, 33, and 39. See also Plutarch, de Iside and Osiride. c. 78, where he tells us, that the robes or sacred vestments of Isis, were of various colours ; but those of Osiris were of one bright co- lour. Juno, Venus, and Proserpine, were by the * As these untlycd clothes often wanted cleaning, this opera- tion gave employment to a description of people called Fulloues, who were properly scourers, though the clothes would naturally be thickened or fulled, in some degree, whilst in their hands. ■siii INTRODUCTION. ancient poets commonly represented as being robed k in purple ; and we are told, in the S7th chapter of Genesis, that Jacob " loved Joseph more than all his children, because he was the son of his old age ; and he made him a coat of colours .-" a dis- tinction which caused Joseph to be hated by his brothers ; and afterwards to be sold by them, and carried into Egypt. Of the substantive colours known in Greece, and at Rome, two, (highly deserving of our no- tice) were the celebrated purple obtained from the murex and buccinum, and the blue procured from indigoferous plants, particularly the woad, (glastum or isatis tinctoria) : of these, and of their connection with the history of dyeing, most ample and interesting accounts will be found, in the 4th and 6th chapters of the first part of this work. Another plant, by the Romans called Jul us, and which appears to have been no other than that species of lichen which is now called orchall, was in such general use among the latter, for dyeing a beautiful, though not durable purple, that the name of fucus, came at length to be often used as signifying generally a dye. Of this also a sufficient account will be found at p. 291 of this volume. In regard to the adjective colouring matters for which alum or aluminous earths and other mor- dants were employed by the ancients, I must ob- serve* that it seems difficult to give a complete INTRODUCTION. xliii account of them : though we have reason to con- clude, that the kermes(or coccus illicis) and madder (rubia) were by much the most important : of these also, and of their connection with the his- tory of dyeing, sufficient accounts will be found in their proper places. To these may be acjded the roots of anchusa tinctoria, or alkanet, the ge^ nista tinctoria, or dyer's broom, (mentioned by Pliny, xvi. c. 18.) gall-nuts, pomegranate-peels, alder bark, the rinds of walnuts, the bark of the walnut tree, and the pods of the Egyptian acacia ; but of the particular methods in which these were employed, or of the basis or mordants used with them, no information worthy of being here par- ticularly noticed has been transmitted to us, either by Greek or Latin writers. And, indeed, almost all the knowledge which the Greeks and Romans had obtained from others, or acquired by their own industry, on this subject, appears to have been lost about the fifth century, when, as M. Ber- thollet has observed, scarce any traces of science or humanity were left in the western empire. A few sparks of the former did, indeed, remain in Italy, where they were in some degree rekindled, by occasional accessions of knowledge,and of Greek artists obtained from the East, in consequence of the crusades ; and also, from the various importations made by the Venetians, of oriental productions and manufactures ; which, by afford- ing new materials, and new objects of imi« ■ -». xiir INTRODUCTION. tation, assisted in exciting and directing that in- dustry which had so long been dormant in the west of Europe. Italy may, therefore, be considered as the cradle in which a feeble remnant of the knowledge of dyeing, as exercised by the Greeks and Romans, was nourished and invigorated, so as, with the nexv dyeing drugs since obtained from India and America, (which will be hereafter noticed) and with the various subsequent acquisitions of che- mical and other knowledge, to have attained a state of improvement, greatly exceeding all for- mer expectation. From Italy some knowledge of dyeing, limited as it was, spread itself gradually to France, Spain, and Flanders, whence King Edward the Third of England, procured dyers ; and in 1472, a com- pany of these artists was incorporated in Lon- don. The Germans, as Rischoff informs us, were slow in acquiring and practising the art of dyeing; excepting only that of black, which was their dress or gala colour ; and excepting browns, which were generally wore by the monks, and the com- mon people. In France a division was established at a very early period, between the dyers of lasting colours, who were denominated " teinturiers en ban teint" and the dyers of fugitive colours, or those " en petit teint ;*' and the former were prohibited from INTRODUCTION. xlv using, or having in their possession, the dyeing drugs employed by the latter. A similar distinc- tion was also established in Italy, as BischofF states, on the authority of a French ordinance of Nov. 17th, 1383. The first Italian account of the processes used in dyeing, as BischofF, and after him Bcrthollet, have "informed us, was published at Venice in 1429,** under the title of " Mariegola delV Arte del Ten- tori,'* of which a second edition appeared in 1510. But the imperfections of this work, induced John Ventura Rosetta, overseer of the Arsenal at Ve- nice, to undertake a work less defective ; and the better to execute his undertaking, he travelled over different parts of Italy, and some other countries, to acquire information ; from which he composed, and in 1548 published, under the assumed name of Plictko, a collection of descrip- tions of the operations of dyeing, as then prac- tised, which Bischoff considers as the foundation and principal cause of many subsequent improve- ments in this art :* though Hellot has mentioned it as deserving but little notice. Of the important changes, and rapid advance- * The title of this work, was " Plictho dell' Arte dc tentori chc insegna tenger panni, tele, banbasi, e sede si per 1'arle msgiore, come per la commune. Vinezia 1448, 4to." Or Plictho's Art of Dyeing, which teaches how to dye cloth, linen, cotton and silk, of durable, as well as false, or ordinary colours, &c. !\i INTRODUCTION. ment, which were produced in dyeing after, and by the discovery of new and valuable colouring matters, and also of new bases or mordants, (par- ticularly that of tin) sufficient accounts are given in the course of this work, and to these I must refer, to avoid improper repetitions. The first or earliest book, which I have been able to discover in the English language, relating in any considerable degree to the art of dyeing, is a thin and small 4to. volume, (now before me) in black letter, intitled " A profitable Booke, declaring divers approved remedies to take out spots and stains, in silkes, velvets, linnen, and woollen clothes j with divers colours how to die velvets, and silkes, linnen, and woollen, fustian, and thread: also to dress leather and to colour felles." "Taken out of Dutch, and Englished by L. M. Imprinted at London, by Thomas Purfoot, dwel- ling within the New Rents in S. Nicholas Shambles, 1605." The instructions contained in this last volume, relate principally to the use of indigo, (which is Berthollet has remarked, that there is no mention in thia work, of either cochineal or indigo ; whence he infers, that neither of these important drugs had then been employed for dyeing in Italy; an inference which, though probably just, seems extraordinary, considering the facts which will be found in the fifth chapterof the first part, and the third chapter of the second part of this work. INTRODUCTION. xlvt called flora or floray), vvoad, madder, (particu- larly the crap) Brasil wood, weld, safflower, gall- nuts and alder bark ; once or twice kermes and lac are mentioned ; but not cochineal. These in- structions seem to be founded chiefly upon the practices of the dyers in Flanders, where the art at that time was making considerable progress; but as black was the colour in most general use, the receipts, if I may so call them, for producing it, are in number equal to almost all the others. After this, nothing seems to have been done in this country to inform or assist practical dyers, until the year 1662, when the Royal Society, then re- cently formed, at their meeting on the 30th of April, desired Mr. Haak to translate into the Eng- lish language the work which, more than half a century before, had been published in Italy, under the name of Plictho ; (though this has never been done) and, on the same day, Sir William Petty, one of its earliest and most active members, in consequence of a previous request from the Society, brought in " An Apparatus to the His- tory of the Common Practices of Dyeing," which was afterwards printed in Dr. Spratt's History of the Royal Society, and seems to have been the first original, though summary account published in the English language, of the means and opera- tions used by dyers. Nearly two years afterwards, viz. March 30, 1664, the Hon. Robert Boyle presented t© *lviii INTRODUCTION. the Royal Society his " Experiments and Consi- derations, touching Colours ;" and, on the 10th of August following, it was ordered by the So- ciety, " that the way of 'fixing colours should be recommended to Mr. Howard, Mr. Boyle, and Dr. Merritt." These, and especially the two first, were among the most distinguished mem- bers of the Society ; but it does not appear that they were able to do any thing deserving of notice, in consequence of this recommendation. How- ever, at a meeting of the Society on the 1 1th No- vember, 1669, that very ingenious, active, and useful member, " Mr. Hooke, produced a piece " of calico, stained after the way contrived by " himself, which he was desired to prosecute in " other colours, besides those that appeared in " this piece," (Birch's History of the Royal Society, vol. ii. p. 40 i.) And, accordingly, on the Qf.h of the following month, " Mr. Hooke M produced another specimen of staining with " yellow, red, green, blue, and purple colours, "• which, he said, would endure washing with " warm water and soap." But from this time it docs not appear that any thing considerable was done, for nearly the space of a century, by men of science in this kingdom, towards im- proving the arts of dyeing and calico printing ; they being, probably, discouraged by the difficulties which, from the very imperfect state of chemical knowledge, must have occurred, in every attempt INTRODUCTIONS xlix to improve upon what the dyers were able toper- form, without any principle or theory. In France, however, that great minister, Colbert, anxious to extend the commerce and manufac- tures of his country, turned his attention particu- larly to the art of dyeing, with a view to amend, as well as to obviate frauds in the practice ; and calling to his assistance M. D'Albo, a set of regular tions and directions were prepared and published at Paris, first in 1669, and afterwards in 1762, under the title of " Instruction generate pour la " Teinture des Laines et Manufactures de Laine " de toutes Nuances, et pour la Culture des " Drogues ou Ingredients qu'on emploie." This, however, was not intended merely to inform, but, as a legislative act, to control the dyers in their operations. It continued the former division of them into two classes ; the one, dyers " en grand," who were confined to the colours deemed lasting, while the dyers " en petit feint" were allowed only to give those which were considered as fugi-r tive ; the drugs to be employed in each branch being also particularly specified ; and the dyers in each prohibited from using, or having in their possession, any of the drugs allotted to the other, Such restraints, though intended to prevent frauds, would have operated as checks upon future im- provements, if the government had not, at the same time, encouraged useful discoveries in this art, first, by offering particular rewards, and after- d INTRODUCTION. wards, by appointing those eminent chemists, Dufay, Hellot, Macquer, and Berthollet, in succes- sion, to superintend officially, the practice of dye- ing, in its several departments, and to cultivate those branches of chemical and other sciences, which were connected with the principles, or capable of amending the theory, of that art ; and, considering the eminent benefits which have re- Suited from the labours of these men, there is cause to regret the want of such an appointment in this great manufacturing and ccmimercial na- tion. With Dufay's assistance, M.Colbert's "Instruc- tion" was amended, or rather superseded by a new one, published under the administration of M. D'Orry, in 1 737. He (Dufay) appears to have been the first who entertained just concep- tions of one of the causes of the adhesion of co- louring matters to stuffs when dyed ; I mean that which depends on an affinity or attraction sub- sisting between such matters and the fibres or substance of the dyed stuffs. He clearly per- ceived that without this, cloth, while in the dye- ing vessel, could oniy acquire a degree of colour equal to that of the dyeing liquor, by an equal participation of the colouring matter dissolved therein ; whereas, in fact, the cloth is often seen to exhaust, by attracting to itself all the tingent particles of the dyeing liquor, so as to leave it as colourless as water. He also noticed the djf» INTRODUCTION. U ference in the degrees of attraction, which dif- ferent substances, as wool and cotton, exert upon the same colouring matters ; and which he found so great, that a skein of each having been in an equal degree subjected to the means and opera- tions commonly employed for dyeing scarlet, the woollen yarn was found to be fully and perma- nently dyed of that colour, while the cotton re- tained all its former whiteness.'' He appears, however, to have had ne conception of the other and more important cause of the permanency of adjective colours, I mean that which arises from the interposition of a suitable basis, possessing a particular attraction, both for the colouring matter and for the dyed substance ; and thereby acting as a bond of union between them : nor did his successor, Hellot, ever approach nearer to the truth on this subject. He, (Hellot,) indeed, published an excellent practical treatise on the art of dyeing wool and woollen cloths, in which the several processes were very accurately described : but in reasoning upon the facts stated therein, he adopted, and suffered himself to be grossly mis- led by, a frivolous hypothesis, devoid of the least foundation in truth. He fancied that he could discover, in every dyeing process, some means * Observations Physiques surle Melange de quelques Cou- leurs dans la Teintuve, Memoires de l'Academie Royale, &c. J 73;. ill lii INTRODUCTION. by which sulphate of potash (then called vitrio- lated tartar) might be formed ; and I his neutral salt not being readily soluble by cold water, nor by air or light, he conceived the whole art of dyeing to consist in first dilating the pores of the substance to be dyed, so as to procure a copious admission of colouring matter, divided by a suit- able preparation into atoms, and then wedging or fastening these atoms within the pores of the dyed substance, by the small particles or crystals of this difficultly soluble neutral salt. Upon this mechanical hypothesis, he supposed that alum became useful in dyeing, not by the pure clay or alumine which it contains, and which alone con- tributes to fix any colouring matter, but by fur- nishing (and only by furnishing) sulphuric or. vi- triolic acid, to assist in forming the sulphate of potash, which was to perform this important function of wedging or fastening the colouring atoms; though, if he had brought this visionary hypothesis to the test of experiment, as might have been easily done, he would have found, not only that no sulphate of potash existed, in many of the cases where he supposed it to produce such important effects, but also that, even if intention- ally formed and employed for this purpose, it possessed no power whatever of fixing any co- louring matter yet known. But though nothing could be more groundless than this, theory, the learned in all countries appear to have been satis- INTRODUCTION. liii fied with it for a considerable length of time, it being always less troublesome to believe than to make experiments. The late celebrated Mac- quer, in a Memoir, printed among those of the Royal Academy of Sciences for 1749, mention- ing Hellot and his hypothesis, says, " ce savant " chymiste est le premier qui ait porte le flambeau " de la physique, dans Tart obscur de la teinture, " & qui ait rassemble et mis en ordre, suivant les " principles d'une theorie ingenieuse, les pheno- " menes et les operations bizarres de cet art : " il a mis les chymistes a portee de voir clair, dans " ce cahos tenebreux." And afterwards, in the preface to his Treatise on dyeing Silk, published in 1763, he makes this observation, " ce seroit " ici le lieu d'expliquer la maniere dont les mor- *' dants agissent dans la teinture, et de develop- " per la cause du bon -et du faux teint ; mais ces " objets ont ete traites avec tant de segacite par " M. Hellot, que je crois devoir y renvoyer le lec- teur ;" and even so lately as the year 1766, in an eulogium pronounced upon Helio f , in the Royal Academy of Sciences, ar.d published with the Memoires for that year ; the Secretary, after ex- plaining Hellot's hypothesis, says, " a i'aide de " cette theorie si iumineuse. on ne sera ;>!us troinpe " dans la pratique de cet art, que iors qu'on vou- dra bien retre." Before this time, viz. 1748, Scheffer published a small work on dyeing, which Bergman after- Uv INTRODUCTION. wards thought worthy of being republished, with notes written by himself. It related in a great degree to the application, for the benefit of the Swedish* manufactures, of the indigenous dye- ing plants of that kingdom ; in search of which, Linnaeus afterwards undertook his Iter Gothlan- dicum. Scheffer was thought to have made dis- coveries of considerable importance in dyeing, but not having been published, most of them were lost, as Bergman informs us. Mr. Henry, of Manchester, has observed, that Mr, Kcir, the ingenious translator of " Macquer's " Chemical Dictionary, appears to have been the F* first who suspected that (in dyeing) the earth " of alum was precipitated, and in this form " attached to the material prepared or dyed;" and this idea, having being published, was adopted by Mr. Macquer, and farther extended in the last edition of his " Dictionnaire de Chymie " at the article " Teinture," where he seems to have form- ed just conceptions of the nature and uses of alum, and of different metallic solutions, as mor- dants, in dyeing.* This edition was published * Berthollet considers Bergman, as being the first who as- cribed the fixing of colours, by dyeing, to paiticular affinities $ and I cannot now readily ascertain dates so accurately as to decide whether he did this previously to Mr. Keir's publication of the translation of Macquer's Dictionary. Perhaps it may be allowable for me to observe, that, in INTRODUCTION. lv in the year 177?, and Mr. Masquer soon after announced a design of writing a general treatise on the art of dyeing, which his death, however, frustrated. Sometime after Mr. Macquer's de- cease, Mr. Henry favoured the public with a very interesting paper, (in the third volume of the Memoirs of the Manchester Society,) " On the " Nature of Wool, Silk, and Cotton, as Objects " of the Art of Dyeing ; on the various . Prepa- " rations and Mordants requisite for these dif- " ferent Substances; and on the Nature and " Properties of Colouring Matter, &c." A pa- per replete with useful information and ingenious ideas, (particularly respecting the causes of the durability of what is called the Turkey red,) and which deservedly reflects great credit on the au- thor's talents and acquirements. And in the year 1791, that most excellent chemist, M. Ber- thollet, who had been appointed by the govern* ment of France to succeed Mr. Macquer in super- intending the arts connected with chemistry, and particularly dyeing, published a work of great merit, under the title of " Elemens de TArt de a communication whfeh I made to the Royal Society in 1773, mentioned in the last chanter of this work, I distinctly ascribed the production of ink and the black dye to this affinity between iron and the colouring matter of galls, and so far, at least, I had anticipated both Kier and Bergman. The first publication - ; jvr, on 'h : .s >Ukj of, wa«j I believe, in 1 7/6. lvi INTRODUCTION. la Teinture," in two volumes, which has been translated into English by Dr. Hamilton.* Before the publication of M. Berthollet's work, I had collected most of the materials for this un- dertaking ; and, though he has anticipated many things which I was prepared to mention, (some of which I shall notwithstanding mention in my own way,) this production afforded me great pleasure as well as profit ; because the author's superior chemical knowledge has enabled him to take just views of many intricate parts of his sub- ject, and to reason with great solidity, as well as sagacity, upon most of the operations of dyeing. He has, moreover, enabledme to abridge my own work, by referring, as I must do to his, for more ample information upon several topics, particularly those of fuel, the different acids, alum, the sul- phates of iron, copper, and zinc, verdigrise, acetite of lead, the different alkalies, soap, sulphur, arsenic, and water, of all which he has treated so ably and fully as to leave but very little for me to add respecting any of them. But though I have been preceded by authors of such distinguished ability as Mr. Henry and M. Berthollet, the new facts and observations * Since the above was written in 1/94, a new and improved edition of the " Elemens de l'Art de la Teinture" has been published by M. Berthollet, conjointly with his son (lately de- ceased) and all my quotations from the Elements, &c. are to be understood to have been made from this new edition, unless the contrary be stated. INTRODUCTION. Ivii which I here offer to my readers, will shew that I did not find the subject exhausted : And, indeed, it is so far inexhaustible, that it probably will afford ample employment for the greatest talents and industry during many generations. Injustice to that very eminent and respectable chemist, M. Chaptal, I ought to mention that his excellent work, intitled " Elemens de Chimie," (in three volumes,) contains many ingenious facts and observations relating to the causes of the production and changes of colours, as well as to several other subjects connected with dyeing : And to these he has since made considerable ad- ditions in his most valuable work intitled " Chymie appliquee aux Arts" in four volumes 8vo. which was published soon after lie had, with great difficulty, obtained permission 10 resign his office of minister of the interior of France, and return to his early and favourite pursuits. M. Vitalis, of Rouen, hasako recently published a small but useful work, intitled, Manuel du Teinturier sur fil & sur coton file. Some other works deserving of notice have also, within a few years, been published on this subject, particularly a French translation of that of Scheffer, with notes, by the celebrat- ed Bergman ; another by Pcerner, which has been translated into French from the German, and published with notes by Desmarets and Berthollot ; and a third by Dambourney ; iviii INTRODUCTION. but neither of these has done much towards- improving the theory of dyeing. That of Peer- ner contains an account of many experiments made by the author, with different dyeing drugs ; but, unfortunately, his reasonings upon them, and upon every part of the subject, are highly defective. Dambourney (a respectable merchant) was possessed of no chemical science, and he has done little more than give an account of the trials which he made with a considerable number of vegetable matters ; few of which are likely to be ever much, if in any degree, employed by dyers. Calico printing, though practised for many ages in some parts of Asia, seems not to have been seriously attempted in Europe, until the 18th. century ; and its progress, as well as introduction, were, for a considerable time, chiefly the result of British ingenuity and industry. Of their effects, some account will be given at p. 041 et seq. of this volume ; and I shall only add here, that, about the year 1 750, it was computed that fifty thousand pieces of linen and calico were annually printed in Great Britain, and chiefly in the neigh- bourhood of London ; though, at that time, there was no calico printing in France, and the French government, to favour their silk manufac- tures, had prohibited, under severe penalties, the wearing of chintzes, and printed linens and cottons. In 1759, however, these prohibitions were annulled. INTRODUCTION. lix Eminent writers have derived the arts of dye- ing and calico printing from a considerable degree of perfection, which they suppose chemistry to have somewhere attained in remote ages, though afterwards lost ; and they imagine that particular processes of the art were preserved after the principles on which it was founded had been for- gotten.* I am not able, however, to perceive any sufficient ground for these opinions. In fact, there is no good reason to believe, that chemistry ever had made any such progress among the ancients, or that they ever were so much engaged in the pursuit of knowledge by experiment, as would have been necessary for the acquisition of but a moderate portion of chemical science.! Even the operations of calico printing, as prac- tised by the people of India, and which, above all others, have been considered as the result of an improved state of chemistry, are, in many respects, highly inconvenient, and incumbered with uselejs parts, which a little chemical know- ledge would . have taught them to reject, as, in- * See Mr. Henry's paper in the third volume of the Me- moirs of the Manchester Society. Also Hist, and Memoires de l'Acad. R.des Sciences, &c. 1/50, and 1/66. f Piiny observes, that dyeing had never been considered as a liberal art ; and he alleges this as an excuse for not giving a rationale of it. Lib. xxii. c. 2. But this was a mere excuse, because no degree of science then in the world could have enabled him to do so. lx INTRODUCTION. deed, they were rejected by the people of Europe, very soon after calico printing began to be prac- tised here, though it began and was continued for some time with very little aid from chemical science. And, considering how far many of the operations of dyeing and calico printing have been carried towards perfection, unassisted by principles, we may say of this art, or, until very lately, might have said what Lord Bacon says of music, that " the practice has been well pursued, and in good variety, but the theory weakly ; especially as to assigning the causes of the prac- tice." Bacon's Works, by Mallet, vol. iii. p. 29. But though the observations of many indivi- duals, occupied with the means and operations of dyeing, through a long succession of ages in dif- ferent countries, joined to very important acci- dental discoveries occurring from time to time, have produced great improvements in this art, with very little help from theory, we are not to infer that a knowledge of its true principles, and of the causes which operate in producing its various effects, will not prove useful in the highest degree; for, (as Mr. Henry has well observed) " though long experience may establish a number of facts, yet, if the rationale of the manner by which they are produced be not understood, misapplications are liable to be made; similar practices are pursued where the cases differ essentially ; and improvements are attempted at INTRODUCTION. lxi hazard, and often on false principles." And in confirmation of these truths, perhaps I cannot better conclude this Introduction, than by adding the following quotation from the History and Memoirs of the Royal Academy of Sciences at Paris, for the year 1761 . viz, " La description des arts,faite avec line exacti- tude eclairee, depouillee de toutes les pratiques inuliles, que V ignorance tot/jours mysterieuse y accumule sans cesse, 8? reduite aux principes con- stans de la saine theorie, est pcufetre, le moyen le plus propre a hater leur perfection, et a j^endre plus abondantes ces sources de biens & de com- modites, que Tetre supreme a voulu. que les hommes dussent a leur travail, et a leur indus- trie." ERRATA. The reader is desired lo correct the follomng more considerable errors of the press, viz. VOL. I. Page 127, line 2 of the note, for " capha" read " bapha." 255, — 1, for " besehryving" read " besehryving." 256, — 10, for " historic" read " histoire." 400, — 11, for " 1806 read " 1306." 519, — 10, for " pits" read " parts." VOL. II. Pa< e 60, -148, for « Chap. II." read " Chap VI." at bottom, add the following line omitted, viz. " nary means for precipitating it, &c." 278, line 1, for " Majrt'h"read " Manjit'h." 284, — 18, for " Cocurdoux," read " Cceurdoux." 286, - 6, for " Rabee"read " Kabec." 13 of note, for" Morreau" read u Monnet." ■23, for " chebula terurinalia" read u terminalia chebula." 398, — 410, — CONTENTS OF VOL. I. Page. Introduction, concerning the origin and progress of dyeing and calico-printing xix PART I. Chap. I. — Of the permanent colours of natural bodies.. . 1 Chap. II. — Of the composition and structure of the fibres of wool, silk, cotton, and Jinen 83 Chap. III. — Of the different kinds and properties of co- louring matter employed in dyeing, calico-printing, Ike. Ill Chap. IV. — Of substantive animal colours, and principally of the Tyrian purple 1 20 Chap. V. — Of vegetable substantive colours, and princi- pally of indigo, and the plants affording it, or a similar colour 165 Chap. VI. — Of mineral substantive colours 313 PART II. Chat. I. — Of adjective colours generally, and their bases j with an illustration of their effects upon each other, as exemplified by Oriental and European calico-printing. . 34i Chap. II. — Of adjective colours from European insects, and principally from the kermes, or coccus illicis, Linn. 393 Chap. III. — Of the natural history of cochineal 410 Chap. IV. — Of the properties aud uses of cochineal ; with an account of new observations and experiments, calcu- lated to improve the scarlet dye 440 EXPERIMENTAL RESEARCHES CONCERNING THE PHILOSOPHY OF PERMANENT COLOURS, PART L CHAPTER I. Of the permanent Colours of Natural Bodies, ** Ceux qui exigent qu'on lenr donne la raison dun effet a general, ne connoissent, ni 1'etendue de la nature, ni " les limites de l'esprit humain." M. de Bcffon. The subject of this chapter was covered with darkness until the immortal Newton threw light upon it, by dissecting, if I may so express myself, the matter of light itself. By his Ex- periments we have been taught, that " the light of the sun consists of rays differently re- frangible;" and that, when separated by the prism, in consequence of their different degrees of refrangibility, they afford all the various shades of colour, running gradually into each other, according to their particular degrees of refrangibility ; the violet being most refracted ; the indigo next ; then the blue, green, yellow, orange, and red, which last is of all others, the least refracted ; that the same rays also differ in degrees of refiexibility, according td their de- grees of refrangibility. That the proper colour of homogeneal light, B PHILOSOPHY OF depending on its particular degrees of refran- gibility, cannot be changed by reflections or refractions ; and " if the sun's light consisted of but one sort of rays, there would be but one colour in the whole world," nor the possibility of producing any new colour by reflections and refractions ; and. therefore, " that the variety of colours depends upon the composition of light." That " colours, in an object, are nothing but a disposition to reflect this or that sort of rays, more copiously than the rest ; in the rays, they are nothing but their dispositions to propa- gate this or that motion into the sensorium ; and in the sensorium, they are sensations of those motions, under the forms of colours" That " colours may be produced by compo- sition, which shall be like to the colours of ho- mogeneal light, as to the appearance of colour, but not as to the immutability of colour, and constitution of light ; and those colours, by how much they are more compounded, by so much are they less full and intense ; and by too much composition they may be diluted and weakened, till they cease, and the mixture becomes grey. There may be also colours produced by com- position, which are not fully like any of the colours of homegeneal light." "For a mixture of homogeneal red and yellow, compounds an orange, like, in appearance of colour, to that orange, which, in the scries of unmixed prismatic PERMANENT COLOURS. 3 colours, lies between them ; but the light of one orange is homogeneal as to the refrangibility, and that of the other is heterogeneal ; and the colour of the one, if viewed through a prism, remains unchanged ; that of the other is changed, and resolved into its component colours, red and yellow. And after the same manner other neigh- bouring homogeneal colours may compound new colours, &c." And if to a colour so compound- ed, other colours be added in sufficient quan- tities, they will gradually overcome the first, and produce " whiteness, or some other co- lour." " So if to the colour of any homogeneal light, the sun's white light, composed of all sorts of rays, be added, that colour will not vanish or change its species, bat be diluted; and by adding more and more white, it will be diluted more and more, perpetually." " Lastly, if red and violet be mingled, there will be gene- rated, according to their various proportions, various purples, such as are not like, in appear- ance, to the colour of any homogeneal light ; and of these purples, mixed with yellow and blue, may be made other new colours." "That whiteness, and all grey colours between white and black, may be compounded of colours, and the whiteness of the sun's light, is compounded of all the primary colours mixed in due pro- portion." To illustrate this, he produced white- ness, iirst by a mixture or re-union of the seve- B 2 4 PHILOSOPHY OF ral prismatic colours, and then, as he asserts, by mixtures of differently- coloured substances, in due proportions.* Each particular colour being, therefore, a pro- perty of that particular sort of ray which pro- duces the perception thereof, Sir Isaac Newton, concludes, that the permanent colours of natu- ral bodies arise from hence, that some of them " reflect some sorts of rays, others other sorts, more copiously than the rest. ' Minium re- flects the least refrangible, or red making rays most copiously, and thence appears red. Violets reflect the most refrangible, most copiously, and thence have their colour, and so of other bo- dies ; and, " whilst bodies become coloured, by reflecting or transmitting this or that sort of rays more copiously than the rest, it is to be con- ceived that they stop and stifle in themselves, the rays which they do not reflect." Sir Isaac Newton's demonstrations and illus- trations of this doctrine may be seen at large in the first Book of his Optics, to which I refer, without intending to propose any ob- jection thereto. It may, indeed, be liable to * This last assertion appears incredible, unless the coloured substances were all transparent. A painter, I am confident, ■would never produce white from any or all of the several opaque colours, in whatever proportions they might be mixed j and the Dyer who should, in the usual ways, apply them to a piece of white cloth, would soon find it become black. PERMANENT COLOURS. several ; but as these, even if well founded, would not affect my ultimate conclusions, I shall thus far adhere to the Doctrine under consideration-. Sir Isaac Newton's second Book, however, contains matter to which I cannot assent. He begins it with " Observations concerning the reflections, refractions, and colours of thin transparent bodies ;" and mentions what had been observed by others, " that transparent substances, as glass, water, air, &c. when made very thin by being blown into bubbles, or other- wise formed into plates,* do exhibit various colours, according to their various thinness ; although at a greater thickness they appear very clear and colourless." And though he consi- ders these colours as "of a more difficult conside- ration" yet as " they may conduce to farther discoveries for completing the theory of light, especially as to the constitution of the parts of na- tural bodies , on which their colours or transparency depend" he delivers his own observations on this subject: Of these, the principal was made, by taking " two object glasses, the one a plano-con- vex, for a fourteen-foot telescope, and the other a large double convex, for one of about fifty foot; and upon this, laying the other with its plane side downwards, I pressed them slowly together, says he, to make the colours successively emerge in the middle of the circles, and then slowly - - ,*v 6 PHILOSOPHY OF lifted the upper glass from the lower, to make them successively vanish again in the same place. The colour which, by pressing the glass- es together, emerged last, in the middle of the other colours, would, upon its first appearance, look like a circle of a colour, almost uniform from the circumference to the centre; and by compressing the glasses still more, grow conti- nually broader, until a new colour emerged in its centre, and thereby it became a ring, encom- passing that new colour ; and by compressing the glasses still more, the diameter of this ring would increase, and the breadth of its orbit, or perimeter, decrease, until another new colour emerged in the centre of the last ; and so on, until a third, a fourth, a fifth, and other follow- ing new colours successively emerged there, and became rings encompassing the innermost colour; the last of which was the black spot: And, on the contrary, by lifting up the upper glass from the lower, the diameter of the rings would decrease, and the breadth of their orbit increase, until their colours reached successively to the centre ; and then they being of a con- siderable breadth, I could more easily discern and distinguish their species than before." And these he found to be in succession from the black central spot as follows, viz. first, blue, white, yellow, and red; then in the next circuit pr order, immediately encompassing these, were PERMANENT COLOURS. 7 violet, blue, green, yellow, and red ; in the third circuit or order were purple, blue, green, yellow, and red ; after this succeeded in the fourth cir- cuit, green and red ; then the fifth of greenish blue and red ; next the sixth, of greenish blue and pale red ; and lastly, the seventh, of green- nish blue and reddish white : but the colours in the last three circuits he describes as having been very indistinct, and ending in perfect white- ness. " By looking through the two object glasses;" continues he, " I found that the interjacent air exhibited rings of colours', as well by transmit- ting light, as by reflecting it. The central spot was now zvhite, and from it the orders of the colours were yellowish red ; black, violet, blue, white, yellow, red ; violet, blue, green, yellow, red, &c. But these colours were very faint and dilute, unless when the light was trajected very obliquely through the glasses. Comparing the coloured rings made by reflexion, with those made by the transmission of light, I found," • adds he, " that white was opposite to black, red to blue, yellow to violet, &c." And as rings of similar colours were observed in bubbles, " blown with water, first made tenacious by dissolving a little soap in it," Sir Isaac Newton endeavoured mathematically to ascertain the different comparative thicknesses of air, water, and glass, at which the several circuits or orders 8 PHILOSOPHY OF of colours appeared as before mentioned, winch he has noted in a table prepared for that pur- pose, and from which this remarkable fact ap- pears, that similar colours in the different orders occur, and are repeated over and over agabi at very great diversities of thickness ; a circum- stance which in my humble opinion, proves in- contestably, that though thickness might be one, it could not be, as he supposes, the only cause of these repeated variations of colour * It was, at that period, the fashion to ascribe even chymical effects to mechanical causes: alkalies were supposed to neutralize acids, as the blade of a sword is sheathed by its scabbard ; and the most learned physician of his age, soon after, thought it pro- per to write a Mechanical Account of Poisons. We are not, therefore, to wonder that Newton himself should have been misled on this sub- ject, since the whole amount of chymical know- ledge in his time, had he possessed it, would, like an ignis fat uus, have only served to light * Sir Isaac Newton seems to have foreseen this objection to his hypothesis, and to have endeavoured to obviate it, by sup- posing the existence of what he denominated different orders of colours ; in each of which it was conceived that the red, orange, yellow, &c. required for their production very different thick- nesses from those which produced the same colours in the other orders : this, however, was but a supposition, improba- ble in itself, and repugnant to a multitude of facts, which will be mentioned in the course of this work. PERMANENT COLOURS. 9 him astrav ; as in truth it seems, in some degree, to have done ; for, after stating as a proposition, that ii the transparent parts of bodies, accord- ing to their several sizes, reflect rays of one colour, and transmit those of another, on the same grounds that thin plates, or bubbles, do reflect those rays," he goes on to mention, " that, by mixing divers liquors, very odd and remarkable productions, and changes of colours, may be effected ; of which no cause can be more obvious and rational, than that the saline cor- puscles of one liquor, do variously act upon, and unite with, the tinging corpuscles of another, jo as to make them swell or shrink (whereby not only their bulk, but their density also, may be changed), or to divide them into smaller cor- puscles (whereby a coloured liquor may become transparent), or to make many of them associate into one cluster, whereby two transparent liquors may compose a coloured one :" and laying it down as a proposition, that " the bigness of the component parts of natural bodies, may be con- jectured by their colours," he endeavours, among other things, to explain why the syrup of violets, " by acid liquors, turns red, and, by urinous and alkali zate, turns green ;" and for this purpose, he supposes, that " it is the nature of acids to dissolve or attenuate, and of alcalies to precipitate or incrassate ;" a supposition, 10 PHILOSOPHY OF which, as acids and alkalies are chymical agents* is not true of either of them, in the sense in which Sir Isaac Newton appears to have understood it ; though, in another sense, it is partly true and partly false of both ; since both are capa- ble of dissolving a great variety of substances, and when a substance is dissolved by either it will most commonly be decomposed and precipitated by the other : but certainly the effect of coagulating, or incrassating, which he ascribes to alkalies, is much more frequently produced by acids ; though nothing like it is produced in any of the changes of colour, which they occasion to the syrup of vio- lets. It must be also observed, that Sir Isaac Newton has himself admitted, that what he calls " fat, sulphureous, unctuous bodies," pos- sess refractive powers " two or three times greater, in respect of their densities, than the refractive powers of other substances, in respect of their's ;" an admission, which seems incom- patible with the conclusion which he almost * When acids " dissolve or attenuate," it is by combining and forming a new compound with the matter so dissolved or attenuated ; and when alkalies, " precipitate or incras- sate," they always produce decompositions, and new com- pounds, which are totally foreign to those mechanical effects bj which, Sir Isaac Newton intended to explain the changes of colour in question. PERMANENT COLOURS. 11 immediately after draws, " that nothing more is requisite for producing all the colours of na- tural bodies, than the several sizes and densi- ties of their parts."* In thus extending and applying his conclu- sions, respecting the transient colours of pellucid plates and bubbles, to the permanent colours of all natural bodies, Sir Isaac Newton appears to * Since my objections to this part of Sir Isaac Newton's doc- trine wero published, Dr. Young, in the first volume of his lectures on Natural Philosophy, p. 46g, has delivered the fol- lowing observations respecting the Newtonian theory of tho colours of natural bodies, viz. " Sir Isaac Newton supposes the colours of natural bodies in general, to be similar to these colours of their plates, and to be governed by the magnitude of their particles. If this opi- nion were universally true, we might always separate the colours of natural bodies by refraction into a number of different por- tions, with dark spaces intervening ; for every part of a thin plate, which exhibits the appearance of colour, affords such a divided spectrum, when viewed through a prism. There are accordingly many natural colours in which such a separation may be observed ; one of the most remarkable of them is that of blue glass, probably coloured with cobalt, which becomes divided into seven distinct portions. It seems, however, im- possible to suppose the production of natural colours peifectly identical with that of the colours of thin plates, on account of the known minuteness of the particles of colouring bodies, un- less the refractive density of their particles be at least 20 or 30 times as great as that of glass or water ; which is indeed not at all improbable with respect to the ultimate atoms of bodies, but difficult to believe with respect to any of their arrangement! constituting the diversities of material substances." ^H 12 PHILOSOPHY OF have been influenced solely hy analogy ; hehav'mg made no experiment, or observation which would justify this extension. But in the year 1765, Mr. Edward Hussey Delaval, F. R. S. endea- voured to supply this omission, by commu- nicating some experiments, and observations, on the agreement between the specific gravi- ties of the several metals, and their colours, when united to glass, as well as of their other preparations," in a letter to the Earl of Morton, then president of the Royal Society : a com- munication for which the Society bestowed on him the annual gold medal provided by Sir Godfrey Copley. And though Mr. Delaval, in this communication, " treats of the difference of density, and the colours produced by that cause," he, notwithstanding, considers these as connected with " the colours arising from a difference of the size of the colouring particles ;" since, " by separating the particles of a coloured substance, they are removed to a greater dis- tance from each other, so as to occupy more space," and, therefore, the substance so affected, " must undergo a diminution of its specijic gra- vity, at the same time that the size of its parti- cles is lessened." And as Sir Isaac Newton had inferred, that the refractive and reflective powers of bodies, were nearly proportional to their densities, and that the least refrangible rays, require the greatest power to reflect them, PERMANENT COLOURS. 13 Mr. Delaval conceived, " that denser substances ought, by their greater reflective power, in like circumstances, to reflect the less refrangible rays ; and that substances of less density, should reflect rays proportionably more refrangible, and thereby appear of several colours, in the order of their density." And, in support of this opi- nion, he undertook to " give instances of natu- ral bodies, which differ from each other in den- sity, though circumstanced alike in other re- spects;" and also differ " in colour, in the same order as they do in density ; the densest being red, the next in density orange, yellow, &c. " In such an inquiry," says he, " metallic bodies seem to demand our first and principal attention, as their specific gravities have beeu ascertained, by well-known and repeated experi- ments." Mr. Delaval, however, must doubt- less have perceived, that metals, in their pure simple forms, could not suit his purpose of sup- porting and extending the doctrine of Sir Isaac Newton, in this respect ; since platina, which is much the heaviest of all metals, and of all known substances, instead of being the most red, as upon this hypothesis it ought to have been, is white, like tin, the lightest of metals ; and gold, the heaviest of metals after platina, is much father removed from the red colour than copper, which is so much lighter. And this is more remarkably the case of quicksilver, lead, &c. To 14 PHILOSOPHY OF obviate so formidable a difficulty, he thought it expedient to premise, that, " as the inflammable matter in the entire metals, acts strongly on the rays of light, it is necessary to calcine, or divide them into extremely minute particles, in order to examine separately the action of the calx, or fixed matter, on the lays of light." But here, at the very threshold, Mr. Delaval is forced to suppose the presence of what he calls inflam- mable matter acting strongly on the rays of light , and thus producing or changing colours, by pro- perties very different from those of density, and size or thickness of particles. I might here deny, as, in truth, I am very far from believing, the existence of any such matter in metals, which, according to the new and prevailing chymical doctrine, are simple substances, uncombined with any such matter as is here supposed. Ad- mitting, however, for the sake of argument, that phlogiston, or inflammable matter, does exist in metals ; it must be recollected, that their calci- nation is not a mere abstraction thereof; since there is no fact in chymistry better ascertained > than that every metal in its calcination unites with a considerable portion of vital air, or its basis, the oxygene* of the modern chytnists, and which * By oxygene is meant that substance which, combined with and rendered elastic by heat, or by heat and light, con- stitutes vital air j or what Dr. Priestley terms dephlogisticated PERMANENT COLOURS. 15 (only by variations of proportion) is capable of producing, with particular metals, (and with other substances), all the possible variations of colour. Of this, however, Mr. Delaval takes no account: indeed, when treating of the colours of Mercury, he expressly says, " I have not entered into the consideration of the air, which unites with mercurial colours during their expo- sure to fire ; because it docs not relate to the greater or less division of their particles, which is the immediate subject of my inquiry." So that, air (first discovered by him in August 17/4), the only fluid suited for respiration ; the pabulum vitcc, without which the more perfect animals cannot live, even for a few minutes. But as the stimulant or exhilarating effects of this (vital) air would excite, and wear out, the powers of life too much and too rapidly, if it were inspired without mixture, the wise Author of Nature has presented it to us diluted with nearly four times as much of a different air not respirable by itself, and which it now denominated azote, or nitrogene. These two airs, with a very small portion ol carbonic acid gas, or fixed air, and some accidental or extraneous matters, compose our common atmospheric air. The oxygene, combined with nitrogene, con- stitutes, according to their different proportions, eilher the nitrous or nitric acid ; the same oxygene united to sulphur by combustion, produces either sulphureous or sulphuric (vitriolic) acid 5 and, with other baies, it seems to produce most of the other acids. With pure charcoal (carbone) it produces car- bonic acid (or fixed air), and with inflammable air (hydrogene) it produces water. This explanation may be useful to readers not acquainted with the modern chymistry. 16 PHILOSOPHY OF by his own statement, he has overlooked (be- cause it did not suit his hypothesis) the only iking worthy of notice on this subject ; since the oxyds or calces of Mercury, and, indeed, of all other metals, indisputably receive their various colours only by additions, greater or smaller, of that air which he professes to have disregarded; and which, as he declares, has no relation to the greater or lesser division of their particles; and we must therefore conclude, that the various colours assumed by these calces, under the cir- cumstances in question, do not result from any such division. But though Mr. Delaval inculcates the ne- cessity of calcining metals, " in order to exa- mine separately the action of their calces or fixed matter, on the rays of light," he does not adduce the colours which they assume when so calcined, as any evidence of the truth of his hypothesis ; and, indeed, he might have perceived them to be absolutely incompatible with it, siuce the same oxyd, by different degrees of calcination, exhibits very great diversities of colour. But in order to obtain from several of the metals such colours as suited his purpose, he continued to melt them with what he was pleased to think " a quantity of the purest glass," and as they, when more or less calcined, and melted or united with a greater or less portion of glass, are capable each of giving several, and some of PERMANENT COLOURS, 17 giving all the colours, it could not be difficult for him to find out, and assign to each metal, as its proper colour, that which it ought to have, upon his supposition that the colours of metals depended on their respective densities. Thus, for example, iron highly calcined, or combined wi !i a large portion of the basis of vital air, (oxygene,) gives a red colour to melted glass; and if the glass be continued in fusion, the (oxygene) will by degrees be separated, and in proportion to its separation, the colour of the glass will change to orange, yellow, green, blue, and white. And as blue is the colour which suits Mr. De- laval's purpose, he selects and assigns it as the proper colour of iron, and the degree of heat producing it, as the proper one for manifesting those which suits him to consider as the true colours of metals ; though in fact he took no means to ascertain what this degree of heat really was ; and the effect, or blue colour, would require very different degrees, according to the greater or lesser degree of calcination which the iron had previously undergone, or, in other words, according to the quantity of oxygene previously combined with it. Where every thing is in this way assumed or supposed at pleasure, not only without evidence ot probability, but often against both, it must have been easy for Mr. Delaval to give some plausibility to this fallacious hypothesis, though it 18 PHILOSOPHY OF is absolutely incompatible with a multitude of facts. Mr. Delaval has quoted, from Glauber's Prosperity of Germany (translated by Packe, 1689), some curious observations respecting the various colours produced by manganese ; and he adds, as from his own knowledge, that " amongst the mineral substances none affords a greater variety of bright colours, especially when it is fused with nitre, or a fixed alkali ;" of these he instances a yel- low, produced by dissolving manganese in a weak spirit, together with a green, blue, purple, and red, produced by water poured on it; iu the first instance cold, and in the others warm, then warmer, hot, and boiling; all which co- lours he ascribes to different degrees of solution, or attenuation, of the particles of manganese. But in truth this and other metallic calces or oxides, had he properly attended to their various changes of colour, might have shewn him both the fallacy of his own hypothesis, and the road to a better. Manganese is the oxide or calx of a metal which has so strong an attraction for the basis of vital air, that one of the most excellent of chymists, Berthollet, says, we m may safely consider the whole of what exists in nature to be as in a state of oxidation, or combination with oxygene : when saturated therewith, I mean with the basis of vital air, it is black ; and if it PERMANENT COLOURS. 19 be diluted or diffused in melted glass, it becomes purple, or red ; and as the vital air diminishes by burning with the coaly impurities, (which it is employed to destroy,) in glass, it gradually loses its power of producing colours, and leaves the glass colourless; though its colours may be restored by nitre, or any thing affording pure air. The different solutions of man- ganese, mentioned by Glauber, and others, undergo their various changes of colour, in con- sequence of a gradual separation or diminution of their oxygene ; and that this is what manga- nese possesses, and what it loses, in these opera- tions, is well known to all who are acquainted with the later chymical discoveries. I have already noticed the various colours assumed by the oxides or calces of iron, when combined with different portions of the fame air, or its basis, the oxygene, which are indeed so many and various, that I remember having been told by the late Mr. Wedgwood, that all the diver- sified colours applied to his pottery, were pro- duced by the oxides of this single metal; which must have been all of very nearly the same specific gravity, and they were besides, in these cases, combined or melted with glass, the sub- stanee which Mr. Delaval thought proper to choose, as being of all others the best, for exhi- biting what he was pleased to think the true colours of metals. In like manner the oxides c 8 20 PHILOSOPHY OF or calces of mercury, lead, copper, &c. assume each a variety of colours, by combinations with different portions of oxygene, without any thing like a correspondent variation of density, or of specific gravity in any of them. Of this Mr. Delaval appears to have been sensible, at least in the instance of lead, and he endeavours to obviate the evidence which it affords against his theory, by ascribing the various colours of that metal to its "imperfection," which he is pleased to suppose, without any, and against every, kind of proof and probability : and then he proceeds to say, " it is probable that, during the calcina- tion, lead receives a small portion of phlogiston, as well as of air; for the affinity between the earth of this metal and inflammable matter is very great, as appears from the readiness with which its solutions and calces unite with phlo- gistic vapours. " The effect of such an union," he adds, " must probably be a change of colour from orange to red ; for Sir Isaac Newton has shewn, that bodies reflect more strongly in proportion as they possess more phlogiston, and that the less refrangible colours require greater power to reflect them." Here we have another gratuitous and strange supposition of an acces- sion or combination of phlogiston with lead in calcination : I say strange, because those of the adherents of phlogiston who yet continue to believe its existence in metals, have constantly PERMANENT COLOURS. 21 supposed that, in calcination, while they re- C( ,! air, they lost, instead of gaining, injlam- ma .attcr. But were this extravagant sup- p m to beadmitted as a cause of the changes >Iour in metals, how can it be reconciled to any hypothesis which makes their colours depend on their respective densities? Indeed, if the effects which Sir Isaac Newton supposes phlogiston to produce on colours were real, and if phlogiston existed in them, as lie and Mr. Delaval imagined, it would be difficult to con- ceive why all metals are not red, or more in- clined to redness, than their calces or oxides. But enough, perhaps too much, has been said, to refute Mr. Delaval's hypothesis, so far as it relates to the colours of metals. Unfortunately, however, for my readers, as well as for myself, he has thought proper, in a larger work,* pub- lished some time since, to extend the same hy- pothesis to the colours of animal and vegetable substances ; and has endeavoured to confirm and illustrate Sir Isaac Newton's ideas on this sub- ject, by a variety of experiments, which are represented as instances of changes of colour produced in these substances, by an increase or diminution in the sizes of their particles: I am, therefore, compelled reluctantly to extend my * Experimental Enquiry into the Cause of the permanent Colours of opake Bodies. 4to. 22 PHILOSOPHY OF own observations a little farther on this subject; and I must begin by complaining of a conti- nuance of gratuitous and fallacious suppositions, similar to those which I have before had occa- sion to notice ; for when, in operating upon, or with different matters, he professes cither to in- crease or diminish the sizes of their particles, and to do nothing more, (to shew that the changes of colour produced in them, accord with the thicknesses stated in the table of Sir Isaac New- ton,) instead of choosing and employing mecha- nical means, which alone are suited td produce these, and only these effects, he has recourse to mere chymical agents, whose action in the ways which he supposes, must have been always doubtful at least, though their powers of pro- ducing other, and very different effects from any supposed by him, is most certain. Mr. Delaval, however, adopting Sir Isaac Newton's suppo- sition, that acids always attenuate, and alkalies always incrassate, prepared what he considered as a dissolving or attenuating liquor; which " consisted of water, with about an eightieth part of aqua fort is : and when he wanted to lessen the dissolving force of this liquor, instead of weakening it by the addition of water (which would certainly have been the most obvious and unexceptionable expedient), he chose to do it, as he says, by adding "a small quantity of a solu- tion of potash, or some other alkaline liquor ? PERMANENT COLOURS. 23 and thereby produced a new composition, the effects of which must, in many cases, prove dif- ferent from those of a mere diminution of the supposed dissolving power of the former liquor. And on the other hand, when he wanted to increase the force of his acid liquor, instead of doing it by a farther addition of aqua fortis (obviously the most proper expedient), he recurs to an addition of oil of vitriol; an acid possess- ing very different properties, and producing very different effects, on a great variety of sub- stances, and particularly on colouring matters ; of which I could allege hundreds of instances, but shall content myself with only mentioning, that the strongest and most concentrated oil of vitriol (used to dissolve indigo for dying the Saxon blue,&c.) does not destroy, or even weaken, its blue colour, though a diluted nitric acid, or aqua fortis, will wholly destroy it, and convert the indigo to a dirty brown mass, of no use whatever. Having thus assumed, that acids attenuate, and do nothing but attenuate, the particles of colouring matter; that alkalies incrassate, and doing nothing but incrassate, the same particles ; that by adding an alkali to his mixture of aqua fortis and water, he weakens, and only weakens, its attenuating force on one hand ; and that on the other he increases, and only increases it, by an addition of vitriolic acid ; he next provides 24 PHILOSOPHY OF himself with so much of Sir Isaac Newton*? table before mentioned as suits his purpose, by transcribing the different colours of the three first orders, and the different thicknesses of air, water, and glass, supposed to produce each of these colours, one after the other; and thus equipped, he proceeds to make experiments upon red infusions, of certain vegetables, and generally finds, that with his acid liquor, the colour continues red ; that, with the addition of oil of vitriol, to attenuate farther, (as he sup- poses) it becomes yellow; and that if, instead of oil of vitriol, he adds an akali, to incrassate, it becomes a purple. Now it so happens, that though all the other colours are repeated in more than one order, purple is marked but once in Sir Isaac Newton's table, and then it is placed as the first colour of what he terms the third order; and if the red and yellow, from which the purple in question had proceeded, were supposed to be of the same order (as might be expected), then the production of this purple ought, upon Mr. Delaval's theory, to result not from incrassation, but from attenuation ; since the particles of it are stated to be nearly one- third less in size, than the particles of the red, and nearly one-fourth smaller than those of the yellow of the same order: but such is the happy arrangement of this table, and of the several orders of colours, that, by supposing the red in PERMANENT COLOURS. 25 this instance to be the red of the second order, he finds a purple below it in the third, with only one intervening colour, and a yellow at the same distance above ; and by these leaps, he reconciles the appearances to the theory. In- deed, as the second, or middle order in the table, contains all the different colours, and as, except- ing one, they are all repeated in the first order, which is above; and also in the third, which is below; hardly any change of colour can hap- pen, which may not be made to accord with Mr. Delaval's hypothesis, he being always al- lowed to suppose each original or primitive colour to belong to that order which may be most convenient for his purpose ; though, in truth, the very admission of different orders or repetitions of the same colours, produced repeatedly by and at different thicknesses, or sizes, either of particles or plates of matter, is of itself a proof (as I have before observed) that such colours do not depend on any particular thickness of plates or size of particles.* * When Mr. Delaval, on every occasion, allots each par- ticular colour to some one order, exclusively of the rest, it would seem reasonable to expect, that he should justify this allotment by something besides his own convenience, and par- ticularly that he should prove that the red, for instance, which l\e places in the second order, exceeds that of the first order, in the density and size of its particles, exactly in the same pro- portion as 18^ exceeds 9 ; and that the red which he places 26 PHILOSOPHY OF I am far from thinking that Mr. Delaval has always chosen the matters, most proper for fair experiments, or that the experiments them- selves, even on his own principles, were well calculated to ascertain the truth. But such as they are, I can readily point out several, which, on his own improbable, or rather impossible supposition, of mechanical attenuation or incras- sation, and nothing else, by chymical agents, cannot be reconciled to his theory, even by the assistance of Sir Isaac Newton's covenient table. The green leaves of the anil (indigofera) and glastrum, he says " being long steeped in water, their partq are dissolved into a blue substance, whic 1 ^ is' indigo and woad." Now the truth is, in the third order, exceeds that of the second exactly in the proportion of 2Q to I83- : and that the other colours of the several orders, differ from each other likewise, according to the proportions stated to be necessary for their production, in the table which he has adopted from Sir Isaac Newton. Before this division of colours into orders, and the hypothesis con- nected with it, can be admitted to have any other than an ima- ginary foundation, it ought to be proved, that all the known reds, differ from each other in respect to the densities [and sizes of their particles, exactly according to the before-mentioned pro~ portions ; and so of the oranges, yellows, &c. since, in every case, the slightest deviation from the thickness or size of par- ticles, stated as essential to the production of a particular colour, ought to occasion the appearance of that colour, which is next in the series above or below. But nothing like this is any where attempted, nor is there any thing accessible to human observation, which could in any degree justify the attempt. PERMANENT COLOURS. 27 that the blue arising from these vegetables is not the result of any dissolution, but of an absorption of pure air, during the fermentation which they undergo ; and this colour does not manifest itself, until there is a beginning aggregation and concretion of its matter, into larger particles, which becoming denser, as well as larger, sink down to the bottom, leaving the water nearly colourless. So that here the change from green to blue, is manifestly accompanied with an in- crease, both in the size and density of the co- loured particles, which is absolutely incompa- tible with Mr. Delavai's hypothesis ; since, ac- cording to the table in question, every change of colour from green to blue is the effect of a diminution, not an increase, in the size and den- sity of its particles. When the indigo itself (formed into dry masses) is to be dissolved for dying, by the combined action of caustic alkalies, and of particular chymical attractions, or vegetable ferments, the solution, though manifestly attended with a division or diminu- tion of the coloured particles (as well as a loss of the air absorbed during the first process) be- comes green, contrary to the table and hypothe- sis in question ; and in this state, it is applied by the dyers to wool, and other substances, to be dyed ; and these, when first taken out and exposed to the air, appear green ; but by ab- sorbing, and uniting with a portion of oxygene. 28 PHILOSOPHY OF they immediately become blue, and in doing so, the divided particles again concrete into larger ones, as must be evident, among other proofs, from this, that the surface of the indigo liquor, on which the air has an immediate action, is from that cause always blue ; and if we skim off this blue matter, (which is nothing but indigo revived) it will be found impossible to make it enter the pores of any substance, so as to dye a permanent colour therewith ; be- cause the particles having regained their pro- per portion of pure air, or its basis, are no longer sufficiently divided and dissolved for that pur- pose ; so that in all these cases, the matter of indigo becomes more dense, and its particles larger, in passing from green, to the more re- frangible colour, blue ; and the contrary, in passing from blue to the less refrangible colour, green. And this is also the case, when the infusions of rhubarb, turmeric, &c. are made " to descend (as he expresses it) from yellow to orange and red," " by the addition of an al- kali," which, whatever he may imagine to the contrary, dissolves these colouring matters more powerfully than any acid. Similar objections occur, in opposition to the instances which Mr. Delaval alleges, respecting " the changes of Colour which animal substances undergo." Among these, e. g. he observes, that cow's milk, boiled up with an alkali, changes from white to PERMANENT COLOURS. 2!> yellow, orange, and red ; and, as usual, he gra- tuitously supposes, that, in producing these changes, it acts by incrassating, or coagulating the milk ; though if, contrary to all probability, alkalies were able to do this, we have no reason to conclude that such coagulation would ren- der the milk either yellow, orange, or red, be- cause no such colours appear when it really is coagulated by acids, &c. as in the making of curds and cheese. Out surely it cannot be necessary for me, seriously to combat such chi- meras any longer. The common sense and ex- perience of mankind, if fairly consulted, will condemn and revolt at the idea, of making the colours of bodies depend on their weight, or the sizes of their particles ; for it. certainly never has been observed, that the heaviest substances were red, or the lightest violet-coloured, or that bodies equally heavy were all of the same colour. Different Darcels of indigo, for instance, vary extremely as to specific gravity, without any variation of colour ; a fact which is not only at variance with Mr. Delavafs hypothesis, but which renders it easy to find samples of indigo, of exactly the same specific gravity as the colour- ing matter of cochineal (exhibited in what is called carmine,) which of all colours is the far- thest removed from that of indigo : and if Mr. Delaval should allege, that, though agreeing in weight, thev differ as to the sizes of their BBH ■i SO PHILOSOPHY Otf respective particles, let him correct this diffe- rence by the only means suited to do it, without doing more ; I mean by simple mechanical division, or grinding. Let this be employed upon either of the substances in question, whose particles he may suppose too large, as long as he shall think proper, and let us then see whether he can thereby render the colour of indigo red, or that of cochineal blue or violet. Should what I have said on this subject prove insufficient to convince any one of my readers, I only beg that he will follow me, with a mind open to -conviction, through the various in- stances, which, for other purposes, I shall have occasion to state hereafter, of colours produced, or changed by means, and in ways that are wholly irreconcileable to the theory in question, and I persuade myself that his doubts and difficulties will be effectually removed, so far as they may relate to the truth or fallacy of Mr. Delavafs hypothesis, of which I mean hereafter to be silent, because I dislike even the appearance of contention ; nor would I have so long detained my readers on this subject ; but from a convic- tion of the truth of what I have written, and of the expediency of refuting an hypothesis, incompatible with a considerable part of what I am about to offer to the public; an hypothesis which the name and authority of Sir Isaac New- ton had pre eminently sanctioned ; and which PERMANENT COLOURS. Si the learning and talents of Mr. Delaval had ren- dered so plausible, that it is, I believe, gene- rally considered as true, in this and other coun- tries.* Having shewn, that the permanent colours of different objects, do notarise from their den- sities, or the sizes of their particles, it becomes me to state such facts and observations, as seem best suited to throw light upon this obscure and interesting subject. Sir Isaac Newton having; found that inflam- mable substances, possessed greater refractive powers than others, in proportion to Uieir den- sities, says, in his second Book of Optics, that " it seems rational to attribute the refractive power of all bodies, chiefly, if not wholly, to the sulphureous parts with which they abound ; for, adds he, it is probable that all bodies abound more or less with sulphurs ;" a term by which he intended to distinguish inflammable matters ge- nerally. And this great man having also con- cluded, that the permanent colours of natural bodies, were analogous to the colours produced by the refractions of thin, colourless, transpa- rent plates, &c. chy mists were generally induced to make all colour depend on the principle of inflammability or phlogiston, which was sup- posed to exist in all metals, and many other sub- * Such was the fact in 1/94, when thif was first published. 32 PHILOSOPHY OF stances ; and where the total want of inflamma- bility was manifest, they confounded this, with the matter of heat and of light; to which they. ascribed the power of ph log is tic a ting other sub- stances, and of thereby producing or changing their colours : a species of confusion suited only to cover and perpetuate ignorance ; since every single colour is found to belong both to com- bustible and incombustible substances, and to neither exclusively. The combustible diamond, which Sir Isaac Newton conjectured to be " an unctuous substance coagulated," is found to be of almost all the different colours, whilst other gems, though of similar colours, are all incombustible. Combustible indigo, and in- combustible smalt, are both blue ; combustible vcrmillion and incombustible minium are both red; combustible gamboge, is yellow ; and so are certain incombustible oxides of lead, iron, and mercury. But since the existence of phlo- giston in metals, &c. has been denied by the pneumatic chymists, they have in most cases, attributed the origin and changes of colours, to the application or combination of different airs or gazes, and particularly oxygene in different proportions; and it has been supposed that these gazes, possessed considerable refractive powers, and were thereby enabled to produce effects on colours, like those which the followers of Stahl, had imputed to phlogiston : and M. Berthollet, in his recent work on the Elements PERMANENT COLOURS. 33 of Dying, intimates, that " many important observations still remain for those who would follow the steps of that great man (Sir Isaac: Newton), and compare the refracting powers of the different gazes, and other substances, the constituent principles of which are now known.'* * Ten years after my first edition of this volume was pub- lished, M. Berthollet (assisted by his son, lately deceased, aud too soon for the interests of science) favoured the pub- lic with an improved edition of the Elements de Teinture, in which (at page 33, of the first volume) he intimates, that it was his indention, by the words just quoted, to express some doubt of the correctness of this part of Sir Isaac New- ton's doctrine j and he adds, " depuis lors Bancroft lui a oppose un grand nombre de faits. Nous nous servirons de ses difierentes observations, dans la discussion que nous n'allons entreprendre,que dans la vue d'appeler sur cet objet interessanr, l'attention de ceux qui peuvent suivre les traces de Newton'* He then proceeds through nearly twenty pages to repeat the facts and arguments which I had employed on this subject, and to adduce other facts and arguments in their support, from all which he concludes, nearly as I had done, " qu'il ne faut point confondre les couleurs fugitives qui sont produites par la reflexion des lames, and qui suivent les loix determinees par Newton, avec les couleurs qui se conservent malgre les chan- gemens de densite and d'epaisseur. Celles-ci nous paraissent tenir a des proprietes, ou l'afllnite particuliere pour les diflferents rayons de la lumiere, a une influence qui resiste a celle des dimensions et de la densite; si nous examinons les faits, nous apercevons que loxigcne condense exerce un grand pouvoir dans cette espece d'affinite : une proportion un peu plu9 on un peu moins grande, qui afFecte d'une maniere inseu- 34 PHILOSOPHY OF Though it be true that the prism, and other transparent colourless substances, in dif- ferent forms, shew us the different colours of the several rays of light, by separating them from each other, in consequence of their greater or lesser refrangibility, or disposition to be " turned out of their way, in passingout of one transparent body or medium into another," (which may de- pend upon differences in their sizes, densities, or velocities,) yet the permanent colours of different bodies, or substances, are not, as I believe, produced by mere refraction, and Sir Isaac New- ton must have been misled by analogy when he extended his discoveries and conclusions respecting the trausient colours resulting from the refractions of light, by pellucid colourless substances, to the permanent colours of va- rious kinds of matter ; since the latter evi- dently depend on other properties, which determine, or occasion the reflection or trans- mission of some particular sort or sorts of rays, and an absorption or disappearance of the rest ; and these I conceive to be certain affinities, or elective attractions, existing in or between the differently coloured matters and the particular sorts or rays of light so absorbed or made latent ; and of which many instances and proofs will, I think, be found in the subsequent parts of this work. sible la pesanteur specifique des oxides metalliques,, y produit de grands cbangements de couleurs/' &c. PERMANENT COLOURS. 35 Next after the diamond and amber, we find that spirit of turpentine, linseed oil, olive oil, camphor and alcohol, or rectified spirit of wine, possess greater refracting powers, in pro- portion to their respective densities, than any of the other substances contained in Sir Isaac Newton's table, and yet they are all permanently destitute of colour ; a fact which does not seem to indicate any connexion between the refrac- tive power of a substance and its natural perma- manent colour. Nothing seems to act so power- fully and extensively in producing and changing those affinities, or elective attractions, from which the permanent colours of different sub- stances arise, as pure vital air, or its basis, the oxygene; which, indeed, seems to owe its elastic, or aerial form, to a portion of light as well as heat. Scheele demonstrated that gold, silver, &c. were revived from their oxides by the con- tact of light; and M. Berthollet has proved, that, in producing this effect, the light occa- sions a separation of oxygene, in the form of pure vital air. Light also separates oxygene from various other substances, to which it would otherwise remain united, under great degrees of heat. We are at this time well acquainted with the constituent parts of the acid of nitre : it unde- niably consists of nitrogene or azote, rendered acid by its combination with a certain portion of d 2 36 PHILOSOPHY OF oxygene, or the basis of vital air. When these ar? combined in a certain proportion, the acid or compound is colourless, as we see it in aqua fords, or nitric acid : but if this colourless acid, in a transparent glass vessel, partly filled, be exposed to the rays of the sun, or the light of a fire, an alteration will take place in the proportion of its ingredients; since the light will combine with a part of the oxygene, and cause it to become elas- tic and fly off, and the nitrogene will conse- quently predominate in the remainder ; which, becoming nitrous acid, merely in consequence of this predominance, Avill assume first a yellow, then an orange, and afterwards a high vivid aurora, and even a red colour, intensely affecting the sight. But if the glass vessel containing the colourless nitric acid, were completely filled with it. and closely stopped, no such change of colour would take place by any degree of exposure to the sun's rays or other light; because, in this case, there would be no sufficient space or room to allow of a separation and escape of the oxy- gene. When nitrous acid has been made tor assume the colours before mentioned, if the glass vessel containing it be hermetically sealed and kept for some time in the dark, the oxy- gene, by losing its light, will lose its elasticity ; and being again re-absorbed by the nitrous acid, the latter will become colourless, as before. Mr. Keir mentions an orange-coloured nitrous PERMANENT COLOURS. 37 • acid, which, by long keeping, became green, and afterwards of a deep blue; and Bergman says, that if, to a concentrated red nitrous acid, one-fourth part of the quantity or measure of water be added, the colour will be changed to a fine green ; and to a blue, by the addition of an equal measure of water; and that double its quantity of water will destroy the colour. Here then we have an example of all the various colours produced by the two species of air which almost exclusively compose our atmos- phere, when deprived of their elasticity, and mixed in particular proportions with more or less dilution by water. In the same manner, colourless nitric acid, when applied to wool, silk, fur, or the skins of animals, their nails, horns, &c. renders them all not only yellow, but c range, and even aurora- coloured. M. Berthollet thinks, these changes arc produced by a kind of combustion ; but I am persuaded they are the result of a combina- tion of the oxygene with the nitrogene, which lie has proved to be a constituent part of all animal substances ; these changes being exactly similar both in their nature and origin, to the changes of colour produced as before mentioned in the nitrous acid. Weic these colours the e.Tcct of combustion, why arc they not likewise produced in the same manner upon linens, and cottons, which are without nitrogene, but ecu- " 38 PHILOSOPHY OF tain a great portion of the basis of charcoal, and ought therefore to be more liable to be acted upon in the way of combustion, than animal substances ? Long before the properties of the several kinds of air were known, many changes of co- lour had been noticed as produced by the appli- cation or action of light ; and indeed its effects are so remarkable, in many cases, that no one can doubt of its powerful agency in these and other respects.* The principal thing to be as- certained on this point is, whether the colours which accompany, or require the application of light, result in each particular instance directly from a combination of it with the coloured sub- stance, or indirectly from its particular action in occasioning either a separation of oxygene, or a combination thereof with the coloured matter ? M. Sennebier attributes the effects of light upon colouring matters, to a direct com- bination of the former, with the latter ;f but of * Light not only contributes most efficaciously to the pro- duction of some colours and the destruction of others, but it greatly weakens the texture, and fibres of silk, linen, cotton, &c. when they are long exposed to the direct action of the solar rays; as may be seen in window curtains, blinds, &c. which, from that cause only, will, in a few years, tear as rea- dily as brown paper. f See " Mem. Physico-Chymiques sur 1'Influsnce de la Luoiiere Solaire," &c. torn. ii. and iii. PERMANENT COLOURS. S3 this, though it may be true, he lias not alleged any sufficient evidence, so far as I*am capable of judging ; and there are many facts which prove that the sun's beams, in some cases, favour the action of oxygene upon, and its combination with, colouring matters; whilst in other cases, it manifestly produces opposite effects upon these matters, by decomposing or separating some of theirconstituent parts, and especially the oxygene previously united to them : and probably these are the only ways in which it affects colours; it being doubtful whether ligrtit ever unites itself so permanently to any matter as it must do, to pro- duce the lasting colours given by dying. From the experiments of Beccari, Meyer, Schulz, Scheele, and Sennebier, it appears that muriate of silver (horned silver), which is nearly of a pearl white, changes to a violet co- lour, and from thence to a black, in the space of a very few minutes, when exposed to the sun's rays in a transparent glass ; and this change Sennebier ascribes solely to the action of light; since, as he maintains, the muriate of silver will invariably retain its whiteness, though ex- posed either to heat or cold ; and in a moist or a dry air, or in vacuo, if secured from the ac- cession of light, and of what he calls phlogistic vapours (probably sulphuretted hydrogenous gas), and that it loses its whiteness only by the application of light, and then only in propor- # • 40 PHILOSOPHY OF tion to its quantity or intensity ; so that when the sun's rays are copiously applied by a lens, the muriate of silver is rendered violet coloured in a single second. By covering the muriate of silver with four thicknesses of white paper, its whiteness was preserved ; one, two, and three thicknesses retarded, but did not prevent its finally becoming violet and black. Mr.Sennebier found that the different rays of light, under the same circumstances, coloured the muriate of silver with different degrees of celerity; i.e. the violet rays in 15 seconds, the purple in 23 se- conds, the blue in 29, the green in 37, the yellow in 5 minutes and 30 seconds, the orange in VI minutes, and the red in 20; but the rays of the three last colours would not, as he re- lates, produce such a dark violet colour in any length of time, as was thus quickly produced by the more refrangible rays.* I have also wit- nessed some of these, and other changes of colour, taking place in miniated or horned silver, which manifestly result from an inci- pient reduction or revival of the metal, and with it a production of the dark colours which silver always manifests in that state ; and in confir- * These facts which formerly appeared unaccountable and extraordinary, may now be readily explained by those which Mr. Herschell subsequently discovered and published (i. e. in 1800) respecting the composition of the sun's beams, and the very different powers of their several constituent rays. PERMANENT COLOURS. 41 mation of this, I need only mention what I have several times observed, that though muriated silver, placed at the bottom of a colourless glass vessel, nearly filled with water, was made violet coloured in about two minutes, by the weak light of a room, having a single window only, and in a cloudy day ; yet a direct application of the sun's rays for many days produced no change of colour, when the muriated silver was covered with muriatic acid instead of water; a revival of the silver not taking place, whilst so much uncombined muriatic acid remained in contact with it. A solution of silver in the nitric acid likewise changes colour by the action of light, and be- comes black thereby, as well as by the applica- tion of inflammable substances, of calcareous earth, and every thing which separates a suffi- cient portion of the oxygene. It also gives the skin a black colour, which cannot be effaced, but by a removal or change of the skin itself : it tinges the hair, nails, and other animal substances, in like manner, because they occasion a separation of so much of the oxygene as is necessary for that purpose- Mercury dissolved in nitric acid, being washed with water, affords a yellow oxide, which, when exposed to the light in a transparent colourless glass vessel, will become black on thesidc to which the light is appljed,even where the vessel is filled 42 PHILOSOPHY OF with water; because the light extricates a part of the oxygene; this yellowoxidebeingapreparation of mercury, with but a very small proportion of acid. The red precipitate, and several other pre- parations of mercury, have their colours changed even under water, by similar means. The white or colourless solution of mercury, by the nitric acid, when applied to animal and inflammable substances, tinges them purple and black, in the same way, and from the same cause, as they are tinged by the solution of silver. Similar effects happen with the solution and oxide of bismuth, which last is therefore used to blacken hair when mixed with pomatum. Almost all the other metals afford instances of changes of colour more or less remarkable, depending both upon the accession and the separation of oxy- gene; and in many of these light has a consider- able influence in promoting one or other of these effects. In all the instances lately mentioned, black- ness was produced by a separation of vital air from the metallic basis; but there are others in which it results from the addition or accession thereof. Arsenic, as Mr. Chaptal mentions, when first sublimed, is of a shining grey, or steel colour, but blackens speedily by exposure to the air (" noircit promptement a l'air;") and he likewise observes, that " man- ganese, precipitated by an alkali from its solu- tion, was found to be a whitish gelatinous PERMANENT COLOURS. 48 substance, which soon changed colour, and became black, by the contact of air; that, hav- ing been a witness of this phenomenon, lie could only attribute it to the absorption of oxygen- ous gas, and found this to be the case, by shak- ing the white precipitate in glasses filled with that gas, by which the black colour manifested itself in one or two minutes, and a considerable part of the gas was found to have been absorb- ed." Elemens de Chymie, torn. ii. p. 260. The preceding instances relate to mineral and inorganical substances ; there are many, how- ever, which relate to the colours of vegetable and animal matters. Ray, in his Historia Plantarum, printed in 1686, vol. i. p. 15, appears to have discovered, by several experiments and observations, that the green colour of plants depended chiefly upon the influence of light: he had found that they were green, whilst vege- tating under a transparent glass bell exposed to the light, and that when growing in obscurity under an opaque vessel, they lost their green, and acquired a pale whitish yellow; their stalks, at the same time, becoming long, slender, and feeble, and their leaves small. And these effects he ascribed to the want of light, rather than of either air or heat. " Nobis tamen non tarn aer quam lumen, luminisve actio colons in planta- rum foliis viridis caussa esse videtur." — " Ad hunc autem colorem indueendum non requiritur H9 ■ 44 PHILOSOPHY OF calor," &c. Mr. Bonnet has since confirmed Hay's conclusions upon this subject, and added several curious facts, resulting from a variety of experiments related in the fourth and fifth vo- lumes of his -works : but it is Mr. Sennebier who lias done most, and carried his inquiries farthest respecting it, as appears by his " Mem oi res Phy- sico-Chymiques sur l'lnfluence de la Lumiere Solaire, &c. in 3 vols. 8vo. It is now well ascertained, that vegetables, growing in the light, give out oxygenc gas, (pure vital air;) and Dr. Ingenhouz, by a great number of experiments, has proved, or con- ceives himself to have proved, that in the dark they give out the carbonic acid gas (fixed air;) though this has been doubted by others, and particularly by Mr. Sennebier, who conceives, that, in these cases, it was the' pure air vitiated by some disease or decomposition of the plant itself: Dr. Ingenhouz, however, in his last pub- lication, adheres to his former opinion, and sup- ports it with new facts and arguments. Be this, however, right or wrong, there is no room to doubt but that healthy plants, growing in the solar light, decompose both water and car- bonic acid gas ; and, appropriating to themselves the hydrogene, or inflammable air (which is a constituent part of water), and the carbona- ceous matter, or basis of the carbonic acid, with perhaps a small portion of the oxygenc, they PERMANENT COLOURS. 43. emit the rest in the form of vital air, which the light seems to separate, by combining with and rendering it elastic, in the same manner as it separates the oxygene from the calces or oxides of metals, &c. But when plants vegetate in obscurity, no such separation can take place: indeed, the water imbibed by the plants seems not to be properly decomposed, unless their liv- ing powers be aided by the stimulus of light, and by its affinity for the oxygene. There is, there- fore, an accumulation of this latter substance, and a want of inflammable air to compose the resinous matter, by which the green colour of the plant is produced ; and this colouring mat- ter being very sparingly formed, and at the same time combined with an excess of oxygene, the plant, instead of its natural greenness, exhibits only a white or pale straw colour. Mr. Senne- bier found that plants, in this state, received a deeper green, and in less time, by exposure to the violet rays of light, than to those which were less refrangible, as was the case in colouring: the muriate of silver. lie also found that plants left to vegetate without light, under vessels filled either with nitrogene, or hydrogenc, did not lose their green colour, as when surrounded by common atmospheric air. In carbonic acid gas they soon perished. Dr. Ingenhouz also observed, that on mixing a little hydrogene with either the common or the vital air in which a ■H 46 PHILOSOPHY OF plant was growing, under a transparent glass, the green colour of the plant soon became deeper. In these cases there seems to have been an ab- sorption of the hydrogene, affording an increase of the resinous colouring matter. Mr. Sennebier also found, that the red tinc- tures of orcanette,* safflower, kermes, gum lac, and cochineal, were made yellow by exposure to the sun's rays ; and the tincture of dragon's blood was thereby deprived of all colour : in these cases the alcohol, or spirits of wine, assisted the action of the sun's rays in decomposing the several colouring matters, probably by abstract- ing and combining with their oxygene ; because it was found that the aqueous infusions of orca- nette, kermes, and cochineal, suffered no change by the like exposure; though indeed the infu- sions of safflower, dragon's blood, and gum lac, were changed by it ; perhaps because they contain a resinous matter which might have co-operated with the rays of light, in the same way as the spirit of wine is supposed to have done. Mr. Sennebier observed, that the petals of damask roses afforded a kind of brick colour to spirits of wine, when put into it; and that this, by a few minutes exposure to the common light, became of a fine violet-colour; which, however, was soon destroyed, by a direct application of the * Anchusa tincloria. Lin. • PERMANENT COLOURS. 47 sun's light, unless when a few drops of some of the strong acids were added; in which case, the colour withstood the sun's rays for several months. From these instances I conclude, that the colour of roses depends on a certain propor- tion of oxygene ; that the light, aided by the affinity of the spirits of wine, for oxygene, produces a separation of it, and destroys the colour; but that these effects are obviated, as might be expected, by the addition of acids containing and affording a supply of oxygene. And that this was the fact, seems evident from this observation, made by Mr. Sennebier, that when the petals of the roses had been rendered white, by imparting their colour to the spirit of wine, they regained it on being taken out, and exposed to the air, even in a dark place; though they did it much quicker in the light; but not at all in a vessel containing only nitrogene surround- ed by quicksilver, even when aided by an imme- diate application of the sun's light ; which clearly proves, that the restitution of oxygene was indis- pensably necessary to the restitution of their colour. In the same way sulpl/weous acid whitens roses, by depriving them of their oxygene; and the sul- phuric acid revives the colour, by restoring it.* * The sulphureous or volatile vitriolic acid, not being saturated with oxygene, is disposed to attract it from other matters in contact with it ; and by so doing, it not only whitens roses, but silk, wool, and other substances, rendered yellow by being united to a certain portion of oxygene. . 48 PHILOSOPHY OF Mr. Sciinebicr also found that the red skins of peaches became white in spirits of wine, like the petals of roses, and, like them, regained their colour by exposure to the air; as did also the red skins of plumbs. He likewise observed, that the water-colours used by painters, if covered by a solution of fish-srlue or isinglass, and then var- nished, withstood the action of the sun's rays much longer than if varnished without the fish- glue ; which last seems to have prevented the varnish from co-operating with the light in extricating the oxygene of the colouring matters, as, from its inflammable nature, it would do, if in immediate contact with them. Negro chil- dren when first born are white, as plants are when they first shoot above the earth, though they become black in a few days, after being exposed to the light, as plants become green, and probably from the same cause. In like manner the hair of such kittens, puppies, &c. as are intended by nature to become decidedly black, is immediately after birth only of a brownish black ; but it gradually darkens externally. Though the hair of the blackest cats and dogs will be found, even in old age, not to be black at the roots near the skin, where it is most secluded from the light. Mr. Sennebier mentions, upon the authority of Scheele, that the Nereis lacustris, is red whilst living in places accessible to the sun's rays,, and 460 PHILOSOPHY OF lent effects ; an operation which, after I had at first accidentally succeeded in performing it, I found liable to so many failures, from the dificulty of ascertaining, at any time, how much of the metal had been actually dissolved, that I have long ceased to expect that it can ever be adopted with advan- tage by dyers.* I have mentioned, at p. 305 of my first vo- lume, that a fine lasting black, without iron or any other basis might be dyed upon blue cloth, from a species of lichen, called rags, or stone rag in the North of England, (the lichenoides pulmo- nium reticulatam vulgare marginibus peltiferis, of Dillenius) ; and if this could be readily and co- piously obtained it would, probably, deserve to be preferred to madder and weld for rendering blue cloth black ; and, indeed, I have found, that the brownish yellow which alder bark affords upon the aluminous basis, may, for this purpose, be advanta- geously substituted for that of weld. * The best, and, perhaps, only method of doing this, would be first to ascertain, as nearly as possible, the quantity of iron in its metallic state, which will produce the best erFects when totally dissolved by, or with the soluble part of a given quantity of galls j but it would be highly inconvenient, and, in several respects, disadvantageous, to wait long enough for this conplete dissolution of the iron, unless it were first brought into the state of nonfilings 5 which, for general use in dyeing bJack, would be attended with more trouble andexpence, than any ad- vantage to be expected from this change seems likely to be com- pensate. PERMANENT COLOURS. 4G1 Of the Application of the Black Dye to Silk. The fibres of silk not being organized like those of wool, do not so readily admit the black dye as the latter. Dr. Lewis (in his Philosophical Com- merce of Arts) observes, that " woollen and silk are both dyed of a permanent deep black, but with this difference, that what the woollen dyer effects by three or four dippings of the cloth, in his dyeing liquor, the silk dyer scarcely obtains from twenty or thirty dips." Though raw silk imbibes the black dye with as much facility as that which has been deprived of its gum, yet, when dyed, the black appears less intense and less fixed in the former than in the latter ; and it is, therefore, made previously to un- dergo the usual boilinsr, with one-fourth or one- fifth its weight of soap, during three or four hours : by this operation, indeed, silk often loses nearly one-fourth of its weight, but this loss is more than compensated by that which it gains from the black dye. As the affinity of silk with the soluble parts of trails is greater than with the iron contained in a solution of the sulphate of that metal, it is thought most advantageous to begin by first ap- plying the former ; and for this purpose about one-half as much in weight of Aleppo galls as of fhe silk to be dyed, is boiled in a suitable pro- .portiori of water, three or four hours, after PERMANENT COLOURS. 49 white when living in obscurity ; and M. Dorthes asserts, (Ann. de Chymie, torn. ii«) that most of the larva of insects, inhabiting the dark cavi- ties of animals, trees, fruit, &c. are white; and that having forced a variety of them to live under transparent glasses, exposed to the light, they gradually became brown. But the most decisive and interesting proof of the action of light, in producing various colours by promoting a separation of oxygene from animal colouring matter, will be found by the effects which I shall notice hereafter, when treating of the celebrated purple of the ancients. The preceding are examples of animal and vegetable colours produced, changed, or destroyed, either by the action, or the want of light, ex- erted in separating their oxygene. In many other cases, however, the affinity of light is very differently exerted, upon colouring mat- ters, by promoting a combination of oxygene with them. The green colour of the leaves of plants resides in a resinous substance, which being dis- solved and extracted by spirit of wine, produces a green tincture ; and Mr. Sennebier having exposed this to the rays of the sun, in a clear transparent glass, but half filled, he found, upon repeated trials, that the colour was generally destroyed in about twenty minutes, and a yel- lowish substance was precipated to the bottom ; E 50 PHILOSOPHY OF which seems to have been the colouring matter saturated with oxy gene : but when the glass was completely filled with the green tinc- ture, and closely stopped, he found, that the strongest action of the sun's rays upon it, during four months, did not weaken in any degree, the green colour, because all oxygene was excluded, and the rays of light, without it, were unable to effect any change. When nitro- gene was inclosed in a vessel partly filled with this green tincture, the latter suffered little or no change, by long exposure to the direct action of the sun's light ; but if, instead of this, he substituted pure vital air, the green colour was most rapidly destroyed. Mr. Sennebier also found, that the dark red juice of black cherries very soon lost its colour, when exposed to the sun's rays, but that a tincture of those cherries- in spirit of wine, preserved its colour in the same circumstances ; the spirit of wine, as I conceive, affording a covering and defence to the colouring matter of the cherries, against the action and farther combination of oxygene or vital air. Here the effect was directly opposite to that with roses, lately mentioned. M. Fabroni has also asserted, (Ann de Chemie, torn, xxv.) that the fresh juice of the aloe succotrina angusti folia, by mere exposure to the atmosphere, either with or without the contact of light, soon became red, first, at the parts most accessible t© PERMANENT COLOURS. 51 the air, and afterwards in other parts, and that it finally became of a very dark, but very lively purple : and he convinced himself that this change resulted exclusively from an absorption and combination of oxygene. There are many other instances of changes of colour bv an absorption of oxygene, with or without the assistance of light ; and in particular two expe- riments made by M. Berthollet. In the first, he " inverted, over mercury, a bottle half full of the green solution (employed by Mr. Senne- bier,) and exposed it to the light of the sun ; and when the colour was discharged, the mer- cury was found to have risen in the bottle, and consequently vital air must have been absorbed ; the oxygene having united with the colouring matter." In the second experiment, he " placed a tincture of turnsol, in contact with vital air, over mercury, in the dark, and he also exposed a similar tincture to the light of the sun; the former continued unchanged for a considerable length of time, and the vital air had suffered no diminution; but the latter had lost much of its colour, was become red, and the air was in a great measure absorbed," &c. M. Fourcroy has also demonstrated, (see Ann. de Chimie. torn, v.) that a variety of colouring matters, extracted by water, and left exposed to the air, combined with its oxygene, and thereby not only assumed new colours, but e 2 52 PHILOSOPHY OF became much more fixed and permanent ; which happens likewise in the production of indigo, as will be proved hereafter. I have now noticed the principal facts re- specting the powerful agencies of solar light, in producing, changing, and destroying mineral, vegetable, and animal colours ; which agencies as far as we know, or can judge, seem to be principally, if not exclusively, exerted, in promoting, under particular circumstances, and with particular coloured, or colouring, matters, an abstraction or diminution of their oxygene; and with other matters and other circumstances, in causing a new or additional combination of it. These opposite effects, may be now explained in consequence of recent discoveries respecting the sun's beams. Newton taught us, that when the rays of which they consist are transmitted through a triangular prism, and received upon white paper, those most distinctly perceptible, are the red, orange, yellow, green, blue, indigo, and violet; and that if the coloured image or spectrum be divided into 360 parts, the reel will occupy 45 of these parts, the orange 27, the yellow 48, the green 60, the blue 60, the indigo 4.0, and the violet 80; and that the red are refracted the least ; the violet the most ; and the other rays inversely in the order in which they have been arranged, and he supposed them to vary in the size of their particles, according to PERMANENT COLOURS. f>3 this order ; those of the violet being the smallest. It has, however, been recently ascertained by Dr. Herschell ; (see Philosoph. Transactions for 1800, p. 267.) and by the experiments of Sir H. Englefield and others, that the solar beams comprehend three sorts of rays ; viz. one which excite heat and promote oxidation, or the combination of oxygene with different matters; another which illuminate; and a third which deoxidize, or cause the sepa- ration of oxygene. He found the yellow, and the pale green rays, to possess the greatest power of illuminating, and the violet the least ; and the red rays to possess the greatest power of heating, and the violet the least. But beyond the red rays, there are certain invisible heating rays, which raise the thermometer higher than even the red rays. Moreover, at the other extremity, a little beyond the violet rays, not only the thermometer is not affected, but there are there, certain other invisible rays, which produce, very efficaciously, particular che- mical effects ; one of which is that of changing from white to black, the colour of a precipite of the muriate of the silver just made. This is, in- deed, done most rapidly, by the collected rays of the sun's beams, but the separate rays do it with greater energy, in proportion as they are nearest to the invisible rays, at the violet extremity. Sir H. Davy, also states, that " if moist horned silver, 54 PHILOSOPHY OF (muriate of silver) be exposed to the different rays of the prismatic spectrum, it will be found that no effect is produced upon it by the least refrangible rays, which occasion the greatest heat, without light ; a slight discolouration only, will be occasioned by the red rays ; the effect of blackening, will be greatest towards the violet part of the spectrum ; and in a space beyond the violet, where there is no sensible heat or light, the chemical effect will be very distinct.'* " This observation, (he adds) made by M. Ritter and Dr. Wollaston, proves that there are rays more refrangible than the rays producing light and heat; and from the observations of M. Berthollet, it appears that muriatic acid gas is formed, when horn silver is blackened by light, so that they may be called hydroge?iating rays," p. 21 1. Sir H. Davy farther observes, in the next page, that he " found that the puce (or Flea) coloured oxide of lead when moisten- ed, gradually gained a tint of red in the least re- frangible rays, and at last became black, but was not affected in the most refrangible rays • and the same change was produced, by exposing it to a current of ,>droge,ne gas. The oxide of mercury procured by a solution of potassa and calomel, exposed to the spectrum, was not changed in the most refrangible rays, but became red in the least refrangible rays, which PERMANENT COLOURS. 55 must have depended upon its absorbing oxy- gene." Dr. Wollaston found that the substance called gum-guaiacum, when exposed in the most refran- gible rays, beyond the violet extremity, was changed from its yellowish colour to green; and that it was again made yellow, by the least refrangible rays. One of which effects must have resulted from a separation, and the other from an absorption of oxygene. The oxygenating power of the solar rays is, however, that which M. Berthollet seems exclusively, and as I think erroneously, to insist upon, as occasioning, either "with or without the aid of light, all the changes and injuries to which animal and vegetable colouring matters are liable ; and he deems the action and effects of oxygene in these cases to be similar to those of combustion* " In con- sidering the effects of air on colours (says he,) it is necessary to make a distinction between those produced by metallic oxides, and those produced by the colouring particles," meaning those of an animal or a vegetable nature ; the " * Cet effet doit etre considere comme une veritable com- bustion. Par la\ le charbon qui entre dans la composition des parties colorantes, devient predominant, and la couleur passe ordinaircment an jaune, au fauve, au brum ou cette degradation en s'alliant avec ce qui reste de la premiere couleur, produit d'autres apparences." 56 PHILOSOPHY OF modifications of the former are, says he, " entirely owing to different proportions of oxygene ;" but I have been led by observation, lie adds, " to form a different opinion of the latter;" meaning those with which the oxy-muri- atic acid had exhibited different phenomena, sometimes discharging their colour, and producing whiteness, but most frequently rendering them yellow, fawn, or root-coloured, or brown or black, according to the intensity of its action : and he remarks, that he had found, by com- parison, that when the colouring particles were rendered yellow, fawn-coloured, or brown, by the oxy-muriatic acid, effects were produced similar to those of combustion ; and that they were "owing to the destruction of thehydrogene; which, as it combines with oxygene more easily, and at a lower temperature than charcoal does, leaves the latter predominant ; so that the na- tural colour of charcoal is more or less blended with that which before existed ;"* and as * Messrs. Lavoisier, Bertholiet, and other pneumatic chy- mists, have considered the black colour of charcoal as natu- rally existing in the vegetable matter from which it is formed, and not as the result or effect of combustion. To me, however, charcoal seems to be a kind of vegetable oxide, consisting of the carbonaceous basis, united to a certain portion of oxygene, enough to render this basis black (as it occasions the blackness of manganese,) but not enough to saturate and convert it into carbonic acid gas. Hard woods contain so great a portion of PERMANENT COLOURS. 57 u the light of the sun considerably accelerates the destruction of colours," he concludes that the basis of charcoal, that if it really existed therein, with its black colour, previous to combustion, it is impossible to con- ceive how they should ever appear white, yellow, red, &c. since in dying, &c. we find, that laying other colours upon a black ground, increases the blackness. Neither do I think that this blackness is the only circumstance in which charcoal differs from its basis, or the state in which the vege- table part thereof existed previous to combustion : on the con- trary, its oxidation, or combination with oxygene, manifestly gives it new and very remarkable properties. This basis, is, indeed, never converted into charcoal, but by such a degree of heat, and in such circumstances as must necessarily occasion its combination with oxygene ; and when this conversion is made, the charcoal is rendered infinitely more indestructible than any other vegetable matter, as it will resist thp combined action of «un, air, moisture, &c. for hundreds of years ; and indeed it can hardly be destroyed, but by such farther combustion and combination with oxygene, as will change it into carbonic acid gas. This indestructability, or stability, as well as the black colour, of charcoal, therefore manifestly result from the combi- nation of oxygene with its basis. Did it really exist, with its black colour naturally in wood and other vegetables, why do we not find it remaining intire after the other parts of vegetables 2re separated or destroyed by fermentation, putrefaction, &c. ? And why does it decay and rot with them undistinguished, con- trary to what happens when it occurs separately, in the form of charcoal ? And why, when it has assumed this form, will it not recombine with matters similar to these which were sepa- rated from it, and enter with them into fermentation, &c. as it surely ought to do, if it had acquired no new property, and only been left in a distinct form, by the simple abstraction of those matters. The preceding observations respecting charcoal, were ob PHILOSOPHY OF it ought, if his theory be well founded, " to favour the combination of oxygene, and the combustion thereby produced."* first printed in (be year 1793. It did not then accord with my purpose, to enter upon a minute examination of the several constituent parts of charcoal ; I wished only to convince my readers that it was not a simple substance, naturally formed, and existing with its black colour in vegetable matters ; and that when dyed colours faded, and became brown or dark coloured, by exposure to the sun and air, this change did not happen, as M. Berthollet had conceived, because the supposed naturally black colour of the charcoal, contained in the vegetable dyes, was rendered visible, and predominant, by a separation of the other matters, which had been in union with it, (" de sorte que la couleur propre au charbon, se mele plus ou moins, a celle qui preexistait." Berthollet, torn. i. p. 133). To produce this conviction, I thought it only necessary that my readers should, without bias, exercise their senses and under- standings. Since that time, the nature and composition of charcoal have been nearly ascertained ; but I think I may claim the merit of having first occasioned a distrust of the doctrine of M. Lavoisier on this subject, and thereby pro- moted the subsequent experiments and inquiries. Dr. Thompson, one of our best systematic chymical writers, makes the following observation in the first volume of his system of chemistry, viz. " Lavoisier supposed pure charcoal to be a simple substance, and for that reason invented the term carbon to distinguish it. But other philosophers were of opi- nion that charcoal is a compound body, and that it is composed of carbon and oxygene. The truth of this opinion, which, as far as I know, was Jirst maintained by Dr. Bancroft, has been lately established by the experiments of M. Guy ton Morveau." To these have been more recently added, the accurate re- 6earch.es of Messrs. Allen and Pepys. * Elements of the Art of Dying, chap. iii. PERMANENT COLOURS. 59 In thus ascribing the decays of vegetable and animal colouring matters generally, to effects or changes similar to those of combustion, M. 13er- thollet has, I think, gone farther than is war- rantable by facts. It cannot, I am persuaded, be his intention that we should apply the term of combustion to alterations which result from a simple addition of oxygene to colouring mat- ters, without any destruction or decomposition of their constituent parts ; though a great many of the alterations and extinctions of these co- lours evidently arise only from such simple additions. The nitric, sulphuric, and other acids containing oxygene, have the power not only of weakening, but of rendering latent for a time, the colours of many tingent matters ; not however by any effect which can properly be denominated a combustion, but rather by a change in their several affinities or attractions, for particular rays of light in preference to other rays; but none of their parts being destroyed, or carried away, the addition of an alkali, or of a calcareous carbonate, will generally undo such alteration, and restore the original colour, by decomposing and neutralizing the acid or oxygene which had caused the alteration. Of this numerous instances might be given ; it will however be sufficient to mention, what most people have seen, that ink, dropped into a glass 60 PHILOSOPHY OF of diluted nitric, or vitriolic acid, will lose its colour, and that it may be again restored by adding a suitable portion of vegetable or fossil alkali ; and that this may be done several times with the same ink, and therefore the change, or loss of colour, could not have been the effect of combustion. The production and existence of each particular colour, depends upon pre- cise, and often very minute proportions of the constituent parts of the colouring matter, and it may, therefore, be changed, and in many cases even destroyed, by every thing capable of alter- ing these precise proportions ; and as this may be done by very opposite causes, we are not war- ranted in ascribing the decays of colours gene- rally to combustion only, or indeed to any one cause exclusively. Many colours are as much injured by muriatic acid, as by the sulphuric or nitric : and as the former is now generally ad- mitted to contain no oxygene, or to contain it so inseparably oombined, that no combustion can take place by means thereof, we must necessa- rily infer, that the effects of the muriatic acid, are not occasioned by combustion, which muria- tic acid does not produce. Mr. Scnnebier exposed a great variety of woods to the action of the sun and air, and found all their colours very soon affected. The white woods were generally made brown, and the red and violet changed either to yelloxc or black. PERMANENT COLOURS. 61 Guciacum was rendered green ; the oak and the cedar were whitened, as were the brown woods generally ; several of these effects, and espe- cially the whitening, do not resemble those of combustion, any more than the bleaching of wax and talloxv, by exposure to atmospheric air. The colour of each particular substance re suits from its peculiar constitution, pro- ducing in it a particular affinity or attraction for certain rays of light, and a disposition to reflect or transmit certain other rays ; and ia this respect it may doubtless suffer very consider- able changes, without any effects similar to those of combustion. And indeed the changes of colour which arise from the access of vital or atmospheric air, seldom resemble those which the mere predominence of blackness (the sup- posed natural colour of charcoal) would pro- duce ; though this may have been the case with the colouring matter of brown or unbleached linen, upon which M. Berthollet's experiments were principally made. But whether the action of vital air, or its basis, in promoting the decays of a few parti- cular colours, ought to be denominated a com- bustion or not, I am confident that, at least, some others are liable to be impaired, not so much by an accession of oxygene, as by the loss of it ; an effect, of which I have already enumerated several examples, among animal and vegetable, 62 PHILOSOPHY OF as well as mineral substances, deriving their colours from a combination with certain por- tions of oxygene ; and of these I might easily augment the number. Hook and Lower long since noticed the dif- ference of colour in arterial and venal blood; and it has been since proved, by numerous expe- riments, that the tine vermilion colour of the former, is produced solely by vital air, which it is capable of acquiring even through blad- ders, the coats of blood vessels, &c. And very recently, Mr. Hassenfratz seems to have proved (see Ann. de Cbimie. torn, ix.), that as this fine red colour is gained by a dissolution of oxygene in the arterial blood, so it is lost, and the dark colour of the venal blood restored, by a separa- tion of the oxygene. That the blue colour of indigo absolutely de- pends upon a certain portion of oxygene, has been already mentioned, and I shall hereafter give some curious illustrations of this fact, from which it will appear that a solution of indigo, by losing its oxygene, may be rendered as pellucid, and, excepting a very slight straw- coloured tinge, as colourless as water, and that it will afterwards speedily return, through all the shades of yellow and green, to its original deep blue, only by exposure to atmospheric or vital air. Similar to this is the fact long since observed by the Abbe Nollet, of the tincture of PERMANENT COLOURS. CS archil (orchella) employed to colour the spirit of wine used in thermometers, which after some time loses its purple colour, but soon recovers it again upon being exposed to atmospheric air. And this also happens to the infusion of turnsol, and to syrup of violets, which both lose their colours when secluded from air, and regain them when placed in contact with it.* Many other examples of the like effects might be mentioned here ; but to avoid repetitions, I beg leave to refer my readers to subsequent parts of this work, in which I shall have occasion to instance various animal and vegetable colours, produced solely by the contact of vital or at- mospheric air; and some others, which, when given by dying or calico printing to wool, silk, cotton, &c. though unable to sustain a single day's exposure to the sun and air without mani- fest injury, were found to receive none from the action of acids of considerable strength, but, on the contrary, were in some degree preserved by being wetted with them, and especially with the citric acid. But the same colours, if covered with linseed oil, were found to decay more quickly from exposure to the sun and air, than if uncovered. These * Oxygene is also absolutely necessary to produce the blue colour of Prussian blue, and the black colour of ink. These facts are too notorious to require proof. 64 PHILOSOPHY OF colours therefore could not owe their decays to the contact or combination of oxygene, because they were not only unhurt, but benefited by its agency in the citric, and otheracids containing it; and also because they were soonest impaired when secluded from it by a covering of linseed oil. Probably the decay of these colours was occasioned by a loss of at least some part of the oxygene, necessary to their existence, and which the linseed oil assisted in depriving them of, by its known affinity therewith. In forming systems, we are apt to draw gene- ral conclusions from partial views of facts. And this even, M. Berthollet seems to have done, not only in ascribing the decays of vegetable and animal colours, exclusively to effects similar to those of combustion, but also in representing the oxy-muriatic acid as an accurate test or measure for anticipating, in a few minutes, the changes which these colours are liable to suffer, by long exposure to the action of sun and air ; for though it should be true that the oxygenated muriatic acid, in wcakeningor destroying colours, gives up to them more or less of the oxygene, which it is supposed to have received from manga- nese; and that, by this new combination of oxy- gene, those affinities for particular rays of light upon which their colours depend, are liable to be destroyed ; it is nevertheless true, that the changes of colour so produced are no certain indication of PERMANENT COLOURS. those which the combined influence of light and air will occasion upon colours in general ; there being, as I have already observed, andkas I shall more fully explain hereafter, several colours which are very speedily destroyed by the latter of these causes, though they resist the action of the oxy-muriatic acid, even longer than the best colours given to printed calicos. M. Berthollet well knows, since nobody has contributed more to ascertain, how much the properties of oxygene are diversified by each particular basis to which it unites ; and it does not therefore seem warrantable to imagine, that its action would not be modijied, as well as in- creased, by a basis so powerful as that of the common muriatic acid; or that the united pro- perties of both, should exactly represent or re- semble those of atmospheric air upon colours, any more than they do in the lungs, wiiere, instead of supporting life, when respired, they would instantly destroy it. Ten years after I had published the preceding observations, M. Berthollet, in the new edition of his " E16mens de Teinture," (between pages 131 and 147 of the first volume) recapitulated those parts of his former edition, which relate to this subject; and for doing so, he assigned the following motive, viz. parceque Bancroft, dont Fautoriti est pour nous dun grand poids, a pr6tendu reYuter la theorie qui y est 6tablie, p 66 PHILOSOPHY OF ct que nous desirons de mettre en etat de peser ses raisons, et les motifs de notre opinion." He afterwards (p. 147 and seq.) notices some of my objections to his theory ; and particularly that wherein I asserted, that colouring matters suffer, by the action of acids, and other sub- stances, alterations which cannot be compared to combustion ; to which he answers, " mais il n'est question dans les explications precedentes, que de l'espece d'alteration qui depend de Tac- tion de l'oxigene." This answer, were I not fully convinced of M. Berthollet's perfect candour and regard for truth, would seem to be either an evasion, or a mere petitio principii : and it certainly has the effect, of at least greatly narrowing the ground of our dispute ; for I have never contended that oxygenc assisted by light, does not in some cases injure colours in the way which M. Berthollet supposes, i. e. by combining with the hydrogene of the colouring matter, &c. ; though I have objected to what seems to have been his opinion, that this was the only way in which the fading or decaying of colours ought to be explained ; and consider- ing the very opposite effects of light in regard to oxygene, which have been recently stated (and which M. Berthollet seems to have over- looked) it is impossible for me not to persist in that objection. It therefore still remains for us to ascertain, and distinguish the particular cases in PERMANENT COLOURS. fi7 which oxygen e, assisted hy light, injures co- lours, by combining with the hydrogenfe of their respective colouring matters ; but even if this were done, I should never be convinced that these matters had naturally contained ready formed black charcoal, and that the degradation of the faded or injured colour, resulted from a greater manifestation and predominance of this charcoal, with its supposed naturally black co- lour. M. Berthollet next adverts to my objection that oxygene, far from destroying colours gene- rally, is necessary to the existence of some of them, as e. g. of indigo. And to this he answers, " n'est-ce pas ce que Ton a dit ? mais Ton a dis- tingue^ les cas ou ildevientun element de la cou* leur, et ceux ou son action devient destructive." An answer which leaves us still to ascertain and distinguish the numerous colouring matters, of which oxygene is admitted to be an essential constituent, and which, from that cir- cumstance, will be most susceptible of being injured, by a deprivation of oxygene, rather than by any addition of it ; and even after this distinction shall have been made, it will not fol- low, as a necessary consequence, that the other remaining colours are not liable to suffer by effects very different from those of combustion. Next in order, M. Berthollet notices my ob- jection to his ascribing the degradation of faded F 2 68 PHILOSOPHY OF colours, to a predominance of charcoal, since many substances contain large proportions of it, without having any such colour as has been ascribed to its excess; and since the colour of charcoal itself, results only from an oxygenation of its basis. To this he answers, that without entering upon a discussion of my opinion on this point, " il s agit seulement de scavoir, si dans les circonstances dont il est ques- tion, le changement de couleur n'a pas de Tanalogie avec celui que l'on observe, lorsque Ton distille une substance veg^tale :" and he seems to imagine (erroneously) that I had conceived the free access of the oxygene of the atmosphere, to be necessary to the browning of vegetable mat- ter in that process, where there is otherwise, a sufficiency of oxygene. He next observes, that I had erred in supposing that his opinion was founded solely upon experiments made with the brown colouring matter of unbleached linen. But it will have been seen, that I only mentioned this as the matter upon which they " zvere prin- cipally ??iade" And, finally, in regard to my objection to his assuming the action of the oxy- muriatic acid upon dyed colours, to be an exact indication and measure of that which they would suffer by ex- posure to the sun and air, he observes that he did not find in my work, an account of the ex- periments which I had announced, as suffi l'ent PERMANENT COLOURS. 60 to prove that the effects of the oxy-muriatic acid, are sometimes at variance with those of theoxy- gcne of the atmosphere. For this last obser- vation there may have been some little founda- tion ; but my readers will soon find it removed. 1 had, indeed, occasionally noticed some of these experiments, though not collectively ; and others were intended to be also mentioned occasionally, in the second volume. M. Berthollet next admits, that in comparing the effects of the oxy-muriatic acid, with those of the oxygeneof the atmosphere, it is necessary to take into consideration the greater condensa- tion of the oxygene in the former, together with " L action particulilre deV acide Muriatique ;'* which, to my understanding, he certainly did not do in regard to the latter ; and his not doing it, was the chief foundation of my objection. Even in his last edition (torn. i. p. 68) when treating of these effects, of the oxy-muriatic acid upon colours, he says " il agit a\ors par Tovi- genc qu'il abandojine, et par consequent son action rie differc que par fintensitc, de celle de Fair atmus- pherique ;" so that even in this last edition, the particular action of the muriatic acid is com- pletely, and as M. Berthollet now admits, impro- perly overlooked. He admits also, at p. 149, that it is necessary to distinguish between the effects produced by the oxy-muriatic acid, wi;e:i it completely discharges or extinguishes' all colour , 70 PHILOSOPHY OF and those due to the combination of its oxygene, with the hydrogene pf the colouring matters, I do not, however, believe, that there is any such difference in its action, or that it ever relin- quishes any oxygene to combine with the hy- drogene of the colouring matter in question ; but that it destroys colours, b\ a power pecu- liar to itself, and inexplicable b} r any of its sen- sible qualities ; a power manifested by effects the very reverse of combustion, since that highly combustible substance cotton, is bleached and rendered perfectly white by it, instead of being made brown or black, as it would be, if its mode of action were such as is here supposed. M. Berthollet afterwards brings this discus- sion to a conclusion, by the following partial concession, at p. 150, viz. " Si nous avons cm pouvoir refuter les ob- jections de Bancroft, sur la cause au moins la plus ordinaire de la degradation des couleurs par fair et la lumiere,nous convenons que les con- sequences de l'opinion. que nous tactions de maintenir, riauraient pas du itre it endues aux pkenomc/ies que nous allons examiner, quoiqu'on ne l'eut fait qu'avec beaucoup de reserve, et sans sortir des bornes d'une simple conjecture :'' and he then proceeds to an examination of the phenomena, to which his doctrine on this subject ought not to have been extended. Of these, the principal relates to the yellow PERMANENT COLOURS. 71 colour produced upon wool, silk, and other animal substances, by the nitric acid ; of which I have already given what appears to be the only true explanation at p. 37- If I have sometimes thought it my duty to contest the opinions of M. Berthollet, 1 have always done it reluctantly, and I can feel no pleasure in prolonging, unnecessarily, a contro- versy with one, for whose decisions I feel so much deference, even where I believe it might be done with advantage on my side; I should, therefore, here terminate our discussion, were it not incumbent on me to state certain facts, which prove that the effects of the oxy-muriatic acid upon particular colours, are not an indica- tion or measure of those changes, which would take place in the same colours, by exposure to the sun and air; and of which facts, M. Ber- thollet complains that he did not find a state- ment in the volume formerly published. In the introductory part of my present vo- lume, I have noticed the subsisting opposite opinions, concerning the nature and constitu- tion of the substance, called acide muriatiquc oxigene\ by the French chemists, and oxy-mu- riatic acid by the British; and which Sir II. Davy has lately denominated, chlorine. M. Berthollet and others, who believe oxygene to be one of its constituent parts, suppose that in bleaching or destroying colours, it acts by giv- 72 PHILOSOPHY OF ing up to them its oxygene. Scheele had imagined that it did this, by combining with phlogiston, which was then thought to be the most important part of colouring matters ; and Davy, who like Scheele, considers his chlorine as a simple or decompounded substance, says (p. 243.) that it decomposes water by a double affinity ; " that of the hydrogene for chlorine, and that of the colouring matters for oxygene ;" to which last he ascribes, like M. Berthollet, the de- structive action of chlorine upon colours, though he derives the oxygene from a different source. But if, as is here supposed, the destruction of colours by the oxy-muriatic acid resulted solely from the oxygene, which it either relinquishes, or separates from water, its effects on colours ought to resemble those of the nitric acid, when the quantity of oxygene which they severally afford, or put into action, is the same, and the effect of each, ought to be proportioned to the degree of acidity in the destroying agent. Many experiments have, however, convinced me, that few things are more unlike, than the several effects of the oxy-muriatic, and nitric acids, upon colours given by dying, &c. A very few of these experiments will suffice. — I put into a small phial, cuttings from three skeins of cotton yarn, which had been dyed, and sent to me by M. Chaptal, before he was called from his chemical labour to those of a minister of state. PERMANENT COLOURS. 75 One of these had received the Turkey red, ano- ther the nankeen buff, from an oxide of iron, and the third a black, as I believe, from madder and galls, applied upon the basis of iron, dis- solved by the pyroligneous acid. Upon these colours I poured oxy-muriatic acid, which had been prepared by Mr. Accum, and kept secluded from light. Its acidity was so slight as to be hardly perceptible to the taste, and, I believe, it mighthave been putintotheeye, withoutcausing much pain. I found, however, that in less than two minutes, the colour of the Turkey red was much impaired, and in five, the yarn throughout the greater part of its surface had become white, without passing through any intermediate colour: and at the end of half an hour, but a very few specks of red, less than a pin's head, were perceptible. The buff colour at that time was found to have acquired a little body, and the black to have lost a little, but without ceasing to be still a good black. At the same time, I put other cuttings of the same colours into another phial, and poured upon them undiluted aqua fortis, as prepared for the scarlet dyers ; and I found that in a single minute the black which had withstood the oxy-muriatic acid, was changed to a buff colour, resulting solely from the ferruginous basis with which it had been dyed ; and that the Turkey red began to exhibit the appearance ofascarlet, inclin- 74 PHILOSOPHY OF irig to the orange; and this last, (of a lively tint,) became apparently its settled colour, at the end of an hour, when the buff, by acquiring more oxygene, was considerably raised. Here, then, was a very great diversity between the effects of the nitric and the oxy-muriatic acids, in no degree according, or proportionate to their degrees of acidity; that of the nitric acid being, I think, at least fifty, and, perhaps, one hundred times greater than that of the oxy-muriatic acid, (which being tasted, at the time when its action upon the Turkey red was strongest, and when, according to Davy's opinion, it must have already decomposed water, had not, to my taste, acquired any greater degree of acidity,) and yet the former, could only change the complection of the Turkey red to a bright orange, (probably by imparting oxygene to it) whilst the latter (not, as I conceive, by any such, or other addition, but by a complete decomposition) had at once an- nihilated all the colour, (leaving the cotton yarn white) as fast, and as far, as the decomposition took place; and this without any intermediate tint, which would not have been the case if the effect of the oxy-muriatic had, as M. Berthollct supposes, resembled combustion. And, on the other hand, the black, on which the oxy-muria- tic acid could make but a very slight impres- sion, was completely destroyed, (excepting the colour of its ferruginous basis) by the nitric acid. PERMANENT COLOURS. 75 Not unnecessarily to multiply instances of these unequal effects, I will barely mention, what will be stated more fully hereafter, that this slightly acid chlorine, or oxy-muriatic acid, was, by repeated experiments, found to produce more destructive effects on the fine purple of the Cuc- cinum lapillus, than aqua fort is, or the strong undiluted oil of vitriol. Indeed, when I con- sider how generally and how powerfully the oxy-muriatic acid destroys animal and vegetable colours, whilst, from its very slight acidity, it cannot be supposed capable of either relinquish- ing, or separating from water, any portion of oxygene at all adequate to such effects, or in any degree comparable to the oxygene of the nitric acid, (and which the latter readily gives up, without producing any equally destructive effect on colours,) it seems to me as unreason- able, to ascribe this powerful agency of the for- mer, to any portion of oxygene which it can possibly bring into action, as it would be to im- pute the death of a man, poisoned by two or three grains of the corrosive sublimate of mer- cury, to the single grain of chlorine or oxy-mu- riatic acid, which, combined with quicksilver, constitutes this sublimate. If this chlorine be, as Sir H. Davy supposes, a simple elementary substance, it must pro- duce its singularly destructive effects on colours, principally at least, by a power peculiar to it- 76 PHILOSOPHY OF self, (which probably is a decomposing power ;) and if it be, as M. Berthollet supposes, a com- pound, (of oxygene and muriatic acid) jts peculiar energies must result from its composi- tion ; from the combined agency of its consti- tuent parts, and not from the action of either separately, as lias been supposed. And it may be presumed, that the same peculiar decompo- sing power, which enables the oxy-muriatic acid to annihilate colours with such extraordinary celerity, enables it also (by decomposition) to weaken and injure the texture of wool and other animal fibres, as it is known to do, in a much greater degree than the incomparably stronger sulphuric and nitric acids. It now only remains for me to mention a few of the instances within my knowledge, proving that the action of the oxy-muriatic acid upon colours, is not an indication or measure of that which they would suffer, by exposure to the sun and air; and these instances I will select from an experiment, which was made carefully, and so recently as the 8th of July, IS 12 ; when I put into an empty, glass-stopped phial, the following colours, upon separate bits of muslin, viz. 1st. A fast madder red dyed topically, by an eminent calico printer, upon a basis, from acetate of aluniine, applied by the block. 2d. A fast yellow, dyed from weld upon the same basis, by the same calico printer. PERMANENT COLOURS. 77 3d. A fast yellow, dyed upon the same basis, from quercitron bark. 4th. A fine durable purple produced .by the colouring matter of the buccinum lapillus, of which a full account will be given in the proper place. 5th. A logwood purple produced by mixing, with a strong decoction of that wood, as much muriate of tin, as rendered the former slightly- acid, and after thickening the mixture with gum arabic, applying it in spots to muslin, which, after being properly dried, was washed with soap and water. 6th. A full bright yellow produced from a simi- lar decoction of the quercitron bark, rendered slightly acid by an admixture of nitro-muriate of tin, made with two parts of nitric, to one part of muriatic acid, gummed, and topically applied in the same manner as the logwood purple, and in like manner dried, and afterwards washed. 7th. A similar yellow made from the querci- tron bark, only substituting murio-sulphate of tin, for the nitrio-muriate. Upon these colours I poured oxy-muriatic acid, with which Mr.Accum had recently supplied me. (and which I had kept secluded from the light,) until the phial was full ; after which, in less than two minutes, I found that the bits of muslin, with the ?nadder, weld, and quercitron, colours dyed upon the almninious 78 PHILOSOPHY OF basis, were become perfectly white, by a com- plete extinction of their several colours. Whilst the logwood purple, that form the buccinum, and the quercitron yellows, with solutions of tin, were not apparently changed. But in about five minutes the logwood purple appeared to be losing body, as did the quercitron ellows soon after; and a similar effect soon became evident in the shell purple. In about fifteen minutes, from the time when these colours were immersed in theoxv-muriatic acid, the logwood purple had nearly disappeared; and this was the case of the quercitron yellows in about three minutes afterwards, and of the shell purple about two minutes later; excepting that a part of the latter, as well as a part of one of the yellows given with tin, had each pre- served a portion of colour, by having been pro- tected, by other bits of muslin, from the sun's rays, which, as the sky was clear, had had free access to the phial containing them, at the window where this experiment was made ; a fact which manifested the influence of solar light, in promoting the. destructive action of the oxy-muriatic acid, on the colours in question. It is here to be recollected, that the three first- mentioned colours, dyed upon thealuminous basis, would have resisted the action of sun and air for two or threemonths, and the madder for a much longer time, and yet they were completely de- PERMANENT COLOURS. 73 stroyetl in an eighth part of the time which was required to destroy the logwood purple, and the yellows with tin; neither of which could have heen exposed to the sun and air for a single week, without becoming of a faded brown. It is also worthy of observation, that the Tyrian, or shell purple, was destroyed by the oxy-muriatic acid, almost as soon as the logwood purple and quercitron yellows last mentioned, though it would have resisted the sun and air, probably fifty times longer than either of them. The property by which certain matters decom- pose solar light, reflecting or transmitting some, and absorbing other rays, so as to produce the sensations or perceptions of particular colours, often depends upon precise, and nice proportions in the constituent parts of these colouring mat- ters, which proportions may be altered, and the colours resulting from them destroyed or changed by various means, acting even in opposite ways. Oxygene from its ubiquity, as a part of the atmosphere, and its powerful agencies, co-operates in almost all the changes which take place on, or above the surface of the earth, and especially in those connected with either", the production or the destruction of colours, and its presence as a constituent part of colouring matters, seems to be essentially neces- sary to those peculiar attractions, or affinities, 80 PHILOSOPHY OF* which, by their effects upon tlie rays of light, oc- casion the perceptions or sensations of colour. This will he abundantly proved, and elucidated by the highly instructing and interesting facts to be stated hereafter, concerning indigo. But though combinations of oxygene in certain proportions, are necessary to the existence of most, if not of all, colours, an excess of it may ob- struct all manifestation or appearance of colour, as completely as the total absence of it does, in regard to indigo. Of this a signal instance, and illustration, wilt be found hereafter, in the colourable matter of the Buccinum, produc- ing the ancient or shell purple; and this last, as I have already intimated, will moreover afford a most curious demonstration, and ex- emplification, of the influence of solar light, in one, and that the most common of the ways, in which it acts upon colouring matters; I mean that of separating or causing an abstrac- tion of their oxygene : and it will be readily perceived that these coloura ble matters (of indigo, and of the shell purple,) become the more interesting and instructive, by reason of their opposite conditions and analogies. To ascertain by well-directed experiments, made upon the several dying drugs, and the colours produced by them, with their usual or most suitable mordants, or bases, in which of the ways lately mentioned, or in what other PERMANENT COLOURS. 81 ways, their several colours are most liable to suffer injuries or decays, would doubtless contri- bute greatly to improve the art of dying, by enabling us to employ the means proper for ob- viating or correcting their respective defects, so as to render colours permanent, which have hitherto been deemed fugitive; and, perhaps, increase the durability and beauty, even of those which are considered as permanent. With this persuasion I have, at different times, projected various experiments, calculated to ascertain the effects of the sun's rays, upon co- louring matters, in all their usual combinations, when placed in vacuo, and also when immersed in the several kinds of air, and in alcohol, unc- tuous, and essential oils, diluted acids, and alka- lies, in order to ascertain the effects of these different agents or applications, upon the seve- ral colours ; and also as far as might be practi- cable, to discover what each had either lost or gained by such treatment. But from the num- ber and variety of my other unavoidable avo- cations, and interruptions, my progress in these experiments (excepting a few which will be mentioned in their proper places) has not been sufficient to warrant those ultimate conclusions, which could only be safely and properly drawn, after an examination and comparison of the whole ; and as I may not live or find leisure to execute the whole, I can only recommend the 82 PHILOSOPHY OF ^ subject to those who may have sufficient time and qualifications for a due investigation of it. Until further discoveries, therefore, shall have been made, I consider myself as only authorized to conclude, that the permanent colours of mat- ter do not depend upon the thicknesses, sizes, or densities of its parts or particles, but upon certain affinities or attractions, physical, or chy- mical, by which it is disposed and enabled to ab- sorb and conceal some of the rays of light, and to reflect or transmit other rays, producing the sensations or perceptions of particular colours ; and that to the existence or energy of these affinites, or attractions, certain portions of oxy- gene are generally necessary, as a constituent part of colouring matters ; and these portions may in some instances be increased, and in others dimi- nished, by the influence of radiant matter, or solar light, which may thereby contribute to the production of some, and the destruction of other colours. Should I be desired to assign a reason or cause for these affinities, and their connection with particular proportions of oxygene, I can only answer with M. de BufFort, that they who require the reason of a general effect, do not con- sider the infinite extent of nature's operations, nor the cpnfined limits of human understand- ing PERMANENT COLOURS. S3 CHAPTER II. Of the Composition and Structure of the Fibres of Wool, Silk, Cotton, and Limn. " Ubi natura desinit uobis incipiendum." Before I treat of the communication or pro- duction of colours by dying or calico printing, it will be proper to inquire concerning the par- ticular natures and differences of wool, silk, cotton, and linen, upon which these operations are usually performed. The two first are animal, and the latter are vegetable substances, differing from each other in their constituent parts and chymical properties, as well' as in structure and organization. M. Berthoilet has greatly contributed towards ascertaining their chymical differences, which seem principally to depend upon a much larger proportion of nitro- gene, and also of hydrogene, in the animal, than in the vegetable matters : and as the nitro- gene and hydrogene readily assume an elastic form, the wool, hair, and silk, in which they abound, have less adhesion between their con- stituent parts, than that which exists between those of cotton, and linen, and they are, there- fore, more strongly disposed, than the latter, to combine with other substances, when brought into contact with them ; and it is, I believe, partly in consequence of this disposition that g 2 8-1 PHILOSOPHY OF wool, hair, and silk, manifest stronger affinities or attractions for colouring matters generally, than cotton, and linen.* They are also more ready decomposed, or injured by acids, alkalies, and other chymical agents, which ought there- fore to be very sparingly used in the dying of animal substances : it being found that the sul- phuric, nitric, and muriatic acids readily decom- pose wool, hair, and silk, and at the same time destroy, or greatly weaken the texture and con- nexion of their several fibres ; and that alkalies prove equally injurious, by combining with them : though silk is indeed not so liable to be acted upon in these ways, because it partakes in some degree of the vegetable nature. Animal fibres, also, contain more oil and less of the basis of charcoal than the vegetable. It is from the superior chymical affinities, or attractions existing in wool, hair, aud silk, for * e. g. Cotton and linen will neither of them receive any- colour by the same preparation, and in the S3me liquor, which dyes wool or woollen cloth scarlet; This is every day seen by the cotton edges with which some sorts of cloth are wove, which remain white after the rest of the cloth is become scarlet. M. Dufay caused a piece of cloth to be manufactured, of which the chain was wool, and the woof cotton. This was afterwards fulled, that both might be brought into a similar state of preparation ; and the cloth being then dyed by the usual process, the woollen threads contained in it received a good scarlet, whilst the cotton remained white. PERMANENT COLOURS. 85 colouring matters, that the facilities with which these suhstances receive, and permanently re- tain colours, principally result; though some- thing is doubtless to be ascribed to the diffe- rences of conformation, existing between their fibres and those of cotton and linen, which I shall notice under their several heads. Article I. — Of Wool. The value of this substance, and its fitness for the different kinds of manufacture, depend in a great degree on the length and fineness of its fibres ; of which ample information may be found in a Memoir written by M. d'Aubcnton, and printed among those of the Royal Academy of Sciences, for the year 1775)* Wool is liable to great variations in quality, not only from differences in each particular race or breed of the sheep, from which it is taken, but also of the parts of the body to which it has adhered ; that which covers the tails, thighs, and bellies, being always coarser, and less susceptible of receiving colours by dying. It also frequently suffers in quality, and in colour, by the diseases to which sheep are liable ; the most healthy of the same flock, always affording wool which is of a better quality than that of the unhealthy ; and which has also a greater affinity for co- louring matters, and imbibes them more copi- ously by dying. S6 PHILOSOPHY OF "Wool is naturally covered by an unctuous substance, which probably is destined to secure it from the injurious effects of moisture. This substance (called yolk by the English, and suint by the French,) appears, by the experiments of M. Vauquelin, (Ann. de Chim. torn, xlvii. p. 27^.) to consist principally of a sort of animal soap, (having potash for its basis,) a greasy matter resembling suet, and a portion of lime in combination with the carbonic, acetic, and muriatic acids. To prepare wool for dying, this yolk is com- monly removed, by scovvering, or maceration for a quarter of an hour, in warm water, mixed with a fourth part of stale urine ; stirring the wool frequently by sticks, and afterwards rincing it thoroughly, if practicable, in running water. M. Vauquelin, however, thinks it may be advantageous, after wool has been cleansed from every thing which clean water can remove, to soak it for a i'tw hours, not in diluted stale urine, but in a tepid solution of soap, employing one pound of the latter, with a sufficient quan- tity of water, to every twenty pounds of wool to be scowered. M. Roard, director of the dying department of the French Imperial manufac- tories, thinks, that one pound of Flanders soap employed in this way, is sufficient for thirty pounds of wool; but instead of a tepid solution he recommends one that is heated ; though not PERMANENT COLOURS. 87 above 60° of Reaumur; equal to about 160° of Fahrenheit* He also recommends the spinning of wool in the yolk, and scowering it after- wards ; when he says, it will become much whiter than if scowered before the spinning. Another advantage results - from postponing this scowering, which is that of preserving the ■wool from the depredations of moths, and other insects, so long as it retains the yolk; an effect which Reaumur observed, and published in the year 1738. (See Mem. de L'Acad. Re. des Sciences for that year.) The wool of healthy sheep is always more copiously provided with yolk than that, of the sickly. When wool has been spun and wove, it commonly undergoes the operation of fulling, which I shall notice, because it depends upon such a. peculiarity in the structures of its fibres, as seems to increase its fitness to imbibe and retain colours by dying. Fulling, according to * M. Berthollet, in the last edition of his Elements, torn. i. p. 175, appears to think, that the substitution of soap for the ammonia contained in stale urine, has not been found advanta- geous in the trials made with it : M. Chaptal, however, in the ivth vol. of hishymie Appliquee aux Arts, p. 423, treating of this operation, says, that in Spain, and recently in France, cloths have been scowered without either stale urine, or soap, by preserving the water impregnated with the yolk, resulting from one operation, and employing it for a second ; and that of the second, for a third, &c. until it becomes so thick, and overcharged with yolk, as to be unlit for use. 8S PHILOSOPHY OF Sir William Petty (see Spratt's History of the Jloyal Society,) " is making- the cloth to become thicker, with the diminution of its other dimensions, and the covering of its threads, so as that the cloth shall seem to be translated from the likeness of a tela, (all of whose threads appear) to that of a hat, which has no threads at all ; for, by the way, the making of a hat (continues he) is the making of a tela, without spinning or weaving, by a kind of fulling." " This thickening," he adds, " is made by the shortening of threads ;" an effect which he erroneously ascribed to the heat of the mill, and the supposed astringent operation of urine, fullers' earth, &c. M. Monge has, however, lately given a bet- ter account of the operations of felting and full- ing, (see Ann. de Chymie, torn. vi. p. 300, &c.) by which it appears, that the " shortening of threads" is not produced by heat, or by any astringent power whatever, but an effect result- ing from the external conformation of the fibres of wool, fur, &c. which appear to be formed, either of small lamina placed over each other in a slanting direction, from the root towards the end or point of each fibre, like the scales of fish, lying one over the other, in succession, from the head to the tail ; or of zones, placed one upon another, as in the horns of animals ; from which structure each fibre, if drawn from PERMANENT COLOURS. 89 its root towards the point, will pass smoothly through the fingers; but if it be drawn in a contrary direction, from the point towards the root, a sensible resistance, and tremulous motion will be felt by the fingers. This conformation disposes the fibres of wool to catch hold of each other, and as they cannot recede, when acted upon by other bodies, they naturally advance, by a progressive motion, towards, and beside each other, from the end towards the root ; a disposition which is very inconvenient to spin- ning, and therefore the wool is greased, that the asperities arising from thi* structure of its fibres may be thereby covered, or sheathed, as a co- vering of oil sheathes those of a file. But the wool being manufactured, and the grease no longer useful, it is removed by scowering, not only for the sake of cleanliness, but that it may not frustrate the process of dying. The cloth is therefore carried to the fulling mill, and there subjected to the action of large beetles, with fullers' earth and water, by which the cloth is not only scowercd, but its fibres, in consequence of the structure just described, being made to conjoin, and advance toward, and beside each other, become shorter, and more closely con- nected, or felted together, the warp and woof losing in extent, but gaining proportionably in thickness. The lamina, or zones, under consideration, ya PHILOSOPHY OF afford many interstices in the fibres of wool, suited to receive and contain the particles of co- louring matters, when applied to them in the operation of dying; but these interstices being small, and the fibres of the wood naturally clastic, no colour can be conveyed into these cavities, until they are dilated by hot or boiling water; whereas silk, cotton, and linen, are made to receive colours without heat, as per- manently as with it. And this difference mani- festly arises from the smallness of the interstices in which the colouring particles are deposited in the fibres of wool, and their elasticity; and as the colouring particles are only made to enter and deposit themselves by an artificial dilatation, it follows that, when this ceases, the filaments will again contract to their former size, upon the colouring matters so introduced, and hold them much more strongly than they are likely to be held in other substances, whose interstices are large enough to receive colouring particles without being dilated, and which, therefore, cannot be supposed ever to contract and compress them in the same way: and this difference, joined to the superior chymical attraction of animal fibres for colouring matters, will sufficiently explain why many colours dyed upon wool prove so much more durable than upon cotton or linen. Wool, when dyed in the fleece, takes up much more co- louring matter than when spun, and much more PERMANENT COLOURS. 91 than when wove into cloth. It is also more or less penetrated, according to the fineness of its own texture, and the particular nature of the colouring matter with which it is dyed: the very finest cloth is never thoroughly dyed scar- let, it being always found white within when cut.* Wool taken from different breeds of sheep, in various countries, is naturally of different colours; as white, yellow, reddish, and black. Formerly, all the flocks in Spain, excepting those of Andalusia, were of this last colour, it havino- been preferred for wearing by the Spaniards ; and this natural (brownish) black is even at this time manufactured, and worn constantly by some religious orders in Roman Catholic coun- tries. The white wool, however, is now almost universally preferred to every other, as being sus- ceptibleof receiviugeven a better black by dying, than any which is natural. The cloth worn by Martial, appears to have received none but the natural colour of the wool, whatever that may have been. He says (xiv. 133) * The late Mr. Nash, and his successor, Mr. Dymock, in Gloucestershire, by causing broad cloths to be wove of threads but little twisted in the spinning, have succeeded in making their scarlet dye penetrate farther into the cloth than would otherwise have been practicable ; perhaps also this difference of, twisting may contribute to the remarkable beauty of their scar- lets, by an alternation in the affinity of light. .92 PHILOSOPHY OF " Non est lana mihi mendax, nee mutor aevo ♦ ■ — » me mea tinxit ovis. And Virgil, in predicting the auspicious events which were supposed by him to follow the birth of Marcellus, (nephew to Augustus) mentions the sheep as naturally producing wool, of the richest and most brilliant colours. " Nee varios discet mentiri lana colores : Ipse sed in pratis aries jam suave rubenti Murice, jam croceo mutabit vellera luto. Spoute sua sandyx, pascentes vestiet agnos." Eclogue iv. The lutum of the third of these lines appears to have been the Reseda luteola, or weld plant, now used as a yellow dye, and it has been con- jectured by professor Beckman, that the Sanctyx of the last line, which is represented as giving a red colour to the wool of the lambs feeding upon it, must have been the madder, which is known to have grown wild in many parts of Italy. Its leaves are said to impart a reddish colour to the milk of cows, when eaten by them, and the roots, notoriously stain the bones of hogs of a bright red, when they make part of the food of these animals. Article II. — Of Silk. it This consists of the fine threads composing the follicle of the Pupa, of the Bombyx Mori, PERMANENT COLOURS. i)3 a Math or Phalena belonging to Linneus's third order of insects. (Lcpidoptera.) It has been said and believed, that silk was exclusively produced in China, until the reign of the Greek Emperor Justinian. But of this there is no sufficient evidence. Pliny, indeed, after describing the countries inhabited by the Scy- thians, mentions the Seres as being the first or nearest civilized people beyond those regions; and he adds, that they were famous for the fine wool combed from their trees, of which he gives some account, so indistinct, however, that wc may doubt whether it does not relate to cotton, rather than to silk.* But there is a passage much less equivocal in his eleventh book, (Chap. 22,) where he mentions a kind of insects, greater than the wasps and hornets which he had just before described, and to which he gives the generic name of Bombyx, adding that they are produced in Assyria; and after a fabulous account of the nests and honey, which he supposed them to make like bees, he says, they engender in a dif- ferent manner ; i. e. from worms which put forth two horns; that these are Erucce, and afterwards * " Primi sunt hominum, qui noscantur, Seres, lanicio sylva- rum nobiies, perfusam aqua depectentes frondium canitiem : unde geminus foeminis nost lis labor, redordiendi fila, rursumque texendi. Tam multiplici opere, tam longinquo orbe petitur., ut in publico matrona transluceat." Lib. vi. cap. 1/. bibe, but in making them retain, the colouring particles when imbibed ; because, being admit- ted so readily, into their undilated pores, they cannot be afterwards compressed, and held therein, by any contraction of these pores, as is done in those of wool. We know that it re- quires twice as much cochineal, to produce a crimson on silk, as on wool ; which is a proof that it can take up a greater quantity, and con- sequently that its pores are at least sufficiently large, and accessible: we know also, that un- bleached cotton is always preferred for dying the Turkey red, it being found to retain the colour most permanently ; doubtless, because its pores, or interstices are less open before, than after the operation of bleaching. This is also the case of raw or unscoured silk, which, as the ingenious Mr. Henry of Manchester, observes, is " more easily and permanently dyed, than that which has passed the above described process," of whitening and scouring : and, indeed, the openness of the pores of cotton and linen, and their consequent readiness to imbibe, both co- louring particles, and the earthy or metallic bases employed to fix most of them, are circum- stances upon which the art of calico printing is in a great degree founded. To prepare and dispose cotton for receiving colours by dying ; it is commonly boiled, in a very diluted solution of vegetable or fossil alkali, for about two hours. 110 PHILOSOPHY OF and afterwards rinced in clean running water ; and for calico printing, it is soaked in water, acidulated with about one-fiftieth of its weight of sulphuric acid, and afterwards rinced tho- roughly in a clear stream of water. Cotton bears the action of acids much better than either wool or J in en. Concerning flax, and its conversion to linen, so much has been written, both by ancient and modern authors, and its preparation for dying, so nearly resembles that of cotton, that I may hope to be excused, for not discussing this sub- ject. PERMANENT COLOURS. ill CHAPTER. III. Of the different Kinds and Properties of colouring Matter, employed in Dying, Calico Print- ing, $c. " Toutes les choses visibles se tlistinguent ou se rendent " desirable par la coulcur." Colbert. Instruction general pour la Teinture,S$c. By colouring matter, I understand a substance which possesses, or acquires a power of acting upon the rays of light, so as either to absorb them all, and produce the sensation of black ; or only to absorb particular rays, and transmit or reflect others, and thereby produce the per- ception of that particular colour, which belongs to the ray or rays so transmitted or reflected. Among minerals, the colouring matter of each is commonly distributed equally to all its parts ; but in animal and vegetable substances, it generally exists in particular parts, or par- ticles, which are capable of being extracted and collected for the purposes of dying, &c. Colouring matters possess peculiar chemical properties, which distinguish them from all other kinds of matter; for besides their several affinities with particular rays of light, they have others which render them susceptible of being- acted upon, and modified by a variety of che- mical agents, as well as of forming permanent 112 PHILOSOPHY OF combinations with the filaments of wool, silk, cotton, linen, &c. Bu^ in respect of these affi- nities, colouring matters also differ essentially from each other, and must therefore be applied in different ways, and with very different means, to produce permanent colours in other matters. The art of dying is founded upon a knowledge of the particular properties and affinities of these matters, not only as far as they relate to the substances intended to be dyed, but also as far as they are connected with the operations of other agents, by which they are liable to be acted upon, either during the process of dying, or afterwards. Many species of animal and vegetable co- louring matters, suffer nearly similar changes from the action of acids, alkalies, and other chemical agents ; from which it may be pre- sumed, that there is something of a common, or similar nature, in the constitution of many of them. But though it would be highly useful to establish general principles and conclusions on this subject, we are not yet furnished with the necessary facts ; and whilst this continues to be the case, it will be best to wait, or rather seek, for more knowledge, and avoid fallacious suppositions or explanations. Sir Isaac Newton supposed coloured matters to reflect the rays of light; some b /dies re- flecting the more, others the less refrangible PERMANENT COLOURS. 113 rays most copiously ; and this he conceived to be the true, and the only reason of their colours. Mr. Delaval, however, has lately maintained (in the 2d. vol. of the Memoirs of the Philosophical and Literary Society of Manchester,) " that, in transparent coloured substances, the colouring matter does not reflect any light ; and that when, by intercepting the light which was transmitted, it is hindered from passing through substances, they do not vary from their former colour to any other colour, but become entirely black :" and he instances a considerable number of coloured liquors, none of them endued with reflective powers, which, when seen by transmuted light, appeared severally in their true colours ; but all of them, when seen by incident light, appeared black : which is also the case of black cherries, black currants, black- berries, &c. the juices of which appear red when spread on a white ground, or otherwise viewed by transmitted, instead of incident light ; and he concludes, that bleached linen, cotton, &c. " when dyed or painted with vegetable colours, do not differ in their manner of acting on the rays of light, from natural vegetable bodies ; both yielding their colours by trans- mitting through the transparent coloured matter, the light which is reflected from the white ground :•" it being apparent, from dif- ferent experiments, u that no reflective power : 114 PHILOSOPHY OF resides in any of their component parts, except in their white matter ouly," and that " transparent coloured substances, placed in situations by which the transmission of light through them is inter- cepted, exhibit no colour, but become entirely black." " The art of dying, therefore (according to Mr. Delaval,) consists principally in covering white substances, from which light is strongly reflected, with transparent coloured media, which, according to their several colours, trans- mit more or less copiously the several rays re- flected from the white substances," since " the transparent media themselves reflect no light ; and it is evident that if they yielded their colours by reflecting, instead of transmitting the rays, the whiteness, or colour of the ground on which they are applied, would not in any wise alter or affect the colours which they exhibit." Having had reason to differ from Mr. De* laval on other points, I am happy in being able to agree with him on this, so far as relates t6 transparent colouring matters, when applied to wool, silk, &c. without the interposition of any earthy or metallic basis. But when any such opake basis is interposed, the reflection is, doubtless, made principally by it, rather than by the substance of the dyed wool, silk, &c. and more especially when such basis consists of PERMANENT COLOURS. 115 the white earth of alum, or the white oxide of tin; which, by their strong reflective powers, greatly augment the lustre of colours. There are, moreover, some opake colouring matters, particularly the acetous, and other solutions of iron, used to stain linen, cotton, &c. which must necessarily themselves reflect, instead of transmitting the light by which their colours are made perceptible. It has been already mentioned, that when the rays of light are separated from each other by the prism, in consequence of their different degrees of refrangibility, they produce a per- ception of seven distinct colours, with all their intermediate shades ; and that these are all equally simple and primitive. There is, how- ever, this peculiar property belonging to the red, yellow, and blue colours, whether pris- matic or permanent, that they are incapable of being produced, like all the rest, by the combi- nation of any other colours. Blue and red will compose a purple ; blue and yellow, a green ; red and yellow, an orange, &c. ; but none of these, by any composition, will produce either the blue, yellow, or red : these last, therefore, are in all cases simple or uncompounded ;* but * Dufay would only admit of three primitive colours, red, blue, and yellow, because with these dyer3 and painters can readily p compound all the others > and a late writer, adopting Dufay's I 2 116 PHILOSOPHY OF all the others may be, and in reality are, some- times simple, and sometimes compounded ; and this is true not only of those which are merely prismatic colours, but of those which exist naturally in bodies, or are communicated by painting, dying, &c. Iron, as has been already mentioned, will, by different degrees of oxyda- tion, produce all possible varieties of colour ; and these colours will be all simple or uncom- pounded ; and so will the purple of gold, the green of copper, and the other colours found in the several oxides of metals. This is also the case of the violet and purple dyed from log- wood ; of the green of the leaves, &c. of vege- tables ; and of the orange dyed from the quer- citron bark, as will be hereafter mentioned. And among animal colours, numerous instances may be alleged of simple or uncompounded greens, oranges, purples, and violets : even the yellowish white liquor of the murex, and buc- cinum, from which the celebrated Tyrian purple was produced, passes quickly through all the shades of yellow, green, violet, and purple, upon being exposed to the sun ; and these must necessarily be deemed simple, not compound colours. But on the other hand, dyers, painters, opinion on this subject, says, the colours of the prism arc im- material, accidental, and artificial. But those of the dyer and painter are substantial, natural, and palpable. PERMANENT COLOURS. 117' &c. daily produce orange, green, purple, and violet, by mixtures of the blue, yellow, and red : nor is it necessary that these should be intimately mixed, since cloth woven from a red warp, and a blue woof, will appear to be uniformly purple or violet ; or if the warp be yellow instead of red, the cloth will appear green, in each case exactly resembling the simple homo- geneous colour, which, in the prismatic series, lies between the colours of the warp and woof. It has moreover been repeatedly found in dying compound colours, as for instance, green, that laying a permanent blue over a fugitive yellow, does not defend the latter, or make it in any degree more lasting, but that it will decay (leaving the blue in full strength) as rapidly as if no blue had been applied ; and therefore we may presume, that the fibres of the dyed stuff were but partly covered with the yellow co- louring matter, and that when the blue came to be afterwards added, its particles found spaces sufficient to lodge themselves collaterally, without being placed upon the yellow particles. Several attempts have been made to arrange and class the different species of colouring mat- ters employed for dying and calico printing ; but none seems to accord with, or give just ideas of, their several natures and properties. M. Berthollet, indeed, alleges sufficient reasons • for not dividing these matters, as Mr. Macquer 118 PHILOSOPHY OF did, into extractive and resinous, and also for not making their effects depend, as Mr. Poerner has done, upon the mucilaginous, earthy, saline, resinous, or oily parts of which they were sup- posed to he compounded, but without proposing any suitable arrangement of his own. To me, however, colouring matters seem to fall naturally under two general classes ; the first including those matters which, when put into a state of solution, may be fixed with all the permanency of which they are susceptible, and made fully to exhibit their colours in or upon the dyed substance, without the interpo^ sition of any earthy or metallic basis; and the second, comprehending all those matters which are incapable of being so fixed, and made to display their proper colours, without the media- tion of some such basis. The colours of the first class I shall denominate substantive ; using the term in the same sense in which it was employed by the great Lord Verulam, as denoting a thing solid by, ov depending only upon, itself; and colours of the second class I shall call adjective, as implying that their lustre and permanency are acquired by their being adjected upon a suitable basis. Earthy and metallic bases when thus inter- posed, serve not only as a bond of union, between the colouring matter, and the dyed substance, but they also modify (as well as fix) PERMANENT COLOURS. 119 the colour; some of them, particularly the oxide of tin, and the earth of alum, exalting and giving lustre to most of the colouring mat- ters, with which they are united ; whilst others, and especially the oxide of iron, blacken some, and darken almost all such matters, if made to combine with them. Substantive colouring matters are but few in number, because a few only of the substances employed in dying, possess such decidedly energetic affinities, as to be able to contract a permanent union with the stuffs to be dyed, merely by being applied to, or brought into contact with them. This is more especially true of linen and cotton ; for in regard to wool, several of the adjective colouring matters, par- ticularly those of Madder, Cochineal, Kermes, and Lac, are so much attracted by it, that with the aid of boiling water they fix themselves in, or to, the fibres of wool, so as to produce co- lours of some, though less durability, than those which would have been produced if a basis of alumine, or the oxide of tin, had been also applied, and without such basis, these colours never rise so high, or acquire so much lustre as they would have done therewith. Of substantive colours, I shall first notice the animal, next the vegetable, and, lastly, the mineral. 120 PHILOSOPHY OF CHAPTER IV. Of substantive Animal Colours, and principally of the Tyrian Purple. ■■ " Tyrioquo ardebat murice lana* Virg. y£ncid, lib. iv. " Raic fasces secures que Romance riam faclunt : idemque pro majtstate pnemiae est : distinguit ab equite Curiam : Diis advocatur placandis : om» lnqne vestem illuminat ; in triumphaU miscetur auro : qua prop- ter e^cusata et purpura sit insania." CaiiPlmii seenndi Hist. Lib. ix. cap. 36. This, during many ages, was the most celebra- ted, and venerated of all the colours given by dying ; and among the rich and beautiful, it seems to have been the first which mankind were enabled to fix permanently on wool, and linen. It was obtained from a whitish half-fluid matter, secreted by particular organs in certain univalvular shell fish, and retained in an appro- priated receptacle, with which they were each naturally provided : though we are completely ignorant 'of any benefit which this secretion produced to the fish themselves. There is much obscurity, and some incon- sistency in the accounts transmitted by ancient writers of the shell fish, which afforded the purple dye. Those of Pliny are the most copious and intelligible, though thev are sometimes at variance with each other. He mentions these fish under the several names of Conchylium, Murex, Purpura, and Buccinum ; and these se- PERMANENT COLOURS. 121 veral names have been also employed by other Latin authors. But Fabius Columna, a noble Neapolitan, who first published figures of plants, from engravings made by his own hand, and wrote a learned dissertation de purpura, (printed at Rome in \6\6) after much pains employed, to elucidate and reconcile the diffe- rent passages of ancient writers on this subject, thinks himself warranted to conclude that there were but two kinds or genera of these fish, viz. the purpura and the buccinum : that the term conchylium, signified generally all the species of purpura?, and that it was also used sometimes to signify the purple colour itself; that Pliny em- ployed it in the former sense, in the 41st chap- ter of his 9th book; and in the latter, in the 36th chapter of the same book, that the term murex, was also used as a generic name for the purpuric; and consequently that both conchy- lium, and murex, were synonymous, of the pur- pura ; " quarum alterum a conchis nomen, alterum abaculeis, qui alio nomine muriccs dicuntuiv' I am afraid, however, that Pliny was neither constant nor correct in using these names, even in the ways by which Columna endeavours to render him consistent and intelligible, for in the chap- ter last quoted, he mentions the purpura, and the murices, as being different fish, and compares their respective habits, &c. adding as a peculia- rity of the former, " Sed purpuras florem ilium 322 PHILOSOPHY OF tingendis expetitum vestibus, in mediis habent faucibus : liquorls hie minimi est in Candida vena, unde pretiosus hie bibiturnigricantis rosas colore sublucens." It seems probable that the term murex,* was in this instance erroneously substituted for buccinum ; as he proceeds to state that all the shell fish yielding the purple, or other lighter colours of the conchylia, are in matter the same, and differing only in tempe- rament ; that they are of two kinds, (" duo sunt genera'') one which is the lesser kind, being called buccinum, from its likeness to the horn or cornet, so named and employed to pro- duce sound by blowing through it (" quo sonus editur.") These last he describes as being round at the aperture, with a serrated margin. Theother kind, says he, is called purpura, and has a pro- jecting pipe-shaped beak (rostrum) with a lateral winding cavity, through which it puts forth its tongue ; the body of the shell is moreover muri- cated, or armed, even to its upper pointed extre- mity, with rows of spines, seven in number ; which are wanting in the buccinum. This last, he adds, adheres to rocks and large stones, whence it can alone be collected. * " Murex cochlea est maris, dicta ab acumine et asperitate quae alio nomine conchylium nominator, propter quod circum- cisa ferro, lacrymas coloris purpurei emittat, ex quibus purpura tingitur, inde ostrum appellatum," &c. Isidorus, lib. 2. Ori- gin, cap. 6. PERMANENT COLOURS. 123 In the same chapter, Pliny tells us, that the best purpuras found in Asia, were those taken in the sea adjoining to Tyre : that in Africa the most esteemed were those of Meninx (Me- ninge), and the sea coast of Getulia : and in Europe those of Laconica. He adds that the Tyrians, when they caught any of the greater purpura;, took the fish out of their shells, the better to extract the colouring matter, but that they obtained it from the smaller, by grinding them in mills. That the fishermen endeavoured to take the purple fish alive, because it otherwise ejected and lost its precious liquor, together with its life. But on this point he seems to have been misinformed, there being good reason to believe that this fish never ejects the liquor in question.* He adds, moreover, that this fish dies speedily, if put into fresh water, but that it will otherwise live upon its own saliva, 50 days after being taken. In the next chapter, Pliny tells us, that the purpuras Avere also called pdagicc, (probably * This is, at least, true of buccinum, whose colouring mat- ter I found unaltered some days after the fish, or limax had died slowly, by being kept seven or eight weeks without water, and it was not until putrefaction had made a sensible progress, that the colouring matter became incapable of producing its proper effect. 124 PHILOSOPHY OF from their inhabiting- the ocean) and that there were several varieties of them, named differently from the places were they were found, and the food on which they subsisted; and he after- wards describes the manner in which they were caught. In his 38th chapter, he states, that when the purpura: were caught, the white vein or receptacle, before described, was taken out and kid in salt for three days, after which a sufficient quantity of the matter so extracted and salted, was boiled slowly in leaden vessels, over a gentle fire, the workmen from time to time skimming off the fleshy impurities : this process lasted ten days, after which the liquor was tried by dipping wool into it, and if the colour produced by it was defective, the boiling was renewed. Pliny afterwards erroneously represents the liquor of the buccinum as only yielding a fugitive colour ; and says it was com- monly mixed with more than half as much of the liquor of the pelagium, which of itself gave a very dark purple ; and that being so mixed these liquors improved each other, the latter giving permanency to the former, and being in return brightened and enlivened by it ; and thus producing a most beautiful amethyst co- lour. (" Amethysti color eximius illc.") He adds, that the Tyrians produced their purple, by first dying the wool with the unprepared or PERMANENT COLOURS. I2i greenish liquor of the pelagimn, and afterwards in the liquor of the buccinum, and that this co- lour was deemed most perfect, when it resem- bled the colour of coagulated blood, &c. "Laus ei summa color sanguinis concreti, nigricans as- pectic, idem que smpectu refulgens : unde & ho- merus purpureus dicitur sanguis." In his forty-first chapter, Pliny farther tells us, that it not being thought sufficient to transfer the colour of the amethvst to wool, it had become the practice to dye the latter again, with the Tyrian purple, that it might obtain a compound name (Tyriamethystus,) corresponding with this double luxury : and that beinp- satu- rated with colour of the conchylium, it was deemed fitter to receive the Tyrian dye. He adds, that not content with thus combining colours obtained from the ocean, recourse was also had to those produced on the land ; and that wool, or cloth, dyed crimson, from the coccus (kermes,) was afterwards made to imbibe the Tyrian purple, in order that it might assume the colour which was named hysginus, after a flower so called : this colour partook greatly of the crimson tint. But besides the coccus (kermes,) other colouring matters were em- ployed, sometimes to ceconomize, and at others to vary the effects of the liquors of the purpura and buccinum ; and more especially that of the lichen roccella, or archil, which Pliny mentions * 126 PHILOSOPHY OF under the name of fucus marinus, and which, even at this time, is greatly employed in dying, though its beautiful purple colour fades rapidiy. Indeed, this lichen, or moss, was in such general use as a dye, at and before the time when Pliny- wrote, that its name fucus came at length to signify generally, colours given by dying; of this, among numerous other instances, may be quoted the following line, by Catullus (de Nuptiis Pelei and Tetidos,) viz. '* Tincta tegit roseo conchylis purpura fuco." of this fucus, that from Crete was the most esteemed. Pliny tells us also, Lib. xxii. cap. 17, that the alkanet root, (anchusa tinctoria) was like- wise employed as a ground for the purple dye. By these and other means, the purple colour was made to assume a variety of shades, some inclining more to the blue, and others more to the crimson. The principal of these varieties were noticed by Pliny, in the eighth chapter of his twenty- first book, when, after mentioning the luxurious art by which men had surpassed the savour of natural flowers, by artificial odours, he adds, that they had also learned by dying, to emulate the finest colours of these flowers ; and that of these beautiful dyes there were three divisions ; one in Avhich the coccus (kermes,) was employed, and which equalled the brightest colour of the rose, (" qui PERMANENT COLOURS. 127 in rosis micat;") and here he observes, that nothing could be more grateful to the sight, than the Tyrian and Laconican purples, especially when twice dyed (dibaphasquc." # ) In the se- cond division he mentions the amethyst, inclining to the violet ; and also the purple called jan- thinus.j* His third division includes the colour strictly called conchylium, of various tints ;J one resembling the heliotrope or turnsole, of which says he, there are several shades ; another ap- proaching the mallow, with a mixture of purple, and a third, resembling the later violet, (" viola * Horace alludes to this twice dyed purple, (pupura di capha) in the following lines. " Te lis afro murice tinctae vestiunt lanae" — and " Muricibus tyriis iterates vellera lanae." f The amethyst purple was lighter, and partook more of the blue tint than the dark Tyrian dibapha : that variety of it called janthinus was so named from ja, a species of violet. % Lucretius de rer. nat. 1. vi. says of this colour : " Purpureusque color conchyli jungitur una, Corpore cum lana." It was lighter and had less body than the Tyrian purple, being dyed with half the quantity of the liquor of the purpura; it also inclined more to the blue, whence it frequently acquired the names of hyacinthus, and caeruleus j and, from its having less body, those of color dilutus, and ablutus ; which last word by abbreviation is supposed to have produced that of hlutus ; whence the French lieu, the English, Hue, and the German blau. Braun says this colour is called thechelet in th» Hebrew Bible, and the shell fish producing it chilzon. Brauu de vests. Saceid. Hebraeor. i. 12. 123 PHILOLOPHY OF serotina," probably, the purple stock gilly- flower :) this he mentions, as being the richest colour that could be obtained from the purple shell fish : and thus, says he, nature and art striving against each other, maintain an equal conflict. " Paria nunc componuntur, et na- tura atque luxuria depugnant." Various (and probably fabulous) accounts of the first discovery of this purple, have been related by different writers. One of these •ascribes it to a dog, who, when following the nymph Tyros, and a certain Hercules her lover, along the sea shore, caught one of the purpura; lying on the sand, and breaking the shell with his teeth, his mouth became coloured with the purple juice, which the nymph observing, expressed a strong desire to obtain a dress dyed of this colour. And the lover anxious to satisfy her desire, discovered by a proper examination, how tliis beautiful purple might be obtained, and communicated by dying.* And the nymph, by whom the purple so discovered was first worn, being named Tyros, the colour is supposed to have thence obtained the appellation of Tyrian purple. Others have related, that this discovery was made by the Phoenician Hercules,f and * See Cassiodorus, lib. i. and Julii^s Pollux, lib. i. 4. from the latter, Polydore Virgil has taken the story. f Sir Christopher Hawkins, in his " Observations on the tin trade in Cornwall/' (lately published) mentions this Her- PERMANENT COLOURS. 129 afterwards communicated it to the king of Phoenicia, who thereupon, immediately began tc wear purple. (See Goguet, 1. ii. ch. 2.) That this colour first became known at the city of Tyre, and thence obtained its name, is rendered probable by the fact, of its having also borne the cules, as one said to have been the greatest Phoenician navigator, " and the first who brought tin from the Cassiterides, or British isles :" and, adverting to the story of his having also " invented the shell purple, by accidentally remarking that a dog's mouth was stained therewith," he observes, that " as both these discoveries are attributed to the same person, we may thence infer, that the tin of Britain was an essc7ilial ingredient in fixing the fine purple dyes of the ancients ; or, (adds Sir Christopher,) as Mr. Polwhele elegantly expresses it, " very possibly the purple dye of the Tytians, gained its high reputa- tion among the ancients, from the use of our tin, in the com- position of the dye stuff, as the tin trade was solely in their own management." On this subject, however, Sir Christopher, perhaps, from a partiality in him, both natural and excusable towards Cornwall, has departed from his usual logical accuracy, and hazarded ah inference which his premises do not warrant ; for though it were true, that tin was first earned to Tyre, and the shell purple first discovered there, by the same person; we should have no right to conclude that the former was necessarily employed to produce the latter j and there is not only no evidence that this ever tvas, but on the contrary, many facts prove that it never could have been the case ; indeed, my own experiments will show, that the colourable matter of the buc- cinum attains its beautiful purple, and fixes itself permanently, without any other aid than that of solar light, and also that solutions of tin are completely useless for either of these pur- poses : nor is there the smallest reason to suspect that they ever were employed for dying, until the seventeenth century. 130 PHILOSOPHY OF appellation of Sarramts, from Sarra, the name by which that city had been previously distin- guished ; and, hence the following line of Vir- gil, (2 Georg. 506.) " Ut gemma bibat, et Sarrano dormiat Ostro." Respecting the time when this discovery was first made, the more ancient writers do not agree, some stating it to have been about 1500 years previous to the Christian aera, and others almost a century later, whilst Minos reigned in Crete. Plhi}' appears to think, that purple had been w r orn at Rome, soon after the building of that city, but that even Romulus never wore it, except in his trabea, or regal mantle: and he In another paragraph, which Sir Christopher has subse- quently quoted, from Mr. Polwhele, the latter supposes, that the Phoenicians must have known the use of tin, " as one of the non-colouring retentive ingredients j" because, " it is not likely that the simple blood of the shell Jish, however beautiful at first, could have proved a lasting dye " and, therefore, he imagines, that " some retentive ingredient," (like " tin dis- solved in aqua fords,") must have been necessary to secure its brightness, and preserve its beauty." — The " brightness and beauty of the " simple blood of a shell fish ! .'" — Of the " purpura," and the buccinum ! ! ! As well might Mr. Polewhele expatiate on the brightness and beauty of the simple blood of the oyster and the snail j and sup- pose that by the help of tin, they would produce the Tyrian purple. How an idea so extravagant, and so indicative of gross inattention to the common productions of nature, could have occurred to this gentleman I know not, unless he derived it from the following lines of Martial, viz. " Sanguine de nostro tinctas, Ingrate, lacernas Induis ; et non est hoc satis ; esca. sumus." PERMANENT COLOURS. 131 states, as a certain fact, that Tullus Hostilius was the first king of Rome, who assumed the pretext a or long robe, with broad purple stripes., after having subdued the Tuscans. He adds, " Nepos Cornelius, who died in the reign of Augustus Cassar, when I was a young man, assured me that the light violet purple, had been formerly in great request, and that a pound of it, was commonly sold for 100 denaria, (nearly ^4 sterling :) that soon after the tarentine or reddish purple came into fashion ; and that this was followed by the Tyrian di- bapha, which could not be bought for less than 1000 denaria, (almost ^40 sterling) the pound; which was its price when P. Lentulus Spinter was iEdile, Cicero being then Consul* But after this, the double-dyed purple became less rare, &c." See lib. ix. c. 39. As soon as mankind were acquainted with the purple as a dye, they seem to have consi- dered it, not only as being of all others the most estimable in itself, but also the most acceptable to the Gods. It was, therefore, naturally appropriated to the services of religion, and of its ministers, as well as to distinguish the highest civil and military dignities. Pliny has noticed the use made of it by Romulus, and succeeding Kings of Rome, as well as after- wards by the consuls, and higher magistrates of the republic. Under the Roman Emperors, it k 2 U2 PHILOSOPHY OF became the peculiar emblem, or symbol of majesty, and the wearing of it by any who were not of the Imperial family, was deemed a treasonable usurpation, punishable by death ; as was mentioned by Suetonius. (Vita Neronis.) Hence the expressions of " sacer murex," and of 11 adorare purpuram? in the Roman laws. (See BischofT Versuche, &c.) When so much importance and sanctity (if I may use this expression,) had been attached to this colour, the dying of it was confined to a few particular places, and also to a few persons called muricileguli ; and we need not therefore wonder, that after the Greek empire had been overthrown, the knowledge of the shell fish affording the purple colour, as well as the ways of employing them as a dye, should have been completely lost in the 12th century ; and that afterwards, when learning began to revive, some persons should have doubted, whether either of these had ever existed ; nor need we wonder, after this loss, that the high pre-eminence which had belonged to the purple, was in a considerably degree transferred to the scarlet, afforded by the kermes ; which after being called red purple, at length obtained the name (un- known to the ancients) of scarlet* as we * This colour afterwards obtained the name of Venetian scarlet, to distinguish it from the brighter colour, now called PERMANENT COLOURS. 133 learn among others from Caneparius ; who, in his work dt Atrament is, p. 207, after mentioning that the ancient purple then unknoxvn, had formerly dis- tinguished Emperors, Kings, &c. adds, " Nostra autetn aetatc (the beginning of the 17th cen- tury) hujuscemodi vestes vocantur scarlati, quibus Venctiis illustrissimi, Scnatores procedere conspicinntur." — Again, in the next page he says, " Quamobrem ubique, et Venetiis pra> seriim maxime existimatur purpura, vulgari dictione, dicta escarlatam y pro illustrissimis pa^ triciis insigniendis." He mentions also that the violet purple was then commonly called " el Pavonazzo" by the Italians. It was probably then dyed from archil only, It happened, however, more than sixty years after the work of Canniparius had been printed at Venice, that Mr. William Cole, of Bristol, being at Minehead (viz. in 1683,) he was there told, of a person living at a sea-port in Ireland, " who made considerable gain by marking, with a delicate durable crimson colour, the fine linen of ladies and gentlemen, sent to him for that pur- pose;" and that this colour was "made by some liquid substance, taken out of a shell-fish." Mr. Cole being a lover of natural history, and hav- scarlet and which had never been seen until Cochineal, and the effect of solutions of tin upon its colouring matter, were diicoveied, about the year 1630. 134 PHILOSOPHY OF ing his curiosity thus excited, went in quest of these shell-fish ; and after faying various kinds without success, he at length found considerable quantities of a species of buccinum on the sea- coasts of Somersetshire, and the opposite coasts of South Wales ; and after many ineffectual endeavours, he discovered the colouring matter placed in a " white vein, lying transversely in a little furrow, or cleft, next to the head of the fish ;" which, says he, " must be digged out with the stiff point of a horse-hair pencil, made short and tapering, by reason of the viscous clammi- ness of the white liquor in the vein, that so by its stiffness it may drive in the matter into the fine linen, or white silk," intended to be marked. Letters or marks made in this way, with the w r hite liquor in question, " will presently," adds he, " appear of a pleasant green colour, and if placed in the sun, will change into the following colours, i. e. if in the winter, about noon, if in the summer, an hour or two after sun-rise, and so much before setting (for in the heat of the day in summer the colours will come on so fast, that the succession of each colour will scarce be distinguishable ;) next to the first light green, will appear a deep green ;" " and in a few minutes this will change into a full sea green ; after which, in a few minutes more, it will alter into a watchet blue; from that, in a little time more, it will be of a purplish red ; after PERMANENT COLOURS. 135 which, lying an hour or two (supposing the sun still shining,) it will be of a very deep purple red ; beyond which the sun can do no more.'' He remarks, however, " that these changes are made faster or slow r er,, according to the degree of the sun's heat;" "but then," adds he, " the last and most beautiful colour, after washing in scalding water and soap, will (the matter being again put out into the sun or wind to dry) be much a differing colour from all those mention- ed, i. e. a fair bright crimson, or near to the Prince's colour ; which afterwards, notwithstand- ing there is no styptic to bind the colour, will continue the same, if well ordered, as I have found in handkerchiefs that have been washed more than forty times ; only it will be somewhat allayed from what it was, after the first washing." Mr. Cole found, that, if linens marked with the white liquor in question were taken out of the sun, w^hen the colours had only reached any one of the before-mentioned shades, and shut up between the leaves of a book, the colour or colours made no farther progress whilst so shut up, but remained always of the same shade. He also found, that whilst linen marked with the w r hite liquor was drying by exposure to the sun, for the Jirst time, it would always " yield a very strong foetid smell (which divers who smelt it could not endure,) as if garlick and assafoetida were mixed together ;" and this hap- 136 PHILOSOPHY OF pens in cases where linen, after being marked, had been shut up in a book for twelve months, before it was exposed to the sun's rays. He also found, that the colour in linen which had been dried, and washed immediately after being mark- ed, was better than when it had lain fourteen •months between the leaves of a book, unwashed. Mr. Cole sent some of the first linen marked by him in this way, to Dr. Plot, then one of the Secretaries of the Royal Society, in November, 1684; and it was soon after shewn to King Charles the Second, who admired it greatly, and desired that some of the shell-fish mi^ht be col- lected and brought to town, that he might see the liquor applied, and the successive changes of colour which it underwent ; but before this could be done, the king died ; and though Mr. Cole's letter (from which the preceding extracts were made) was in the following year published, in the fifteenth volume of the Philosophical Transactions, and excited the attention of philo- sophers in most of the countries of Europe, it does not appear that any attempt was made to revive the practice, along* with the knowledge, of dying the ancient purple. After an interval of twenty-four years, M. Jussicu found a smali species of buccinum, in form resembling the garden snail, on that part of the French coasts which is washed by the Atlantic ocean, and presented some of them, in PERMANENT COLOURS. m the year 1709, to the Royal Academy of Sci- ences at Paris; and in the following year, the celebrated M. Reaumur found great quantities ofrhe buccinum on the coast of Poitou ; and he moreover observed, that the stones, and little sandy ridges round which these shell-fish had collected, were covered with a kind of oval •" graines," some of which were white, and others of a yellowish colour ; and having epU lected and squeezed some of these upon the sleeve of his shirt, so as to wet it with the fluid or liquor which they contained, he was agreeably surprized, in about half an hour, upon finding it stained of a fine purple colour, which he was unable to discharge by washing. This was done upon the sea-shore. He next collected a quan- tity of these grains, and carrying them to his apartment, bruised and squeezed different parcels of them upon bits of linen ; but to his great sur- prize, after waiting two or three hours, no colour appeared upon the spots wetted with their liquor. Unable to conceive the reason of this disappoint- ment, and having almost determined to return again to the sea-shore, and repeat his experiment in the same place as before, he chanced to per- ceive some purple spots, occasioned by drops of the liquor which had accidentally fallen upon a part of the plaster of Paris with which the sides of the window were covered, and which, having been more strongly acted upon by the light, 138 PHILOSOPHY OF than the bits of linen wetted with the same li- quor in the interior part of the room, had become purple, though the day was then cloudy. With- out, however, perceiving this to have been the cause of his disappointment, he broke off a bit of the same plaster, and carrying it to the back part of the room, where the bits of linen in ques- tion were laying, he wetted it with the same liquor, without its becoming coloured. He then thought of carrying the colourless bits of linen to the window, which was open, and there he soon perceived them to become purple. It was then fashionable to explain all effects upon me- chanical principles, as it had been at the time when he also endeavoured to account for the shock of the torpedo, as resulting mechanically from a very quick stroke given by the contraction of parti- cular muscles in that iish. M. Reaumur, there- fore, soon persuaded himself, and others, that the bits of linen which had remained colourless whilst at the back part of his room, were rendered pur- ple at. the window by the different manner in which the air acted upon the colouring liquor in the latter; and that this difference consisted solely in the air's having greater motion at the window, than at a distance from it ; and almost all his subsequent experiments, seem to have been calculated to confirm this erroneous hypo- thesis. He placed bits of linen, just wetted with the PERMANENT COLOURS. 139 colouring liquor, in the open air, and laying a stone upon each, he found the covered part re- main colourless, whilst the rest were made pur- ple ; which he ascribed to the mechanical im- pression of wind, not considering that the stones kept off the light, as well as the air. — Having read an account of Mr. Cole's observa- tions, in the Philosophical Transactions, M. Reaumur exposed a bit of linen, wetted with the colouring liquor, to the rays of the sun, col- lected by a small burning glass, and saw it be- come purple in an instant; and consequently, without being able to distinguish any of the changes of colour through which it had so ra- pidly passed. Putting another bit of linen, wet- ted with the same liquor, so near to the fire that it would have burned had it been dry, he like- wise saw it become purple immediately; but with equal degrees of heat, the effects produced by the sun's rays were beyond comparison the greatest. M. Reaumur conceived the grains in question to be the eggs or spawn of some fish, but whether of the buccinum, or any other spe- cies, he was uncertain; and under this uncer- tainty he proposed calling them " Oeufs de pour- pre," eggs of purple. The colour which they produced, was at least equal, if not superior in beauty, as well as durability, to that of the buc- cinum : though the colouring liquor of the lat- no PHILOSOPHY OF ter was much thicker than that of the purple eggs, and not liable to pass through the different changes of colours so quickly as that of the eggs, excepting when diluted. Having put some of this diluted liquor into two glasses, and placed one of them in contact with the sun's rays, and the other near the fire, the former became pur- ple without any sensible addition of heat, whilst that which was at the fire had only began to ac- quire the first shade of colour, though it was sen- sibly hot : and indeed he always found the co- lours produced by the sun to be more beautiful than any others ; a circumstance which he endea- vours to explain, by supposing its rays to act mechanically, in changing the figures or arrange- ments of the particles of the liquor, in the same way as he supposed the wind to change them, but with more efficacy. j M. Reaumur perceived the same disagreeable smell of garlick from the liquor, whichMr. Cole had before mentioned ; and he found it the more insupportable, as the heat of the sun or fire was the strongest. The colour of the liquor was not produced, or affected either by vegetable alkali (carbonate of pot-ash), or sulphuric acid; but a very little corrosive sublimate of mercury, put into the diluted liquor of the buccinum, instantly rendered it blue, and the colour was soon preci- pitated with the mercury, to the bottom of the vessel, leaving the liquor colourless; an effect PERMANENT COLOURS. 141 which, as usual, he endeavoured to explain me- chanically, by supposing the sublimate to consist of little globules, stuck round with sharp points^ which enabled it to change the arrangement of the particles of the liquor more expeditiously, even than he had supposed it done by the wind. He found that the liquor of the buccinum tasted as hot as the hottest pepper, whilst that of the purple eggs was saltish; but even this was so viscid, that it did not ruu, when topically ap- plied to linen, &c. ; and as the eggs were, ac- cording to M. Reaumur's account,* so plenti- ful, that one man might collect half a bushel of them in a (e\v hours, there certainly is reason to think, that they would be highly useful, at least in calico printing, where their liquor might be applied, with the greatest facility, both for pen- ciling and printing, as a substantive topical co- lour, and where a small quantity would go far, especially upon fine muslins. But at that time the art of calico printing had not been prac- tised in France, and therefore nobody thought, of applying Mr. Reaumur's discoveries in that way. About the beginning of the year 1 736, M. Duhamel found the purpura, (the buccinum only having been discovered by Cole and Reaumur,) in great abundance upon the coast of Provence ; f ftn the Mem. de I'Acad. Royale des Sciences, &:c. an. 17 11. M2 PHILOSOPHY OF and observed it to agree very well with the description thereof, given by Rondel et. lie found the viscid colouring liquor of the fish to be white, except in a few instances, where it was green, which he suspected to be some mor- bid effect. The white liquor being exposed to the sun's rays, assumed the following colours ; 1. a pale yellowish green ; 2. an emerald green ; 3. a dark blueish green ; 4. a blue, with a begin- ning redness ; and 5. a purple ; and these changes all happened in less than five minutes. Linen wetted with the white liquor, and left all night in a dark room, had only become green in the morning ; and this was also the case of linen wetted in like manner, and exposed all night in the open air, but shaded from the moon's light. A piece of linen, wetted in the same manner, being partly exposed to the sun's rays, and part- ly hid by a crown-piece of silver, the former part became purple, whilst the latter was only green. Other linen so wetted, being heated in a Duch oven before the fire, or upon a hot iron, became of a dark green, but not purple. The fumes of burning sulphur only produced a dark green ; and this was moreover the case with the different coloured rays of the sun, applied separately by a prism. Wishing to see whether evaporation tended to colour the white liquor, Mr. Duhamel put some of it into a phial well stopped ; and, upon exposing it to the sun, PERMANENT COLOURS. 143 found the liquor become cf a reddish purple almost immediately. A piece of linen wetted, and stuck upon the back of a plate of polished glass, three lines in thickness, and exposed to the sun's m S became purple even before it had dried. Three pieces of linen so wetted, being covered, one with white, a second with black, and the third with oiled paper, the last soon became of a good purple colour, but the others only became green. Linens wetted in like man- ner, and exposed to the light of the moon, or of burning wood or candles, became green, but not purple. Exposure to the sun's rays always pro- duced the purple, and most expeditiously, when its light and heat were strongest, the sun-shine of the month of March having proved much more efficacious than that of January or Febru- ary. The purple was instantly produced by the sun's rays, collected under a burning glass. The liquor which M. Duhamel suspected to be morbidly green, became purple sooner than the white liquor ; a circumstance which does not indicate its greenness to have been the effect of disease. In linens where the colour had stopped at the green, without reaching the pur- ple hue, it was soon carried off by boiling with soap, fossil alkali, alum, &c. which the colours that had already become purple, withstood for a long time, and were not hurt by the fumes of burning sulphur. See Memoirs of the Royal Academy of Sciences, &c. 17 36, U4 f HILOSOPftt OF Until MY. Cole had discovered the buccinurn, no adequate conceptions could have been formed of the changes, through which its liquor, and that of the purpura, became purple. Aristotle and Pliny had, indeed, both given intimations of its being primitively white; arid Pliny had slightly mentioned one of the intermediate colours, the green.* That the other changes were not more distinctly noticed, must be ascribed to the little attention then bestowed upon subjects of natural philosophy, and per- haps to a want of sufficient communication with the purpurarii piscatories, by whom the liquor was collected and salted. And there can be no doubt of the identity of the shell-fish employed by the ancients, and those discovered by Cole, Reaumur, and Duhamel, or of the similitude of their changes, and of the means by which their several liquors became purple. In a collection of Anecdota Gneca, lately published by M. d'Anse de Villoison, from MSS. preserved in the King's library at Paris, and that of St. Mark, at Venice, there is a description of the manner of catching the shell-fish, employed for the purple dye, written by an eye-witness, Eudocia Macrcm- bolitissa, daughter of the emperor Constantine the eighth, who lived in the eleventh century, while * <( Color austerus in Glauco, et irascenti sitnilis mari." Lib. ix. cap. 3(5. PERMANENT COLOURS. 145 the knowledge and practice of dying that colour For the use, ami at the expence, of the Greek emperors still subsisted ; and from which it manifestly appears, that in those times, as well as in ours, the purple did not acquire its dua lustre and perfection until it had been exposed to the sun's rays. Those who are duly acquainted with the more recent chemical discoveries, can only hesitate between two ways or' accounting for the changes through which the liquors of the purpura and buccinum become purple ; I mean, whether it be by gaining oxygene from the atmosphere, like indigo, when it acquires its blue colour ; or by the separation of a redundant portion of oxygene, naturally combined for some unknown purpose, in the liquor of these shell -fish ; and in that particular state which will not admit of its being separated without the application and assistance of light ; as is also the case of horned silver, rendered purple by the sun's rays ; of vegetables, rendered green by the same cause, after they had become white by growing in dark- ness; of peaches, purple grapes, and other fruit, which never acquire their proper colours by any degrees of heat, but always remain white or green, if shaded and secluded from the con- tact of the sun's rays. A very few experiments, which I hope to have an opportunity of making hereafter, would ascertain this point beyond' the 146 PHILOSOPHY OF possibility of doubt; though in fact there is, I think, at present, very little room to doubt but that the purple, under consideration, is produced in the last of the two ways just mentioned.* Such were the conclusions which I had form- ed, and published in 1794; and it will soon be found that they have since been completely verified, by the most decisive experiments. In the month of September, 1803, Mr. Samuel Richardson, of Cowbridge, in Glamorganshire, at the request of my truly respectable friend Dr. Cheston, of Gloucester, obligingly procured and forwarded to me a large parcel of shell-fish, (apparently of that species with which the experiments of Mr. Cole had been formerly made,) belonging to the genus of Buccinum (commonly called whelks) and agreeing in their specific character, with the Buccinum lapillus. of Linnaeus. I had no difficulty in finding and extracting the colouring matter of these Testacca, which in appearance and consistence very much re- sembled well-formed pus, and was collected to the amount of two or three drops in a little whitish cyst, placed transversely under, but in immediate contact with the shell, and * M. Berthollet on the contrary appears to believe that the effect in question, is produced by a farther combination of oxy- See Elements, &c. torn, i, p. 144, last Edition. PERMANENT COLOURS. 147 near the head of its inhabitant the Umax. The white slightly yellowish colour of this cyst, and of the matter contained therein, rendered it perceptible by close inspection through the semitransparent substance of the shell, though the latter was not furrowed or channelled, where the cyst came in contact with it, as I had sup- posed from Mr. Cole's description. This pus-like matter, either diluted with an equal portion of water, or undiluted, being applied to bits of white linen or calico, became purple after going regularly through the inter- mediate colours mentioned by Mr. Cole, and in the same order. And these changes were com- pleted in a very few minutes, when the sky was serene, and the bits of linen or calico were, in summer, fully exposed to the sun's beams ; and more especially with the diluted matter; for the undiluted, being often confined with too muck body % in a small space, was not so soon thoroughly penetrated and changed by the solar rays. I mixed different parcels of this matter with each of the several alkalies, both in their mild and caustic states, and having applied them to linen and calico, I found that instead of retarding the progress of these changes, and the ultimate effect of a purple colour, they rather pro- duced an acceleration thereof: and this was the case in a more remarkable degree, when the mat- ter in question was mixed with alcohol, or the i. a 148 PHILOSOPHY OF volatile essential oils of cajeput, turpentine, lavender, &c. or with muriatic acid : on the con- trary, these changes appeared to he considerably retarded, by the admixture of nitric acid, though it did not hinder them from ultimately taking place. Sulphuric acid had a similar effect, but in a lesser degree, as had the citric, and acetous acids, and that of tartar. The same matter ap- plied to muslin, and put into a glass filled with hydrogene gas, and closely stopped, being expo- sed to the direct rays of the sun, went through all the before-mentioned changes in one third less time than usual ; whilst similar matter, con- fined in the same manner with oxygene gas, and exposed at the same time, underwent these changes more slowly : and nitrogen gas employ- ed in the same way, and at the same time, had no apparent influence upon them. These, and other experiments, rendered it at least highly probable that a separation, and not an addition, of oxygene accompanied and contributed to the attainment of the purple colour in question. But before I had made all the experiments which seemed necessary to ascertain the fact, my attention was unavoidably diverted to other objects ; and fearing that my whelks might die, and become unfit for other experiments before I could find leisure to make those which I had projected, I broke the shells of at least one hundred of them, and after extracting their PERMANENT COLOURS. H<> colouring matter, and applying it undiluted to bits of calico and muslin, I placed these bits separately, and as expeditiously as possible, each between two leaves of a large blank folio book, and afterwards kept it closely shut, to exclude the light : believing, though the matter in ques- tion had not been allowed to become dry before it was shut up in this way, that so much of its moisture would be absorbed by the paper, as to obviate any putrefactive process, and that if this could be obviated, the matter in question would continue fit for my experiments, so long as it should be kept secluded from light. And in these respects my belief appears to have been well founded, since even -now (August, 1812,) when almost nine years have elapsed, I find that the bits of muslin so shut up, (of which a score are still remaining) exhibit only the yellowish spots given by this matter as when first applied to them, and that they are as capa- ble as ever, of passing through the usual changes of colour, and finally becoming purple, if assisted by the sun's rays. They do this indeed more slowly, when exposed without being Jirst moist- ened; but after being dipped in water, the changes succeed as regularly, and quickly, as they have usually done with matter just taken from its natural receptacle, and the experiments which I am now about to relate, were all made with the matter which had been so applied, either * 150 PHILOSOPHY OF to muslin or calico, and secluded from light, more than seven years. 1st. A bit of calico, so impregnated and secluded from light, was put into a very small white glass phial, and the latter being filled with strong nitric acid, which had been diluted by about five times as much water, it was stopped and exposed to the rays of the summer's sun : and in about twice the usual time, as nearly as I could judge, the yellow spots became first green- ish ; then of an apple green, and afterwards of a deep grass green colour : but here the progress appeared to stop so long, that I began to think it would proceed no farther : at length, however, a blue tinge became evident, then a deep blue, and finally a purple ; so that the oxygene of the nitric acid, though it manifestly retarded the usual changes, did not hinder their ultimate accomplishment. This experiment was repeated, with a substitution, first of diluted sulphuric, and then of citric acids, instead of the nitric ; and with a similar obstruction to the usual changes, though it was of less duration ; this also happened with the acid of tartar. A simi- lar experiment being made with widiluted muriatic acid, the several changes terminating in a fine purple, were all completed, and, as I thought, in little more than half the usual time. This experiment was repeated with bits of impregnated muslin, by substituting caustic PERMANENT COLOURS. 151 solutions of potash, soda, and ammonia separate- ly, for the acids before mentioned, and in all of them, the purple colour was produced, after the usual changes,in full perfection, and, as I thought, with greater celerity than they had formerly been with the matter just extracted from the buccinum ; and this also happened with muslin immersed in olive-oil. A similar bit of muslin put into a phial com- pletely filled with a solution of tin, in muriatic acid, which had been recently made, and was at the minimum of oxidation (if not destitute of oxygene) upon being exposed to the sun's rays, became purple with great celerity, after passing through the usual succession of colours : and this was the case with another bit put into a phial and filled with the oxymuriatic acid (chlorine of Davy) as concentrated as any which I could pro- cure. This last result appeared to me the more extraordinary, because I had previously seen this acid exert its destructive influence, upon the purple of the buccinum produced in other ways, almost as quickly and efficaciously, as it is known to do upon colouring matters generally : and I therefore prolonged this experiment, by remov- ing the phial, when the purple was completely formed, to a situation where the direct rays of the sun could not reach it; and there I found, after a few hours, that the very same acid which appeared To have accelerated the production of 152 PHILOSOPHY OF this purple, had afterwards annihilated the colour so produced, leaving the muslin perfectly white ! That I may not unnecessarily prolong this account of my experiments, I will omit several of lesser importance, and proceed to a recital of tzvo, which I think conclusive, in regard to the problematical part of this inquiry, viz. First, — Into a flint glass phial, more than half-filled with quicksilver, (strained through leather,) I conveyed a triangular hit of fine muslin, impregnated, dried, &c. as before men- tioned ; and having attached one corner thereof, by compressing it between the glass stopper, and the opposite inner surface of the mouth of the phial, I inverted the latter, so that the quick- silver sunk down to its neck, pushing the muslin (which by this attachment was hindered from ascending, and which had been previously spread,) closely upon one side of the inner surface of the phial, the other surface being in immediate contact with the quicksilver, which rose an inch above the muslin ; so that the latter, was completely secured from the access of atmospheric air ; that which the phial con- tained, being forced by the superior weight of the mercury, into the space above it. Thus circumstanced, the phial (in the month of August,) was exposed to the sun's rays, that side of it, upon the inner surface of which PERMANENT COLOURS. 153 the muslin was applied, being turned towards them : and in this situation I observed the muslin, or rather the colouring matter of the buccinum, to pass through all the shades of green and blue, and become a full reddish purple with as much celerity, as similar matter in a dried state, had commonly done, when exposed to the sun's beams, with the free access of atmospheric air. Though it appeared difficult to devise any ex- periment more decisive than this, I made a second, by filling with quicksilver, a small cylindrical glass tube, 34 inches long, and closed at one end; and having stopped the orifice with my fmger, I inverted the glass upon a china cup, containing more quicksilver, and then, withdraw- ing my finger, the mercury sunk, and lefta vacuum above it, of about four inches in height: I then placed a bit of fine muslin impregnated, dried, " should, according to the prin- ciples of the French nomenclature, be called phosphorous acid") emits an offensive alliaceous smell, very much like that of the colouring mat- ter of the buccinum, when it becomes purple. The last, or that part of it which gives the smell of garlic, readily mixes with water, and strong- 156 PHILOSOPHY OF ]y impregnates it with this odour, as I have found by many experiments; and in this re- spect it also agrees exactly with the volatile compound which gives the alliaceous odour from phosphorous. I repeated Reaumur's experiment with corro- sive sublimate of mercury, and found that the purple which resulted, partook more of the blue tint than usual, and this appeared to be the case when the colouring matter of the huccinum was mixed with sulphate of iron. Pliny, as my readers will have seen, represents the purple colour obtained from the buccinum, as not being permanent, without a mixture of that from the purpura; but on this point he was certainly misinformed, it being of itself the most durable of all animal colours. I found that it was not sensibly affected, even upon fine muslin, by being wetted with undiluted oxymuriaticacid, though when immersed in a phial filled with this liquor, it soon disappeared, as I believe would happen to almost every other animal or vegetable colour. I found also that undiluted oil of vitriol dropped upon a bit of calico, which had been made purple by the matter of the buccinum, did not destroy the colour, though it produced a tinge inclining more to the blue. Highly concentrated and smoking nitrous acid, applied to a similar bit of calico, changed the purple to a yellow colour, which became very PERMANENT COLOURS. 15? lively and beautiful, upon being rinced in a solu- tion of potash. Thiuking it not unlikely that this change might have resulted from a combina- tion of oxygene, with the colouring matter, rather than from an irreparable decomposition of it, I exposed the yellow in question to the direct action of the sun's rays, to see whether their deoxygenating power would reproduce the purple, but no such effect ensued ; the yel- low remaining, and seeming to be permanent. Strong muriatic acid applied to a similar bit of calico, appeared to have no effect upon the pur- ple colour; and single aquafortis changed it less than the much weaker oxymuriatic acid. — But I will proceed no farther with my observations, believing that I have now sufficiently explored and elucidated this hitherto abstruse subject. Some of my readers may indeed think that I have been too minute in my statements concern- ing it. But to me, the colouring matter under consideration, lias appeared to deserve my utmost attention, because, (independently of the vene- ration with which it was contemplated by the ancients) its properties are more extraordinary, more interesting, and more instructive, than those of any other. It is strictly, and preeminently, in titled to the distinction of a substantive colour, as it may be permanently fixed, even upon linen and cotton, by the most simple application, and without any preparation or admixture whatever ; 158 PHILOSOPHY OF • and it is admirable, for the singular constancy with which it proceeds, through the series of intermediate colours, (according to their pris- matic arrangement) until it has permanently fixed itself, and attained that purple tint, which the author of nature, for some unknown pur- pose, has fitted it to display ; and all this, in spite, if 1 may so express myself, of many powerful chemical agents, whose utmost influ- ence extends only to retard, for a few hours, the ultimate accomplishment of this its destiny. The celebrated Fontenelle, in giving (as Secre- tary of the Royal Academy of Sciences at Paris) his account of Reaumur's discovery, began by observing, that not only more things were found in modern, than had been lost in ancient times, but that it was even impossible for any thing to be lost unless mankind were willing that it should remain so; it being only necessary to search in the bosom of mature, where nothing is annihilated ; and that to be certain of the possibility of a thing's being found, was a considerable step towards finding it. But before the buccinum and purpura were found by Cole, Reaumur, and Duhamel, America had been dis- covered, and new dying materials thence obtain- ed, superior in beauty, and especially in cheap- ness, to those so highly valued in ancient times ; though it must be confessed, that no other sub- stance will afford a substantive purple of equaj PERMANENT COLOURS. 159 beauty and durability, and capable of being topically applied to linen and cotton with 30 much simplicity and expedition ; and for these reasons it seems probable that the discoveries of these Gentlemen might still be rendered beneficial in staining or printing fine muslins, for which but little colouring matter is required. And indeed, there was a species of buccinum found more than a century ago near Panama, on the coasts of Guayaquil and Guatemala, of which constant use appears to have been made in those countries, for the dying or staining of cotton, as Jussieu, the elder, Thomas Gage, and others have mentioned. Don Antonio Ulloa, in particular, says, " they are something larger than a nut, and contain a juice which, when expressed, is the true purple ; for if a thread of cotton or the like be dipped into this liquor, it becomes of a most vivid colour, which repeated washings are so far from obliterating, that they rather improve it ; nor does it fade by wearing." " This precious juice," continues he, "is extracted by different methods; some take the fish out of the shell, and laying it on the back of the hand, press it with a knife from head to tail, separating that part of the body into which the compression has forced the juice, and throw away the rest." This being done, " they draw threads through the liquor which is the whole process ; but the purple tinge does not 160 PHILOSOPHY OF appear immediately, the juice being at first of a milky colour, from which it changes to a green, and, lastly, to this celebrated purple." See the translation of his account of the voyage to South America, &c. vol. i. p. 26s <). Snails, with the same property, exist in various other parts of the world. Catesby, in describing the Bahama islands, (vol. i, p. xliv.) mentions among the shells there, the '■" Buccinum brevi rostrum muricatum, ore ex purpuro nigricantc dentato," adding " these shells stick to rocks a little above low water, and are consequently a short time uncovered by the sea. They yield a purple liquor, like that of the murex, which will not wash out of linen stained with it." Josselyn also, in his " New England Rarities discovered," p. 37, says, •' at Paschataway, a plantation about 50 leagues by sea, eastward of Boston, in a small cove, called Baker's Cove, they found this kind of muscle, which hath a purple vein, which being pricked with a needle, yieldeth a perfect purple or scarlet juice, dying- linen so that no washing will wear it out, but keeps its lustre many years : we mark our hand- kerchiefs and shirts with it." Mr. John Nieu- hoff moreover relates, that " abundance of purple snailsarefoundin the islands over gainst Batavia." " They are boiled (adds he) and eaten by the Chinese, who have a way of polishing the shells, and pick out of the middle of the snail a certain PERMANENT COLOURS. Id purple-coloured substance* which they use in colouring, and in making red ink. In the fiftieth volume of the Philosophical Transactions, Dr. J. A. Peysonnel, F. R. S. describes what he calls the naked snail pro- ducing purple, (" Liinax non cochleata, pur- pur ferens,") as being found in the seas of the Antilles, and " precious for the beauti- ful purple colour it produces in the same man- ner that the cuttle-Iish produces its ink." " There is (continues he) a hollow in the back of the animal where the canal, filled with a reddish juice, passes out, carrying it to a fringed body like a mesentery ; and it is there the pur- ple juice is brought to perfection." " When the animal is touched, he makes himself round and throws out his purple juice as the cuttle-fish does his ink : this juice is of a beautiful deep colour; it tinges linen, and the tincture is dif- ficult to gr. Roxburgh.* " In a few hours, more or less, according to circumstances, a slight, motion begins to per- vade the body of the liquor in the vat ; the fculk increases considerably, with some addi- tional heat ; ah - bubbles are generated, some of which .•remain on the surface : these gradually collect infco patches of froth ; a thin violet, or copper-coloured pellicle, or cream, makes its ap- * As a supplement to the former edition of this volume, I was induced to publish (with some observations of my own) an abstract of a MS. which had been put into my hands at the East India House, containing an " account of a new species of nerium, the leaves of which yield indigo," &c. ; with a second part, containing " the result of various experiments made with a view to throw some light on the theory of that beautiful production : and an appendix containing a botanical description &f a second new indigo plant ; the whole illustrated with draw- ings, and addressed to the Honourable Sir Charles Oakley, governor, and president in council at Fort St. George, to be trans- mitted, to the Court of Directors of the united East India Com- pany, and committed to their protection," &c. By William Rox- burgh, M.D. But as the whole of that MS. with some few additions and explanatory engravings, has been lately, (and in some degree upon my suggestion) printed as a part of the 28th volume of the Transactions of the Society of Arts, Manufac- tures, and Commerce, I am enabled to abstain from a repub- lication of my former abstract^ though I shall at the proper places, avail myself of the most interesting of Dr. Roxburgh's facts; taking them from this last-mentioned volume of the Society of Arts, &c. to which my references will be made. 2 PERMANENT COLOURS. 175 pearance between the patches of froth; soon after, the thin film which forms the covering of the bubbles that compose the froth, begins to be deeply tinged with fine blue. The liquor lias from the beginning, been acquiring a greeo. colour, and now it will appear, when viewed falling from one vessel into another, of a bright yellowish green, and will readily pass the closest filter, until the action of the air makes it turbid ; a proof that the base of the colour is now perfectly dissolved in the watery menstruum: this is the time for letting off the vat. If suf- fered to remain, the bulk begins to disminish, and returns to its original dimensions ; how- ever, the fermentation continues ; there is stilt much intestine motion through the vat, and large quantities of froth are formed. Hitherto the peculiar meU of the plant has prevailed, but now it becomes very offensive, something like that of animal matter beginning to pu- trify. As fermentation goes on, the smell becomes more and more offensive, and the quantity of airs discharged less and less, until absorption takes place." This first macerating and fermenting/jrocmj occasions an extraction of the indigo basis, and an impei feet oxygenation of it: but in other re- spects I do not know that it is of any impor- tance, to the production of indigo. Other plants, in similar circumstances, would ferment m PHILOSOPHY OF With an evolution of carbonic acid gas; and doubtless the various extractive matters of the indigo plant, participate and co-operate in pro- ducing the appearances just described by Dr. Roxburgh; who has, however, ascertained that in the first part of this process, there was a great absorption of, or from the atmosphere; (the free access of which was indispensably ne- cessary to the fermentation) and this absorption doubtles consisted principally of oxygcue. He found, moreover, that as soon as the bulk of the mass began to be enlarged, a disengagement of airs took place, which he describes as being fixed, pure, and impure," (meaning, I presume, carbonic acid gas, oxygene, and perhaps hydro- gene.) " But, continues he, about the time that the bulk of the vat is greatest, the fixed air is dis- charged purer, and in larger quantities than at any prior period." " I tried," he adds, " every means I could invent, to detect the volatile alkali, that I was led to expect, but without the smallest appearance of success, at any time." If, a*s soon as the fermenting liquor becomes green, an alkali be added to it, a precipitation, says M. Dutrone, will take place, " d'une fecule verteextremeinent belle"; and at a more advanc- ed state of the process, which he calls t; la fermentation putridc," alkalies, according to his account, will precipitate a " fecule qui porte une couleur bleu de ciel ties le gcre.'' 2 PERMANENT COLOURS. 177 The fermentation being completed, the green coloured liquor is drawn off, from the steeper, into the beating vat, or receptacle, (which the French call batterie,) where it is violently agi- tated, commonly by machinery, during one, two, or three hours, according to the means adopted, and the force with which they are employed; the effect of this agitation is analo- gous to that of churning, for by promoting a farther oxygenation of the basis of indigo, it renders the latter insoluble, in the liquor, which had previously held it, dissolved ; and thereby causes it to granulate, or collect into small par- ticles, or little floculce, suspended, but not dis~ solved, in the aqueous menstruum which still re- tains, in solution, the other matters extracted from the indigo plant, and by so retaining them, enables the manufacturer to separate the former from the latter, by adding lime water, or some other suitable precipitant, which is to be mixed with the liquor, as soon as a distinct granulation becomes manifest.* * Dr. Roxburgh has believed, that the basis of indigo, du- ring the fermenting process, was held in solution by carbonic acid, and that agitation and precipitants were afterwards useful, the former by extricating this acid, and the latter by absorbing it. That such effects are produced, may be presumed by the discharge of carbonic acid gas, which is manifest during the agitation of the liquor, and by the cessation of that discharge, when either lime water, or caustic alkali is added. But that this agitation answers another, and more important end, N 178 PHILOSOPHY OF During this last agitating, or oxygenating process, " fixed air, says Dr. Roxburgh,, conti- nues to be discharged, with pure and impure airs; but still nothing, like volatile alkali." But when the precipitant is added, " from that instant an absorption of air takes place ; and after the liquor has settled a little, a candle will burn freely close to its surface." The most efficacious precipitants hitherto em- ployed are pure well-burnt lime water, and the • different alkalies, especially when in their caus- tic state ;* and some of these in suitable proportion may be proved even from some of Dr. Roxburgh's experiments to be presently noticed ; and that lime water may act as a precipitant, otherwise than by absorbing carbonic acid, is certain, from its well known power of throwing down many colouring matters, when they are held in solution, where no carbonic, or other acid is present 5 in such cases the lime acts by its par- ticular affinity for these colouring matters, in the same way in which, as Dr. Roxburgh observes, " a solution of tin in aqua regia (in a very small proportion) gives a large produce of light blue precipitate," when added to the liquor in question. Alum acts in the same way, but by throwing down at the same time the other extractive matters of the plant, it debases the quality of the indigo. * Concerning the expediency of precipitants, Dr. Roxburgh delivers the following opinion : " The coloured liquor, im- pregnated with the first principles of the drug, (its base) whe- ther acquired by fermentation, or by a scalding heat, will, with- out the least of our assistance, if only exposed to the open air, and particularly if with a large surface, in a short time begin to part with its colour, which will fall to the bottom in minute PERMANENT COLOURS. 179 being well mixed, and the liquor left at rest for six or eight hours, the blue-coloured matter will commonly be found to have all subsided to the bottom, leaving the supernatant liquor of a clear brandy, or Madeira wine colour : when it appears more or less green, or olive-coloured, grains of fine blue indigo : agitation will hasten the separation and precipitation much, and cause the produce to be larger. Heat has nearly the same effect, though in a less degree, ex- cept when joined with agitation, in which case the two act more powerfully than either alone. The ipidigo procured by these means is good, if the process has been properly conducted j precipitants are not therefore absolutely necessary for the pro- duction of indigo, but if well chosen, and in a proper proportion, they forward the operation much, causing a larger produce than could be had without them j and 1 have reason, from a variety of experiments, to say, that the quality is by no means injured in consequence." — Dr. Roxburgh thinks lime water preferable to any other precipitant ; alkalies, he says, " answer the best when made caustic, but even then lime water gives a purer indigo, though probably not in quite so great a quantity." He adds that if lye perfectly caustic be added, before the liquor has been agitated, or before any granulation has taken place, the extrac- tive matters of the plant will generally be precipitated first, in the form of a dirty pale yellow fecula : in the mean time the supernatant liquor gradually acquires from the surface a deep blue colour, soon becoming turbid, and lastly the blue precipi- tate of real indigo will be formed over the first." P. 281, and feq. Precipitants, therefore, should not be added to the liquor until the indigo basis has been sufficiently oxygenated ; which, among other appearances, may be known by a change in the colour of the froth on its surface, which, after appearing blue, becomes colourless, because the blue matter which gave it that appearance being no longer dissolved, subsides from the froth. N 2 ISO PHILOSOPHY OF we may conclude the separation and precipitation of the indigo have been but imperfectly per- formed : this happens indeed but too often, and Dr. Roxburgh conceives " it to be owing to the presence of fixed air, (carbonic acid gas) still adhering to, and keeping dissolved a portion of the base" of indigo. I think it more proba- ble, however, that a part of the basis of the indi- go is, in such cases, hindered by the presence of carbonic acid, from attracting and uniting to itself a sufficient portion of oxygene to cause a separation of it by precipitation from the other extractive matters yielded by the plant ; it having been found, that by renewing the agitation, of such green or olive-coloured liquor, and adding precipitants to it afterwards, more indigo may be obtained.* * As the profit of the indigo maker greatly depends upon his knowing when to stop the fermenting, as well as to the agitating, process, it may be proper that I should subjoin a few observa- tions upon each. The fermentation begins soonest when the weather is hottest, and when the vat has been recently employed for the same purpose ; as it then retains a kind of fermenting leaven. If the fermentation be stopped too soon, a consiJerable part of the colourable basis will be left unextracted, and lost in the plant-, to avoid th*is loss, handfuls of the twigs and leaves are frequently drawn from the vat, that it may be ascertained whether they are become of a pale yellow, and the young tops made tender. Re- gard should also be had to the colour of the liquor, which, so long as the fermentation has been deficient, will have only at- tained a yellowish green, with a copious greenish froth, capa- PERMANENT COLOURS. 181 Dr. Roxburgh ascertained by experiments, which are minutely described at pages 278— 281, of the volume before mentioned, that some ble of being easily dispersed by a few drops of oil, which is not the case when the fermentation has been carried too far. In this last event, the froth or scum generally subsides, and the green colour of the liquor will lose its brightness, appear brownish on the surface, and become turbid, from an excess- ive dissolution and extraction of the various matters belonging to the plant. The liquor which has suffered in this way, cannot bear much agitation afterwards, without farther injury to the indigo resulting from it ; which will become either blackish or ofadull,*/ate colour, and be found very little susceptible of either granulation or precipitation ; and even with moderate agitation, the liquor which has undergone this excessive fer- mentation will never afford good indigo. But where the fer- mentation has, on the contrary, been deficient, though the quan- tity of indigo to be obtained will be small, the quality may be improved by a greater degree of agitation. When too little of this last is given to liquor which has not been fermented sufficiently, the indigo will manifest a coarse grain, and not only prove less in quantity, but its blue colour, instead of the cop- pery gloss, will retain a greenish cast. I will here add, in re- gard to the precipitants, that the Javanese, as M. de Cossigny relates, avoid the want, and use of them, by first fermenting the indigo plants, and then boiling the liquor for a little time before it is agitated. It is not, I believe, the practice to put water a second time upon the indigo plants in the fermenting vat, in order to extract or wash out, any remnant of the in- digo basis, left in, or adhering to the plant, after the fermented liquor has been drawn off; but I am persuaded, that it this were done, and this washing, or second exiract, were ad ea 10 the first, a considerable portion ot indigo might be outlined, which I believe to have been hitherto lost. 182 PHILOSOPHY OF of the green indigo liquor, taken, when just fit to be drawn off from the fermenting, into the agitating vat, and impregnated with carbonic acid gas, (in Dr. Nooth's apparatus,) would afford no granulation or precipitation of indigo. This was also the case with liquor obtained by scalding the leaves of the indigo plaut in large earthen bottles. The liquor thus obtained, always became of a yellowish green, and the bottles containing it, being inverted in a large vessel of water, the liquor remained unchanged for a month ; but, being taken out, and atmospheric air freely admitted to the liquor, greenish blue veins were observed to spread, from the surface downward, until the xvhole became blue ; and then a precipitation of indigo soon commenced. This experiment was often re- peated with the same result ; and Dr. Rox- burgh justly infers from it, that carbonic acid is not the agent, by which the colouring matter of indigo " is separated from its menstruum." Some of the same green liquor, being impreg- nated with nitrogene, from iron filings, and diluted nitrous acid, (in Dr. Nooth's apparatus) a violet-coloured film was produced, after some hours; but no other change took place, until the admission of atmospheric air, when the usual granulation and precipitation of indigo, soon followed. Some of the same green liquor, being impreg- nated, in the same way, with hydrogene, from PERMANENT COLOURS. 183 iron filings and diluted sulphuric acid, it " was quickly covered with much of a deep violet- coloured scum, but no decomposition took place, till the atmospheric air had obtained access to the liquor, when it quickly became of a deep greenish blue, and let fall a considerable proportion of precipitate, which, on drying, turned out to be the most beautiful indigo." In addition to these experiments, Dr. Rox- burgh tried repeatedly, with the same green liquor, admixtures of lime water, volatile alka- li, caustic lye, stale urine, prussiate" of potash, &c. and they all concurred, says he, to " prove clearly, that the most powerful precipitants, added to these liquors, cause no decomposition , without the help of the open air." Though Dr. Roxburgh had thus ascertained, the indispensable necessity of something, obtained from the open air, to produce a granulation, and precipitation of indigo, and though he had also ascertained that this thing, could not be either carbonic acid gas, or nitrogene, or hy- drogene, or ammonia ; he did not suspect it to be oxygene, until the former edition of this, my first volume, had fallen into his hands ; then however, (as I had predicted) he, with lauda- ble candour, relinquished his belief of the sup- posed agency of phlogiston, in producing these effects ; and declared himself convinced, that " oxygene is the colouring principle of indigo."* * The following is extracted from a letter written by Dr. 184- PH1L0S0PHY OF M. Kerthollet seems not to have well under- stood the effect of some parts of the process lately described. He says, torn. ii. p. 42, that Roxburgh, to Robert Wissett, esq. and dated Calcutta, 29th of October, 1797. " I have seen the heads of my essay on indigo published, and commented upon, by Dr. Bancroft. In consequence of seeing so good an use made of it, I am encouraged to send to your care, by Mr. Brown, the surgeon of the Albion, a pack- age of a colouring drug, which I do not imagine has ever reached Europe, viz. the coloured tubes of the blossoms of Nyc- tanthes arbor tristis, of Linnaeus. The Hindoos use them to give a most beautiful orange colour to cotton cloths ; but with them the colour soon fades. I will thank you to give the parcel to Dr. Bancroft, and also beg of you to inform him, that I am now a convert to his opinion, viz. that vital air , or oxygene, is the colouring principle in indigo. — The hot water process begins to be used over these provinces, by some of the best manufacturers j with it they can make indigo, when the wea- ther is too cold for the usual process of fermentation, and it gives a more beautiful and lighter indigo, like theguatamala, or fine Spanish flora. I send you a sample of some made by Mr. Pope, of Cossimbuzar, a most valuable farmer." When Dr. Roxburgh was lately in Europe, he obligingly left with me, not only samples of the indigo here mentioned, (and which is truly excellent,) but of many other sorts, ma- nufactured in different ways, from different kinds and species of vegetables yielding indigo, and with different precipitants, &c. ; all serving either to confirm or illustrate particular facts respecting tins interesting subject : but a distinct account of them would occupy too much space. The scalding, or " hot water process," mentioned in the pre- ceding extract, had been previously recommended by Dr. Rox- PERMANENT COLOURS. 185 the atmospheric air docs not appear to inter- vene or partake in the fermentation, because there is a discharge of inflammable air. But it was fully ascertained by Dr. Roxburgh, that a copious absorption of air from the atmosphere, did occur ; and that oxygene did combine with the basis of indigo, in a considerable de- gree, during the fermentation, was manifested by the progressive change, which as usual con- burgh, and is, indeed, absolutely necessary to obtain indigo from the leaves of the nerium tinctorum, which affords none by fermentation, with water moderately warm. It is employ- ed, as the Doctor informs us, by " the natives throughout the northern provinces or Circars," (of Coromandel) and " in many parts of the Carnatic," in making indigo from the com- mon indigo plant. Among the advantages stated to result from it, are, — First, that, of a more complete and certain extraction of the basis of indigo, (by thus subjecting the plant to the action of water, heated to about 150°, or l60°, of Fahrenheit's scale,) than can be expected by the fermenting process ; with which the plant, as M. de Cossigny asserts, (Treatise on Indigo, p. 145,) will yield indigo, upon being fermented a second time.— Second, that of not injuring the health of labourers employed in it j the carbonic acid gas, and puuid miasma exhaled by it, being much less than by the fermenting process. — Third, that of requiring less agitation ; because the heat employed, greatly promotes the absorption and combination of oxygene. — Fourth, that of completing the operation, much sooner, so that it may be performed two or three times daily, upon a large scale. — Fifth, that of affording indigo, which dries quickly, without acquiring any bad smell ; and which " has never that flinty appearance common to fermented indigo j but in softness and levity is tike, or even superior, to Spanish flora." ^H 186 PHILOSOPHY OF stantly took place in the colour of the liquor, during the fermentation, until it acquired a full preen, and even blueish colour, the froth or scum becoming more or less blue, at the same time ; this change was not unknown to M. Ber- thollet, but instead of ascribing it to the oxy- genation of the indigo basis, he supposed it to result from the separation, or destruction of a yellow substance, which gave the plant a green- ish tint ; thus intimating, that the indigo had existed naturally of a blue colour in the plant, which certainly is not the fact. Some of the manufacturers cf this commo- dity, in the East Indies, shave lately purified their indigo, by taking it immediately from the small dripping 'cats, and boiling it in copper vessels, with water and fossil alkali, (soda) and afterwards carrying it to what are called the dripping tables, to undergo the treatment usual- ly employed for bringing it to the form of dry cakes. In this way those impurities which soda can dissolve, will be separated ; but others, on which it has no action, will remain. For these Dr. Roxburgh, as well as M. de Cossigny, have recommended the application of a diluted sul- phuric acid, which is said also to brighten the colour ;-}" as indeed it might be expected to do, f Among the samples of indigo, with which I was favoured by Dr. Roxburgh, are three extracted from theguatamala indigo PERMANENT COLOURS. 187 in the way that the colour of indigo dissolved by it for the Saxon blue, is brightened. Pro- bably the diluted acid, here recommended, will not be capable of diminishing the colouring matter of indigo, by dissolving and removing any part'of it : but if there were any danger of this, it would be advisable to substitute the muriatic acid, which could have no such effect, upon the indigo itself, though it is equally effi- plant, produced by seed, furnished by Colonel Kyd ; and they are stated to have been made on three successive days, viz. On the first, 104lbs. of leaves and shoots were cut at sun-rise, and by the usual process, they yielded six ounces, -^ij of very beautiful indigo ; i.e. at the rate of one ounce from about 17 lbs. of leaves and shoots : On the second day, 64lbs. of leaves and shoots, also cut at sun-rise, yielded in the same way, four ounces -J-g. of very fine indigo, or at the rate of one ounce from less than 161b. of the leaves and twigs. This indigo was washed with diluted sul- phuric acid, and three several times afterwards, with hot water j and though the produce was largest, the colour was a little the brightest : On the third day, 561b. of the leaves and twigs were cut at noon, the sun having shone upon them several hours ; they produced in the same way three ounces -^-i- of pure indigo i. e. one ounce from about iglb. of leaves and twigs. This indigo was, I believe, intrinsically the best, but like that of the first day, was not washed ; and the colour, though very beautiful, was in brightness a little inferior to that of the second day. Considering that the leaves and shoots were cut at noon, on the third day, when the rays of the sun might be expected to cause an exhalation of much aqueous vapour, it is surprizing that so little indigo was obtained. 188 PHILOSOPHY OF cacious, in dissolving all other matters likely to be mixed with indigo. It is, however, doubtful, whether any considerable advantage would result from these applications : they could add nothing to the tingent power of the indigo, though they might improve its appear- ance; but even this could not be done without such a diminution of its weight, as would coun- terbalance the latter advantage, and in gene- ral dyers know how to avail themselves fully of the tingent particles of indigo, whatever ex- traneous matter it may contain. Besides the several species of indigofera, already mentioned, and the Nerium tinctorium, (respecting which I must refer to Dr. Rox- burgh's publication, in the xxviiith vol. of Transactions of the Society of Arts, &c.) there are several plants which possess the basis of indigo, though the characters of some of them have not been well ascertained. This latter observation, however, is not applicable to a plant lately found by Dr. Roxburgh, to afford indigo, and by him denominated indigofera coe- rulea, (carneeli of the Tel in gas,) of which, he has also given a minute description in the vo- lume just mentioned ; and from the leaves of which, says he, " I have often extracted a most beautiful light indigo."* * I have now before me seven specimens of indigo, given to me by Dr. Roxburgh, and made by him from the indigofera PERMANENT COLOURS. 189 There is, moreover, a plant, belonging to a very different class, first mentioned as pro- ducing indigo, I believe bv Mr. Marsdeq, in his History of Sumatra, p. 78, under the name of taroom akkar. He describes it " as a vine, or creeping plant, with leaves four or five inches long, in shape like (those of) a laurel, but finer, and of a dark green colour ;" he adds, that " by reason of the largeness of the foliage, it yields a greater proportion of sediment." This plant Dr. Roxburgh considers as a species of asclepias, or swallow-wort, and has added to it the trivial or specific name of tinctoria. It appears to be nearly related to the nerium ; both belonging to the natural order of contort &, and both yielding their colourable matter from the leaves, most copiously, by hot water.* It was brought from Sumatra, and widely distributed in cocrulea, with the help of hot water, to extract the colouralle matter. They are similar to the same number of samples which the Dr. sent in 1793, with a description of the plant, to Mr. Ross, at Madras, to be forwarded to the Court of Direc- tors of the India Company, and are all very fine blue or violet indigo ; particularly four of the seven, which in appearance and effect, are, in my judgment, equal to the finest flora of guatamala. * Dr. Roxburgh has favoured me with three samples of indigo, which he obtained from the asclepias tinctoria, by hot water ; one is a very fine violet-coloured indigo ; another is more inclined to blue, and the third to purple ; the two last were specifically a little heavier than the first ; the worst of them, however, would, I think, be considered as worth 8s. per pound. 5 190 PHILOSOPHY OF Bengal, about the year 1791 ; is perennial, and easily propagated by layers, slips, or cuttings. I mention these particulars, because i shall have occasion to refer to them presently, in regard to a substance denominated barasat verte. Professor Thomas Martyn, mentions the galega tinctoria, as being the plant from which the inhabitants of Ceylon prepare their indigo, which yields a pale blue dye (see his edition of Millar's Gardener's Dictionary.) He also men- tions, on the respectable authority of Loureiro, that the spilanthus tinctoria, is cultivated in China, and Cochinchina ; that the leaves bruised, yield a most excellent blue colour, and a green, prepared by a method more easy than from indigo, and not inferior in brightness. Linnasus says, the Swedes obtain a blue colour from the scabiosa succisa, by treating it like the isatis tinctoria, or woad plant ; and I have been informed, that the cheiranthus fenes- tralis, or cluster-leaved stock gillyflower, is also capable of yielding indigo. This may be easily ascertained. Besides plants of the genus of indigofera in Africa, we have reason to believe there are several belonging to other genera, capable of producing indigo. Dr. Winterbottom says, " there is now no room to question that the blue dye, commonly used by the natives of the windward coast, is not indigo, but is obtained from a very different plant." He adds, " a few PERMANENT COLOURS. li)l roots of it, I am informed, have lately been planted within the settlement (of Sierra Leone,) so that an accurate description of it may soon be hoped for." Probably, this is the plant to which Professor Afzelius alluded, when, upon his return from Sierra Leone some years ago, he told me he had discovered a new plant pro- ducing indigo, of which he intended soon to publish a description. Dr. Winterbottom also states, on the authority of M. Isart, (Reise nach Guinea) that on the gold v coast, the negroes, instead of the indigo plant, infuse " the leaves of a species of bignonia, and the root of a species of taberniemontana, with a lye of wood ashes, to dye cotton blue." See his account of the Native Africans, vol. i. p. 97. The amorpha fruticosa, and the sophora tinctoiia, Lin. also afford coarse sorts of indigo. This production often differs greatly in re- gard to its specific gravity, some indigo being lighter than water ; and the lightest being always, and justly, the most esteemed ; because it is always the purest ; excepting only when the comparative weight has been increased, by very forcibly pressure, to separate the water, and accelerate the drying, that it may not be in danger of becoming mouldy.* Indigo is some- * Quatremere Dijonvilie asserts, and I believe truly, that indigo closely packed, and secluded from atmospheric air, will soon become hot, and undergo some degree of fermentation, 1 192 PHILOSOPHY OF times adulterated, by fraudulently adding to it various gummy, resinous, earthy, and mucila- ginous matters, and particularly an extract from the fruit of the embryopteris glutinifera, denominated gaub in the East Indies. It is also rendeied both heavier and less pure, by em- ploying lime too copiously, as a precipitant, which notonly subsides, mixed with the indigo, but also throws down many other useless matters. This also happens in a greater or lesser degree with other precipitants, when used in excess, and more especially with alum. Indigo also differs in regard to its colour, e. g. the guatamala, which has long been the most esteemed of all the varieties of American indigo, is divided into three sorts; of which the first, called by the Spaniards flora, has a very fine blue colour ; the second, which bears the name subre salliente, is violet ; and the third, named corti-color, is copper-coloured. When the first of* these is sold at 9s. the pound, the second is commonly thought to be worth 7s. and the third 5s. <5d. Of the East Indian indigo, that of Java was formerly most esteemed, but since the manufacture of this commodity has so much by which white specks will be formed within the cakes of indigo. See his " Analyse et examen Chemique de l'lndigo, &c." Mem. des scav. etrang. torn. ix. Indigo in drying should always be shaded from the sun, and a free current of air be made to pass over it. PERMANENT COLOURS. 193 engaged the attention of the British inhabitants in that part of the world, indigo superior even to that of Guatamala, has been imported, in considerable quantities, from the British posses- sions there : And of this, the finest blue com- monly sells 20 per cent, higher even than the finest glowing purple, (though the last probably contains nearly as much colouring matter as the first,) and 70 or 80 per cent, higher than the best copper-coloured. The price has, I believe, also, been sometimes affected in this country, by the size and form of the indigo cakes ; the large and square selling for more than those which are flat and thin, and these last for more than broken indigo, though it must all be bro- ken and powdered, before it can be advanta- geously used. M. Berthollet has proposed to ascertain the comparative values of different parcels of indigo, by dissolving equal portions of each in sul- phuric acid, and afterwards destroying their colour by adding the oxymuriatic acid to them, severally, always considering that indigo as most valuable, which requires the greatest por- tion of oxymuriatic acid for the extinction of its colour. But probably the relative quantity, and value of colouring matter, in any parcel of indigo, might be as well measured, or ascer- tained, without employing the oxymuriatic acid, by mixing a certain portion of the 194 PHILOSOPHY OF indigo, when dissolved by sulphuric acid, witlh a certain quantity of "water in a glass, and com- paring the depth, or fullness of its colour, witBi that of other indigo treated in the same way, and taken as a standard or point of comparison. But, after all, there will he so much inequality in the different pieces or cakes of indigo, as it is com- monly assorted, in any one package, that cor - siderable uncertainty must attend any method of ascertaining its true value, by trials witll small parts, or samples only. The most accurate analysis of indigo, with which I am acquainted, is that recently made by M. Chevreuil. He took for this analysis the best Guatamala indigo, and found that by digestion in hot water, it yielded to the latter, ammonia, indigo at the minimum of oxidation* -* What is here called indigo at the minimum of oxidation,, ought to be rather considered as the basis of indigo j for while it is susceptible of dissolution, either by water, or alcohol alone, it does not possess the properties, nor strictly deserve the name of indigo, though capable of acquiring the former, and deserving the latter, by a sufficient addition of oxygene. The existence of this basis or of indigo at the minimum of oxida- tion, in the best Guatamala indigo, proves ths difficulty of thoroughly combining the former, with its full proportion of oxygene by the usual process j and if it be thus contained in Guatamala indigo, how much more of it will have been left iuspended and lost in the beating vat, as commonly managed > M. Berthollet mentions, probably from personal observation, that in Egypt, the indigo making process is so badly conducted, that the indigo produced by it, is always greenish, (" verdatre") and gives a bad colour j jind that it is so much disposed to dig- PERMANENT COLOURS. 19£ combined with ammonia, a particular green matter, in union with ammonia, gum, and a small quantity of yellow extractive matter ; amounting all together to 12 parts for every lOOof the indigo employed. From theremaining SS parts he obtained by digestion with alcohol, 30 partis, consisting of a green matter,a reddish resin, and a little indigo. By digesting the residuum with muriatic acid, he obtained 6 parts of " resine rouge" 2 parts of carbonate of iron, and 2 parts of red oxide of iron, in union with alu- mine, after these had been all separated, there remained about 3 parts of siliceous eartb, and 45 parts of pure indigo. This last, but no other part, was capable, when burning, of emitting that beautiful purple smoke, by which indigo is peculiarly distinguishable ; and which consists of indigo, rendered volatile by heat, without any decomposition. He concluded from this analysis, and from other experiments, that indigo may be purified " par la voie seche, # and par la solve by fermentation, that tbe dyers need only mix a little Irown sugar with it in the vat, to excite one, sufficient to render it fit for dying. An effect which could only result from a deficient oxygenation. See Elements, &c. torn, ii. p. 41. * The pure part of indigo may be ail converted to vapour, without any decomposition, by an elevation of temperature, a little lelow the point at which it would be decomposed, and the simultaneous application to its surface, of a current of any elastic fluid, which exerts no chemical affinity upon the indigo, o 2 196" PHILOSOPHY OF voie humide ;" that when purified, it is suscep- tible of volatilization and crystallization : and that, when most purified, its colour is purple, rather than blue. (See Ann. de Chemie, torn. 6S.) I think it probable, however, that this purple appearance results from a greater conden- sation of the colouring matter of indigo ; since that of Prussian blue, when most pure, exhibits a similar purple coppery aspect. Bergman after separating, as far as he was able, the extraneous matters mixed with indigo, found that 100 parts of it left 47, which he considered as its colouring matter, very nearly in a state of purity; and this being carefully distilled by itself, yielded 2 parts of carbonic acid, 8 of an alkaline liquor, 9 of an empyreu- matic oil, and 23 of charcoal ; which last, being burnt in the open air, left 4 parts, of which about one half was an oxide of iron, and the remainder a fine siliceous powder. Bergman supposed the blue colour of indigo, to result from a combination of iron with the colouring matter of the plant, as the colour of ink does from the union of that metal with the colouring matter of galls, and that of Prus- sian blue from its union with the prussic acid. This, however, will be most advantageously performed, with but small quantities of indigo j for in larger, it will suffer a partial decomposition, if kept for any considerable time, at such a temperature as is necessary to render it volatile. PERMzYNENT COLOURS. 197 But these supposed analogies are without any foundation ; for the proportion of iron is not only by much too small to produce such an effect, but it possesses no affinity for the basis of indigo, nor the least power of influencing, or contributing to its colour. M. de Chaptal, (who as a minister and a che- mist, has manifested a great superiority of intellect, and of science,) appears to think, that in the fermentation of indigo, charcoal greatly contributes to produce its blue colour ; " la dissolution des vegetaux, (says he,) donne un charbon d'un tres beau bleu, et il est probable, qui lorsque la couleur bleu est devellopp£e par la fermentation, le carbone est presque mis a mi, et qu'il reste en combinaison avec unc huile, qui ajoute a la fixite" de la couleur, et indique le dissolvant le plus convenable." (Chim. appl. aux Arts, torn. ii. p. 406.) But if this reasoning were just, why is it that so few vegetables can be made to produce indigo, though all of them contain the basis of char- coal ; and what becomes of the supposed char- coal, when by depriving indigo of its oxygene, in the way which will be hereafter explained, the basis of it, dissolved and secluded from atmospheric air, is rendered colourless, and pel- lucid, until by the re-admission of oxygene, its colour is reproduced ? Certainly there is no instance in which charcoal has been rendered colourless by an abstraction of oxygene, and 198 PHILOSOPHY OF afterwards black, by the re-union of it. Pro- bably, the only similitude between charcoal and indigo, is that which I formerly pointed out ; i. e. that in each, the basis combines with oxygene, and thereby acquires colour and sta- bility; with a complete indissolubility in the former, and a very difficult solubility in the latter. But as their bases are different, so re their respective colours, and several of their other properties. The colouring matter of all sorts of indigo, is nearly the same, and capable of giving nearly similar shades of colour, when the basis has been sufficiently, but not excessively oxygenated. The impure, or extraneous matters, mixed with it [either unavoidably," or fraudulently, are many and various; and they may be generally dissolved or separated, by the means employed by M. Chevreuil ; but when this has been done, there are very few chemical agents, capable of acting upon the residual pure colour- ing matter of indigo, duly constituted. There is, indeed, but one way, in which it can be dis- solved, without injuring its basis, and dimi- nishing the stability of its colouring matter; and this is, not by any single agent, but by the co-operation of several : of these, the first are such as by possessing a greater affinity for oxygene, than that which is exerted by the basis of indigo, are enabled to deoxygenaie the latter, or at least deprive it of a great portion of its PERMANENT COLOURS. 199 oxvgeiie, so as afterwards to render it soluble, by means which otherwise would be incapable of acting upon it ; particularly lime, and the several alkalies, in their caustic state. The matters employed to deprive indigo of its oxygene, and thereby render it soluble, are either vegetable, animal, or mineral. The vegetable are. chiefly such as excite, or promote, fermen- tation; and indigo seems to have been exclu- sively employed with these, for some time after it was first made known, for dying in Europe. Until that period, blue colours had only been dyed oy the woad, as I have already mentioned ; and it being erroneously believed, that the colours of imligo, if employed by itself, would prove fugitive, it was in some countries totally pro- hibited, in others only permitted to be used when mixed with about one hundred times its weight of woad, in what was called the woad- vat. This was, and continued to be, the case in France, even under the enlightened adminis- tration of Colbert, and afterwards until the year 3 737; vvhen, in consequence of the experiments and representations of M. Dufay, a new regula- tion was issued by the French government, per- mitting the dyers to employ indigo either alone, cr with woad, at their option. The preparation of the woad-vat, under the name of Cuve de Pastel, was minutely described by llellot, (Art de la Teinture, chap. 10,) as it has been 200 PHILOSOPHY OF since, more correctly, by Quatremere, Beithol- let, Chaptal, and others; it is, besides, so well known to practical dyers, that a particular account of it from me cannot be wanted by them, and it would be superfluous to my other readers, who need only to be informed, that the woad is brought to ferment by first pouring over it a boiling decoction of weld, madder, and bran, and by keeping it afterwards in a suitable temperature, until blue veins appear on the sur- face of the liquor. Quick lime is then added to St, and also the proper quantity of indigo, finely ground with a small portion of water; the mix- ture is then well stirred, and afterwards covered over ; and such other means arc employed as may be necessary to keep up the proper, and only the proper, degree of warmth and fermen- tation, until a sufficient dcoxygenation, and solu- tion of the indigo, has taken place ; which may be known by the blue or. shining coppery colour of the liquor on its surface, (where the indigo is constantly revived by an absorption of oxy- gene) and by its green tint every where below the surface. With these appearances, the liquor will be fit for dying, and though the colour which it gives to wool or cloth will be green, when first taken out of the dying liquor, it will very speedily become blue, when exposed to the air, by attracting and regaining the oxygene taken from it during the fermenting process; * PERMANENT COLOURS. 201 the abstraction of which was the cause of its green colour. It has hitherto been found extremely difficult to attain the proper, and only the proper, degree of fermentation, in conducting the woad-vat, and this difficulty seems to have resulted prin- cipally from the ever varying properties of the woad, as it has been commonly and ignoraiitly prepared. Indeed, there is good reason to be- lieve, that it would be much better if the manu- facturers of this article would wholly abstain from giving it any sort of fermentation, (which at best is certainly unnecessary) and content them- selves with barely grinding the plant, and dry- ing it as expeditiously as possible, forming it into balls at the proper time. Much also depends upon the quantity of lime employed; not only for the purpose of dissolving the indigo, but also for that of moderating the fermentation ; which, when excessive, induces a putrefactive process, and destroys the tingent power both of the isatis and indigo. Too much lime, on the contrary, obstructs the necessary degree of fer- mentation; the colour of the liquor then becomes blackish, and the vat remajns useless, until the obstacle has been overcome, by the addition of matters, suited to counteract this excess. This vat, or preparation of indigo and woad, is Very generally employed for dying w T ool and woollen cloth or stuffs. 202 PHILOSOPHY OF Indigo is moreover dissolved, without any admixture of woad, in a vat which Heque$ d'Orval et Ribaucourt, Berthollet, and others, have described under the name of Cuve d'lnde* or Indigo-vat ; and which is also well known. For this the indigo being ground with} a little water, its deoxygenation is produced by bran and madder, (acting as vegetable ferments,) and its dissolution by potash. This is liable to fewer failures than the former vat, but it is more costly, and is chiefly employed to dye silk. When fit for use, the surface of the liquor exhi- bits a blue scum, intermixed with patches of a shining coppery colour, and the mass below the surface appears of a line green. The only vat in which animal matters are made to co-operate in the deoxygenation of indigo, is that with urine, now but little used, except as a domestic dye for small woollen articles ; madder, or some other vegetable ferment, is commonly added to assist in abstracting the oxygene, and, when this is done, the ammonia, or volatile alkali, of the urine, produces a dissolution of the indigo. The influence ok' mineral agents in the deoxy- genation of indigo, is yet more obvious and in- teresting than that of animal or vegetable fer- ments; and the former are, therefore, advan- tageously employed by dyers and calico printers, in fixing the colour of indigo upon linen and cotton. Of these the principal is the oxide of 5 PERMANENT COLOURS. 203 iron, at a loxv degree of oxygenation, as it exists in the sulphate of that metal. Dr. Priestley appears to have first noticed the powerful attrac- tion exerted by this sulphate, or by the oxide recently precipitated from a solution of it, upon the oxygene of the atmosphere, though its use, in promoting the dissolution of indigo, had been previously discovered by dyers, but without their having had any suspicion of its mode of action. Indigo moistened, and finely ground, being put into warm water, with twice its weight of sulphate of iron, and the same quantity (as the latter) of pure lime, recently and well burnt, will, with a little stirring, be dissolved in twenty- four hours. In this mixture, a part of the lime unites with the sulphuric acid, forming calcare- ous sulphate, or selenite, and at the same time precipitates the oxide of iron, which, not being saturated with oxygene, attracts so much of that which Mas combined with the indigo, as to render this last soluble by the lime in excess, above that which was required to saturate the sulphuric acid. The beginning dissolution of the indigo, may be perceived by a shining copper-coloured pellicle, which forms itself on the surface of the mixture, while the liquor it- self becomes green, and afterwards gradually inclines more and more to the yellow, as the solution advances. When it is completed, and 204 PHILOSOPHY OF the liquor settled, the cotton yarn or stuffs are to be dyed in it: they appear yellow when first taken out, but by absorbing the oxygen e, will rapidly assume and pass through the different shades of green, and in a few minutes become blue; the oxygene regenerating the indigo, in the pores of the cotton. Mr. Haussman, of Colmar, in Alsace, who, with a considerable stock of chemical know- ledge, daily practises the arts of dying and calico printing, published an excellent " Mc- moire sur flndigo, et ses dissolvans," in the Journal de Physique, &c. for March, 1/88, in which he observes, that the change of colour from yellow to blue, in cottons dyed as before- mentioned, may be greatly accelerated, and the blue rendered deeper and brighter than it would otherwise become, by plunging the dyed cottons, when first taken out of the vat, into water soured by vitriolic acid, which hastens the regenera- tion of the indigo, and moreover dissolves and carries off a portion of white calcareous sulphate, or selenite, which would otherwise diminish the intensity of the blue colour. If the colour of the vat be not all used, soon after it has been prepared, it will require occa- sional stirring ; since the dissolved indigo, by continually absorbing oxygenous gas from the atmosphere, will be constantly revived upon the surface of the liquor; and, when so revived, PERMANENT COLOURS. 205 it can only be re-dissolved, by being again sub- jected to the combined action of lime, and oxide of iron : if by ^length of time these should become perfectly saturated with oxygene, and carbonic acid, before the blue colour is all used, a farther portion of each must be added, and somewhat more of lime than of the sulphate of iron. It must be observed, that where lime is the only solvent of indigo, as in the vat last described, the colour is not sufficiently condensed for dying very deep blues ; and, therefore, when these are wanted, it is found best to increase the power of the lime by an addition of potash, or vegetable alkali, not exceeding in weight twice the weight of the indigo to be dissolved. In calico printing, when different shades of blue are to be produced in the same piece, the indigo finely ground with sulphate of iron, and properly thickened, is first printed on the calico, which after drying, is put alternately into lime water, and then into a solution of sulphate of iron, in different vats, until by these means a sufficient abstraction of oxygene is made by the latter, and a. sufficient dissolution of the indigo by the former, to fix the colour perma- nently. This is called China blue, and M. Chaptal mentions it as an instance in which the colour is applied before the mordant. But it seems to me that there i$ no mordant in this w 20G PHILOSOPHY OF operation which has for its object, nothing but a dissolution of the indigo, which being dissolved, fixes itself by simple application. Mr. Haussman observes, that all the precipi- tates of iron, whether obtained from solutions of that metal by the mineral, vegetable, or animal acids, will serve, with quick lime, to dis- solve indigo, as well as that of green vitriol, provided, and so long as they retain the property of absorbing vital air ; but that a nitric solution of iron, or the rust of it, or any other prepara- tion, where it exists in. an ochrous form, not attracted by the magnet, nor capable of attract- ing pure air, will be wholly useless towards producing a dissolution of indigo, even though employed with an excess of quick lime, or of caustic alkali. Mr. Haussman further observes, that caustic alkali, with fine, iron filings, instead of the pre- cipitate from copperas, would not dissolve indigo ; but that (regulus of) antimony, brought into the form of a powder, dissolved it perfectly with the caustic alkali, or quick lime slacked by water; though the calces, or oxides of anti- mony, in this way, produced no such effe:t : nor did any precipitates of copper: on the con- trary, they all seemed rather to hasten the rege- neration of indigo, after it had been dissolved by some other means. This effect of the oxides of copper, (which results from the great facility PERMANENT COLOURS. 207 with which they relinquish their oxygene) is now well known, and calico printers avail them- selves of it in making what are called reserves, or applications of verdigrese, sulphate of copper, or tobacco-pipe clay, and glue, or in its stead, tallow, mixed and printed upon particular parts, intended to be hindered from imbibing the indigo blue, and kept white, while the rest of the piece is dyed. After mentioning this effect, it can hardly be necessary to add that when the sulphate of iron is wanted to deopygenate indigo, care should be taken that it be not mixed with Any oxide of copper. I have repeated most of Mr. Haussman's experiments, with different precipitates, or oxides of iron, and with effects nearly similar to those he describes. I found that neither the rust of iron, nor the nitric oxide of it, would assist iu the dissolution of indigo; obviously because they were both already saturated with oxygene : I also found, that even the oxide precipitated from sulphat of iron, failed, and for the same rea- son, when, instead of separating it by lime, it was obtained by dissolving the sulphate in water, and leaving it for some weeks exposed to the air in warm weather, where the iron was farther acted upon, and saturated, as well as precipi- tated, by the oxygene which it gained from the atmosphere. It is upon the same principle, that the topical 208 PHILOSOPHY OF indigo blue, employed by calico printers, chiefly with the pencil, is made, only substituting for the sulphate of iron, a portion of red* orpi- ment, (sulfure of arsenic) which has a similar power, when dissolved by an alkali, of depriv- ing indigo of its oxygene, and thus rendering it soluble. The ingredients of this composition are by different persons, mixed m different pro- portions, and will succeed with considerable latitude in this respect; indeed, the variable qualities of indigo, render it difficult to prescribe any exact proportions, which shall be always equally efficacious. Mr. Haussman mixes twenty-five gallons of water, with sixteen pounds of indigo, well ground, (or a greater or smaller quantity, accord- ing to the quality of the indigo, and the depth of colour wanted,) to which he adds thirty * Red orpiment produces a better effect than the yellow, be- cause it contains less oxygene. The fact was known long before the cause. Until lately it was supposed, that the red and yellow differed only by containing different proportions of sulphur j and that this difference enabled one to act more efficaciously than the other, in the deoxygination of indigo j but this is not true. Whenorpimentisemployedinthisway, the alkali precipitates the arsenic in its metallic form, depriving it, at the same time, of a part of its sulphur. After which, the metallic arsenic acts upon the indigo, in the same way as the oxide of iron does, when green vitriol is employed, and by sufficiently abstracting the oxygene of the indigo, enables the caustic alkali to dissolve the latter PERMANENT COLOURS. 209 pounds of good carbonate of pot-ash, placing the whole over a fire; and as soon as the mix- ture begins to boil, he adds, by a little at a time, twelve pounds of quick lime, to render the alkali caustic, by absorbing its carbonic acid. This being done, twelve pounds of redorpiment are also added to the mixture, which is then stirred, and left to boil for some little time, that the indigo may be perfectly dissolved ; which may be known by its giving a yellow colour, immediately upon being applied to a piece of white transparent glass. M. Oberkampf, pro- prietor of the celebrated manufactory at Jouy, near Versailles, uses a third more of indigo ; and others use different proportions, not only of indigo, but of lime, potash, and orpiment; which all seem to answer with nearly equal success; but with the best violet-coloured Gua- tamala indigo, it is certain that a good blue may be obtained from a less quantity than that prescribed by Mr. Haussman, by using as much recently burnt pure lime, as of indigo, the same quantity of orpiment, and twice as much pot- ash. This composition is to be thickened by gum, which should be dissolved in it whilst hot ; and it should afterwards be kept secluded as much as possible from the access of atmos- pheric air. Indigo dissolved in this way, for penciling or printing, I shall hereafter call topical blue — its 210 PHILOSOPHY OF strong tendency to attract oxygene from the atmosphere, and to be thereby regenerated, ren- ders its use subject to many difficulties ; it being almost impossible to pencil, and more so to print therewith, a piece of cotton throughout of the same shade, whatever pains may be taken to apply it equally, and quickly, by the most expert and careful hands.* It will give a fast colour, only so long as it continues yellow, or, at most, of a yellowish green ; as soon as it appears blue, the indigo may be considered as revived, and incapable of fixing itself on the cotton : in this case, however, it may be re- dissolved, by adding more caustic alkali and orpiment. The clear liquor only, when gummed is to be used ; but it is not to be separated from the sediment, which helps to preserve it in a state of dissolution.')' * Being at Manchester in 17Q5, Messrs. Hoyle and Son, shewed me in confidence, a method, of their invention, for print- ing calico, with the topical blue, expeditiously and successfully, by employing cylindrical rollars, and feeding them with the blue, through small perforations made at the bottom of a close receptacle for it, placed immediately over the upper roller, and extending the whole width of the calico, to which the colour was applied before it could have time to absorb oxygene, I believe this invention is now known to others, and that I may therefore mention it without any breach of confidence. f I cannot discover when, or by whom, orpiment was first employed to promote the dissolution of indigo. In some PERMANENT COLOURS. 311 In making the before-mentioned composition, a copper-coloured pellicle appears on the surface of the liquor as soon as the indigo begins to dissolve ; and this pellicle becomes violet, and at last blue, by longer exposure to the atmos- phere. Mr. Haussman observes, that the same pellicle arises, with the same appearances, if the solution of indigo be put into contact with pure vital air; but that, under the receiver of MSS. with the perusal of which I was lately favoured, and which appear to have belonged to the late Dr. Lewis, author of the Philosophical Commerce^ of Arts, and to contain some of the materials employed in that work, I find it noted, in what I consider as the Doctor's hand-writing, and under the date of 1/34, that certain linen printers (calico being then but little employed in that way) had offered to give him one hundred guineas if he could " find out a way to print blue j" and that the writer agreed to attempt the discovery, if these printers would make him acquainted with the best means known to themselves of doing this, which they did, and their composition is stated to have consisted of equal parts of indigo, and quick lime, with half as much copperas, (green vitriol) and twice as much pearl ash. I conclude from this, that the use of orpiment, for the purpose under consideration, was then unknown, at least in this country, though sulphate of iron was employed, but in a proportion by much too small to produce its lest effect. I find afterwards, an account of several experiments made by the writer, to accomplish what was desired of him by the linen printers, but the means employed by him for this purpose, were more likely to impede, than co- operate in the dissolution of indigo. So little was the subject then understood, that all reasoning upon it tended rather to mislead the reasoner, than conduct him to the truth. P 2 212 PHILOSOPHY OF a pneumatic machine, it diminishes in propor- tion as a vacuum is produced; and that, as might be expected, it does not appear at all, in either hydrogcne, or nitrogene. He farther observes, that if, instead of orpiinent, the sulphur and white arsenic, of which it is ^formed, be em- ployed, together or separately, with quick lime and potash, no solution of indigo will take place ; and this will also happen, even where orpiment is used, if quick lime be not employed to render the alkali caustic. That having put indigo, dissolved by orpiment, lime, and potash, into contact with oxygene gas, obtained by distillation from nitre, he soon found that excepting a little nitrogene mixed with it, the whole had been absorbed by the solution of indigo, and the blue rendered unfit for use, the indigo being regenerated. In this instance, he also found that a part of the alkali remained caustic, while another part of it had combined with the vitriolic (sulphuric) acid, (formed by the union of the sulphur to a part of the absorbed oxygene) and thereby produced sulphat of pot- ash ; another part of the oxygene, so absorbed, had combined with the arsenic, and changed its metallic form to that of an oxide, in which state it had united to th6 caustic alkali ; and the rest of the absorbed oxygene had com- bined with, and regenerated the dissolved indigo* PERMANENT COLOURS. 213 Mr. Haussman was indeed inclined to explain the solution of indigo, according to the phlo- gistic system, by considering it as resulting from a greater affinity which phlogiston was supposed to have with indigo than with, arsenic, and that it was the action of this phlogiston, joined to that of the caustic alkali, which ope- rated the dissolution in question ; but that the phlogiston, having still a greater affinity with dephlogisticated (or vital) air than with indigo, abandoned the latter as soon as the former was presented to it, leaving the indigo in its regene- rated form; the alkali alone not being sufficient to preserve it in a state of solution. But a much happier, and more natural explanation of these effects, is afforded by the new doctrine, as already stated ; and it is strongly supported by all that we know of the nature of indigo, and the properties of those agents which are employed to dissolve it. Mr. Haussman found that the sulphuret of antimony (crude antimony) assisted in dissolv- ing the indigo, for topical blue, as well as orpi- ment, but that it was unfit for penciling or printing, because the antimony being precipi- tated, in the form of a mineral kermes or golden sulphur, tarnished the blue colour, and adhered to the linens or cottons almost as strongly as the indigo itself; an inconvenience which I have also experienced. The oxide of antimofty, with sulphur, did not produce a solution of the !U PHILOSOPHY OF indigo, when used instead of the crude anti- mony; though antimony, in its metallic state, (i. e. the regulus) reduced to powder, had occa- sioned the dissolution of indigo in the same way, and as well as the crude antimony. lie found, however, that no such effect was pro- duced by the filings of zinc ; though when heated, this metal has great affinity with oxy- gene. He attempted in vain, to dissolve indigo, by a combination of sulphur with the other metals ; and he attributes his want of success to the circumstance of their being dissolved with difficulty, or perhaps not at all " par la voie humide," in the caustic alkalies. Besides repeating a great part of these expe- riments, and with nearly similar effects, I have made some, which, probably, were not attempted before; and several of them produced effects highly deserving of notice. Having in 1791? attempted unsuccessfully to dissolve pure blue Guatamala indigo, finely powdered, by long and repeated boilings in water, with ai excessive proportion of shell lime taken hot from the fire, and afterwards by renewed boilings with a copious addition of potash, I thought it might be worth while to try the oxide of tin, which had then, I believe, never been employed to promote the dissolu- tion of indigo. It so happened that I had at hand lfcarly a pound of an oxide of tin, pre- PERMANENT COLOURS. 2li pared some time before, (for a different purpose) by putting two pounds of common single aqua fortis, diluted with as much water, upon a quan- tity of tin, not in very small pieces, and leaving the former to act slowly upon the latter during several months, until all its oxygene was exhausted ; after which, I found the oxide, or calx, formed into lumps, and settled at the bot- tom. The clear liquor being decanted from the oxide of tin, the latter was slightly rinced with water, and being dried, remairted in solid lumps. Some of these, weighing about twice as much as the indigo which I had found it impossible to dissolve, by the means just men- tioned, were put into the caustic alkaline liquor, and in less than five minutes I perceived signs of a beginning dissolution, which increased rapidly, until the liquor had passed through all the shades of green, and become yellow, except at its surface, which was covered by a fine cop- per-coloured pellicle, of a shining metallic appearance. Silk and cotton dipped into the liquor, were taken out yellow, but quickly became green, then assumed a shining copper- colour, which afterwards changed to violet, and finally to a deep blue ; which was found, by- washing, to be permanefltly dyed. Part of the same liquor, gummed, and applied topically, answered as well for penciling as any topical blue I ever saw. Another part of it, being 216 PHILOSOPHY OF poured into a white glass phial, so as, with a portion of the lime and oxide of tin, to fill it completely, (without gum) and being well stopped and left at rest, the mixture in a few days became as pellucid and colourless as clean water, excepting only the sediment at bottom.* Upon unstopping the phial, the surface of the liquor, by coming into contact with the atmos- phere, and absorbing oxygene, instantly became first green, and then blue; and upon re-stopping the phial, and shaking it, the indigo forming this blue surface, was dispersed through the mass of liquor, and tinged it of a beautiful greenish yellow ; but there being a sufficient quantity of oxide of tin unsaturated, the oxy- gene was soon absorbed, and the liquor again rendered colourless.^ When, instead of the oxide of tin, I employed * I have/ at p. ] JO, stated the basis cf indigo to be colourless, when wholly deprived of oxygene, and of this, the fact just men- tioned is a sufficient proof. Dr. Roxburgh has indeed said, p. 287* that " the indigo base is naturally green, while it remains dis- solved in its Watery menstruum, by which itwas extracted from the leaves." In regard to this, however, I will only observe, that wherever the basis of indigo exhibits a green colour, it must be combined with a portion of oxygene, and this portion must be greater than that with which it is united in the yellow solution made for giving blue by topical application. f Berthcllet, torn. ii. p. 5J, after mentioning my discovery of the use of the oxide of tin in promoting the dissolution of indigo, adds, " On peut dissoudre immediatement l'etain pea PERMANENT COLOURS. 217 the metal finely granulated, it produced no effect towards dissolving indigo* and on trying tin, which had been calcined with saltpetre in a crucible, I found that it not only did not dis- solve the indigo itself, but prevented it from being dissolved by the oxide of tin (produced by the aqua fortis, as just mentioned,) or by crude antimony, or sulphate of iron, either singly or combined ; indeed it was with difficulty dis- solved, when orpiment, in a large proportion, was added afterwards ; this I also found to be the case of tin, calcined alone in a crucible by stronor heat : bismuth calcined in like manner, equally obstructed the solution of indigo. Pro- bably in these cases the metals so calcined not only did not attract the oxygene of indigo, but let go some of that which they had imbibed during calcination. In the course of my experiments upon indigo, I was induced to make trial of a large propor- tion of refined sugar, (instead of orpiment) and I found that it acted efficaciously in dissolving indigo, with the usual appearances, and produc- ing a topical substantive blue, as permanent, and every way as good as any in use. I afterwards oxide, dans la potasse, et faire agir cette dissolution sur l'indigo : elle produit promptment une cuve ou les toiles se teignent en lieu tres intense." The formation of such a vat was naturally suggested, by the knowledge of what I had published on the subject. 218 PHILOSOPHY OF tried coarse brown sugar, and I found it at least as effectual as the refined, for this purpose; it then occurred to me, that this might be a valu- able substitute for orpiment, the use of which, as a constituent part of the topical blue, may, from its poisonous quality, sometimes produce mischief, and always gives the composition an unpleasant smell. I moreover conceived, that, by employing a large proportion of brown sugar, it might be practicable to thicken the mixture sufficiently for penciling or printing, and there- by avoid the greater ex pence of gum for that purpose; and upon trial, this also proved to be the case, the sugar thickening the solution suf- ficiently, and afterwards drying as expeditiously as when thickened by gum, contrary to what I had apprehended as probable, from recollecting that ink, when thickened by sugar, was disposed to retain moisture, and dry very slowly. I think, moreover, that when the solution of in- digo is both made and thickened by brown sugar, in this large proportion, the latter, by being able to absorb a larger quantity of oxygene from time to time, enables the topical blue to bear expo- sure to the atmosphere somewhat longer, with- out a regeneration of the indigo, than when it is dissolved by only the usual proportion of o-pi- ment. I conclude, therefore, that this way of composing a substantial topical blue, by employ- brown sugar instead of orpin en t and gum, is deserving of particular atten- ing coarse PERMANENT COLOURS. 21& tion, as forming a composition free from all poisonous qualities, and at the same time cheaper and better than that generally used. Molasses will serve as well as brown sugar to promote the dissolution of indigo; but I think, not so well to supply the place of gurn in thickening the composition.* Sugar used in this way, seems to act like orpi- ment in combining with oxygene; which it is strongly disposed to do in other circumstances. M. Berthollet, in the second volume of the An- nates de Chimic, mentions, that, in distilling the * Since the former edition of this volume, I find that, according to Professor Pallas, the blue dyers of Astra can dis- solve indigo, by boiling it in a lixivium of soda, with quick lime and clarified honey ; which last appears to act like sugar in the deoxygenation of indigo. Dried raisins and figs, I have observed to produce a similar effect. Probably the most useful and inoffensive topical blue may be made by boiling powdered indigo with three times itsweight of coarse brown sugar, inacaus- tic lixivium of soda and potash, and assisting the deoxygenation by adding the oxide of tin precipitated by lime from a solution of that metal by muriatic acid. ]f a muriate of tin be added to the topical blue, prepared with caustic alkali and redorpiment, or with caustic alkali and sugar, it will occasion a considerable effervescence, and at the same time produce a farther deoxyge- nation of the indigo, and thereby render the previous greenish yellow colour of the mixture almost white, and make the effervescing froth appear almost of the colour of milk, though even this froth, if speedily applied to calico, will attach itself, and by regaining oxygene, stain it with a permanent blue colour. Such an effervescence, however, is inconvenient, and I only mention the fact as an additional illustration of the theory before stated. 220 PHILOSOPHY OF sulphuric acid upon different animal and vegc- table substances, lie found none of them so proper as sugar to form a large quantity of sul- phureous acid; which it could only produce by its great affinity withoxygene. I found, upon different trials, that, with the help of potash and lime, I could not dissolve indigo, either by sulphur, or white arsenic, or charcoal, or oxide of bismuth, or of lead (mi- nium) or of zinc (lapis calaminaris,) or of man- ganese, or the alkaline solution of flints, or of the earth of alum, or by magnesia. I was equally unsuccessful with copper, in all the ordinary preparations of it : and indeed when verdigrise was added to indigo mixed with lime and potash as usual,— -there was not only no solution, but the verdigrise afterwards obstructed the action of all other agents upon it, insomuch that the indigo remained undissolved, notwithstanding the com- bined action of crude antimony, orpiment, oxide of tin, sulphate of iron,and sugar, which were added in large doses, any one of which, with the quick lime and potash, would have effectually dissolved the indigo, bad there been no verdigrise or oxide of copper in contact with it. The sulphate of zinc (white vitriol) was almost as adverse to the dissolution of indigo; for it not only did not contribute thereto, with potash and lime, but* it hindered a solution from taking place, by the exide of tin, crude antimony, sugar, and sul- PERMANENT COLOURS. 221 phate of iron, applied one after the other : though when to all these, a large portion of orpiment was added, and the mixture kept some time in a boiling heat, the indigo did at length dissolve, but with great difficulty and tardiness. The red sulphuret of mercury I found, on re- peated trials, incapable of contributing, in any degree, to dissolve indigo with lime and potash; thou arh it did not obstruct the dissolution there- o of, when orpiment was added. Wishing to know what effects would result from a stronger action of potash, lime, and or- piment upon indigo, I dissolved it with three times the usual portion of these agents, and having afterwards shaken the whole mixture well toge- ther, I filled a large transparent glass phial there- with (but without any gum,) and having secured it from all contact with external air, by a glass stopper covered with wax, I left it in that state for three months, shaking the phial occasionally, that the more fluid part of the mixture (which had become colourless) might be acted upon more equally by the lime, &c. at bottom; after which, the phial being opened, I found that the mixture (which with different proportions, had always given a deep permanent blue to cot- ton,) was become incapable of manifesting any colour by the contact of atmospheric air ; tlie indigo having been not only deprived of the -oxy gene necessary to its colour, but probably oov PHILOSOPHY OF rendered incapable of re-uniting with it as for- merly, in consequence of a decomposition of its vegetable basis, or a new combination thereof, with one or more of the agents in question, too intimate to be overcome by any of the usual means of regenerating indigo. Here we have an instance of one of the most permanent ©f colouring matters losing its colour irrecoverably ; not by any thing like combustion, which neces- sarily requires the presence and combination of vital air, but by means which seclude it from, and deprive it of, all such air. The topical blue, when made, is often applied by flie pencil upon spots or figures previously dyed yellow, in order to produce a permanent green : but the caustic alkali contained in it, especially when employed too freely, seems to weaken the yellow on which it is laid. Wishing to remove this difficulty, I thought of neutraliz- ing the alkali, at least in some degree, so as to make it harmless in this respect, without, at the same time, rendering the blue less efficacious. For this purpose I selected the muriatic acid pricci- . pally, because as no oxygene had ever been as- certained to exist, as one of its constituent prin- ciples, there seemed to be no danger of its re- reviving the indigo, by imparting oxygene to the topical blue when mixed with it : and having made this mixture, the effect answered my ex- pectation; for though it produced some effei- 2 PERMANENT COLOURS. 225 vescence, it neither rendered the mixture blue nor even its effervescing surface, though covered with froth; but both remained green, while secluded from the contact of atmospheric air, by being inclosed in a vessel well stopped ; and I found it practicable in this way to neutralize the alkali completely, without rendering the indigo unfit to produce a fast blue colour, or a green, when applied to yellows, if applied quickly; but when the topical blue, thus neutralized, had been kept some time, the indigo, being deprived of the alkali which had held it in solu- tion, gradually subsided in a great degree, and became unfit to be applied topically. There is, however, I think, an intermediate degree to which the alkali may be neutralized, without precipitating the indigo, in any considerable quantity, at least for several weeks, and which will be sufficient to prevent the alkali from exercising any action injurious to the yellow colours upon which the blue may be laid. The fluoric acid employed in this way an- swered as well as the muriatic ; and I now find this to be true of the sulphuric and some other acids ; there being no danger, as from some former in- accurate experiments I had once supposed, of a revival of the indigo, by mixing either of them with the topical blue, the attraction of the basis of indigo, (in this preparation) for oxygene not being sufficient to decompose any of these acids, 224 PHILOSOPHY OF so far as I know. Carbonic acid is always pre- sent in the topical blue without being decom- posed; and no injury is produced by other acids when mixed with it, so long as,, by not being decomposed, they are incapable of reviving the indigo. I have ascertained also that the oxy- genated muriatic acid will not revive it: a fact which I once thought favourable to the opinion of Schecle and Davy, that it contains no oxy- gene ; but the other facts just stated, shew that nothing decisive in that respect can be inferred from it. It is to be observed, that all the preceding means of rendering indigo soluble, by abstract- ing a part of its oxygene, serve only to bring it back to the state in which it existed while dis- solved, and retaining its green colour in the fer- menting process, before its minutest particles had been collected together, in a concrete blue form, by agitation ; and I have already mentioned, at p. 171, my persuasion, that the colouring matter of the indigo plant, in this fluid state, is not only fit for dying, but that the blue colour dyed with it, would, like that of the isatis, or woad, prove more permanent than that given by the indigo, after it has been made to assume a concrete form ; be- cause its basis, even by the least hurtful ways of dissolving it, will, I think, necessarily be in some degree weakened, as all other vegetable colours are found to be, by the action of such powerful agents as are requisite for that purpose; PERMANENT COLOURS. 2$ and I think it probable, that the very durable blues which are given by particular people in some parts of Africa, owe their superiority to this method of dying. According to Mr.Clarkson, " it is well known, at least in the manufacturing towns, that the African dyes are superior to those of any other part of the globe." " The blue (continues he) is so much more beautiful and permanent than that which is extracted from the same plant in other parts, that many have been led to doubt whether the African cloths brought into this country were dyed with indigo or not. They apprehended that the colours in these, which be- came more beautiful upon washing, must have proceeded from another weed, or have been an extraction from some of the woods which are celebrated for dying there. The matter, how- ever, has been clearly ascertained: a gentleman, procured two or three of the balls, which had been just prepared by the Africans for use : he brought them home, and upon examination found them to be the leaves of indigo rolled up in a very simple state. Sulphate of Indigo. The powerful action of sulphuric acid upon indigo, and the very bright lively blue colour thereby produced, had been observed by che- mists long ago, but no person seems t© have 226 PHILOSOPHY OF applied this colour upon cloth as a dye, until about the year 1740, when it was done hy Coun- sellor Earth, at Grossenhayn, in Saxony. In addition to the indigo and sulphuric acid, he employed crude antimony and lapis caliminaris, (and as some say alum) mixing them with the oil of vitriol first, and adding the indigo after- wards : but these additions being found useless, were after some time discontinued. Whew a bit of pure flora, or blue Guatamala indigo is dropped into concentrated colourless oil of vitriol, in a flint glass phial, radiations of a bright greenish yellow may be seen almost immediately projecting from the indigo, and resulting from a solution begun upon its surface ; and if the phial be left unagitatcd, these radia- tions soon become green, and afterwards blue, without any motion or change in their direc- tion. This sudden conversion of the blue colour of the indigo, to a greenish yellow, seemed to indicate an abstraction of oxygene, as its cause-; but it was difficult to conceive how such an ab- straction could result from the application of an acid, already completely saturated with oxy- gene. I recollected, however, that Berthollet had mentioned, as one of the effects caused by the action of sulphuric acid upon indigo, that, of its determining (as it does with sugar) the pro- duction of a little water, in consequence of the intimate combination which it etlects between PERMANENT COLOURS, 227 certain portions of the oxygene and hydrogene, which are among the constituent parts of in- digo; a combination by which he accounts for the great heat, resulting from a mixture of pow- dered indigo with sulphuric acid, and the non production of sulphureous acid thereby. This fact, of the production of water by a combination of a part of the oxygene of the indigo, with a part of its hydrogene, enables us to understand how the indigo may, and, indeed, must be deprived of a portion of oxygene, sufficient to change its colour, suddenly, to a greenish yellow ; and this change being effected, the progress after- wards, to green and blue, accords with the series of changes observed in the topical blue of the calico printers, after its application; and in- dicates a restitution of the oxygene, taken from the indigo by the formation of water. To ascertain with certainty whence this restitution was made, or rather whether any part of it. was derived from the atmosphere, I placed a small piece of the blue Guatamala indigo in a phial, and filling it completely with colourless oil of vitriol, I closed it immediately with its ground glass stopper, which came in contact with the acid and indigo, (the latter from its levity rising to the top) so as to leave no space for air. I then placed the phial at the window, and keeping it wiotionless, saw, by transmitted light, streaks of 228 PHILOSOPHY OF greenish yellow radiating downward from the indigo, and gradually changing and passing through all the intermediate shades of green, to a full sky blue ; and as nothing could have been gained from the atmosphere during these changes, it wds manifest that they must have been pro- duced by something contained in the sulphuric acid ; and as the latter does not appear in this operation to suffer any decomposition, nor the indigo to be capable of effecting any, I conclude, that when this last has been rendered soluble, by the deoxygenation resulting from a production of water, it enters into a triple combination with the oxygene and sulphur composing the acid, and thereby regains its blue colour, with addi- tional brightness; either from its union with an increased proportion of oxygene, or from some effect resulting from the sulphur, which had not been combined with it originally. But though the colour is rendered much more beautiful by this triple combination, it is accompanied with a great diminution of its for- mer stability, and differs essentially from the so- lutions of indigo made by lime and alkalies, assisted by the deoxygenatingagents lately men- tioned; for when indigo is revived or recovered after the latter mode of solution, it is found to possess all the properties which belonged to it before.it had undergone any solution, including its original indissolubility, (except by the agents PERMANENT COLOURS. 229 already mentioned.) But after being dissolved by sulphuric acid, it can never be revived with its original and peculiar properties. It may, indeed, be readily precipitated by alkalies, but excepting a blue colour, the precipitate will differ from indigo, in every respect. It will no longer retain the power of emitting its cha- racteristic purple smoke, when ignited ; and it may be readily dissolved, by all the acids, and alkalies, as well as by other agents which pre- viously had no dissolving power over it; and, though most of these solutions are blue, their colour has but little permanency, especially those made with pure alkalies, whether fixed or volatile, as they soon spontaneously become green, and finally colourless. When the basis of indigo, after being sufficiently deoxygenated, is dissolved by lime or alkalies, it forms no permanent combina- tion with either, and may afterwards be separa- ted and recovered from them without hav- ing suffered any perceptible injury or change. But the effect is very different after this basis has been dissolved by any of the acids ; probably it suffers least injury from the sulphuric, though with this, indigo can hardly be said to produce a fast colour, even on wool, since, as Haussman observes, it is easily extracted by soap in boiling water, and changed bv alkalies to an olive colour, more or less yellow, according as the alkali is more or less caustic; and since the 230 PHILOSOPHY OF adhesion of this blue to linen and cotton is so feeble, that cold running water will gradually cany it off. Bergman, (whose labours have thrown much light on the subject of indigo) ascribes the want of greater permanency in the Saxon blue, to the use of sulphuric acid, not sufficiently concen- trated. He used an acid whose specific gravity, compared to that of water, was as 1900 to 1000, and employed eight pounds of this acid, to dis- solve one pound of indigo. I believe, however, that he was misled on this subject, and that Pcerner is much nearer the truth, when he says, that the best proportion for dissolving indigo, is only four times its weight of good pure oil of vitriol; and that where more is used, the blue is less permanent. I am even inclined to think that the blue will prove more durable, if this last quantity of acid be diluted, with an equal portion of hot water, as soon as the indigo is put to it, and the mixture left in a warm situation, 48 instead of 24 hours, for the indigo to dissolve: because, bv a slower, and more moderate action, I think the basis of the indigo will be less weakened ; at least I have frequently dissolved indigo in this way, and the colour has appeared to be more durable, than when it was dissolved by an undiluted acid.* * If the indigo be finely powdered, it will be thereby ren- PERMANENT COLOURS. 231 The indigo being dissolved, Mr. Pcerner adds as many ounces of dried potash, as there were of indigo in the solution, which produces an effervescence ; and after twenty-four hours, he. adds eight pounds and a half of water, for each pound of oil of vitrol employed, and puts the whole into a glass vessel for use.* Instead of potash, I have used clean chalk, and this even in such quantities, as to saturate the vitriolic acid. The indigo was then precipitated with the chalk, and being collected in a solid mass, it was still capable of dying a blue on wool, though it took much more slowly, than in the ordinary way of dying Saxon blue; in which the colour applies itself so rapidly to wool or woollen cloth, as to render it difficult to prevent its taking unequally, a defect which might pro- bably be obviated by a small portion of chalk. It is to prevent this inequality, that M. d'Am- bourney advises, where deep Saxon blues are wanted, to pass the cloth at different times through vessels containing only what might dered soluble, with a smaller proportion of the acid, and even that proportion may be more diluted. * Poerner says, and I think truly, that by this addition of potash, a more agreeable blue is produced, and that it penetrates farther into the cloth. He mentions as an instance of the abun- dance of colouring matter afforded by indigo, his having dyed five pieces of cloth, each weighing one pound, of different shades of Saxon blue, all with a single half ounce of indigo. 232 PHILOSOPHY OF suffice for weak colours, in order that the blue may, by these partial applications, be made to take with more evenness. Silk, dyed along with wool, takes a much weaker colour, (I mean with the addition of chalk) because it has less affinity with the indigo, than wool has. This prepara- tion of indigo, however, would not give a deep blue, because being united with so large a por- tion of white sulphate of lime, the blue colour- ing particles could not be sufficiently condensed for that purpose. Poerner conceives the Saxon blue to be rendered more durable by previously preparing the cloth with alum, and sulphate of lime. The solution of indigo by sulphuric acid, is Usually called by dyers chemical blue. It ought, however, according to the new nomen- clature, to be termed sulphate of indigo; a name by which I shall continue to distinguish it.* When applied to wool, the blue colour is much more permanent than it is in a fluid state; for though a little manganese, added to * Pcer.ier describes a sulphate of indigo, which be prepared in a dry solid form, and reserved as a secret : he represents it as being more commodious, and advantageous for dying, than the common sulphuric solution of indigo. Berthollet conjec- tures (torn. ii. p. 97) tnat this may have been the precipitate which I had recommended, of sulphate of indigo, by an addition of carbonate of lime. It doubtless must have been a precipitate by this or other means. PERMANENT COLOURS. 23S the sulphate of indigo, instantly destroys its colour,* wool, which had been previously dyed blue with some of the same preparation, was not discoloured by the action of manganese, dissolved in sulphuric acid. I do not know that a black was ever produced Dy the sulphate of indigo, or by any other pre- paration of that drug alone. Mr. John Wilson, who greatly contributed to improve the art of dying at Manchester, has asserted, that though a redundance of colouring* matter, will increase the force and body of a colour, yet that no repeated dyings of blue will become black. I have, however, now before me, two pieces of cloth, one of which is the deepest and purest black perhaps ever seen, and it was dyed by me, very lately, from sulphate of indigo, em- * The destructive action which manganese exerts upon the colour of indigo, when it (i. e. the manganese) is mixed with sulphuric acid, though weaker, resembles that of muriatic acid, after it has been mixed with manganese ; and to my concep- tion, affords a strong presumption, that in both mixtures, the destroy i ng power depends upon a co-operation of some ihinggained from the manganese ; which is, however, contrary to the notion of Scheele and Davy, that muriatic acid, by its admixture with manganese, and conversion to oxymurialic acid, gains nothing, but is merely deprived of the hydrogene previously combined with it ; and that this deprivation constitutes the whole diffe- rence between the muriatic and oxymuriatic acids. Manga- nese added to the topical blue, soon revives the indigo, but does not injure its colour, 234 PHILOSOPHY OF ployed alone, though in an unusual quantity ; the other is a line Saxon blue, which was cut off from the first, before it had taken up so much of the blue colour, as to become black. I lately- found also, in making the topical blue, that a small piece of cotton, which I had thrown into^ the mixture, and which, being forgotten, had remained there forty-eight hours, was, when taken out, of z full black, so permanently fixed, that neither lemon juice nor alkalies seemed capable of impairing it. I could not, in one or two trials afterwards, succeed in producing a similar black on linen or cotton; and it must be remarked, that when I produced this, it was in a mixture to which I had at first put a little manganese, to see whether it would promote the dissolution of indigo; and find- in£ it did not, I had afterwards added more than the usual proportion of orpiment ; one or both of which additions, may have contributed to the black in question.* * That Saxon blo.e^ or the colour of indigo, in combination with sulphuric acid, depends upon the union of a certain pro- portion of oxygene, as in all other preparations of this drug, may be proved, by adding to the sulphate of indigo, a little muriate of tin, which, by its ordinary deoxidating influence soon changes the blue, first to green, and then to a pure bright yellow. If this yellow mixture be applied to linen or calico, it will dry without losing its yellow colour, the affinities of the oxide of tin, ox of the muriatic acid, or of PERMANENT COLOURS. 235 The sulphuric acid, or oil of vitriol, as com- monly prepared, contains a small portion of the nitric, which, however small, necessarily does some harm in forming the sulphate of indigo, M. Captal observes, that he has seen the colour fail, and the stuffs intended to have been dyed, spoiled by this fault in the sulphuric acid employed for that purpose, which ought, there- fore, to be guarded against as much as possible. The indigo of all others most preferred for Saxon blues, is the flora of Guatamala, which indeed is seldom employed for any other species of blue. The other kinds, when mixed with oil of vitriol, effervesce sometimes very strongly, in both, counterbalancing that of the indigo for oxygene. But if the linen or calico be moistened with a weak solution of carbonate of soda, or potash, to neutralize the acid, the yellow will return through all the shades of green, to the former Saxon blue. Muriatic acid without tin, produces no change in the colour of sulphate of indigo, because it has alone no deoxyge- riating power. Analagous to the preceding fact, (now first men- tionad) is that published by Vauquelin, cf the deoxygenating in- fluenceof hydro-sulphurated water, which when mixed in a close stopped phial with sulphate of indigo, soon becomes green, and jn a few days yellow ; but if the phial be afterwards unstopped the sulphate of indigo gradually returns through the different shades of green, to its former blue colour, as fast as the sepa- ration of sulphuretted hydrogene permits the indigo to recover its oxygene. An undissolved hydro-sulphuret will act more efficaciously in this way, so as to render the sulphate of indigo almost colourless ; after which, if it be applied to calico, the Jatter will first become yellow, next green, and then blue. fS6 PHILOSOPHY OF consequence of the extrication of fixed air; the presence of which, may easily be accounted for, by recollecting that lime is commonly employed to accelerate the separation and pre- cipitation of the minute particles of indigo* while in the vessels called beaters, and that in doing this, it subsides with the indigo, after having absorbed carbonic acid, which in this way is again set free by the oil of vitriol. Here it will be proper that I should offer some conjectures on the cause of the different colours of indigo: and as a foundation for these, I must remark, that the flora, or blue indigo of Guatamala, is much lighter than the violet, and that this last is lighter than the copper- coloured. From the lightness of this blue indigo, and from its not effervescing with acids, when dissolved by oil of vitriol, there is the strongest reason to conclude that no lime is employed to accelerate the separation and precipitation of its colouring matter in the beaters ; since, if there had been any, it would have increased the specific gravity of the indigo, and by absorbing carbonic acid, would necessarily have caused an effervescence, when dissolved in sulphuric acid; assuming, therefore, that no lime is employed to separate and precipitate the colouring matter, it would necessarily follow, that, to obtain such separation and precipitation, the agitation must have been continued longer than would other- PERMANENT COLOURS. 23? wise have been necessary, and the unavoidable consequence would have been, the combination of a larger proportion of oxygene, with the colouring particles so exposed to it, than that which takes place with those separated by lime : it will therefore follow, that indigo, obtained in this way, will contain a greater portion of oxy- gene than in the other ; and it seems natural to conclude, that the blue colour is occasioned thereby. To ascertain, however, the justice of this conclusion as far as I was able, I took some of the lightest and bluest Guatamala indigo, and dissolved it by lime, potash, and orpiment, as usual ; one effect of such solution, we know to be, the taking away from the indigo a con- siderable part, at least, of its oxygene ; and I accordingly found, as I have done in all cases where indigo was dissolved for the topical blue, that the dissolution was accompanied with a bright shining copper-coloured pellicle upon the surface of the liquor, which of itself was of a greenish yellow underneath. The production of this pellicle may be easily explained by recol- lecting that the dissolved indigo, which lias lost its oxygene, and become thereby of this greenish yellow, being at its surface in immediate con- tact with atmospheric air, regains a part of what it had lost, and by doing so, becomes copper- coloured ; but swimming as it does upon a mixture disposed to attract oxygene, it cannot, S3 8 PHILOSOPHY OF in this state, retain so much thereof as the indigo itself formerly had, while it was of a blue colour; and therefore, so long as the body of the liquor remains yellow or green, the pellicle covering it, will be only copper-coloured, though consisting of a colouring matter which was formerly blue, and which would have become so again, if, being dissolved, it had been thinly applied to linen or cotton, and brought suffi- ciently into contact. with the oxygene of the atmosphere. As therefore this blue indigo had apparently become copper-coloured, only by having less oxygene than before, is there not from this circumstance, an additional reason to conclude, that the copper-coloured indigo, sepa- rated and precipitated by lime, is made of that colour, only by its possessing a smaller propor- tion of oxygene than the blue indigo ? and whilst this blue indigo is preferred for combina- tion with sulphuric acid, as producing least effervescence, we should expect that the copper- coloured, as being the least oxyginated, would be most suitable for the indigo vats, and for the topical blue, because in these the dissolution is effected, by taking away oxygene ; and the less there is of it, the more easily will this be effected ; and here the choice and practice of the dyers accord with my hypothesis, as they constantly employ the copper-coloured indigo for these last purposes. PERMANENT COLOUR3. 23!) Having already noticed all the known means or solvents by which indigo can be rendered useful in dying, I will only add a few observa- tions concerning the effects of some other agents upon it. If strong nitric acid be mixed with powder- ing indigo, its action upon the hydrogene of the latter will be so violent, as to produce actual combustion ; and when diluted, its power, though moderated, will always prove destruc- tive of all the useful properties of indigo, unless it be made so weak, as to manifest no sort of influence upon it. When it is of the strength of common or single aqua fortis, ifc dissipates a considerable portion of the com- ponent parts of the indigo, and converts the remainder into a rusty brown viscous bitter mass, which will burn and detonate, and which, according to Haussman, is soluble in alcohol, and also in water, when the proportion of the latter is very large. With a more diluted nitric acid, the indigo at first affords a bright yellow, but it soon changes to the rusty brown before mentioned ; and the basis of indigo is then so completely decomposed, that the blue colour cannot be restored, by any of the various means which I have employed for that purpose. The most concentrated muriatic acid, even with a boiling heat, has no action upon the pure colouring matter of indigo, though it dis- 2 1AQ PHILOSOPHY OF ' solves some other parts of it; and this is true of the citric, tartaric, acetic, phosphoric, fluoric, and other acids. A mixture of sulphuric, nitric, and muriatic acids, greatly diluted, will slowly dissolve pow- dered indigo, and change its colour to a very bright lively yellow, which appears to have con- siderable stability, though it could not be fixed on linen or cotton. It is remarkable that though the strongest muriatic acid, even when boiling, has no influ- ence upon the colouring matter of indigo, yet this, or even a much weaker acid, when it has been saturated by dissolving tin, will, if mixed with powdered indigo, in the common tempera- ture of the atmosphere, speedily make it green, and afterwards yellow ; holding a considerable portion of it suspended in the state of a yellow solution, whilst the residue subsides, as a pow- der of the same colour. In this case, the oxide of tin first produces a deoxigination of the basis of indigo, and thereby renders it soluble by the muriatic acid, to which it was before inaccessible. But being so dissolved, this basis either undergoes a decomposition, or enters into a new combination with the oxide of tin, or the muriaticacid, or both, of a nature so intimate, that no means which I have been able to employ, to remove or neutralize the acid, have enabled the indigo to regain its former portion of oxygene, or PERMANENT COLOURS. ♦41 return to its former blue colour; as the sul- phate of indigo will do by such means, when it has been made yellow by muriate of tin. The insolubility which the basis of indigo acquires by combining with oxygene, may, as Berthollet observes, be compared to that of certain metallic oxides, which at a maximum of oxidation, cannot be dissolved by acids, but are made soluble by the application of means suited to produce an abstraction of oxygene. And here I may terminate my explanation of the extraordinary and highly interesting che- mical properties of indigo, believing that it will suffice to enable my readers to understand, both the reason and effects of the several methods and means employed to fix its colour, by dying and calico printing. It now only remains for me to mention some facts respecting the history of indigo, which have been purposely kept back, because I believed they would be read with more interest, and be better understood when the properties of this drug had been previously made known. Mr. J. N. Bischoff, in a work which mani- fests great reading on the subject of dying, ("Ver- suche einer geschichte der Farberkunst, 1780,") appears to think, that the indigo with which we are acquainted, was unknown to the Greeks and Romans ; that the indicum of Pliny was not a dying drug, but a paint very different from R 242 PHILOSOPHY OF our indigo ; and that the charter or contract which passed in 1194, between the cities of Bologna and Ferrara, respecting certain duties to be paid at the former city, upon the Grana de Brasile, (or Kermes) and upon indigo, alluded to the indicum of Pliny, and not to the substance now called indigo. It may, however, be demon- strated from the known properties of our indigo, and those which Pliny has distinctly mentioned as belonging to his indicum, that the former is an exact resemblance of the latter. After de- scribing the preparation of a very costly fine purple substance employed by painters, (and obtained by skimming the vessels in which the Tyrian purple was dyed,) Pliny mentions, (lib. xxxv. c 6.) the indicum as next in value and importance. " Ab hoc maxima autoritas indico: ex India venit," &c. — " cum tcritur nigrum ; at in diluendo misturam purpura? eseruleique mira- bilem reddit." - After this mention of the coun- try whence it was obtained, and of the admira- ble mixture of blue and purple colours which it exhibited by being diluted, he adds, that it had been frequently adulterated by pigeons' dung, and other fradulent mixtures; and then, with great sagacity, he points out a trial by which the genuine drug might always, and certainly, be distinguished jrom the spurious; and this was by putting it upon live coals; where, says he, the true indicum will burn with a Jlame of the PERMANENT COLOURS. 248 most beautiful purple tint. " Probatur carbone : redd it enim, quod sincerum flammam excellentis purpura." I have already at p. 195, mentioned this purple flame, and the purple smoke accom* panyiqg it, as peculiarly distinguishing indigo. It was a criterion abundantly sufficient for Pliny's purpose, and the only one, which, in the then deplorable state of chemical science, could have been suggested by him. It is true that the Greeks and Romans, not knowing how to dis- solve indigo, used it only in painting, but their ignorance did not alter its nature, or hinder it from being, as it must have been, the identical substance, with the uses and properties of which, we are now so much better acquainted. It is true, also, that Pliny was mistaken, not in regard to the place whence it came, but in regard to the way in which it was produced ; he having supposed it to be a slime naturally collected in the scum of the sea, and adhering to certain reeds growing on its shores (" harundinum spu- ma3 adhcerescente limo"). And with this notion, he imagined that the peculiar odour of indigo, when burning, resembled the smell of the ocean, a circumstance which he says made some think it was gathered from the rocks (" dum fumat, odorem maris olet : ob id quidam e scopulis id colligi putant.") These notions, and the diffe- rent names and circumstances, which w T ere applied to this substance, or mentioned as con- R 2 U4 PHILOSOPHY OF nected with it, by Dioscorides, Galen, Paulus .flEgineta, and others, induced Caneparius, in his work " de Atramentis, &c." (p. 193) to adopt what he supposed to have been the opinion of the former, that two different colouring matters from India were known to the ancients, one naturally adhering to reeds, &c. as described by Pliny, but now, as he supposed, wholly unknown to the moderns ; and the other, an artificial sub- stance similar to our indigo, and which he sup- posed to have been extracted from the isatis, or woad, by boiling it in dying vessels, and collect- ing and drying the scum, or skimmings, (as Pliny had mentioned to be done to obtain a pigment by the dyers of Tyrian purple.) This he adds, is called in vulgar language, " Endego" and is brought by merchants from India to Alexan- dria, in iEgypt, and to Syria, and thence im- ported to this city of Venice, now become (say* he) the emporium of the whole world.* * " Consequitur ergo ut," — " duo atramenti Indici genere fucrent a Dioscorirle constituta.. (unum) eorura prodidit natu- rale quod sponte ab arundinibus in India paludibus, instar spumsc vi solis exiens humor concrescebat colore purpureo, quo tamen prorsus caremus. Alterum vero Indici genus scriptum nobis reliquit esse arte factum j dum enim in cortinis, haec sunt vasa inf'ftctorum in quibus tingunt pannos, ebullit glastum isatisve herba dicatur, et vulgo guado, tunc efflorescit, innatatque spumma purpurea, quam seduli artifices detrahunt, etsiccant." This, he adds, is " quod vulgus appellat Endego, corrupto tocs- PERMANENT COLOURS. 245 This work of Caneparius, was printed in 15 19, at Venice, (where he lived, and where dying was then more practised, and better under- stood, than in any other part of Europe :) and I adduce his testimony chiefly to correct an error into which M. Berthollet appears to have fMlen, when (at p. 22, of the first volume of his Elements, &c.) he asserts, that the first indigo made use of in Europe, was imported from the East Indies by the Dutch* The fact is, that for a considerable time before the first voyages of the Dutch, to the East Indies were made, indigo, in considerable quantities, had been imported through Egypt and Syria, to Italy, and employed in dying. That this was one of the uses of that which Caneparius mentioned, as being imported through those countries from India, is evident from his next page (194), bulo j boc a mercatoribus defertur ex India, Alexandriam JEgypti, et in Assyriam, demum ex illis partibus in hanc Venetiarum Civitatem universi mundi Emporium advehitur" That Caneparius was not accurately informed of the plant which afforded indigo, or of the method in which it was obtained, will surprize no one who is told that, according to Mr. Ray, botanists, even when he wrote in 1 688, were not agreed on this subject, though the plant was suspected to be a legumi- nous shrub, belonging, or allied to the genus Colutea. * " II parait meme que le premier, (indigo) qui ait ete employe en Europe, nous a ete apporte des Indes orientalei par les Hollandais." 24S PHILOSOPHY OF where, after noticing the fact, of its having been formerly employed as a medicine, he adds, that in his own time, it was used by the dyers and writers; that the former were accustomed to dissolve it in vats, with a lye of wood ashes, and other wares, according to their own prac- tices, concerning which, says he, it is not my office to give instruction.* Caneparius was a physician, and not likely to have been minutely informed in regard to these practices ; and yet, in the same page, he describes very accurately, the method of preparing, for dyer's use, the isatis, from which he believed the indigo to have been extracted,! and from which indigo may indeed be obtained. I find among my papers, a statement, which * " Usus igitur Indici est hodierno tempore tinctoribus , et scriptoribus : nam dissolvunt eum tinctores in Caleariis cum lixivio, et aliis more suo, hsec tamen vos docere non est meum institutum." f " Isatis est herba, quje ante floremcolligitur, et sub mola tunditur, et facto ex ipsa cumulo maceratur soil, mox in magnos globos redacta, et sub tecto locata aspergitur aqua, ut magis, potiusque, maceretur tunc edit magnum fetorem, et nigrescit, et sic prseparatio Isatis sive glasti dicatur idem est, perficitur ad tincturas," p. 194. The supposition of Caneparius, that indigo was obtained from the isatis, or woad plant, seems to have been prevalent even in this country, so late as 1640, when Parkinson, who was then treating of indigo, called it " Indico, or Indian Woada." PERMANENT COLOURS. 247 Lmade some years ago, on the authority of Sir Plans Sloane, (and taken, as I believe, from his Natural History of Jamaica, &c.) importing, that the annual consumption of indigo in Europe, about the year 1620, (soon after the time when Caneparius wrote) amounted to 350,0001b; and that this came principally by the way of Aleppo, where it was computed to cost 4s. 6Y1. the pound. It is probable, there- fore, that the Dutch had not then begun to import indigo, by the Cape of Good Hope ; or at most, that they imported but very little of it. That it had previously, for a considerable num- ber of years, been imported through or from Turkey, is evident from several facts, and among others, from Mr. Hackluyt's " remembrances for Master S ," who, in 1.582, was going to Turkey, and, among other things, was instructed " to know, if anile, that coloureth blue, be a natural commodity of those parts, and if it be composed of an herb?" See Voyages, ii. p. lGl. Ed. 1599- Bischoff has, however, furnished decisive evi- dence to prove that the use of indigo in Europe, as a dye, was anterior to the first voyage made by the Dutch to the East Indies. He tells us, (Versuche, &c.) that the appellation or distinction of woad dyers, amongthe Germans, may be found in a charter, dated so early as the year 1339 — that with these, certain Flemish and Italian 248 PHILOSOPHY OF dyers, who had resorted to Germany, were after- wards incorporated under the name of Art.Woad, and Fine Dyers : that they excited the jealousy and enmity, of a more ancient corporation, the black dyers ; and as Indigo was employed by the former, the black dyers, influenced by this en- mity, exerted themselves with so much success, in decrying this dying drug, that the Elector of Saxony, and Duke Ernst the pious, issued severe prohibitions against the use of it; and that even in the Diet of the Empire, it was described as a pernicious eating devil, and corroding dye stuff. " Fressende Teufels," &c. and for these prohibitions of the Elector of Saxony, he refers to the Codex Augusteus, part 1, p. 236, under the dates of 15121 and 1547 ; and in regard to the opprobrious appellations applied to indigo in the Diet of the empire, he refers to a work printed at Frankfort, in 1577; all which dates are much earlier than any of the voyages of the Dutch to the East Indies. In what way Indigo was first dissolved, or used for dying in Europe, I know not ; but in the old collection of recipes, which I have mentioned in the introductory part of this volume, as trans- lated from the Dutch, and printed in London, so early as 1605* I find one at p. 32, respecting the use of indigo, which is there called flora, or "Jloray"* and directed to be fermented by the • In the act of the 23d year of Queen Elizabeth, cap. ix, in- PERMANENT COLOURS. 249 'vat process, with wood ashes, bran, and greening weed, (probably weld) and the appearances indi- cating the fitness of the fermenting liquor, to be digo is designated by the names of " ancle, alias Hue inde." — How long the vulgar Italian name of "endigo," mentioned by Caneparius, had prevailed in that part of Europe, I am not able to ascertain ; but it appears to have been afterwards adopted and spelt with exactly the same letters, in the account of Canche's voyage to Madagascar, and by other French writers of that time j and our name of indigo has manifestly been thence derived.— The Spaniards and Portuguese, who had found the way to India, by two opposite courses, at a much earlier period, and there be- came acquainted with this production, adopted the Hindu name of anil, and aneileira ; and these are the nations by whom in- digo was first manufactured in America, viz. by the Portuguese in Brazil, and by the Spaniards in Mexico, where they each recognized the plant growing spontaneously. It seems extraor- dinary, therefore, that professor Thomas Martyn should have erred, as he has done, in his recent edition of Miller's Gardener's Dictionary, by representing "nil or anil" as "the American name" of indigo, and concluding, that the Portuguese had bor- rowed their name from the Americans, not from the people of India. — Though the French and English were later than the Spaniards and Portuguese, in encouraging the manufacture of in- digo in America, they afterwards made considerable progress in it. The former exported from the island of St. Domingo only, in 1774, 2,350,000lbs. weight of this commodity, and nearly about the same time in 1773* in the space of twelve months, 1,107,000 pounds weight of it, were exported from South Ca- rolina. But in both places, the manufacture of this commo- dity has ceased, from new, though different circumstances. The deficiencies, however, which might have resulted from these changes, have been fully obviated by an increasing production of indigo in the East Indies, The importation and gale of this com- 250 PHILOSOPHY OF applied to the stuffs to be dyed, are distinctly pointed out ; especially that of its becoming green. How early this had been known, or how long- this collection of recipes had existed in Dutch, or any other language, previous to the English impression in 1605, I cannot say; hut there is, I believe, no reason to think that the Dutch had even then began to import indigo. That this artificial production was first obtained from India, is proved by the testimony of Pliny, and other ancient writers, confirmed by a variety of circumstances; and particularly by its name, which is known, from numerous authorities, to have been nil in the Hindu language, from the earliest times, in which there is any authentic mention of it : and this name still continues to be modity, at the East India bouse, in 17Q2, amounted only to 58l,827lbs. whilst the importation into Great Britain, from ether parts of the world, amounted to 1,285, 927IDS. since which :ime the latter importation has gradually declined to Jess thana fcurth of the former amount j whilst the importation from the East Indies, and sales at the India house in the year 1806, amointed to J, 81 1 ,700lbs. and produced in sterling money 1,685,275/ and the importation and sale at the India house, in the folloving year, amounted to 5,153,9661bs. and produced the sure of 1,863,091/. sterling. — I have no accurate account of the sales of East Indian indigo since 1807. They may probably iave diminished a little within the last year or two, because the ob- structions co the exportation, resulting from the peculiar circum- stances of the existing war, have considerably reduced the jrice of this commodity ; the importance of which, as a dying crug, greatly exceeds that of any other. PERMANENT COLOURS. 251 given by the Hindoos, to all the plants whence Indigo is obtained by them; not excepting the nerium tinctorium, from which Dr. Roxburgh believed that no indigo had ever been ob- tained until his discovery respecting it. The late Sir Wm. Jones has however stated in the fourth volume of Asiatic Researches, that a Hin- doo peasant, who brought this shrub to him, gave it the name of nil, which signifies blue in the language of that country. "A proof," adds he, " that its quality was known to them, as it proba- bly was to their ancestors, from time immemo- rial." — When the Arabs and Egyptians after- wards obtained a knowledge of indigo, and of its use, (as they did of many other things) from India, they naturally adopted the name, with the substance itself; the Arabs calling it nil and nir, as Julius Scaligcr long since mentioned, (in his book, on plants,) and the Egyptians giving it the name of nil, or neel. It is stated in the memoirs of the Baron de Tott,(p. 2/8,) that the seeds of the in- digofera tinctoria, with which the Egyptians dye their only garment (a linen shirt) are imported annually from Syria; Egypt being a hot-house which exhausts the plant, before the seeds can ripen. The Egyptians, therefore, were not likely to be the first discoverers of a manufacture, de- pending on a plant, which could not yield pro- lific seed in their own country. Concerning the history of theisatis, or woad, 252 PHILOSOPHY OF I shall make but a very few observations. It was called by the former name among the Greeks, and particularly by Dioscorides ; but it bore that ofglastum among the Gauls and Germans ; which, in their language, signified glass : hence C.assar, in the 5th chapter of his 5th book, de Bello Gallico, says "omnes vero se Brittani vi- tro inficiunt, quod cseruleum efficit colorem : at- que hoc horribiliore sunt in pugnae aspectu." — Pliny distinguishes it sometimes by the Greek, and at other times' by the Gallic names; and in the first chapter of his 22d book, he mentions it as resembling the plantain, and as being called glastum by the Gauls ; and though he does not repeat Caesar's observation, that the Britons made their skins blue with it, in order to appear more terrible in battle, he says, that their wives and daughters painted their bodies with it, when they appeared naked, at the sacred festivals, so as to resemble Ethiopians. He had previously men- tioned, in the 7th chapter of the xxthbook, that this plant was employed to dye wool. But though the Britons in Caesar's time ap- pear to have cultivated enough of the woad to dye their skins, the inhabitants of this island at a later period, obtained it from abroad, to dye their garments ; and, indeed, they are said to have depended wholly on the French for it, until 1576. But in 1582, Hackluyt remarked, that it was then brought to good perfection, (in this kingdom) PERMANENT COLOURS. 253 to the great loss of the French, our old enemies." (See Voyages, &c. vol. ii. p. \6\. ed. 1599.) I do not find that the woad plant lias ever been ob- served to give a blue colour to the milk of cows, like the indigo, which, when eaten by them, not only renders their urine blue, but, according to Dr. Garden, of South Carolina, the cream of their milk also became "of a most beautiful blue co- lour." See Phil. Trans, vol. 1. p. 296. Gardenia Genipa. The Genipa Americana of Lin. has recently been united to the genus named Gardenia, by the late John Ellis, Esq. in honour of Dr. Gar- den, formerly of South Carolina. Swartz, on whose authortiy this change was principally made, has strangely represented this, as being only a shrub, though I have frequently seen the tree growing 50 or 60 feet high, with a trunk five or six feet in circumference. Its fruit, (the only part connected with this sub- ject,) is technically denominated a berried drupe, nearly of the size and shape of a lemon, a little pointed, and umbilicated at the end, and covered by a skin, which, whilst unripe, is of a light ash colour, with a slight appearance of green : immediately under the skin, is a white solid fleshy substance, moderately sucu- lent, about one third of an inch in thickness, surrounding a soft pulpy matter, of an oval '254 PHILOSOPHY OF form, and about an inch in diameter, consisting of two cells, in which many flattened roundish seeds are nestled in rows. If this fruit or berry, whilst unripe, be sliced or broken, and exposed to atmopheric air, its colourless substance, or the clear juice expressed from it ; almost immediately acquires a strong deep blue colour, and is universally employed by the savage tribes of Guiana and Brazil, to stain their skins with a variety of spots, lines, and figures, for the purpose of ornament at their feasts and dances, as well as to render themselves terrible to their enemies when going to war ; as the isatis, or woad, was employed by the Britons in Caesar's time. But the most sin- gular circumstance attending this application is, that no repetition of washing with soap, nor any other application, so far as I could learn at the several times of my being in Guiana, appeared to have the smallest power to remove the blue stains so produced, until after some days, (gene- rally nine or ten ;) when the epidermis, or scarf skin, by perspiration, rubbing, &c. appears to wear away, and make room for another, which is un tinged ; aud it is in this way only t as I believe, that the stains in question sponta- neously, and gradually disappear, after some days.* * Since my last return from Guiana, I find it stated by Hart- PERMANENT COLOURS. 255 Oviedo seems first to have mentioned this tree by the name of xagua; but he describes the colour produced by its unripe fruit, as being black, adding that the stain given by it to the skin, cannot be removed in less than 10 or 12 days ; and that it never can be effaced from the finger nails, until by their growth or elongation the stained parts can be removed. Francis Ximenes afterwards mentioned the tree by the name xahuali, which it bore in New Spain, he says, the stain is only to be removed from the skin after fifteen days, and never from the nails, except by their growth and separation, as explained by Oviedo. Marcgrave, (Brazil, p. 90,) described the tree under the names of janipaba, and janipapa, by which the Brazilians called it, and from which the more prevalent name of genipa, was derived. He says, " immaturus fructus concisus, et cuti affricatus, tingit colore ex nigro sub casrulescenti, qui nulla modo ablui potest, sed post octo aut nona dies spoute evanescit." Piso (at p. 138,) asserts, that the stain spon- taneously disappears, not only from the skin, but from paper in about nine days, (tinctuia sinck, (" Besehryving van Guiana/' i. 49,) that the acrid milky juice of the fruit of the carica papaya, or papau tree, will re- move the stains in question j which, if true, is a curious fact, and I regret not having been informed of it, whilst I had proper means to ascertain the truth experimentally. 256 PHILOSOPHY OF enim illius corpori, vel charta illita circa nonam diem evanescit.") An assertion which has been often repeated, and generally believed, though it never had any better foundation, than a pre- sumption, that because it did not remain on the skin, it would not remain upon paper ; and hence it was concluded, that dangerous frauds might be practised, by writing with this colour instead of ink, Coppier had, indeed, made this assertion some years before, (" Historic et Voyages des Indes occidentales," printed at Lyons, 1645, p. 91,) And he pretended that the fact had been first discovered by himself, and that he had endeavoured to consign it to obli- vion for the prevention of fraud. There was, however, no foundation for this pretension. I have now before me, both parchment and paper, on which I wrote with the juice of the unripe fruit of the tree under consideration, seven years ago, and it has not, as far as I can discover, suffered the smallest decay ; and there is good reason to believe it would prove even more durable than the common writing ink, though it differs from it, by inclining much more to the dark blue colour. The J'abk, how- ever, of the fugitive nature of this ink, and the dangerous purposes to which it might be ap- plied, was so generally and firmly believed, by the inhabitants of the Essequebo and Demerary, that I was induced to report it as credible in '2 PERMANENT COLOURS. 257 the volume, which, at an early age, I published respecting the Natural History of Guiana, in 1760.* This tree, like the nerium tinctorium, asclepias tingens, &c. belongs to the natural order of Contort a, and is known at Essequebo, Deme- rary, and Befbice, by the Arrowauk name of launa, and of Surinam by that of tapouripa, which undoubtedly was borrowed from some of the neighbouring tribes, probably the Carribees, with whom the first (English) settlers in that colony, had more communication than with any other ; though I cannot find this name in * Francis Ximenes mentions that tricks were sometimes practised with the juice of this fruit, by privately mixing it with rose water, and giving it to the ladies in New Spain j and Dutertre, in his Account of the French West India islands, writing of this tree says, " il porte le fard des charabrieres nouvellement venues." He adds that the simple maid servants, who, in considerable numbers, about that time, came to the West Indies from France, were told upon their arrival, that unless they washed their hands and faces with the (colourless) juice of this fruit, their skins would become Hack, and that, believing this, they eagerly collected and applied the supposed means of preserving their complexions, and were astonished, soon after the application, to find their faces and hands covered with a hideous dark blue stain, which nothing could remove for nine or ten days. He indeed mentions his having married considerable numbers of them, before this stain had been removed, and repeats the fable respecting the supposed frauds which might be practised by using the juice of this fruit as a substitute for ink. £58 PHILOSOPHY OF any vocabulary of the language of that people- Mad. Merian, has mentioned this tree inaccu- rately, under the name of tabrouba, and has intended to represent a branch of it, at her 43d cllate, but has transposed the explanation, or description belonging to this plate, by joining it to her 48th plate, and connecting to the former, that which relates to the latter ; a blunder which no person seems to have before noticed. "When this volume was first published in 1794, I believed, and stated my belief, that the blue colour of the fruit in question, like that of indigo, resulted from a combination of oxy- gene, with a vegetable basis ; and in fact that it was similar to indigo. And this belief was principally founded upon my having, when at Surinam, 1770, applied the colourless juice of the fruit, to pieces of linen and calico, and seen the parts to which it was applied, speedily become blue, as happens with the indigo and woad plants; and upon my having found that the colour so produced was not discharged by repeated washings with soap, nor consi- derably injured by exposure to the sun and air for several days : my experiments at that time were, however, but few in number, and made under the disadvantage of being then but little acquainted with the subject of dying : wishing, therefore, for greater certainty respecting the nature and properties of this colouring matter, PERMANENT COLOURS. 259 t determined, when I visited Guiana a third time, in 1805, if possihle, fully to investigate the subject. And accordingly having observed, soon after my arrival in Demerary, a young gar- denia getiipa tree growing on the plantation Rein- stecn, then belonging to Messrs. Brummell and Addison, which tree, though probably bearing for the first time, exhibited two or three dozens of the berries or fruit, each about the size of a nutmeg. I informed Mr. Brummell of my wish to make experiments with them at the proper time, and with his usual kindness, he imme- diately ordered that they should be all carefully preserved for my use. In a few weeks after, I observed the tree to have shed all its leaves, (as happens to trees of this species at certain sea- sons,) and that it afforded the uncommon spec- tacle of a leafless tree bearing fruit. About this time, circumstances connected with the state of mv health, determined me to return immediately to Europe, by the way of Barbadoes; and having no leisure to make even a single experiment, the fruit of this tree, which had thenalmost attained its full growth, they were all gathered, and embarked with my baggage. But finding soon after my arrival at Barbadoes, that they were becoming soft, and in danger of spoiling, before I could conveniently make the experiments which t intended, I caused them to be sliced and dried in the sun ; presuming that s 2 260 PHILOSOPHY OF * they might afterwards be preserved several years, like the indigo plant, in a state fit for my experiments. But while this was doing, the sudden transition of the whole inner colourless substance of the sliced fruit, to a full dark blue, without any intermediate yellow or green tint, engaged my attention, as indicating an impor- tant difference between this, and the basis of indigo ; for it was hardly credible that the affi- nity for oxygene, should be so much greater in the former than in the latter, as to enable it at once to become blue, without even the momen- tary appearance of an intervening green. By the part which I took in slicing this fruit, my fingers were deeply stained ; and as this stain might well seem indecorous to the gen- tlemen and ladies, with whose hospitalities I was daily honoured, I spared no pains to remove it, by repeated washings with soap, alkalies, &c. and by frequent applications of lemon, and lime juice, but without producing any sensible dimi- nution of this troublesome dark blue colour, until it disappeared in the usual way, by an apparent abrasion of the cuticle. 1 did not neglect, when in Barbadoes, to apply some of the juice of the sliced fruit, by which my fingers were stained, to pieces of calico, impregnated with alumine, and the oxide of iron, as well as to some wliich had no impreg- nation, and I afterwards found that neither of PERMANENT COLOURS. 2GI these bases had any affinity for the colouring matter under consideration; it being in no re- spect changed thereby. The calico without any basis, had acquired a very dark blue tinge, which was not altered by washing with soap; nor by exposure to sun and air for some days; though in this respect it seemed to be less per- manent, than I had believed it to be, from my former experiments in Surinam. Since my return to London, I have made such trials as to me appeared suitable, with the sliced and dried fruit of the gardenia genipa, which, though more than seven years have elapsed, still retains a dark blue colour ; but this manifestly depends on principles very dif- ferent from those of indigo. For it is soluble both in potash and soda alone ; and when lime and orpiment were added to these, no change of colour ensued (from blue to green,) indicating a susceptibility of deoxidation. Sulphuric acid seemed to brighten the blue colour as it does that of indigo. But (unlike sulphate of indigo,) this mixture appeared to have no affinity for vegetable substances, and so little for the animal, that cloth by long boiling in the blue liquor, would only receive a slight drab colour. Nor does the juice of the fruit seem capable of permanently staining the fingers, after it has already become blfe. The addition, whatever it be, which occasions the blue, if made bej'orc 262 PHILOSOPHY OF it touches the skin, rendering it incapable after* wards, of attaching itself either to animal or vegetable substances. Nitric acid changes the blue to yellow, as it does that of indigo. Several writers have asserted, that the fruit of the gardenia gen i pa when ripe, becomes yellow, and loses its disposition to assume a blue colour. Whether this colourable property was in any degree affected, by my having kept the fruit in question, until it was approaching towards rottenness, (which might produce effects like those of ripeness) I know not ; but as its blue colour evidently results from causes, dif- fering greatly from those which produce the colour of indigo, it seems very desirable to ascertain their nature ; though I think this can only be done by trials upon the unripe and re. cent ly gathered berries, which, while their juice remains colourless, might be placed, some in vacuo, others in the several gasses separately, and exposed to the sun's rays, as well as kept in obscurity, to discover which of these situations and agents contributed most, either to hasten or retard the production of the blue under con- sideration. Brown, in his History of Jamaica, p. 143, observes, that " the pulp of the berries of the Randia aculeata, Linn, (called in that island the indigo berry, and which grows plentifully on the smaller branches of the plant,) is very thick, PERMANENT COLOURS. 263 and stains paper or linen of a fine fixed blue colour. I have tried it (continues lie) on many occasions, and have always observed it to stand, though washed with cither soap or acids; but it does not communicate so fine a colour with heat. It would prove (he adds) an excellent fixed blue in all manner of paints and prints, if it could be obtained in any quantity ; but the berry is not very succulent, and the people as yet are not very industrious in these parts." This plant, like the genipa, has recently been added to the genus gardenia, (under the name of gardenia aculeata,) and it is remarkable that their generic characters being similar, their fruit also should yield blue colouring matters, which, as far as I know, seem to resemble each other. The indigo berry, in like manner, belongs to the natural order of contortce, which more than any other, contains plants yielding the blue colour. Mr. Martin Lister (in the Vlth Vol. of the Philosophical Transactions, page Q13Q,) men- tions that " the seed husks of glastum sylvestre, old gathered and dry, being diluted with water, stain a blue, which, upon the affusion of lye, strikes a green, which green or blue, being touched with the oil of vitriol, dyes a purple; and all these colours (sa^s he) stand." Some of the mushrooms alaO becomes blue, when exposed to atmospheric air. The same effect, according 261 PHILOSOPHY OF to Sennebier, happens to the milky juice of the tithymalus euphorbia, Lin. It is mentioned somewhere in the Swedish Memoirs, by Cronstcri, that the stalks of the polygonum fagopyrum, Linn, by fermentation in water, afford a blue which did not change either by acids or alkalies. Green Indigo. About the year 1790, Mr. Alderman Prinsep, who had then lately returned from India, gave me a specimen of indigo obtained there, as he informed me, from a tree, (which I then sus- pected to be the panitsjica-maram, of the hortus malabaricus, though I now suppose it- must have been produced from the nerium tinc- torium, lately mentioned ;) and he, at the same time, gave me a very small piece of a hard green substance, likewise produced in the East Indies, and which he called green indigo. Upon seeing it, I flattered myself with a hope of its proving to be what the late Mons. de Poivre had mentioned in a little work, published under the title of " Voyages d'un Philosophe," &c. as obtained by the inhabitants of Cochin- china from a plant called tsai, which, when macerated and fermented like indigo, yields a green fecula, capable of dying a fine, as well as a lasting emerald, or green colour.* The quan- * Loureiro mentions, (torn. i. p. 25, of the original Lisbon PERMANENT COLOURS. 2G5 tity of this green substance so put into my hands, was much too small even for a single decisive experiment. I however divided it into three parts. One of these I put into boiling water, which appeared to have no action upon it ; but it was afterwards dissolved by a little oil of vitriol, like common indigo, producing, however, a green, instead of a blue colour. A second of these parts I dissolved with a little caustic alkali and orpiment, in order to see whe- ther, excepting the difference of colour, it would possess properties similar to those of indigo, when dissolved by the same means, and like the latter be able to produce a fixed colour on linen or cotton by topical application. This, however, it did not seem to be capable of doing : the re- maining part I put into a little spirit of wine, which dissolved a portion of it, though very slowly ; a circumstance in which it differs ma- terially from indigo, and seems in some degree to resemble that green-coloured fecula which some plants afford, and particularly the cruci- form, when fermented like the indigo plant in warm weather. I confess, however, that these edition,) the justicia tinctoria, as growing wild in Cochin- china, adding '* folia viridi colore saturata, eodem telas pulchre imbuunt." Whether the plant, whose leaves alone are here represented as capable of producing a green dye, has amy relation to the tsai of M. de Poivre, 1 know not. PHILOSOPHY OF experiments were made on such very small quantities of the substance under consideration, that very little dependence ought to be placed upon them, But this is certain, that if a simple or homogeneous green colouring matter exists, and can be discovered, with properties in other respects similar to those of indigo, it will be a most important addition to the Materia Tine- tor ia. Barasat Verie. In the year 1793, Messrs. John and Francis Baring, and Co. received from R. C. Birch, Esq. of Calcutta, parcels of two new drugs, in- tended for dying ; samples of which were put into my hands, with a request that I would make suitable trials of their merits; and with a paper containing some explanations which had accompanied them from India. One of these (and the only one which I shall notice at this time) was called Barasat Vcrte, and was formed into dry hard cakes, resembling in size and shape those of the indigo sent from Bengal ; but of a dark dull green colour. It was stated to be a simple substance, and to have been pre- pared with water and fire only, " from an indigo- ferous plant, an ever-green, witli leaves some- what resembling those of the laurel, bearing large clusters of small yellow flowers, and pro- ducing seed in large pods, pointed at the end, 5 PERMANENT COLOURS. 267 and it was added, that the seed did lt not vegetate in Bengal." It was also represented as giving- a durable light green colour, without any mor- dant or basis, to silk and wool ; and to be inca- pable of dying dark green without the aid or addition of some blue colouring matter. To bring this green indigo into a state fit for use, it was directed to be finely levigated with sand, and then boiling hot water was to be poured upon the powder in a suitable vessel ; and being left to settle, the water " tinged with a dirty brown colour was to be poured off;" and these washings were to be repeated until the water came from the powder colourless ; and then to the remaining powder, an equal quantity of fixed vegetable alkali, obtained by calcining salt-petre upon burning charcoal, was directed to be added, with a proportionate quantity of water, and the mixture made to boil for two or three hours ; after which, it was to be left " to digest for two days at least." In this prepara- tion, diluted with boiling water, the silk or woollen stuff was directed to be dipped for the space of half an hour, and then washed with soap in water; a longer dipping was represented as giving no greater body or depth of colour. After what has been just mentioned on the subject of green indigo, it will naturally be concluded, that my curiosity must have been greatly excited by that now under eonside- m m?A 268 PHILOSOPHY OF ration ; and indeed I lost not a single minute in making such a trial of it, as would decisively ascertain whether it really possessed the proper- ties of indigo, with only the difference of a green instead of a blue colour. This was by powdering and boiling it in water with a suita- ble portion of lime, pot-ash, and red orpiment, as is practised in making the printer's blue for penciling; (see page 113, &c.) and in doing this, I soon perceived, with great satisfaction, that the mixture exhibited exactly the same smell, and the same appearances, as those which arise in making the printer's blue ; the surface of the liquor was covered with a fine shining copper-coloured scum, and beneath this, when separated, the liquor itself exhibited a lively green. Being impatient to see how far its effects were similar to those of indigo dissolved in this way, I applied some of the green liquor as expeditiously as possible, by the pencil, to a bit of calico, and soon perceived that it con- sisted of two very dissimilar colouring matters; one, which proved to be true indigo, was im- mediately revived by an absorption of oxygene, (as happens to the printer's blue when so ap- plied,) whilst another part of the liquor spread itself farther, and retained a kind of olive green colour, which the air did not change. The calico, after being dried, was washed with soap, and that part of the liquor w r hich had PERMANENT COLOURS. 2G9 spread farthest, and retained the olive green colour, was soon wholly washed out, leaving behind the pure indigo, adhering to the spots and strokes where it had been applied. Having thus convinced myself that this substance con- tained a portion of true indigo, I powdered an ounce of it, and mixed the powder with six times its weight of sulphuric acid, as in making the sulphate of indigo for Saxon blue : in about twenty-four hours the powder appeared to be nearly all dissolved, and the solution was of a blue colour, with a greenish tinge : and by put- ting a little of it into warm water, and dying a small piece of flannel therein, a full Saxon blue was soon produced ; though the colour had a greenish cast, occasioned manifestly by the same olive-coloured matter which I have just mentioned as having shewed itself upon the calico.* I afterwards tried the method recommended by the author of this discovery, of separating the yellowish brown colouring matter from the powdered green indigo, by repeated ablutions with hot water, and then employing a pure * A small bit of the Barasat Verte being ignited, it burnt with a brisk red flame, emitting fumes, of which a considerable part exhibited the fine purple tint, peculiar to those of indigo. It left a residuum, equal to about half its bulk, of a dark choco- late colour, of which carbone seemed to constitute a consider- able part, but this I did not particularly examine. 5 270 PHILOSOPHY OF caustic vegetable alkali to dissolve the residuum. In this way I obtained a solution which, upon wool, dyed a light olive or apple green ; I found, howeven as I had foreseen, that none of the true indigo had been dissolved, either by these last trials, or those made in Bengal, it being impossi- ble, as I have formerly explained, to dissolve indigo by caustic alkali alone; and indeed the discoverer of this preparation, in the account which he transmitted from Bengal, candidly acknowledges that he had never been able to dissolve the sup- posed green indigo " entirely, a considerable quantity having always remained precipitated at the bottom of the vessel." And this insoluble residuum, (which appears to have been lost, or at best to have remained wholly useless in all the experiments made in Bengal) I found by further trials to be true indigo. For by separating the solution made by caustic vegetable alkali from the residuum, then pouring upon the latter farther portions of caustic alkali in hot water, until the lixivium came away colourless ; and afterwards submitting what remained to the action of muriatic acid, to dissolve any hetero- geneous matters which the alkaline menstruum had left behind, I at length obtained a consider- able quantity of indigo, of a middling quality; part of which, being dissolved by sulphuric acid, dyed wool of a good Saxon blue colour, with- out any of the greenish tinge which had attend- PERMANENT COLOURS. 271 ed my first trials; and another part being dis- solved by pot-ash, lime, and red orpi merit, as for the printer's topical blue, produced the usual ef- fects of indigo in this way. Having applied the acetite of alumine topically to a piece of cotton, as is practised in calico-printing, and dyed one part of it in the yellowish brown coloured liquor, which had been obtained by pouring hot water on the supposed green indigo in powder, and another part in the olive green liquor, obtained from the same powder by Caustic vegetable alkali, I found that, though each imbibed a dirTerent colour, neither was fixed upon the figures which had been printed with the aluminous basis, or on the parts to which no mordant or basis had been applied, and that the colours were removed by washing with equal facility from every part : a certain proof that the yellowish brown and olive green colouring matters were not of the adjective kind, (having no affinity with the aluminous basis,) and that they are not likely to be of any use in dying ; for though they should prove lasting upon woollens, there are many other and much cheaper means already in use for giving colours of this kind to wool. It seems evident, there- fore, that the true nature of the supposed green indigo was but very little known to the dis- coverer thereof ; and that its useless heterogene- ous parts were the only ones which produced 272 PHILOSOPHY OF the colours dyed in Bengal, and which induced him to send it to Europe as a dying drug. Whether the supposed green indigo owcb its production to an insufficient combination of oxygene ; or, in other words, whether the mat- ters which dyed the yellowish brown, and the olive green colours, before mentioned, are simi- lar to that which forms the basis of true indigo, and capable of being converted thereto by a longer fermentation, agitation, &c. ; or whether they are of a nature essentially different from the basis of indigo, though naturally combined with it in the particular plant whence the sub- stance under consideration is extracted, are important questions which I am unable to an- swer. I have indeed mixed the supposed green indigo, in powder, with water, and kept the mixture for several days at a degree of warmth suited to promote a fermentation, but without being able in this way to render its colour blue, or increase the proportion of true indigo which it had before contained : but perhaps I might have been more successful with a greater quan- tit}', or a larger fermentible mass, than what I was able to employ in this way. I have had reason to conclude, that the sup- posed green indigo, either from a redundance of colouring matter in the plant from which it was extracted, or from some other cause, may be obtained at much less expence than the true PERMANENT COLOURS* 275 indigo ; and if this be the case, it must doubt- less prove a very important discovery, if the yellowish brown and olive green matters are capable of being changed to indigo, by a farther combination of oxygene :| and even if this should not be the case, perhaps theawsonia spinosa (alhenna,) is so ancient in Egypt, that he hat PERMANENT COLOURS. 23S t lately received a few ounces of small seeds, inclosed in a flea-coloured husk, but without any information respecting the plant on which they grew. They were brought from the coast of Barbary, where, as I was informed, they are used in dying red or pink colours. In two or three small trials which I made with them on silk, they appeared to possess a substantive colouring matter, similar in some respects to that of saf- flower. At first I thought they might be the seeds of the gardenia florida, which, according to the accounts of Mr. James Cunningham, who formerly travelled into different parts of the East Indies in pursuit of natural curiosities, the Chi- nese employ for dying scarlet, under the name of wild* I found, however, that this could not be the case, as the seeds of the gardenia grow in- closed, several of them in one common capsule, involved in a rich-coloured mucilaginous sub- seen the nails of mummies dyed therewith. He adds, that th« powdered leaves are annually exported in great quantities. Lourerio says, of the Lawsonia spinosa, " foliis contritis ad- mixta calce, utuntur Cochinchinenses, ad tingendos ungues co- lore ruberrimo : qui mos pro elegantia invaluit non solum apud alios populos Indianos, sed etiam apud Turcas, Persas, yEthyo- pes." Tom. i. p. 229. * Dr. Plunkenet, in his Amaltheum, page 29, says, " Semina tinctoribus inserviunt us enim ab indigenis Sinensibus optime tingitur nobilis ille color, quern escarlatinum nostrates vocant, ut nos monuit vir multiplicis industrise atque indefessi laboris hac in parte, D. Jacobus Cunninghamus." 286 PHILOSOPHY OF stance ; whereas the Barbary seeds evidently grew without any such inclosure. I cannot dis- cover whether the seeds of this gardenia, or the mucilage surrounding them, ought to be consi- dered as a substantive or an adjective colouring substance; all accounts being defective in this respect.* Sajjlower. This is the Carthamus tinctorius, Linn, which is cultivated in the southern parts of Europe, Egypt, &c. and aLo in the East Indies, whence * When the late Sir George Stanton returned from the em- bassy to China, in which he was associated with Lord Macartney, he gave me some yards of a cotton cloth, which had been dyed scarlet, and probably from the gardenia florida, (now called cape jasmine in this country.) It was one of the articles mentioned by Mr. Barrow in the following words, viz, " among some of our presents were also pieces of a beautiful scarlet." (P. 5(30.) The colour of the cloth so given to me, certainly approached nearer to the cochineal scarlet, than any which I have seen dyed on cotton, in Europe, and it seemed to be of a resinous nature, dyed substantively without any basis, and capable of bearing ex- posure for a reasonable time to the sun and air, but liable to be in a considerable degree discharged by washing with soap. Con- centrated oil of vitriol had but little effect upon this scarlet. — Strong muriatic acid changed it to an orange j and double aqua- fortis made it yellow. So that it was much less injured by these acids, than colours vastly more durable are known to be. Loureiro moreover mentions another species of this genus, viz. gardenia grandiflora,whose succulent berries, recently gathered, are, as he says, (torn. i. p. 147..) employed to dye silk of an ele- gant red colour. PERMANENT COLOURS. 2S7 considerable quantities of it have been lately imported to Great Britain. There arc two varie- ties of this plant, one of which is distinguished by having much broader leaves than the other. Berthollet mentions the narrow-leaved as that which is cultivated in Egypt, whence consider- able quantities of it are from time to time ex- ported.* It is the flower only of this plant which is employed in dying, and which affords two sorts of colouring matter, one soluble in water, and producing a yellow of but little beauty, when dyed adjectively, on an aluminous basis; the other is resinous, and best dissolved by the fixed alkalies : it is this last which alone renders saffiower valuable in dying, as it affords a red colour, exceeding in delicacy and beauty, as it does in costliness, any which can be obtained, even from cochineal, though much inferior to the latter in durability. To obtain this red colour of saffiower, it should be tied up in a linen bag, and subjected to maceration and pressing in clean running water, until all the yellow colouring matter is dissolved, and washed away, and the flowers which were previously yellow, are made red by an abstraction of this yellow colour. This being done, the flowers are ao-aiii to be macerated in a solution of clean * Niebuhr says, there are 10 varieties of saffiower cultivated in Egypt, and that the quantity annually produced, commonly amounted to between fifteen and eighteen thousand quintals. 288 PHILOSOPHY OF soda, in quantity sufficient, and oniy sufficient, completely to dissolve and extract the resinous or beautiful red colouring matter; which is to be separated by draining, and the application of more water to the residuum, until the whole is abstracted and collected for use. To fit this co- louring matter for dying, the soda by which it was extracted, is to be neutralized bv an acid ; and for this purpose the citric acid is generally preferred to all others; and more especially that which is contained in lemons, or limes beginning to rot or spoil; or in their juice, when it has been kept some months in casks, and the mucilage has suffered a partial decomposition. Next to the citric acid, that of tamarinds, and of tartar, are thought most suitable; though Bergman has recommended the sulphuric, as next to the citric, if it be not used in excess. But Scheffer pretends that the acid juice of the berries of the pyrus acuparia, or mountain ash, produces a better, and more lasting colour than even the citric acid. The colour of safflower will not bear the action of soap, nor even that of the sun and air, for a long time ; and being more costly than even the colour of cochineal, it is principally employed for imitating upon silk the fine scarlet (ponceau of the French) and rose colours, which are dyed with cochineal upon woollen cloth. Beckman pretends that by preparing cotton as for the Turkey red, and dying it with safflower, the co- PERMANENT COLOURS. 289 lour was rendered much more durable, than it is by the ordinary process; but in this way it will cost so much, and after all prove so inferior, in point of durability, to the Turkey red, that this method of employing safflower, does not seem likely to be ever adopted. The fine rose colour of safflower, extracted by crystallized soda, and precipitated by citric acid, and then slowly dried in the shade, being afterwards finely ground with the purest tale, produces the beautiful paint by which ladies give to their cheeks the bloom of youth and health, and which the French distinguish from carmine by the name of " rouge vegetate." Aloes. M. Fabroni, in a memoir printed in the 25th volume of the Annalesde Chimie, has stated, that the almost colourless juice of the aloe succotrina' angustifolia, by exposure to atmospheric air, as- sumed a fine purple colour from an absorption of oxygene, and that he had dyed a beautiful and lasting purple with it upon silk, without any mordant or basis whatever, and in the 68th vo- lume (p. 165) of the same work, M. M. Bouillon Lagrange, and Vogel, have asserted, that nitric acid, heated with powdered aloes, produced a beautiful yellow powder, which, on being mixed with water, gave to the latter, a magnificently, rich purple colour: that a single atom was sufli- u 290 PHILOSOPHY OP cient to colour a large portion of water, and that the colour was so permanent, that when applied to the fingers, the stain continued several days, especially if a little alkali had been previously mixed with the powder. Encouraged by these statements I was induced, when this volume was nearly ready for a second impression, to rub, in a glass mortar, some of the best Barbadoes aloes, and pour upon it a little strong nitric acid, to which, after it had been mixed with the aloes, I added three or four times as much water ; and with this mixture farther diluted, I the next day dyed some pieces of white broad cloth and calico; the latter took only a sort of tobacco colour; but the cloth soon exhi- bited a rich, though brownish, purple, of consi- derable brightness, and which, after exposure to the sun and air during all the month of July (1812,) had suffered no change, excepting that it seemed, perhaps, half a shade darker and fuller than at first. I conclude therefore that this co- lour is eminently durable. It had, however, too much of the chocolate brown in its composition to be deemed a beautiful purple. 1 tried a simi- lar mixture, with a nitro muriate of tin, and with alum, but neither of them appeared to im- prove the colour in any way. I also tried it with sulphate of iron, which produced no change. How far it might be practicable to render this aloetic colour strictly a fine purple, and how PERMANENT COLOURS. 291 far, in point of cheapness, it would be advanta- geous for common use, are questions which I am not yet able to answer. Perhaps the more common Barbadoes aloes, might answer as well as that with which my experiments were made. I mean soon to ascertain this fact. Aloes powdered, and mixed with strong sul- phuric acid, produced only a snuff colour upon broad cloth, and with muriatic acid, it produced only a lighter brown ; the purplish colour before mentioned, is therefore an effect of the nitric acid alone. Orchall and Cudbear, The Linnean genus of Lichen, belonging to the natural order of algae, contains numerous species, of which several, after being macerated with ammonia or volatile alkali, afford beautiful violet, purple, and crimson, substantive dyes ; of these the most valuable is obtained from the lichen roccella, Linn, which in the quantity, vivacity, and durability of its colour, excels every other species of lichen; though unfortunately even this can- not be deemed a fast or permanent dye. Dr. Dilleniushas given an accurate figure and descrip- tion of it in his excellent and elaborate i( Historia Muscorum," Oxonii 1741. 4to. p. 120, tab. 17, Fig. 39, under the namcof coralloides corniculatum fasciculare tinctorium, fusci teretis facie." And he thinks, with reason, that it is the identical *- u 2 252 PHILOSOPHY OF 308 PHILOSOPHY OF Marking Nut. Or Semecarpus Anacardium. The tree which Linnaeus erroneously denomi- nated Avicennia Tomentosa, and which his son afterwards, with more propriety, called Seme- carpus Anacardium, produces a nut, which has been long known under the name of Malacca bean, or marking nut, from the use generally made of it throughout India, to mark calico and silk. The shell of this nut is composed of double lamina?, between which are many cells filled with a corrosive resinous juice, of a pale milky colour, until the nut has ripened, and then it becomes a brownish black. It is only soluble, as far as my knowledge extends, by the combined operation of alcohol and caustic alkali, neither of which, alone, will dissolve it; and being dissolved, it may be made to serve as an ink, probably of great durability, and inde- structible by any thing which will not also destroy paper* Osbcck says, that when the juice is employed for marking, the letters are commonly covered, while wet, with quick lime, to obviate the injury that might otherwise result from the corrosive property of the juice ; and it seems that quick lime is very generally employed for this purpose, in the way mentioned by Osbeck, or mixed with the juice before its application* By long keeping, this juice becomes as thick as tar, and in some of the nuts which were given to me, by a gentleman PERMANENT COLOURS. 309 in whose possession they had been for more than ten years, it manifested no acrimony to the taste. Some of it being topically applied to white calico, without any addition, it pene- trated thoroughly, and, being dried, it was after- wards boiled with soap, and exposed to the sun and weather, during two months, in which space the black colour had become deeper and more decided, as I presume, by an absorption of oxygene ; but as, from the viscidity of the juice, a redundance of colouring matter had been applied, the marks seemed rather to have been painted than stained or dyed. Dr. Roxburgh says, these nuts are employed by the Telinga physicians, to cure the venereal disease. They are also pickled like olives, whilst very young, and, when nearly ripe, arc applied as a mild caustic to sores, &c. Lamarck, and the French botanists, have restored to this tree, the name of anacardium, by which it was first distinguished, from the resemblance of its nut,, to the shape of a heart (somewhat flattened); and taking away this name from the Cashew tree, to which it ought never to have been applied, (as its nuts are kidney shaped,) they have denomi- nated the latter cassuvium pomiferum, which is the name formerly given to it by Rhumphius. Being at Barbadoes in the year 1805, a parcel of these nuts was given to me by Mr. Sim- monds, a very promising young botanist, (then in S10 PHILOSOPHY OF the family of the governor Lord Seaforth,) who was prematurely stopped in his pursuit of knowledge, soon after, by death, at Surinam. These nuts had been recently gathered, having grown on a tree in the garden of the govern? nient house, (pilgrims,) but were necessarily abortive, there being no male tree on the island. Their juice I found sufficiently fluid, though only of a dark-brqwn colour, when spread either on calico or paper, but it after- wards became black, by exposure to atmospheric air. Strong nitric acid changed it to an orange ; but oil of vitriol did not alter, though it weak- ened the colour, and this was the case when muriatic acid was applied to it. Muriate of tin produced no sensible effect upon it. This juice was a little acrid to the taste. There are a considerable number of other bles, whose juices by simple topical ap- plieation permanently stain linen or cotton, and the stains, by exposure to the atmosphere, generally become black, or nearly so. One of these is the amyris toxifera, or poison ash, which Catesby (vol. 2, p. 40,) has described as a fw toxicodendron foliis ajatis fructu purpureo," &c. adding, that " from the trunk of this tree distils a liquid black as ink, which the inhabi- tants say is poison." " It grows usually on rocks in Providence, Ilathera, and other Ba- hama islands. It is also found in South Caro- lina and Georgia. PERMANENT COLOURS. 311 The camocladia integrifolia, called Burnwcod, or Papau wood, and by some Maiden plum!}, in Jamaica, abounds in a moderately glutinous sap, which, as Jacquin asserts, will grow black by exposure to atmospheric air, and stain the hands of adeep black colour, only to be removed, with great difficulty, by washing with so Another species of this genus, the camocladia dentata, growing in South America and. in Cuba, emits, when wounded, a viscid milky juice, smelling like human excrement, which, by exposure to the air, becomes black, and gives durable stains to linen, &c. as well as to the fingers. It is mentioned by Ulloa under the name of guao. Another species of this genus, Camocladia punc- tuata, or dotted stalked Eclipta, grows in the West Indies, and contains a thin greenish sap, which turns black by exposure to the air, and may be used as ink. Jacquin says, the negroes some- times endeavour to increase the blackness of their skins by washing with this juice. The Eclipta erecta (cotula alba Lin.) affords a juice which the inhabitants of Cochin China, as Loureiro asserts, (p. 50.*>,) employ to dye human and other hairs permanently black, and, therefore, call it ink plant ; " herba atramenti." Several species of the genus Rauwoliia abound in a glutinous milky juice, which blackens by exposure to the air, and gives lasting dark-coloured stains; one of these, R. 312 PHILOSOPHY OF canescens, (" le bois laiteux febrifuge," of Pouppec des Portes,) bears juicy black berries, which, at maturity, may be used as ink, without any preparation, and are said to give a lasting black stain to linen. The hippomane mancinella, or manchipeel tree, contains a very acrid juice or sap, which, if in cutting the tree, or otherwise, it falls on linen, soon produces a black stain, which afterwards becomes a hole, from the caustic qua- lity of the sap: probably lime would correct this, as it does that of the juice of the marking nuts. The terminalia vernix of Lamarck, (Tsi-Clm of the Chinese,) contains, in every part of it, a caustic mifky juice, which, exuding from the tree when wounded, thickens and becomes black like pitch, by being in contact with the air, and is used by the Chinese as a varnish for furniture. I could mention several other vegetables with similar properties, but believe it to be uune< jssary. PERMANENT COLOURS. air> CHAPTER VI. Of Mineral Substantive Colours. u Rien n'est plus facile dans les sciences fondles sur l'experience que dr block, Haussman recommmends Stahl's alkaline tincture of iron, made by dissolving that metal in aquafortis, and adding to it carbonate of pot-ash in excess, suflicient to decompose and re-dissohe the nitrous oxide of iron ; and after- wards thickening the solution with gum, &c; as usual. Commonly, however, a solution of iron by some of the vegetable acids (called iron liquor) is employed for this purpose, adding to it a portion of sulphate of iron, to increase its strength, when very full and deep stains are required. Iron dissolved by muriatic acid, assumes a greenish colour, and the solution being applied to linen or cotton, the oxide adheres permanently; and, by an accession of oxygene, affords a fine yellow stain. A single washing will how- ever so far affect the proportions on which this colour depends as to reduce it to the common iron-mould colour. Copper. Only two oxides, or compounds of this metal with oxygene, are known to exist; one of these, PERMANENT COLOURS. 319- naturally formed, is distinguished by the name of ruby copper ore. Its colour is a dark or brownish red ; though the artificial imitations of it have, I believe, never risen much above an orange colour. This native oxide is supposed to con- tain about eleven per cent, of oxygene; but neither it, nor any artificial imitation of it, lias yet, as I believe, been employed for a substantive colour in (King or calico print- ing. I however, very recently, and unex- pectedly produced, and Jived permanently upon calico, a brownish red oxide of copper, very nearly resembling the ruby copper ore in colour. It has withstood repeated washings with soap, and six weeks exposure to the wea- ther, Without alteration ; and may, I think, prove useful, by simple topical application, in calico printing; but in this instance, it was the result of a complicated mixture, made for another purpose, and I have not yet had time to simplify the process sufficiently. When I shall have done so, I intend to make it public. In appearance it resembles another very permanent colour, which I discovered twenty years ago, I mean the red prussiate of copper, to be men- tioned hereafter. The other oxide of copper is supposed to contain about twenty per cent, of oxygene; but it has'Tjever, I believe, been employed for dying or calico printing. 320 PHILOSOPHY OF The green colour exhibited by most of the preparations of copper, commonly results f? om the absorption, or addition of carbonic acid„ for which the oxides of copper have a marked affinity ; it may be produced also by the admix- ture of muriatic and some other acids. There is however, I believe, none of the acid green solutions of copper or its oxides, which after being applied simply to cotton or linen will bear to be washed with soap, though '.heir colours generally withstand the impressions of sun and air for a considerable time. But if liquid ammonia be saturated with copper, and thickened with gum, it may, by simple topical application, be fixed upon linen or cotton, where, by an evaporation of a part at least of the volatile alkali, and an absorption, probably, of both oxygene and carbonic acid, its blue colour will be changed to a green resembling that of verdigrise, or rather that of the mala- chite, which .will very sufficiently resist the impressions of sun and air, and bear a con- siderable number of washings with soap with- out being much weakened thereby. It may, therefore, be usefully employed in this way, especially upon fine muslins, by reason of the great delicacy of its colour, and the facility of its application. I have several times thought that an effect somewhat better had resulted, when, instead of dissolving the copper by am- PERMANENT COLOURS. 321 monia, I combined the latter with a nitrate of that metal. Verdigrise dissolved by ammonia, also produces good effects used in this manner. A similar beautiful, though pale green, may be substantively dyed upon woollen cloth, by the sulphate of copper with a sufficient portion of carbonate of lime, to neutralize the acid. This colour will not indeed bear the action of soap, but it does not appear to suffer any con- siderable change or diminution, by the impres- sions of sun and air for a long time. The oxides and solutions of copper are all susceptible of combination with most of the adjective colouring matters, and may be usefully employed as mordants or bases with some of them, which will be duly noticed hereafter. Gold. When this metal is dissolved in nitro-muriatic acid, the result, as Proust has observed, seems to be a pure and simple muriate of gold : and when beaten into leaves, and burnt by electricity, or calcined by the sun's rays, concentrated and reflected by a burning mirror, it affords a purpk oxide : and this it also does when precipitated from aqua-regia by the muriate of tin. In this last operation, as well as in the former, the pur- ple colour depends entirely upon the oxide of gold ; that of tin,, though combined with it, being colourless. This precipitate has been 322 PHILOSOPHY OF called the purple of Cassius, though improperly ? because it was known to earlier chemists, par* ticularly Neri, Glauber, and Kunkcl. The supposed oxides, or precipitates of gold, ob- tained by mixing either of the alkalies, or lime or magnesia with a solution of gold, arc yellow ; but such precipitates appear (as Davy has ob- served) to be triple compounds. Having soaked muslin in a diluted solution of gold by aqua regia, for a single minute, I exposed it whilst wet to the direct rays of the sun in the month of September, and found, in less than a quarter of an hour, that the fine yellow colour which it had received from the muriate of gold, was become partially violet, excepting only a few round spots, to which I had previously applied a solution of crystals of soda thickened with gum ; in these spots the alkali had neutralized the acid, and produced a colour resembling that of bright iron-mould, upon which the rays of the sun made no impression, or change ; the violet colour, so produced, soon became general, excepting the spots last mentioned ; and, by a further exposure to the sun's rays, this colour was gradually reddened, and converted to a sort of crimson purple, in consequence, as I presume, of a farther de-oxygenation of the metal, which, from this progressive change of colour, appears to be susceptible of different degrees of oxidizement. A similar change was PERMANENT COLOURS. 323 produced, much more expeditiously, when I applied a recently-prepared muriate of tin to cotton, impregnated with a solution of gold in aqua-regia, and dried in the dark ; an abstrac- tion of oxygene, and a partial revival of the gold, having been almost instantaneously mani- fested, by the appearance of a violet colour, where the muriate of tin had been applied, and in no other part. Count Rumford, also, (as is stated in the Phil. Trans, for 1798) produced a purple colour by impregnating white silk, linen, and cotton, with a solution of gold, and ex- posing them to the direct rays of the sun, but he had previously separated a great part of the nitro-muriatic acid, employed to dissolve the gold, by evaporating the solution to dryness, and afterwards re-dissolving the oxide, or salt of gold, in water ; a precaution which I did not employ. He found, (as I have done) that no change of colour took place in the dark ; but here it must be observed, that he made no trial of the de-oxygenating power of the muriate of tin, which, when employed by me, readily produced the violet colour without the aid of light.* * More than half a century ago, Hellot had observed that characters traced on writing-paper with a diluted nitro-muriate of goild began, after a few hours exposure to the air, (he should have said light,) to manifest colour, and soon after became of a very/ dark violet — " violet fonce presque noir.'* But when shut uip in a close box, he says, the writing did not becomt Y 2 PHILOSOPHY OF Antecedently, however, to count RumforcFs experiments, Mrs. Fulhame (in an essay on combustion, published in 1794) had given an account of several ingenious attempts not only to fix the oxides of gold upon silk, but to re- vive the gold afterwards with its metallic lustre, principally by the application of hydrogene gas, and phosphuretted hydrogene, which in some degree produced the desired effect, though it was found impossible to make the revivification so generally equal, as to produce that uniformity of gilding, which could alone compensate the expence of it. In consequence of Mrs. Fulhame's publication, count Rumford attempted a more complete re- vival of gold, by mixing with his aqueous solution of its salt (before mentioned) sulphuric ether, which soon attracted and united itself with the gold, swimming upon the surface and leaving the water colourless : and this mixture being afterwards exposed to the rays of the sun, the metal soon revived in the form of gold leaf. Such a mixture of sulphuric ether and the salt of gold has lately been found useful to gild the points of lancets, and protect them from visible during several months. And he adds, that the lik« happened to characters written with a diluted nitrate of silver, though they became very visible in the space of an hour when ex- Dosed to the sun's rays. See Mem. de l'Acad. R. &c. 1737. PERMANENT COLOURS. 325 rust ; and if the expence be not too great, I am persuaded that white silks might be permanently gilt with it, in spots or figures, for which a per- fect equality in the metallic appearance of the gold would not be required. That precipitate of gold by tin, which has been commonly called the purple of Cassius, was soon after its discovery combined with glass to imitate Rubies, which it did perfectly, at least in their appearance, though not in their hardness ; and in later times, this precipitate has been generally employed as a finer sort of enamel for porcelain, &c. By varying the pro- portions of tin, or rather of its solution, the colours of this precipitate may be varied through all the intervening shades from violet to crimson; and the precipitate, with all its va- rious colours, may be permanently fixed as a stain or dye upon silk, linen, or cotton, by applying to them, either the solution of tin first, and afterwards the solution of gold ; or the solution of gold first, and afterwards that of the tin : it will be advantageous, however, to let the silk, &c. to which one solution has been applied, become dry before the second is superadded. Lately Haussman has found means to pro- duce a purple mixture of tin and gold, without any precipitation, by dissolving the metals with a great excess of the acids ; which excess re- 326 PHILOSOPHY OF tains the oxides, suspended in the water, not- withstanding their union, and such a partial de- oxygenation of the gold, as is necessary to its violet colour. In this purple liquor diluted, silk may, as he says, be made to receive the most durable co- lours, by repeated immersions, &c. which are, as I presume, necessary, by reason of the redundant acidity of the liquor. I do not, however, think that any benefit can result from thus applying the solutions of these metals mixed, and at the same times, rather than separately ; for in the latter way two immersions will be sufficient : and it is to be feared that this purple from gold, notwithstanding its great beauty and durability, will prove too costly for any thing, but a par- tial application in spots and figures. In my judgment the principal, if not sole use of the solution of tin, in producing this purple, is that of abstracting oxygene from the gold ; an effect which may be produced by other means. I have repeatedly found, that when a solution of gold in aqua-regia w r as ap- plied to, and suffered to remain upon my fin- gers, they received a purple stain which nothing could remove, but an abrasion or wearing off of the skin ; and I have produced a similar effect from a solution of gold applied to silk, cotton, and linen, previously impregnated with matters suited (in like manner) to abstract oxygene ; PERMANENT COLOURS. 327 «uch as animal glue, lintseed oil, caustic alkalies, yolks and whites of eggs beat up with sugar, or with orpiment, alkaline sulphurets, &c. &c. ; and, ceteris paribus, I have found that the more the oxide of gold was deprived of oxygene, the more its colour approached to the crimson. Silver. The colours to be obtained substantively from the metals, excepting those of iron and copper, chiefly depend upon a partial revival of the metal, which revival cannot take place, without its abstraction or separation from the acid by which it has been dissolved; and to promote this abstraction, it is convenient and sometimes ne- cessary to impregnate the linen or cotton in- tended to be dyed or stained, with some of the animal, alkaline, and de-oxygenating substances just mentioned, as contributing to precipitate and partly revive the oxide of gold. This observation is particularly applicable to the oxide of silver, which is properly of an olive-brown colour, but is rendered almost black by being deprived of a part of its oxygene, and thereby in some degree restored to its metallic form. The powerful efficiency of the sun's rays in the de-oxygenation of silver has been already noticed at p. .53 and 54. Leeuwenhoek mentions (Philosoph. Transact. vol. xxiv.), that by touching nitrate of silver, 326 PHILOSOPHY OF his fingers were stained black ; and that, finding it impossible otherwise to remove the stain, he cut off and burnt the skin, and then examining it by a microscope, he found the silver revived in a multitude of little globules. — " I have ly- " ing on my desk (continues he), a linen hand- " kerchief, which was stained with aqua-fortis. " impregnated with silver, with a large black " spot about as large as a shilling;" and he adds, that having ineffectually tried to discharge the colour by six washings, and by laying the handkerchief out to bleach, he cut out the stained part, burnt it to coal, and viewing it by a microscope, saw thousands of fine silver glo- bules therein. The effect here mentioned to have been produced upon the skin, accords with that which solutions of silver are known to pro- duce in blackening hair, and other animal sub- stances ; but in reading this account, I thought it extraordinary that clean linen, impregnated with no animal, inflammable, or alkaline mat- ter, should so far deprive nitrate of silver of its acid, as to produce the effect described ; and I repeated the experiment several times without success. At length, however, I took a silver tea-spoon, which had stood half filled with aqua- fortis for several weeks, and which on the hol- low inside was become almost black by it, and by the oxygene of atmosphere which it had at- tracted, and having poured out the more fluid PERMANENT COLOURS. 329 part of the solution, I rubbed a bit of cambric against the wet oxidated hollow surface, and hanging it up for a few days in the open air, on the south side of a wall, I found the cambric permanently stained of a very dark violet co- lour. A fine piece of cotton, however, by the same means received only a very slight disco- loration. But cotton, when impregnated with soda and the acidulous arseniate of pot-ash, acquired a strong durable slate colour by being- touched with diluted nitrate of silver; a drab colour by the same means, when impregnated with soda and sugar ; a dark olive brown, with sulphuret of pot-ash (liver of sulphur), and spirit of wine; and the like with soda, liver of sulphur, and sugar; and being impregnated with white of egg, beat up in water with sugar, the cotton received from the nitrate of silver a very strong brownish black ; and when caustic vegetable al- kali was added, it became a little blacker. The yolk, instead of the white of egg, produced nearly the same effect. All these colours were often washed, and exposed for a long time to the weather, without being changed.* * During the last twenty years an ink has been sold, and extensively used for marking linen, &c. which it does perma- nently, by means similar to those just mentioned. To prepare this ink, a white precipitate of pure silver is procured, by dis- solving that metal in nitric acid, and afterwards separating it from its alloy, by suspending in the solution, a thin slip of 330 PHILOSOPHY OF Mercury. The oxides of mercury very easily give up their oxygene, and are, therefore, readily precipitated by the means before mentioned, upon vegetable as well as animal substances, af- fording generally either black or dark colours, though of but little permanency, because the residue of their oxygene soon separates, and the mercury recovers its fluid metallic form. Ni- trate of mercury applied to cotton, which had been impregnated with soda, produced at first a yellow, which soon changed to an olive, and being washed with soap, to a full black colour ; but after a few days exposure in the open air, it almost entirely disappeared. On cotton, im- copper, which by its greater affinity for the acid, throws down the silver in the form of a white powder, which powder being afterwards mixed with an aqueous solution of white glue and gum arabic, forms the ink. But to render this preparation effectual, the linen, &c. to which it is applied by the pen, must have previously received an impregnation like some of tho*e which I have recently described, though they are, in this, rendered less necessary, because the precipitate of silver retains but a small proportion of acid, as is manifested by its want of solubility in water, which makes it expedient to shake the mix- ture as often as it is used. The impregnation most commonly employed seems to consist of isinglass, and white animal glee dissolved in spirit of wine, which being applied to the part in- tended to be marked, is suffered to dry j after which i t is fit to be written upon with what is called the ink. Additional means have been sometimes employed to increase the blackneft of the latter, but their effect will not last. PERMANENT COLOURS. 331 pregnated with soda and sulphuret of pot ash, it immediately produced a black, which, by wash- ing and exposure in open air, changed in about ten days to an olive, and soon after disappeared. On cotton, impregnated with sulphuret of pot- ash and spirit of wine, it also produced a black, which disappeared like the former; and with caustic vegetable alkali it produced nearly the same effect. With orpiment, dissolved by pot- ash, it produced a very deep black, which stood two or three weeks exposure to the weather ; af- ter which the mercury began to revive, in very small globules, and the colour to disappear in spots.* Platina. This metal was first discovered at Choco and Santa F6, in South America, and was not known to exist naturally in any other place, until Vau- quelin lately detected it among the grey silver * I have now before me some very Hack writing upon calico, which states itself to have been written with a solution of ni- trate of quicksilver, upon calico impregnated by a mixture of soda, liver of sulphur, and sugar, in water : seventeen years have elapsed since this writing was performed, and there is no appearance of that revivification of the mercury, which I had experienced when it was used upon calico with impregnations differing but little from that last mentioned. Professor Gmelin of Gottingen, in his publication, " de tin- gendo per nitri acidum," kc. mentions the staining of silk with a copper colour by mercury, dissolved in nitric acid. 332 PHILOSOPHY OF ores of Guadalcanal in Estremadura ; and more recently Dr. Wollaston has examined, and de- scribed a small specimen, which had been found in Brazil, intermixed with palladium. See Phil- Trans. 1809- Proust says, the result of a solution of pla- tina in the nitro-muriatic acid, is (like that of gold so dissolved) a pure and simple muriate. The oxide of platina, at the maximum of oxygenation, is of a yellowish brown colour ; but when heated and deprived of about one haif of this portion of oxygen e, it becomes green. Having immersed a bit of fine calico in a diluted solution of platina, by nitro-muriatic acid, it acquired a yellowish orange colour, and this being afterwards dried, I dipped it into a diluted solution of tin by muriatic acid, to see what effect would result from an abstraction of oxygene (which I expected) by the latter ; and to my surprise, I saw the colour instantaneously changed to that of arterial blood. This calico being afterwards dried and washed with soap, its beautiful red was thereby made to incline very much to a bright full orange colour, which did not change by subsequent washings, and seems to be permanently fixed. Though somewhat costly, it probably may be susceptible of some useful application to fine muslins in calico printing. In the production of this colour, the solution of PERMANENT COLOURS. 333 tin seems to act as it does in producing a purple with gold. The solution of platina (without that of tin) being applied to calico, produced a yellow colour, which, when washed, seemed to be per- manent, though it was afterwards raised to a bright high orange, by applying to it the solu- tion of tin last mentioned. The same solution of platina, being applied to calico, which had been soaked in a prussiate of lime, produced a brown colour, which, by washing with soap, became a dark violet, which seems to be permanently fixed. Similar effects were afterwards produced by the prussiate of pot-ash. Other pieces of calico impregnated severally with sulphuret of pot-ash; with soda, and the acidulous arseniate of pot-ash ; with orpiment dissolved by liquid pot-ash ; with liverof sulphur and alcohol ; and with lintseed oil ; and after- wards soaked in the before-mentioned solution of platina diluted, acquired different shades of purple, olive, and brown colours, which, when washed with soap, appeared to be permanently fixed. Manganese. The great variety and mutability of colours afforded to water, in different proportions, and of different temperatures, by manganese in com- 334 PHILOSOPHY OF bination with pot-ash, was long since observed by Glauber, as is noticed at page 18 of this volume. Whether the alkaline solutions of this oxide are capable of being usefully employed to dye substantive colours, I am unable to decide; my experiments therewith having been too few. I have found, however, that a considerable variety of lasting brown, or dark- coloured stains, may be produced upon bits of linen and cotton, which have previously and severally received the different impregnations before mentioned, by applying to them a diluted sulphate of manganese ; and without any such impregnation, if the latter be applied to linens or cottons, and they be afterwards dipped into a weak solution of pot-ash or soda, a yellowish brown colour will be produced ; and this, by attracting oxygene, will gradually change to a dark, and very durable brown. But if to this otherwise lasting dark colour, a solution of tin by muriatic acid be applied, it will restore the former yellowish brown, by causing an abstrac- tion of oxygene from the manganese ; though the latter by its affinity for oxygene will after- wards repair this loss, and by doing so will restore the former dark brown colour. Cobalt. The nitrate of cobalt may be decomposed by liquid pot-ash, and it will then afford ablueprc- 2 PERMANENT COLOURS, S3; cipitate, which if secluded from atmospheric air will hecome violet, and. afterwards red. Nitrate of cobalt applied to cotton, impreg- nated with soda, with soda and acidulous arse- niate of pot-ash, and with caustic vegetable alkali, produced lively pink and rose colours, which stood washing and exposure to weather for a considerable time. The oxide of cobalt, dissolved by muriatic- acid, and applied to cotton impregnated with soda, when held to the fire, exhibited the most beautiful green, which, as the cotton cooled, changed to an apple- green ; then passed through all the shades of yellow, and became a kind of pale buff colour, which the oxide retained after the cotton had been washed with soap ; but then on being heated, it was found to have lost the property of becoming green, though on dipping it into a diluted muriatic acid, it imme- diate^^ regained and exhibited the same pro- perty. These effects are connected with those which similar solutions of cobalt produce as sympathetic inks; though I confess myself dis- satisfied with all the explanations hitherto given of them. The presence of muriatic acid is essential to their existence, the nitrate of cobalt producing no such phenomenon ;* nor did I * Hawing lately soaked a bit of calico in a diluted nitrate of cobalt, jt exhibited a pale rose colour, when dried. To the 336 PHILOSOPHY OF find that the presence or absence of light haid any effect in retarding or promoting any of the changes of colour here mentioned. Nickel. If this metal be dissolved by nitric acid, the solution may be decomposed by pot-ash, and a grass-green hydrated oxide will be thereby obtained. By impregnating calico with a mix- ture of soda and sugar, and immersing it in a diluted solution of nickel by the nitric acid, a similar green was produced on the calico; but it did not prove sufficiently durable, to be em- ployed in dying or calico printing. Molybdena, titanium, palladium, and osmium, afford coloured oxides of considerable beauty and variety, which probably might be applied and fixed upon silk, linen, and cotton, were not calico so coloured I applied a solution of tin by muriatic acid, in spots, and afterwards holding the calico to the fire, I soon observed that these spots were all of a most beautiful blurish green, whiist every other part retained its rose colour. By removing the calico from the fire, and letting it cool, the spots again became rose-coloured. Having afterwards rinced the calico in water, the parts which had been spotted lost the power of becoming green when healed ; but by wetting them with muriatic acid, they regained this power, a proof that this acid, and not the tin dissolved by it, had, in the first instance, tnabled the fire to produce the blueish green colour. £ PERMANENT COLOURS. 337 these metals too scarce and costly, especially the latter, for this use. Berthollet has mentioned, (Ann. de Chimie, torn, i.) that the simple mixture of an oxide of lead with lime, will blacken wool, hair, &e. and that some persons have used it to render grey hairs black. Wishing to ascertain its effect in dying, I boiled flannel in lime-water with litharge, which produced a tolerable black upon the flannel ; and this black was not diminished by washing the flannel with soap, and exposing it for the usual time to the weather : strong acids, however, dissolved the lead, and discharged the colour : and the lime was found to have weakened the texture of the flannel consi- derably, and more especially when orpiment was added; an effect similar to that which it produces in those depilatory compositions which were brought to Europe from Turkey. Perhaps my readers may think, that many of the preceding experiments are such as the great Bacon (Lord Verulam) has termed " expe- riments of light rather than of fruit ." But such experiments are not to be neglected in a work which professes to treat of the Philosophy of Colours, though they should not be susceptible of any considerable practical advantage, or application. With this observation, I finish my account of substantive colouring matters. They claimed 538 PHILOSOPHY, &c. my earliest notice, because their properties and modes of application are generally the most simple and intelligible; and because some of them, particularly the oxides of metals, may also be made to serve as the bases of adjective colours ; which will become the subject of our next inquiries. IND OF PART I. PART II. EXPERIMENTAL RESEARCHES CONCERNING THE PHILOSOPHY OF PERMANENT COLOURS. PART II. CHAPTER I. Of Adjective Colours generally, and their bases ; with an illustration of their effects upon each other, as exemplified by Oriental and European calico-printing. *' Les faits sont de tons les temps, ils soul immuables, comme la " nature dont ils Bontlelangage j mais les consequences doivent " varier scion !'6tat des connoissances acquires. " Chaptal, Ett mens de Chimie. Adjective colouring matters are generally soluble, in a great degree at least, by water; though some of them derive their solubilitv from an intermixture of what has been called extractive matter; which being separated in the dying process, after the adjective colour has been applied to the dyed substance, their union becomes thereby more intimate and permanent. But in other respects, adjective colours owe their durability, as well as their lustre, to the interposition of some earthy or metallic basis ; which, having a considerable attraction, both for the colouring matter and the stuff to be dyed, serves as a bond of union between them, 342 PHILOSOPHY OF and obviates that disposition to suffer decompo* sition and decay, which naturally belongs to such colouring matters when uncombined. These earthy and metallic bases, having been com- monly employed in a state of solution or com- bination with acids, were from that circum- stance denominated mordants (biters or cor- roders) by the French, who, indeed, began to employ the term long before any thing like a true theory of dying had been conceived ; whilst even alum was supposed to act by its sulphuric acid, and not by the pure clay upon which its usefulness depends, and whilst in truth all the other matters called mordants were Supposed to be useful only by their solvent or corroding powers ; and the term, having been thus employed, has been since adopted in other countries. The ingenious Mr. Henry, of Man- chester, has, however, lately objected to it, with great reason,* and proposed in its stead to employ the term basis, which seems defective only, inasmuch as it does not express the par- ticular affinity, or power of attraction, mani- festly subsisting between these earthy and metallic substances, and the several adjective colouring matters, as well as between the former * See his " Considerations relative to the nature of Wool, Silk, and Cotton, as objects of the Art of Dying, &c." id tb* third vol. of the Memoirs of the Manchester Society. PERMANENT COLOURS. 343 anc the fibres of wool, silk, cotton, &c. I confess, however, that no other more suitable term has occurred to me ; and being unwilling to propose new terms, without some cogent reason, I shall sometimes employ that of mor- dant as well as that of basis ; though not indis- criminately in all cases ; since I shall generally use the former to signify earthy and metallic substances when actually dissolved by some acid, alkaline, or other solvent, and when of course they will commonly prove more or less corroding or biting, according to the original meaning of the term. But the denomination of basis will be most frequently used to designate the same earthy and metallic substances, dis- tinctly and separately from any acid or other sol- vent, when actually fixed in the pores or fibres of wool, silk, &c. or when it is not intended to notice any property in them, which may more immediately result from their combinations with any particular menstruum. M. Berthollet, indeed, gives the term mordant a much more extensive signification, as meaning all the dif- ferent chymical agents capable of serving as intermedia between the several colouring par-> tides and the stuffs so dyed with them, either for the purpose of assisting their union, or of modifying it.* This last effect (of modification) * " L'on donne le nom de mordant aux substances qui 344 PHILOSOPHY OF may, however, be produced by a variety of matters besides those which are of the earthy or metallic kinds, and indeed by every thing capable, not of fixing", but of merely varying, the shades of adjective colouring matters. These, therefore, I think it more proper to designate, not as mordants or bases, but as alterants* whose use and application may in this respect be extended to substantive as well as to adjective colours. The bases pre-eminently useful with adjec- tive colours, are the earth of alum, and the oxides of tin and iron, held or applied in solu- tion by an acid menstruum : and, excepting the process for dying black upon woollens and silks, it is generally deemed most advantageous to combine these bases first, and separately, with the stuffs to be dyed, superadding the colouring matters afterwards ; because the affi- nity or attraction of the basis, is commonly greater for the latter, than for either wool, silk, cotton, or linen ; particularly that of the earth of alum, which, when applied subsequently to, servent d'intermedes entre les parties colorantes et les etoffes que Ton teint, soit pour faciliter leur combinaison, soit pour la modifier." Elemens de I' Art de la Teinture, torn. f. p. 26, of the first edition. * M. Berthollet, in his last edition, torn. i. p. J\, has adopted the term of alterants, and employed it in the way which I had wggested, as above, in my first publication. PERMANENT COLOURS. 345 and upon the colouring matter, forms with it a kind of lake, by which their respective affini- ties are in a great degree exerted towards, and saturated by each other ; and the size of their particles being thereby increased, they do not penetrate copiously into, nor combine intimately with the fibres of wool, silk, &c. ; but remain in a great degree suspended in the dying liquor, or precipitated to the bottom of it. But by com- bining the basis previously, and separately, with the stuff to be dyed, and afterwards applying the colouring matter, this last, when so applied, is powerfully attracted by the conjoined affi- nities of the former, so that the dying liquor may be completely exhausted, and made co- lourless thereby. It must, however, be noticed in regaTdf to Wool, that by reason of its greater attraction for metallic oxides, they may, without any consi- derable disadvantage, be applied to it, in con] junction with adjective colouring matters, as will be mentioned in regard to the dying of scarlet and some other colours. It ought also to be observed, that when colours are dyed upon wool, silk, &c. by the aid of an aluminous or metallic basis, the colour is ap- plied, or dyed more immediately upon the latter, than upon the wool or silk, &c. as will be made evident hereafter. The durability therefore of an adjective colour must depend, not only on the S46 PHILOSOPHY OF natural stability of the colouring matter, but also upon the energy of its affinities, both for the stuff which is dyed, and for the basis or intermedium upon which it is immediately applied, and which, by its own peculiar attrac- tions, binds them to each other. The true nature and uses of mordants or bases, for the purposes under consideration, can, I believe, in no way be so distinctly manifested, or so clearly illustrated, as by their effects in what I shall call topical dying, or that species of it by which different colours are communicated to particular spots or figures on the same piece of cotton or linen, according to the several bases previously applied thereto, and which principally constitutes that truly wonderful art, tlt^art of calico-printing. I shall, therefore, in this place, bring under my reader's notice some of the more important operations of that art, reverting at the same time, as far as we can, towards its remote origin, in order to see how, and by what means, it has attained its most important improvements. Pliny describes the Egyptians as practising a species of topical dying, or calico-printing, which, as far as can be discovered from his ge- neral terms, appears to have been similar to that which, many ages after, was found to exist in Hindostan and other parts of Incia, and was from thence introduced into this and PERMANENT COLOURS. 347 other countries of Europe. He says, the Egyp- tians began by painting or drawing on white cloths, (doubtless linen or cotton,) with certain drugs, which in themselves possessed no colour, but had the property of attracting or absorbing colouring matters. After which, these cloths were immersed in a heated dying liquor; and though they were colourless before, and though this dying liquor was of one uniform colour, yet when taken out of it soon after, they were found to be wonderfully tinged of different colours, according to the different natures of the several drugs which had been applied to their different parts ; that these colours, so won- derfully produced from a tincture of only one colour, could not be afterwards discharged by washing ; and he considers it as admirable,~t?fat the dying liquor, which, if cloths of different colours had been put into it, would have con- founded them-all, should thus produce and per- manently fix several colours, being itself only of one.* * " Pingunt et vestes in jEgypto inter pauca mirabili ge- " nere, Candida vela postequam attrivere illinentes non colo- €l ribus, sed colorem sorbentibus medicamentis : hoc cum " fecere, non apparet in velis : sed in cortinam pigmenti fer- €f ventis mersa, post momentum extrahuntur picta. Mirumque, " cum sit unus in cortina color, ex illo alius atque alius fit in *' veste, accipientis medicamenti qualitate mutatus : necpostea " ablui potest. Ita cortina noa dubia confusura colores si " pictos acciperet, digeret eos ex uno, pingitque dum coquit." Punh, 1. xxxv. cap. ii. 543 PHILOSOPHY OF Whether the Egyptians borrowed this won- derful art from the Hindoos and other inhabi- tants of India, or whether the latter borrowed it from the Egyptians, is a question which pro- bably may be answered without much difficulty, if we consider the many reasons which exist for believing that this art has been practised over a great part of India during a long succes- sion of ages; that not only the art itself sub- sisted there, but that the colouring and other materials for exercising it, were the natural and peculiar productions of that country, rather than of Egypt; that the Indians were highly civilized at least twenty-two centuries ago, du- ring which space of time their manners, sancti- fied (if I may so express myself) by being con- nected to their religion, suffered little, perhaps no change; that their trades were carefully per- petuated in particular families; and also that among these their manufactures were undoubt- edly of very great antiquity, whilst obvious ways, by which they might have been easily extended to Egypt, and other countries, un- doubtedly existed long before the time when Pliny wrote. Major Rennell observes, that " a passion for " Indian manufactures and products has ac- " tuated the people of every age, in lower Asia, " as well as in the civilized parts of Europe: " the delicate and unrivalled, as well as the PERMANENT COLOURS. 349 u coarser and more useful fabrics of cotton of " that country, particularly suiting the inhabi- " tants of the temperate regions along the Me- " diterranean and Euxine seas. To this trade " (continues he) the Persian and Arabian Gulfs " opened an easy passage; the latter particu- " larly, as the land carriage between the Red " Sea and the Nile, and between the Red Sea " and the Mediterranean, took up only a few V days. It is highly probable, and tradition in " India warrants the belief of it, that there " was from time immemorial an intercourse be- " twecn Egypt and Ilindostan, at least the " maritime part of it; similarity of customs in " many instances, as related of the ancient " Egyptians by Herodotus, (and which can " hardly be referred to physical causes,) exist- " ing in the two countries." — " It would ap* tl pear, that under the Ptolemies the Egyptians " extended their navigation to the extreme iC point of the Indian Continent, and even ". sailed up the Ganges to Palihothra." See Me- moir and Map of Ilindostan, &c. 4to. by James Rermell, F. R. S. The best accounts of the practice of calico- printing* in the East Indies, were given in cer- * I here continue to use this term, though in truth none of the mordants or colouring matters, employed to stain the calicoes of India, were applied bv engraved blocks or plates as in Europe., but by the pencil. 550 PHILOSOPHY OF tain letters, written by Father C a mis- sionary at Pondicherry, (published iu the xxvith Volume of " Recueil des Lettres Edifiantes., " &c.") with the supplemental remarks and corrections of Mons. Poivre ; and in a manu- script account procured from thence by Mons. Du Fay, and communicated to the Royal Aca- demy of Sciences at Paris, by the Abbe Mazeas ;* and also in the report made in 1735 by M. Beaulieu, (then a captain in the French navy) of the operations which, at the request of Du Fay, he caused to be performed under his own inspection, at Pondicherry, and by which a piece of chintz was completely printed or stained of various colours, as described in a little publica- tion, entitled " Trait.6 sur les toiles peintes, dans lequel on voit la maniere dont on les fabrique aux Indes," &c. From these several accounts, as well as from some valuable private informa- tion which I have been able to procure, the fol- lowing concise statement has been composed, of the principal operations by which the chintz calicoes of India received the colours for which they were highly celebrated before the art of * " Itecherches sur la cause physique de l'adherence de la couleur rouge aux toiles peintes qui nous viennent descotea de Malabar & de Coromandel :" par M. l'Abbe Mazeas, corres- pondant de l'Academie, &c. Mem. des Sfjavans Etrangers, torn. iv. PERMANENT COLOURS. S51 calico-printing had been introduced and simpli- fied in Europe. The cotton cloths, when brought from the weaver, partly bleached, were worn next to the skin, by the dyer and his family, during the space of eight or ten days ; after which they underwent several macerations in water with goat's or sheep's dung, accom- panied by frequent intermediate beatings, washings, and dryings (by exposure to the sun.) Afterwards they were soaked for some time in a mixture of the astringent external part of the fruit of the yellow myrobalan tree,* (separated * The fruits of several trees not yet accurately distinguished, or ascertained, have been called myrobalans : that species which ishere meant, belongs tothegenus terminalia, towhich the trivial or specific name of chebula, or that of citrina has been applied. See Retzius's Observations. It is the ladamier of the French, and her of the Hindoos. The ripe fruit is yellow, and pear-* shaped, with five longitudinal angles ; and, when dried, appears wrinkled. It consists of a white pentangular nut, covered by a mucilaginous and highly astringent substance, nearly two lines in thickness j and within the nut is a small white oily kernel. The nuts are separated from the astringent substance which covers them, by bruising the fruit under a wooden roller or cylinder, it being the external astringent substance only, or an infusion or decoction then of, which is generally employed throughout India for dying or calico-printing, and which, by Very decisive experiments, to be mentioned hereafter, 1 have found to be capable of answering all the purposes of galls. Indeed, the leaves of this tree afford a sort ot fiattish yellow irregular galls, produced by the punctures of a particular species of insect ; which galls are collected and sold in all th« 352 PHILOSOPHY OF from the nut and powdered) with buffaloes* milk ; and being thoroughly penetrated and im- pregnated therewith, they were taken out, and the liquor being well squeezed from them, they were again dried by exposure to sun-shine, and afterwards, by pressure and friction, with wooden rollers, they were made smooth enough to be drawn upon by the pencil, with the different mordants (according to patterns previously traced out and marked by powdered charcoal). The first of these mordants was an iron liquor (acetite of iron), similar to that since employed by the calico-printers of Europe, excepting only that, instead of vinegar or alegar, the iron was dissolved by a mixture of sour palm wine, and of water in which rice had been boiled.* This bazars or markets : they are called allccay by the Telingas, of Hindoos of the Circars, and cadacay or caducay by the Tamuls : and they produce with iron a strong durable black dye, and ink ; and with alum a very full, though dark brownish yellow. If hese galls were bruised so as to occupy less space than they otherwise must, by reason of the cavities contained within them, they might be advantageously imported into this country, as might also the external astringent substance of the fruit of the tetminalia chebula separated from its riseless nut. By some persons the unripe fruit is preferred, as having most acerbity or astriogency. * In the letters of Father Coeurdoux, the water in which rice had been boiled, and which was converted to a sort of vinegar, is termed canje, and the vinegar from palm wine is named callou. In these, bits of old iron and the vitrefied mat- ter of a smith's forge powdered, were macerated and exposed PERMANENT COLOURS. 353 liquor was applied to the figures or spots in- tended to be made black, by a combination of the oxide of iron, with the colouring matter of the myrobalans. By this method of producing black stains, the colouring matter is applied previously to the metallic basis, contrary to the practice in regard to most other colours. But in this the strong attraction of oxide of iron for the fibres of cot- ton, as already mentioned, obviates the evil which would result from a similar application, where other mordants were intended to follow. When the black figures or stains have been thus produced, the blue are next to be given, and as a preparation for this, it is thought ne- cessary to remove the astringent and oily mat- ters which the calico had imbibed in every part, by being soaked in the mixture of buffaloes' milk, and powder of myrobalans ; and for this purpose it is macerated during 24 hours in the dung of goats, or sheep, diluted with water, then rinced thoroughly and repeatedly in clean water, and dried in the sun : after which the figures intended to be made blue, are marked by outlines traced with powdered charcoal mixed with a solution of gum ; and this being done* to the sun, until a sufficient solution had been effected. Ac- cording to Dr. Roxburgh, the Telingas give the name of cassim to their solution of iron, made by palmira toddy, or the juice •f Borassus tlabelliforrais, (a species of palm) turned to vinegar. a a 354 PHILOSOPHY OF every other part not intended to be made blue, is covered with melted wax, to protect it from the indigo ; and then the calico is sent to the blue dyer, and by him immersed in the cold indigo vat described at p. 203 ; and being suffi- ciently dyed, the wax is afterwards removed by covering the calico with boiling water, which melts the wax, and this last rising to the top, is separated when the water cools. But as the wax cannot in this way be completely removed, the calico is again soaked in a mixture of goats' or sheep's dung and water, rinced, dried in the sun, beat and afterwards soaked and boiled in water with olla, or washermen's earth, (which seems to be a natural mixture of soda and chalk) then macerated in water with cow-dung, and again well rinced, dried in the sun, and beat. After all these operations, the calico is again to be impregnated with the same oily and astringent matters which were removed to make Avay for the indigo blue, by soaking it again in the mixture of buffaloes' milk and my- rohalan powder, drying and making it smooth, as before. And this being done, the calico will be in a fit condition to receive the aluminous mordant, upon which the red is afterwards to be dyed; which mordant is to be applied according to figures marked out with powdered charcoal : and when purple and violet figures are to be produced, they are to be' in like manner PERMANENT COLOURS. 355 designated ; and for these, a mixture of the solu- tion of iron, with the aluminous mordant, in suitahle proportions, is to be applied ; whilst for the figures intended to be red, the aluminous mordant alone is employed as a basis. These mordants are commonly applied by children, with the pencil, or with pointed wooden sticks. To prepare this aluminous mordant, two ounces of alum were dissolved in two quarts of water, taken from certain pits, which water Father Coeurdoux has called " apre," probably because it held in solution a little soda, which there abounds in many places. To colour this solution, so that the strokes of the pencil in ap- plying it might be visible, a little sappan or sampfan wood (coesalpinia sappan of Linn.) in powder, was steeped in the solution, which be- ing afterwards strained, was applied as before mentioned ; after which the cotton so penciled, was exposed to the hottest sun-shine, in order that the parts to which the mordants had been applied, might he dried as much as possible; and then the cottons were thoroughly soaked in large pits of water, to cleanse them from the loose superfluous parts of the different mor- dants, as well as from the buffaloes' milk, &c. ; and this being done, they were slowly dyed in water moderately heated, with certain roofs an- swerinff nearly in their effects to those of mad- der. Of these there are several sorts used for a a c 2 356 PHILOSOPHY OF dying red in different parts of India, whick will be more particularly noticed hereafter ; that pointed out by the accounts in question, and most commonly employed, is called on the coasts of Coromandel and Malabar by the names of chay, chaia, chayaver, chailliver, and raye de chaye.* And after being dyed, the cottons underwent three different washings with goats' dung, soap, &c. and were then bleached by being exposed to the sun, and watered oc- casionally, to remove the stain on the parts in- tended to be left white. /It appears, that in this operation the buffaloes' milk, and more especially the astringent juice of the myrobalans, produced very beneficial and important effects, by their attraction for the aluminous earth, which contributed greatly to decompose or separate it from the sulphuric * This root was supposed, by M. M. Poivre, Hellot, and others, to be a species of galium or lady's bed-straw ; afterwards, however, M. Duhamel de Monceau thought there was suffi- cient reason to consider it as the Hedyotis herbacea Lin. : lately, however, Dr. Roxburgh has ascertained it to be a species of oldenlandia, to which he has annexed the specific name of um- bellata ; (see Plants of Coromandel, vol. i, p. 3, t. 3.) This indeed belongs to the same class and order as the galium and hedyotis (i. e. to the tetrand. monog. Lin.) ; and is called tsheri- vello by the Telingas ; che, saya-ver, and imbourel, by the TamuLs. Since my former publication on this subject, I hav© made numerous experiments with this toot, of which an ac- count will be given hereafter. PERMANENT COLOURS. 357 acid, and consequently to fix it more firmly in the cotton ; and being so fixed, it was enabled more strongly to attract and retain the colour- ing* matter of the chay root when in the dying vessel, and thereby to produce a more perma- nent red colour in the different spots, figures, or designs, where the alum liquor had been applied.* The astringent or colouring matter of the myrobalans also contributed essentially to pro- duce the purple and violet stains, upon the parts or figures to which, for that purpose, a mixture of iron liquor and of the aluminous mordant had been applied, as lately mentioned ; the chay root not having (as my experiments prove) the property, like madder, of producing those colours with iron. After these operations, a yellow composition was applied by the pencil, &c. to the parts which had been preserved white ; and when a * When a solution of alum is applied to calico which has received no impregnation, it will not be sensibly decomposed ; but on the contrary, a great part of it will again crystallize, so soon as the water which held it in solution has evaporated ; and none but very feeble colours can be raised upon such a basis. But when calico has been impregnated by such astringent and animal matters as are obtained from myrobalans and buffaloes' milk, the alum will not only be decomposed, but the alumine will combine with the astringent and oily matters so obtained, and a basis will be laid for a colour almost as durable as the Turkey red. 358 PHILOSOPHY OF green was wanted, to other parts which, with a view to that colour, had been dyed blue. This yellow composition was made by dissolving powdered alum in a decoction of the powdered galls of the myrobalan tree, called uldtcay by the Telingas, Sec. as just mentioned. In making this decoction, powdered turmeric and dried pome- granate rinds were sometimes put into the water, with the aldecay. But the yellow or green result- ing from this application, will only endure a few washings, before it becomes almost obliterated, pather Cccurdoux pretends, indeed, that this de- fect may in a great degree be obviated by mix- ing with the yellow in question, some of the astringent juice of the root of the plantain (musa) ; but if this had been true, such mix- ture would doubtless have been employed, and in that case the yellow of the Indian chintz would not have proved so defective, as it is known to have been at all times. In this composition we have an adjective colour directly combined, and topically applied with its basis, instead of being applied sepa- rately, as is most usual. Such compositions (which will be frequently mentioned hereafter) assume the form of a substantive colour, with- out being such in reality ; and as it may be use- ful to distinguish them by an appropriated term, I beg leave to call them pro-substantive topical colours, and to apply that designation wherever PERMANENT COLOURS. 359 an adjective colour, and its basis or mordant, are thus mixed and applied together topically, either by the pencil or the block. The art of calico-printing, since its intro- duction to Europe, has been divested of many tedious operations and manipulations, which in- deed would have proved insupportably expensive here, on account of the higher price of labour, and of almost every thing necessary to human subsistence.* But the greatest European im- provement in this art, respects the aluminous mordant, and depends on the employment of sugar of lead (acetite of lead), or the oxide of that metal dissolved by distilled vinegar, and crystallized ; which within the memory of man has been gradually brought into use, without any theory, or even suspicion of its true effect, or of the way in which it has proved so highly useful. This improved aluminous mordant is now generally made by dissolving three pounds of alum in a gallon of hot water ; then adding one pound, or in some particular cases one pound and a half, of the acetate or sugar of lead, stir- ring the mixture well during two or three days, * Berthollet, torn. i. p. 8, of his last edition, has delivered a similar opinion, and he adds in a note, " Cette opinion est con- firmee par les details plus exacts que Ton trouve dans Bancroft Of Permanent Colours." — He considers the art of dying in India as being now nearly in the state in which it was at tht time of Alexander's invasion. 360 PHILOSOPHY OF and afterwards adding to it about two ounces of pot-ash, and as many of clean powdered chalk (carbonate of lime). In this mixture, both the alum and the sugar of lead are decomposed by a double elective attraction, which produces two new compounds, according to Mr. Henry and M. Berthollet, because the oxide of lead hav- ing a stronger attraction for the sulphuric acid than for that of the vinegar, combines with the former, and, forming an insoluble salt, sub- sides to the bottom of the liquor, whilst the eartb of alum, thus left in a very divided state, unites to, and is dissolved by the acetic acid, previ- ously separated from the lead, and remaining in the liquor, which thereby becomes a diluted acetate of alumine ; the pot-ash or chalk only serving to neutralize the excess of sulphuric acid, which is always contained in alum, and which would in some degree hinder the alumine from being deposited and fixed in the fibres of linen and cotton. But the decomposition here described takes place only in part, because one pound of sugar of lead, or even one and a half, (the greatest quantity any where proposed,) is not sufficient to decompose three pounds of alum. On the contrary, I have found that alum cannot be completely decomposed, without nearly its weight of sugar of lead :* and where * Having added a pound of sugar of lead to a pound of alun? PERMANENT COLOURS. SGI less has been used, I have always been able, by evaporation, to detect a quantity of it in the aluminous mordant. I shall have occasion hereafter to revert to this subject, and shall therefore content myself at present with remark- ing, that the printer's aluminous mordant is not, in fact, a mere solution of the alumine, or earth of alum, by the acid of vinegar, as those emi- nent chemists Mr. Henry and M. Ber thallet have supposed ; but that even with the greatest pro- portion of sugar of lead ever employed by the calico-printers, it contains a considerable por- dissolved in hot water, I found that though the alum was de- composed and a pure acetate of alumine produced, yet the acetic acid, which had dissolved the lead was not sufficient to re-dissolve the whole of the alumine, a pari ot t bavins sub- sided with the sulphate of lead 5 it was, however, goon dissolved by adding vinegar to it; and this solution, when made with strong vinegar, proved as efficacious as the purcacetate of alu- mine in fixing the colours of madder, &c. Gay Lussac has observed that an acetate of alumine, which when cold is perfectly transparent, becomes turbid and depo- sits a part of its alumine when heated, and tha if left to cool again, the aluminous sediment will be re-dissolved, and the liquor recover its former transparency : a:i effect which he thinks analogous to the coa"gulatio.. of aii;umin,>u}, matter by beat, of which he has given an explanation t p '07 of the 74th volume of the Annales de Chimie. The .ric bowwer it may be explained, enables us to understand (u .,.* experience had in some degree previously suggcted) i/vh> the ajr urinous basis should not be applied warm, when it is intended to be copiously fixed on calico, under the operation of printing. 3€2 PHILOSOPHY OF tion of alum in its original state ; I mean that in which the argillaceous earth oralumine is comhined with sulphuric acid. But, notwith- standing this circumstance, I shall generally consider this preparation as being in reality, what it is not strictly, an acetate of'alumine ; and shall commonly distinguish it either by that name, or by that of the printer's aluminous mordant. The mixture or mordant in question being thus made, and the clear liquor decanted from the sediment, it is afterwards thickened with flour,* if intended to be printed or applied by * Since my former edition, it has been found that by slightly torrefying the flour, it was rendered more soluble in water, and more suitable for the purpose of giving consistency to the mordant in question ; and the brown colour which it ac- quires by torrefaction supersedes the use of Brasil wood, and other colouring matters, to mark the parts which have received the mordant. Starch, by a similar torrefaction, softens, swells, and emits a penetrating odour ; and, the torrefaction being then stopped, a substance is obtained, which has been lately much employed by calico-printers as a substitute for the guru of Senegal, under the name of British gum. From half to three quarters of a pound of gum have com- monly been found necessary to each quart of the mordant, according to the season of the year, and the sort of figures or impressions intended to be made. So much consistency should be always given to the liquor as will hinder it from spreading beyond its proper limits, taking care at the same time, that it shall retain so much fluidity, as thoroughly to penetrate the fibres of the calico, and, in the language of the printers, serve as a leader or conductor to the aluraine, &c. PERMANENT COLOURS. 3fi3 the block and with the gum of the mimosa nilotica (gum arabic), or of the mimosa Senegal (gum of Senegal), if it be intended for pencil- ing ; and being applied in either of these ways to linens or cottons, previously bleached and made smooth by the cylinder, the latter are to be thoroughly dried* by a stove heat of 150 deg. of Fahrenheit, and afterwards put into a cop- per partly filled with a mixture of cow dung and water, through which they arc to be turned by the winch, backwards and forwards, until the gum or flour employed to thicken the mordant has been dissolved, and the loose particles of alumine separated ; that they may not in the dying vessel combine with the colouring matter, and discolour the grounds intended to be pre- served white. The cow dung in this operation was supposed to be useful only by combining with, and entangling the superfluous parts of the mordant, so as to hinder them when scpa- tated from the figures to which they had been first applied, from attaching themselves impro- perly to other parts, and becoming the basis of an unpleasant stain, But there is reason to believe that cow dung, by the gastric juices, * This thorough desiccation, by artificial heat, contributes very much towards a more perfect union of the aluminous and ferruginous bases with the fibres of the cotton, by^ausing an evaporation of the acetic acid, and also of the water, which by their affinities, would obstruct the desired union. i 36"4 PHILOSOPHY OF gelatine, and albumen, which it contains, affords a very beneficial impregnation to the printed calico, of some animal matter, which combi- ning with the mordant, serves to bind it more strongly to the printed calico, and afterwards to increase its attraction for the colouring matter, like some of the animal impregnations which are so necessary for the Turkey red.* * Mr. Watt has supposed that the animal gall contained in cow dung, exercises a particular power in this operation, of se- parating the acetic acid from the alumine, and that by com- bining with the latter, it renders it more efficacious afterwards, in attracting and holding the colouring matter in combination. Mr. Widtner, of Jouy, near Versailles, has entertained nearly a similar opinion, (as Berthollet reports) ; he believing that, " dans le bouzage il se forme une combinaison triple de la matiere animale avec l'alumine et la toile, qui ajoute a la beaute des couleurs :" and for this opinion, Berthollet thinks there is some foundation, because water alone does not answer the purpose j and he adds, that an examination, not indeed the most minute, of cow dung, did not enable him to discover in it anything likely to produce these beneficial effects, excepting a matter analogous to bile, " une matiere analogue a la bile." Elemens, &c. torn, i, p. 90. Haussman substituted powdered chalk for cow dung (with water) ; but found the colours which were raised afterwards upon the aluminous basis to be very feeble, though those upon the oxide of iron, which had at the same time been subjected to the action of chalk and water, did not appear greatly de- fective. Soap and water being employed instead of cow dung and water, produced effects more hurtful to the aluminous basis than those of chalk and water. If cow dung were only useful by thickening the water, oatmeal, or the meal of lint - seed might well supply its place ; but I have not found them capable of doing so. PERMANENT COLOURS. 365 Subsequently to this dunging operation, the pieces of calico are to be well rinced, and beat in clean running water, to remove as far as pos- sible every loose particle of the mordant, which might otherwise, when in the dying vessel, occasion an improper stain. By thus substituting the acetic for the sul- phuric acid, in the aluminous mordant lately de- scribed, several considerable advantages are gained. The acetate of alumine being much more soluble in water than common alum, the liquor will contain a much larger proportion of alumine, than could be otherwise suspended in it ; and with this advantage, moreover, that it will not be liable to form crystals in or upon the linens or cottons in drying, as would happen with a solution of common alum, the acetate of alumine being incapable of crystallization. I may add also, that the acid of vinegar being volatile, and having a much weaker attraction for its earthy basis than the sulphuric acid has, the former will be speedily separated and carried off, especially by the heat of the stoves employed for drying the pieces printed with it, and will leave behind the alumine which it had dissolved, and which, being no longer encumbered by any other attraction, will yield itself wholly to that, which subsists be- tween it, and the fibres of linen or cotton, and will unite with them more copiously and firmly % SGG PHILOSOPHY OF than it otherwise could do, and be thereby enabled more strongly to attract and fix the colouring matters in the (Kins: vessel. This, however, will only prove true, so far as the sul- phate of aluminc has been really decomposed by the acetate of lead, or so far as the alumine has been combined with the acetic instead of the sulphuric acid** * Since these observations were first published, cheaper means have been discovered of forming an acetate of alumine. White lead, not adulterated by carbonate of lime, being dis- solved in strong vinegar, was found, in several experiments which I made, to answer the purpose of sugar of lead, and to produce a good aluminous mordant, by adding to the solution a suitable proportion of powdered alum ; and I afterwards found that litharge dissolved in vinegar, instead of white lead, was equally useful for decomposing alum. But soon after it had been ascertained, that the acid obtained from oak, beech, ar.d other woods, by converting them to charcoal in close vessels, and collecting the acid by proper tubes and receivers, was tray an acetic acid with only an intermixture of an empyreumatic oil, and perhaps a little ammonia, this pyroligneous acid w.is generally substituted for vinegar, and employed to dissolve the oxide or carbonate of lead: and the solution so made, was, with a considerable diminution of expence, employed :o decompose alum, instead of sugar of lead; the empyreumatc oil, excepting its unpleasant smell, doing little or no harm even to the most lively and delicate colours, and proving a some degree beneficial to those depending on a ferruginous basis. More recently, however, it has been discovered, that ty dissolving lime instead of an oxide or carbonate of lead, in tie pyroligneous or other acetic acid, alum might be still mo;© PERMANENT COLOURS. 3G7 As the practice of calico-printing has been but lately introduced into Europe, and as the acetated aluminous mordant does not appear to have been previously known in any other country, we might have expected that its dis- covery in this, would have been deemed a matter so important, as to have constituted an sera in the history of the art; and, therefore, I was not a little surprised in finding that no writer had mentioned, and that no calico-printer, of whom I have inquired, could inform me, at what time, or by whom, this mordant was first employed, as the basis of red and yellow colours in calico- printing. My wonder has, however, ceased on this subject, since I have inspected a consi- derable number of recipes for making the several mixtures employed as mordants, soon after the business of calico-printing began to be carried on with some degree of success here, and in other parts of Europe. In one of these, which seems to have been the earliest, alum, sal am- moniac, saltpetre, red orpiment, and kelp, were directed to be mixed with water. In another, which probably followed this, it was directed that these ingredients should be dissolved in vinegar. In a succeeding recipe, a little sugar cheaply decomposed ; and at present, an acetate of lime is, I. believe, generally employed, instead of the acetate of Jead^ t-9 produce the aluminous mordant. 368 PHILOSOPHY OF of lead was directed to be employed, but in a quantity too small to be of any considerable use ; I mean one ounce of it for every pound of alum. Afterwards, the calico-printers, without any system or reasonable motive, appear in dif- ferent instances to have added verdigrise, arsenic, corrosive sublimate, blue vitriol, litharge? and white lead. By stumbling upon the two last (which alone were of any use), it happened, where vinegar had been also employed, as it commonly was in some shape, that after a variety of decompositions and recompositions, some portion of acetate of alumine was formed, the good effects of which were experienced, though without any true kuowledge of the ways and means by which they had been produced. By degrees, however, the printers seem to have increased the quantity of sugar of lead, and several of them to have suspected that many of the other ingredients usually employed for making their mordants were useless. Some of them, therefore, began to omit one, and some another of these ingredients, until at length all the useless ones were laid aside, though without the aid of any chemical reasoning on the sub- ject, and without any one having ever suspected, as indeed few of them do at this day, that the lead which they continued to employ, occa- sioned any decomposition of the alum, or that the mordant so produced did not really contain PERMANENT COLOURS. 369 all the lead and other ingredients used to pre- pare it. Among the useless ingredients before mentioned, corrosive sublimate seems to have been retained the longest, since Mr. Wilson includes it in his recipe, which was published so lately as the year 1786. (See his Essay on Light and Colours, &c.) It is not wonderful, therefore, that no parti- cular person or period has been noted, or re- membered, as distinguishable for the first in- vention of the acetated aluminous mordant; since the sugar of lead, or other means of form- ing it, were at first used by chance so sparingly, as to have scarcely produced any better effect than would have resulted from the mere solution of alum, and the alterations and improvements by which the mordant afterwards acquired its present form, I had almost said perfection, were made by such imperceptible gradations, and re- sulted so much from the random additions and omissions of different individuals, (no one of whom seems to have been guided by any thing approaching to a just theory,) that neither the discovery, nor any considerable step towards it, can properly be referred to any one person or period. Mr. Henry, justly sensible of the superior advantages of the acetated aluminous mordant in calico-printing, and conceiving it to have really been very anciently known and employed b b 570 PHILOSOPHY OF in those countries where the art was first prac- tised, concludes from thence, that it must have resulted from a very advanced state of chemical knowledge in those countries, at some very re- mote period, which was afterwards lost, whilst the improvements arising from it in this respect continued to be practised and handed down, through a long succession of ages to the present time. " To have invented (says he) the process of printing, in the manner described by Pliny, the inhabitants of India must probably have known how to prepare alum ; they must have been acquainted with the manner of dissolving lead in the vegetable acids ; they must at least have been acquainted with the component partsof these salts, and they must have had a knowledge of double elective attractions, &c." In truth, however, the inhabitants of India neither had, nor have they at present, any knowledge of the use of sugar of lead, or of any other preparation of that metal which could produce similar effects in calico-printing; a solution of common alum in water being their only aluminous mordant, and the previous application of the soluble parts of myrobalans and of buffaloes' milk, to their calicoes, aided by a very hot sun- shine, and the complete desiccation which it produces, enabling them, without any thing like an acetate of alu- mine, to give equal durability to their colours. This tact I have learned, not only from all the PERMANENT COLOURS. 371 accounts published, or transmitted to Europe respecting this point, but from the positive ver- bal informations of eye-witnesses to the practice of calico-printing in that part of the world, and particularly of a gentleman of great veracity, as well as knowledge on this subject, who formerly carried on the business of calico-printing very extensively in Bengal (principally for account of the East-India Company) : and indeed sugar of lead is so far from being used for this purpose there, that within a few weeks I have received a letter from Mr. John Adie, (successor to the gentleman last mentioned,) dated, " Gondel- para, near Chandernagore, the 10th of February, 1792," and mentioning, that he had some little time before been obliged to pay twenty shillings the pound for sugar of lead, in order to prepare a particular colour which I had formerly recom-f mended: so far was this ingredient from being: in use there for any such purpose. We may, therefore, safely conclude, that the formation of an acetate of alumine, and its ap- plication as a mordant in calico-printing, was not an oriental discovery; and that it did. not result from any knowledge of double elective attractions, or any other extensive chemical knowledge, either in ancient or modern times ; since those who gradually stumbled upon and introduced the use of it, were totally ignorant of the decompositions and recompositions which Bb 2 372 PHILOSOPHY OF took place in their mixtures, and always sup- posed, as all other calico-printers have till lately done, and as most of them now do, that the alu- minous mordant really consisted of every thing used in producing- it. To illustrate more plainly the differences of colouring matter, as well as the action of an alu- minous hasis upon them, let us examine its effects in a few particular instances : taking a small piece of calico, upon which certain figures and designs had been printed with the acetated alu- minous mordant, and which, after being dried, had been cleansed in the usual way, I dyed it in water with saffron ;* the water readily extracted the yellow colour of the saffron, and the calico soon imbibed so much of the colour, as to be- come equally yellow in all its parts, without any difference of shade, even where the aluminehad been applied. The calico so coloured being ex- posed to air, soon became equally and uniformly white : the colourinsr matter of the saffron bavins: no affinity to the alumine : to see, however, whether this last remained fixed in the fibres of the cotton, I dyed the same piece which the saf- fron colour had thus abandoned, in water with a * The colouring matter of saffron readily dissolves in water, but is soon destroyed by the rays of the sun j it gives a rich yellow to linen, cotton, &c. but having no affinity for any kuown basis, it has no permanency, though it will acquire blueish and greenish shades, when acted upon by the sulphuric and nitric acids. PERMANENT COLOURS. 373 little Brasil wood, and the figures, where the alumine had been applied, became of a strong, full, and beautiful crimson; the other parts, to which no basis had been applied, being but slightly discoloured. The calico so dyed, being exposed to the sun and air two or three days, the spaces to which no mordant had been ap- plied, became perfectly white; and the figures impregnated with alumine, had lost some of their fine crimson colour, which gradually diminish- ing, by a continued exposure, was all gone at the end of eight days. In this instance, the aluminous basis had a certain affinity with the colouring matter of the Brasil wood, (which was not the case with that of saffron,) but not so much as to fix and retain it permanently. To ascertain, however, that the defect arose from the want of a sufficient affinity between the colouring matter and the alumine, and not be- tween this last and the cotton, I took the same calico, which had been already twice dyed, and dyed it a third time in water with madder, whereby the whole became, coloured, but the figures impregnated with alumine much more deeply than the other parts; a proof that the alumine still remained fixed", notwithstanding the escape of the Brasil wood crimson, and tint it had again entered into a triple combination with the madder colour, and the fibres, of the cotton. The piece so dyed, being well boiled 5 374 PHILOSOPHY OF in water soured with bran, and exposed to sun- shine and air, in a few days became white in the parts where no mordant had been applied to fix and retain the colour, whilst the figures formed by the application of alum in e, retained all their body and brightness; the colouring matter of the madder, in this triple combination, not being- liable to destruction or separation by the same means which destroyed or separated it where no such bond of union or means of preservation existed.* It has been already noticed, that in oriental calico-printing the solution of alum is coloured red with sampfan, or sappan wood ; and I might have added, that in dying with chay root, the red colour of the wood is dislodged from the pores of cotton by the superior attraction of the root colour, which takes its place. Neither the East Indians, however, nor the writers who have given accounts of their operations, seem to have been apprised of this fact ; hut have concluded that the red wood colour was fixed, and made durable by applying that of the chay root.j' To * M. Berthollet, in the last edition of his Elements, &c. (torn. i. p. bO) has introduced ray account of these experiments, to illustrate and prove the affinities of alumine employed as a basis, and also the different dispositions of colouring matters to be acted upon by these affinities. f This erroneous opinion has been again very lately propa- gated in a French periodical work, of considerable respectability, PERMANENT COLOURS. 376 ascertain the truth on this point, I made several experiments, of which an account was given in my former edition ; but they are now omitted, because those which I have since made with the chay root itself, and which will be stated here- after, must render the former unnecessary. After this account of the acetate of alumine, it is proper that I should notice that of iron, commonly called iron liquor, which, as employed in Europe, was manifestly borrowed from the Indians, with only the substitution of a vinegar from wine or malt, for that obtained by ferment- ing the juice of some of the different species of palm trees. The means of producing an acetate of iron, obviously presented themselves, and did not re- quire any more chemical knowledge, than people but very moderately civilized are commonly found to possess. Iron, in a state proper for being dissolved by vinegar, might be procured, (" Annales des Arts & Manufactures," No. 51,) where M. Le Goux de Flaix, in giving an account of the chay root, says, "This root is useful not to give colour, but only to fix that which has been otherwise given ;" and he adds, that by not knowing this fact, it was found impossible to make any use of a large quantity of the chay root, imported by the French East- India Company to France, in the year 1774. The true cause, however, of the failure here mentioned, will be explained here- after, when I shall have occasion to notice a similar failure, in regard to a recent importation into this country, by the English India Company. 37« PHILOSOPHY OF without a previous decomposition for that parti- cular purpose. But this was not the case with alumine, of whicti the nature was completely un- known, as well as the ways of procuring it; and even at this time, though we know it to be a particular and pure specks of clay, we do not find it either p men cable, or advantageous, to obtain it, except by separating it from the sul- phuric acid, with which it has been previously dissolved, and combined in common alum. The first European calico-printers, in making their iron liquor, employed many useless ingre- dients, as they also did in making the aluminous mordant. In the more early prescriptions 1 have found, besides old iron, and vinegar or sour beer, verdigrise, sugar of lead, blue vitriol, anti- mony, urine, the brine of pickled herrings, salt- . petre, sal ammoniac, and other incongruous mat- ters, frequently directed ; and they were thought to be useful, because they did not hinder the oxide of iron from performing its office as a basis. Rye meal was for many years very com- monly employed, and probably with some ad- vantage. Afterwards, however, experience, di- rected by the light of chemistry, enabled the manufacturers and consumers of this mordant, gradually to discard the useless ingredients em- ployed in making it, as they also did those which had for a considerable time encumbered, and in gome degree injured the mordant, from alum. PERMANENT COLOURS. 377 lion alone, dissolved by an acetous acid, then constituted the iron liquor; and to produce this acid, malt, or sour beer, or the washings of sugar hogsheads, were commonly employed, as being the most economical ; and broken iron hoops, or other thin pieces of old iron, were subjected to the slow action of the acid. And when a more concentrated solution was wanted, either as the basis of very full adjective colours, or as a sub- stantive topical colour, certain proportions of sulphate of iron were dissolved in the iron liquor, which, with or without this addition, always required to be thickened, like the alumi- nous mordant, when topically applied by the pencil, or printed by engraved blocks. I scarcely need to add, that since the nature fc>f pyroligneous acid was ascertained, this last has been preferred, as the cheapest, and in some respects most, useful, for making the acetate of iron, as well as that of alum ine. When pieces of calico have been printed with iron liquor, whether it be applied to those which either have received, or are intended to receive, the aluminous mordant also, they are to be tho- roughly dried by a store heat, and afterwards passed through the mixture of cow-dung and warm water, in the manner directed for pieces which have been printed with the acetate of alu- niine only, and with a view to similar effects ; and they are afterwards, in the language of the mm 378 PHILOSOPHY OF calico-printers, to be streamed, or extended, in running water, and beat, to remove all the loose or uncombined particles of the mordant, and thus fit them to be dyed, with either madder, sumach weld, or quercitron bark ; these being the prin- cipal, and almost the only adjective colouring matters so employed by calico-printers, and sufficient (excepting the blue from indigo) to produce, with the aluminous and ferruginous mordants, all the various colours seen and ad- mired on printed calico. E. G. If pieces of calico, to which these mordants have been applied, both separately and mixed, be put into a dying-vessel, with water scarcely blood- warm, and in which three, four, or five pounds of madder in powder, for each piece, have been previously mixed, and they be turned, as usual, through the liquor, by the winch ; gradually, but slowly, raising the heat, so that it may only reach the boiling point at the time when the calicoes will have been suffi- ciently dyed, the several pieces will be found to have imbibed colour in everv Dart. The frVures or places to which the unmixed iron liquor was applied, will have been dyed black, and those on which the aluminous mordant was printed, will be red, of differe'nt shades, if the mordant had been used at different degrees of concentration ; and, if both mordants were mixed and applied in different proportions, such applications will PERMANENT COLOURS. 379 have produced various shades of purple, violet, chocolate, and lilac colours ; whilst the parts, or grounds, intended to he ultimately left white, will manifest a considerable brownish red dis- coloration : but as the madder colour producing it, is not then united to the calico, by the affinity or attraction of any intermediate basis, it will not be able, as in other parts, to resist the action of exterior agents, and may therefore (as is usually done) be removed, and the grounds made white, by boiling the pieces in water soured by fermented bran, and by afterwards spreading them for some days (according to the season) upon the grass ; where, with the well-known treatment, the colours dyed upon a basis will become brighter, whilst that without one will completely dis- appear. Calico, printed with the same mordants, and dyed with the quercitron bark, (quercus tincto- ria, or quercus nigra, Linn.) will acquire fixed and bright yellow r s of different shades, upon the aluminous basis, and various drab colours upon that of iron. A mixture of these bases will produce olive colours. Along with these it is usual to produce black impressions at the same time, by previously applying to the calico a mor- dant composed of iron liquor and galls ; by which figures, which, without the galls, would only have manifested a dark drab colour, are made black, by dying with the quercitron bark; 330 PHILOSOPHY OF and if the dying be conducted as I shall here- after direct, the grounds will be so little disco- loured, that no exposure upon the grass will be required, as is necessary with madder and weld ; an advantage which has nearly put an end to the use of weld in calico-printing. This method, however, of dying yellow upon a basis, is an European invention; the people of India having only given it, as already men- tioned, by a pro-substantive mixture of the de- coction of the galls of myrobalans with alum. And, indeed, this practice was followed here for some time after the introduction of the art into Europe, excepting that, instead of the galls of the mirobalan tree, a decoction of French ber- ries (rhamnus infectorius, Linn.) was employed ; by which, indeed, a very full bright yellow was at first communicated, but of so fugitive a nature, that the use of these berries, which in some degree still subsists, ought to be discou- raged ; it being impossible, by any means yet known, to obtain from them a colour fit for any other purpose than that of deception. Hitherto, the art of calico-printing has been confined almost solely to linens and cottons, which are suited to it, by being susceptible of a permanent union with colouring matters, and especially with their bases, by only the common warmth of the atmosphere: and as this is also the case of silk, there can be no doubt but this PERMANENT COLOURS. 38 last might be made the subject of new and beau- tiful embellishments in that way, which, if pro- perly executed, would undoubtedly become a source of gratification to the public, and of profit to individuals. Very lately indeed a species of topical dying or staining, very much resembling some parts of calico-printing, has been ingeniously applied to woollen stuffs, and particularly those called kerseymeres, for waistcoat patterns, &c. What I mentioned in a former chapter, of the necessity of a considerable degree of heat, to enable the fibres of wool to receive and combine with colouring matters, will afford some idea of the difficulty of applying and fixing different colours in the form of spots or figures upon woollen stuffs in this way by dying ; the particular mode and means by which this difficulty is overcome, and the several colours fixed in the fibres of wool, are still kept secret as much as possible. How proper colours for this purpose may be pro- vided, either from substantive colouring matters, or from the adjective ones, made into the form of a strong decoction, and mixed with the proper mordants, (as in the instance which I lately noticed of a pro-substantive yellow,) will be easily understood by those who may attend to what has been, or will be, explained in the course of this work ; and such colours being so prepared, and printed upon kerseymere, &c. in 382 PHILOSOPHY OF the usual ways, may be, as I have found on trial-. and as I am informed they are, made to pene- trate and unite with the wool, by placing the stuff so printed in the steam of boiling water for a sufficient length of time, first wrapping it up in thick paper, doubled or trebled, so as to ex- clude the moisture, so far at least as that it may not occasion the colours to run beyond their proper limits. After this summary account of the origin, progress, and nature of calico-printing, intended to illustrate more distinctly the effects of the principal bases or mordants, it will be proper here to take a general view of the facts which respect the application of these bases, for fixing and modifying different adjective colours, not by topical, but by general dying, as well upon wool and silk, as on linen and cotton. The two last of these, spun into thread or yarn, and either woven or not, are made fit for the application of a basis, by being boiled, for the space of three or four hours, in a solution or lye of pot-ash or of soda, of suitable strength; then spread for some time on the bleaching- ground ; afterwards soaked in water, made sour by the addition of one-fiftieth, or sixtieth, of its weight of sulphuric acid, or oil of vitriol, and filially rinced thoroughly in clean water, and dried. When thus prepared, if the aluminous basis is intended to be applied to them, perhaps PERMANENT COLOURS. 383 there is no form in which it could be more effectual than that of the acetated aluminous mordant, though motives of economy have always induced the mere dyers of linen and cotton to employ cheaper preparations of that basis. The sulphate of alumine, or common alum, will indeed yield a part of its earthy basis to linen and cotton, when dissolved by water and applied to them ; but it does this more readily when deprived of its excess of acid by pot-ash or calcareous earth ; and it is in this way commonly employed as a mordant for linens and cottons. About four ounces of alum, with water sufficient to dissolve it, and half an ounce, or somewhat less, of pot-ash, are commonly allowed for each pound of linen or cotton in- tended to be dyed ; and the latter are to be ma- cerated, &c. in this liquor, cold, or only blood- warm, until thoroughly and equally penetrated by it, and afterwards well rinced, to separate the superfluous or loosely adhering alum, &c* Cotton, treated in this way, commonly gains * If, instead of the small proportion of pot-ash here men- tioned, so much of it, or of soda in its stead, were employed, as would suffice first to precipitate, and afterwards re-dissolve, the alumine, the latter, being then in a triple combination with the acid and alkali, would be less attached to either, and more readily, as well as copiously separated, and united with the fibres ©f linen or cotton. 384 PHILOSOPHY OF about, two and a half percent, additional weight by the alum, partly decomposed, which com- bines with it. But, where no white grounds are to be reserved, there are ways of separating the aluminous basis more advantageously, and applying it more efficaciously, particularly for madder colours upon linens and cottons, by im- pregnating them with oleaginous, astringent, glutinous, animal, and alkaline substances, which occasion an increased affinity or attrac- tion between the fibres of the linen or cot- ton and the colouring matters ; thereby form- ing, perhaps, a kind of cement, which renders them more fixed, and less liable to be acted upon and injured by those causes which generally destroy or weaken colours. These auxiliary means will hereafter be noticed in their proper places; and particularly when treating of the Turkey red. Silk is to be impregnated with the aluminous basis, by macerating or soaking it onhy, during the space of ten or twelve hours, in a saturated cold solution of alum. To impregnate wool or woollen cloth with the aluminous basis, it is commonly boiled in water, with from one-fourth to one-sixth of its weight of alum, and from one-twelfth to one- sixteenth of its weight of crude tartar, putting the latter first into the water, and, afterwards, the powdered alum : the heat of the water being PERMANENT COLOURS. 385 gradually raised, is kept at the boiling point for an hour and a half, or two hours, during which the cloth is turned through the boiling liquoron a winch, that the mordant may be equally ap- plied ; and being afterwards taken out and drained, it is commonly left until the next day, and then rinced in clean water, for dying. In the early collection of recipes, printed in 1605* and already mentioned, sour bran liquor is com- monly directed to be employed in this way with alum ; and it seems to have answered the pur- pose of tartar, which, when it came to be gene- rally used in this way with alum, was supposed by the older dyers to do good by softening and correcting the acrimony of the latter : probably, however, the purposes which it answers, are not yet clearly ascertained ; one of them seems to be, that of increasing the solubility of alum, and enabling it more completely and intimately to penetrate the fibres of the wool, with which it moreover enters into a permanent union, and thereby contributes efficaciously to modify, vary, and in some cases to brighten the colours with which it is employed, as will be seen here- after. It was until very lately believed, even by those who had most knowledge of the subject, that woollen cloth boiled in this way, with alum, decomposed the latter, in a considerable degree at least, attaching to itself the alumine, c e 386 PHILOSOPHY OF though not without a small portion of the sul- phuric acid in combination therewith.* Very recently, however, MM. Thenard and Hoard (of whom, the latter is director of the dying de- partment at the imperial manufactory of the Gobelins at Paris,) appear to have acquired more correct ideas on this point, by a scries of experiments, of which they have given a minute statement, in a memoir read at the Physical and Mathematical class of the French National Insti- tute, (see Ann. de Chimie, torn. 74, p, 26?.) These experiments were principally made with alum, acetate of aluminey tartar, and the solu- tions of tin, applied to wool, silk, and cotton ; and by these, it was fully ascertained, that alum and cream of tartar do not decompose each other when dissolved in water, and boiled with wool, (a fact which had, indeed, been previously asserted by Berthollet); that in this boiling, the wool combines with the alum, without decom- posing it in any degree,^ and also with the tar- * Berthollet, torn. i. p. 80, after saying, that in aluming stuffs the latter decompose the alum, and combine with the alumine, whilst the acid which held it dissolved, separates and remains in the bath, adds, " Mais il ne faudrait pas conclure de la, qu'aucune portion de l'acide ne reste dans la combinaison de 1 ctofFe ou elle peut avoir quelque influence sur la couleur." f It was completely ascertained, that when wool had been no alumed, the alum employed might be all recovered, partly from the bath or liquor in which the aluming had been per- PERMANENT COLOURS. 387 tar; that equal parts of alum and tartar would dissolve in two-fifths less of water, than would be required to dissolve them separately. They found that wool, as it is commonly cleansed for being- alumed, was not deprived of the carbonate of lime naturally combined with it; and that this wool, being boiled the usual time, with one-fourth of its weight of alum, and one-sixteenth of its weight of cream of tartar, rendered the bath, or water, troubled or muddy, and produced (as is, indeed, commonly observed) a copious white sediment, which being collected, washed, and analysed, was found formed, and partly from the wool itself, by repeatedly washing the latter in pure boiling water : commonly a dozen separate washings were sufficient to remove completely all the alum which had united itself to the wool; and the alum, so separated, was susceptible of a distinct crystallization, as if it had never been so employed. After the last of these washings, the wool or cloth, so washed, was found to be as incapable of receiving colours by dying, as if it had not been alumed ; and, indeed, before the last, it was always found, that the colour attempted to be dyed upon it, was feeble, in proportion to the number of washings which had taken place. It became evident, therefore, from these experiments, that wool or cloth boiled with alum (and tartar) attached to itself the undecomposed alum only, and that a decomposition of the latter does not take place until the subsequent operation of dying, w"hen the affinity of wool, being assisted in the dying vessel, by the affinity of the adjective colouring matter, their co-operation separates the alumine, in a great degree at least, from the sulphuric acid. e c 2 $m 3S8 PHILOSOPHY OF to consist, chiefly of a sulphate of lime, and a saturated sulphate of alum hie. That when wool had been properly cleansed, and deprived of its carbonate of lime, no sulphate thereof was found. Such wool or cloth, being boiled in pure distilled water, with the proportions just mentioned of alum and tartar, and the bath or liquor with which the boiling had been per- formed being carefully evaporated, a residuum was found, consisting of alum, cream of tartar, and a compound, difficultly crystallizable, of tartrite of pot-ash and animal matter. The. wool itself, when so boiled, afforded, by repeated "washings, alum, and a small quantity of cream of tartar, besides a very sour combination of tartaric acid, alum, and animal matter. As the acid of tartar combines so copiously with wool, MM. Thenard and Roard have inferred, that it ought not to be employed in this way with alum, except for colours which acids contribute to raise and improve : and among such colours they rank those of cochineal, kermes, and mad- der; but those of weld, logwood, and Brasil wood, not resisting acids as they suppose, wool intended to be dyed from either of these, ought, as they think, to be alumed, without any addi- tion of tartar. The accuracy of these opinions will be tried by facts, when the several colour- ing matters here mentioned shall claim our par- ticular attention. PERMANENT COLOURS. 3S9 These gentlemen did not find any advantage to arise by a prolongation of the boiling with alum and tartar beyond the space of two hours, nor by increasing the proportions of alum and tartar; but, on the contrary, thought they ob- served beneficial effects from a diminution of them with weld, logwood, and Brasil wood, but not with cochineal, madder, or kermes. Nor did they find any benefit produced, by letting the wool or cloth remain some days in the liquor with which it had been boiled, as some persons have advised. From these experiments, MM. Thenard and Roard have thoght themselves entitled to con- clude, with " certitude, que dans l'alunage dc toutes les matieres animales, Falun se combine en cntier avec elles, sans eprouver aucune decompo- sition, et qu'il forme alors des combinaisons plus ou moins solubles, qui ont pour les matieres co- lorantes une grande afhnite ;" and they have made a similar conclusion in regard to vegetable matters, (i. e. linen and cotton, &c.) ; having found that the latter, when carefully alumed, might be completely deprived of every particle of alum, by fewer washings than silk, and by much fewer than wool, which had been so alumed. They found also that, (as with silk,* * Silk ought never to be subjected to a boiling heat, either when the mordant is applied, or afterwards, in the dying open- 390 PHILOSOPHY OF and for similar reasons) it was always best to begin the dying of linen and cotton (when alumed) at a low temperature, and to keep the dying liquor considerably below the boiling point, until the colouring matters were enabled to attach themselves to the mordant, and pro- duce an insoluble combination therewith, pre- viously to its being subjected to the action of boiling water. These gentlemen, moreover, ascertained, that when acetate of alumine was applied to wool, silk, linen, and cotton, it combined with them entirely, undecomposed, like alum; but, being exposed to a warm atmosphere, a part of the acetic acid, from its volatility, soon evaporated, leaving behind an excess of alumine, which could riot, like the mere acidulated acetate of alumine, be carried off by boiling water: a fact which accords with the explanation lately given of the utility of this mordant in calico-printing. In regard to the solutions of tin, it appears, that woollen cloth, boiled with them in water, and the proportion of tartar which is commonly employed in dying scarlet, combined with the acids, as well as with the oxide of that metal; tion j where a high temperature, besides injuring the texture and lustre of the silk, would detach and separate the mordant, before the colouring matter could have combined and produced an insoluble union with both. PERMANENT COLOURS. 391 and that by numerous washings afterwards with distilled water, boiling hot, all these matters were completely separated ; and that, by evaporating the washings, they were collected in the form of tartaric acid, and muriatic acid, combined with tin ; while the mother water contained (as was also ascertained by evaporating it) tartrite of pot- ash, acidulated tartrite, and a very acid mu- riate of tin. It results, therefore, from these experiments, that wool has no more power to decompose the solutions of tin, than it has to decompose those of alum; and that, when not assisted by the affinity of some colouring matter, it unites with both the tin and the acids, holding them in solution. The different solutions of tin, the best means and methods of producing them, and their re- spective effects in dying, will be noticed here- after ; and more especially when I come to treat of the dying of scarlet with cochineal, for which that metal was first employed as a mor- dant, and with advantages so remarkable, that the discovery of its use for that purpose, may be considered as an important icra in the his- tory of this art. The mordants afforded bv iron, when em- ployed upon wool and silk, are commonly ap- plied either subsequently to, or interchangeably with the colouring matters intended to be fixed or modified by that basis, as will be more parti- 392 PHILOSOPHY OF cularly explained, when the dying of black claims our attention. It will be ascertained hereafter, by my own particular experiments, that all the metals, pro- perly so called, as far as they have been tried, are capable of attracting adjective colouring matters in some degree, and of serving as bases to them ; and this is also true of most of the earths; though none of them is so efficacious and useful in this way as alumine; indeed this, and the oxide of tin, seem to be the only bases suited, by their perfect whiteness, to reflect the rays of light so as to exhibit adjective colours with their utmost lustre and brightness, every other falling short of these in that respect, and almost all of them appearing to sadden or darken the colours which they serve to fix. Probably, the oxides of zinc and antimony do this less than any of the others : the former, however, (zinc) does not appear, by my experiments, capable of giving much stability and permanency to any colour dyed with it. After this general explanation and illustration of the properties and uses of mordants or bases in fixing and modifying adjective colours, I shall next proceed to a particular inquiry concerning their effects upon each of the more important dying drugs of this class, beginning with those which belong to the animal king- dom. PERMANENT COLOURS. 393 CHAP. II. Of Adjective Colours from European Insects, and principally from the Kermes, or Coccus Ilicis, Linn. " La lame et la soie qui raontreroicnt plittot dans leur couleur natu- u relle la rusticity dc l'age, que l'esprit de Phomme et la politesse " da siecle, n'auroient qu'un mediocre commerce, si la teinture " ne leur donnoit des agr£mens qui les font rechercher et desi- " rer, memo par les nations les plus barbares." Colbert, Instruction ge'ne'rale your la Teinture, Sfc. 1672. Among animal adjective colours, the kermes are entitled to ovwjirst notice, because they appear to have been used for dying at a very early pe- riod ; and, like the nmrex and buccinum, were probably first employed for that purpose by the Phoenicians. Being unacquainted with the oriental languages, I can only adduce to this point the opinions of others, better qualified than myself in that respect. One of these is Professor Tychsen, (quoted by Professor Beck- man, vol. ii. p. 185 of the English translation of his History of Inventions,) who says, that among the Hebrews, the kermes dye was men- tioned, under the names of " tola schani, or sim- ply tola, by their oldest writer, Moses ;" that " tola is properly the worm" and that " the addi- m& 394 PHILOSOPHY OF al word schani, signifies either double dyed, or, according to another derivation, bright, deep, red dye ;" that for the shell " purple, the orientals have a particular name, argaman, or argevan, which is accurately distinguished from tola ;" — - w all the ancients, therefore, translate the Hebrew word tola, by xo*xo ?; kermes, zeliori, and zehorito, (deep red, bright dye,) which words they never put for argaman." After these and other observations, he concludes, that " the scarlet, or kernies dye was known in the East, in the earliest ages before Moses ; and was a discovery of Phoenicians in Palestine, but certainly not of the small wandering Hebrew tribes." That " tola was the ancient Phoenician name used by the Hebrews, and even by the Syrians ; for it is employed by the Syrian translator, Isaiah, chap. i. V. 18." — " Among the Jews, after their captivity, the Aramcean word zehori was more common." Bischoffalso maintains, that the kermes red dye was meant by the Hebrew words tholaat schani, in several parts of the Old Testament. It may, therefore, be assumed, that the colour which is mentioned in Exodus, chapters xxvi. xxviir. and xxxix. (as one of the three which were prescribed for the curtains of the taberna- cle, and for the " holy garments " for Aaron,) and which the English translators have ren- dered by the word scarlet, (as they have done PERMANENT COLOURS. 3D5 in other parts of the Old Testament) was no other than the blood-red colour, dyed from the kermes. Indeed, the colour now denominated scarlet, and dyed from cochineal, upon a tin basis; had not been discovered when the last English version of the Bible was made, in the reign of James the First. The Greeks appear to have obtained a know- ledge of the kermes, and their use in dying, at a much later period ; and we find this insect denominated wxxo* 0«p.M> by Dioscorides, iv. 48, p. 260, and by other Greek writers : whence the Latins derived their names of coccum or or coccus, with the addition of infectoris, or infectorium. Pliny, as I have noticed at p. 125, mentions the kermes as being sometimes em- ployed, conjointly with the colour of the murex and bucciuum, in producing a sort of purplish crimson, called by the Romans hysginus. He adds, upon that occasion, that this drug was brought from Galatia, or from the vicinity of Emerita, in Portugal, and that the latter was the most commended.* And again, in his xvith book, chapter viii., after describing various uses or products of the oak, he mentions the coccum, or kermes, as being the most excellent ; adding, that it is an excrescence, produced upon * " Coccum. Galatise rub ens granum" — "aut circa Emeri- tam Lusitaniae, in maxima laude est." Plin. Hist. lib. ix. c. 41. msmm mmmMmmmmBmtm 396 PHILOSOPHY OF the stems of a small shrub, called the ilea? aqui- folia ; — but of such value, that the people of Spain are enabled to discharge half their tribute by it; and that it is also produced in Galatia, Africa, Pisidia, &c. Lastly, Pliny, in the second chapter of his twenty-second book, after noticing the great improvements which had been then recently made in the art of dying, mentions (while he professes to pass over) the grains brought from Galatia, Africa, and Portugal, and appropriated for dying the imperial robes, 8cc* The ancients had but very incorrect notions of the kermes, many supposing them to be the grains or fruit of the ilex. They saw, indeed, that insects were ultimately evolved or produced from them; but believing, as they did, that insects might be spontaneously generated by corrup- tion, this evolution did not appear incompatible with their supposition, that the kermes was properly the grain, or berry, of the tree on which it was found. From the name of enccum or coccus, cloth dyed red with kermes was designated by the sub- stantive coccinum, and the adjective coccinus, or coccineus ;\ and persons wearing such cloth * " Atque at sileamus, Galatiae, Africae, Lusitanise granis, coccum imperaloriis dicatum paludamentis," &c. f Corresponding designations were given in the original Greek, as well as in the Latin version of St. Matthew, xxvii. PERMANENT COLOURS. S9t were said to be coccinati, according to the follow- ing line of Martial, viz. " Qui coccinatos non putat viros esse." It will have been seen, by the passages which 1 have recently quoted from Pliny, that the appellation of granum was given by him to the kermes insect, doubtless, from its resemblance to a grain or berry ; and this appellation has been continued by succeeding writers,* and, doubtless, occasioned the colours dyed from the kermes to be called grain, or ingrain colours, as those of cochineal afterwards were, from a similar mistake, which for some time subsisted, concerning the nature of that insect. By a succession of observations, however, it seems to have been ultimately ascertained, that the worm or insect was the most important part of the supposed grain or berry in producing the kermes red, and, therefore, in what have v. 28, to the role which our translators denominate scarlet, and with which the soldiers clothed and derided Jesus, when, having " platted a crown of thorns, they put it upon his head, and a reed in his right hand, and they bowed the knee before him, and mocked bim, saying, Hail, King of the Jews." The fact shews, that the kermes red was then considered as an attri- bute of royalty. * In modern times, the kermes have bean called by the Italians, gran a da tintore ; by the Spaniards, grana de line tores; by the Freach, grains d'escarlate ; and by the English, keraces ktrries. 598 PHILOSOPHY OF been called the middle ages, this production was frequently denominated vermiculus, or ier- miculum, and the cloth dyed with it vermiculata ; and heaee ultimately originated the French word vermeil, and that of vermilion derived from it. The Spaniards, and through them the other nations of Europe, appear to have obtained the name of kermes from the Arabians, who, ac- cording to their own accounts, were made ac- quainted with it, as well as the substance, by the Armenians* and Persians, among whom * Beckman says, that J. Beithar, in Bochart Hierozoicon, ii. p. 625, calls kermes an Armenian dye j and that the Arabian lexicographers, from whom Giggeus and Castellus made ex- tracts, explain the kindred word karmasal, (coccineus seu ver- miculatus) as an Armenian word. It is notorious that the in- sects in question have long been produced and employed for dying, both in Armenia and Persia ; and that they were there called kermes, may be proved among other testimonies by the following extract from Sir John Chardin's account of Persia, published in Harris's Collection of Voyages, where, treating of Media, he says, " they gather cochineal, though in no great quantify, nor for any longer time than eight days in summer, when the sun is in Leo ; for before that time the people say it doth not come to maturity ; and after it, the ivorm from which they draw the cochineal, makes a hole in the leaf in which it grows, and is lost. The Persians (he adds) call cochineal kermes from kerm, which signifies a worm, because it is ex- tracted out of worms." It can hardly be necessary to remark, that the term cochineal is here improperly used, and that nothing more is meant by it, than the colouring matter of the kermes 5 PERMANENT COLOURS. 399 (as has been mentioned by Dioscorides., Dodo- ncus, and others) kermes was an indigenous production, and had for many ages been em- ployed in dying. By thus adopting the name of kermes, the Italians afterwards produced from it the words chermisi, cremesino, and chermesino ; and the French those of carmesin, carmine, and cramoisi ; whence the English word crimson was borrowed. The origin or derivation of the name escar- latuni, searletum, scarlata, squarlata, scarlatina, or scharlaiica, from which the French escarlate or ecarlatc, and the English scarlet have been formed, is more uncertain : Pczronius thought it of Celtic extraction ; -and that it signified galaticus rubor, (see Antiq. Celt. p. 69.) But ac- cording to Beckman, Stiler asserts that scar lack is a German word, compounded of sckor, fire, and lacken, cloth ; and consequently that it sig- nifies fire-coloure d cloth : while Reiske, on the contrary, derives the words in question from the Arabic scharal meaning, the kermes dye. It may be observed in favour of Stilers asser- tion, that the kermes red has in different ages been compared to the colour of fire, I have seen the words " arcknti radiabat Scipio cocco.'' which continues, according to the best information that I can procure, to be employed in a great part of India, as well as Persia, particularly for the dying of silk. ^MM 400 PHILOSOPHY OF in some of the Latin classics, though I cannot recollect which. And Bischoff, on the authority of Muratori,* mentions an old charter or con- tract passed in the year 1 194, between the cities of Bologna and Ferrara, by which a duty was to be levied in the former of these cities, upon the grana de Brasile, meaning kermes, (and upon indigo) ; and he adds that these Brasilian grains, and also Brasil wood, are mentioned in other old charters, particularly one dated in 1193, and another in 1806, under the name of Brcucilis; and he concludes, with great probability, that this, and the word brasilis, were derived from bragio a burning coal ; in the French braise: and we shall accordingly find hereafter, that red dying- woods, similar to that now called Brasil wood, were distinguished by that name, before any such wood was known or suspected to be pro- duced in that part of America now called Bra- sil ; and that this name was given to that country many years afterwards, when the wood came to be thence imported ; and consequently that the country obtained the name from the wood, and not the wood from the country. At what time the words from which our scarlet was derived were first used, cannot, I believe, now be accurately ascertained ; the * Dissert, de Mercatibus et Mercatura saeculorum radium, torn, ii — Antiquitat. diss, xxx, p. 893. PERMANENT COLOURS. 401 most early employment of them, of which I have found an instance, is that which Beckman has quoted from the Historia Gelrica Pontani, (Hordervici 163Q,) in which, about the year ]050, the emperor Henry III. conferred upon the Count of Cleves, the Burgraviate of Nime- guen, on the condition of his delivering to him annually three pieces of scarlet cloth, made of English wool (" ties paunos scarlatinas angllca- flos") Beckman also refers to a document in Lu- nig's Codex Diplom. Germanise, ii. p. 1739, by which the emperor Frederick, in 1217, confer- red on the Count of Gueldrcs, the hereditable jurisdiction of Nimeguen, on condition that he and his successors, " de eodem telonio, singulis annis ties pannos scarlacos bene rubeos anglicen- ses ardentis coloris assignare deberet." The selec- tion of English cloth, in these instances, de- monstrates the high estimation in which it was held even at those periods. Beckman also refers to " Gervasii Tilberiensis Otia Imperialia ad Otto- nem iv. Imperatorcm, iii. 55 ;" a work written in 121 J, in which the author alluding to the kermes says, " Vermiculus hie est, quo tinguntur pre- tiosissimi regum panni, sive serici, ut examiti, sive lanei, ut scharlata" And he then mentions ^t as wonderful that neither linen, nor any other vegetable substance, would permanently take this dye, " sed sola vestis quae ex vivo animan- teque, vel quo vis animato decerpitur." He d d 402 PHILOSOPHY OF afterwards mentions the shrub on which the kermes were round, and, like Dioscorides, com- pares the latter to peas, in regard to their shape and size ; adding, " cum enim tempus solstitii rcstivi advenerit, ex seipso vermiculos generat, et nisi coriis subtiliter consutis includerentur, omnes f afferent, aut in nihilum evanescerent. Hinc est quod vermiculus nominatur, propter dissolutionem quam in vermes facile facit, ex natura roris maialis, a quo generatur ; unde et illo tantum rnense colligitur." We see by the latter part of this extract, that the kermes were not at that time, as at present in Fiance and Spain, killed by being sprinkled with vine- gar and dried in the sun ; and therefore, to pre- vent their ultimate escape, they were secured by being put into leathern bottles. Besides these instances of the early mention of scarlet, it occurs in several books, written .in the thirteenth 1 century; such as the History of Spain, by Roderick archbishop of Toledo, (lib. vii, l), which was finished in 1243 ; and in some quoted by Vossius, " de vitiis sermon is, 4°.'- Others might be added to these, were they ne- cessary. At the periods when the terms escarlatum, &c. were thus employed, the art of dying purple from the murex and buccinum was lost in the western empire, ai.d the kermes dye, which in former limes had been almost as much esteemed, PERMANENT COLOURS. 403 was become pre-eminent and unrivalled ; and so it continued, until the introduction of cochineal, from America, (to be noticed in my next chap- ter) which has, in great degree, put an end to the useofkermes in Europe, though the acorn-bear- ing shrub, which the ancients called ilex, (and which, in the Linnfean system, is denominated quercus coccifera) still grows, and furnishes these insects, in all the countries mentioned as for- merly producing them ; and though the insects themselves continue to be employed in other parts of the world, and with great reason, for in truth they are capable, as my own experi- ments prove, of giving every colour which can be obtained from cochineal with equal beauty and vivacity, and perhaps with even greater permanency. The first volume of the Philosophical Trans- actions contains a paper, written by M. Verney, then of Montpellier, respecting the natural his- tory of the kermes ; and M. Reaumur afterwards described them very minutely in the fourth volume of his " Metnoires pour servir a l'His- toire des Insectes." But the most useful infor- mation on this subject seems to be that which M. Chaptal lately gave to M. Berthollet, and which he lias published in the second volume of his " Elemens de I'Art de laTeinture." By his account, the male insect passes from its vermi- cular state, through the usual forms, into that nd 2 404 PHILOSOPHY OF of a fly with four w ings ; though the femal? never acquires any wings, but fixes herself on a leaf of the oak, where, being impregnated by the male, her size gradually increases (as the eggs enlarge) to that of a juniper-berry, and she at the same time becomes of a reddish brown colour. When the eggs are on the point of hatching, the females should be collected, and exposed to the steam of vinegar, to kill them, and prevent their young from being brought forth ; and afterwards they should be dried, by being spread out on cloths, by which treatment they acquire the colour of red wine. M. Chaptal says, that a single person may collect from one to two pounds of kermes in a day. But it would require ten or twelve pounds to produce the effect of a single pound of cochineal ; and as the kermes, probably, could not be obtained in any quantity for less than half-a-crown the pound, the colour which the}' afford, would prove more costly than that of cochineal, at the price which the latter has commonly borne previous to the present war. Ilcllot tells us, chapter xii. that the red dra- peries of the figures exhibited in the ancient Brussels and other Flemish tapestries, were all dyed from kermes, and that this colour, which in many of them has subsisted more than 200 years, has lost but very little, if any, of its original vivacity : and Beckman represents this PERMANENT COLOURS. 405 as being true of some pieces of tapestry, which are believed to have been dyed with kermes as early as the twelfth century. The fine red or crimson colour of these tapestries, which was ori- ginally called simply scarlet, took the name of Venetian scarlet, after the cochineal scarlet upon a tin basis was discovered, because, as Hellot mentions, it continued to be extensively dyed at Venice, long after it had become unfashion- able in other parts of Europe; though it ap- pears, from my own particular experiments, that if the kermes, like the cochineal, had been em- ployed with a solution of tin by nitro-muriatiG acid (instead of alum), a colour might have been obtained, which it would have been difficult, if not impossible, to distinguish from the cochi- neal scarlet. To dye the Venetian scarlet, the w 7 ool, ac- cording to Hellot, was first boiled for half an hour in water, with about its weight of bran, tied up in a bag; it was then removed into another vessel, and boiled two hours in water acidulated by fermented bran liquor, with a fifth of its weight of Roman alum, and half as much red tartar; leaving the wool, after taking it out of this vessel, moistened with the same liquor, during six days; at the end of which, it was dyed in clean soft water, with powdered Jcermes, allowing twelve ounces of the latter for m m ■§■ 406 PHILOSOPHY OF each pound of wool, and even sixteen ounces, if the kermes had suffered by age.* When the very extraordinary effect of a solu- tion of tin, in giving- vivacity and lustre to the colour of cochineal, had been discovered, (as will be mentioned hereafter) it might have been expected^ that the influence of this mordant upon the kermes colour would have been tried, as a matter of course, but I cannot any where find that this was done ; and it was not until I had dyed broad-cloth in the way, and with the means commonly employed to produce the scarlet colour, substituting only kermes for cochineal, in the proportion of twelve ounces of the former for one of the latter, that I satisfied myself of the practicability of dying with the kermes a scarlet colour, in every respect, as beau- tiful and estimable as any which can be dyed * In a letter written by Mr. William Kirkpatrick to Dr. Anderson, lately Physician- General in the service of the East- India Company, and dated Hyderabad, June 14th, 1/Q6, I find the following passage, viz. " The silk-dyers at this place do not know how, I believe, to produce a scarlet. To dye a prime crimson, they employ, to one seer of silk (fresh and white) one quarter seer of kermes, one quarter seer of alum, and one quarter seer of flowers of piste h (pistachio), which I take to stand in place of the gall. The enclosed is a specimen of their prime crimson." If this account of proportions be accurate, the kermes of India must yield more than twice as much colour as that of Europe. PERMANENT COLOURS. 40; with cochineal ; and, consequently, that if the mordant from tin had been properly employed with the kermes, there could have been no rea- sonable motive for giving a preference to cochineal, unless it was found to be ultimately cheaper than the kermes, by reason of the much greater proportion of colouring matter afforded by it. Cotton being topically impregnated with the acetate of alumine, as for calico-printing, and one-half of it being dyed with kermes, it took a full bright crimson, as the other did at the same time with cochineal; and the colours so dyed, (which in appearance were exactly simi- lar) being washed and exposed to the sun and air, manifested a considerable degree of perma- nency, though not sufficient to make it proper to employ them in this way, without an addition of madder ; the yellowish red colour of which is greatly improved by the bright crimson of either of these insects. I have thought, in this and other experiments, that the colour of the kermes was a little more durable than that of the cochineal, not from a difference in the co- louring matters of the insects, but from the astringent vegetable matter, or juice of the oak, which always accompanies the kermes. Subsequently to my former edition, I pro- cured a very sufficient supply of kermes from the South of France, and have tried them with 408 PHILOSOPHY OF nearly all the metallic and earthy bases or mor- dants, and always with very nearly the same re- sults as were obtained with the like bases or mor- dants from cochineal, and of which an account will be given hereafter ; and I conclude, therefore, that the animal part of the colour of the kermes is exactly similar to the colour of cochineal. Art. II. Coccus Polonicus, This is a small round insect, in many respects similar to the kermes, and employed for nearly the same purposes, until the introduction of cochineal caused the use of it to be abandoned, at least in the greater part of Europe. It was mostly collected in the Ukraine, and other pro- vinces of Poland, (under the name of Czerwiec) and also in the great duchy of Lithuania, from the roots of the German knotgrass, or perennial knawel (scleranthus pcrennis, Linn.). The male only, by a transformation similar to that of the male kermes, becomes a fly, though with but two wings, which are white, edged with red. The females being impregnated by the male, enlarge their size, and become ready to bring forth their young soon after the summer solstice, at which time they abound most in a crimson juice, which even now is much es- teemed and employed by the Turks and Arme- nians for d) irig wool, silk, and hair, and also to stain the nails of women's fingers. Wool and PERMANENT COLOURS. 409 silk were prepared to receive this dye with the same mordant (of alum and tartar) as that used for the kermes. Several writers have mentioned the coccus polonicus (sometimes called the cochineal of the north) : hut the hest account of it seems to be that given by Breynius in the Act. Natur. Curiosor. of the year 1733. There is also an account of it in the Phil. Trans, for I764, p. 9h Some writers have imagined, that the Latin, Italian, and French words signifying crimson, were more particularly applied to the colour dyed from the coccus polonicus ; but I do not find sufficient reason for adopting that opinion. Very similar to the coccus polonicus is an insect, which in many parts of Europe wa$ formerly collected from the roots of the Burner, (poterium sangui soiba, Linn.); and which was used, particularly by the Moors, for dying wool and silk of a rose colour. Ray, in describing this plant, says, " IIujus radicis adnascitur qui- busdam in locis granum rubram, quo utuntur tinctores ad eolorem carmesinum, unde sunt qui pro cocco habent, et coccum radicum appel- lant," &c. Hist. Plantar. 401. The coccus uvse ursi, Linn., is another insect of the same order, and very much resembling the coccus polonicus, both in its properties and form, excepting the circumstance of its being nearly twice as large. It affords a crimson dye with alum, but is now seldom employed. 410 PHILOSOPHY OF CHAP. III. Of the Natural History of Cochineal, " Our vallics yield not, or but sparing yield " The dyers' gay materials. Only weld, " Or root of madder, here, or purple w»ad, " By which onr naked ancestors obscur'd a Their hardy limbs, inwrought with mystic forms, ° Like Egypt's obelisks." Dyer. The cochineal, or coccus cacti of Linnasus, is arranged among the "Insecta" of the fifth class of that great naturalist; and in the second order, comprehending the "Hemiptera," (half- winged insects, &c.) The body of the male is slender, of a red colour, covered by two wings, spread horizontally, and crossing each other a little on the back, and enabling him to fly, or rather flutter. The head is distinct, but small, with two diverging slender antennas ; the abdo- men or tail is terminated by two small and very long diverging hairs ; lie has six feet, with which he sometimes jumps, like the lacca insect ; and hence Linnasus has applied the term " sana- toria," as one of his distinguishing characters. The male insects are but seldom found among the cochineal sent to Europe. The back of the female is hemispherical, and crossed by PERMANENT COLOURS. 4U numerous wrinkles ; she is of a dark reddish brown colour; her mouth is a small tubular projection from the thorax ; she is without wings, but has six legs ; these, however, only serve her to remove during a short interval im- mediately succeeding her birth; after which they become useless, and ceasing to grow, whilst the body enlarges greatly, they, with the proboscis and antenna?, remain so small as to be afterwards hardly perceptible, at least without a very minute inspection. This circum- stance probably occasioned, and certainly con- firmed, the belief which prevailed very generally in Europe, during a considerable number of years, that these insects were vegetable grains or seeds.* * Caneparius was deceived in this way. He had been in- formed, that the cochineal consisted of insects collected from plants of the cactus kind by the help of forceps, and smothered j but he considered this as fabulous, asserting that the cochineal, which he calls " kabasinii grana," if steeped in hot water, recovered their original form, which, adds he, is not that of any thing animalcular, but distinctly the figure of a seed or grain of some fruit. " Non est ullius ani- malunculi, at seminis sive grani fructus figuram refert. Quare hasc grana sunt ficus Indicae rubra et splendida ut sanguis." He had heard that the fruit of the cactus " Tunce," or Indian fig, was red, and that it tinged the urine of those eating it, of a blood colour, which encouraged him to conclude as he did, that cochineal must be the seeds " ipsius twice ;' — " pro colore, carlisino vulgo chremise conticiendo tinctoribus commodo." See Caneparius, De Atramentis, &c. Venice, 10*1 9. p. 21 \, 212. 412 PHILOSOPHY OF The cochineal is nourished, perhaps exclu- sively, by some of the different species of the cactus, or Indian fig, (called by some the prickly pear,) a genus of plants, of which twenty-eight several species have been described,, all originally found in America only; of very different formSj and producing fruits of various colours when ripe, according to the species on which they respectively grow ; as yellow, red, crimson, purple, violet, green, &c. Among these, the red or crimson-coloured fruits more especially contain a mucilaginous juice, which communicates the colour of the fruit in a high degree to the urine of those by wkom it is eaten. That species on which the domesticated cochineal has been commonly propagated, is denominated cactus cochenillifer or coccinilifer by Linnasus. But the insects live naturally, in their wild state at least, on some of the other species, particularly the cactus tuna, cactus opuntia, and cactus pereskia; all of which, as well as the cactus cochenillifer, belong to that section of cacti which Linnasus distinguishes as 4i opuntiae compressor, articulis proliferis," i. e. flattened or compressed with prolific articula- tions. The cactus cochenillifer, however, which the Mexican Spaniards call nopal, is alone cul- tivated for the purpose of feeding and breeding these insects ; partly because it is unarmed, o*; PERMANENT COLOURS. An without those offensive spines which beset most of the other species. The Spaniards, on their first arrival in Mexico, about the year I0I8, saw the cochineal employed, (as it appears to have been long- before,) by the native inhabitants of that coun* try, in colouring some parts of their habitat- ions, ornaments, &c. and in staining their cot- ton ; and being struck with its beautiful colour, some accounts of it were given to the Spanish ministry, who in the year 1523, (as Ilerrar;* informs us) ordered Cortes to take measures for multiplying this valuable commodity ;* but as the Spaniards then in America were careless of every thing but gold and silver, they left this to be clone by the natives, who, from the large supplies soon after sent to Europe, appear to have successfully employed themselves for that purpose. * Herrara does not use the name of cochineal, but that ofi grana, (as other Spanish writers have since done) j and he says, (Decade, iii. v. 3.) the Catholic King had been informed that these grana were abundant in that part of America, and that the sending them to Spain might furnish means for paying th* sontributions, &c : — they were probably then supposed to resem- ble kermes. I have not been able to ascertain the origin of th« term cochineal, or coccinilla, nor the time when it was first applied to these insects : perhaps, as they were smaller than th« kermes, the term coccinilla was intended as a diminutive of coccum, as platina was of Plata, and both employed from simi- lar motives ; perhaps, also, it may have been erroneously sup- posed to belong to the genus coccinilla, or lady-bird. 414 PHILOSOPHY OF It is remarkable, that though Acosta had stated the cochineal to be an insect, as early as 15:30, and though Herrara and Hernandez did the same afterwards, these opinions were gene- rally overlooked or disregarded, and the people of Europe were for many years induced to believe, that this insect was a vegetable grain or seed, as I lately mentioned; a contrary opinion was, indeed, given by the anonymous author of a paper, in the third volume of the Philosophical Transactions, (printed in the year 1668,) in which he supposes cochineal to be an insect, " en- gendered" by the fruit of the prickly pear; and being a believer of equivocal generation, he proposes to employ fermentation as a means of engendering and multiplying these insects more copiously. In the year 1672, a paper written by Lister, was published in the seventh volume of the Phi- losophical Transactions, concerning the kermes, in which he " conjectures cochineal may be a sort of kermes." And the seventeenth volume of the Transactions, published in 1691, contains some observations concerning the making of cochineal according to a relation had from an old Spaniard at Jamaica, who says, "Cochineal is the same which we call lady-bird, alias cow-lady,* * The lady-bird, or cow-lady, has long been distinguished by the generic name of coccinella; a fact which may have occa- PERMANENT COLOURS. 415 which at first appears like a small blister, or little knob upon the leaves of the shrub on which they breed, and which afterwards, by the heat of the sun, becomes a live insect as above, or a small grub." Early in \693, Father Plumier wrote and subscribed a declaration, which he delivered to Pomet, affirming cochineal to be an insect living on the opuntia or Indian fig, and that he had seen it in the island of St. Domingo ; and De Laet had some little time before described it as feeding on the tuna. Pomet, however, misled by the prevailing opinion on this subject, as well as by several letters which about that time were sent to him from St. Domingo by F. Rous- seau, adopted the fallacious accounts of this letter-writer, (who promised to send over to France some of the very plants whose seeds, as he asserted, afforded the true cochineal,) and described this drug as the seed of a plant, two or three feet high, bearing pods of a conical form, in which the cochineal grew naturally. (See Hist. Gen. des Drogues, &c.) But, groundless as this account was in reality, it obtained so much credit, that no longer than sioned several mistakes. It seems to have misled Professor Fischer, when, in 1758, he proposed to propagate the lady bird or fly, by placing it on the kermes oak, and the perennial knawel, in order to produce cochineal in Europe. 1 ^B| BMW 4IG PHILOSOPHY OF four years since, a very eminent dyer of this metropolis seriously told me, that having bought a large parcel of cochineal, he actually found among it one of these conical pods, containing cochineal naturally attached to the inside of the pods. Lewenhoek, however, by his glasses plainly -saw, that the cochineal was an insect with six legs ; and in a letter, read at the Royal Society the 21st of March, 1704, and published in the xxivth volume of the Transactions, he posi- tively contradicted all those who had represented it as a vegetable grain ; and declared that, by dissections, he had invariably found eggs, or animaleula, in the supposed grains, and often to the amount of two hundred in each. He also represents these insects as "not produced from worms," but as "^at once bringing forth their like." About the year 1730, Dr. Rutty, then Secre- tary of the Royal Society, published a Natural History of Cochineal, (in the xxxvith volume of the Transactions,) from a work on this sub- ject by Melchior de la Ruuscher, of Amsterdam, who had procured from Antiquera, in New Spain, the depositions of eight persons, who had been actually employed for many years in the breed- ing and man igement of cochineal, and who swore that they were small living animals with " a beak, eyes, feet," &c. and the originals of PERMANENT COLOURS. 417 these depositions, notarially authenticated, were "deposited in the archives of the Royal Society.* Not long after this, Reaumur, in his Hist, des Insectes, and Dr. Crown, in his History of Jamaica, described the female cochineal with sufficient accuracy ; as did Linnaeus some time after, from some which had been sent to him by Rolander from Surinam, in the year ]756;{ though neither of these naturalists had ever seen the male cochineal. About the beginning of the year 1757, the late John Ellis, Esq. F. R. S. hearing that the cochineal insect bred in great abundance on the cactus opuntia, in South Carolina and Georgia, wrote to Dr. Alexander Garden, of Chaiicstown, * These depositions were juridically taken in October, 1725, to decide a wager on this subject, which wager is said to have amounted to the whole fortune of the loser, though the greater part of it was afterwards generously restored, after having been paid. De la Ruuscher's publication was intitled, " Naturlyke historie van de couchenille, beweezen met authentique docu- menten j" printed at Amsterdam, by Hermanus Uytwerf, 1729. f Rolander had been one of Linnaeus's pupils, and having sent to the latter a cactus, stocked with the wild cochineal insects, (there being no other at Surinam) the plant was brought to Upsal whilst the Professor was delivering a lecture, and when he afterwards inquired for it, the gardener told him, he just cleaned away the vermin, which he supposed the cochineal to be, and had planted it. And as none of the insects could be found alive, Linnaeus's description must have been made from, those which were dead. £ e m fSSSSBm 418 PHILOSOPHY OF South Carolina, for some of the joints of tljat plant, with the insects thereon, which were accordingly sent the latter end of that year, and laid before the Ro}-al Society. " These specimens (says Mr. Ellis) were full of the nests of this insect, in which it appeared in its various states, from the most minute, when it walks about, to the state when it becomes fixed and wrapt up in a fine web, which it spins about itself. " In order to find out the male fly, (conti- nues he,) I examined all the webs in these specimens, besides a large parcel which the Doctor had sent me picked off from the plants in Carolina, and at last discovered three or four minute dead flies with white wings. These I moistened in weak spirit of wine, and examining them in the microscope, I disco- vered their bodies to be of a bright red colour, which convinced me of their being the true male insect. To be confirmed in my opinion, I immediately communicated my discovery to Dr. Garden, which I accompanied with an ^xact microscopical drawing, and desired lie would send me some account of their economy, with some male insects of his own collect- ing ; which he did, in the spring of the year 1762, accompanied with the following observa- tions In August \159t (says Dr. Garden), I PERMANENT COLOURS. 4VJ catchcd a male cochineal fly, and examined it in your aquatic microscope. It is seldom a male is met with. I imagine there may be one hundred and fifty or two hundred females for one male. The male is a very active crea- ture, and well made, but slender in compa- rison of the females, who are much larger and more shapeless, and seemingly lazy, torpid, and inactive. They appear generally so over- grown, that their eyes and mouth are quite sunk in their rugse or wrinkles ; nay, their antennas and legs are almost covered by them, and are so impeded in their motions from these swellings about the insertions of their legs, that they can scarce move then?, much less move themselves. " The male's head is very distinct from the neck : the neck is much smaller than the head, and much more so than the body. The thorax is elliptical, and something larger than the head and neck together, and flattish under- neath ; from the front there arise two anten- nae, (much longer than those of the females), which the insect moves every way very briskly. These antennae are all jointed, and from every joint there come out four short sette, placed two on each side. (t It has three jointed legs on each side, and moves very briskly and with great speed. ■ e e 3 VH M 420 PHILOSOPHY OF From the extremity of the tail, there arise tw9 long seta? or hairs, four or five times the length of the insect. They diverge as they lengthen, are very slender, and of a pure snow-white colour. It has two wings, which take their rise from the hack part of their shoulders or thorax, and lie down horizontally, like the wings of the common fly, when the insect is walking. They are oblong, rounded at the extremity, and become suddenly small near the point of insertion. They are much longer than the body, and have two long nerves ; one runs from the basis of the wing along the external margin, and arches to meet a slender one that runs along the under and inner edge. They are quite thin, slender, transparent, and of a snowy whiteness. The body of the male is of a lighter red than the body of the female, and not near so large."* To Dr. Garden's description, Mr. Ellis, in * Justice to Mr. Catesby, requires mc to mention that he had some >cars before published the following statement i:i the Introduction to the first volume of his Natural History of Carolina., kc. viz. " In South Carolina grows a kind of Opuntia, which are frequently 3 or 4 feet high, from which I have often picked cochineal in small quantities. Both plants and insects were much smaller than those of Mexico j but the latter (i. e. the insects) were in colour and appearance the MfflH." PERMANENT COLOURS. 421 an account of the male and female cochineal in- sects, accompanied with drawings, &c. (in the fifty-second volume of the Philosophical Trans- actions,) adds, that the female has a remarkable proboscis, or awl-shaped papilla, arising in the midst of the breast, which Linnaeus calls the rostrum, and thinks it the mouth: " if so, (says Mr. Ellis,) besides the office of supplying it with nourishment during the time of its mo- ving about, it is the tube through which the fine double filament proceeds, with which it forms its delicate web, in order to accommo- date itself in its torpid state, during its preg- nancy, till the young ones creep out of its body, shift for themselves, and form a new ge- neration. " In this torpid state the legs and antennas grow no more, but the animal swells up to an enormous size, in proportion to its minute creeping state. The legs, antenna?, and pro- boscis, arc so small with respect to the rest of the body, that they cannot be easily discovered, without very good eyes or magnifying-glasses, so that to an indifferent eye it looks full as much like a berry as an animal. " As soon as the female is delivered of its numerous progeny, it becomes a mere husk and dies ; so that great care is taken in Mexico, where it is principally collected, tp kill the old ones while big with young, to prevent the I® 422 PHILOSOPHY OF young ones escaping into life, and depriving them of that beautiful scarlet dye, so much es- teemed by all the world." I ought to have sooner mentioned that there are two sorts or varieties of cochineal : the best or domesticated, which the Spaniards de- nominate grana jina, or fine grain ; and the wild, which they call grana sylvestra. The former is nearly twice as large as the latter; pro- bably because its size has been improved by the favourable effects of human care, and of a more copious or suitable nourishment, derived solely from the cactus cochenillifer, during many generations. But it is only from the wild cochi- neal, living naturally on some of the opuntia, in different parts of America, that the descriptions of Brown, Linnaeus, and Ellis, were taken. It must also be observed, that the grana sylvestra are not only smaller than the others, but that their bodies are covered by very fine white downy filaments, which they spin to defend themselves against cold, rain, &c. in their wild state ; but which adding to their weight, whilst it yields no colour, contributes with other causes to render them less valuable. In the month of January 1777, Mons. Thiery de Menonville left Port-au-Prince, in the island of St. Domingo, for the purpose of procuring some of the living cochineal insects in Mexico, and bringing them away, to be afterwards PERMANENT COLOURS. 425 propagated in the French West-India islands: an enterprize, for the expence of which four thou- sand livres had been allotted by the French go- vernment. He proceeded by the H a van n ah to La Vera Cruz, and, was there informed that the finest cochineal insects were produced at Guax- aca, distant about seventy leagues. Pretending ill health, he obtained permission to use the baths of the river Magdalena; but instead of going thither, he proceeded through various difficulties and dangers, as fast as possible, to Guaxaca, where, after making his observations, and obtaining the requisite informations, he affected to believe that the cochineal insects were highly useful in composing an ointment for his pretended disorder (the gout), and there- fore purchased a quantity of nopals, covered Avith these insects, of the fine or domestic breed, and putting them into boxes with other plants, for their better concealment, he found means to get them away as botanic trifles, unworthy of notice, notwithstanding the prohibitions by which the Spanish government had endea- voured to hinder their exportation ; and being afterwards driven by a violent storm into the bay of Campeachy, he there found and added to his collection a living cactus, of a species which w r as capable of nourishing the fine do- mesticated cochineal ; after which, departing for St. Domingo, he arrived safe, with his ^^^^^^^p 424 PHILOSOPHY OF acquisitions, on the 25th of September, (in the same year,) at Port-au Prince, where he began immediately to form a plantation of nopals, and to take steps for propagating the two sorts or varieties of cochineal, I mean the domesticated or fine, and the sylvestra or wild; which last he found at St. Domingo, soon after his return, living naturally on the cactus pereskia. But unfortunately for this establishment, he died in the year 1780, through disappointment and vexation, at seeing his patriotic endeavours so little assisted, and his services so sparingly rewarded by the government. Mr. Thiery de Menonville's labours being thus terminated, the Royal Society of Arts and Sciences, at Cape Francois, having collected his papers, composed from them a treatise on the cultivation of the nopals, and the breeding of cochineal, &c. of which M. Berthollet has given a short extract in the fifth volume of the Annales de Chymie, together with an account of his own experi- ments for ascertaining the effects of the grana sylvestra, produced at St. Domingo, compared with those from Mexico, in dying.* From the observations of Mr. Thiery de Me- * The original'publication (from which my account was •written,) is entitled, " Traite de la Culture du Nopal ct de J'Education de la Cochenille," 8vo. printed au Cape Fran- cois, 1787. PERMANENT COLOURS. 42» nonville, it appears that there are two varieties of the nopal, or cactus cochenillifer, growing in Mexico, one called the true nopal of the Garden of Mexico, and the other the Cnstilian nopal, a name given to the last of these varie- ties on account of its singular beauty. It ap- pears also that the wild cochineal, or grana syl- vestra, when reared upon either of these varie- ties of the nopal, become almost as large as the fine or domesticated sort, and lose the great- est part of those fine downy filaments with which they are naturally covered, and which contribute to render them less valuable than the latter. But besides the advantage of affording the most suitable nourishment to cochineal, the no- pals have another of very great importance, where these insects are to be raised as objects of commerce ; which is, that they are not beset with thorns or prickles, like most of the cacti, and particularly the opuntia, tuna, and pereskia, which, by this circumstance, render the insects nourished upon them, almost inaccessible to any who might wish to collect them : whilst the true nopal, and that of Castile, have none but soft inoffensive thorns, and the nourishment which they afford is at the same time so pecu- liarly well suited to the cochineal, and especially to the fine or domesticated sort, that these last, though they can subsist on some, will prosper on 426 PHILOSOPHY OF no other species of cactus ; and indeed the wild sort, though found naturally upon several other species of opuntia, are at present raised chiefly on the nopals in Mexico. The young insects, whilst contained within the mother, appear to be all connected one after the other by an umbi- lical cord to a common placenta, and in this order they are in due time brought forth as liv- ing animals, after breaking the membrane, in which they were at first probably contained as eggs. Being thus brought forth, they re- main in a cluster under the mother's belly for two or three days, until disengaged from the umbilical cord ; after which the females, for the only time of their lives, exercise their loco-motive faculties, by creeping to proper situations on the plant ; and in doing this they are led by a wise instinct, to prefer the under- sides of the different branches or articula- tions, (as being most defended from wind and rain,) where each attaches herself, by inserting her little tubular proboscis or mouth into the bark, and thus remains fixed to the end of life. By this insertion the female draws out for her nourishment the colourless mucilaginous juice of the nopal, and soon becomes covered with a fine adhesive downy substance. The male ac- quires a similar covering, but quits it at the end of a month, and in the shape of a little scarlet fly, jumps and flutters about for the purpose of PERMANENT COLOURS. 427 copulation; and having thereby secured a future progeny, he dies almost immediately after. But the female having other duties to perform, out- lives the male another month ; at the end of which she is ready to hring forth her young, and this is the precise time for gathering those which are not wanted for breeding ; which is done by pressing the dull blade of a knife be- tween the under surface of a branch of the nopal, and the clusters of insects attached to it, when the latter, being thereby separated, fall upon cloths previously spread on the ground to re- ceive them ; and a sufficient quantity being thus collected, they are dipped (enclosed in a linen cloth or bag) into boiling water, and suffered to remain in it so long as is necessary for killing them, but no longer, lest the water should extract some of their colour. This being done, they are thoroughly dried, by spreading and exposing them to the rays of the sun, by which they shrink so as generally to lose about two- thirds of their former weight. This, which has been found to be the best method of drying the cochineal, is now generally practised, though others were formerly in use ; such as ovens, flat baking stones heated, &c. Mr. Thiery de Menonville describes the male of the domesticated or fine cochineal as per- fectly similar to that of the wild in every re- spect, excepting its size ; nor does there appear 428 PHILOSOPHY OF to be any considerable difference between the females of these two varieties. The domesticated female, instead of that downy covering, which enables the wild to bear inclement seasons, is only covered by a fine white powder or farina, serving in some degree as a defence against rain and cold, but not enough to enable her to re- main abroad like the wild insects during the rainy seasons, which occur twice in every year. When these approach, the domesticated insects are all gathered and dried, excepting only those intended for breeding a future stock ; which are preserved, by either removing the nopals in- habited by them, into situations where they are secured from wind and rain, or by raising frames over them, and covering them with thatch or matting, until the return of favourable ■weather ; but the wild insects, being more hardy, as well as more prolific, when once placed upon the nopals, would not only per- petuate, but multiply themselves, without any farther care, to such a degree as to exhaust and destroy the plants, were they not all col- lected at the end of every two months, and the plants perfectly cleansed (by wiping them with wetted cloths) from the down and other animal impurities left on their branches. The nopals become fit to nourish the cochineal at the end of eighteen months from the time they were planted. The quantity of fine or domesticated PERMANENT COLOURS. 429 cochineal, which a single nopal can nourish, usually weighs a third more than it could nou- rish of the wild. These last have also the disadvantage of selling for a much less price ; but in return, they are gathered six times in each year, whilst the fine yield but three crops in the same space, their propagation being wholly suspended during the rainy seasons. In Mexico it is thought necessary to keep the two sorts or varieties of cochineal separated, at the distance of about one hundred perches from each other, lest the males of the wild, by impregnating the females of the other sort, should occasion a degeneration of the latter ; a circumstance which seems to indicate that both sorts originated from the same stock, and that the domesticated is only an amelioration of the wild cochineal, through the favourable effects of a more suitable nourishment, and of warm covering ; and this is rendered the more proba- ble, by Mr. Thiery de Menonville's observation, that the former are never found in the fields or forests of Mexico, nor indeed any where but in the gardens and plantations of those em- ployed in rearing them. But if the present size, appearance, and habits, of the domestic cochineal, were those which naturally belong to the insect, it might be supposed capable of maintaining an independent existence, remote from the dwellings, and without the help of mm w$$M 430 PHILOSOPHY OF mankind, as it must have done before its proper- ties were so well known as to render it an objeet of human care and proteetion ; and in that case, some of this sort of cochineal doubt- less would have continued to subsist in their natural state, since the whole of a race, com- posed of so many minute individuals, could not have been taken and brought under the protec- tion and dominion of man. Nor is it easy to explain why none of them ever are found in a wild state, but by supposing them to have been rendered effeminate by luxurious food, and by protection from inclement weather ; and that, consequently, they have been enabled to lay aside their natural downy clothing, as sheep lay aside their wool, w"hen, after being removed to warm climates, they find it no longer neces- sary ; and that their natural habits and means of self-preservation being lost, they are rendered incapable of subsisting without a continuance of the same fostering care which first occa- sioned their effeminacy ; or, if they ever do find means to subsist without it, they do so only by regaining their natural downy covering, and by returning again to their primitive habits, so as not to be any longer distinguishable from those who were never out of the wild state. After the death of Mr. Thiery de Menon- Ville, the stock of fine or domesticated cochi- neal, which he had multiplied in the garden at PERMANENT COLOURS. 431 Port-au-Prince, was suffered to perish by neg- lect; but the hardier wild sort, having found means to subsist, though neglected, was af- terwards taken under the care of Mr. Bru- ley, (substitute of the attorney-general of that province,) who, from the remains of Mr. de Menonville's establishment, formed a plantation for propagating and multiplying these insects, of which he sent a considerable quantity, in the year 1787, to the minister of the French ma- rine at Paris, at whose request the Royal Aca- demy of Sciences commissioned M. Berthol- let, and three others of its members, to cause proper experiments to be made therewith, which they accordingly did, under their own inspection, at the celebrated establishment of the Gobelins near Paris ; and from these experiments it appeared, that the grana syl- vestra of St. Domingo afforded colours by dying, exactly similar to those of the Spanish fine cochineal, allowing only after the rate of twelve ounces of the former for five of the lat- ter. Mr. Bruley some time after sent to France a second parcel of the same cochineal, produced from his plantation in the year 1788; and this being tried by the same commissaries of the Royal Academy, though in different ways, pro- duced nearly the same effects. Very considerable differences of external co- lour or appearance occur in different parcels of ■ 432 PHILOSOPHY OF the fine cochineal; probably, because the white farinaceous powder, with which these insects are naturally covered, is more or less washed off by the hot water in which they are killed by immersion, as well as by other circum- stances which occur in the drying and packing. When this powder has been entirely removed, the insects appear of a chocolate colour, in- clining a little to the purple, and they are then called renigr'ida. Generally, however, so much of the white powder remains, especially in the little furrows which cross the insect's back, as occasions a greyish appearance, called jaspeada ; and sometimes, indeed, this powder so perfectly covers the cochineal, as to render them all over white. This I remember to have been particu- larly the case with a parcel which a friend of mine had purchased, and which was refused by several dyers to whom it had been sent, from a persuasion of its having been fraudulently co- vered by white lead, or some other metallic calx: intermixed with it, to increase the weight; and one very eminent dyer alleged, that he had formerly seen and tried a similar parcel, and that the white powder had been found to con- sist principally of a preparation of mercury. That I might be enabled to ascertain whether an opinion so unlikely had any foundation, ray friend caused several ounces of this powder to jbe separated from the insects by sifting; aael PERMANENT COLOURS. 433 having tried it sufficiently, I found it to be en- tirely of an animal nature, and apparently no- thing but the farina which naturally covers these insects. It even yielded a considerable portion of the true cochineal colour, and dyed good scarlets in the usual way, \ though it probably was assisted by some of the limbs or other parts of the bodies of the insects, sepa- rated by rubbing in the sieve : but I am persuaded that a part of the colour in question naturally existed in the farina or white powder itself; and if this be the case, it would be highly advantageous to contrive means for killing the cochineal, without washing off any part of the powder in question, which might, I think, be done by putting them into tinned vessels, made so as to shut closely, which might be plunged into boiling water, and withdrawn at a proper time, without letting a single drop of water come into contact with the insects, or car- rying off any of the powder in question. And perhaps this method might be used with advan- tage, even if it should be found that no colour- ing matter resides in the white powder, since it is difficult to conceive that the cochineal can be plunged into boiling water, so as to wash away the powder entirely, (as is frequently done,) without a loss of some part of the colouring matter contained in the bodies of the insects themselves. In general, therefore, it will be Ff VHH 43* PHILOSOPHY OF safest to choose that cochineal which is large, plump, clean, dry, and of a silver white colour on the surface. The true original grana sylvestra seem to have been very different from the composition which is at present sold under that denomination in this kingdom, and which has tiie appearance of a dry powder, with many small lumps or fragments of something which had been previ- ously formed into a cake or dried uniform mass. It affords, though in an inferior degree, some of the same sort of colour as cochineal, but in a small proportion ; six pounds being necessary, according to my experiments, -to dye as much cloth as one pound of the fine cochineal ; whereas the true grana sylvestra are represented as yielding at least half as much as the fine, and they sell for at least half the price in some parts of Europe, whilst here, the substance so called, and which has not the least appearance of any insect, sells at present for less than an eighth of the price of line cochineal. Probably it is composed of the white downy substance winch the wild insects are represented as leaving in great abundance on the nopals, and of other excrementitious matters deposited by them, joined to fragments, broken limbs, and dust, o! trie insects themselves, and perhaps with an addition of some vegetable matters, all beat up into one uniform mass, Something of this sort PERMANENT COLOURS. 435 was formerly practised even with the true cochi- neal, according to Dr. Brown, who says, " The cochineal insects used to be prepared by pound- ing them, and steeping the pulp in the decoction of the texuatla, (a species of melastoma, as he supposes,) or that of some other plants, which they observed to heighten the colour. This (continues Dr. Brown) was left to settle at lei- sure, and afterwards made into cakes and dried for the market." Hernandez also mentions that in his time cakes were made from cochineal in Mexico. Probably the true grana sylvestra, mixed with fragments of the true cochineal, compose what is sold in this country under the name of Granillo, which appears, as the name indeed imports, to consist chiefly of insects somewhat smaller than those composing the fine cochineal, and therefore, in that respect, answers to the best authenticated descriptions of the wild cochineal. It had been generally believed that the cochi- neal derived its colour from the red or crimson fruit of the nopals, and other species of opun- tiae ; and I was formerly induced by this opi- nion to make various trials with the red fruit of the cactus opuntia for dying, instead of cochineal. They all, indeed, proved unsuccess- ful ; but I was disposed to attribute my failure to the want of that kind of animalization, which the vegetable red colouring matter was Ff2 SBHBHBi 436 PHILOSOPHY OF supposed to receive, when eaten and assimilated by the insect : and I thought it probable, that other vegetable colouring matters might be equally improved in the same way, and that perhaps, instead of insects, it might be advanta- geous to employ larger animals for this purpose.* It is, however, now certain, from the observa- tions of Mr. Thiery de Menonville, and from other well-attested relations, that the cochineal insects do not feed on the red fruit of the cactus, but upon its branches or articulations, to which they adhere, and which contain nothing like a red juice ; and that they sometimes live, propa- gate, and preserve their colour on those species of cactns which do not bear red-coloured fruits : consequently, the colour of these insects does * Dr. Garden relates, that a negro woman in South Carolina, who then gave suck, having eaten six of the red fruit of the prickly pear, (cactus opuntia) and some of her milk being col- lected, and left until the cream had separated, this last was found to be of a reddish colour, considerably weaker, indeed, than the lively red which the urine was found to acquire by the same fruit. See Philosoph. Trans, vol. 50, p. 269. In the third vol. of the same Transactions, mention is made of a berry growing in Bermudas, and called the " Summer Island Red- weed, which berry is as red as the prickly pear, and giving much the like tincture ; out of which berry cometh out first worms, which afterwards turn into flies, (somewhat bigger than the cochineal fly,) feeding on the same berry, in which there hath been found a colour no whit inferior to the cochineal fly." PERMANENT COLOURS. 437 not result from that of their food, but from their peculiar constitution and organization.* * Although the facts here stated were published more than 18 years ago, the error which they were intended to correct, not only subsists, but continues to be propagated by weighty authorities. M. Fabroni, who was lately mentioned at p. 289, asserts, (Ann. de Chimie, torn. xxv. p. 301) that the cochineal insect can with its proboscis extract from the nopal its juice, which afterwards communicates its fine red colour to the in- sect ; and this juice, he adds, " selon moi, est le meme que la nature nous presente a* nu dans les fruits vmrs de cette meme plante." Bouillon La Grange also endeavours to maintain the same error, in his Manuel de Chimie, torn. ii. p. 743, where he asserts that the cactus coccinilifer " communique son sue rouge i l'insecte, qui s'en nourrit." But a more important support has been given to this error by the author of a respectable botanical work, now publishing in Jamaica, under the title of Hortus Jamaicensis, in two volumes 4to. who not only adopts the error, but, to confirm it, has (vol. i. p. 412) adduced copious extracts from Mr. Long's History of Jamaica, (a work in great estimation) of which ex*tacts the following are a part, via. " This juice (of the fruit of the cactus) is the natural food f the cochineal insect, which owes to it the value and property it possesses, as a dye in some of our principal manufactures. The exuviaand animal salts of the insect are, from the minuteness of its parts, inseparable from the essential principles of the dye ; whence it follows, that such a heterogeneous mixture must ne- cessarily destroy the brilliancy of colour inherent to the juice of this fruit; and that the juice itself, which alone contains the dying principle, must, if unmixed and brought to consistence, yield a true perfect colour, lively and brilliant, as we find it in its natural state." te Upon this hypothesis, Mr. David Riz, an ingenious gen- 438 PHILOSOPHY OF The very great demand for cochineal, almost immediately after it had been made known in tleman of Kingston, in this island, proceeded in several experi- ments to obtain from the plant artificially, what nature accom- plished in the insect, and at length happily succeeded, by in- spissating the juice j but the means he used are not yet com- municated to the public. Encouraged by this discovery, he went to England with seventy-six processes, differently manu- factured, to try which would answer best as a substitute to the cochineal. After a great number of experiments, he found one process which communicated a crimson colour to silk and wool, superior to that given by cochineal ; trials of which were made before a number of the principal dyers in and about London, at the Museum of the Royal Society , invited therefor that purpose. He also found two other processes, which promised, with very little alteration in their manufactory, to afford the colour-making dyes of scarlet and purple. Upon a moderate calculation it was found, that his colour would go further than three times the quantity of cochineal, which he accounted for by remarking, that there is a great part of the insect, as its skin, &c. which affords no dye, but that the whole of his process was genuine colour, with little or no impurity." " Notwithstanding the advantages that might be derived to the nation from this gentleman's discovery, he met upon the whole with very little encouragement to prosecute his manufac- ture further." Long's History, &c. p. 731. Upon this statement I shall only observe, that if, in fact, Mr. Riz did, as is alleged, produce any substance or preparation capable of dying a good scarlet, and of producing as much co- lour as three times its weight of cochineal, he must have ob- tained it otherwise than from the cactus, and probably it must have been an extract of cochineal, like those preparations com- monly sold under the name of carmine, except that it may have contained none of the aluminous basis, or that of tin. For PERMANENT COLOURS. 43.9 Europe, caused a very rapid multiplication there- of in the Spanish American settlements. It appears from Acosta's statement, that so early as the year 1587, there came to Spain, by a single flota, no less than 5670 arobas of fine cochineal, which, at the rate of $5 lb. each, weighed 141,750 pounds; and the common annual im- portation, as stated some years since by the Abb6 Raynal, has amounted to 400O quintals, or 400,000ib. weight of the fine cochineal, 300 quintals of the grana sylvestra, 200 ditto of granillo, and 100 of cochineal dust, which were computed to have sold for a sum equi- what purpose such an imposition was practised, I am not bound to inquire. But certainly the red fruit of any and every species of cactus, is as incapable, as a cranberry, of affording a colouring matter similar to that of cochineal j and since it has become notorious that this insect does not meddle with the fruit, (the only part of the cactus which exhibits a red colour) the notion which I now combat, has been left without any foundation or probability. I have already stated that the co- louring matter of the kermes, is similar to that of cochineal, and yet no body has ever suspected the kermes to derive its colour from the leaves of the oak, on which it is produced, there being no red. juice in these leaves, nor indeed, in those parts of the cactus to which the cochineal insects attach them- selves exclusively. An error similar to the preceding, seems to have subsisted formerly in regard to the purple-giving murex, as mentioned by Aristotle (Hist. Animal, vi. cap. Ed. Scaliger,) who says that a sea-weed (Fucus) probably Orchella, having been cast on shore near the Hellespont, which yielded a purple colour, the neighbouring inhabitants concluded it to be the food of the purple shell-fish, m m 440 PHILOSOPHY OF valent to about nine millions of French iivres ; without reckoning considerable quantities sent directly from America to the Philippine islands, for supplying a considerable part of Asia. The European importations have, however, been considerably increased, during several of the last years.* Since, according to very good in- formation, which I have received, the quan- tities of fine cochineal brought to Spain in the years 1788, 1789, and 1790, amounted to eleven thousand bags, weighing 2001b. each, and making together 2, 200,0001b. weight ; and between the 1st of January 1791, and the 1st of October in the same year, the importations had exceeded 2000 bags. It must, however, be observed, that the im- portations during these years were somewhat greater than usual, because an advance in the price of cochineal in Europe had induced the holders of it in America to send their stocks more speedily to market, in order to avail them- selves of the higher prices ; and, from accurate calculations, I think it may be concluded, that the average quantity of fine cochineal annually consumed in Europe amounts to about three thousand bags, or 6\)0,0()()lb. weight, of which about 120O bags, or 240,0001b. weight, may be considered as the present annual consumption of Great Britain. A greater quantity comes in- * This was written in 1793. PERMANENT COLOURS. 441 deed into the kingdom, but the surplus is again exported to other countries. These 1200 bags may be supposed to cost 180,0001. sterling, va- lued at 15s. per lb. which has been about the average price for some years past.* According to Don Antonio Ulloa, the greatest quantities of cochineal are produced at Oaxaca, Tlascala, Chulula, Neuva Gallicia, and Chiapa, in New Spain, and at Hambatio, Loja, and Tucuman, in Peru. About six years ago, Dr. James Anderson, physician-general on the company's establishment at Madras, persuaded himself that he had found the true cochineal insects subsisting naturally on a species of salt grass in that part of India ; and some parcels of a dried insect, probably of the coccus kind, (but more like the kermes,) which he mistook for the true coccus cacti, were sent by him to this country ; of which I made several trials, at the request of a friend, (as others also did,) and found them to be neither of the same species, nor possessed in any de- gree of that particular colouring matter for which the cochineal insect is so highly valued; * Since the year in 1793, the price of cochineal has more than doubled ; it has continued during the last eight years at more than 30s. the pound, and has sometimes exceeded 50s. But this augmentation of price, or a change of fashion, seems to have considerably diminished the annual consumption of Great Britain, which may now be estimated at about 750 bags. 442 PHILOSOPHY OF though in their dried state they had nearly the same external appearance, excepting their size, which was considerably less than that of the true Mexican cochineal ; but upon rubbing them in a mortar, I soon perceived, that instead of breaking into a dry powder like cochineal, they could only be beat into a kind of unctuous paste ; nor would any degree of drying, short of combustion, overcome this unctuous quality, or render them capable of being rub- bed into the form of a powder; and in point of colour there was a more essential difference, since they produced nothing better than a cho- colate brown, by the means usually employed for dying scarlet with cochineal, nor indeed by any other means. This chocolate colour proved indeed sufficiently durable on wool ; but it may be dyed so cheaply by other matters, and indeed these insects yielded so little of it, that they never can be worth collecting as a dying drug.* It occurred to me, however, on this occasion, that though Dr. Anderson had failed in his ex- * The Company, in their letter of the 31st of July 1/87, to the government of Madras, were pleased, from very lau- dable motives, to direct, that every further pursuit respect- ing this species of insects " should be effectually discouraged," because " were it to fall into the hands of improper persons, it might be made use of to mix with and adulterate the real cochineal, to the great injury of the consumer, as it would most assuredly spoil the beauty of every scarlet done therewith." PERMANENT COLOURS. 443 pectation of finding the cochineal in a country where it probably never existed, (the genus of plants on which it is naturally fitted and destined to live having been originally produced only in America,) yet it would not be very difficult to convey both the insects, and the cactus coche- nilliter (their natural food and habitation) to the East Indies, and there propagate both, so as in a few years to obtain from thence ample sup- plies of a drug so highly important in a great manufacturing country, and for which nearly 200,0001. sterling are annually paid by this to the Spanish nation, especially as great advan- tages in this respect would result from the cheap- ness of labour and subsistence in the East In- dies ; and considering moreover how much the quality of the indigo of that country had been improved, and the quantity increased within a few years, through the measures taken so opportunely for these purposes by fhe East- India Company, at a time when the usual sup- plies of that article from other countries had been greatly diminished. Similar idea- ,on this subject occurred, or were suggested, to the Directors of the East-India Company, who, in the spring of the year 1/38, procured from his Majesty's botanic garden at Kew (through Sir J. Banks, i It. S.), some of the true nop - two oi which were sent out by the Bridgwater, during that SB SRS 444 PHILOSOPHY OF season, to Madras, and put under the care of Dr. Anderson, where they have since been mul- tiplied to several thousands,* and been trans- planted from thence to Bengal, and St. Helena, in order that a sufficient stock might be in rea- diness to receive any cochineal insects which should arrive ; a committee of the Directors having previously reported as " their opinion, that it be recommended to the Committee of Correspondence to take such measures as they shall judge best suited for procuring from Ame- rica a quantity of the cochineal insect, with a view to the introduction of the same upon the coast of Coromandel." Unfortunately, how- ever, it does not appear that any measures have yet been effectual in procuring the domesticated insect, or even the sylvestra, though this last exists in Jamaica, (as does the true nopal j) and in many other accessible parts of America, and probably in more than ordinary perfection in Brasil; at least I made trial about the year 1787 of some which had been sent from thence by * It has since been ascertained that these plants were not the true nopal, or cactus coccinillifer, but a different species, much less suited to the purpose for which they were intended. f The cactus coccinillifer, and the cactus Pereskia (or Spa- nish gooseberry), are both mentioned in a recent catalogue of the Hortus Eastensis, as growing in the botanical garden of the late Mr. East, at Jamaica j and others are said to be growing in Loogville Garden, in the same island. PERMANENT COLOURS. 445 the way of Lisbon, and which yielded full as much colour, and of as much beauty, as half its weight of the very best fine cochineal; and until this last can be obtained, would' it not be advisable to make trial of the other, which, by being properly nursed, and nourished upon the true nopals, might perhaps, in a little time, im- prove so as to supersede the necessity of seeking any farther?* * Subsequently to this suggestion, and as I believe in con- sequence of it, some of the Brasilian cochineal insects were carried to India by one of the Company's ships which had touched at that part of America, and some quantities of cochi- neal have been at different times imported to this country, which were derived from the Brasilian stock. I had collected authentic and valuable information on this subject, and had made experiments with the cochineal itself ; but the papers containing an account of them, and of the information so col- lected, have been unaccountably lost or purloined, with others, probably of more importance, and I dare not rely on my recol- lections so far as to enter upon any statement of their con- tents. 446 PHILOSOPHY OF CHAPTER IV. Of the Properties and Uses of Cochineal ; with an Account of new Observations and Experi- ments calculated to improve the Scarlet Dye. " Le travail a£te" n ien, le profit en soit au lecrenr." Jean Key. In the English translation of Clavigero's His- tory of Mexico, the ancient inhabitants of that country are said to have obtained a purple lour from cochineal. Probably, however, either the author or translator of that work, has mistaken purple for crimson ; this last being the natural colour of cochineal, and what it al- ways affords with the aluminous basis, which Clavigero, in another part of his history, says the Mexicans had been used to employ in early times ; though it certainly is difficult to under- stand how they could have become acquainted with it." This account moreover accords with that of Herrara, who, after mentioning the Tuna or Nopal of Tlaxcalla, says, " Optimum longk granum dat Tlaxcallum cujus indigent prestantissimam tincturam ex illo conficiunr, hoc modo, comminuunt & mace! ant in de- cocto aluminis, & ubi resederit, cogunt in ta- bellas, quas Hispani vocantgra/za en pan"* * Whilst alum was the only mordant employed with cochi- neal, these grain cakes made with a decoction of alum might answer very well, but not afterwards. PERMANENT COLOURS. 447 There is also reason to conclude, that during a number of years, none but the aluminous basis was used for dying with cochineal in Europe,* until the accidental falling of a solution of tin by aqua-fortis, into a decoction of cochineal, about the year 1630, manifested the singular power of the oxide of that metal in exalting the colour of this drug, and led to a discovery of that most vivid of all colours the cochineal scarlet. Kunckel and others state this accident to have happened to a German, named Knse?w or Kuffler. But others, and particularly Beck- man, assert that it occurred to a Dutch chemist, Cornelius Drebbel, who was born at Alkmaar, and died at London in l634,t and that he com- municated this occurrence to Kuffler, who was an excellent dyer at Leyden, and afterwards be- came the son-in-law of Drebbel.J That Kuffler * Caneparius (de Atramentis, p. 191), mentions the dye " ex granis ficus Indicae Mexicani, quae prout semina sunt, eisque tinctores pro carlisino colore utuntur." Hence it appears that cochineal was then (1619) only used for dying crimson, at Venice, where the art of dying had long been most successfully practised. f If it be true that Drebbel died in London in 1634, he had probably come to England to derive some benefit from his dis- covery, and died before he had had time to do so. \ Mr. Macquer, in a memoir printed among those of the Academy of Sciences of Paris for 1768, says, " Dreb- bel, chimiste hollandois, a imagine d'employer dans la teinture s§ 448 PHILOSOPHY OF put the discovery into practice in his dye-house, and that the scarlet was thence first named Kuf- tlers colour, and afterwards scarlet of Holland, or Dutch. From him a Flemish painter, Kloeck or Gluck, learned the secret, and communicated it to one of the famous Gobelins at Paris ; and another Fleming, named Kepler, brought the secret to England about the year 1645, and the first dye-hcuse for dying the new scarlet having been soon after established at Bow, ne&r London, that colour was for some years called the Bow dye. It has been generally supposed, that after the effects of tin upon the cochineal colour had been de cochenille, de la dissolution d'etain faite par l'cnu regale, et des lors on a obtenu le plus vif et le plus eclatant de tous les rouges dont l'art, et meme la nature nous ait donnc l'idce ; je veux dire l'ecarlate couleur de feu, qui a porte d'abord le nom d'escarlate de Hollande, parce que e'est dans ce pays que les premieres manufactures ont ete etablies," &c. Mr. Macquer seems to have been mistaken in supposing that the first solutions of tin employed in this way were nitro- muriatic, or made with aqua-regia, there being very gocd reason to believe, that aqua-fortis alone, though perhaps im- pure, was used for some years for this purpose. Mr. Delaval, without the smallest probability, attempts to carry the first use of tin for dying back to very remote anti- quity ; and thinks the Phoenicians used that which they were said to have brought from Britain in this way, because (as Le erroneously asserts) " this is necessary to the production of red colours, whether from animal or vegetable materials." See Experimental Enquiry, &c. PERMANENT COLOURS. 440 'discovered, as before mentioned, nothing more was wanting to produce what is at present called scarlet, than to apply the colour so produced as a dye to wool ; or in other words, that a nitric, or nitro-muHatic solution of tin, was sufficient to change the natural crimson of cochineal to a scarlet. Such at least has been the opinidn of every writer on the subject until the present hour; though it will hereafter be proved to have been an erroneous opinion, and that the nitric solution of tin invariably produces (with co- chineal) a crimson or rose colour, and not a scarlet, unless other means be also employed to incline the cochineal colour, so far as may be necessary, towards the yellnzv; and the means of doing this seem to have been stum- bled upon, and continually employed without any knowledge of their true effect. I have al- ready mentioned that tartar is, and for many ages appears to have been, generally employed with alum, to compose the ordinary boiling li- quor or mordant for woollen cloths: and it seems probable, that when the first attempts were made to employ the solution of tin, instead of alum, it would naturally have been imagined, that as tartar had been found useful with the latter, it must also produce good effects with the former, and that a trial of it having been thus produced, and the most brilliant of all colours having been found to result from this combination of tartar 450 PHILOSOPHY OF with the solution of tin, their joint use was afterwards continued, without any inquiry con- cerning the particular share which either of them had in producing such pleasing effects. At first indeed a diluted nitric acid appears to have been employed for dissolving the tin without any admixture of the muriatic ;* but as the former would have held but a small por- tion of the calx of that metal in a state of sus- pension, and as even that portion would have been liable to precipitate in a few days, the practice of adding either a little muriate of am- monia, or a little sea-salt, to the aqua-fortis, and of thereby producing an aqua-regia, or nitro- muriatic acid, seems to have been introduced,, though it did not become general until a consi- derable time after; since Ilellot gives an account of the process. used in his time for dying scarlet at Carcassonne, in which tin was dissolved only by diluted aqua-fortis; and he mentions M. Ba- ron, as claiming the merit of having been tlie first in that city who employed an aqua-regia for dissolving tin, in order to prevent a precipita- tion oj its calx or oxide ; and even when this was done, the muriate of ammonia and sea-salt were added, but very sparingly, from a belief, which stiil subsists universally, that a more liberal use of either of them in this way, or of the muriatic * Doubtlss, 'he a iua-fortis was d.en impure, by containing, at least a *mall proportion of the muriatic acid, as it commonly does al thU time, PERMANENT COLOURS. 451 acid in their stead, would render the cochineal colour a crimson instead of the scarlet, which last is supposed to be a peculiar production of the nitrate of tin,* though nothing can be more groundless than this belief; since the nitrate, and the muriate of tin, both equally afford a crimson colour with cochineal, and neither affords a scarlet without the aid of other means. The dyers' ordinary solution of tin is made with that species of diluted nitric acid, called single aqua-fortis, and which, as usually pre- pared, is capable of dissolving about one-eighth of its weight of tin, grained or granulated, by pour- ing it, when melted, into water, briskly agi- tated with a bundle of rods, or by other suitable means. For each pound of aqua-fortis, it is usual to add after the rate of one or at most tw r o ounces of sea-salt, though some prefer, and probably with reason, the muriate of ammonia for this pur- pose. About half as much water as of aqua- fortis, is moreover commonly added, in order still farther to dilute the acid, and moderate its action on the tin. Those solutions of it which are made most slowly, and with the least se- paration of fumes or vapours, have been found * I give this denomination to solutions of tin produced solely by a diluted nitric acid, without regarding the decompo- sition more: or less complete, which the acid undergoes in con- sequence of such solution. GgS 452 PHILOSOPHY OF to succeed the best; probably, because in these the tin is less calcined, or oxygenated, and the solution retains a larger portion of azote, or nitrogene, than in those which proceed more rapidly. It is usual to allot after the rate of two ounces of grained tin to every pound of aqua-fortis : and the metal is put into it, at different times, waiting until one part is nearly dissolvedj before another is added, lest too much heat should be evolved, and the solution proceed too rapidly ; though there is no danger of this, in the latter part of the process, which indeed should be protracted so as to last two or three days. The water mixed with the aqua- fortis should be ascertained by weighing or mea- suring, in order that a proper allowance may be made for it in calculating the strength of the solution, or the weight of metal contained in a given quantity thereof, which, supposing half as much water as of aqua-fortis, to have been used, will be about one-fourteenth part of the whole ; and when the solution (which the dyers in this country generally call* spirit) has been made in these proportions, from eighteen to twenty-live pounds of it are commonly em- ployed to dye a full cochineal scarlet, upon one hundred pounds weight of woollen cloth ; and of this, quantity three fifths, or two thirds, are usually employed in the first preparation, or boiling part of the process ; for which sup- posing one hundred pounds weight of cloth are PERMANENT COLOURS. 45H i i tended to be dyed, about eight pounds of crude tartar or argol are put into a suitable dying ket- tle or vessel, (of pure block tjn 3 ) with a sufficient quantity of clean soft water * and six or eiaht otnces,of powdered cochineal. Immediately after this twelve or fourteen pounds of the solution of tin, prepared as before mentioned,are to be added, and when the mixture is nearly ready to boil, the cloth, being first thoroughly moistened, (that the dye may penetrate and apply itself equally thereto,) is put into the dying liquor, and turned through it (by the winch) very quickly at first, and afterwards more slowly, whilst the liquor continues to boil, for the space of an hour and a half or more, after which it is to be taken out, and rinced in clean water. By this first boilbig or preparation, th? cloth will have acquired a flesh colour. For the second, or dying process, a tin vessel is filled with clean water, and when this appears almost ready to boil, five, or if aj'uli colour be wanted, five and one half pounds of cochineal in powder are to be put into it, and well mixed, by stirring for a few minutes ; after which, the remaining part of the solution of tin is to be added, and the whole being well stirred, the cloth is to be put into the liquor, and turned very briskly through it, over * Hard water tends to produce a rose colour, which th« dyers commonly endeavour to obviate, by boiling bran or starck in their water. bb n 454 PHILOSOPHY OF the winch, for a little time, in order that both ends may receive an equal portion of the dye; after which it may be turned more slowly for the space of half an hour, or until the dying liquor becomes exhausted, when the cloth is to be taken out, aired, and rinced. An ounce of fine cochineal is generally deemed necessary for dying a pound of cloth ; but something less than this portion is fre- quently made to answer, especially for coarser cloths.* It is not, however, necessary to follow this (which is the usual) process for dying scarlet. I have often given that colour very well at one single though protracted boiling, by mixing the whole quantity of tartar, and solution of tin, and adding the cochineal, after the cloth has boiled ten or fifteen minutes; for such, in this case, is the attraction of wool for the colouring matter, as well as for the oxide of tin, that it will take up both very freely, and retain them permanently, when thus mixed. I think, how- ever, that in this way the cloth may be liable to imbibe both the mordant and the colour, with some inequalities, by reason of the differences * Hellot directs an ounce of cochineal for eacli pound of fine cloth. Berthollet prescribes six pounds of cochineal for every lOOlbs. of cloth. Mr. Hawker, a very eminent scarlet dyer in Gloucestershire, assured me, that for fine cloths he commonly employed four pounds of cochineal for every 60lbs. of cloth ; but that for coarse cloths he seldom exceeded two pounds and three quarters for that quantity of cloth. PERMANENT COLOURS. 455 which are found to subsist not only in the wool of different sheep, but even of the same indi- vidual, when taken from different parts of the body, as was noticed at p. 85 ; and that it will therefore, always be safest to employ a. previous boiling, in the manner commonly practised, to overcome the effect of these inequalities, by forcing a sufficient quantity of the mordant or basis, into the pores even of those sorts of wool which are the least disposed to receive it. This boiling may, however, be shortened to a single hour, when it is performed with what the dyers call 'dseciso)iedJloat,meim'mg the bath or preparation liquor which, after having been employed for the same purpose, is replenished according to the ordinary practice, with a fresh portion of the mordant, &c. and thus rendered more efficacious than the Jirst. I have moreover often dyed very beautiful scarlets, by preparing or boiling the cloth with the whole quantity of solution of tin and tartar at once, (as is commonly done with alum and tartar,) and afterwards dying it unrinced, with the whole of the cochineal in clean water only ; and in this way I have found the colouring particles so completely taken up by the cloth, that the liquor became as clear as the purest water, and the colour was generally very perfect. Most dyers, besides the tartar used in the first boiling, employ half as much of it as of 456 PHILOSOPHY OF cochineal in the second, or dying part of the process ; and certainly the doing so will be ad- vantageous, whenever the colour is wanted to approach nearer than ordinary to the orange tint, though this is not the effect which would be generally expected to result from thence. Pccrner uses no cochineal in the first jboiling, nor indeed is any necessary, though a little may probably help to decompose the oxide of tin, and fix it more copiously in the 'fibres of the cloth. For scarlet, many dyers prefer the red argol or crude red tartar ; but the matter to which it owes this colour is wholly incapable of adding any colour to that which the wool might otherways acquire, and therefore at best its redness will prove useless. Wool is seldom dyed scarlet until it has been spun, wove, and fulled ; because the yellowish tendency which the cochineal colour acquires from tartar in the dying process, is nearly all taken away in the fulling, and a rose produced instead of a scarlet colour. M. Berthollet thinks the solution of tin, before described, does not affect the cochineal colours, merely by the proportion of that metal which it contains; and that when either sal- ammoniac, saltpetre, or common salt, enter the composition of an aqua-regia, the compound will be less acid than when it consists of the nitric and muriatic acids solely; and that the .former deserves therefore to be preferred, as PERMANENT COLOURS. 457 Jiaving a less violent action upon the fibres of woollen cloths, and upon colouring matters. It is remarkable, that during the present cen- tury, no considerable improvement has been made in the process or means of dying scarlet ; a circumstance which is the more extraordinary, since the pre-eminent lustre, as well as the costly nature of this dye, have rendered it an object of particular attention, not only to dyers, but to eminent chemists, by whose researches we might have expected, that at least every obvious im- provement therein would have been long since attained. That this, however, has not been done, will, 1 think, manifestly appear, by the following statement of my own particular ob-. scrvations and experiments on this subject, which began in the year 1786. Having then been led to pour boiling water repeatedly upon pow- dered cochineal in a china bason, and to decant it as often from the subsiding insoluble parts, until they would yield no more colour, I found that by adding a little pot-ash, or soda, to this seemingly exhausted sediment, and pouring fresh boiling water thereon, a farther copious extraction of colour instantly displayed itself, equal, as far as I could judge, to about one- eighth of the whole of that which had been originally contained in the powdered insects; and having by repeated trials, constantly found this effect, I too hastily concluded, that the colour thus obtained by the help of pot-ash, 45S PHILOSOPHY OF was so far of a resinous nature, or so inter- mixed with a resinous matter, as to have always been incapable of being extracted by the means usually employed for dying with cochineal ; and that if it should be found ca- pable of yielding colours as beautiful and per- manent as those dyed with the more soluble colouring particles of these insects, an acqui- sition might be made of so much new colour- ing matter, which till then had, as I con- ceived, been always thrown away. That it was capable of yielding such colours, I soon ascer- tained, by repeatedly extracting this particu- lar colouring matter by the help of pot-ash, and afterwards dying small pieces of cloth with it, (in the ways usually employed for dy- ing scarlet), and by comparing and exposing them to the weather with other pieces dyed from the more soluble colouring matter of co- chineal. Continuing my inquiries on this subject, I soou perceived that the colour, denominated scarlet, must in fact be a compound colour, (like green, purple, and orange), consisting pro- bablv of about three-fourths of a most livelv pure crimson or rose colour, and about one- fourth of a pure bright yellow ; and that there- fore, when the natural crimson of the cochineal is made scarlet by the means always hitherto employed for dying that colour, there must be a change produced, equivalent to a conversion PERMANENT COLOURS. 459 of one-fourth of the cochineal colouring matter from its natural crimson to the yellow colour ; and as a hetter yellow might he obtained from other drugs, where it naturally exists, and for a fiftieth part of what it costs when obtained in this way, from the most costly of all dying drugs (cochineal), it necessarily followed, that this, the universal and only known method of producing a scarlet, must be highly injudicious, because unnecessarily expensive. Convinced of this important truth, and at the same time believing too easily, on the, authority of Hellot, Macquer, and others, that the natural crimson of cochineal was rendered scarlet only by the nitric acid employed to dissolve the tin used in dying that colour, I began a series of experiments for producing it, without any such waste of the cochineal colouring matter. For this purpose it seemed necessary to discover a mordant or basis, capable of permanently fixing and strongly reflecting the pure vivid cochineal crimson, or rose colour, without making it incline to the yellow. 1 concluded, and found hy experiments, that the necessary purity and vivacity of colour could not be obtained from an aluminous basis, however dissolved, though it doubtless fixes the colouring particles of cochineal more durably than any other mor- dant ; and the like defect was found to accom- pany the solutions of all the other earths, as 460 PHILOSOPHY OF well as of the metals, tin alone excepted ; aiwl with this farther disadvantage, that most of them either degraded or altered the natural co- lour of cochineal very considerably. It fol- lowed, therefore, that a basis to suit my pur- pose must be sought for in the pure white calx or oxide of tin, so dissolved or combined, as to Teflect the cochineal crimson unchanged, and With the greatest possible lustre. Misled by what those eminent writers Dufay, Hellot, Mae- quer, Scheffer, &c. had advanced, as well as by the opinions of others, with whom I had con- versed on this subject, I erroneously concluded, that all solutions of tin, in which the nitric acid predominated, would necessarily incline the cochineal crimson towards the yellowish tint, and that therefore such solutions ought to be excluded from my experiments. In this persuasion, I dissolved parcels of "that metal in almost every other acid, and tried them sepa- rately for dying with cochineal. Their several effects will hereafter be more particularly stated : at present I need only mention, that of all others the muriatic solution seemed the best suited to answer my purpose, as it both fixed and re- flected the pure crimson or rose colour of the cochineal unchanged,* and with the utmost * It must be observed, that when in this and other places I mention the crimson colour as produced by cochineal upon a tin PERMANENT COLOURS. 461 brightness. To produce a scarlet, therefore, it was only necessary to superadd, and intimately combine with this crimson or rose colour, a suitable portion of a livety golden yellow, capa- ble of being properly fixed and reflected by the same basis. Such a yellow I had previously discovered in the quercitron bark, (which will be the subject of a future chapter,) and also in what is improperly called young fustic, (Rhus Cotinus, Linn.) though its colour was less bright, and less durable, than that of the quer- citron bark. This last had also the advantage of being not only the brightest, but the cheapest of all yellows, since one pound of the bark in powder, which cost but three-pence farthing, dyed, with a sufficient quantity of muriate of tin, between thirty and forty pounds weight of woollen cloth of a full bright golden yellow ; and this being afterwards dyed in the same liquor, with one-fourth less of cochineal than what is usually employed, acquired a scarlet equal in beauty and durability to any which is usually given by the ordinary means, with a full proportion of cochineal; and such were the general results of a great number of expe- riments. basis, I mean a colour much more lively and beautiful than the crimson dyed from cochineal upon an aluminous basis. The former might, perhaps, with more propriety, be denominated a rw{ colour. AG2 PHILOSOPHY OF The quantity of muriatic solution of tin ne- cessary to dye a given quantity of scarlet in this way, see ed to me at that time to depend on the proportion of metal contained in it, and this last to depend on the strength of the acid used for tins purpose.* That which I employed, and which I bought at the price of 38s. per 112lbs. or about four-pence per pound, dis- solved in a strong sand-heat, one-third of its weight of granulated tin; and this solution would, with the proportions of cochineal and bark before mentioned, dye about ten times its weight of cloth, of a good scarlet colour. I have said that three pounds of muriatic acid, which cost but one shilling, might be made to dissolve a pound of tin, which would require eight pounds of single aqua-fortis to dissolve it; and this quantity of aqua-fortis, at the rate of 8d. peril), would cost 5s. 4d., so that on each pound of tin dissolved by muriatic acid, instead of the nitric, I calculated a saving of 4s. 4d. The muriatic acid, therefore, which M. Beaume* * I have since ascertained, by decisive experiments, that muriatic acid, which has only dissolved one -half of the portion of tin which it may be made to dissolve, will go as far as an equal quantity of acid which has been saturated with the metal, and that the elects of the former are in every other respect bet- ter than those of the saturated solution, so that this last is.it best an useless expenditure of one-half of the tin which it contains. PERMANENT COLOURS. 461 had styled the true dissolvent of tin, (" le yrai " Jissolvant dc l'Etain,") seemed also to be of all others the cheapest; and with this farther advantage, that a solution made by it was as transparent and colourless as the purest water, and capable of being preserved for many years, in vessels closely stopped, without the least al- teration, whilst the dyers' nitro-muriatic solu- tion of tin or spirit becomes turbid or gelati- nous very speedily, and even in a very few days, if the weather be warm. I may add also, that the muriatic solution of tin seemed to exalt the colours both of the quercitron bark and of cochineal, more than any other. I perceived, moreover, another advantage re- sulting from this new method of dying scarlet, by a saving of all the tartar employed in the old, Before I began my experiments on this subject, I had endeavoured to learn the purpose which tartar was intended to answer in the usual pro- cess for dying scarlet; but having obtained no satisfactory answer on this point, I doubted of its producing any good effect, and therefore omitted it in my first trials; and as they suc- ceeded, I also omitted it in all the others. By these facts and ideas I was led to believe that I had made discoveries likely to produce, very important national beneiits : and I parti- cularly calculated in the first instance a gain of about 1£* per cent, upon the whole quantity of 464 PHILOSOPHY OF cochineal consumed in Great Britain, by that part of its colouring matter, which I proposed to extract by the help of pot-ash, or soda, and which I supposed to have been before always lost. Besides this, I computed that a saving of 25 per cent, upon all the cochineal used iu Great Britain for dying scarlet, aurora, and orange co- lours, would result from my plan of obtaining from the quercitron bark so much yellow as was required for the composition of those co- lours with the cochineal crimson, instead of con- verting any part of this last more costly colour into a yellow. And lastly, I calculated other savings, equal at least to 20,0001. annually, in the article of tartar, (acidulated tartrite of pot-ash,) and in what the muriatic solution of tin was likely to cost less than that which is commonly used for the purposes in question. With this opinion of the importance of my discoveries on this subject, I gave an account of them, as well as of an improvement in the black dye, (which will be hereafter explained,) to the Right Honourable the Lords of the Committee of his Majesty's Privy Council, appointed for the consideration of all matters or' trade, &c. (of which committee the late Earl of Liverpool was President), and their lordships, with a lauda- ble solicitude for the public welfare, were pleased, by an order, bearing date at Whitehall,. PERMANENT COLOURS. 465 the 18th of September, 1787, to refer the same to " six capital dyers, named in the said order, who were desired to inquire into the facts re- specting the said important discoveries in the black and scarlet dyes;" and afterwards " to report to the committee their opinion of the merits and utility" thereof. It was not, however, until the 22d of Ja- nuary following that an experiment relating to the scarlet dye was made at the dye-house of Messrs. Goodwin, Piatt, and Co., Bankside, Southwark. Considering, on that occasion, how much practical operators, in all the arts, are in- clined to distrust improvements offered by spe- culative men upon the grounds of theory or philosophical reasoning, I was desirous of making my first trial, under the most favour- able circumstances, in order that by its signal success, I might effectually obviate the effect of any unfavourable prepossessions in the minds of those who were to report on the merits of my discoveries. For this purpose I prepared a large quantity (near lOOlb.) of the muriatic solution of tin; and in order that the acid might be per- fectly saturated with the metal, I added an over- proportion of the latter, and kept both at the boiling point, by means of a sand heat, for the space of three days and nights. In this way I obtained a solution perfectly colourless, of a very pungent smell, and so highly volatile and elastic, Hh mm ■*«**: 466 PHILOSOPHY OF that it was impossible to prevent its escape from the vessels in which it was contained, however closely stopped. It was, in fact, but little different from the fuming liquor of Liba- vius, in which dry muriatic acid is saturated with tin; but this complete saturation, instead of proving beneficial, as I had expected, be- came an obstacle to my success ; because the union between the acid and the metal was thereby rendered so intimate and powerful, that the affinities of the cloth and the colouring matter of the bark could not overcome it, except in a degree too small to afford a sufficient basis for the cochineal colour ; and farther quantities of the solution being therefore added, to supply this deficiency, (from an erroneous notion respecting the cause of it) the texture of the cloth was by these additions greatly weak- ened and injured. Two pieces of long baize, weighing together ISSlbs. had been chosen as the objects of this experiment. I had before observed, in my pri- vate trials, that the colour generally proved most lively when given with a full proportion of the muriate of tin ; and also that the colouring mat- ter of the cochineal was most completely im- bibed and taken up out of the dying liquor by the cloth, when the whole portion of the solu- tion of tin, instead of being applied at different times, was boiled up at once with the quercitron PERMANENT COLOURS. 467 bark ; an effect the more desirable for me at that time, because I intended to employ a very small proportion of cochineal, and therefore wished to leave as little as possible of its colouring matter behind, floating in the dying liquor, especially as it would be difficult pro- perly to estimate the exact quantity remaining therein. For these reasons, I took a large portion of the solution of tin, i. e. 161b. weight for the two pieces of baize, and threw the whole of it at once, with five pounds of powdered quercitron bark, into a suitable tin vessel* properly filled with water a little warmed, into which the pieces of baize (previously moistened) were soon after put, and turned as usual over a winch through the liquor (which was made to boil) for the space of an hour, when they were both taken out and rinced in clean w r ater, the dying * For a considerable number of years, the scarlet colour had been constantly dyed in vessels made, or consisting wholly of block tin. Very lately, however, it has been found that copper bottoms might be given to these vessels without inju- ring the colour, and with a great saving of expence, as they prove much more durable, and the copper is but little acted upoi when secluded from atmospheric air, by being covered with water, &c. and even in the dying operation, the acids are more disposed to exert their action upon the tin of which the upper part of the vessel consists, and upon the cochineal and the cloth, than on the copper bottom. h1i2 mi ■ -468 PHILOSOPHY OF vessel being at the same time emptied, and then filled again with warm water for the remaining part of the operation. The baize had, in this first boiling, acquired a very bright golden yel- low, though but about one-fortieth part of its weight of bark was employed ; and I had ex- pected, from what had before happened in my own particular experiments, that it would have been so fully impregnated by the metallic basis, as to want no farther addition of the muriate of* tin in the second part of the process. To secure myself, however, against a disappointment on this point, I cutoff a bit from one of the pieces, and boiling it in a small pipkin with water, and a little cochineal, I saw with great concern that the fibres of the cloth were very far from having imbibed enough of the oxide of tin to fix and raise the cochineal colour ; and that a farther portion of the solution would be absolutely ne- cessary for this purpose. The cause, indeed, of this disappointment, was only ascertained by subsequent experiments, though it might have been conjectured at that time, as the water into which the solution of tin had been poured in the dying vessel, did not decompose any part of it, or become in the slightest degree milky or turbid, as it docs with other solutions of that metal; and the attraction of the woollen cloth was evidently much too feeble to separate and attach to itself any part of the oxide of tin, PERMANENT COLOURS. 469 excepting that which had united with the co- louring matter of the bark, and by this addi- tional affinity became fixed in the wool as the basis of that golden yellow which it had received, as already mentioned ; whilst the other and greater part of the oxide remained in the water, (combined with the muriatic acid,) and was thrown away with it after the first boiling, but unfortunately not without having previously weakened the fibres of the wool by its corro- sive property, of which I had no suspicion, until it became manifest in the second part of the operation. For this, five pounds of co- chineal were put into the dying vessel, with six pounds more of the muriate of tin, and being well mixed in the water, the two pieces of baize were put into the liquor, and dyed therein for about fifteen minutes, when the colour not seem- ing to rise properly, four pounds more of the solution of tin, and one pound of cochineal, were added ; and the dying was continued, until it appeared soon after that the texture of the cloth was greatly injured by the muriate of tin,* * Subsequent experiments have proved, that if my purpose of employing the yellow of the quercitron bark, in conjunction with a rose colour from cochineal, wouid have allowed me to add the usual portion of tartar on this occasion, the injury sustained by the cloth might have been completely obviated ; for the acid of the tartar, like every other acid which I have tried, greatly corrects this hurtful sort of action, which the muriate of tin 470 PHILOSOPHY OF which seemed in this, as well as in subsequent trials, to have a much stronger and more cor- rosive action upon the fibres of wool than other solutions of that metal, though before that time 1 had always been persuaded that it would on the contrary have acted more mildly in this respect than the ordinary dyers' solution or spirit ; and indeed I had been led to this persuasion by the concurrent opinions of several very eminent chymists, who had all represented the nitric acid as ex ei tine a stronger and more corrosive ac- tion than the muriatic upon animal substances. Even that very excellent chymist Berthollet has observed, in the tenth volume of the Ann. de Chyinie, published so lately as the month of August 1791, and after he had been particu- larly employed in examining the effects of the different acids upon wool and silk, that " l'acide " sulphurique & l'acide muriatique exercent une *' action moinsvive sur les substances animales " que l'acide nitrique suihsamment concentred" And this doubtless is true of these acids acting merely as acids ; but. very different properties appear to result from their combinations with when employed alone, exercises en wool or woollen stuffs. The tartar would, moreover, have rendered the muriate of tin, more susceptible of decomposition, by affording a portion of superfluous or uncombined acid, so that less of the muriate of tin would have been sufficient. PERMANENT COLOURS. 471 metals, and metallic substances ; among which, the metallic solutions by muriatic acid seem ge- nerally more corrosive than those made by any other. This is particularly true of the mu- riates of mercury, silver, lead, bismuth, and antimony, as well as that of tin ; but the corro- sive nature of this last, and the difficulty of de- composing it, seem to be increased, in propor- tion as the muriatic acid is more completely sa- turated or combined with a greater portion of the metal. It is indeed true, that the propor- tion of solution of tin used in the foregoing experiment, was much greater than I ha d ever before employed, as it amounted to 261b., and contained above six pounds of the metal, which is four times as much as would suffice (dissolved by a mixture to be hereafter explained) for the same weight of cloth. But still I am persuaded, that an equal quantity of any other solution of tin would not have injured the like quantity of cloth in an equal degree ; and being thus made sensible of the danger that must attend the use of a mordant so corrosive, I was convinced of the expediency of searching for one more harm- less in this respect, though it certainly is very possible, with proper care, to employ the mu- riate of tin (containing a smaller proportion of the metal) so as to produce all the good effects which I had expected from it, without any in- jury to the cloth, as I have found by a multi- 472 PHILOSOPHY OF tude of experiments since, as well as before, that of the22d of January, 1787- Whence this corrosive property of the mu- riate of tin arises, may become a subject of future inquiry. At present I shall only observe, that in some experiments which I made, with the hope of correcting it, I constantly found this saturated muriate of tin, possessing a strong- attraction for oxygene, and that by absorbing it, as it did from various matters, its corrosive property was always greatly diminished. This led me to oxygenate the muriatic solution of tin, by putting a very little manganese into it, or rather by dissolving tin with a very little manganese in muriatic acid ; but though the solution made in this -way appeared less corrosive, it contained a small portion of the manganese, which darkened the cochineal colour, making it incline towards a purple. 1 afterwards oxygenated the muriatic acid, by mixing it with about one-third less than its own weight of the nitric, and with this I made a solution of tin ; which appearing to be no more corrosive than the common dyers' spirit, and not changing the cochineal crimson to- wards the yellow hue, I was hastily induced to venture with it upon another trial at the dye- house of Messrs. Goodwin and Co. a few weeks after the first. It was, however, made only on one piece of baize, weighing about ninety PERMANENT COLOURS. 47$ pounds, which I caused to be boiled with about eight pounds of this muiio-nitric solution of tin, and two pounds and one-half of powdered quercitron bark. This mordant, however, acted very feebly, or rather failed, in exalting- the yel- low colour of the bat k, which took but very slowly on the baize, and never rose much higher than a straw colour, even after two hours boil- ing ; when a considerable quantity of yellow colour, united to the calx of tin, evidently remained floating in the water, not because the calx was too intimately combined with the acid solvent, as in the first experiment, — but because, for want of a sufficient attraction between them, it had been almost wholly decomposed as soon as they were put into water : and in boiling, it fixed itself with the bark colour upon the cloth very sparingly, superficially, and slowly. This also happened in the second part of the opera- tion ; for which three pounds of cochineal, and six of this murio-nitric solution of tin, were at first employed ; but the colour not rising sufficiently, another pound of cochineal, with four pounds more of the same solution, were added to the liquor in which the cloth was dyed for the space of two hours, when a considerable part of the colour still appeared floating, but not dissolved, in the water. So much, indeed, had been applied to the cloth, as to give it a passable scarlet colour, which, however, had •£M&^i£&^^ ^mmm K mm% ■^■■■■■■1 m 474 PHILOSOPHY OF penetrated but very little into its substance, so that the cloth seemed, as Mr. Goodwin obser- ved, to have been rather painted than dyed.* It * According to my best recollection, the solution of tin era- ployed for this experiment had been made eight or ten days before it was so employed, and during this interval the metal had probably become too much oxygenated : and it had more- over the disadvantage cf being u^ed without the aid of tartar, which by its acid seems to enable the oxide of tin, as well as th« cochineal colour, to penetrate and unite morecopiously with the fibres of wool. I very lately (Nov. 1812), mixed three ounces of strong nitric acid of the specific gravity of 1500, with seven ounces of muriatic acid of the specific gravity of about 1 165. The mixture, as is usual, effervesced, and assumed for a short space of time a deep red colour. In this mixture diluted with six ounces of water, I dissolved two ounces of fine granulated tin, and the next day employed a suitable portion of it, with cochineal and cream of tartar, to dye a small piece of broad-cloth. I observed, on putting the solution of tin into the water, that it collected therein like small loose dispersed curds, which, however, by a little boiling with the tartar, were com- pletely dissolved, and the cloth being put into this liquor with a part of the cochineal, and boiled in it as usual, and afterwards dyed with the remainder of the cochineal and more of the solution of tin and tartar, imbibed, contrary to my expectation, a very Jnlght good scarlet, excepting that it inclined a little too much to the orange tint. In this case the colour had pene- trated and united itself to the cloth as expeditiously as with the solution of tin commonly employed by the dyers, and with- out any such difficulty as I had experienced in my second expe- riment at the dye-house of Messrs. Goodwin and Co. ; an ad- vantage which must, as I think, have resulted from my having in this latter trial employed the solution of tin when recently PERMANENT COLOURS. 475 was, however, generally agreed, after a parti- cular examination, that notwithstanding the great length of time in which the haize had been boiled with a very large proportion of the so- lution of tin, (i. e. 1 Sib. for a single piece weigh- ing but 90ib>), its texture had not received the smallest injury ; so that in this respect my last experiment proved less expensive than the first, though both together cost me nearly 30/. As this murio-nitrate of tin, though exempt from the defects of the muriatic solution, had failed through others of a very opposite nature, I was induced to mix much greater proportions of nitric with the muriatic acid for dissolving tin, in order to see how much of the former could be used in this way, without so far yellow- ing the cochineal crimson as to preclude the use of any of the quercitron yellow in the dying of scarlet, an effect which I still expected from the nitric acid, when used in a very large propor- tion ; but, to my great surprize, I could disco- ver no such effect, even when I had dissolved the metal in nitric acid alone. At first I sus- pected some impurity in the acid which had made, and in conjunction with the tartar, which was omitted in the former : but I will endeavour to ascertain the truth on this point by future trials with the same solution, after it has been kept during various longer periods, and also with and without the co-operation of tartar, and mention their results in a post- script to my second volume. ' , 'V' : 476 PHILOSOPHY OF been employed ; but having procured a fresh supply, and ascertained its purity by the proper means, I still found that tin dissolved by it had not the least tendency to change the cochineal crimson towards a yellowish or scarlet hue ; and that this effect, in the usual waif of dying that colony, resulted wholly f torn the tartar, (acidu- lated tartrite of pot-ash,) which is always em- ployed at the same time. This fact I ascertained by repeated and varied experiments, ill which I constantly found that cochineal, with the dyers' common solution of tin, and even with that made by nitric acid only, would produce nothing but a crimson without tartar; and that cochineal, with tartar, Avould produce a scarlet, not only with these last-mentioned solutions, but also, and equally well, with the muriatic solution of that metal ; and therefore, that every thing which had been taught and believed to the contrary was repugnant to truth. And here I cannot conceal my wonder, that an error of so much consequence, and so destitute of all foundation, should have been propagated and confirmed by so many acute reasoners and sagacious observers in other respects ; for, be- sides those eminent writers already mentioned, Mr. Pcerner has more recently adopted and pro- pagated the same error, after making a great number of experiments, several of which, if they had been duly considered, would have PERMANENT COLOURS. 477 taught him the truth on this subject.* This also was even more lately done by M. Berthol- let, in his El&nens de l'Art de la Teinture, where, to adopt the words of Dr. Hamilton's Translation, he says, " Tartar, as we have seen, gives a deeper and more rosy hue to the colour- ing matter of cochineal, precipitated by the solution of tin. It moderates the action of the nitro- muriatic acid, which tends to give scarlet an orange cast, though this orange cast is not to be seen in the precipitate pro- duced by the solution of tin, which is on the contrary of a fine red. It is probable that the solution of tin gives scarlet an orange tinge, by means of the action the nitro-mu- riatic acid exerts on the wool, which, as well as all other animal substances, it has the pro- perty of turning yellow.")" " Thus (adds he), by putting more of tartar into the reddening, a deeper and fuller scarlet mav be obtained ; and on the contrary, the scarlet may be rendered more inclining to orange by omitting this ingredient."' And he concludes the chapter by repeating this doctrine. Here then it is manifest, that the nitro mu- * See Instruction sur l'Art de la Teinture, &c. a Paris, IjQl. f It is true that nitrie acid alone makes wool, &c. yellow, but wool or cloth, boiled with nitro-muriale of tin, as a-prepa- ration for scarlet, remains perfectly white, if no colouring i3 mixed with it, as is well known. ^H HEHH Hi 5! 47s PHILOSOPHY OF riate of tin and the tartar are each supposed to produce effects directly contrary to those which arc really produced by them, the effects of each being ascribed to the other; a mistake capable of producing much disappointment and detri- ment.* * M. Berthollet, with his usual and becoming candour, has, in the last edition of his Elements, &c. admitted the error into which he had fallen, in common with all others, on this subject, and the truth of my observations respecting it. " On avoit, (says he) dans la premiere edition de ces elemens, attribue au tartre la propriete de donner une nuance plus foncee et plus rosee aux parties colorantes de la cochenille : cette opinion pouvait meme etre regardee comme generate ; viais Bancroft ta comhatlue avec raison : il pretend que si Ton supprime le tartre, on a une couleur cramoisie ; que le tartre donne naissance & un tartrite d'etain insoluble, qui fait avec la cochenille une couleur jaune ; que l'ecarlate ordinaire est un melange d'un quart de cette cou- leur jaune et de trois quarts ou un peu plus de la couleur cra- moisie que donne la cochenille avec la dissolution d'etain," Sec. And after mentioning my proposal for obtaining the yellow part of the scarlet colour from the quercitron bark, rather than from cochineal, he gives an account of three experiments which he had made by dying sloth with cochineal and a solution of tin; fcr two of which he also employed tartar in the ordinary, and in a double proportion : and he found that in proportion to the quan- tity of tartar employed, the colour inclined to the yellow tin . whilst that without tartar "avoit couleur vineuse et moins vive," &c. He adds, " il est done vrai que le tartre fait incliner au jaune la couleur de la cochenille, et qu'il produit d'autant pks cet effet, que la proportion en est plus grande," &c. Elemenf, torn. ii. p. 179, 180. I must observe, however, that the explanation here give* by M. Bertholjet, of my conclusions in regard to the effects d PERMANENT COLOURS. 479 Having made myself certain that the dyers' spirit, or nitro-muriatic solution of tin, without tartar, would only dye a crimson with cochineal, I was induced to make an experiment therewith, instead of the muriate of tin, at the dye-house of the late Mr. Seward, in Goswell-street, and with views similar to those which directed the experi- ments hefore made at the dye-house of Messrs. Goodwin and Co. A piece of baize was accordingly hoiledonehourandaquarter with the usual portion of nitro-muriatic solution of tin, (which had been prepared by Mr. Seward,) and with about one- fortieth of its weight of quercitron bark, with- out any tartar: After which it was taken out dyed of a bright yellow, though paler than it tartar in the dying of scarlet, is not quite correct. I have never intended to decide, that the acid of tartar formed an insoluble tartrite of tin, and that this tartrite changed the colour of a part of the cochineal to a pure yellow, and thereby gave to the other part a scarlet tint j though I have in fact supposed this as an ultimate effect to result from the action of tartar. But I intended to leave it undecided, whether the acid of tartar 3cted conjointly with the other acids and the tin, orseparately with the meial, in producing a scarlet instead of the rose colour, which would have been produced without it ; and though I supposed the amount of fhis change to be equivalent to a conversion of nearly one-fourth of the cochineal colour to a yellow, yet I did not assume that the change in question had been operated or effected in a fourth or any other part exclusively, raiher than on the whole collectively. Indeed, I have never found the tartrite of tin, even when employed alone with cochineal, able to render the colour yellow, though it produces a very yellowish scarlet. ■ 4S0 PHILOSOPHY OF would have been with the muriate of tin. The baize being rinced, and the dying vessel emptied, and then filled a second time with clean water, about four-fifths of the cochineal usually employed for the like quantity of baizr, and a farther suitable proportion of the solution (if tin, were put into it, and the baize being- dyed therein, as usual, took what was allowed to be a good scarlet. Air. Seward, however, did not seem so fully convinced, as I had ex- pected, of the advantage of compounding a scarlet in this way from the cochineal crimson and quercitron yellow ; and probably the expe- riment had not been attended with any very manifest success, or saving of cochineal, be- cause the nitro-muriatic solution of tin which had produced but a pale yellow with the quer- citron bark, had also acted more feebly in raising or exalting the cochineal colour than it usually does when assisted with tartar, which consists of a portion of vegetable alkali com- bined with an excess of its own peculiar acid ; and therefore, whenever it is mixed with a so- lution of tin by any of the mineral acids, the tartar will be decomposed ; because the mineral acids, by their superior attraction for, will unite with its alkaline basis, and disengage an addi- tional portion of the tartarous acid, which will then unite with the metallic oxide, previously abandoned by the mineral acid, and thus pro- PERMANENT COLOURS. 481 duce a tartrite of tin, which last, in the usual way of dying scarlet, inclines the cochineal crim- son to the yellow tint, and at the same time, (as I have since found,) exalts its colour more than the nitro-nmriatic solution of tin alone would be able to do; and it is only this de- composition of the tartar, that has obviated the ill effects which otherwise must have resulted from the sulphuric acid, frequently contained in the common aqua-fort is used by the scarlet dyers. # * This statement, first made in 1 794, respecting the effects of tartar with sulphuric acid j is partly erroneous, or liable to misconception : wherever that acid (the sulphuric) acts upon tin, either alone, or with any mixture containing nitric acid, the oxide of that metal, probably by too much oxygenation, is brought into a state which renders it incapable of producing with cochineal any thing better, or approaching nearer to scarlet than an orange, or at most a high salmon colour. It is true, in- deed, that if oil of vitriol, be put either into the scar)et dying, or the preparation liquors, immediately after, or conjointly with the tartar, it will do no harm, provided the quantity be only suf- ficient to decompose the tartar, and ventratize its alkaline part. But as no r,ir:ai is employed by the dyers ;n making their ordi- nary solution of tin. and as the aqua- fort is . sed for that purpose, frequently contains a little sulphuric acid, 1 j^ ia ter will have produced a' 1 its mischievous •.-fl-.-cts upon the tin, previously to the dying operation, and those effects will not afterwards be overcome by the tartar en pioyed in that operation. Fortunately, however, the mischief v bi< i m ^ht be produced by • Jittle sul- phuric acid mixed with the aqua-fortis employed by the dyers to dissolve their tin, is commonly obviated, without their being sen* sibie of it, oy their practice of making a imro-muriatic acid, not i i 432 PHILOSOPHY OF Though I had hitherto failed in my en- deavours to compose a scarlet colour with advantage, so as to save that part of the cochineal which appeared to be misapplied, by being yellowed in the usual process, I had nevertheless full confidence in my former reasoning on this subject, and employed myself from time to time in searching after more suit- able means for attaining this end. Some of my earliest experiments with a solution, or rather a calcination of tin by the sulphuric acid, had shewn me that this preparation was very unsuit- able for my purpose, because it really exerted a destructive action on the cochineal colour, by reducing it from a crimson down to a kind of salmon colour, which indeed was the highest colour produced on cloth by dying it with cochineal and sulphate of tin ; I therefore clis* carded the use of sulphuric acid for dissolving tin, until particular circumstances led me some time after to dissolve a portion of it by the mu- riatic acid, combined with about one-fourth of its weight of oil of vitriol ; and by trying this solution, 1 found that it produced very good by mixing the muriatic simply with the nitric acid, but by adding to the latter a portion either of sea-salt, or of muriate of ammonia, either of which affords an alkali, which, by its stronger affinity for the sulphuric, than for either the nitric or muriatic acids, combines with and neutralizes the former, when the quan* tity is not too great, and thus renders it bannles*. PERMANENT COLOURS. 483 effects in dying, without any appearance of that corrosive property which had acted so mischiev- ously in the experiments made with tin, dissolved by muriatic acid only. I was therefore encou- raged to make and try other solutions of that metal, by the same acids, united in various pro- portions ; and have at length found reason to prefer a solution made by dissolving after the rate of about fourteen ounces of tin in a mix- ture of two pounds of oil of vitriol, (of the usual strength,) with about three pounds of muriatic acid. That which I have used was of the specific gravity of nearly 1170, and strong enough, with a sand- heat, to dissolve one-third of its weight of tin. The muriatic acid should be first poured upon a large quantity of granu- lated tin, in a capacious glass receiver, and the oil of vitriol afterwards added slowly ; and these acids being mixed, should be left to satu- rate themselves with tin, which they will do in a longer or shorter time, according to the tempe- rature of the atmosphere, without any artificial heat; but the solution may be rapidly promoted by a sand heat. This solution contained but little more than half as much tin as the muriatic solution which had been used in the first experiment made at the dye-house of Messrs. Goodwin and Co., yet the metallic part of it existed in a state so much i i 2 484 PHILOSOPHY OF more suitable for the purposes of dying, that a given quantity of it would produee much better effects than a like quantity of muriatic solution, containing nearly twice as much of the metal, and without any corrosive property, capable of doing the least mischief, unless used in much greater proportions than ever can be wanted for dying.* The murio-sulphuric solution of tin, made in these proportions, will be perfectly transparent and colourless ; and will probably remain so for many years, without becoming turbid, or suf- fering by any precipitation of the metal ; at least, none has appeared in some which I have kept for more than three years. It will produce full twice as much effect as the dyers' spirit, or nitro-muriatic solution of tin, with less than a third of the ex pence. It has, moreover, the property of raising the colours of, 1 believe, all adjective dyes, more than the dyers' spirit, and full as much as the tartrite of tin, without changing the natural crimson of cochineal towards the 3 ellovvish hue ; and, therefore, after * Since my first edition of this volume was published, I have ascertained that even the proportion of tin here mentioned is unnecessarily great, and that equally good effects may be ob- tained with the same quantity of acids, when the latter contain but iittle more than half the quantity of tin which they ar« enable of dissolving. PERMANENT COLOURS. 485 having made a great number of experiments with it, I think myself warranted in strongly recommending this murio-sulphate of tin for dying the compound scarlet colour already described, (with the cochineal crimson and quercitron yellow,) for which it will be found highly effectual and oeconomical. For this species of scarlet nothing is neces- sary but to put the cloth, suppose 1001b. weight, into a proper tin vessel, nearly filled with water, in which about eight pounds of the murio- sulphuric solution of tin have been previously mixed, to make the liquor boil, turning the cloth as usual through it, by the winch, for a quarter of an hour ; then turning the cloth out of the liquor, to put into it about four pounds of cochineal, and two pounds and a half of quercitron bark in powder, and having mixed them well, to return the cloth again into the liquor, making it boil, and continue the ope- ration as usual until the colour be duly raised, and the dying liquor exhausted, which will be the case in about fifteen or twenty minutes ; after which, the cloth may be taken out and rinced as usual. In this way the time, labour, and fuel, necessary for filling and heating the dying vessel a second time, will be saved; the operation finished much more speedity than in the common way ; and there will be a saving of all the tartar, as well as of two-thirds of the 486 PHILOSOPHY OF cost of spirit, or Ritro-rnuriatic solution of tin, which for dying 1001b. of wool, commonly amounts to 10s.; whereas, Sib. of the murio- sulphuric solution will only cost about 3s. There will be, moreover, a saving of at least one- fourth of the cochineal usually employed, (which is generally computed at the rate of one ounce for every pound of cloth,) and the colour produced will certainly not prove inferior in any respect to that dyed with much more expence and trouble in the ordinary way. When a rose- colour is wanted, it may be readily and cheaply dyed in this way, only omitting the quercitron bark, instead of the complex method now practised of first producing a scarlet, and then changing it to a rose by the volatile alkali con- tained in stale urine, set free or decomposed by pot-ash or by lime : and, even if any one should still unwisely choose to continue the practice of dying scarlet without quercitron bark, he need only employ the usual proportions of tartar and cochineal, with a suitable quantity of the murio-sulphate of tin, which, whilst it costs so much less, will be more effectual than the dyers' spirit.* * The murio-suiphate of tin here recommended, is now em- ployed by the dyers in many parts of England, particularly in Yorkshire and Lancashire, though many of them do not know how, or with what acids it is prepared. A considerable distiller *A a^ua-fortis, and of muriatic acid, who also prepares solutions PERMANENT COLOURS. 487 Several hundreds of experiments warrant my assertion, that at least a fourth part of the cochineal generally employed in dying scarlet, may be saved by obtaining so much yellow as is necessary to compose this colour from the quercitron bark ; and indeed nothing can be more self-evident, than that such an effect, ceteris paribus, ought necessarily to result from this combination of different colouring matters, luited to produce the compound colour in ques- tion. Let it be recollected that the cochineal crimson, though capable of being changed by the acid of tartar towards the yellow hue on one hand, is also capable by different means of being changed towards a blue on the other, and of thereby producing a purple without indigo or any other blue colouring matter : yet I am confident that of tin in large quantities, informs me that he is in the practice of selling this preparation of that metal, under another denomi- nation, and that it is chiefly employed to dye the most vivid and beautiful yellows from quercitron bark. It has also been of late used to dye scarlet with a preparation called lac lake, made (in the East Indies) from the stick lac, to be noticed in my next chapter. Mr. Hawker (near Stroud, in Gloucestershire,) lately men- tioned at p. 454, told me, in 1795, soon after the publication of my first edition, that he had prepared the murio-sulphate of tin, according to my direction, and found it answer the purpose for which it had been recommended by me. 488 PHILOSOPHY OF nobody would believe a pound of cochineal so employed, capable alone of dying as much cloth, of any particular shade of purple, as might be dyed with it, if the whole of its colouring matter were employed solely in furnishing the crimson part of the purple, whilst the other (blue) pare thereof was obtained from indigo. To say that a pound of cochineal alone could produce as much effect or colour as a pound of cochineal ami a pound of indigo together, would be an improbability much too obvious and pal- pable for human belief; and there certainly would be a similar improbability in alleging, that a pound of cochineal, employed in giving another compound colour (scarlet), could alone produce as much effect as a pound of cochineal and a pound of quercitron bark, when the co- lour of this last was employed only in furnish- ing one of the component parts of the scarlet, for which a considerable portion of the colour- ing matter of the cochineal must otherwise have been expended, which certainly happens in the new mode of dying scarlet, because the colour produced with an addition of the quer- . citron yellow inclines no more towards a yellow, than the scarlet produced by yellowing a part of the cochineal colour in the usual method with tartar. I retain, therefore, at this moment, as much confidence as I ever had in the reality PERMANENT COLOURS. 48.9 and importance of my proposed improvements in this respect.* The scarlet composed of cochineal crimson and quercitron yellow, is moreover attended with this advantage, that it may be dyed upon wool and woollen yarn, without any danger of its being changed to a rose or crimson, by the process of fulling, as always happens to scarlet dyed by the usual means. This last being in fact nothing but a crimson or rose colour, yel- lowed by some specific or particular action of the acid of tartar, is liable to be made crim- son again by the application of many chemical agents, (which readily overcome the changeable yellow produced by the tartar,) and particularly by calcareous earths, soap, alkaline salts, &c. But where the cochineal colouring matter is applied and fixed merely as a crimson or rose colour, and * Of the benefit which I formerly expected to obtain by employing pot-ash or soda to extract a part of the cochineal co- lour, which water alone did not appear capable of extracting, it must be remarked, that J have some time since convinced myseli of its being an illusion j for, by repeated trials, I have found that the solid parts of powdered cochineal remaining after it has been boiled with the solution of tin and tartar, as in the common dying process, yield no colour worthy of notice, upon the appli- cation of pot-ash ; the solution of tin and tartaric acid, enabling the water to extract the colour sufficiently ; so that in truth there is no such waste of cochineal colour as I had supposed, in the usual way of employing that drug. 4 DO PHILOSOPHY OF is rendered scarlet by superadding a very perma- nent quercitron yellozv, capable of resisting the strongest acids and alkalies, (which it does when dyed with solutions of tin,) no such change can take place, because the cochineal colour having never ceased to be crimson, cannot be rendered more so, and therefore cannot suffer by those impressions or applications which frequently change or spot scarlets dyed according to the present practice.* There is also a singular property attending the compound scarlet dyed with cochineal and quer- citron bark; which is, that if it be compared with another piece of scarlet dyed in the usual way, and both appear by day-light exactly of the same shade, the former, if they be afterwards compared by candle-light, will appear to be at least several shades higher and fuller than the latter; a circumstance of some importance, when it is considered how much this and other gay colours are generally worn and exhibited by * MM. Thenard and Roard, in their " Memoire sur les mor- dants employes dans la teinture," observe, that ever since the dis- covery of scarlet, its liability to become crimson has been eomplained of without any attempt to ascertain and obviate the cause of that defect. In making the latter part of this observa- tion, they must surely have forgotten, or never have been madt acquainted with this part of my publication, which had preceded their Memoir sixteen yeare. PERMANENT COLOURS. 491 candle-light during a considerable part of the year. To illustrate more clearly the effects of the murio-sulphuric solution of tin with cochineal in dying, I shall state a very few of my numerous experiments therewith; observing, however, that they were all several times repeated, and always with similar effects. 1st. I boiled one hundred parts of woollen cloth in water, with eight parts of tke murio- sulphuric solution of tin, during the spa< e of ten or fifteen minutes ; I then added to the same water four parts of cochineal, and two parts and a half of quercitron bark in powder, and boiled the cloth fifteen or twenty minutes longer; at the end of which it had nearly imbibed ail the colour of the dying liquor, and received a very good, even, and bright scarlet. Similar cloth dyed of that colour at the same time in the usual way, and with a fourth part more of cochi- neal, was found upon comparison to have some- what less body than the former; the effect of the quercitron bark in the first case having been more than equal to the additional portion of cochineal employed in the latter, and made yel- low by the action of tartar. 2d. To see whether the tartrite of tin would, besides yellowing the cochineal crimson, contri- bute to raise and exalt its colour more baa the murio-sulphate of that metal, I boiled one ■HO ■i 492 PHILOSOPHY OF hundred parts of cloth with eight parts of the murio-sidphuric solution, and six parts of tartar, for the space of one hour; I then dyed the .cloth, unrinced, in clean water, with four parts of cochineal, and two parts and a half of quercitron bark, which produced a bright aurora colour, because a double portion of yellow had been here produced, first by the quercitron bark, and then by the action of tartar upon the cochineal colouring matter. To bring back this aurora to the scarlet colour, by taking away or chang- ing the yellow produced by the tartar, I divided the cloth whilst unrinced into three equal parts, and boiled one of them a few minutes in water, slightly impregnated with pot-ash ; another in water with a little ammonia ; and the third in water containing a very little powdered chalk, by which all the pieces became scarlet; but the two last appeared somewhat brighter than the first, the ammonia and chalk having each rosed the cochineal colour rather more advantageously than the pot-ash. The best of these, however, by comparison, did not seem preferable to the com- pound scarlet dyed without tartar, as in the pre- ceding experiment ; consequently this did not seem to exalt the cochineal colour more than the murio-sulphate of tin ; had it done so, the use of it in this way would have been easy, without relinquishing the advantages of the quercitron yellow. PERMANENT COLOURS. 493 3d. I boiled ■ one hundred parts of woollen cloth with eight parts of the murio-sulphurie solution of tin, for about ten minutes, and then added four parts of cochineal in powder, which by ten or fifteen minutes more of boiling, pro- duced a fine crimson. This I divided into two equal parts, one of which I yellowed or made scarlet by boiling it for fifteen minutes with a tenth of its weight of tartar in clean water ; and the other, by boiling it with a fortieth of its weight of quercitron bark, and the same weight of murio-sulphuric solution of tin ; so that in this last case there was an addition of yellow co- louring matter from the bark, whilst in the former no such addition took place, the yellow necessary for producing the scarlet having been wholly gained by a change and diminution of the cochineal crimson or rose colour; and the two pieces being compared with each other, that, which had been rendered sagrlct. by an addition of quercitron yellow, was, as might have been expected, several shades fuller than the other. 4th. I dyed one hundred parts of woollen cloth scarlet, by boiling it first in water with eight parts of murio-sulphate of tin, and twelve parts of tartar, for ten minutes, and then add- ing five parts of cochineal, and continuing the boiling for fifteen minutes. This scarlet cloth I divided equally, and made one part crimson, by boiling it with a little ammonia in clean WHBHHV 494 PHILOSOPHY OF water ; after which I again rendered it scarlet, by boiling it in clean water, \rith a fortieth of its weight of quercitron bark, and the same weight of murio-sulp'iate of tin; and this last, being compared with the other half, to which no quer- citron yellow had been applied, was found to possess the most colour, as might have been expected. A piece of the cloth, which had been dyed scarlet by cochineal and quercitron bark, as in the first experiment, being at the same time boiled in the same water with ammonia, did not become crimson, like that dyed scarlet with- out the bark. In this way of compounding a scarlet from cochineal and quercitron bark, the dyer will at all times be able, with the utmost certainty, to produce every possible shade between the crim- son and yellow colours, by only increasing or diminishing the proportion of bark. It has, indeed, been usual at times when scarlets, ap- proaching nearly to the aurora colour, were in fashion, to superadd a fugitive yellow either from turmeric, or from what is called young fustic (rhus cotinus); but this was only when the cochineal colour had been previously yellozvcd as much as possible by the use of tartar, as in the, common way of dying scarlet ; and therefore that practice ought not to be cm- founded with my improvement, which has for its object to preclude the loss of any part of the PERMANENT COLOURS. 4'Ji cochineal rose or crimson, by its conversion towards a yellow colour, which may be so much more cheaply obtained from the quercitron bark. By sufficient trials, I have satisfied myself that the cochineal colours, dyed with the murio-sul- phuric solution of tin, are in every respect at least as durable as any which can be dyed with any other preparation of that metal ; and they even seem to withstand the action of boiling •oap suds somewhat longer, and therefore I cannot avoid earnestly recommending its use for dying rose and other cochineal colours, as well as for compounding a scarlet with the quercitron bark. Having ascertained about the time of the publication of my first edition of this volume, that the red colour afforded by madder, might be greatly exalted and brightened by employing it with themurio-sulphate of tin, and indeed, with thenitro-muriateandthemuriateof that metal; (in- stead of alum) and that the lively yellowish red so produced, w&sexti'emely durable, it occurred to me, that there might be an advantage at least for ordi- nary scarlets, in substituting the madder for the quercitron bark, to compose ascarlet with cochi- neal, on the principle before explained ; because the former might be made not only to supply theyelluzv part of the scarlet, but also a portion of red, in aid of the cochineal colour, without perceptibly detracting from the vivacity of the ^■■■■■H 496 PHILOSOPHY OF latter; — with this expectation, I soon after made a great number of experiments, which fully answered my expectation, and proved by their general results, that cloth prepared by boiling the usual time with murio-sulphate of tin, (the acids not being saturajteel by the metal) and without tartar, and afterwards dyed with co- chineal and the finest Zealand madder, in the proportion of from two to three or even four pounds of the latter, with one of the former, might be made to acquire a good scarlet, with a saving of one fourth or one fifth of the cochi- neal, which would have been necessary to pro- duce it alone. When more of madder than the proportion just mentioned was employed, the colour, if contrasted with a very fine scarlet, ap- peared to incline towards a yellowish brown tint, though, to common eyes, this would be hardly perceived without such contrast. It must, however, be admitted, that for scarlets which are intended to excel and vie with those of Mr. Nash or his successor, it would be advi- sable to employ cochineal alone, or with the quercitron yellow instead of the madder red, cheapness being for them of less importance than beauty of colour. But for ordinary scar- lets, I am convinced it may be employed as jest mentioned, without any perceptible degradation of the colour, and with a considerable diminu- tion of ex pence. PERMANENT COLOURS. 497 I have thus freely given the results of a mul- titude of experiments, on which I have ex- pended money, with much more of time and meditation ; and though some years may elapse before the truth and importance of what I here offer are fully recognized, I am confident this will happen sooner or later ; and by putting it into every one's power to bring my ideas to the test of experience, I shall have at least done my duty.* I had not particularly directed my attention to the dy'mg of scarlet, until the year 1786, when no person, so far as I have been able to discover, had ever attempted to ascertain the effects of any solution or preparation of tin, excepting that with the nitric or nitro-muriatic acids upon the colouring matter of cochineal ; and I shall therefore state the results of nume- rous experiments which I have since made, with that metal, differently combined, and at various degrees of oxidation, omitting all de- tails respecting the proportions, and modes of conducting the dying operations, which are to be understood as having been conformable to * A portion of yellow colouring matter, obtained either from the quercitron bark or the rhus cotinus, is now (1812,) very generally employed in this country with cochineal, for dying scarlet ; not indeed, without tartar, but with a smaller quantity than that which is employed in other countries, and which was formerly employed in this. k k 4f)8 PHILOSOPHY OF the common practice, where nothing is men- tioned to the contrary. Woollen cloth, dyed with cochineal and pure nitrate of tin recently prepared, produced a fine crimson, and this, hoiled in the same liquor with tartar, was changed to a good scarlet. A similar, but rather better effect was produced by tin dissolved immediately in a mixture of aqua-fortis and tartar. The scarlet given by this tartaro-nitrate of tin appeared highly beau- tiful. Tin put into aqua-fortis, with a considerable portion of refined sugar, afforded a very thick adhesive solution, which assumed a blackish brown colour, like that of burnt sugar, and be- ing tried as a mordant in dying, it w T as found in- capable of fixing the cochineal or any other co- lours. The tin in this state did not seem fitted • to combine with the fibres of the cloth, and the sugar had manifestly suffered a kind of combus- tion, having probably in this case produced, upon the tin, as it does with indigo, (see p. £217,) a deoxygenating effect. Spirit of wine, put with tin into aqua-fortis, also rendered the solution unfit to serve as a mordant, and, as I conclude, by a similar deoxygenation. Tin, granulated and calcined with an equal quantity of salt-petre in a red-hot crucible, be- ing thrown into water, afforded a milky solu- tion, tasting very sensibly of the alkaline part of the salt-petre, and evidently suspending a PERMANENT COLOURS. 499 considerable portion of the metallic calx. Cloth boiled in water with some of this solution, then rinced, and dyed with cochineal, took a crimson, inclining to the purple; and this, bftijed in the same liquo* with tartar, was changed to scar- let. Having poured two pounds of aqua-fortis, with an equal weight of water,, upon a large quantity of granulated tin, and left them toge- ther during the three summer months of 17£/0, I afterwards found near a pound of the calx of tin collected in solid lumps at the bottom of the glass vessel. This being separated and dried, some of it was finely powdered and thoroughly washed ; and being put with an equal weight of cochineal into water, I boiled cloth therein, which took a full equal erimson, somewhat de- ficient in brightness.* Tartar being added to the liquor, and the cloth farther boiled therein, it acquired a good scarlet. Lemon juice used, instead of tartar, produced the like effect. By substituting caustic volatile alkali for tartar and lemon juice, a crim- * The calx or oxide of tin employe ! for this experiment, was some of that which is mentioned at pages 'i\4 and 215, as having efficaciously ^oxygenated indigo : consequently it was far from being in the state of a peroxide, or at the maximum of oxygenation ; in which state I consider tin as being inca- pable of producing with cochineal any thing more red or ele- vated than an orange, or a salmon colour, at the most. K k g 500 PHILOSOPHY OF son, greatly inclining to purple, was produced. The oxide of tin, therefore, does not act in all cases merely as suck, but its effects often depend on triple, quadruple, and sometimes even more complex combinations, in which different saline and other parts of the compound remain perma- nently united, at least where the shades of co- lour depending on them are found permanent. It is thus that sea-salt, and other purely saline matters, which, having no earthly or metallic basis, cannot become the basis of any adjec- tive colour, produce lasting effects in modi- fying and varying the shades of different co- lours.* It must, however, be observed, that though the calx of tin, just mentioned, was, after being thoroughly washed and dried, capable of dying a crimson on woollens with cochineal, and a scarlet, where either tartar, lemon juice, or Quercitron bark were added, it would not per- manently combine with, or become the basis of, * Hellot describes, at p. 234, a " Cramoisi de Languedoc,' which was dyed with cochineal upon cloth prepared as for the scarlet dye, excepting, that instead of tartar, sea salt was added to the solution of tin j which addition caused the colour to in- cline towards the purple or dark crimson ; an effect which all the mineral acids seem to produce with cochineal, when neu- tralized by soda, and more especially by potash ; and therefore, in making the common dyers' spirit, when nitric and muriatic acids, perfectly free from the sulphuric, can be had, it would be better to employ the muriatic acid instead of sea salt, especially when very bright scarlets are wanted. PERMANENT COLOURS. 501 these colours upon cotton ; and indeed, on woollen it was only the finer particles of the calx which really combined with the colouring matter and the wool, the grosser being always distinctly found at the bottom of the dying vessel ; and when I attempted to impregnate woollen cloth with this oxide of tin only by boiling them together, I always found, on rinc- ing the cloth, and endeavouring to dye it with cochineal in a different vessel or bath, that the oxide had not penetrated or united with the wool, so as to afford a basis for raising and fixing the colour, it being necessary for this purpose, that both the oxide and the colouring- matter should be mixed together in the dying vessel, and exert their mutual attractions for and upon each other, before they could be properly taken up by the cloth ; and this was done better after they had been previously mixed and left to- gether for several hours. One ounce of the calx of tin before men- tioned, unwashed, being dissolved in three ounces of muriatic acid, and woollen cloth being dyed with a tenth of its weight of this solution, and a twentieth of cochineal, it took but a very languid colour. The oxide of tin, (probably from too much oxidation) being immediately decomposed upon its intermixture with water, and manifesting very little disposition to pe- netrate or combine with the fibres of the wool ; so that after long boiling, a great ■HHHBBBHHB 502 PHILOSOPHY OF part of it, and of the colouring matter, remain- ed suspended in the dying liquor, as in my second experiment at the dye-house of Messrs. Goodwin and Co. Cochineal with a solution of tin by muriatic acid onty, dyed a beautiful crimson or rose co- lour; and with a solution of that metal, by a mixture of tartar and muriatic acid, a beautiful scarlet. Cochineal, with tin dissolved by a mixture of muriatic, and pyroligneous acid, produced a dark crimson ; and with tin, and a little manganese dissolved in muriatic acid, it produced a very bluish crimson. Cochineal, with tin dissolved by muriatic acid and borax mixed, dyed a very good crimson. Cochineal, with tin calcined by the long con- tinued action of sulphuric acid, dyed a salmon colour; and with a recent solution of tin, it pro- duced a reddish salmon colour, inclining a little to the crimson. A like colour was produced with tin dissolved by equal parts of sulphuric and nitric acids mixed. Oil of vitriol, having been poured upon tartar and granulated tin, the mixture immediately be- came black, by the action of the sulphuric acid upon the carbonic basis, which, with hydrogene and oxygene, are the constituents of tartar. Cloth, dyed with a tartaro-sulphuric solution of tin thus made, and cochineal, took an aurora colour. PERMANENT COLOURS. 503 Tin dissolved by the pure aeid of tartar, sepa- rated from its alkaline basis, (by the means usually employed for that purpose,) dyed with cochineal on cloth a very lively and beautiful scarlet, inclining a little to the orange. A similar colour was produced by water saturated with cream of tartar, in which granulated tin had been kept six weeks. Tin may be readily dissolved by pure citric acid, and more slowly by lemon juice ; and the solution newly made, dyes, with cochineal, a most beautiful scarlet, inclining, like the pre- ceding, a little to the aurora. Indeed, I have repeatedly found, that the citric acid with tin, acts at least as efficaciously as that of tartar in yellowing the cochineal crimson. Nothing can exceed the beauty of scarlet dyed with the ci- trate of tin, and if it were not too costly, this so- lution would deserve the preference of every other for dying scarlet. Granulated tin, dissolved by strong vinegar, acquired a milky appearance with a very par- ticular, and somewhat of an unpleasant smell ; and with cochineal it dyed cloth of a scarlet, inclining a little to the rose colour. Tin dissolved by the pyroligneous acid pro- duced with cochineal a colour between the scarlet and rose colour. Phosphoric acid produced a permanently transparent and colourless solution of tin, which, 50 1 PHILOSOPHY OF with cochineal, dyeci a bright yellowish scar- let. Tin, dissolved by fluoric acid, produced with cochineal a very bright scarlet. In addition to this account of experiments made previously to my first publication on this subject, I will mention a few of those which I have since made. Tin having been dissolved by a direct mixture of pure nitric and muriatic acids, in equal pro- portions, the former of the specific gravity of 1500, and the latter of 1 170, this solution, with cochineal and the common allowance of tartar, produced a very bright lively scarlet. Tin, having been dissolved by a similar mix- ture, with an addition of sulphuric acid, equal to one fourth of the nitric, and the solution being afterwards employed with cochineal and tartar, as in the last-mentioned experiment, a salmon colour only was produced. Tin, being dissolved in a mixture similar to that last-mentioned, but with this difference, that before the sulphuric acid was added, tartar, amounting to three times the weight of the sul- phuric acid, had been mixed with the nitric and muriatic; and this solution being employed with cochineal, and a little more tartar, a good scarlet was produced ; the tartar which had been added before the sulphuric acid having, by its alkaline part, neutralized the vitriolic acid, and obviated PERMANENT COLOURS. 505 the evil produced by the latter, in the preceding experiment. Having precipitated the oxide of tin (by- soda) from the common dyers' spirit, or nitro- muriate thereof, and subjected this to the action of sulphuric acid, I found it incapable, with co- chineal, of dying any colour more elevated than the orange. After this account of the effects of the oxides of tin, in various states and combinations, when applied with cochineal on wool or woollen cloths, it is, I think, expedient for me to add a few other observations concerning those particu- lar solutions of that metal, which are most fre- quently employed as mordants in dying, and the means by which they may be most advantage- ously obtained and employed. It can hardly be necessary to premise, that for these solutions, the purest tin should always be selected; such as that of Malacca; next to which is that of Banca ; and after it, the tin of Mexico, is considered as most pure. In regard to the tin mines of Europe, those of Cornwall afford tin of the greatest purity ; and after these, the tin of Bohemia is considered as preferable to that of Saxony. The most frequent adulterations of tin are produced by intermixtures of arsenic, lead, cop- per, and iron. The first of these renders tin whiter and more brittle; the others give it shades of grey, which are dark, when either of SB MR 506 PHILOSOPHY OF the two last bears a considerable proportion. The means of detecting these adulterations have been mentioned by most of the systematic che- mical writers. The presence of either iron or copper in tin, may be readily ascertained by dissolving a little of it in pure muriatic acid, and dropping the solution into a prussiate of lime, which will afford a precipitate more or less blue, if the tin contains iron ; and if it con- tains copper, a reddish bronze precipitate. When pure colourless nitric and muriatic acids are mixed in quantities not very disproportion- able, the former of these acids will be partially decomposed, with an exhalation of oxymuriatic acid, and a production of nitrous gas ; but this last will remain for some time dissolved by the mixed acids, and give the mixture a red colour ; and if granulated tin be added to the mixture, it will soon destroy this red colour, by expelling the nitrous gas ; and will, moreover, cause a farther decomposition of the nitric acid, by combining with its oxygene ; which combina- tion renders it susceptible of a more speedy dis- solution by the muriatic part of the compound. Dyers, however, do not commonly produce their aqua-regia by a simple mixture of the nitric and muriatic acids, but by adding to single aqua-fortis a portion of sea salt; and in so doing they (without knowing it) obviate the injury which the small proportion of sulphuric acid PERMANENT COLOURS. 507 frequentl} 7 contained, either in aqua-fortis or in muriatic acid, would produce, if allowed to act upon tin in conjunction with nitric acid; as I have found by numerous experiments. But in this way of producing a nitro-muriatic acid, the soda contained in the sea salt, by combining with the sulphuric acid, and forming Glauber's salt, renders the latter incapable of any hurtful action ; at least, if there be not more of it than the soda of the sea salt can neutralize ; and wlien this happens, the addition of a little salt petre, which Hellot and others have thought beneficial, (without assigning any reason for thinking so), would render this excess of sul- phuric acid harmless, by affording potash to form with it a sulphate thereof. By modern chemists, the solution of tin, when made by nitro-muriatic acid, is supposed to contain, or afford, only a muriate of that me- tal ; it being assumed, that the nitric aeid suffers a complete decomposition, and that its oxygene is all, either expended to oxidate the metal, or exhaled with the nitrous gas. I believe, how- ever, that the nitric acid is never completely de- composed, by this operation ;* at least I have * The proportion of either sea salt or muriate of ammonia, employed by scarlet dyers in making their ordinary solution of tin, is by much ttro small to permit us to believe the result of that process to be merely a muriate. Hellot, who prefers a muriate of ammonia to sea salt, prescribes as the test propor- 508 PHILOSOPHY OF never found any solution of tin made by nitro- munatic acid, which did not differ considerably in its sensible qualities, and also in its effects, as a mordant, with cochineal, &c. from a solution of that metal by pure muriatic acid. I attach no importance to the straw, or amber, colour of th olution of tin, commonly employed by the dyers, while the muriate of tin is colourless ; be- cause the colour of the former certainly results, from the neutral salts which it holds dissolved : for, when the solution is made by a direct mix- ture of pure nitric and muriatic acids, it is as colourless as if it had been made by muriatic acid only ; but in this case, it invariably exhales, and for a long time, the odour of ni- trous gas, even when the acids were mixed in equal proportions ; a certain proof, that the nitric acid was at most but partially decomposed. It has, moreover, several other peculiarities, tion, only half as much of it in weight, as of the metal em- ployed ; and Dambournay used a proportion smaller than Hel- lot's, which, however, is I believe, that of most of the dyers, whether they employ sea salt, or sal ammoniac ; and certainly neither of these could afford muriatic acid sufficient to dissolve twice its weight of tin, as it must do, if the solution so produ- ced were merely a muriate of that metal. I have sometimes employed a solution of tin, made by a diluted, but very pure nitric acid, with an addition of muriate of ammonia, amount- ing to no more than one eighth of the weight of metal so dis- solved, which could have contained but a small proportion of muriate of tin ; but this solution in a very few days, will lose its transparency, and be capable of producing only orange salmon colours. PERMANENT COLOURS. 509 particularly that of not affording crystals by evaporation, like the muriate of tin, and also that of becoming both opaque and gelatinous by keeping, which does not happen to the mu- riatic solution ; nor does it, when used in excess, injure the texture of wool, so much as an equal excess of the latter. One cause of this last peculiarity, or differ- ence, may depend upon the production of am- monia, whenever tin is dissolved by nitto-muri- atic acid. Berthollet obtained satisfactory evi- dence of the reality of this production, even when the aqua-regia was made by a direct and gradual mixture of the pure nitric and muriatic acids; and he considers it as being a fact, which may enable us to understand, why in dying there is less difference than might be expected, between the effects of a solution of tin, made by this direct and simple mixture of the- two acids, and those of a solution made by aqua-fortis with an addition of muriate of ammonia. Besides this production of ammonia, M. Ber- thollet supposes, that another occurs in the dying operation, whenever the heat is near the boiling point: and thai, by this, and the former produc- tion of ammonia, the acidity of the solution of tin is greatly diminished; which, as he thinks, will enable us to understand why the cloth is not injured by the common process for dying scarlet, though the nitric acid of itself, would, even when much diluted, produce hurtful effects 9SR SHEW iw mm 510 PHILOSOPHY OF upon it ; and be also considers this as explaining the cause of the injury which the cloth suffered in my first experiment at the dye house of Messrs. Goodwin and Piatt.* Having ascertained, as is mentioned in the note to p. 462, that a muriate of tin, containing only halt the quantity of that metal, which the acid might have been made to dissolve, had operated as efficaciously as an equal quantity, containing twice as much tin, and in some respects with a better effect, in the dying of scarlet, I was led by this and other facts to suspect, that a much smaller proportion of tin than that which the dyers commonly dissolve in their nitro-muri- a tic acid, would produce equally beneficial effects. And, to ascertain the truth on this point, I put two drachms of powdered muriate of ammonia* into three ounces of strong nitric acid of the spe- cific gravity of nearly 1500; and, having diluted this mixture by adding to it six ounces of water, I made it gradually dissolve fine granulated tin, until the acid was completely saturated; when * After mentioning the neutralizing, or saturating effect of the ammonia, formed and acting, as has been just stated, M. Bjr- thollet adds " on trouve encore clans cette action saturante Im- plication d'une observation de Bancroft. II vou loit substituer dans la teinture del'ecarlate, 1c muriate, d'Etain,au nitro-muria:e ; niais, il en fall at une plus grande proportion, et la laine se trcvee fort deterioiee. Dans celte operation, il ne pouvait se formci de 1'am moniaque, et l'acide muriatique, quo affaiblit facilemen la laine, exenjait sur elle toute sou action." Eleraens, &c. tora.L p. 385. PERMANENT COLOURS. 511 I found that the tin so dissolved amounted in weight to a little more than half the weight of the nitric acid. On the same day I made another solution, similar in every respect to the first, excepting only that the tin dissolved therein weighed only half as much ; and with these solu- tions,! made several experiments, the two following days, which were afterwards repeated, and in all of them I found, that the solution containing only half' of the tin, which might have been dissolved therein, produced with cochineal, colours which at least were in every respect as good as those resulting from an equal quantity of the satu- rated solution ; and after I had ascertained by several trials the smallest proportion of the half saturated solution of tin which was necessary to produce a good scarlet upon a given weight of broad-cloth, 1 found, that the saturated so- lution would only produce an inferior colour, when (on account of its greater proportion of tin) I diminished the quantity even but an eighth part. I conclude, therefore, that nearly one half the tin, which the scarlet dyers commonly dis- solve with aqua-fortis, and a little sea salt, to make what they denominate spirit, is wastefully employed ; a fact which, considering the increased price of tin, may, by proper attention, produce a saving of very considerable importance. It appears to me, indeed, from a variety oY con si- derations, that a proportion, and not a small one, of superfluous or unsaturated acid, is highly 512 PHILOSOPHY OF useful to enable the basis, or oxide of tin, actu- ally employed, to produce its utmost and best effect, by conveying it more copiously and thoroughly, or with greater penetration, into the substance of the wool or cloth. For, with this superfluous acidity, I have repeatedly made the scarlet dye penetrate completely the innermost parts of the cloth, without any of the meanis mentioned in a note at p. 91, as having been employed by Mr. Nash, and his successor, for this purpose, and without any other means ex- cepting the use of a superfluous acidity; and I think one of the benefits resulting from the em- ployment of tartar, either with alum or with the solutions of tin, is that of furnishing a portion of uncombined acid, in addition to that which ac- companies the alluminous or metallic basis ; which basis, being thereby enabled to penetrate wool or cloth more intimately, afterwards attracts the colouring matter more copiously and thoroughly. It must however be observed, that this superfluity of acids may be too great ; and that it should never be employed in the same bath, or liquor, which contains the cochineal, but always in the previous boiling ; since all acids, when present in a large proportion, weaken or render latent the colour of that insect. In regard to the muriate of tin, I may be allowed to premise, that the muriatic acid, in its liquid state, is necessarily combined with water; and that the proportion of the latter, in which PERMANENT COLOURS. 513 the acid is best preserved, and most commonly sold, is such as to render its specific gravity equal to 1 l60, or at most 1 170; and that, when of the latter degrees of .strength, three pounds of it av ill dissolve nearly one pound of granu- lated tin, with the assistance of a sand heat. When pure, the muriatic acid is colourless; though it frequently exhibits a light straw colour, resulting, as is supposed, from a small portion of iron dissolved by it: but this disap- pears almost instantaneously, if a little tin be dropped into the acid. The dissolution of tin by this acid, is always accompanied by a copious emission of bub- bles, which, excepting a little of the acid es- caping at the same time, appear to consist of lii) dm gene, disengaged, as has been generally be- lieved, in consequence of a decomposition of the water previously united to the acid ; which decom- position is supposed to afford oxy gene sufficient to oxidate the metal, as far,as is necessary to render it soluble by the muriatic acid. Davy, however, in reviving the doctrine of Scheele, endeavours to maintain, that the muriatic acid itself contains hydrogene, which, by this operation, is set free, while that, which he supposes to be its elementary part, and which he denominates chlorine, dis- solves and combines with the metal. (See Phil. Trans, for 1810). Having already, in the introductory part of l 1 $11 PHILOSOPHY OF this volume, stated every thing which I mean to suggest, on this intricate subject, I shall pro- ceed to observe, that however the emission of hydrogene may be explained, it is attended with a considerable escape of muriatic acid, which carries with it a portion of the metal itself, as is manifested by the smell. Gay Lussac con- siders himself as having ascertained that tin, by being so dissolved, combines with 13,5 per cent, of oxygene ; and that, by making a current of aqueous vapour pass over the metal, in a red heat, a white oxide may be produced, similar to that which is formed by subjecting tin to the action of concentrated nitric acid, and which, according to his experiments, consists of 27,2 parts of oxygene to 100 of tin. (See Ann. de Chimie, torn. 80, p. I69.) Those who wish to dissolve large quantities of tin by muriatic acid, will find it advanta- geous to decompose the dry sea salt, by employ- ing sulphuric acid in the proportion of five parts of the latter to eight of the former; using the precautions which have been prescribed, by chemical writers : and, by collecting the muri- atic acid as set free in vapour, and conveying it ii '.ely into large receivers, containing grap ith a little water, to absorb the our, the heat constantly and gr?;c Ived by that absorption, will (as M,.Cba iffice to piornote asolutioa PERMANENT COLOURS. 515 of the metal 4 without any expence of fuel. (See Chiinie, applique* aux Arts. torn, iv, p. 182.) In this way, also, the loss of acid, and ol tin, by evaporation, may be in a great degree obviated; as indeed it may be when common muriatic acid is employed for this purpose, if the solution be made in tubulated retorts.* If muriate of tin, containing one- fourth of its weight of the metal, be sufficiently evaporated, it willaffordconsiderablymore than half itsweightof solid transparent crystals, which are the heaviest of*all the metallic salts ; but the evaporation is accompanied with a pungent disagreeable odour, produced by an intimate combination of muri- atic acid and tin, which is highly volatile; and, consequently, the bringing such a solution into a crystallized form, must be attended with a great loss, both of the acid and the metal. * Being at the bouse of Mr. Hawker, at Dudbridge, near Stroud, in Gloucestershire, during several of the last days of August, 1795, about 12 months after my first publication on this subject, that very estimable dyer informed me, that he had then lately begun to employ the muriate of tin for dying scarlet with good effect, and a considerable saving of expence in regard to the mordant} and he also shewed me the way in which his muriate of tin was prepared, which was, by putting large portions of ihe granulated metal into muriatic acid, contained in capacious, open vessels, and leaving it therein several weeks, assisted only by the ummer's warmth : a great evaporation and waste of acid una- voidably occurred, and the acid, as far as 1 could judge, was not more than half saturated ; which doubtless was an advantage. L 12 ^fl^^^^^^^^B BHHHB SHI 9Ni BMi 516 PHILOSOPHY OF Tin when first dissolved by muriatic acid, is supposed to be at the lowest degree of oxida tion, but if the atmosphere be allowed free ac- cess to the solution, it will constantly absorb and unite with an increased portion of oxygene; and Pelletier pretends, that in proportion as it docs this,- and becomes most odidated, it also becomes most etiicacious and useful as a mordant in dying.* But Ids experiments certainly do not warrant any such general inference; and the numerous trials which I have made of this metal as a basis, (with cochineal, quercitron bark, &c.) at various, and probably at all the possible degrees of oxidation,f have abundantly con- vinced mc, that the oxide of tin acts most power- fully in exalting and giving vivacity to colours, when it is hut little oxidated, and that every de- gree of oxygenation beyond a certain unascertain- ed number, tends to reduce or diminish the high * See Mem. et Observat. de Chimie. torn. i. i I am aware that modern chemists are disposed to consider tin as only susceptible of two stages or degrees of oxygenation^ the lowest called a protoxide, in which the metal contains about 13 per cent, of oxygene ; and the highestcalled peroxide, in which, according to some estimations, it is at about 24 oxygene to 76 of tin, and, according to others, at 28 to 72. I believe, however, that in my experiments, I have employed this metal at sevenl intermediate stages or degrees of oxydation, notwithstanding all that has been written, and particularly by Professor Be- zelius, on the determinate proportions in which the inorgau.c elements of nature aie supposed to unite. PERMANENT COLOURS. 517 red of the cochineal dye, and at the same time to make it incline to, or partake of, too much of the orange, so as only to produce, when highly oxi- dated, what I have denominated a salmon colour. Such is invariably, and in a remarkable degree, the effect of tin, when it has been subjected to the action of sulphuric acid alone, or in con- junction with the nitric; and also after it has been for some time rapidly dissolved by pure nitric acid but little diluted ; and it can hardly be necessary for me to add, that in all these cases the metal will have obtained a higher degree of oxygenation. Similar effects, though in smaller degrees, have been found to result from a variety of combinations by which the oxide of tin, < though less oxygenated than in the former, was yet too much so to produce its best effects. In stating as my opinion, that tin is most effi- cacious in raising and giving brightness to colours, when but little oxidated, I purposely avoided the word least, because my experiments do not war- rant me to say that colours are not as much exalted, and enlivened, by a muriate of tin, to which a little nitric, or a little sulphuric acid has been added, (after the solution was made) as by the muriate alone, when recently made; provided that only one of these acids be added; for both together would, as has already been observed, render the tin incapable of producing, with cochineal, any thing more elevated than a salmon or orange colour. But in attributing such effects 518 PHILOSOPHY OF to variations in the degrees of oxidation, at which tin is employed, 1 desire not to be under- stood as believing, that these alone operate, in producing differences in the shades of co- chme al colours, or that the several a<-i-is em ployed do not exercise a very considerable influence, in this respect, by their pe< uiiai pro- perties, independently of their effects m cxy- genating the metal itself. In concluding these observations concerning the muriate of tin, I beg leave to repeat, what has been already mentioned, that though it ceiv tainly acts more strongly than any other solution of that metal, in weakening the fibres of wool, especially when the acid is saturated by the metal, it may, when the latter is dissolved more sparingly, be employed with perfect safety, (and a considerable saving of cxpence) and more especially in conjunction with the usual proportion of cream of tartar ; and even with a cc> iderable proportion of sulphuric acid, which indisputably, though perhaps unaccountably, moderates this hurtful action of the muriate of tin,* as indeed every other acid seems to do. * A manufacturer whosupplies the Country dyers with not only the muriate, but ihe murio-sulphate of tin (recorome nded at p. 4S3,) -inures me, that to produce the latter he first prepares the muriate of tin, which he sells of two sorts j in oneof which the dis- solved metal amounts to a fourth, and in the other to a fifth part of the solution 3 and by gradually adding to either of these PERMA EOT COLOURS. «19 I have mentioned with approbation, between pages 385 and 392, the results of several ex- periments made, by MM. Thenard and Roard, to ascertain the effects produced on wool, by boiling it with the usual proportions of alum and tartar, and also with the usual proportions of the latter, and of the nitro-muriate of tin, as employed for the dying of scarlet ; and it seems proper that I should here notice some other pits of their " menwire," which relate more immediately to the production of this colour. " Scarlet, they say, is obtained by treating wool with determined proportions of cochineal, acidulated tartrite of pot-ash, and a highly oxy- dized solution of tin" " The operation is divided two-thirds of its weight of concent rated oil of vitriol, he produces a murio-sulphate of tin, in which, however, the acids are not more than half saturated; but, notwithstanding the great strength of these acids, the solution has net been even suspect- ed of producing any injury to cloth dyed with it; and the pre- parer of it asserts, that it produces the best effects after being kept several years. No length of time which has elapsed since it was first made and recommended by me, seems capable of diminishing its colourless transparency, which equals that of *he clearest spring-water ; a circumstance which seems not a little extraordinary, when we consider that sulphuric acid alone is speedily decomposed by tin ; sulphur being distinctly pre" duced, and the tin itself converted to a brownish calx, which subsides in a mass to the bottom of the vessel, in which th« decomposition has been effected. 520 PHILOSOPHY OF into two parts; the first taking up- an hour and a half, and the second half an hour:" " This division (they add) is necessary to produce a good colour, which would be weaker and more yellow if all the substances were mixed in the first operation and applied to the wool for two hours," by reason of the acidity of the bath, or dying liquor. " We obtain,"' say they, a con- trary effect when the mordants only areemployed in the first operation, and the cochineal is re- served for the second." They, however, contra- dict this last position, in another part of the same memoir, by asserting that wool, combined with the mordants in question, and dyed after- wards separately with cochineal only, will never become scarlet ; because this colour, as they allege, can only be produced by a cochineal bath, which is very acid " tres acide," " et qui en faisaut passer aujaune, le ton de la cochenille, donne alors tant d'eclat a cette couleur."* But the effect of tartar, which principally causes this approach to yellow, in the cochineal colour, may, as I have found by scores of experiments, be very well produced, together with that of the solution of tin, by the first boiling; and a very fine scarlet be afterwards dyed by the se- cond with cochineal alone, taking care only, when no tartar or tin is intended to be employed * See Ann. de Chirnie, torn, lxxiv. p. 290. PERMANENT COLOURS. 521 in the last operation with the cochineal, that a full proportion of them be employed in the first, and that their effects be not removed or dimi- nished by wrincing the cloth, between the first and second boilings. In regard to the incon- venience of dying scarlet by a single operation or boiling, I will only observe, in addition to what I have stated on that subject at p. 454, that where only a bare sufficiency of cochineal is employed, with affull proportion of the mor- dants, and especially of tartar, the colour, though very lively, will appear rather deficient in quan- tity, or body, because the cloth will not com- pletely exhaust the dying liquor of its colour, when the acids are in excess. This, however, will not ultimately be attended with any waste of colour, because dyers, by a succession of un- dyed pieces, know how to take up, and fully avail themselves of every thing left by a former operation. In regard to the high degree of oxida- tion of tin, which these gentlemen consider as necessary for producing a scarlet, I must con- clude, that they have been misled by the opinion of Pelletier on this subject, or that they have supposed the solutions employed by them to be much more oxygenated than they really were. Certainly I have produced, as I believe, more than one hundred times, scarlets as beautiful as can be any where found, by the recent, and lit- ■ mm pppp ■ pi^i ■ 522 PHILOSOPHY OF tic, perhaps least, oxidated muriate of tin, with only the usual proportions of tartar and cochi- neal ; and I have very often found myself una- ble to produce any thing better than an orange or a salmon colour, by solutions of tin, which certainly were highly oxygenated. Indeed, the dyers notoriously and universally consider their spirit, or nitro-muriatic solution of tin, as being unfit for their purpose, when it looses its trans- parency; an effect which indicates, and results from a greater degree of oxygenation in the metal.* In another part of their memoir, these gen- tlemen are pleased to say, that though the pro- cess for dying scarlet has long been known, no person has made any theoretical researches, con- cerning the phenomena which occur, when the solution of tin, cream of tartar, and cochineal, are made to act upon, or with each other, * I have said, at p. 508, that the straw or amber colour of the solution of tin, commonly employed by dyers, appeared to result from the neutral salts which it holds in solution. I have, however, since discovered that J was then misled by an experiment which ought to have been differently explained, and that this colour may be instantly either produced, or increas- ed, by adding a very little muriate of tin to the nitro-muriate of that metal ; the former, by being thus added, producing a de- composition of the nitric acid in the latter, and a disengagement of reddish nitrous gas, which occasions the colour, and affords an additional proof of my assertion, at p. 507, that the nitric acid is never completely decomposed, in the dyers' spirit, or nitro- muriate of tin. Permanent colours. 52S ' dans le traitement de la dissolution detain avec la cicme de tartre et lacochenille;" adding, that I, who (as they observe) have occupied myself with great, success in dying, have in- deed endeavoured to explain what occurs in the formation of the scarlet colour; but that as my opinion does not seem to them to have been founded upon any experiment, they are in tit led, notwithstanding that opinion, to consider the question as being no more decided, than it was before the publication of my work.* As these gentlemen distinctlyassert, in this their memoire, that the production of a scarlet colour, (instead of arose or crimson) by the common process, is due to the action of the acid of tartar, and as this is precisely what I had distinctly asserted and maintained sixteen years before, 1 must understand them not as intending to controvert my opinion, but to represent it as one which, though correct, had been formed or hazarded, without any experiment or evidence; and that, therefore, what I had done, was of little or no * " Le Docteur Bancroft, qui s'est occupe avec beaucoup desuc PERMANENT COLOURS. B29 riate of alumine) dyed a crimson, differing but little from that produced with common alum. The silicated alkali of Dr. Black, or powdered flints, dissolved by a violent heat, in a crucible, w r ith pure caustic alkali or pot-ash, was tried as a basis for the cochineal colour. At first, the fibres of the cloth did not seem to have sufficient attraction for the siliceous basis and the colour- ing matter, to attach and fix them properly ; but on adding a little sulphuric acid, so as to de- compose and neutralize a part of the alkali, which had dissolved and was combined with the siliceous earth, the colour took freely, and rose to a full, rich, pleasing purple, in which the red or crimson predominated considerably ; and this colour afterwards proved sufficiently du- rable. In regard to alkaline earths, (so called) I found that lime water with cochineal dyed a purple, which took but slowly, and required long boil- ing. That sulphate of lime, or lime dissolved by sulphuric acid, dyed a full dark red. That nitrate of lime, or lime dissolved by nitric acid, dyed a lively red, approaching to scarlet. And that muriate of lime with cochineal dyed a purple. Cloth boiled in water with nitrate of lime, and then dyed in clean water with cochineal and tin, M m 530 PHILOSOPHY OF dissolved by aqua-fortis and tarter mixed, re- ceived a good scarlet. Cloth boiled with carbonate of lime and alum, and then dyed in clean water with cochineal, took a good crimson, inclining to the bluish shade. Sulphate of barytes, or ponderous spar, not being soluble in water, was not tried. But muriate of barytes, employed as a basis for the cochineal colour, dyed a good lively purple ; and Nitrate of barytes dyed a colour nearly simi- lar, but inclining a little more to the crimson. Magnesia alone did not combine sufficiently with the fibres of cloth, and with the colouring matter of cochineal, to serve as a basis for dye- ing- But magnesia dissolved by sulphuric acid, (forming Epsom salt,) dyed a lively purple with cochineal, though it took but slowly, and required long boiling. The acetate of magnesia dyed a lilac colour. Strontites, or strontia. earth, dissolved by muriatic acid, and employed as a mordant with cochineal, produced on woollen cloth an orange colour. It appears, therefore, that besides the me- tallic oxides and solutions, the simple earths, so far as they have been tried, and all the alkaline, are capable of serving as bases of the cochineal PERMANENT COLOURS. 531 colouring matter ; though not with equal advan- tage, and we shall hereafter find, that they are capable of doing the same to other adjec- tive colours ; a fact never before ascertained, though of great importance, as well in respect of the practical improvements which it may produce, as of the general principles and con- clusions to which it may lead us on this sub- ject.* I have repeated nearly all the foregoing ex- periments with silk, instead of wool, and gene- rally with effects less advantageous. Cochineal, indeed, with the aluminous basis, dyes the crim- son colour as well and as durably on silk as on wool, and the modes of producing a very lasting- crimson by these means are well known. But the oxides or solutions of tin tend to diminish the shining glossy appearance of silk, and, there- fore, when applied to it do not reflect the co- chineal colour with the same degree of fulness and lustre as upon wool ; and it has, therefore, been found impossible to dye a good lively scar- let on silk by the means which communicate that colour to wool. * I have found that cochineal has so much affinity for wool, that if the latter be boiled with a portion of sulphuric acid suffi- ciently diluted, and afterwards dyed with cochineal, it will, without any other basis,, take a red colour, capable of bearing exposure to the sun and air for some weeks, though fewer than if dyed upon a suitable basis. But cotton will take no colour in this way. M 111 2 jam ■ ■ m%mm&:: 532 PHILOSOPHY OF The late Moiis. Macquer, indeed, about the year 176*8, pretended to have discovered the means of dyeing a scarlet upon silk by a process which he published in the Memoirs of the Royal Academy of Sciences for that year. Accord- ing to that process, he began by dying the silk first of a yellowish orange colour, with an- notta applied in the usual way; then he soaked it for half an hour in a diluted solution of tin, made by a mixture of two parts of the nitric with one of the muriatic acid; after which the silk was taken out, moderately pressed, and rinccd in clean water, though he afterwards found it better to omit the rincing. To dye the silk, when thus impregnated with nitre-muriate of tin, be prepared a bath, by boiling from two to four ounces of cochineal and a quarter of an ounce of cream of tartar, for each pound of silk, some minutes in water; after which he added cold water, until the heat of the liquor was re- duced to what the hand could bear, and then pu; in the silk, and dyed it as usual, gradually rais- ing the heat of the dyeing liquor, so as at last to make it boil for a single minute. I have several times repeated this process, but always found the colour produced by it very inferior to the scarlets usually dyed on woollen cloth ; and M. Berthollet informs us, that this was also the case at the trials which Mr. Macquer himself made of his process at the dye- house of the Go belines ; and in truth there was nothing of an/ PERMANENT COLOURS. 533 importance in Mr. Macquer's supposed disco- very. It seems, indeed, to have been chiefly bor- rowed from a process published by Scbeffer, in 17.51 » excepting so far as relates to the colour first given with annotta, and excepting a diffe- rence in the proportion of muriatic acid for dis- solving the tin ; a difference, however, which did not render the solution in any respect more efficacious. If the murio-sulphuric solution of tin, herein before described, be diluted with about five times its weight of water, and silk be soaked in it for the space of two hours, then taken out, moderately squeezed or pressed, afterwards partly dried, and then dyed, as usual, in a bath prepared with cochineal and quercitron bark, in the proportion of four parts of the former to three of the latter, it will receive a colour ap- proaching very nearly to a scarlet; and this may be made to receive more body by a farther slight immersion into the diluted murio-sulphate of tin, and a second dveinsr in the bath with cochineal and quercitron bark ; and if afterwards a little of the red colouring matter of safflower be superadded by the usual mode of applying it, a good scarlet may be produced. By omit- ting the quercitron bark, and dyeing the silk (prepared as before mentioned) with cochineal only, a very lively rose colour will be produced; and this may be yellowed so as nearly to ap- >34 PHILOSOPHY OF preach the scarlet, by adding a large propor- tion of tartar to the cochineal in the dyeing- vessel. ^Vith lime water as a mordant, cochineal gave to silk a very agreeable purple; with muriate of barytes, a lively delicate lilac colour; with mu~ rio-sulphate of bismuth, a salmon colour ; and with nitrate of cobalt, a very lively and beautiful purple ; with nearly all the other metallic and earthy bases cochineal produced similar, but paler, colours on silk than on wool. The scarlet dye is still less applicable to cotton than to silk, there being, unfortunately, but a slight affinity between the former and the oxide of tin, even when united with the colour- ing matter of cochineal. This was demon - strated by the late M. Dufay, who caused a piece of cloth to be manufactured from a mix- ture of wool and of cotton, which having un- dergone the usual process for dyeing scarlet, be- came, as he describes it, " marbr^e de couleur de feu et de blanc," (marbled with white and fire colours,) the cotton remaining perfectly White, though the wool was dyed scarlet : and he found a like want of attraction between cotton and the colouring matters of kermes and stick lac. He moreover found that a skein of white woollen yarn, and another of cotton, being at the same time, and in an equal degree, submitted to the action of the same preparation, PERMANENT COLOURS. 535 and dyeing liquors, which are commonly employ- ed for scarlet, the woollen yarn received a beau- tiful scarlet, or, as he terms it, "jire colour" whilst the cotton remained as white as at first.* f Similar effects have frequently occurred to me, and I have clearly perceived them to arise, not because the cotton is not capable of imbibing the scarlet dye ; but because, having a weaker attraction for it than that which wool exerts on the particles of that dye, the latter draws, and exclusively appropriates to itself, all the colour contained in the dyeing liquor ; though when cotton is subjected to the same process by itself, freed from the interference of a superior attrac- tion from wool, it takes a scarlet colour, as I know by repeated trials, more slowly, indeed, and paler, than that which is usually imbibed by woollen cloth. It is, perhaps, owing to this weaker attraction between the fibres of cotton, * See Mem. de l'Acad. Ro. des Sciences, kc. 1J37- t In the dyeing of scarlet, it is every day seen, that pieces of woollen cloth or stuff", having at each edge a narrow longitudinal stripe, formed by an intermixture of cotton yarn, after being impregnated in the usual way with the mordant or oxide of tin, will attract and imbibe the colouring particles of cochineal, so as to exhaust the dyeing liquor, and sometimes leave it perfectly colourless, and become scarlet in every part, excepting the stripes formed of cotton-yarn, which always come out of the dyeing liquor without the smallest tinge or change of colour, though both the mordant and the particles of cochineal are applied to the latter equally with tfje-other parts of the cloth. 536 PHILOSOPHY OF and the scarlet dye, that the latter is so much less permanent on cotton than on wool; and it is also from this want of sufficient attraction, that the cochineal colour is found to take most beneficially on cotton, when the basis has been first applied separately. Scheffer, in 1751, recommended the dyeing of scarlet on cotton in tins way, by first soaking it in a diluted nitro-muriate of tin, and after- wards dyeing it with cochineal; but the colour being fugitive, little or no use was ever made of the process; though the late Dr. Berkenhout probably availed himself of it some years after- wards, when he pretended to have discovered the means of dyeing " scarlet, crimson, and other colours, upon cotton and- linen ;" and though his process was not materially different from that of Scheffer, nor in any respect prefer- able to it, he found means to obtain 50001. sterling from the British government, as a reward for making it public* But as no use ever has * Dr. Berkenhout's process having, I believe, never been published, I shall subjoin the account of it, which was " com- municated by order of the Lords of the Treasury to the Company of Dyers in the City of London, the 26th of August, 1779 j" viz. " Cotton or linen, either in yarn or the piece, should be per- fectly wet with hot water, and then wrung out, as is the common practice. " This being done, it must be perfectly soaked in a solu- tion of tin, diluted with an equal quantity of clear soft water. PERMANENT COLOURS. 537 been, or is likely to be made of this supposed discovery, I must hope, and, indeed, 1 think it " The cotton or linen being so far prepared, must be wrung out, but not forcibly j then it is to be nearly dried, laying horizontally upon a hurdle, with a double linen sheet between and covered with the same. " The solution of tin being for scarlet, must be made of ni- trous acid, and not of aqua-fortis ; but for crimson, aqua-fortis must be used } and the bloom is to be given, after it comes out of the dye, by a small quantity of sal-ammoniac and pearl ashes, dissolved perfectly in warm water ; but this water must not be more than milk- warm. " The colouring vat, for the scarlet or crimson, is simply cochineal in water, no hotter than the hand will bear j and as vegetable matter receives only the small particles of the colour from the nature of its pores, two ounces to a pound of the ma- terials dyed may be necessary j but cotton or linen, fresh pre- pared, will draw from the same vat, heated as before, all the inferior shades from scarlet and crimson ; and if any colour still remains in the vat, it may be taken out entirely by wool pre- pared in the usual manner. " The same preparation of tin serves for the green and yellows, with the same materials only that are employed by dyers, except the best yellow, which is produced from tur- meric .* " It is necessary to observe, that after the preparation has been made use of for scarlet or crimson, the residue conti- nues sufficiently strong for greens or yellows, even after it has been kept a considerable time. " N. B. To make the best solution of tin with nitrous acid, it is necessary to have the strong smoking spirit, to which * Nothing can be more erroneous than this and several of Dr Berken- hout's other observations. I VHHHI 538 PHILOSOPHY OF* probable, tbat the Doctor had some better claim to a national remuneration, though, from par- ticular considerations, it was not brought into public view. Besides the fugitive nature of the scarlet dyed by Dr. Berkenhout's process, which, indeed, is calculated to produce only a crimson, and not a scarlet, unless some yellow colour be superadded by other means (which he does not mention,) it is liable to injure the texture of the cotton or linen dyed with it, because the nitric calx of tin, applied as the basis, constantly absorbs oxygene from the atmosphere, and becomes corrosive, whereas, in the present case, this effect can- not be counteracted by occasional washings with soap. Mr. Henry says, that " if a scarlet could be dyed without the use of nitrous acid, the tin. basis might be employed for this purpose on cotton ; but that acid being requisite for the production of this beautiful colour, and being an equal quantity of the purest river water must be added, anl the proportions of the following ingredients, are to the weight cf spirit.one-sixteenth of sal-ammoniac and one-thirty second of re- fined nitre dissolved by little at a time; in this aqua-regia dissolve one eighth of granulated tin, also by small quantities, to prevent too great an ebullition, which would weaken the solution cosiden- bly.The ingredients and proportions are the same, when a sok- tion is to be made with aqua-fortis; but that spirit, in general, will not bear any water when a perfect solution is intended." PERMANENT COLOURS. 539 highly corrosive to colours, this basis is pre- vented from being applied to that substance.'' — Here this ingenious chemist appears to have fallen into the universal error of believing, that nothing but a solution of tin by nitric, or ni- trous acid, can dye a scarlet colour with co- chineal. • lt\ notwithstanding the want of sufficient per- manency in the scarlet colour dyed with cochi- neal upon cotton, it should be deemed proper to apply it to that substance, the best way or' do- ing this which I have yet found, is, to soak the cotton (previously moistened) for about half an hour in a diluted murio-sulphuric solution of tin, as proposed for silk ; then wring or pivss out the superfluous part of the solution of tin, and plunge the cotton into water, in which as much, or nearly as much, clean potash or soda has been dissolved as will neutralize the .acid still adhering to the cotton, so as thereby to decom- pose the oxide of tin, and cause it. to be more copiously deposed or fixed in or upon the fibres of the cotton, which, being afterwards rinced in clean water, may be dyed with cochineal and quercitron bark, in the proportions of about four pounds of the former to two and a half or three pounds of the latter. A full bright colour may be given to cotton in this way, which will bear a few slight washings with soap, aud a considerable degree of exposure to air. Indeed. BBS 540 PHILOSOPHY OF the yellow part of the colour obtained from quercitron bark will even bear long boiling with soap, as well as the application of strong acids, without injury. Cotton impregnated or printed with the aluminous mordant, as commonly applied by calico-printers for madder reds, will,* if dyed with cochineal, receive a very beautiful crim- son colour, capable of bearing several wash- ings, and of resisting the weather for some time, though not long enough to deserve the appella- tion of a fast colour. I think, however, that it is advantageous for calico-printers, in dying madder reds upon the liner cottons or muslins, to add also a little cochineal, the crimson colour of which is admirably calculated to overcome the yellowish hue that degrades the mad- der reds, and arises from a portion of that par- ticular colouring matter which produces the Jauve, or fawn colour, herein before mentioned. By this addition, the madder reds are ren- dered much more beautiful, so long as any part of the cochineal crimson remains, and after- wards they arc no worse than if it had neve: been applied. Cotton printed with iron liquor takes a very full black when dyed with cochineal; but I found this less durable than the same colour dyed from much cheaper matters. A great variety of other colours may be dyed upon cotton impregnated PERMANENT COLOURS. 541 with different metallic or earthy bases ; but as better colours may be more cheaply given by other 'means, I shall offer no farther explana- tions respecting them. A strong decoction of cochineal, thickened with gum, and mixed with a suitable proportion of nitra^ of alumine, being penciled upon cot- ton as a pro-substantive colour, afforded a very full beautiful colour between the scarlet and crimson, which stood some washings, and a considerable degree of exposure to weather. Several of the different solutions of tin being employed, instead of the nitrate of alumine, as well as conjointly with ir, produced xery beauti- ful rose colours, approaching more or less to the scarlet ; and by adding a small proportion of the quercitron bark, they w r ere made scarlet. They could not, indeed, be considered as fast colours, but had the advantage of being very beautiful, and less fugitive than many of those which are too frequently employed by calico printers, under the denomination of chemical colours. Since the preparation or manufacture of Morocco leather has been established in this country, cochineal is employed to communicate the beautiful colour of that, which is called red Morocco ; though in Persia, Armenia. Barbary, and the Greek Islands, a similiar colour was originally produced by the use of either kermes or lac. As a basis for the colouring matter of j42 PHILOSOPHY OF, &c. cochineal, goat-skins deprived of their hair by lime water, and properly cleansed, arc im- pregnated, on that which was the hairy side, with a saturated solution of alum, applied re- peatedly and equally by a spunge, and after an interval of three or four days, a decoction of cochineal, which has been strained, is applied also by a spunge, to the same side or surface, a little, but, not much, more than blood-warm, least it should crisp the leather. This applica- tion is repeated from time to time, until a colour sufficiently full and equal has been produced, Afterwards the skins are soaked in bran liquor, and then tanned by a decoction of either galls or sumach, or of both mixed together. I have found that by substituting a diluted murio-sulphate of tin, for the solution of alum, or by employing a mixture of both upon goat- skins in a suitable state of preparation, the colour subsequent ly produced was considerably improved, at least in vivacity. Having nothing more of importance to com- municate respecting cochineal, I shall here finish this chapter, and in doing so, make an END OF VOLUME THE FIRST. G. SIDNEY, Printer, Northumberland Street, Strand. CONTENTS OF VOL. II. Page. PART II.— CONTINUED. Ghap. V. — Of the coccus ficus, or coccus lacca, and its nidus or comb, commonly called lac, lacca, or lacsha. . i Chap. VI. — Of Prussian blue and its application for dyeing , : 60 PART III. Of Vegetable Adjective Colours. Chap. I. — Of the reseda luteola, Lin. or weld plant, and some other vegetable yellows 95 Chap. II. — Of the properties and uses of the quercitron bark 112 Chap. III. — Of madder, rubia tinctorum, rubia peregrina, and rubia manjit'h 221 Chap. IV. — Of vegetables affording red colouring matters, nearly similar to madder 282/ Chap. V. — Of Brasil and other woods, affording red co- louring matters 3l6 Chap. VI.— Of logwood 338 Chap. VII. — Of vegetables affording adjective brown and other mixed colouring matters, including the fawn or fauve colour of the French 353 PART IV. Of compound colours 37§ Chap. I. — Of orange, green, purple, and violet colours, and their various intermediate shades or mixtures 373 Chap. II. — Of the black dye, and of the common writing ink, as connected therewith, . .'. 337 'mmmi^m ##&» wmm- mi ^#p#»&p? EXPERIMENTAL RESEARCHES CONCERNING THE PHILOSOPHY OF PERMANENT COLOURS. PART II, continued. CHAPTER V. Of the Coccus Ficus, or Coccus Lacca, and its Nidus, or Comb, commonly called Lac, Lacca, or L/tcsha* " La chimie dcs arts ne se borne point a porter eon flambeau " sur oe qui est connu, en a pertectionner ce qui se pratique J ** elle cr£e, chaque jour de nouveaux arts." Ciiaptal. Chimie appliquee aux aris. Discours pr£liminaire. This substance was probably unknown in Eu- rope until after the Portuguese had visited India by sailing round the Cape of Good Hope, and very discordant opinions were entertained of it, for a considerable time after its first im- portation. Cardanus (de subtilitate rerum, lib. viii.) represented lac as a natural gum, exuding * Sir William Jones says, " the Hindus have six names for " Laej but they generally call it Licsbl, from the multitude " of small insects, who, as they believe, discharge ft from theit " stomachs, and at length destroy the tree on which they form " their colonies." Dissertations, &c. relating to the History and Antiquities, &c. of Asia, vol. ii. VOL. II. 5 VHHMHBB vbnhnhniwbrhhhhi ■■■■■■■ 2 PHILOSOPHY OF from a sort of cherry-tree in India. — But tins was contradicted by Amatus Lusitanus, in the first book of his annotations upon Dioscorides, where he asserts, that it is the excrement of a species of winged ants in the kingdom of Pegu; which opinion was also delivered by Christo- pher Acosta, in his treatise de Hist, plant, aro- matumque Indiarum Orientalium. Caneparius, after noticing these opinions, (and others proposed by Garzia ab Horto, Clusius, &c.) endeavoured to convince his readers, that lac was produced by the sap, or juice, of certain trees, wounded by a species of ants, which, by exposure to the air, acquired the hardness of a gum, and retained some of the ants, which, as he supposed, had been caught and entangled therein by its viscidity. He adds, that be- ing boiled, it was employed to give cloths a red colour by dying, and that the colouring matter left in the dying vessel, being afterwards formed into a mass by evaporation, was called an arti- ficial iac, and employed by painters.* He adds, that similar pigments, being afterwards pre- pared from the colouring matters of kermes, Polish cochineal, (or coccus Polonicus) Brazil * " Iecirco coquitur pro tingendis pannis colore rubeoj mo:: ex ipsius reliquiis post tincturam panni conficitur massa quae dicitur Lacca artificialis qua utuntur pictores." De Atramentis, k€. p. 2X4. PERMANENT COLOURS. wood, &c. remaining in the liquors in which cloth and silk had been cfyed with these mat- ters, such pigments were called by the Italians lacca, adding, to this name that of the sub- stance whence the colour was obtained, as " lacca di verzino (Brazil wood) lacca digram, lacca di cremise," &c. and this explanation enables us to ascertain the origin of the English word lake. A much more correct account pf lac, and of the insects producing it, was given by Mr. James Kerr, of Patna, in a communication to the Royal Society, which was published in the Philosophical Transactions for 178 J. By this account it appears, that when the lac insect is first brought forth in November and December, " the head and trunk form one uniform oval ic compressed red body, of the shape and mag- " nitude of a very small louse, consisting of u twelve transverse rings; the back is carinate, ** the belly flat, the antennas half the length of " the body, fili-form, truncated, and diverging, " sending off two, sometimes three, delicate " diversnno- hairs longer than the antennas." The tail is " a little white point, sending off " two horizontal hairs, as long as the body." The insect had three pair of limbs half of its own length; but no wings were seen by Mr. Kerr. As soon as they are brought forth, the insects begin to " traverse the branches of the jb 2 4 PHILOSOPHY OF " trees upon which they were produced for " some time, and then fix themselves upon the " succulent extremities of the young branches. " By the middle of January they are all fixed " in their proper situations, and appear as plump " as before, but shew no other marks of life. " The limbs, antennas, and seta? of the tail, are " no longer to be seen. Around their edges " they are environed with a spissated subpel- " lucid liquid, which seems to glue them to the " branch. It is the gradual accumulation of " this liquid which forms a complete cell for " each insect, and is what is called gum lacca. " About the middle of March the cells are " completely formed, and the insect is in ap- " pearance an oval smooth red bag, without " life, about the size of a small cuchanical *' insect, emarginated at the obtuse end, full of " a beautiful red liquid. In October and No- " vembcr we find about twenty or thirty oval " eggs, or rather young grubs, within the red " fluid of the mother. When this fluid is all 11 expended, the young insects pierce a hole " through the back of their mother, and walk " off one by one, leaving their exuvia? behind." According to Mr. Kerr, the lacca insects in the country where he wrote, were found in four species of shrubs: First, Ficus Religiosa, Lin. Second, Ficus Indica, Lin. Third, Plaso Hortus Malftbaraci ; and, Fourth,,. Rhamnus Jujuba, PERMANENT COLOURS. Lin. — They fix themselves in such multitudes on these trees, and more especially of the three first, that " the extreme branches ap- " pear as if they were covered by a red dust; " and their sap is so much exhausted, that " they wither and produce no fruit." Birds perchmg on these branches carry off' gicat numbers of the lacca insects, adhering to their feet, and' transplant, by depositing them, on other trees where they rest. " The gum lacca of this country (says Mr. " Kerr) is principally found upon the unculti- " vated mountains on both sides of the Ganges, " where bountiful nature has produced it in " such abundance, that were the consumption 11 ten times greater than it is, the markets " might be supplied by this minute insect. " The only trouble in procuring the lac is in " breaking down the branches, and carrying " them to market. The present price in Dacca " is about 12s. the 1001b. weight, although it is " brought from the distant country of Assam. " The best lac is of a deep red colour. If it be " pale, and pierced at the top, the value di- 11 minishes, because the insects have left their " cells, and consequently they can be of no use " as a dye or colour :" though the lac itself may be better for varnishes. The lacca is capable of being applied to se- veral uses. That of dying, however, is alone 6 PHILOSOPHY OF the object of our present inquiry; and for this it is supposed to have been known and employed by the ancients; btlt this cannot be ascertained, because they have left no description of it suffici- ently accurate. (See Salinas. Lxcrcit p. 8'0.) By Mr. Kerr's account, the native Indian in- habitants, after extracting the colouring matter of the lac by hot water, mix alum and tamarind water with the decoction, and dye silk and cot- ton therein. A further account of the lac insect was, a few years afterwards, communicated to the Royal Society, by Mr. Robert Saunders, and published in the Philosophical Transactions for 1789, of which the following are extracts, viz. " Lac is known in Europe by the different appellations of stick lac, seed lac, and shell lac. The first is the lac in pretty considerable lumps, with much of the woody parts of the branches on which it is formed adhering to it.* Seed Jac is only the stick lac broke into small pieces, * Stick lac is properly the lac in its natural state, adhering to, and often completely surrounding, for five or six inches, the twigs on which it is produced by the insects contained in its cells. When the twigs or sticks are large, and only partially covered, the lac is frequently separated from the sticks, as, indeed, it ought always to be when shipped for Europe, to avoid paying freight uselessly for the latter. Sometimes pieces of lac, with or w.ihout the twigs, after having been exposed to great heat from the Sun, cohere and form lumps. PERMANENT COLOURS. 7 garbled and appearing in a granulated form.* Shell lac is the purified lac by a very simple process, to be mentioned afterwards. ~\ " The tree on which this fly most commonly generates is known in Bengal by the name of the biher tree, and is a species of the rham- * This account of seed lac is very incorrect. When lac has been separated from the twigs to which it naturally adheres, and coarsely pounded, the silk and cotton dyers extract the colour, as far as it can conveniently be done, by water ; after which the yellowish hard resinous powder, in appearance some- what resembling mustard seed, is called seed lac. 1 have corn- pared samples of seed lac as imported and deposited in the warehouses of the India Company, with powdered stick lac, treated in the way just described, for my own experiments, and have found loth to be exactly similar in appearance and in the fact of their containing but a small, and nearly an equal rem- nant of colouring matter. f Shell lac is produced from seed lac, by putting the latter into long cylindrical bags of cotton cloth, and melting it, by holding the bags over a charcoal fire, and when the lac melts, straining, or forcing it through the pores of the cloth, by twisting the bags ; which is done by two men, one holding each end of a bag. The lac so strained, is made to fall upon the smooth junk of a plantane tree, (Musa Paradisiaca) and is there spread into thin plates, or lamellae. — The resin being the most liquifiable part of the lac, it thus passes, almost exclu- sively, through the strainer, and in a considerable degree of purity. Shell lac is principally employed in Europe to compose varnishes and sealing-wax. The latter use of it, was noticed by Garzia ab Horto, in 1562. (See Aromaturn et simpliciurn aliquot Historia, &c.) 8 PHILOSOPHY OF nus.* The fly is nourished by the tree, and there deposits its eggs, which nature has pro- vided it with the means of defending from ex- ternal injury by a collection cf this lac, evi- dently serving the two-told purpose of a nidus and covering to the ovum and insect in its first stage, and food for the maggot in its more ad- vanced state. The lac is formed into complete cells, finished with as much regularity and art as a honey-comb, but differently arranged. The flies are invited to deposit their eggs on the branches of the tree, by besmearing them with some of the fresh lac, steeped in water, which attracts the fly, and gives a better and larger crop. " The lac is collected twice a year, in the months of February and August. " I have examined the egg of the fly with a very good microscope ; it is of a very pure red, perfectly transparent, except in the centre, where there were evident marks of the embryo forming, and opaque ramifications passing off from the body of it. The egg is perfectly oval, and about the size of an ant's egg. The mag- got is about one eighth of an inch long, formed of many rings, (ten or twelve) with a small red * This is a mistake j the biher, or bihar tree, is the croton laccifeium, Lin. which seems to be generally preferred by the lac insects. It is described by Louxeiro, Cochinchina, i. p. 582. PERMANENT COLOURS. 9 head; when seen with a microscope, the parts of the head were easily distinguished, with six small specks on the breast, somewhat project- ing, which seemed to be the incipient formation of the feet. This maggot is now in my cus- tody, in the form of a nymph, or chrysalis, ils annual coat forming a strong covering, from which it should issue forth a fly. " Nature has provided most insects with the means of secreting a substance which generally answers the two-fold purpose of defending the embryo and supplying nourishment, to the insect, from the time of its animation till able to wander abroad in quest of food. The fresh lac contains within its cells a liquid, sweetish to the taste, and of a fine red colour, miscible in water. The natives of Assam use it as a dye, and cotton dipped in this liquid makes afterwards a very good red ink. " Assam furnishes us with the greatest quan- tity of lac in use ; and it may not be generally known, that the tree on which they produce the best and largest quantity of lac, is not un- common in Bengal, and might be employed in propagating the fly, and cultivating the lac, to great advantage. The small quantity of lac collected in these provinces, affords a precarious and uncertain crop, because not attended to. Some attention at particular seasons, is neces- sary to invite the fly to the tree; and collect- 10 PHILOSOPHY OF iug the whole of the lac with too great an avidity', where the insect is not very generally to be met with, may annihilate the breed." Of the four species of shrubs upon which, Mr. Kerr says, the lacca insects are found in the countries adjacent to Patna, there is only one, the rhamnus jujuba, upon which Dr. James Anderson could find them near Madras, though he observed them on several species of mimosa, and on some other trees and shrubs. Dr. Roxburgh, indeed, seems to think, that on the coast of Coromandel they only inhabit shrubs of the mimosa kind, and even but three species of this genus. He says, (see Philos. Trans. 1791,) that " some pieces of fresh look- • s ine lac adhering to small branches of the " mimosa ciuerea, Lin. were brought to him '• on the 20th November, 17S9," and being carefully kept in wide-mouthed crystal bottles, slightly covered, after fourteen days had elapsed " thousands of exceeding minute red animals '■ were observed crawling about the lac and the " branches it adhered to, and still more were " adhering to the surface of the cells. By the " assistance of glasses, small imperforated ex- " crescences were also observed interspersed " among the holes ; two regularly to each " hole, crowned with some very fine white " hairs, which being rubbed off^ two white " spots appeared. The animals, when single, PERMANENT COLOURS. 11 " ran about pretty briskly ; but in general, on " opening the cells, they were so numerous as " to be crowded over one another. " The substance of which the cells were a formed, cannot be better described, (says Dr. " Roxburgh) with respect to appearance, than " by saying, that it is like the transparent " amber that beads are made of, The external " covering of the cells may be about half a 11 line thick, is remarkably strong, and able to " resist injuries; the partitions are much " thinner. The cells are in general irregular " squares, pentagons, and hexagons, about an " eighth of an inch in diameter, and a quarter " of an inch deep ; they have no communica- " tion with each other. All those I opened, " during the time the animals were issuing from " them, contained in one side, which occupied " half the cell, a small bag filled with a thick " red jelly-like liquor, replete with what I take " to be the eo-o-s. These bags, or utriculi, " adhere to the bottom of the cells, and have v each two necks, which pass through perfora- " tions in the external coat of the shells, form* " ijng the beforementioned excrescences, ending " in some fine hairs. " The other half of the cells has a distinct '/opening, and contains a white substance, like u some filaments of cotton rolled together, and 4< a cumber of the little red insects themselves, 12 PHILOSOPHY OF about ready to make their exit. " Their portion of eacli cell is about one half, iC and I think must have contained near one " hundred of these animals. Other cells less " forward, contained in this half, with one " opening, a thick, red, dark, blood-coloured " liquor, with numbers of exceedingly minute " eggs, many times smaller than those found in " the small bags which occupied the other half " of the cells." Dr. Roxburgh describes the circumstances and progress of these insects, and particularly the females, through the larva and pupa on- wards, to their perfect states, which last they did not reach until near five months. The male insect in the perfect state was about the size of a very small fly, and exceedingly active ; with an obtuse head, black eyes, oval brown trunk, six legs for running and jumping, and four mem- branaceous incumbent wings, of which the an- terior pair was twice as long as the posterior, but he had no tail. The female insect, in her perfect sfate, was rather smaller than the male, and of a brighter red colour, though less active. Her head and eyes were very small ; trunk red, and almost or- bicular ; abdomen red, oblong, and composed of twelve annular segments ; she had six legs for running and jumping, with only two long transparent incumbent wings, and a tail con- sisting of two white hairs as long as her body. PERMANENT COLOURS. 13 " The eggs, and dark-coloured glutinous li- "quor they are found in, (continues Dr. Rox- " burgh) communicate to water a most beau- S PHILOSOPHY OF elementary constituent of this colourable Prus- siajte, will nor, at the same time, receive any, even the slightest accession of oxygene, but will continue unchanged, in the condition of a black oxide, united to the oxygene, only in the proportion of twenty-eight per cent. That iron, at the minimum of oxidation, is incapable, whatever may be the proportion, of becoming, or producing, a blue with the colour- able Prussiate, may be demonstrated by several experiments, described by Proust. But the easiest and most simple is that of dropping some of the crystallized Prussiate into a recent diluted boiling solution of the green sulphate of iron, where it will cause a white precipitation, which Proust calls the white Prussiate of iron, and which is of that colour, only because the exide is at the minimum of oxidation ; but as this (unlike the elementary portion of black oxide) retains a disposition to become hyper- oxidated, it will constantly absorb oxygene, and gradually pass from the white to the blue colour; an effect which is analogous to some that we have found to happen with indigo, and which oceur also to an infusion of galls, when mixed with the green sulphate of iron. I have obtained a similar white precipitation, in the same way, by substituting the Prussiate of lime for the crystallized Prussiate of potash ; and also by substituting the muriate of iron, recently prepared, for the green sulphate ; the iron in PERMANENT COLOURS. GO both being equally at the minimum of oxida- tion. I have also gummed this white precipi- tate, and applied it in spots to muslin and cot- ton velvet, and found it (by absorbing oxygene) to change speedily to a full and most beautiful blue ; and this has happened to calico which I had soaked in Prussiate of potash and dried, upon my applying to it, in spots, a diluted mu- riate of iron thickened with gum — no colour was visible at first, but the spots soon became blue, by absorbing oxygene. But when, to a piece of calico impregnated with Prussiate of iron, in the same way, I applied a diluted nitrate of iron, (also in spots) the production of blue was instantaneous, because the iron in the nitrate was already at the maximum of oxida- tion. I found afterwards, upon soaking the same calico in bydro-sulphuretted water, that the blue spots, by ^'oxygenation, were again made white, and afterwards rendered blue a second time, by immersing the calico in a di- luted nitric acid, which restored the oxygene."* * M. Berthollet has supposed that the white prussiate of iron differs from the Hue, not because it is less oxygenated, but be- cause the sulphuric acid in the green sulphate of iron adheres most strongly to its basis, and as a proof of this, he says, that by adding either the muriatic, sulphureous, or phosphoreows acids, to the white prussiate, it becomes blue, though neither enn bo supposed to atford oxygene. But it must have been almost im- possible to make such an addition, without admitting oxygene from the atmosphere. 70 PHILOSOPHY OF Bouillon Lagrange says, (Manuel de Chimie, ii. 653) that the Prussic acid will decompose the oxymuriatic, by absorbing the oxygene of the latter, and that it will become odourous ; and that, in this state, it will precipitate iron of a green colour, which green, by the contact of' the sun's rays, or by an addition of metallic iron, or of sulphureous acid, will be changed to blue ; and as these are all deoxygenating agents, we must conclude, if the fact be correctly stated, that the green colour, in this case, results from an excess of oxygene, and that it is changed to blue by an abstraction of that- excess. The uncommon beauty and lustre of the Prussian Blue, have occasioned many endeavours to apply and fix it equally and permanently as a dye. The 'late Mr. Macquer first proposed two methods of doing this ; but neither proved successful. In one he soaked the stuffs in a solution of alum and sulphate of iron, and then in a diluted Prussiate of potash; and lastly, in water a little soured by sulphuric acid, in order to dissolve and remove any superfluous oxide of iron. By doing this repeatedly, he produced a very beautiful blue colour; but it took une- qually, and the texture of the silken and woollen stuffs was rendered very harsh. In Mr. Macquer's second process the stuffs to be dyed were boiled in a solution of alum and tartar, and afterwards in water, containing PERMANENT COLOURS. 71 Prussian blue, which had been finely powdered. In this, however, the colouring particles were only suspended, without being dissolved, and therefore, though they were applied to the fibres of the stuffs, it was without any chemical union, and so sparingly as only to produce very faint shades of colour. The Abbe - Menon recommended a different process for dyeing linens and -cottons with the Prussian blue. They were first dyed black in the usual way, with a ferruginous basis; and then soaked a few minutes in a diluted Prussiate of potash ; after which they were boiled in water with alum, and took thereby a deep blue." In this case the Prussian colouring matter, as- sisted, doubtless, by the acid of the alum, seemed to exert a strong attraction upon the oxide of iron contained in the black dye, and thereby to decompose and separate the vege- table colouring matter, (of galls, &c.) and in its stead to combine with the ferruginous basis-; but the colour took unequally. Some years since, M. Roland de la Platrierc* published among the " Arts et Metiers'' of the Royal Academy of Sciences at Paris, an account of another method practised at Rouen for dye- ing with the Prussian blue, in many respects * This gentleman, divested of the name of La Platriere, was one of the ministers of the French Republic, in the early- part of the Revolution, and, perhaps, one whose conduct was the least exceptionable. 72 PHILOSOPHY OF similar to Mr. Macquer's second process ; but with this difference, that the Prussian blue in fine powder was suspended, not dissolved, by a diluted muriatic acid, instead of pure water; a change which seems to have been attended with some advantage, though it was with difficulty, and not without many precautions and tedious operations, that an equal colour of sufficient body could be obtained ; and then, though highly beautiful, it was not in a state of che- mical combination with the fibres of the cotton velvets, for which it was principally used, and therefore was liable to be easily abraded by wearing and friction, especially in those places where it had been folded. Air, however, did not weaken the colour in any degree, nor was it injured by acids. A little time before this, M.le Pileur d'Apligny announced to the world, that he had discovered the means of dyeing a blue, as far exceeding all other blues in beauty and lustre, as the cochi- neal scarlet exceeds the common reds. He, however, kept his process secret, until the offer of a premium induced him to make it public. He began it by impregnating the stuffs to be dyed with an iron basis, which he prepared by deflagrating equal parts of old iron and salt- petre in a crucible, afterwards washing the resi- duum, and dissolving it in vinegar and bran- water. This being sufficiently diluted, was ap- plied as a mordant, in the usual way, to the PERMANENT COLOURS. 73 stuffs, which were afterwards well rinced, and dyed in a preparation of Prussian blue, made by dissolving two pounds thereof (in the moist state in which it is first precipitated) by half a pound of potash, in boiling water, and after- wards adding three ounces of common oil of vitriol, or an equivalent portion of nitric acid, so as to neutralize the alkali, without precipi- tating the colour. A sufficient quantity of this put into a dyeing vessel, with hot water, and the stuffs, previously impregnated with the iron mordant, being dyed therein, they became at first green, and afterwards of a beautiful blue colour; which was, however, still liable to take unequally, and, therefore, M. d'Apligny's pro- cess, as far as I can learn, has never been carried into any considerable use. In the thirteenth volume of the "Annales de Chymie," M. Berthollet gives an account of certain ideas which had occurred to him, re- specting the defects of all the means used for dyeing with Prussian blue, and of some expe- riments made at his desire by Mr. Vidmer, of the celebrated calico printing establishment at Jouy, for correcting these defects. It was found by these experiments, that pieces of cotton, impregnated with the acetate of iron, or iron liquor, notwithstanding all possible endea- vours to apply it equally, took up the colour of Prussian blue (first dissolved by potash, and then mixed with either sulphuric or muriatic 74 PHILOSOPHY OF acid) so very unequally, as to leave no hope of success in this way. M. Berthollct accounts for this inequality of colour, by supposing, that one part or particle of iron is sufficient for six of the Prussian colour; and that, therefore, the slightest difference in the distribution of the particles of that metal in the mordant, becomes very sensi- ble, when the Prussian colouring matter is after- wards superadded thereto. Mr. Vidmer was particularly struck with the greens which were produced with the Prussian blue, upon patterns previously dyed olive in the usual way, by the iron liquor and weld, which greens greatly surpassed in beauty all those given by any other means. M. Berthollet, by experiments which were afterwards made separately from Mr. Vidmer, discovered, that the solution of Prussian blue by lime water, (prussiate of lime) succeeded as well as that by potash, and that it required less care respecting- the proportions : but he thinks, and with great reason, that the alkaline solution will have the advantage of being af- forded cheaper, because when animal matters have been calcined with potash, nothing more will be necessary than to saturate the excess of alkali, by adding to it a little Prussian blue. M. Berthollet's method was to dilute the prussiate of lime with three or four times as much water, or to dilute with a large quantity of water, a small one of the prussiate of potash, PERMANENT COLOURS. 75 and then to mix with it a little sulphuric acid;* and keeping the liquor at the heat of between twenty and thirty degrees of Reaumur's ther- mometer, to immerse the cotton, linen, or^ilk, therein, (having first soaked it in warm water) and turn it over a winch, &c. as usual, in order that the colour might he equally applied. The dye was found to take sufficiently in a few minutes, and then the stuffs were taken out and washed in cold water. He found the sulphuric acid preferable to the muriatic for this purpose. Cotton and silk previously dyed grey or brown with galls, or other nigrescent vegetable colouring matters, applied to a ferruginous basis, acquired, by the process just mentioned, a blue colour, proportioned to the depth of the former brown or grey ; and those which had been pre- viously dyed olive, by the application of weld, or other adjective vegetable yellows, took also a beautiful green, proportionate to such olive colour. He says nothing of the effects of this method of dyeing on wool, having made scarce any trials therewith. * The use of sulphuric acid will be readily understood, by recollecting that alkalies decompose Prussian blue by their greater affinity for its colouring matter than that of the iron, and that this last cannot, therefore, decompose the prussiate of potash, unless its affinity for the iron is assisted by that of an acid for the potash in the way of a double elective attraction. 7G PHILOSOPHY OF Cotton and silk dyed black by the ordinary means, were found, by superadding a blue in M. Berthollet's method, to become more per- fectly black, as well where the original colour had faded, as where it had been but imperfectly produced at first. He cautions against using too much acid, as well as against making the dyeing liquor too hot, and keeping the stuffs too long therein, especially the silk, which would there- by lose some of its lustre and softness. One great defect, however, attending this method of dyeing, especially upon cotton, is, that the stuffs, to which the Prussian blue has been applied, will not bear washing, because, though the colour resists air extremely well, the alkali contained in soap readily dissolves and separates the Prussian colouring matter. As a remedy for this defect, M. Berthollet recom- mends washing the cottons, dyed by this pro- cess, with bran and water, instead of soap, which, he says, will likewise have the advantage of preserving the other colours of printed cot- tons, or rather of not injuring them, as washing with soap generally does in some degree. Among the effects mentioned by M. Berthollet, that which I thought the most surprising was, the change of what he (improperly) calls. an olive colour, produced by weld and iron liquor, to a very beautiful green, by the application of Prussian blue in the way before described. The green. PERMANENT COLOURS. 77 in this instance, manifestly could not be pro- duced without a mixture of yellow with the blue ; and weld, the only colouring substance from which it could, in this case, be obtained, never would afford any such colour without the aluminous, or some other basis, very diffe- rent from iron. I determined, therefore, as soon as possible, to ascertain the truth respecting this point ; and to do it, I took a large piece of cotton, which had been printed in parallel longitudinal stripes, (extending from end to end) first with a mixture of iron liquor and galls, next, with iron liquor only, then with a mixture of iron liquor and the aluminous mordant, (acetite of alumine,) and lastly, with the aluminous mor- dant only ; then followed a white stripe, to which nothing had been applied, and these stripes were alternately repeated, so as to cover the piece. This I dyed in the usual way, with a decoction of quercitron bark, by which the first stripe became black, the second of a dark drab colour, the third of an olive, and the fourth yellow. I then took a solution of potash, fully saturated with the Prussian colouring matter, and poured some of it into a large vessel nearly filled with moderately warm water, and added to it a large proportion of oil of vitriol, (sul- phuric acidj which, from its weight, sunk to the bottom. I took care, however, by stirring, to mix it thoroughly with the liquor, which be- PHILOSOPHY OF came uniformly blue, and had a sour taste. I then tore oft' a transverse strip of the dyed cot- ton, of the whole breadth of the piece, and im- mersed it, for a single minute only, in the liquor; when, on taking it out, I found that every particle of the colouring matter of the galls and quercitron bark had been discharged, and replaced by the Prussian colouring matter, upon the stripes where an iron basis had been at first applied ; nearly according to the quan- tum of that basis. The first stripe, therefore, instead of being black, w r as of a very full, deep, strong, blue colour; the second was sufficiently full, though very sensibly weaker; and the third was still weaker ; the fourth, to which the aluminous basis only had been applied, was of a very pale bluish colour, almost as slight as the fifth, which had not been impregnated with any basis or mordant. To diminish the excess of sulphuric acid in the liquor, as well as to replenish it with colouring matter, I added thereto a farther portion of prussiate of potash, which being properly mixed, I immersed ano- ther strip, torn from the same piece of cotton, and taking it out also, after a single minute, I found that, in this instance, the excess of sul- phuric acid had not been so great as to dis- charge the colouring matter of the galls, though it had totally discharged thtt of the quercitron bark. I had, therefore, instead of a very PERMANENT COLOURS. 73 dark blue on the first stripe, a very full black, greatly superior to the former black from galls and iron, it having become much more intense by an additional body of blue colour. All the other stripes were very similar to those of the preceding trial. I then perfectly neutralized the excess of acid in the dyeing liquor, b} T adding to it a sufficient quantity of prussiate of potash; and a third strip of the same cotton being put into it for the same space of time, I found that none of the colour- ing* matter of the quercitron bark was dis- charged in those parts or stripes where it had been united to the aluminous basis, though it had been every where decomposed and separated from tiie ferruginous, and its place supplied by the co- louring matter of the Prussian blue. I had, therefore, on the second stripe, a blue colour, instead of the drab which the quercitron bark had produced with the iron liquor ; and on the third stripe, instead of an olive, I had a very beautiful green, composed partly of the yellow from the quercitron bark and the aluminous basis, and partly of a line blue, which the Prussian colouring matter had produced on the same stripe, by uniting with the ferrugi- nous particles of the iron liquor, which had been previously mixed with the acetite of alu mine, and applied as a mordant upon that stripe. The yellow upon the fourth stripe re- so PHILOSOPHY OF mained in full perfection ; and the fifth stripe was perfectly white, having been quite freed from a slight discolouration which the quer- citron bark had produced on it in the dyeing vessel. By this, and many similar experiments, made some of them with weld, instead of quercitron bark, 1 clearly perceived that M. Berthollet must have been mistaken, when he supposed that the olives, which were changed into beautiful greens in the manner before men- tioned, had been given by the weld and iron liquor only, because no such effect can be pro- duced, either from that or any other adjective vegetable colouring matter, without the aid of alumine, or of oxide of tin, to produce a yellow, whilst the ferruginous basis, by attracting the Prussian colour, produces a blue, the other component part of the green.* I ascertained this fact more completely, by extending my experiments to woollen cloth, of which M. Berthollet says nothing in this respect. I be- * M. Berthollet has since acknowledged his mistake, with becoming candour and promptitude ; he says, (torn. ii. p. 319 of the last edition of his Elements, &c.) " Dans cette opera- tion le fer se combine avec l'acide Prussic et forme du lieu, pendant que l'alumine fait du jaune avec la substance color- ante ; et Bancroft a raison, de combattre l'explication qu'on aurait donne de cette production de vert, dans laquelle on ne fesait point entrer le concours de l'alumine." And he then refers to his Memoir, Ann. de Chimie, torn. xiii. PERMANENT COLOURS. SI gan by dyeing pieces of white broad cloth, some with weld and sulphate of iron, others with quercitron bark and the same sulphate, which, in both cases, produced nearly similar drab colours; and the pieces being so dyed, I immersed them in different portions of diluted prussiate of potash, neutralized with sulphuric acid, a little more than blood-warm, in which they all, after ten or fifteen minutes, became blue; the Prussian colouring: matter having decomposed and separated that of the weld and quercitron bark, which, by suitable expe- riments, I afterwards found to be contained in the several liquors, where the Prussian colouring matter had before been suspended.* If, in- stead of dyeing the cloth with weld or quer- citron bark, and sulphate of iron only, I used alum along with the latter, an olive was pro- duced ; and this, being soaked, as before men- tioned, in warm diluted prussiate of potash, (neutralized with sulphuric acid) it produced a beautiful green; the alum and quercitron bark, * This fact affords a remarkable instance and illustration of the elective attractions, subsisting between adjective colouring matters and the metallic oxides, alumina, &c. as we see that, in consequence of these attractions, the colourable prussiate was able to separate ihe coloring matters ot weld and quercitron bark, when previously combined with their bases, and fix itself in their stead. VOL. IF. G 81 PHILOSOPHY OF or weld, furnishing a sufficient quantity of yellow, for that purpose, and the Prussian blue, by its superior brightness, giving the green an increased lustre. In all these, and many other experiments, I found that though the Prussian colour in this way readily decomposed, and se- parated most of the adjective colours, united to a ferruginous basis, (for which it has a stronger attraction) it had not any attraction for the aluminous basis sufficiently strong to separate the colouring matters combined therewith : and hence, in all cases where a portion of alu- mine had been united with iron, to form the basis or mordant, and an olive colour had been thus produced by weld, or quercitron bark, either upon cottons, silk, or wool, a green inva- riably resulted, from an application of the Prussian alkali with sulphuric acid, unless where this acid was made to predominate so greatly as to decompose, even that part of the vegetable colouring matter which adhered to the aluminous part of the basis. By reflecting upon these facts, I was led to a method of applying the Prussian blue for dyeing upon woollen, silk, and cotton, which seems to me capable of obviating the difficulty hitherto attending its use for these purposes. I have already mentioned M. Berthollet's opinion, that the inequality of colour to which the dyeing with Prussian blue is liable, arises from PERMANENT COLOURS. 83 the difficulty of applying the ferruginous par- ticles alone equally to all the fibres of the cloth; though this may be easily clone, when the par- ticles of the iron are combined with those of different adjective vegetable colours; I there- fore boiled up what I conceived to be suitable proportions of sulphate of iron with quercitron bark, fustic, and logwood, separately, and then dyed a piece of woollen cloth in each of these mixtures, by boiling it therein for ten or fifteen minutes; I chose these vegetable dyeing drugs, without any regard to their particular colours, because they are the cheapest, and because they do not contain any mixture of that particular substantive colouring matter found in galls, sumach, &c. which the Prussian colour would be less capable of decomposing and discharging. The pieces so dyed appeared to have imbibed the vegetable colouring matters equally, and as far as I could judge, the ferruginous basis also; and being afterwards immersed in warm diluted prussiate of potash, neutralized by sulphuric acid, they became beautifully blue; and though there were some little inequalities in the colour of one of the pieces, I ascribed it rather to my own want of attention to the proper stirring and management of the dyeing liquor, and of the cloth, than to any unavoidable difficulty in giving evenness to the dye. I found also, by subsequent experiments, that some nicety was Q 2 84 PHILOSOPHY OF required to proportion the quantity of the oxide of iron (applied conjointly with the vegetable colouring matters) to the depth of blue colour intended to be dyed upon the cloth ; for where an excess of the former was first applied, beyond the portion required to saturate the Prussian colourable matter, that excess gave die blue a greenish tinge. This, however, may be readily discharged, by passing the cloth through warm water, slightly soured by muri- atic acid; though a few experiments would be sufficient to ascertain exactly the quantity of sulphate of iron necessary for producing any particular shade of blue in this way, upon any given quantity of cloth, and thereby obviate all difficulty on this point.* It is necessary always to apply the Prussian colouring matter in a moderate heat, otherwise it will be preci- pitated by the sulphuric acid, and rendered unfit for this purpose, unless dissolved again by pot- ash, lime, &c.f * I found afterwards, that the sulphate of iron would afford a sufficient basis for between sixty and an hundred times its weight of cloth according to the fulness of the blue intended to be dyed. f Encouraged by the apparent success of these experiments, I have several times, since the former edition of this volume, renewed my attempts to render the Prussian blue available for dyeing broad-cloths, believing, from the incomparable leauly of its colour, and the constancy with which it resists all impres- PERMANENT COLOURS. 85 I shall offer something more respecting the use of Prussian blue for dyeing a most beautiful green upon woollen cloth, when I come to treat of the properties of quercitron bark. To ascertain whether any affinity existed be- tween the aluminous basis and the colouring matter of Prussian blue, I took a piece of cot- ton, which had been printed with the aluminous mordant, and cleansed as usual for topical dyeing, and immersed it in warm dieted prus- etons from the sun and air, as well as of acids, that it might become an important acquisition, though unfit to withstand the action of soap; to which, indeed, broad-cloths are but rarely- subjected. But though I have, in many instances, dyed pieces of cloth, of the size of those upon which my experiments are commonly made, (i. e. from six to twelve inches square) with a perfect evenness of colour, and with indescribable vivacity and lustre; I have, also, frequently failed to attain the requisite equality in the colour; and it has seemed to me that the ex- treme brightness of the blue, dyed in this way, has contributed to these failures, by rendering the slightest inequalities strikingly perceptible. I have now before me some of the pieces of cloth so dyed, and though the colour of several of them is intensely full, its lustre greatly surpasses every thing before seen in wool, and emulates even the transparency and brilliancy of the finest saphire, to such a degree that the eye, which his once seen the Prussian blue, so communicated, disdains after- wards to fix itself upon the common indigo blue. The seeming difficulty of giving the former of these colours with sufficient evenness, to a whole piece of cloth, has, indeed, hitheito restrained me from attempting to do it ; but I am not without a strong hope of its being ultimately performed. 86 PHILOSOPHY OF siate of potash ; seeing, however, at the end of fifteen minutes, that it had acquired no colour, I put into the liquor asmall proportion of a solu- tion of iron by muriatic acid, which rendered it blue, and the cotton soon became of that colour pretty equally, without any manifest difference of colour in the places to which the aluminous mordant had been previously applied. Taking the cotton out of this dyeing liquor, I tore off a bit of it, and washed it with soap, which soon discharged all the colour, excepting where the cotton had been impregnated with alumine, and there it was considerably weakened, though enough remained to show that it had been attracted and rendered more fixed by the aluminous basis. Another bit of the same cotton was immersed in a solution of carbonate of ammonia, (mild volatile-alkali) which having a power of decom- posing the Prussian blue, I supposed it would weaken, if not wholly discharge the colour. To my surprize, however, I found that it greatly augmented the blue, which before was rather pale, and gave it almost the appearance of what is called garter blue; an effect which will, per- haps, be the less surprising, if we consider, that volatile alkali, like the Prussian colouring mat- ter, is an animal production, and that, excepting the carbone of the latter, both are composed of the same principles. Another bit of the same cotton being put PERMANENT COLOURS. S7 into water, very slightly tinctured with a solu- tion of copper by volatile alkali, the blue co- lour, in a very sudden and surprizing degree, augmented to an intensely deep garter blue, or violet, much exceeding that produced by the ammonia alone ; -and this being afterwards washed with soap, the colour of those parts where the aluminous mordant had been at first applied, was still better fixed than it had been on the like parts by the volatile alkali alone in the preceding trial. Another piece of the same cotton being im- mersed in water, with which a very little muri- ate of copper had been previously mixed, soon became of a deeper blue, but without any of the purple or violet hue which had been produced in the two preceding instances. This piece being afterwards washed with soap, I perceived that the colour where the aluminous mordant had been applied, was still much more firmly fixed than it had been by any other means. Indeed, after a severe washing, which completely discharged the colour every where else, the spots or parts impregnated with alu- mine retained a full strong blue, which the soap had, indeed, turned a little towards a violet colour; but, after being well rinced in clean water, it returned again to its proper com- plexion, and stood a long exposure to weather unaltered, and afterwards two or three severe S3 PHILOSOPHY OF washings with soap, without much diminution of colour.* It must, however, he remembered, that if copper thus manifestly fixed the Prus- sian blue, it was only in those parts where the aluminous mordant had been at first applied; since the other parts of the cotton were washed white with as much facility as they were on the bit to which nothing had been applied after it became blue ; so that, doubtless, both the alumine and copper together, greatly contribute to fix the colouring matter of Prussian blue. The copper, indeed, as we shall presently see, possesses a power of uniting therewith, and producing one of the most permanent of co- lours, even upon linen and cotton ; a fact which, I believe, never was imagined by any one, until it very lately fell under my observa- tion. From these proofs of the utility of an aluminous basis in fixing the Prussian blue, it would, I think, prove advantageous to prepare woollens by the usual boiling with alum, or alum and tartar, before they are dyed with copperas and quercitron bark, fustic, or log- * In this and the other pieces, the blue upon the spots im- pregnated with alumine, after it had been weakened by wash- ing, was rendered nearly as strong as ever, by dipping them into water, slightly soured with sulphuric acid, so as to decom- pose and neutralize the alkali which had been imbibed from the soap in washing ; perhaps the acid also restored the oxy^ gene which had been separated by the soap. PERMANENT COLOURS. 89 wood, for a Prussian blue. But in this case it would be necessary to mix a greater proportion of sulphuric acid in the prussiate of potash, or of lime, in order that an excess of acid may assist in discharging these vegetable co- louring matters, otherwise, instead of a blue they would produce a green; or a black, where logwood had been employed with the sulphate of iron. Having soaked pieces of silk and of cotton in the diluted prussiates of potash, soda, lime, and ammonia, or volatile alkali, separately, and afterwards dried them, I applied to each, by the pencil, a little of the solutions of all the metals and semi-metals in different acids, and also in alkalies, where they were soluble in the latter, in order to see the effects of all these several bases upon the Prussian colouring matter. I should tire the patience of my readers, were I particularly to describe the lesults of these different combinations, especially as no words could rive adequate ideas of the great variety of shades and degrees of colour, and particu- larly of the blue produced by them, which varied extremely in fulness and brightness, as well as in its inclination towards the pur- ple and violet on one hand, and green on the other; and, indeed, the diversities of blue only, (which was the colour produced by much the greatest number of metallic sclu- 90 PHILOSOPHY OF tions) would alone constitute a very pleasing variety of colour in the way of printing upon silk or cotton. There were, however, several other colours produced at the same time ; e. g. the nitro-muriate of gold produced a very beau- tiful green, inclining a little to the yellow, which, by washing, changed somewhat to the olive, whilst the nitro-muriate of platina pro- duced a green, inclining to the blue. The nitro- muriate of cobalt produced a grass green ; the nitrate of mercury, a greenish yellow; and the nitrate of nickle, an olive brown.* * As I have not abstained from correcting what has ap- peared to me erroneous, even though sanctioned by Newton in Optics, and Berthollet in Chemistry, it is my duty, with still greater promptitude, to detect, avow, and correct, my own errors, as far as I am able : and I therefore declare, that I was deceived when I supposed that the Prussian colourable matter had produced blue colours of different shades, in consequence of its combination with other metallic bases, besides that of iron. In the experiments just described, ] had employed a prussiate of potash, in its mild state, without being sufficiently aware of the quantity of the oxide of iron, which it held in solution. Some of the metals also, and particularly the zinc, antimony, and manganese, contained iron, as is frequently the case ; and some of the acids employed to dissolve them, con- tained it also, as frequently happens. From all these sources of error, of which I ought to have been more mindful, I ascribed, as Fabroni and many others had done, the property of giving a blue colour with Prussian colourable matter, (which, as far as I know, belongs only to iron) to metals which do not possess it. — Could I find that property in any other matter, PERMANENT COLOURS. VI But the most remarkable, and, probably, the most useful, effect of these applications was, a very full, striking, lively colour, of which I cannot by words give my readers a perfect idea, because I do not remember to have ever before seen any colour exactly like it, and there is, I believe, no name in any language suited to it. It approaches nearest, however, to the highest and brightest colour of new copper, but inclines more to the red, and is accompanied with a kind of metallic shining lustre, which, in my eyes, appeared very agreeable. This colour (which I .shall call the red prussiate of copper, until a better name be given to it) was pro- duced by the different solutions of copper in the sulphuric, the nitric, the muriatic, and the acetous, acids, separately ; and particularly well by that in volatile alkali. But the most re- markable circumstance attending the produc- tion of this new colour, was its extraordinary permanency, which was such, that though all the alkalies decompose the Prussian colourable matter when combined with iron, they have no effect upon its combination with copper; and the stability of the new colour is such, that should eagerly recur to, and make trials of it, in the hope of being thereby enabled to communicate and fix the blue, under consideration, upon broad-cloth, &c. with greater evenness than has yet been found practicable with the basis of iron. 02 PHILOSOPHY OF neither acids,* nor washings with soap, how- ever numerous, nor exposure to weather for the longest space of time, seem capable, in the least degree, of diminishing either its body or its lustre ; and, therefore, I cannot help thinking, that it may prove highly useful, and more es- pecially for calico printing, by way of topical application upon cottons, and, perhaps, in dye- ing cotton-yarn for stripes of muslins, borders of handkerchiefs, &c. I have not experienced the same effect by applying a direct mixture of the Prussian colouring matter with a solution of copper, not even when T put the prussiatc of ammonia into a solution of copper by ammonia, (which I thought most likely to answer J ; but have always found it necessary, cither to apply * I have since found, that by twenty-four hours immersion in the oxymuriatic acid, this colour was nearly decomposed j the Prussian colour being mostly separated, and the oxide of copper made green. But this fact affords no reason to doubt of its permanency for all the useful purposes in question. I found also, that a nitrate of silver, which contained a little intermix- ture of copper, being dropped upon cotton, stained or impreg- nated with the red oxide of copper, changed it to a beautiful greenish yellow ; and that a nitro-muriate of gold, applied to cotton so stained, changed it to an orange. This, and the former pieces of cotton being dried, and afterwards washed with soap, that to which the nitro-muriate of gold had been applied, assumed a deep violet, and very fast colour; and that with the nitrate of silver, became green, probably in conse- quence of the copper, by which the silver had been alloyed, and that contained in the red prussiate of copper. PERMANENT COLOURS. 03 the Prussian colouring matter (dissolved by potash, soda, ammonia, or lime) first to the linen, cotton, or silk, and after suffering it to dry, to apply some one of the before-mentioned solutions of copper; or else to apply the me- tallic solution first, and then the prussiate; but in this last method, I have not found any solu- tion of copper answer so well, unless it be that by ammonia, or volatile alkali. Some years after the publication of my dis- covery of the red prussiate of copper, it en- gaged the attention of M. Proust, who satis- fied himself, as I have since done, that to pro- duce this red colour, it is necessary to impreg- nate the colourable Prussian matter, or a prus- siate of potash, or lime, or ammonia, with that portion of black oxide of iron, which has been already mentioned, as necessary to enable the red oxide to become blue— and that a simple prussiate, destitute of the black oxide, though it unites with the oxides of copper, will only produce a yellowish brown colour; and I think, from my own experiments, that the colour in question is made to approach nearer to the bloodied by a little increase of the proportion of black oxide, beyond what would strictly be necessary to produce a Prussian blue with the red oxide of iron.* * About the year 1802, the Journals of the Royal Institu- tion, and ssvcml periodical works, announced that Mr. Hatchett 94 PHILOSOPHY OF With cobalt the simple prussiate gives a cin- namon brown, less approaching to the blood red, than the prussiate of copper with the black oxide of iron : with an oxide of mercury this prussiate gives a. yellow, sometimes inclining to the olive; and with gold, it gives a fine yellow, Having nothing more to offer concerning ani- mal adjective colours, I shall next proceed to vegetable. had discovered a very durable and useful pigment in the prussiate of copper, and without any mention of ray name, though 1 had, ten years before, not only discovered this pigment, but what was of much greater difficulty and importance, the ways of fixing it permanently, by topical application, upon linen, cotton, silk, &c. and had published my discovery eight years before, in a volume, of which one thousand copies were in the hands of the public. — I hope I shall not be thought improperly anxious to do myself justice on this subject, when it is considered, that I have suffered ten years to elapse without any mention of it, even in private conversation. PERMANENT COLOURS. 95 PART III. Of Vegetable adjective Colours. CHAPTER I. Of the Reseda luteola Lin. or Weld Plant, and some other Vegetable Yelloxvs. " Lutei video honorem antiquissimum, in nuptialibus flammeis totum conccssum : et fortassis ideo non nuinerari inter principals, Ijoc est, communes maribus ac foeminis, quoniam societas principatum dedit." C. Plinii secund. Hist. lib. xxi. 8. By this quotation from Pliny, we learn, that the yellow dye, though highly esteemed from remote antiquity, was exclusively appropriated to the use of women, and that the veil which brides wore on the wedding day, was entirely of that colour. The weld plant seems to have been employed to dye yellow, at least as early as the time when Virgil wrote his Eclogues ; for the latum men- tioned in his fourth, (line 44) was, doubtless, the reseda luteola, which grew wild in Italy, as it does now in various parts of Europe; though the cultivated plant, which is smallest, abounds most in colouring matter. There are some varieties of this plant ; and of these one was formerly put into my hands, which had been 9S PHILOSOPHY OF imported from Hamburgh ; of which the stalks were not a fourth part so tall, or so large, as those of the plants cultivated in England and France. I did not, however, discover any considerable superiority in the quality of its co- louring matter, though in regard to quantity it yielded more than four times as much as an equal weight cither of English or French weld. This smaller variety, according to my informa- tion, grows, and is used by the dyers, in several parts of Germany. Weld requires the growth of nearly two sum- mers before it comes to maturity, and the crop is besides liable to fail from so many causes, that it cannot be a desirable object of agricul- ture in Great Britain. Indeed, it will not come to maturity in the northern parts of this island, and the expence of transportation is so great, by reason of its bulk, that the calico printers of Lancashire, Carlisle, Glasgow, &c. could not have exercised their art, either so advan- tageously or so extensively as they have done, if my discovery of the properties and uses of the quercitron bark, (to be meii^« ned in the next chapter) had not come to their relief, and more- over afforded them other important benefits. To give a full yellow colour to wool or silk, twice its weight of either English or French weld is deemed necessary ; and from the extent of space which the stalks of the plant occupy, PERMANENT COLOURS. 97 (the roots being useless) it is necessary to ex- tract the colour separately, previous to the dyeing operation ; which, however, must take place s oon after such extraction, as the decoction w ill otherwise speedily undergo a decomposition, sufficient to render it useless. The old hook translated from the Dutch, and printed, as before mentioned, in 1605, directs the employment of stale urine and wood ashes with water, to extract the colouring matter of this plant, which was afterwards to be fixed on linen by verdig'rise instead of alum, though the latter appears to have been employed as the mor- dant for wool ; and this practice seems to have subsisted ever since, with but little alteration. Wool, or woollen cloths, are commonly pre- pared for the weld yellow, by boiling them the usual time with a fourth or fifth of their weight of alum, and a twentieth of their weight of tar- tar ; which last is supposed to render the colour a little more delicate and lively; and the yellow may be farther improved by adding, either to the preparation, or the dyeing liquors, a small portion of the muriate, nitro-muriate, or murio-sulphate of tin. Linen thread, or cotton yarn, are commonly prepared for the weld yellow, by copious im- pregnations with the aluminous basis, to which a little lime or chalk is sometimes added ; a VOL. II. H 98 PHILOSOPHY OF little powdered verdigrise is also sometimes mixed in the dyeing or weld liquor. * Weld appears to contain a large portion of potash, neutralised chiefly by phosphoric and malic acids. In topical dyeing, or calico printing, very little less than the heat of boiling water will suffice to fix the colouring matter of weld ; and the parts wanted to be kept white, are then so much stained by it, and this stain is so diffi- cult to remove, that, during the damp cloudy weather which generally prevails in winter, four or five weeks exposure on the grass will hardly prove sufficient for that purpose. This is a serious inconvenience which does not attend the use of the quercitron bark, and which has caused the latter to be generally employed by ca- lico printers to almost the total exclusion of the former; though, it was their only resource for dyeing j^ellow, until the recent introduction of quercitron bark. Weld also produces another bad effect when employed for topical dyeing upon linens or cottons, which have previously received madder colours ; for in this case, the weld yellow, by a particular affinity, applies and fixes itself upon these colours so copiously as to change their appearance, and tarnish their lustre greatly ; and this is another defect, PERMANENT COLOURS. V9 From which the bark is nearly, if not wholly, exempt.* By the Act of the thirteenth of his present Majesty, ch. 77, the sum of 20001. was granted to Dr. Richard Williams, as a reward for his in- vention of a fast green and yellow dye on cotton yarn and thread. This supposed fast dye was given with weld, by the help of a mor- dant; the composition of which (that foreigners might not enjoy the benefit of it) Dr. Williams was permitted to conceal, and to supply the cotton and thread dyers with the mordant at a certain price. I have, however, reason to believe, that it was either a solution of tin alone, or of tin and bismuth, which enabled the weld yellow, as it enables that of the quercitron bark, to bear the action of acids and of boiling soap- suds, though unable to bear the action of sun and air. This defect, however, was not rea- dily discoverable by the method which Dr. Williams employed to obtain a favourable testi- mony from the dyers on this subject. His * The opaque yellow, employed for paper hangings, is obtained by mixing clean white calcareous earth, with a solu- tion of alum, sufficient in quantity to convert the former into a saturated sulphate of lime, which subsiding along with the alurnine, forms a basis for the colour ; and this basis is made yellow by applying to it a strong decoction of the tops and seeds of the weld plant, and it is afterwards dried and formed into cakes. H 2 100 PHILOSOPHY OF method was that of weaving the dyed yarn into pocket han kerchiefs, so as to produce yel- low stripes or borders, and giving them to be worn in the pockets of those who were afterwards to attest the goodness of his dye; and as handkerchiefs inclosed in a pocket are not exposed to the sun and air, the defect in question was not perceived until some time after the reward had been paid for a supposed invention of no value, and of which, I believe, no use is now made. Art. 2d. Rhus cotinus, Lin. or Venice su- mach, improperly called young fustic, is a shrub growing principally in Italy and the South of France ; whence the root, as well as the stem or trunk of the shrub, deprived of the bark, are brought and employed (after being chipped) for dyeing a full high yellow, approaching to the orange, upon wool or cloth, prepared either with alum or the nitro-muriate of tin. But the colour obtained ,by these means has been always deemed very fugitive. I find, however, that this defect, in regard to the last of these mordants, may, in a great degree, be 'obvia- ted, by employ ing tartar along with the nitro-muriate of tin. Four pounds of the rhus cotinus chipped, afford no more colour than one pound of the quercitron bark. This ap- pears to be the shrub mentioned by Pliny, (lib. xvi. cap. 8) as growing in the Appenines, and called cotinus. PERMANENT COLOURS. 101 Art. 3d. The rims coriara; elm-leaved, or common sumach of Spain, Portugal, and other parts of Europe, as well as of North America, affords a yellow dye with the aluminous hasis ; but so pale that it is but little employed for the purpose of giving a yellow colour only ; it, how- ever, possesses another species of colouring mat- ter, similar in most respects to that contained in galls, which renders it useful for drab and dove colours in calico-printing, and also capable of dyeing black with iron and the solutions of that metal : this species of colouring matter, and the application thereof, upon wool and cotton, will be treated of in their proper places. The prin- cipal uses of sumach with quercitron bark, in calico printing, will be noticed in the next chapter. Employed by itself in this way, it gives a troublesome stain to the white parts, which is obviated by using it with the querci- tron bark, and it is diminished when used by itself, by employing only a very moderate heat, in which calico, printed with acetite of alumine and iron liquor, of different degrees of strength, will receive yellow, black, and grey colours, sufficiently lasting. There are several other species of sumach, which grow spontaneously and abundantly within the United States of America, and pro- duce colours similar to those of the rhus coria- ra; particularly the rhus glabrum, called scarlet sumach, from the colour of its acid berries 102 PHILOSOPHY OF which are produced in clusters, and used by the aborigines of North America as mordants to fix the red colour of a species of gallium, with which they have long dyed their porcupine quills; also the rlius typhinum, called Virginian sumach, the rhus copallinum, or lentiscus* leaved sumach, &c. The bark of the roots, stems, and woody branches of all these shrubs contains a large pro^- portion of that species of colouring matter, which gives a black colour with iron, and which was erroneously supposed to distinguish and belong exclusively to what have been called astringent vegetables: but for dyeing yellow, the colouring matter of the leaves and young green shoots is greatly preferred ; and in the countries where sumach is cultivated tor the use of dyers, the stems are never allowed to become woody, the young shoots being cut down every summer, and ground up with the leaves. I formerly endeavoured to concentrate the colouring matter of sumach (with the tannin which accompanies it) by reducing it to the form of a dry extract, for the use of dyers and tanners, but I found it strongly disposed to deliquate or attract moisture ; probably, from the malic acid which seems to abound therein. In regard to the colouring matter of the wood of the large stems of the old full-grown shrubs, it seems, in all the species, to resemble that of the rhus cotinus, (Venice sumach op PERMANENT COLOURS. 103 fustic) mentioned in the preceding article, and in my experiments has produced exactly similar effects. Pliny mentions (lib. xxiv. c. 11.) the leaves of sumach, which he calls rhus erythros, as being employed instead of pomegranate rinds to pre- pare skins, (leather) and the berries as being used instead of salt, to preserve and season, or give relish to meat — and the savages of North America formerly employed the berries of their scarlet sumach for the same purposes. Art. 4th. Moms tinctoria, Lin.* called impro- perly old fustic by the English, and bois jaune by the French, is a large tree growing naturally in Jamaica, Porto Rico, Tobago, and almost all the other West India islands; its wood is of the colour of sulphur, and has, within two centuries, been brought into general use as a dyeing drug, though the yellow colour, which it affords with an aluminous basis, is neither high nor bright ; it has, however, the advantage of being durable, and of not being thrown down or made latent by acids so much as the weld and quercitron yel- lows; and for this reason it is now very com- • The fruit of this tree in size and shape resembles the white mulberry ; and like other mulberries, has its acini both within jnd without the pulp, which are of a greeniih colour. Whilst unripe, the fruit is milkey j but at maturity it is luscious- ly sweet Birds feed on the fruit, and by dispersing, plant the eeeds. 104 PHILOSOPHY OF monly employed (chipped or ground) in dyeing Saxon greens upon cloth, with the sulphate of indigo, as mentioned at pages 337 and 338 of vol. i. ; the muddinessof its yellow being of but- little detriment to the full dark greens most frequently dyed with it in this way. It is also very much employed for dyeing drab colours upon cloth, and especially on cotton- velvets, fustians, &c. with an iron basis, and olives with a mixture of this and of the alumi- nous basis, as will be mentioned in the succeed- ing chapter, where so much will be found re- specting the means and modes of employing the quercitron bark to produce similar colours, which it does with equal advantage, that 1 shall add but little more upon this subject. Four pounds of this wood chipped, yield about as much colouring matter as one pound of the quercitron bark , and allowing for this difference of quantity, it may be employed for general dyeing with the several mordants or bases proposed for the bark ; remembering always that they diow colour which it affords, can never be made to acquire any thing like an equal degree of clearness and brightness with that of the bark or of the weld ; and for this, with some other reasons, it is not likely to be ever employed in calico printing.* * Since this was first printed. M. Chaptal has foond means, which will be mentioned presently, to obviate the muddiness of this yellow, in a great degree. PERMANENT COLOURS. 105 I am not yet able to ascertain whence the word fustic was derived to our language. Venice sumach appears to have been long distinguished in France by the name of fustet, and I suspect that our dyers with the wood, introduced the name, and changed it to fustic ; such changes having frequently happened in other cases. The moms tinctoria being afterwards brought from America, and also employed for dyeing yellow, and being destitute of a name, appears to have likewise acquired that of fustic ; and a confusion hiving arisen by thus giving the same name to two different species of wood, a distinction was improperly created by calling that of the Venice sumach, young fustic, (as being manifestly the wood of a small shrub,) and that of the moms tjictoiia, (which is always imported in the form of large logs or blocks) old fustic. At w r hat t.me these epithets were first applied, to create t lis distinction, I have not discovered ; but they must have been in general use, at least 130 years ago; because Sir William Petty, in an account V of the Common Practices of Dyeing," which he gave to the Royal Society when first institu- ted, mentions Venice sumach under the name of "young fustic," and the moms tinctoria under that of " old, 11 as being their common and appropriated names. In this way, however, many persons have been misled, so far as to conclude, that two very distinct dyeing drugs (the one a 1 06* PHILOSOPHY OF small European shrub of the sumach kind, and the other a large American tree of the mulberry kind) were the same, or differing from each other only in point of age. The French have, indeed, avoided this source of error, by leaving the Venice sumach to bear exclusively the name of justet, and giving that of bois jaune, or yellow wood, to the morus tinctoria ; and, perhaps, it might be well for us, even now, to call the latter yellow wood, or dyers mulberry , in order to avoid the error in question. This wood, like some others, contains both a resinous and an extractive colouring matter, and both appear to be mixed with a portion of tannin, or the tanning principle, which tarnishes the yellow of the colouring matters, and M. Chap- tal has lately found (See Memes. de lTnstitut, torn, i.) that glue, when added to a decoction of this wood, precipitated the tannin, and thereby enabled the superincumbent liquors to dye yellows almost as bright as those of weld and quercitron bark. The wood known in England by the name of green ebony, possesses a species of yellow colouring matter very similar to that of the morus tinctoria in dyeing, and is sometimes employed in its stead. Art. 5th. The unripe berries of the rhamnus infectorius of Linnaeus, are called French PERMANENT COLOURS. 107 ^berries, and chiefly employed for preparing a lively, but very fugitive, yellow for topical appli- cation in calico printing.* Cotton printed with the aluminous mordant, and dyed with these berries, instead of weld or quercitron bark, receives a full bright yellow ; but in this and every other way it fades so speedily, that the use of it should not be tolerated, whilst there are other means of giving nmchmore durable yellows. There is a particular species of the rhamnus, growing in Candia, and other parts of the Levant, yielding berries larger than those brought from the South of Fiance ; they are distinguished by the name of Turkey berries, and preferred to the French, though the colours of both are fugitive. Great quantities of them are exported from Salonica, to which they are brought from Thessaly and Albania. Art. 6th. Saw-wort, serratula tinctoria, Lin. affords a good substitute for weld in dyeing upon * M. Duhamel asserts, that the French berries, or grains d'Avignon, are produced by the rhamnus infectorius, which (a* well as the rhamnus saxatilis and other species) certainly pro- duces berries giving a yellow colour. But professor Martyn, in his Edition of Miller's Gardeners' Dictionary, contends that these berries are the fruit of the narrow-leaved alaternus, a shrub which grows abundantly in the South of France ; and he asserts, that having collected its berries, and shown them to several dealers in the article, they offered to buy them as French berries. 108 PHILOSOPHY OF the aluminous basis, with which it communicates a bright lemon yellow of considerable durability. The common preparation with alum and tartar, is to be employed for this yellow upon wool and cloth ; or if a brighter colour be wanted, the preparation may he given with nitro-mut iate of tin, (dyers spirit,) and half as much tartar. For giving a very inferior yellow upon coarser woollens, the dyers broom (genista tinctoiia, Lin.) is sometimes employed, with the common preparation of alum and tartar. Art. 7th. All the five species of erica, or heath, growing on this island, are, I believe, capable of affording yellows much like those obtained from the dyers' broom — their colours may, indeed, be raised and brightened by the solutions of tin; but when this has been done, they have, with me, always proved fugitive. This I have also found to be the case of the yellow, dyed with the bark and shoots of the Lombardy poplar, (populus dilata, or pyramidalis,) recommended by Mons. d'Am- bourney, though they are poor in colouring mat- ter, seven pounds weight of them being required to dye a single pound of wool. Art. 8th. The American golden rod, (solidago canadensis, Lin.) affords good yellows to wool, silk, and cotton, upon the aluminous basis. Hel- lot seems to have been the first who attempted, though without success, to introduce this plant into general use as a yellow dyeing drug; and PERMANENT COLOURS. 109 Messrs. Gaad and Succow have since made the like attempts with no better success ; though I can affirm, from the results of many trials, thatit would prove a very advantageous substitute for the weld in calico printing; the colour which it affords in this way, to parts printed with the aluminous mordant, being in no respect inferior, and the stain or discolouration produced upon the un printed parts, being much less and much more easily discharged than that of weld. The plant (golden rod) is aUo more rich in colour, and capable of being raised with great ease. It grows natural ly in abundance, almost every where, between Carolina and Hud- son's Bay. Kalm says, that the three-leaved hellebore, (helleborus trifolius,) called tissavoyanne jaune, by the French in Canada, is there used by the Indians in giving a fine yellow colour to several kinds, of work, which they make of prepared skins ; 'and that the French having learned this from them, dye wool and other things yellow with this plant. Besides these, there arc many other vegetables capable of affording adjective yellow colours, both with the aluminous basis and that of tin, particularly the seeds of purple trefoil, lucerne, and fenugreek, the flowers of French marygold, the chamomile, (anthemis tinctoria,) the ash, (fraxinus excelsor,) the fumitory, (fumaria 110 PHILOSOPHY OF officinalis,) the leaves of the sweet willow (sali x pcntaiidria,) the verbascum thapsus, Lin. the agrimonia eupatoria, or common agrimony* the bidens tripartita, or trifid water hemp agrimony, the leaves and branches of the lemon tree (citrus,) and others, which need not be named, because they are not likely to be ever considerably employed. Besides these, Loureiro mentions the fibraurea tinctorea, a climbing shrub, and pterocarpus flavus, a large tree, both growing in the woods of China and Cochin- china, and affording yellow dyes ; as does the fruit of the gardenia florida. He also men- tions the roots of the morinda umbellata, as being employed in Cochinchina to dye cloth of a permanent saffron colour. Ventenat has described a species of tagetes (papposa)growing on the banks of the Mississipi, and affording, as he says, a durable yellow dye. The Elder Michaux observed in the western division of the Tenesee country, (North America) a species of sophora, nearly related to the sophora japonica, employed by the Chinese as a yellow dye, and conceived that it might become an object of great importance. The younger Michaux adopting this idea, sent a parcel of the wood to M. Chaptal, then Minister of the Interior in France, and he soon after gave me a sample of it, (when I met him in South Carolina in the year 1802,) which, though it had PERMANENT COLOURS. Ill been purposely made very small, enabled me to satisfy myself that it could never maintain any sort of competition with the quercitron bark. Professor Woodhouse, of Philadelphia, men- tions the hydrastis canadensis as imparting to silk '■ a rich and superb yellow colour," and he afterwards gives an account of many experi- ments which he had made with the xanthoriza tinctoria, but concludes it by stating as his opinion, that, " that truly valuable dyeing drug, the quercitron bark, will always supersede the xanthoriza, arid every other native (i. e. Ameri- can) yellow dye." There is, indeed, so much difficulty in always producing the exact shades of colour which dyers are required to imitate, that the use cf various materials for obtaining similar effects must alw r ays prove highly inconvenient. A i'cw drugs occupying but little space, rich in colour- ing matters, and capable of being always ob- tained, as well as extensively applied, by sadden- ing and otherwise diversifying their respective colours, are to the dyers most needful and use- ful : by being constantly occupied with a few such drugs, they acquire that degree of dexterity and certainty in the use and management of them, which alone can prevent disappointment in the nice operations of this art. — Such a drug is the quercitron bark, which will be the princi- pal subject of my next chapter. 112 PHILOSOPHY OF CHAP. II. Of the Properties and Uses of Quercitron Bark. " II n'y a pas de propriety plus respectable que lcs decovcrtes de " l'indiistrie." Berthollet, Ann. de Chytnie, tome vi. The Quercitron bark is produced by the quer- cus nigra of Linnaeus,* which might now be more properly denominated quercus tinctoria;f * The name of quercitron was given by me to this species of oak, and derived from the Latin words, qwercus citrina, which I thought more suitable than the denomination of Linnaeus : and being so given, the name was adopted and sanctioned by an Act of Parliament, of the 33d year of his present Majesty, (entitled an act for allowing the importation of quercitron, or black oak bark, &c.) and it has become the prevalent name in France, Germany, and other parts of Europe. f Since this was first printed in 1/94, the elder Michaux, has adopted the name of quercus tinctoria, in his " Histoire des Chenes de l'Amerique, ou description ei Jigurts de toutes les especes et varietes de chenesde l'Amerique septentrionale, &c. par Andre Michaux, Membre Associe de l'Jnstitut National de France, &c." Paris, 1801, folio. In this work the author describes 20 species of American oaks, of which his J 3th is that which affords the quercitron bark. His character of it, is " Quercus foliis petiolatis, subtus pubescentibus, lato-obo- valibuJ, leviter, et subrotunde lobatisy basi obtusis : cupula subscutellata, aut turbinata ; glandedepresso-globosaaut ovata." Of this species he makes two varieties. 1st. " Chene Quercitron, a feuilles angulensis, — great black PERMANENT COLOURS. IIS and is one of the objects of a discovery, of which the use and application for dyeing, calico- printing, &c. are exclusively vested in me, for a term of years, by an Act of Parliament passed in the 25th year of his present Majesty's? reign.* oak— Champlain black oak." He represents this tree as growing from lake Champlain to Georgia, always in a good soil, and at some distance from the sea ; and as rising from 60 to 80 feet high, with a trunk from 6 to 10 feet in diameter, in Georgia j but smaller northward. This is the variety which I have en- deavoured exclusively to introduce as a dye. His second variety is " Chene quercitron a feuilles sineueuses." Having sinuated leaves, and growing chiefly in the low parts of Georgia and South Carolina. Theyellowcolouringmatter of this species is combined with another, which gives a brownish tinge, or tint, called/awe by the French ; a circumstance in which it agrees with what I suppose to be the quercus aquatica, or water oak, of Catesby. * About four years after this paragraph was written and pub- lished, the term of the act in my favour expired ; but as I had, dur- ing its continuance, exercised my rights mere liberally and be- neficially for the public, than providently towards myself and family, and as I had, moreover, been frustrated of a great part of my just profits, by various infringements of this act, and by obstructions and losses resulting from the war, a bill was intro- duced, and passed by the House of Commons, in the 39th of his present Majesty "for enlarging, for the term of seven years, and continuing the powers" of the former act in thy favour : This bill (or act of the House of Commons) was, however, lost in the House of Lords, by a postponement of the second read- ing, in consequence of the opposition of a great number of persons in the Northern parts of the Kingdom, who had greatly profited by my discovery, and of whom some had grown riek vol. II. I 114 PHILOSOPHY OF The bark of this tree appears to consist of three parts or coats. and powerful in a considerable degree from it. And thus,with- ont being heard by my counsel; who were in attendance, or being allowed to repel, as I was prepared to do by adequate testimony, the groundless allegations of my opponents, and though more than three-fourths of the Calico Printers, and consumers of the quercitron bark, in the Southern parts of the kingdom, had petitioned the House of Lords for the prolongation in question, I was left with very little remunera- tion for the labours of a great part of my life ; excepting the consciousness of having done good to many persons, who appeared to be neither sensible of, nor grateful for it. I have, however, long since forgiven my opponents. Most of them had been made to believe that my profits were five times greater, than they were in truth ; and that their own interests would be greatly promoted by this termination of my rights; though many of them had previously certified under their hands, that the advantages resulting from my dis- covery had been greatly increased by the beneficial manner in which these my rights were exercised : and this fact was strongly asserted by the petition, just mentioned in my favour, in which the Petitioners declare that they " have never expe- rienced any inconvenience from the exercise of any of the rights vested in Dr. Bancroft, by the act formerly passed in his favour ; but, on the contrary, are convinced that they have been invariably exercised upon a plan of all others the most con- ducive to the public good, and at the same time with such liberality, that the inconveniencies usually attending monopo- lies have been thereby avoided." " That although dyeing-woods and drugs from America have generally risen since the war began, and some of them to more than five times their former prices _; and although, from the great abundance of colouring matter in the quercitron bark^ and its useful properties, joined PERMANENT COLOURS. 115 1st. The epidermis, or external coat, through Which the several excretions of the tree arctrans- to a great addition to the cost thereof, and more especially to the freight and 'Charges attending its importation during the last six years, Dr. Bancroft might have been entitled and enabled to advance the price of the said baik, in a proportion at least, equal to that of other dyeing drugs, or woods from America, yet he has invariably supplied your Petitioners, and other con- sumers thereof, at the very lowest price, to which it had been reduced by him before the present war, and by so doing, has relinquished the fair profits of his invention, to a greater amount than any profit which lie is likely to make, by supply- ing this bark for a farther term of seven years, at the low price intended to be fixed for the same, by the bill in ques- tion." The Petitioners moreover declared themselves " fully per- suaded, that it would be safest and most advantageous for them- selves, and other consumers of the quercitron bark, to con- tinue secured of sufficient supplies thereof, during a farther term of seven years, at the low price intended to be fixed for the same by the bill in question, and thereby exempted from those frequent variations and augmentations of price, which might otherwise be expected, so long, at least, as the war should continue, by the practices of those who, from time to time, might find means to engross the said bark." — That this per- suasion had been well-founded, was soon proved by the event, for in less than twelve months this bark rose to three times the price at which it lud been ifl variably supplied by me, and at which I should have been bound to supply it, for another term of seven years, if the bill had become a law ; and it has on the average been at nearly double that price to the present time. — This is the only instance, I believe, in which an invention ever became more costly, after the expiration of a monopoly, grauted to remunerate the inventor, than i,t was during the l 2 "U<5 PHILOSOPHY OF mitted, which, in part at least, adhere to its outer surface, where they harden, and become almost black y by condensation, and probably by an ab- sorption of oxygene ; and hence the Linnaean denomination of black oak has originated ; that great naturalist having had no knowledge of the properties of this bark in dyeing. 2d, The middle or cellular coat, in which the colouring matter principally resides; and, 3d, The interior or cortical part, consisting chiefly of lamina, formed by the re-union of different vessels, which become more hard and fibrous, as they are placed nearest to the woody part of the tree, and have, therefore, less room to contain the colouring matter. The epidermis, or exterior blackish coat of this bark, affords a yellow colouring matter, which, however, is less pure, and more inclined to a brownish hue, than that of the other coats or parts; and it ought, therefore, to be separated by shaving. When this is done, and the re- maining cellular and cortical parts are ground by mill-stones, they will separate partly into a light fine powder, and partly into stringy fila- ments or fibres, which last yield but about half as much colour as the powder, and, therefore, care should be always taken to employ both to- continuance thereof, and it has demonstrated, most incontrover- tibly, that my opponents were greatly deceived, and that I was greatly wronged. PERMANENT COLOURS. 117 get her, and as nearly as possible in their natural proportions, otherwise the quantity of colour produced may either greatly exceed or fall short of what is expected. The quercitron bark thus prepared and proportioned, will generally yield as much colour as eight or ten times its weight of the weld plant, (reseda luteola, Lin.) and as much as about four times its weight of the chipped old fustic (moms tinctoria, Lin.) : but the colouring matter of the bark, in its nature and properties, most clearly resembles that of the weld plant; with this advantage, however, that it is capable alone of producing more cheaply, all, or very nearly all, the effects of every other yel- low dyeing drug ; and, moreover, some effects which are not attainable by any other means yet known. The quercitron colouring matter may be rea- 1 dily extracted by water, even when it is only blood warm ; but if the infusion be strained and left at rest, a small portion of resinous matter will separate and subside in the form of a whitish powder, capable of giving colours similar to those of the non-subsiding parts or particles. The clear infusion being evaporated, will afford an extract which, when completely dried, has, I think, commonly weighed as much as about one- twelfth of the bark from which it was obtained, and yields nearly as much colour as the whole of the bark. But it has been found very difficult IIS PHILOSOPHY OF to make this extract in any large quantity, so as to render it capable of giving colours equal in beauty to those obtained directly from the bark itself; because, if the evaporation be rapidly per- formed, with a considerable degree of heat, the colour always becomes tarnished, probably by a combination of oxygene, producing effects simi- lar or approaching to those of a slight com hustion ; and if the evaporation be conducted slowly., the colouring matter surfers greatly by another change, like that to which the decoction of v. eld is always liable, and by which the latter usually spoils by keeping, even in less than 24 hours. There are several varieties of the Qaercus nigra, all containing a portion at least of the sa ne species of colouring matter; but some of thtm, (particularly the qucrcus nigra digitata,* and * This seems to be Miehaux's 2d variety, or " Chene qier- citron feuilles sineueuses ;" of which a cargo was imported f om South Carolina about the year 1785, by one of those who, a>out that time, infringed my rights ; and its bad effects threw sime discredit upon the true quercitron bark, by its being mistiken for the latter. The oaks of America are, however, so numerous, and s< apt to vary the forms of their leaves ly age, that it is often dificult to distinguish one from the other, at least by their leaves. The younger M!c ! aux, after stating the quercitron oak tobevery common in the Northern States, and Westward of the Allegiany mountains, though but rare in the lower parts of North and South Carolina, and Georgia, says, that the leaves of its bwer branches affect a form different from the upper ; " Celhs ci PERMANENT COLOURS. 119 the quercus nigra trifida, both of Marshal,) besides the yellow, contain a species of the fauve, or fawn colour, which tarnishes the yellow, and in calico-printing, occasions another (be observes,) sont plus profondement echancrees," and he adds, that the figure of this oak in the " Histories des Chenes," &c. represents only the leaves of the lower branches, and of the young trees. He mentions, however, as a means of distinguish- ing this oak, that in all the other species " le petiole, les nervu- res, et les feuilles elles memes, sont d'un vert plus ou moins fonce," and that towards autumn this colour darkens, and be- comes more or less red. But that the same parts in the " quercitron, sont dans le printems jaunatres, et comme pul- verulentes," and that this yellow colour becomes the more marked as the winter approaches. He also mentions another peculiarity, which will point out the oak in question, when the leaves are fallen in winter j and this is the litter taste of its bark, and the yellow colour which it gives to the saliva when chewed. He adds, indeed, (what he mentioned to me in 1S02) that he thought he had observed nearly similar properties in the bark of the quercus cinerea ; but this last species may always be known from the other, because it grows only in the most dry arid spots of the Southern States, with lanceolated leaves, and seldom attains more than 18 feet in height, with 4 inches in diameter, whilst the quercus tinctoria, or quercitron oak, often rises 80 feet above the ground, and its leaves have each several lobes. See Voyage a L'Ouest des Monts Alleghany, &c. par F. A. Michaux, M. D., &c. By order of the French government, M. Michaux sent to France large quantities of the acorns of the quercitron oak, from which great numbers of plants have been produced in the nursery of Trianon, and in other places, with a view to the lark hereafter. 120 PHILOSOPHY OF bad effect, that of staining those parts of the cotton or linen intended to be kept white, so as to make the bleaching of them afterwards very difficult. The barks of these last mentioned varieties have sometimes been mixed with that of the better sort, and in considerable quantities, (through the ignorance or the inattention of la- bourers employed in the collection.) so as to bring discredit upon this new and truly valuable d\ eing drug : but there is reason to hope, that such im- proper mixtures will hereafter be avoided, ia consequence of the very particular instructions which have been given for that purpose. The decoction of quercitron bark appears to be of a yellowish brown colour, which is dark- ened by alkalies, and rendered lighter by acids; alum dissolved in it, separates but a small portion of the colouring matter, which subsides in the form of a deep yellow precipitate. Either the muriate, the nitro-muriate, or the murio- sul- phate of tin, mixed with a decoction of the bari, produces an exceedingly beautiful lively yellow, and occasions a much more copious precipitation than the alum ; probably because the calx of tin is heavier, and unites with the colouring matter in a much larger proportion. Sulphate of iron, dissolved by a decoction cf this bark, produces a copious dark olive prec- pitate, and the clear supernatant liquor remains of a light olive green. Su'phate of copper in the like decoction, oo PERMANENT COLOURS. I2i casions a precipitation which is of a yellow in« clining to the olive, and leaves the supernatant liquor of a yellowish green. The effects of other bases and chemical agents upon the colouring matter of the bark, so far as they appear of any importance, will be disco- verable from the following account of its various uses in dyeing and calico-printing. Of the application of Quercitron Bark for the Dyeing of Wool and Woollen Cloths, with an Aluminous Basis. Wool, and the cloths or stuffs made from it, ought, in all cases, to be scoured before they are dyed, in order to separate a kind of grease with which the fibres are naturally covered. This is usually done by immersing the wool or cloth for about a quarter of an hour in stale urine, di- luted with three times as much water, and kept nearly of a scalding heat ;* it is afterwards to be thoroughly rinced in clean water, and then dyed or impregnated with the proper mordants for dyeing, without any previous drying, that the colour may apply itself more equally. Alumine, or the earth of alum, precipitated by clean potash, and repeatedly washed in pure water, being boiled with quercitron bark, rea- dily united with its colouring matter, and pro- * See more on this subject at p. 86 of Vol. I. 122 PHILOSOPHY OF ciuced a yellow inclining very much to the golden, or, as it is called, the yolkey hue; and wool boiled in this mixture for the space of half an hour, took a brownish yellow which, however, seemed to have been but superficially applied, the earth of alum, in its undissolved state, not being ahle sufficiently to enter the pores of the wool, even when they are distended hy boiling water. The earth of alum, dissolved by the vegetable, the fossil, and the volatile, alkalies separately, as well in their mild as in their caustic states, was found to dye yellow colours of different shades, with the quercitron bark upon wool; but they were all inferior to those given by the same basis (alumine) when dissolved by acids. The cheapestand most simple method of apply- ing the quercitron colour upon wool, is that of boiling up the bark with its weight, or a third more than its weight, of sulphate of alumine, (common alum) in a suitable portion of water for about ten minutes, and then dyeing therein the wool or cloth previously scoured, as before men- tioned, taking care to give the higher colours first, and the paler straw colours afterwards. In this way yellows not wanted to be very full or bright may be dyed very expeditiously and cheaply ; and they may afterwards be conside- rably raised and enlivened, by passing the wool or cloth, unrinced, a few times through hot water, PERMANENT COLOURS. 12* into which a little clean powdered chalk has been previously stirred, in the proportion of about a pound or a pound and a half of chalk for each iOOlb. weight of wool or cloth. The bark, when used in dyeing, (being first ground,) should always be tied up in a linen bag, of a loose open texture, and suspended in the dyeing liquor by a cord, with which it may be dragged occasionally backwards and forwards through it, to extract and spread the colouring matter more equally. But when the bark and alum are boiled toge- ther and united in this way, the colour does not afterwards fix itself either so readily, or so copi- ously upon the wool or cloth, as when the alu- minousbasishas been first appliedseparately in the common modeof preparation ; and, therefore, this simple and cheap method of applying the quer- citron colour is only suited for straws and pale yellows, especially as there is reason to suspect, that the adjective colours of every kind are not so durable when died with an alumnious basis in this way, as when they are dyed upon a like basis previously conveyed into and fixed in the substance which is to be dyed. As often, therefore, as anv thing more than a pale yellow is intended to be given from the quercitron bark and the aluminous basis upon wool or cloth, the latter should be boiled in the common way, but without either tartar or argol, for the space of an hour, or an hour and aquar- i24 PHILOSOPHY OF ter, with about one-sixth or one-eighth of its weight of alum, dissolved in a suitable quantity of water, and then, without being rinced, it should be put into a dyeing vessel, with clean hot water, and about as many pounds of powdered bark, (tied up in a bag,) as there were used of alum to prepare the wool or cloth, which is then to be turned, as usual, by the winch through the boiling liquor, until the colour appears to have taken sufficiently ; and then about one pound of clean powdered chalk for every lOOlb. of the wool or cloth, may be mixed with the dyeing liquor, and the operation continued eight or ten minutes longer, when the yellow will have become both higher and brighter by this addition of chalk. The yellows given in this way from the quer- citron bark are infinitely better, and considera- bly cheaper, than any which can be given from old fustic with an aluminous basis : indeed, they approach nearly to those given by weld with the common preparation of alum and tartar, and are in every respect as durable ; though it mus: be confessed, that they have less of that liu-ly greenish, or lemon hue, for which the weld yel- lows arc particularly valued : this, however, nay be readily and cheaply obtained, in the utnost perfection, from quercitron bark, by means which will hereafter be explained. Wool or cloth, which has been first properly dyed blue in the common indigo vat, may be PERMANENT COLOURS. 125 made to receive any of the various shades of green which are usually given in this way from weld, by boiling the blue wool or cloth, (after it has been well rinced,) in water, with about one- eighth of its weight of alum, as just directed for producing a yellow, and afterwards dyeing it un- rinced, with about the same quantity of bark, and a little chalk, which should be added towards the end of the process, as already described. Greens of less body may be dyed with smaller portions of bark and alum. In the same way, cloth which has previously received the proper shade of Saxon blue, may be dyed of a beautiful Saxon green : it will be proper, however, for this purpose, that the blue cloth should be first very well rinced to separate, as far as water will do it, the acid which may have been imbibed from the sulphate of indigo, and which has a strong tendency to throw down and weaken the quercitron as well as the weld yellows. Butas mere rincingin waterwill separate- only a small part of this acid from the cloth, (with which it combines in a certain degree,) it will be proper to add about three pounds of chalk, with ten or twelve pounds of alum, for the preparation liquor of 1001b. weight of cloth, which is to be turned and boiled as usual for about an hour; and then, without changing the liquor, ten or twelve pounds of bark, powdered and tied up in a bag, may be put into it, and I2<5 PHILOSOPHY OF the dyeing continued, taking care frequently" to agitate t'>e lag, in order that the colour of the bark may spread equally through the liquor. It will be found, however, that the yel- lowwill manifest itself but slowly in thiswav, by reason of the sulphuric acid imbibed with the blue colour, joined to that of the alum in the preparation liquor, which the portion of chalk; before mentioned, will not have been sufficient to overcome; and, therefore, when the dyeing with bark has continued about fifteen minutes, it will be proper to add another pound of clean pow- dered chalk, stirring it well through the liquor, and to repeat this addition afterwards once, twice, and even three times, at intervals of six or eight minutes, if the colour does not rise sufficiently without it. By these additions, the quercitron yellow will manifest and apply itself abundantly and equally, so as to produce very beautiful greens, which, by varying the proportions of indigo, as well as of bark and alum, may be varied at pleasure. The chalk, in this case, does not merely answer the purpose of separating the acid left in the cloth by the sulphate of indigo and the alum, but, by uniting with this acid, it becomes a sulphate of lime, and fixes itselfj in part at least, as a basis in the fibres of the cloth, where it helps to raise the colour, and also to render it a little more durable. At present the Suxon greens are commonly dyed with the oM PERMANENT COLOURS. \2i fustic, because the colour of this wood is not thrown down by acids so much as that of the bark and weld : and this difference enables the dyer, when he has extracted the fustic colour by previous boiling, to mix the sulphate of indigo therewith, and dye the cloth green by one ope- ration, after it has been prepared as usual with alum and tartar. The process, however, which I have mentioned for doing this with bark, is full as cheap and as expeditious, and the green pro- duced will be more beautiful, because the quer- citron yellow is much more bright and clear than that of fustic. Atpages 83and 84 of thisvolumclhave describ- ed a method of combining the Prussian blue and the epiercitron yellow upon analumnious basis, so as to produce a beautiful green colour, which I had flattered nryself might be advantageously employed upon wool : further trials, however, have manifested so much difficulty in applying the colour equally, that I shall say no more of this combination at present. Durable yellows may also be dyed upon wool, with either the muriate, the nitrate, or the ace- tite of alumine, but not with any superiority of colour which could compensate for the increased expence of these aluminous preparations. 128 PHILOSOPHY OF Of the best Methods of dyeing upon Wool and Woollen Cloths with Quercitron Bark and the Tin Basis. In Chapter IV. of Part II. I have mentioned the different effects of some of the preparations of tin in exalting the colour of the quercitron bark, as well as that of cochineal ; and it will be remembered that, for this purpose, I found the muriate and the murio-sulphate of tin, pre- ferable to any other of the preparations of that metal ; I observed, however, that the former of these had an injurious action upon the fibres of wool and cloth, unless when sparingly and care- fully employed, and was, therefore, less proper for general use than the solution of tin, made by a mixture of muriatic and sulphuric acids, as described at page 483 of my first volume ; to which my readers will be now pleased to recur. In order to dye 1001b. weight of cloth or wool- len stuffs of the highest and most beautiful orange yellow, only 101b. weight of quercitron bark, and the same weight of murio-sulphate of tin, will be required ; the bark powdered and tied up in a "bag, may be first put into the dyeing vessel with hot water, for the space of six or eight minutes, then the murio-sulphate of tin may be added, and the mixture well stirred for two or three minutes ; after which the cloth may PERMANENT COLOURS. 129 be put into the dyeing liquor and turned briskly for a few minutes: the colour applies itself in this way, so equally to the cloth, and at the same time so quickly, that after the liquor begins to boil, the highestyellow may be produced in less than fifteen minutes, without any danger of its proving uneven. High shades of yellow, some- what approaching to those dyed from bark, in the way just mentioned, are frequently given with the rhus cotinus, (commonly, though improperly, called young fustic,) and the dyers' spirit, or nitro-muriate of tin ; but the colour so given, is less beautiful and more fugitive, as well as more expensive, than that obtained from the bark, as just described. When a very bright golden yellow, approach- ing less to the orange, is wanted, seven or eight pounds of murio-sulphate of tin, with about five pounds of alum, and ten pounds of bark, will suffice for 1001b. of cloth; the bark being first boiled a few minutes, then the murio-sul- phate of tin, with the alum added, and the cloth afterwards dyed, as just directed. Pure bright yellows, of less body, may be produced by empbying smaller portions of bark, murio- sulphate of tin, and alum, in the same w r ay : and, indeed, all the possible shades of pure bright yellow may be given, with the utmost ease and certainty, by only varying the proportions of these ingredients. But where it is expedient to VOL. II. k 130 PHILOSOPHY OF give that lively, delicate greenish tinge, which, for certain purposes, is so much admired, and^ which the weld alone has been supposed capable of giving, white argol, or tartar, must be also employed with the bark, murio-sulphate of tin, and alum, in different proportions, according to the particular shade intended to be given. Thus, e.g. for a full bright yellow, delicately inclining to the greenish tinge, itwill be proper toemploy about eight pounds of bark, and six pounds of murio-sulphate of tin, with six pounds of alum, and four of clean white tartar, or cream of tartar ; a little more alum and tartar will render the yellow more delicate, and give it more of the greenish tinge ; and where this clean, lively, delicate greening tinge is wanted in the greatest possible perfection, it will be proper to use the bark, murio-sulphate of tin, alum, and tartar, all together in equal quantities. These last deli- cately-greenish lemon yellows, are but very seldom, if ever, wanted to be dyed of much ful- ness or body, and therefore ten pounds of bark> and the like quantities of murio-sulphate of tin, alum, and tartar, will generally prove sufficient to dye three or four hundred pounds weight of cloth or woollen stuffs of the colours in question; for which purpose the bark is to be first boiled a few minutes in water only, then the other ingredients are to be added, and mixed in the liquor by stirring, and a few minutes boiling, PERMANENT COLOURS. 131 and afterwards the cloth put into the liquor (first cooled a little) and turned briskly through it until the colour appears sufficiently raised. The pieces intended for the highest shades should be always dyed first, and those for weaker shades afterwards. When about two-thirds of the whole quantity of cloth has been dyed, it will generally be found, that the liquor, by continu- ing to extract colouring particles from the bark, has acquired an over-proportion of the latter, and wants a small addition of murio-sulphate of tin, alum, and tartar, (perhaps a pound of each,) to enable it to give the same delicately pale, though lively, greenish tinge, as at first : and indeed, a surer way of giving these very pale greenish shades with exquisite delicacy and beauty, is to boil the bark with a small propor- tion of water in a separate tin vessel for the space of six or eight minutes, then add the murio-sulphate of tin, alum, and tartar, and boil them all together for about fifteen minutes, and afterwards put a little of this yellow liquor into a dyeing vessel, previously supplied with water sufficiently heated, and the mixture being pro- perly stirred, to begin dyeing the cloth as usual, adding farther supplies of the yellow liquor from the first vessel, by a little at a time, as fast as it may be wanted. In this way the palest and most delicate shades may always be dyed with ease and certainty ; and those who have never K 2 152 PHILOSOPHY OF seen the effects of this process, will hardly con- ceive the exquisite beauty and delicacy of these pale, but lively, greenish lemon yellows, which certainly costless than any similar colours given, if such can be given, by any other means. Weld is unquestionably the only dyeing ware capable of producing effects similar to those of the bark in this respect, and at the average price it will prove nearly four times as costly, regard being- had to the smaller portion of colour which it affords, besides the expence of long boiling, which the bark does not want, to extract its colour. Indeed, it may generally be computed, that the yellows dyed from quercitron bark, with murio-sulphate of tin and alum, do not cost, in dyeing materials, more than one penny for each pound of cloth, and that in time, labour, and fuel, they do not cost half as much as those usually given by other means. And this is also true of the more delicate shades given by bark, murio-sulphate of tin, alum, and tartar ; for though this last ingredient be expensive, it is wanted only for the paler colours, which require smaller portions of dyeing materials, and, there- fore, do not cost more than the highest shades given without it. A greenish tinge may, indeed, be produced without tartar, by employing in its stead, a little verdigrise dissolved by vinegar along with the bark, &c. but I think it is neither so lasting PERMANENT COLOURS. 133 nor so delicately clean and beautiful as that pro- duced by the use of tartar. The sulphate of in- digo will also produce this greenish tinge, if em- ployed in a very small quantity with the bark, murio-sulphate of tin, and alum ; but it has a tendency to fix itself so quickly upon the fibres of wool or cloth, that great care is necessary to hinder it from taking unequally, and the tinge produced by it is, moreover, somewhat liable to cast or fly, as the dyers say, in the finishing part ; whilst the greenish tinge result- ing from the use of tartar, as before directed, will leave the press perfectly clear and bright. Indeed, the colours obtained from quercitron bark by these means, are very durable ; they withstand even the action of strong mineral acids, and of boiling soap-suds, as well as ex- posure to air. This last, indeed, they are prin- cipally enabled to resist by the good effects of alum, and more especially of tartar. Since the highest yellows, which approach very nearly to the orange, and which are best dyed either with muriate, or murio-sulphate of tin, and bark, though they bear the action of soap and of acids in a wonderful degree, are liable, after some time, to lose a considerable part of their lustre, and acquire a brownish complection by exposure to the sun and air. This is also true of yellows dyed with nitro-muriate of tin (dyers' spirit) as a mordant, not only when employed with the 134 PHILOSOPHY OF bark, but with weld, and in a greater degree with fustic and otber yellow vegetable colour- ing matters. In some of which this defect is not so well obviated by alum and tartar, as it is in the quercitron and weld yellows. I must here remark, that tin, by whatever means dissolved, when applied as a basis for dyeing wool, renders the fibres a little harsh ; so that they never run so far nor so easily in spinning as they would otherwise do, and the wool itself is apt to appear coarser ; which is one reason for not dyeing scarlet in the fleece, and it may be one for not dyeing wool yellow with any of the solutions of tin as mordants, until it has been woven, or at least spun ; though, I am persuaded, this defect is in a great degree ob- viated, by employing the murio-sulphate of tin, with a mixture of alum, or of alum and tartar, and combining these with the colouring par- ticles of the bark, (in the ways which I have described,) before they arc applied to the wool or cloth. When yellows not quite so lively and beau- tiful can be made to answer, a much smaller proportion of the sulphate of tin will prove sufficient; five pounds thereof, for instance, may be boiled with ten pounds of bark, ten pounds of alum, and two or three of tartar, and the cloth dved as before directed. The decomposition and recomposition which result PERMANENT COLOURS. 185 from a mixture of tartar with murio-sulphate of tin, will be readily conceived from what has been mentioned on this subject in the preceding chapter. By using very small proportions of cochineal with the bark, murio-sulphate of tin, &c. the co- lour may be raised to a beautiful orange, and even to an aurora. Madder also employed in this way, raises the quercitron yellow, but the effect is less beautiful than with cochineal; and this is also the case when madder is employed with weld. At pages 381 and 382 of my former volume, I have made some mention of the means of dyeing woollen cloth topically or partially ; and since that time I have found, that by mixing a strong decoction of the bark, with a suitablepro- portion of murio-sulphate of tin, &c. and thick- ening the mixture, as for the pro-substantive topical yellows, hereafter to be described, for calico-printing, then applying the mixture by a pencil to the woollen cloth, covering the pen- cilled parts with paper, so as to prevent the moist colour from spotting the other parts, after- wards folding up the cloth, and tying it in a bag made of that kind of oiled linen, which is used for bathing caps, so as to exclude water, and then keeping it immersed in boiling water for a quarter of an hour, a full and beautiful yellow was fixed upon the parts which had beeu 130 PHILOSOPHY OF pencilled, without any farther running or spreading of the colour. The same mixture pencilled upon cloth which had been previously dyed* Saxou blue, produced a beautiful green where it had been pencilled. Diluted sul- phate of indigo pencilled upon scarlet cloth, and treated in the same way, produced a full black ; and it seems to be easy, by em- ploying proper mixtures in this way, to pro- duce all the varieties of colours topically upon woollen stuffs: as far as I can judge, the oiled linen, which, I believe, was never before employed for this purpose, is much more suitable to it than any means now in use. The most beautiful Saxon greens may be produced very cheaply and expeditiously by combining the lively yellow which results from quercitron bark, murio-sulphate of tin, and alum, with the blue afforded by indigo when dissolved in sulphuric acid, as for dyeing the Saxon blue. To produce this combination most advanta- geously, the dyer, for a full- bodied green, should put into the dyeing vessel after the rate of six or eight pounds of powdered bark, (in a bag) for every 1001b. weight of cloth, with only a small proportion of Mater, as soon as it begins to grow warm ; and when it begins to boil, he should add about six pounds of murio-sulphate of tin, (with the usual precautions,) and a few PERMANENT COLOURS. 137 minutes after, about four pounds of alum; these ha\ itig boiled together five or six minutes, cold water should be added, and the fire dimi- nished so as to bring the heat of the liquor nearly down to what the hand is able to bear; and immediatel} after this, as much sulphate of indigo is to be added as will suffice to produce the shade of green in. ended to be dyed, taking care to mix it thoroughly with the dyeing liquor by stirring, &c. ; and this being done, the cloth previously scoured and moistened, should be ex- peditiously put into the liquor, and turned very briskly through it for a quarter of an hour, in order that the colour may apply itself equally to every part, which it will certainly do in this way with proper care. By these means, very full, even, and beautiful greens, may generally be dyed in half an hour; and during this space, it is best to keep the liquor at rather less than a boiling heat. Murio-sulphate of tin, is infi- nitely preferable, for this use, to the dyers' spi- rit; because the latter consists chiefly of nitric acid, which by its highly-injurious action upon indigo, would render that part of the green co- lour very fugitive, as I have found by repeated trials. But no such effect can result from the murio-sulphate of tin; since the muriatic acid has no action upon indigo, and the sulphuric is that very acid which alone is proper to dis- solve it for this use. 138 PHILOSOPHY OF Respecting the beauty of the colour thus pro- duced, those who are acquainted with the un- equalled lustre and brightness of the quercitron yellows, dyed with the tin basis, must neces- sarily conclude, that the greens composed there- with will prove infinitely superior to any which can result from the dull muddy yellow of old fustic: and in point of expence, it is certain that the bark, murio-sulphate of tin, and alum, necessary to dye a given quantity of cloth in this way, will cost less than the much greater quantity (six or eight times more) of fustic, with the alum necessary for dyeing it in the common way ; the sulphate of indigo being the same in both cases. But in dyeing with the bark, the vessel is only to be filled and heated once ; and the cloth, without any previous pre- paration, may be completely dyed in half an hour; whilst in the common way of producing Saxon greens, the copper is to be twice filled; and to this must be joined the fuel and labour of an hour and an half's boiling and turning the cloth, in the course of preparation, besides nearly as much boiling in another vessel to ex- tract the colour of the fustic, and after all, the dyeing process remains to be performed; which will be equal in time and trouble to the whole of the process for producing a Saxon green with the bark; so that this colour obtained from bark will not only prove superior in beauty^ PERMANENT COLOURS. 139 but in cheapness, to that dyed as usual with old fustic. Mr. Darhbournay, in the supplement to his cc Recueil de proced^s et experiences sur les teitures solides," &c. mentions various experi- ments made by him with the quercitron bark, from which he concludes, that in order to pro- duce the good effects which I had previously described as resulting from its use in dyeing woollen cloths, these should be first impreg- nated with a tin basis, and then dyed in the man- ner which I had directed. In this way, says he, I obtained full shades of that beautiful yellow, a little greenish, but very durable, (" de cc " beau jaune un peu verdatre et tres solide,") which is so well suited to produce a fine green, cither by the indigo vat, or by the composition for Saxon blue, i. e. sulphate of indigo. And having applied this latter by the common mode of dyeing, to cloth which had previously received the quercitron yellow, and also to cloth dyed yellow with the Lombardy poplar, (which, in other respects, he greatly* commends,) he found that the former which had received the hark yellow, took a fine dragon green, (" un beau " vert dragon,") and the latter nothing better than a greenish olive. It is true that Mr. Dam- bournay computes the expence of dying with the quercitron bark, as greatly surpassing that of dye- ing with the Lombardy poplar. But his com- HO PHILOSOPHY OF put at ion was founded on very erroneous suppo- sitions, joined to the circumstance of his calcu- lating the muriatic acid to cost near two shil- lings and sixpence sterling the pound weight, which is more than six times its real cost ; though this may, probabty, have been nearly the price which it bore in France, whilst the gabelle sub- sisted there. The nitro-muriate of tin, (dyers' spirit,) though it produces good yellows with querci- tron bark, produces them in a much weaker degree than the murio-sulphate of that metal ; which is really the cheapest, and most effica- cious, of all the solutions or preparations of tin, for dyeing the quercitron as well as the cochi- neal colours. The sulphuric acid by itself dissolves, or ra- ther calcines, a large portion of tin, if allowed to act upon it for any considerable time; and this solution, joined to the bark, with alum and tartar, produces bright strong yellows on cloth, though I think they appear less soft and beau- tiful, than those dyed either with the muriate, or murio-sulphate of tin. This metal dissolved, or rather calcined, by a mixture of the nitric and sulphuric acids, is still less suitable for dyeing with the bark. Tin dissolved by muriatic acid, to which one- third of its weight of clean white tartar had been previously added, produced a very bright PERMANENT COLOURS. 141 and delicate yellow with the bark, upon cloth, and this, by longer boiling, was raised to a full and beautiful orange. Tin dissolved in strong nitric acid, (double aqua fortis,) with an addi- tion of one third of its weight of tartar, also produced a very good yellow, though somewhat inferior to the last. Upon putting tartar, with a portion of tin, into a glass vessel with strong colourless sul- phuric acid, the latter, or rather its oxygenous part by combining with the inflammable part of the tartar, immediately rendered the mixture as black as ink ; and the solution of tin pro- duced by it, was found of but very little use as a mordant for dyeing with the bark. The oxyd of tin, produced by the action of the nitric acid upon that metal, contains a large portion of oxygene; and yet it raises the quer- citron yellow : but when this oxyd is dissolved in muriatic acid, it produces only a very feeble life- less yellow with bark; though tin not previously oxygenated will, when dissolved by the same (muriatic) acid, act most powerfully in exalting the quercitron yellow : which seems to prove, that this defect of colour does not result from the presence of oxygene alone, but from its combination with muriatic acid. A similar effect was also produced by employing tin cal- cined by sulphuric acid, and then dissolved in the muriatic, as a mordant with the bark. 142 PHILOSOPHY OF Cloth boiled in water with the muriate of tin and tartar, has sometimes been made yellow, and sometimes of a cbesnut brown, only from the action of this mordant, unassisted by any colouring drug. These discolourations seem to depend upon the particular state of. the cloth, as being more or less freed, either from the natural swint of the wool, or the grease com- monly applied to it for particular purposes. Dis- colourations of this kind are not easily removed ; they withstand the action of sun and air for a considerable time, and if cloth so discoloured be dyed with either bark, or with cochineal, the colour will appear tarnished ; for which reason the application of muriate of tin, with tartar only, as a mordant, ought to be avoided, unless the dyer be very certain that the cloth has pre- viously been perfectly well scoured. A few lumps of the dry oxyd of tin, men- tioned at pages c 2 14 and 215 of the former volume, having been finely powdered and mixed with a suitable quantity of decoction of querci- tron bark, the mixture was found capable of dyeing a very full and bright yellow upon wool- len cloth. The colour, however, being exposed to the action of sun and air, very soon acquired a brownish complexion. Some of the same oxyd of tin reduced to powder, having been washed in warm water, to remove the adhering acid, as far as water could remove it, was found PERMANENT COLOURS. MS to be still capable of combining with the colouring matter of the bark, so as to dye cloth yellow; especially when the oxyd had been pre- viously suffered to remain mixed with the decoc- tion of bark, for some hours, in a warm situa- tion. Cotton also took a vellow colour bv dyeing in this mixture ; but it was easily re- moved by washing with soap, and therefore was, I think, only applied superficially. I have but little to offer respecting the use of copper, or rather of the oxides and solutions of that metal alone, as mordants or bases for dyeing with quercitron bark on wool or cloth. Their general effect is to raise and fix the quercitron yellow ; but at the same time to give it a greenish or rather an olive tint. Wool dyed with a tenth of its weight of bark, and half as much sulphate of copper, received an agreeable colour, between the yellow and the olive. The bark, with muriate of copper, seemed to impart but little colour to wool for some time; but a little chalk being added, a full yellowish olive was pro- duced. This also proved to be the case, when nitrate of copper was employed with the bark, until chalk had been added ; and then the wool speedily imbibed a yellow, delicately inclining to the olive hue. Verdigrise with the bark produced a yellowish olive on wool ; which, by theadditionof chalk, was brightened, and made 144 PHILOSOPHY OF to approach nearer to the yellow. These colours appeared to be sufficiently lasting. Drab colours of various shades may be most expeditiously and cheaply dyed by the querci- tron bark and an iron basis. For this purpose the bark may be boiled a few minutes in a copper vessel, with one-third, or one-fourth of its weight of sulphate of iron, (copperas,) according to the shade required, and the liquor having been well mixed, and a little cooled, the cloth may be dyed therein as usual ; but with- out any other preparation than that of scouring and moistening. To sadden and darken the colour still farther, a little sumach, (rhus coria- ria,) may be added with the bark; and on the other hand, the colour may be inclined to the olive and yellow, by diminishing the quantity of sulphate of iron, and employing with it a little alum and chalk; or (which is better) a little sulphate of copper, with or without a small pro- portion of chalk. Or the cloth may be first turned a few times through a vessel, with boil ing bark liquor, then taken out, and turned briskly through a vessel with hot water, in which a suitable proportion of sulphate of iron has been dissolved, with or without either alum and chalk, or sulphate of copper and chalk, as the particular colour intended to be given may require. In either way the colours will prove lasting, and the expence very small ; four or live PERMANENT COLOURS. at pounds of bark being generally sufficient to dye one hundred pounds weight of cloth, of the colours in question. Cloth prepared by previous boiling, with one-twentieth of its weight of sulphate of iron, and One-fourth of that quantity of chalk, and then dyed in bark liquor, became of a strong durable chocolate colour ; but in this way great care is necessary to render the colour even. Cloth prepared by boiling with a twentieth of its weight of sulphate of iron, half as much sea- salt, and one-fourth of that quantity of chalk, and then dyed with bark, received a very lasting dark brown colour. Cloth dyed with quercitron bark, sulphate of iron, and sulphate of manganese, in small pro- portions, became of a light, but pleasing, drab colour; which, by the addition of a little chalk, was afterwards changed to the cinnamon. Cloth prepared with nitro-muriate of gold, and dyed with bark, became of a delicate olive yellow. The solutions of bismuth, zinc, antimony, silver, mercury, lead, and platina, by different acids, produced various shades of' brown, yellowish brown, brownish yellow, cin- namon, drab, and olive colours ; of which it is not expedient to give my readers a particular description, because they either may be all more cheaply obtained by other mordants, or are not likely to be brought into use. VOL. II. J 146 PHILOSOPHY OF Cloth boiled in water, with one-twentieth of its weight of sulphate of lime, and dyed with bark, received a strong nankeen colour. Ni- trate of lime in this way, produced a nutmeg brown ; and the muriate of lime produced a very full and lasting drab colour, which, in some respects, may be preferable to the drabs given by an iron basis, and especially as being less likely than the latter to injure the texture of the cloth. Of the Properties and Uses of Quercitron Bark in dyeing upon Silk. All the different shades of yellow, commonly dyed upon silk from weld, may be obtained with equal facility and beauty, and more cheaply, by employing the bark in its stead, after the rate of from one or two pounds for every twelve pounds of silk, according to the particular shade of colour wanted. For this purpose the bark, pow- dered and tied up in a bag, should be put into the dyeing vessel whilst the water is cold, and as soon as it becomes a little more than blood - warm, the silk, previously alumed, should also be put in and dyed as usual ; and where the higher yellows are wanted, a little chalk or pearl- ashes may be added towards the end of the ope- ration, as mentioned for the dyeing of wool. Where shades of yellow, more lively than any which can be given either by weld or bark with PERMANENT COLOURS. W the aluminous basis 011I3 7 , are wanted, it will be advantageous to employ a little of the murio sul- phate of tin ; and but a little of it, because the calx of tin, unless sparingly used, always diminishes the glossiness of silk. To produce the shades in question, it will be sufficient to boil, after the rate of four pounds of bark with three pounds of alum and two pounds of murio-sulphate of tin, with a suitable quantity of water, for ten or fifteen minutes, and the heat of the liquor being afterwards reduced so that the hand can bear it, the silk is to be put in and dyed as usual, until it has acquired the proper shade, (which it will do speedily,) taking care, however, to agitate the liquor constantly, that the colouring matter, which would otherwise subside in a considerable degree, may be kept equally dispersed through the liquor. By adding suitable proportions of sulphate of indigo to this yellow liquor, and keeping it well stirred, various and beautiful shades of Saxon green may be dyed in the same way very equally and cheaply. Tie shades intended to incline most to the yellow should be first dyed, and afterwards, by adding more sulphate of indigo, these partaking more of the blue may be readily produced ; and, indeed, nothing can be more commodious or certain than this way of dyeing the most beautiful Saxon greens upon silk. L 8 148 PHILOSOPHr OF* By dissolving different proportions of copperas, or copperas and alum, in the warm decoction of bark, silk may, in the same way, be dyed of all the different shades of olive and drab colours; and other varieties may be produced with the bark generally, b}' employing the same means which are used to produce the like variations with weld. Of the Application of Quercitron Bark to the Fibres of Linen or Cotton, either woven or spun, by general Dyeing. I here use the term general dyeing as opposed to that partial or topical application of colours on which calico-printing chiefly depends. At pages 90 and 9], of my former volume, I have endeavoured to explain the causes which render adjective colours less durable on linen and cot- ton than they are on wool or silk, so far, at least, as these causes depend on differences in the structure and chemical properties of the suj- stances in question ; but whether my explanation be well founded or not, this at least is certain, that the attraction between the aluminous basis and the fibres of linen and cotton, is mu:h weaker than that which subsists between the same basis and the fibres of wool or of sik ; and this want of a sufficient attraction or affinity has made ir necessary to employ extraor PERMANENT COLOURS. 149 more copiously, and fixing it more firmly, than it otherwise would be precipitated and fixed upon the fibres of linen or cotton, in order to enable them to receive permanent adjective colours by dyeing. The principal of these means are certain oily and animal matters joined to some vegetable astringents, particularly galls ; all of which, I mean the former as well as the latter, evidently possess a strong attraction for alumine, and when united to linen or cotton, produce very beneficial effects, as is manifestly seen by the process for dyeing the Adrianople or Turkey red, concerning which Mr. Henry, M. Berthollet* and M . Chaptal, have published several very inge- nious as well as highly interesting observations 5 at present, however, I shall only notice these extraordinary means, so far as (hey seem likely to improve the beauty and durability of the colours capable of being communicated to linen or cotton from quercitron bark. The fibres of linen or cotton, when spun or woven, are prepared for the dyer by being first boiled in water with a suitable portion of potash, (which for linen should be made caustic, in order that it may act more strongly upon the oily and resinous matters abounding in flax,) and afterwards bleached by exposure upon the grass to sun and air. But as this operation com- monly leaves a portion of earthy matter in the linen or cotton, which, by being unequally 150 PHILOSOPHY OF distributed, would render any colour given by dyeing unequal ; the cotton or linen ought to be soaked or steeped in water, soured by sulphuric acid, to dissolve and remove this earthy matter, taking care afterwards to wash or rince off the acid, lest, being concentrated in the cloth or yarn when drying, it should injure the tex* ture. The method prescribed by the French regula- tions, and adopted in most European countries, for dyeing yellow upon linen or cotton from the weld plant is, by soaking the cloth or yarn in a liquor made by dissolving one-fourth of its weight of alum in as much water as is necessary for that purpose; to which it will be highly advantageous to add, after the rate of one pound of clean potash or ten ounces of chalk, for every six or seven pounds of alum,* to neutra- lize the excess of acid contained in the alum, and promote a separation of its earthy basis. The cloth or yarn having been thus soaked, is taken out of the alum liquor, and well dried ; and being afterwards finced, it is to be dyed in * Haussman says, that when English alum is dissolved in five times its weight of water, and one-eighth of its weight of chalk is added to saturate the excess of acid, a solution will be produced, which does not crystalize in summer, and but little in winter ; though without chalk it requires sixteen times as much water as of alum to make a permanent solution. PERMANENT COLOURS. 151 weld liquor made by boiling about one pound and a quarter of the plant for each pound of cloth or yarn ; which, after having received a sufficient body of colour, is to be taken out of the dyeing liquor, and soaked for an hour and more in a solution of sulphate of copper, (blue vitriol) containing after the rate of three or four ounces of the latter for each pound of cloth or yarn ; it is then to be removed, and, without being washed, put into a boiling solution of hard soap, containing in like 'manner three or four ounces of soap for each pound of cloth or yarn, in which it is to be well stirred and boiled for about three quarters of an hour or more, then washed and dryed. I have found, by repeated trials, that this mode of precipitating the calx of copper upon the yellow previously dyed from weld with an aluminous basis, renders the colour more durable, but, at the same time, gives it a darker complexion. And I have found similar effects where bark was used instead of weld j the colour dyed with the bark in this way having proved, in every respect, as good as that obtained from weld : but I am convinced, that whether the colouring matter be taken from the former or the latter of these vegetables, the yellow dyed in this way never is either so beautiful or so lasting as that partially given by calico-printers from the same vegetables, and which the dyers might readily give with equal perfection, by only employing the acetite of 152 PHILOSOPHY OF al umine, or aluminous mordant, described at pages, 359, "360, and 36 lj of my first volume; and'this more cheaply as well as more expedi- tiously than that produced by following the French regulations ; considering the expence of So much blue vitriol and soap as they require, and which may be rendered unnecessary by adopting the calico-printers' aluminous mordant. The best method of applying the aluminous mordant for general dyeing with quercitron bark (which I most earnestly recommend when- ever bright and durable yellows are wanted,) is as follows, viz. Take a sufficient quantity of the acetite of alumine, which for this purpose may be made by dissolving after the rate of only one pound of sugar of lead and three pounds of alum, as at the pages just quoted,* excepting only that it need not be thickened, and mix this liquor with an equal quantity of warm water, then let the linen or cotton (properly cleansed, as before mentioned) be thoroughly wetted and soaked in the mixture, which ought to be about blood- warm, for the space of two hours, then taken out and moderately pressed or squeezed over a proper vessel to collect what might otherwise drop or run off, and prevent an unnecessary waste of the aluminous liquor ; and this being * See also the cheaper means of preparing an acetite of alumine, mentioned in the note to p. 366 of Vol. I. PERMANENT COLOURS. 153 done, let the linen or cotton be well dried in a stove heat, where it can be conveniently applied, and then soaked again in the aluminous mordant, and again pressed or squeezed and dried as before; after which, without having been rinc- ed, let it be thoroughly wetted in as much, and only as much, lime water as will conveniently suffice for that purpose, and afterwards dried ; and where a very full, bright, and durable yellow is wanted, it may be well to soak the linen or cotton a third time in the diluted aluminous mordant, and after drying, wet it a second time with lime water, and dry it again : but in either case, the linen or cotton, after its last dyeing, should be well rinced m clean water, in order to separate any loose or unfixed particles of the mordant or basis, which otherwise might do harm in the dyeing vessel. The lime-water employed in this way, answers the purpose of producing a more copious deposition of the alumine in the fibres of the linen or cotton, and it moreover superacids a portion of calcarious to the aluminous basis ; an effect which is not without considerable utility. I have found, that when the aluminous liquor has been employed at a scalding heat, the colour afterwards produced was not so good as that which results from liquor only made blood-warm; the pores of linen and cotton being so open as not to require any distension by a greater degree of heat. 154 PHILOSOPHY OF The cotton or linen being prepared and rinced, as before mentioned, a small fire is to be lighted under the dyeingpan or vessel, previously supplied with the usual quantity of water, and the pow- dered quercitron bark tied up in a bag, after the rate of from twelve to eighteen pounds for every hundred pounds weight of linen or cotton, where full-bodied yellows are wanted, is to be put in, whilst the water is cold, and immediately after it, the linen or cotton is also to be put in, upon .sticks, if it be thread or yarn, or, if piece-work, on the winch, agitating or turning it, in either case, as usual, for the space of an hour, or an hour and a half, during which the water should gradually become warm, but not warmer than the hand can bear. When this time has elapsed, the fire may be increased, and the dyeing liquor brought to a scalding, and thence to a boiling heat ; in which it will be sufficient to let the cotton oi- lmen remain a few minutes only, when a bright lively yellow is wanted, because longer boiling always gives the yellow a brownish cast, what- ever vegetable may be employed indyeingit. The linen or cotton having thus acquired sufficient colour, is to be taken out, rinced, and dried as usual. When the colour of quercitron bark is slowly raised in this manner by a very moderate heat, the colouring particles seem to adjust themselves more accurately, and unite more intimately, to PERMANENT COLOURS. 155 those of the basis, and thereby to produce a co- lour more fixed and durable than it is when they are hastily accumulated by a boiling heat, and, perhaps, chiefly upon the surface of the substance dyed, and of the basis combined therewith. All the different shades of yellow may in this way be dyed from quercitron bark : if it be ued sparingly, with a very moderate heat, and the operation continued only for about half an hour, a pale, though livel), yellow will result ; if used more copiously, arid the operation continued somewhat longer, a fuller colour will be pro- duced ; and this may be raised higher and higher according as the heat and proportion of bark are increased and the dyeing operation prolonged, so as, indeed, to produce a very dark brownish yellow, if the liquor be made to boil for half an hour.* Pieces of cotton having been prepared with the printers' aluminous mordant and lime water, as already described, were dyed one with bark and another with weld, and being taken out of the dyeing liquors, a bit was cut off from each, * M. Chaptal appears to think that lime may be usefully em- ployed to extract, raise, and fix the colour of quercitron bark. He says, that having added quick lime to a decoction of this bark it produced ff un magma d'une magnifique couleur jaune, qui jouitd'uneassez forte fixite et dont on peut tirer une grande parti dans la teinture." See his Chimie appliquce aux arts. torn. iv. p. 460. i5o PHILOSOPHY OF and the remainder put back again into its liquor, in which a small quantity of sulphate of copper had, in the mean time, been dissolved, (after the rate of one ounce to five pounds of cotton,) and the liquors being nearly of a scalding heat; in about ten minutes the pieces were again taken out and found to have acquired a brownish com- plexion ; but, being exposed to the sun and air along with the bits which had been cut off before the sulphate of copper was added to the dyeing liquors, the brownish complexion of the former soon disappeared, and their remaining colour, at the end of four weeks, proved to be rather better than thatof the bits dyed without the sulphite of copper. It seems, therefore, probable, Uat a sparing use of the latter in tills way, may contri- bute something at least to the durability, if not to the beauty, of yellows dyed upon linen or cotton, after the application of acetite of alumine aid of lime, as before directed. When the aluminous mordant is empoyed without any addition of water, it may be suffi- cient to soak the cotton therein once only, and after dyeing to immerse itonce'm lime water then dry, rince, and dye it, as before mentioned. I think, however, that better effects result from, the application of a more diluted mordant, it two different times; and, indeed, I have found, tiat by immersing the cotton a great number of times alternately in the diluted aluminous mcrdant PERMANENT COLOURS. 157 and in lime water, and drying it after each im- mersion, the colour always acquired still more body and durability. At page 370 of my former volume, I have remarked, that by the East Indian method of calico-printing, the want of acetite of alumine is supplied by impregnating cotton with the astringent matter of yellow myrobalans, and with certain oily and animal substances, which enable the cotton, when a solution of alum is afterwards apply ed to it, to decompose and im- bibe a larger portion of alumine : and this prac- tice may be imitated in dyeing the quercitron yellow upon cotton, with so much advantage as to render the acetite of alumine in a great de- gree unnecessary, at least where the yellow is not required to be very clear and bright. Instead of myrobalans, (which are, however, to be found here,) the Alleppo galls may be em- ployed, choosing always the whitest for this use, because the browner might stain the cotton, so as to render it incapable afterwards of receiving a bright clear yellow ; and, perhaps, in this re- spect, the roots of at least two or three species of North American sumach, particularly the rhus glabra, Lin. might be preferable even to the whitest galls, by communicating less stain, and producing equally good effects, as I have found them to do in repeated trials. The best method of employing galls for this 158 PHILOSOPHY OF tlinary means for precipitating the alumine puvpose is, I believe, to boil after the rate of one pound of them, coarsely powdered, with half a pound of barilla, for the space of one hour, in two or three gallons of soft water, and then straining off the decoction to macerate thecotton an hour or two therein ; barilla, or rather the soda which it contains, enables the water to extract the astringent matter of the galls much more copiously than it otherwise could do; and being itself imbibed by the cotton, it also oc- casions a more plentiful deposition of alumine, when the cotton is afterwards put into a solution of alum, which, for this use, may be made by dis- solving eight pounds of alum and one pound of chalk in six gallons of water. In this calcareous solution of alum, the cotton, after being taken out of the decoction of galls and dried, is to be soaked for two hours, then taken out and dried ; then soaked a few minutes in lime watei, and having been again dried, it is to be immersed a second time in the calcareous solution of dum j after which, being again dried and well meed, the cotton is to be dyed slowly with the cuerci- tron bark, as before directed. In this wa; very full-bodied and lasting yellows maybe obtained, which will bear repeated washings with scap, as well as exposure to sun and air; and, the action of strong vinegar. By dissolving after the rate of one poind of PERMANENT COLOURS. 15 J) hard white soap, and half a pound of barilla, in three gallons of water, and macerating the cot- ton therein, as directed to be done with the de- coction of galls and sumach, then drying and immersing it in calcareous solution of alum, and afterwards proceeding, as just directed to be done after such immersion, I obtained a colour (with the bark) nearly as durable as when the decoction of galls had been used, and with the advantage of its not being thereby darkened. A pound of the yolks and whites of eggs, hav- ing been first beat up with an equal quantity of brown sugar, and then with two gallons of water, arid cotton having been soaked therein, instead of the solution of soap and barilla, then dryed ami immersed in the calcareous solution of alum; dried again and immersed in lime water, and then in the solution of alum, and afterwards rinced, and dyed with bark, as already described, it received a very full and lasting, though dark- ish, yellow colour. The animal mucilages in general, and some of the vegetable, being dis- solved in water and applied to cotton in the same way as the yolks and whites of eggs, just mentioned, produce the like good effects, and more especially the animal glue ; which appears to unite both with the cotton and the aluminous basis when used in this wav. A considerable time lias now elapsed since I was induced to try the effects of alumine com- • 160 PHILOSOPHY OF bined with other acids, besides the sulphuric and acetous, and also with potash, soda, and ammonia, both in their mild and their caustic states, as a basis or mordant for the quercitron colouring- matter. To separate aluminc from the sulphu- ric acid with which it forms common alum, this last compound may be dissolved in about eight times its weight of clean boiling water, and mixed with a filtered lixivium of clean potash, which should be added to the solution of alum gradually, until it no longer makes the liquor turbid, or occasions any further precipitation of alumine. The whole of the mixture may then be put into a canvas strainer to separate the fluid part, and this having been done, boiling water may be poured repeatedlyupon the re- maining moist alumine, and suffered to run through the strainer until the saline part of the mixture shall have been washed awa}', as far as it is capable of being washed away by water ; the alumine being then taken out and dried, will generally be found to weigh about one-fifth part of the weight of the alum employed to pro- duced: when thoroughly dried, the alumine con- tracts or shrinks greatly, and becomes at length so hard, that neither strong sulphuric or nitric acids can dissolve it, except with great difficul- ty and very slowly; and for this reason it ought always to be employed in a moist state, when intended to be again dissolved by any acid or PERMANENT COLOURS. 161 aline menstruum. Perhaps the great dispo- sition of this earth to contract or shrink by (Irving, may be one reason why it is generally most advantageous to convey and fix the parti- cles thereof as a basis in the pores of linen or cotton, first separately, and afterwards, when they have shrunk by drying, to superadd the adjective colouring matter, which may then find more space, and combine with the alumine in greater proportion than it could do when both, previously united, were applied together, whilst the particles of alumine were enlarged by mois- ture.* If moist alumine, obtained in the manner just described, be dissolved in either the nitric or muriatic acids, it will, by evaporation, afford crys- tals ; and those obtained with the nitric acid, by attracting moisture from the atmosphere, will prove deliquescent, unless kept in a vessel closely stopped. M. Berthollet found, that in these cases, the crystals depended on a remnant of sul- phuric acid, which always adheres to alumine, when separated in the wajy just described ; and * Another cause seems to be this, that when the colouring matter and the basis are first separately united, their affinities are exclusively exerted upon, and satisfied with>each other j and when they are afterwards applied to the stuff intended to be dyed, they have less attraction for it, and the size of their com- bined particles being increased by this union, they do not preci- pitate so far or so copiously. VOL. If. X 162 PHILOSOPHY OF that, by afterwards digesting it for some time in a solution of potash, or of ammonia, this adhe- ring sulphuric acid might be decomposed ; and that the alumine being then dissolved, either in the nitric or the muriatic acid, no crystals were pro- duced. It must, however, be remarked, that the alumine mentioned to have been employed in the succeeding trials, was obtained in the way first described, and, therefore, was not com- pletely divested of sulphuric acid. Having boiled a suitable portion of moist alumine with a decoction of quercitron bark during the space of half an hour, I attempted to dye both wool and cotton therewith, in order to see whether the undissolved particles of alumine, so united to the colouring matter of the bark, would become the basis of a lasting colour. I found, however, by repeated trials, that cotton in this way could only be made to imbibe a pale yellow, which, probably, adhered to the surface only of its fibres, because it was nearly destroyed by a single week's exposure to the sun and air. Wool, however, in this way received a brownish yellow, of sufficient body and considerable dura- bility. Ammonia, or volatile alkali, whether mild or caustic, appears to dissolve alumine so very sparingly, that hitherto I have found no consi- derable benefit from any solution of this kind as a mordant. Nor have I succeeded much better with either the carbonated (mild) potash, PERMANENT COLOURS. 163 or that of soda, their action not being consi- derable upon the earth of alum. But if this earth, obtained by precipitation and washing, as before mentioned, Ipe digested whilst moist with a strong lixivium either of potash or of soda, in its pure or caustic state, in a matrass placed on a sand heat, nearly approaching that of boiling water, it dissolves very copiously, and may afterwards, by evaporation, be made to crystalize. The celebrated Macquer appears to have believed, that very beneficial effects might be obtained in dyeing by" these combi- nations, and more especially when used as mordants for the madder red on cotton. It seems evident, however, that he was greatly mistaken respecting the true nature of those operations, upon which this belief was founded ; and that in the process for Turkey reds, where lie supposed the durability of* colour to .re- sult principally from a combination of this kind, no solution of aluminous earth by any alkaline menstruum could have taken place ; and though Mr. Haussman appears also to have formed considerable expectations of advan- tage from the application of these solutions of alumine by potash or soda, I have been led, by the results of many trials, to concur in opinion with M. Berthollet, that but little good is to be expected from them, unless it be under the circumstances which I shall m2 164 PHILOSOPHY OF presently explain, because the alkaline men- struum evidently has too much affinity to the particles of alumine to allow of their being deposited and fixed in the substance, to be dyed so copiously as is necessary ; and I have repeatedly found, that after having soaked cot- ton a sufficient time in the diluted solution of alumine by either potash or soda, the basis was almost wholly carried off, or removed by only rincing the cotton in water to fit it for being dyed, and that only very feeble colours could be raised upon what remained of the alumine as a basis. This was more especially the case where the solution of alumine had been made by potash, which, by attracting moisture from the atmosphere, rendered it difficult to dry the cotton sufficiently when impregnated there- with, at least without artificial heat. These defects were, however, removed, and a very excellent durable yellow produced, by putting the cotton, which had been first soaked, in a diluted solution of alumine by potash, into water which had dissolved as much common alum as it could retain, whilst blood-warm, ma- cerating and turning it therein for the space of half an hour, (during which the potash and sulphuric acid combining, each precipitates the alumine of the other,) then drying the cotton, and afterwards immersing it in lime-water; then drying again, rincing and dyeing it with the bark, as before directed. The yellow given in this PERMANENT COLOURS. 165 way faded but very little by two months ex- posure to sun and air in the midst of the Sum- mer; nor was it sensibly weakened by the action of strong French vinegar, or of the oxygenated muriatic acid. The solution of alumine by soda produced equally good effects in this way. Nitrate of alumine (made by saturating the nitric acid with moist alumine, as before men- tioned,) being dissolved in eight times its weight of water, and used instead of the solu- tion of common alum, last mentioned, produced a yellow rather better and more durable, even, than the last. Cotton, which had received no impregnation, being macerated in a like solu- tion of the nitrate of alumine, then dried, im- mersed in lime water, rinced, and dyed with the bark, received a yellow considerably better than I could obtain with a solution of common alum in the same way. Muriate of alumine generally produced with the bark, effects as good, but not materially better, than those resulting from common alum used in the same ways. In dyeing any of the yellows before mention- ed with bark, the colour may be raised to an orange by employing a suitable proportion of madder along with the bark. It can hardly be necessary for me to mention, that linen or cotton, either spun or wove, when previously dyed blue of a suitable shade in the 166 PHILOSOPHY OF usual ways, will be rendered green by supeiv adding the quercitron yellow in the ways, and by the means, already directed for dyeing tin yellow upon linens and cottons, not previouly made blue, taking care to proportion the quan- tum or body of each of the component blue and yellow colours to the particular shade of green which they are intended to compose or produce. Linen and cotton soaked four hours in a mordant made by dissolving lime in muriatic acid, and mixing the solution with six times its weight of water, afterwards dryed, rinced, and dyed with quercitron bark, took a full drab colour, which resisted the action of sun and air for a considerable time : but neither the sul- phate nor the nitrate of lime employed in this way with the bark, gave any thing more than buff or slight nankeen colours, of little durability. Magnesia dissolved by the sulphuric, the ni- tric, muriatic, and acetous acids, and used in this way as a mordant, produced, with bark, upon linen and cotton, weak drab, cinnamon, and nankeen colours, which, however, proved too fugitive to be of any use. Cotton, soaked in a diluted solution of flints, made as formerly mentioned, and afterwards rinced and dyed with the bark, became of a nankeen colour somewhat lasting. Among the metallic bases, that of tin might PERMANENT COLOURS. 167 be expected to produce benefical effects by general dyeing upon linen and cotton with the quercitron bark ; but hitherto my experiments therewith, though they have been very nume- rous and greatly diversified, afford no success- ful results : for though different solutions of tin, (particularly the nitro-muriatic and the murio-sulphuric,) when diluted and applied as mordants to linen and cotton, enabled these sub- stances afterwards to imbibe yellows exceeding all others in brightness, lustre, and beauty; and though these yellows are capable of resisting the action of boiling soap-suds, as well as of strong acids, not excepting the oxygenated muriatic acid, yet they decay very speedily when exposed to the sun and air, so as even to suffer more in a single week than the quercitron yellows dyed upon an aluminous basis com- monly suffer in a month. The tin basis is, moreover, accompanied with this singular cir- cumstance, that when applied separately to the linen or cotton intended to be dved, and when these substances, after the usual drying and rinc- ing, are dyed with the bark, the colour (con- trary to what happens with the aluminous basis) proves much more fugitive than it does when the solution of tin and decoction of bark are first mixed together, and afterwards applied to the linen' or cotton prosubstantively ; nor have I ever been able to apply any of the solutions of tin, even in small quantities, mixed with an 168 PHILOSOPHY OF aluminous mordant upon linen or cotton, with- out perceiving that the colour afterwards ob- tained thereby from bark, was much less durable in respect to sun and air, than it would have been with an aluminous basis only. Zinc, dissolved by different acids, and em- ployed as a basis for dyeing with quercitron bark on linen and cotton, produces brownish yellows, inclining more or less to the olive and drab colours; they seem, however, less dura- ble than the like colours, which may be more conveniently and cheaply given by substituting solutions of alum and of iron, mixed in diffe- rent proportions, as mordants. Bismuth being dissolved in nitro-muriaticacid, and the solution afterwards sufficiently diluted by water, and cotton being soaked therein for two hours, then immersed in lime-water, dried, rinced, and dyed with quercitron bark, it took a very high and full, but at the same time a brownish yellow, of considerable dura- bility. Copper, dissolved in the sulphuric, the nitric, muriatic, and acetous acids, and afterwards sufficiently diluted with water, being applied to linen and cotton as a mordant, enables them to obtain from quercitron bark, by dyeing, different shades of full, but brownish yellow,which, how- ever, does not long bear washing with soap, or exposure to rain, sunshine, and air; the oxyd of copper on which the colouring matter is ap- PERMANENT COLOURS, 169 plied, being readily acted upon by all these agents. Soaking the linen or cotton in* lime- water, when impregnated with the oxyd or solu- tion of copper, previous to the dyeing with bark, renders the colour more durable. Cotton, having been soaked two hours in a di- luted ammoniate of copper, and then hung out to dry, appeared at first of a fine blue colour, but afterwards became of a very beautiful bluish green. A bit of this cotton being dyed for a few minutes in a decoction of quercitron bark, became of a fine yellowish green : another bit dyed in the same decoction for a longer time, became of a dark brownish yellow colour; this was, however, changed to a lively yellowish green, by washing with soap, and suffered but little during three weeks exposure to sun-shine, air, and rain. Linen or cotton soaked in a diluted nitrate of lead, then in lime-water, and afterwards rinced, and dyed with quercitron bark, took a kind of nankeen brown colour, somewhat, though not very, durable. The other solutions of lead, appear to be still less useful as m dants upon cotton, for dyeing with the bark. Manganese being dissolved by a very weak or diluted sulphuric acid, and%he solution after- wards mixed with an additional portion of water, cotton was soaked therein for two hours, i70 PHILOSOPHY OF and afterwards immersed in lime water, then rinced and dyed with the bark, from which it obtained a nutmeg brown colour, inclining slightly to the olive, which proved somewhat lasting. The oxyd of arsenic is capable of serving as a mordant for the quercitron colouring matter, but as the shades produced by it may be ob- tained by cheaper and much less dangerous means, I cannot recommend its use for this purpose. Cotton, soaked in a diluted nitro muriate of gold, afterwards rinced and dyed with querci- tron bark, received a delicate olive-tinged yel- low of considerable durability ; but this mor- dant is much too expensive to be used in this, or in almost any other way. Cotton, first dipped in a weak solution of soda, became of a yellowish brown by being soaked in a diluted solution of platina by the nitro-mu- riatic acid, and being afterwards dyed with the bark, it became of an olive colour. Cotton, dipped in a weak solution of soda, and then in a diluted solution of the grey ore of cobalt, (cobaltum galena,) by the muriatic acid, became first green and then yellow ; and this being afterwards dyed with quercitron bark, the colour ♦changed to a lasting black. The pure cobalt, dissolved either by the mu- riatic or the nitric acids, and applied in this PERMANENT COLOURS. m way to cotton, produced a cinnamon brown colour, with the quercitron bark. Cotton, wetted with a solution of soda, and then with a diluted nitrate of nickle, became green, and beiu^ afterwards dyed with the bark, it became of a full cinnamon brown. Iron, though I mention it last, seems to be the most useful of the metallic bases, for dyeing on cotton and linen with the quercitron bark, and more especially for producing the drab, mud, dove, and olive colours, with the great variety of shades which result from a mixture of these upon cotton velvets, vclverets, fustians, &c. These colours have hitherto been commonly dyed from what is called the old fustic, (morns tinctoria,) though they may be given more cheaply and conveniently with the quercitron bark in the same ways, and when so given, are more lasting than those given by fustic, as I have repeatedly found by exposing samples of each to rain, sun, and air, for the space of six months together. The cheapest form in which iron can be em- ployed in this way, is that wherein it is dissolved by sulphuric acid, as in the common sulphate of iron, or green copperas ; and, after many trials, I have not found any other combinations of this metal capable of producing effects so much better in dyeing as to compensate for the in- creased expence attending their use. Copperas 172 PHILOSOPHY OF and quercitron bark, in different proportions, produce all the different shades of the drab colour, from the deepest to the lightest ; and for this purpose, the copperas may be either dissolved in a decoction of the bark, and the pieces of cotton velvet, velveret, or fustian, turned through the liquor (of a suitable heat) by the winch, or the bark may be boiled with water in one vessel, and the copperas dissolved by warm water in another, and the pieces passed as usual, first through the latter, and then through the former, and so alternately from one to the other, until the proper shade is acquired ; and by adding after the rate of one pound of chalk to eight pounds of copperas, in the vessel wherein this last is dissolved, the colour will be rendered more durable, and at the same time changed a little to the chocolate brown. To produce the olive shades, sulphate of cop- per, (blue vitriol) with about one-eighth part of its weight of chalk, or alum with a like pro- portion of chalk, may be employed along with the copperas, so as to give the drab colour a sufficient inclination towards the yellow hue; and for this purpose, the blue vitriol is, I think, preferable to alum. For the drab colours, one or two pounds of copperas, according to the fulness of colour want- ed, with about three times as much of bark as PERMANENT COLOURS. 17» of copperas, and a little chalk, will suffice to dye 1001b. weight of velvet, yelveret, or fus- tian : and for the olives, it will only be neces- sary to diminish the quantity of copperas ac- cording as the shade is wanted to incline more or less to the yellow, and add as much or a little more blue vitriol in its stead : and for this pur- pose, the blue vitriol may be either dissolved in the same vessel with the copperas, (and chalk,) or it may be dissolved with chalk in a separate (third) vessel, and the velvets or fustians, after they have been turned or worked sufficiently in the two first vessels, containing, one the copperas liquor, and the other the bark liquor, may be turned or worked in the solution of blue vitriol in the third vessel, until it inclines suffi- ciently to the yellow hue ; and, perhaps, this me- thod will generally be found most convenient to fustain dj T ers, who are frequently required at the same time to dye a great variety of diffe- rent shades. But otherwise, it probably would be most advantageous to turn and soak the pieces for a little time in the solution of copperas and chalk, or of copperas, chalk, and blue vitriol, (oralum instead of blue vitriol,) thenimmerse them for a few minutes in lime-water, and afterwards rince and dye them in a decoction of bark, by which colours much more lasting, and much less liable to spot than those commonly obtained, mio-ht be dxed: it would, however, be more 174 PHILOSOPHY OF difficult in this way to produce that great va- riety of shades, which in the other are easily attained by any dyer accustomed to the use of old fustic for the like purposes, as I well know by my own experiments, and by those of others. One pound of bark will commonly produce as much effect as four pounds of old fustic. When darker colours are wanted than can be conveniently given with the quercitron bark and copperas, a portion of Spanish sumach may be added to obtain them, as is done for saddening the colours given with old fustic and copperas; though it is possible to produce a du- rable colour, approaching very nearly to a perfect black, by the quercitron bark and the iron basis, by first soaking the cotton in a weak solution of barilla and liver of sulphur, then drying and immersing it in a diluted solution of iron, by the nitro-muriatic acid, and afterwards dyeing it with the bark. Of the Application of Quercitron Bark in Topical Dyeing, or Calico Printing. Between pages 346 and 381 of my former volume, I have given a general, though sum- mary, account of the art of calico printing, as practised during many ages by the inhabitants of India; and also of the improvements which have followed the introduction of this art into Europe. I have also particularly described the two principal mordants or bases employed to fix PERMANENT COLOURS. 1/5 and raise the different adjective colours, by topi- cal or partial dyeing ; I mean the printers' alu- minous mordant, or acetite of alumine, and what is called iron liquor (acetite of iron), made by dissolving that metal in vinegar, sour beer, &c. These mordants the calico printers have very improperly named colour,or colours, though they only afford the basis, or bases, of colour, to be afterwards obtained from madder, weld, quer- citron bark, &c. For an account of the pre- paration of acetate or sugar of lead, and of the substitutes for it, in making the aluminous mor- dant, I cannot do better than refer my readers to M. Berthollet's chapter on that subject, and to the writers therein mentioned, and, for an account of the true nature and advantage of this aluminous mordant, my readers will be pleased to recur to pages 359, 360, &c. of the former volume. Of the iron liquor, it may be pro- per to observe, that, when made with vinegar, that which has been longest kept is most esteemed. But of late much is consumed which has been prepared by dissolving iron more expeditiously in the pyro-ligneous acid, obtained by distillation from wood, and it is probable that, in some cases, the action of this acid has been strengthened by an addition of the muriatic, though this last must have a ten- dency to render the solution corrosive. Linens or cottons before they are printed, 176 PHILOSOPHY OF require to be bleached ; and the more perfectly this operation is performed either by the old or new method,* the less will the parts intended to remain white be afterwards stained by the madder, weld, or bark, liquors in dyeing ; and the more easily will any discolouration from these liquors be afterwards discharged. After bleaching, the pieces will need to be calendered, in order to produce a smooth surface, and render the woof and shoot as even and square as possi- ble, and thereby favour a due application of the mordants; which, being properly thickened by starch, flour, or gum, as formerly men- tioned, are to be applied by blocks, plates, cy- linders, &c. as those employed in this part of the business sufficiently understand. This being done, the pieces are to be well dried in a stove heat, so as to evaporate the acetous acid, which held the basis in a state of solution, and cause the latter to be more copiously deposited and fixed in the pores of the cloth. After drying, the cleansing operation follows ; and this is performed in a copper with water, nearly as warm as the hand can well bear, and a quantity of fresh cow-dung; in which the * M. Widmer, of Jouy, thinks that calicoes bleached by the oxymuriatic acid, not only become whiter, but afterwards take the different colours with better effect than when bleached by other means. PERMANENT COLOURS. 177 pieces are to be briskly worked, so as to dissolve the thickening of the mordant, or mordants, and separate all the unfixed superfluous particles of alumine, or of iron, which the cow-dung serves to entangle, and thereby hinder them from spreading and attaching themselves to the parts intended to be kept white, and there becoming the basis of a future stain, or discolouration, which it might be difficult to remove ; after this, the pieces, being thoroughly soaked and well rinced in clean water, will be fitted for dyeing with the bark.* In many cases, madder colours are mixed in the same piece with those of the bark; but in these the madder ought to be first dyed on a separate course of work, in which the mordant, or mordants, are printed only so far as the madder colours are intended to extend ; and the piece being then dried, cleansed, and dyed with the madder, and afterwards whitened by branning and bleaching, are to be calendered, and made ready to receive a second coarse of mordants for the bark, in which the pieces are to * To save time and trouble, calico printers often cleanse (if I may use this term) too many pieces of printed calico in the same deficient quantity of water, (with cow-dung) which thus becomes overloaded with the mordants, containing iron, with galls, logwood, &c. which are frequently mixed with them, and which, by combining with alumine in the parts intended to be dyed yellow, necessarily degrade the latter colour. VOL. II. N us PHILOSOPHY OF be printed, dried, cleansed, &c. as just me- tioned. My readers have been already informed, that the bark produces a good bright yellow with the aluminous mordant, and a drab colour with the iron liquor; and that both together, mixed in different proportions, produce different shades of olive and olive-brown colours. And that if a strong decoction of galls be added to the iron liquor, and the mixture applied in the same way to linen or cotton, it will, by dyeing with the bark, produce a black sufficiently fixed, though inclining a little to a brownish hue. By means, therefore, of the aluminous mordant and the ironliquor, three very distinct colours, besides the black, are obtained from quercitron bark : and, moreover, by applying the aluminous mordant upon a madder red and an indigo blue, an orange in the first case, and a green in the se- cond, will be produced when the piece comes to be dyed with the bark. I have already noticed (at page 355 of Vol. I.) the practice of colouring the solution of alum, in the East Indies, with sampfan, orsappan, (red) wood ; a practice which the calico printers of Europe have imitated, by colouring the alumi- nous mordant with Brasil wood, (and thence calling it red colour,) not only when it is intend- ed to serve as a basis for the madder red, but also for the quercitron or weld yellows ; though in the latter case, at least, the practice ought to PERMANENT COLOURS. 179 be laid aside. It is, indeed, necessary that some tinge should be given to mordants \n calico printing, in order that the printer may readily discern the exact progress and extent of his work : but it is much better to give this tinge, from quercitron bark, to figures, or parts intended afterwards to receive the bark or the weld co- lours by dyeing, than to give it from Brasil wood ; the colour of which, were it.,to remain, would hurt the true yellow intended to be afterwards fixed upon the aluminous basis: but the false' Brasil colour, not having so much affinity with the basis as to be able to maintain its situation, is always dislodged by the superior affinity of the bark or weld. This dislodgment, however, of one colouring matter by the application of another, takes up some time, and unnecessarily prolongs the dyeing process (the yellow in this case rising more slowly); and the parts intended to be kept white are also rendered liable to a greater degree of stain or discolouration. But where the mordant has been tinged with the quercitron bark, a portion of the colour intend- ed to be given is already applied to the basis ; and, though at first not perfectly fixed upon the linen or cotton, it soon becomes so in the dyeing- vessel ; whilst the additional colouring matter of the bark, having no false Brasil-wood colour to dislodge, applies itself without impediment to the aluminous basis, and produces the requisite N 2 lsu PHILOSOPHY OF degree of colour much more quickly, as may be easily seen upon a proper trial. I do not, indeed, think that any degree of tinge ought to be thus given, even from the bark, beyond what is necessary to enable the workman to sec his work with sufficient clearness ; because the particles of alumiue or of iron, when pre- viously united to any species of colouring matter, do not seem by cold application to fix them- selves either so intimately or so copiously in the fibres of linen or cotton, as they do when ap- plied without any such union or incumbrance; and I have repeatedly found, that yellow colour- ing matter, dyed upon an aluminous basis itntinged, produced a more lasting colour than it does upon a basis previously tinged even by quercitron bark, and much more lasting than where the tinge had been given with Brasil wood. And this fact will enable us to conceive one, at least, of the reasons why it is most advantage- ous, in dyeing upon linen or cotton, to apply the aluminous basis first by itself alone. But, in topical dyeing with the quercitron bark, or with weld, wherever it is necessary to give a mode- rate degree of tinge to the mordant, whether aluminous or ferruginous, (i. e. iron liquor) or a mixture of tjiese, I advise it to be given by a decoction of the bark made very strong, that it may not too much weaken the mordant, and at the same time employed as sparingly as the nature of the case will permit. PERMxVNENT COLOURS. 181 The effect of mordants topically applied, often depends greatly upon their being either too much or too little thickened with gum, starch, or flour, which are usually employed for this purpose. When the liquor has been too much thickened, it does not sufficiently penetrate the fibres or substance of the linen or cotton, and, therefore, the colour raised upon it proves weaker and less durable than it otherwise would do ; but, on the contrary, if the liquor be not suffi- ciently thickened, it runs, orspreads, too far upon the surface of the piece, and produces figures, or impressions, which prove confused and undefined. In general, the liquor for this kind of application, should be made so thick, and only so thick, as barely to prevent its spreading beyond the pro- per limits; and it seems more necessary to catch exactly this point of thickness, or fluidity, with the iron liquor than with the aluminous mor- dant, because the oxyd of iron does not com- bine so intimately as the alumine does with the acetous acid ; but, on the contrary, it remains suspended in a less divided state, and neither penetrates so freely, nor unites so intimately, as the particles of alumine with the linen or cotton to which it is applied; and, therefore, the iron liquor in particular ought never to be thickened any more than is necessary to hinder it from spreading too far. When the mordant has been applied, and 162 PHILOSOPHY OF has had sufficient time to penetrate the substance of the cloth, it should be thoroughly dried in air artificially heated, as before mentioned, so as to evaporate not only the water, but as mucb as possible of the acetous acid united to the alumine, or to the oxide of iron, in order that nothing may remain to oppose their intimate union with the fibres of the linen or cotton, which the water, and more especially the acid, necessarily would do by exerting their own par- ticular affinities upon the substances intended to be thus intimately united. It will, however, be impossible in this way to evaporate the sulphuric acid, of which the aluminous mordant, made with the usual proportions of alum and sugar of lead, alway contains a little; and which, when the pieces are brought under the cleansing ope- ration, enables the warm water to re-dissolve and separate a part of the alumine, wanted for raising and fixing the colours intended to be afterwards given by dyeing ; which alumine, being so re- dissolved and separated, is apt, even in spite of the viscidity and entanglement of the cow-dung, to fix itself again upon those parts of the linen or cotton intended to remain white, and occasion a much greater and more lasting degree of stain, or discolouration, than would otherwise take place in the dyeing vessel. These effects might, indeed, be obviated, by mixing a little lime or chalk with the cow-dung and water employed PERMANENT COLOURS. 1S3 for the cleansing, so as to neutralise the sul- phuric acid; but, by so doing, a sulphate of lime would be produced ; and this, by fixing itself on the parts intended to be kept white, would give them a calcareous basis, and occasion another kind of stain, or discolouration, almost as bad as that intended to be thus prevented. But carbonate of pot-ash or of soda used in this way instead of lime, will answer the purpose of neutralizing the sulphuric acid, without communicating any im- proper basis of colour, so as to occasion that kind of stain or discolouration which it is so de- sirable to avoid ; though if any more of it be used than what is suificient barely to neutralize the acid in question, it will exert a mischievous action, by dissolving a portion of the aluminous basis fixed upon the linen or cotton, and render the yellow, afterwards communicated by dyeing, more feeble than it otherwise would have been. A very little of the mild alkali may, however, be used in this way with advantage, so as to leave the pieces capable of receiving full strong co- lours, whilst the parts intended to remain white will be but veiy slightly discoloured by the dyeing process, and afterwards easily whitened. It is in all cases of great importance, that the cleansing operation should be well conducted, and thoroughly performed ; but more especially where a large proportion of drab, dove, and olive, colours arc to be intermixed with yellow* ; 184 PHILOSOPHY OF because the oxide of iron, which serves as a basis to the former, is very apt to attach itself too copiously to the linens and cottons on which the iron liquor is printed; and unless the redun- dant part be carefully removed in the cleansing operation, (which is a work of some difficulty,) it will remain, and be afterwards attracted and separated by the colouring matter of the bark in the dyeing vessel ; and, uniting therewith, it will give the dyeing liquor an olive or drab- colour tinge, and greatly tarnish the yellow figures, or designs, as well as stain the parts in- tended to be kept white : and, therefore, when- ever the iron liquor is to be printed upon the same piece with the aluminous mordant, the former should be diluted as much as it will bear, without making the liquor too weak to afford a sufficient basis for the colour intended to be afterwards dyed upon it. By such dilution, joined to proper care in cleansing, the yellows may be made to come out of the dyeing liquor perfectly untarnished ; which otherwise they will not do, at least when accompanied with any considerable proportion of figures, or designs, which have been printed with iron liquor. Having premised thus much concerning the operations of printing and cleansing, I now pro- ceed to that of dyeing with the quercitron bark. For this, a suitable portion of the bark, pre- viously ground, is first to be put into a dyeing PERMANENT COLOURS. 18! pan, or vessel, with cold water, and the pieces to be dyed immediately after; a small fire is then to be lighted under the pan, so as gradually to warm the water ; and, while this is doing, the pieces are to be slowly turned by the winch, in order that the colouring matter may apply itself equally : when the liquor becomes a little more than blood- warm, the colours will take suffi- ciently quick, and prove more lasting than they do when raised more hastily; because in a mode- rate warmth the colouring particles (as was be- fore observed) have time, and are enabled to ad- just themselves more accurately, and unite them- selves more closely, to the particles of alumine, than they can do when hastily thrown and ac- cumulated by a greater heat upon the printed figures or designs. And I have repeatedly found, that samples slowly dyed with the bark in this way, being exposed to the sun and air along with others dyed more expeditiously in a boiling heat, proved much the most lasting. And if the quercitron yellow has at any time been found less durable than that of the weld,* it can only * Berthollet, in the last edition of his Elements, &c. has ap- propriated a chapter exclusively to the quercitron bark ; which he begins with the following observation : " C'est a Bancroft que V on doit l'acquisition de cette substance tinctoriale : il a donne une ample description de ses proprietes et des usages aux- quels elle est propre : nous allons en presenter le sommaire j" &c. and after having done this, he adds "on doit indubitablement 186 PHILOSOPHY OF have been so, through some defect in the mode of dyeing, at least if there was none in the mor- dant. Hitherto the bark has generally been used with too much heat at first. I say atjirst, because after the colour has been slowly raised, by liquor moderately warm, to nearly the proper height, a boiling heat will do no harm, excepting that of occasioning a little more stain or dis- colouration upon the parts intended to remain white; and though the avoiding of this is an additional motive for applying the bark in water of a moderate warmth only ; yet this of it itself might not be a very powerful motive, because such stains from the bark are much more easily removed than those resulting from weld. But the most essential difference between these vege- tables, respects the degree of heat by which their several colours are most permanently fixed upon linen or cotton ; that of weld requiring regarder le quercitron comme une substance tres utile en tein- lure ;" but after thus bearing testimony to its utility, he inti- mates a belief, that the colour which it affords is not so lasting as that of weld. But if there should be, as has some- times appeared probable, some little foundation for such a belief, the difference is much more than compensated by the great advantage which the quercitron bark possesses of producing no discolouration to the grounds, or parts intended to remain white, sufficient to require a similar exposure on the grass by which the weld yellows always suffer, and are often greatly in- jured, particularly in winter, when the bleaching process is often necessarily continued several months. PERMANENT COLOURS. is: at least a scalding, if not a boiling, heat to render it lasting, whilst the bark colour, as has been already observed, proves most durable when applied in water but little more than blood- warm. And, indeed, I have found, during the summer months, that cottons printed with the aluminous mordant were able to imbibe a good, though not a very high, yellow, by only remain- ing a few hours with bark in water of the heat of the open air, (in which it was placed,) and without any considerable stain or discolouration upon the parts not printed. A piece of the calico so dyed in the heat of the atmosphere only, be- ing cut off and further dyed with the bark in boiling water, it imbibed a greater body of colour ; but a sample of this, and of the former or paler yellow, being equally exposed to the sun and air, I found at the end of three weeks, that the latter, which had been the deepest, retained no more body than the other ; the additional co- louring matter, which in a boiling heat had been enabled to apply itself upon the aluminous basis, having been all discharged during this exposure to the weather. A fact which seems to indicate, that when the alumine has attracted to itself a certain portion of colouring matter, any addi- tion made to it afterwards by the aid of heat, will be less permanently fixed, and, therefore, lia- ble to be more speedily removed by any of the 1SS PHILOSOPHY OF I causes which usually contribute to the decay of colours. All the different shades of yellow may be ob- tained from the quercitron bark by varying the quantity, and applying it with greater or lesser degrees of heat during a longer or shorter time. By using the bark sparingly in water only blood- warm, pale delicate yellows may be raised in about fifteen or twenty minutes, and the parts intended to be kept white will receive scarcely any discolouration j by a larger proportion of bark, and by keeping the pieces for a longer time in the dyeing liquor, though without increas- ing its heat, a full and clear lively yellow may be produced ; and by a still greater proportion of the bark, and a prolongation of the dyeing ope- ration in a scalding heat during the latter part of it, the colourmay be raised, first to a high golden, and afterwards to a very full brownish yellow. The quantity, therefore, of bark to be employed, must always depend upon the nature and close- ness of the figures and impressions which are to be dyed, and the heigh l or fulness of colours in- tended to be produced. Commonly, however, one or two pounds of bark will suffice for each piece; but, where too little has been employed at first, a farther quantity may be afterwards added without inconvenience; and, when the dye- ing is to be performed in a very moderate heat, it will always be most advantageous to employ a PERMANENT COLOURS. 16S little more bark than is necessary ; which may be clone without any loss of colouring matter, because other pieces may be afterwards dyed, with a farther supply of bark, in the same liquor; and I have found that yellows, ljrhether dyed from bark or weld, commonly prove most durable when the dyeing liquor has been some- what plentifully stored with colouring matter ; and, in general, I think it best to employ the bark so freely, as that theliquormay bestrongenough, without being made more than blood-warm, to produce full bright yellows in the space of half or three quarters of an hour; the tinge, ordiscolour- ation, which the parts not printed imbibe from the bark in this way not being half so great as that produced by weld, and it being afterwards discharged with less than half the time and trou- ble which even an equal degree of stain from the latter would require. Indeed, where the pieces have been at first well cleansed from all loosely adhering and superfluous particles of the alumi- nous or ferruginous bases, the discolouration from bark generally proves so inconsiderable, that by rincing, or washing, them in cold, and more es- pecially in warm water, it may be sufficiently re- moved without either branning or bleaching, ex- cepting where the un printed parts are required to be uncommonly clear and white : and when this is the case, I think it best to add after the rate of one pound of cream of tartar, in powder, for every twelve or fourteen pounds of bark, put- >90 PHILOSOPHY OF ting the tartar into the water immediate!} 7 after the bark, and then dyeing the pieces, as I have already explained. The tartar used in this way vvill contribute much towards keeping the white or imprinted parts free from stain or discolour- ation ; and it will, moreover, give the querci- tron yellow that bright, clean, and delicately greenish hue which is sought for in the weld, so as to make the former resemble the latter. But, as the tartar tends to keep the quercitron yellow from taking so fast, or rising so high, as it would otherwise do, the liquor may, in this case, be made hotter in the latter part of the operation. On the contrary, if, instead of tartar, one pound of clean white pot-ash be added for every thirty pounds of bark, a very high, and, at the same time, a very bright yellow will take so quickly, that the liquor should never be more than blood-warm : and, though the imprinted parts may seem a little more stained than they are when no potash is used, the stain will be dis- charged by thoroughly rincing and washing the pieces as usual. Some calico printers, not acquainted with the bestmethodsof employing thebark, havethought proper to join with it a little of the decoction of weld :* I cannot, however, recommend this prac- tice, because, in truth, the bark, when properly used, wants no such assistance, and because the * This practice seems no longer to exist. PERMANENT COLOURS. 191 colouring matter of the weld does not take per- manently without a greater degree of heat than ought to be employed with the bark. It more- over occasions a much greater stain upon the un- printcd parts, and at the same time degrades the madder reds and purples, (where these colours have been previously dyed,) much more than the bark. It is to be observed, that the very moderate warmth, which bestsuits this kind of dyeing with the bark, does not, in general, completely ex- tract its colouring matter, at least from such parts thereof as are not finely ground ; but, being tied up in a bag, it may be afterwards boiled separately in water, and the decoction so made may be employed for dyeing olive and drab co- lours, where they are not intermixed with yel- lows or reds. Some calico printers have, in- deed, thought it best, in all cases, to begin by boiling the bark in a small quantity of water, so as fully to extract the colouring matter, and then, for yellow, as well as drab and other bark colours, to put a suitable proportion of the de- coction into the dyeing vessel, with clean warm water, and dye the pieces therein, adding more of the decoction as wanted from time to time. I do not, however, think this practice so conve- nient as that which I have recommended. A very ingenious printer in a distant country, and warm climate, sometime since, favoured me 192 PHILOSOPHY OF with an account of his method of using the bark, which he considers as one of the best : u I pound (says he) the bark, and boil it in a good quan- tity of water, say twenty-five gallons to seven pounds of bark ; after which I let it settle, and pour off the clean decoction ; of which I acid a portion to a tub full of clean cold water, and im- mediately, with the hand, pass a quantity of clean rinced (printed) cloths through the water ; they take on colour very quickly, and it appears fresh and beautiful : I then add another portion of the decoction, and bring out a pretty full yel- low ; meanwhile I have my large copper ready with clean water as warm as the hand can well bear, and to this I add also a portion of the de- coction ; and then remove the cloths from the tub into the copper, and turn them quickly round; by which method 1 obtain the best and most du- rable yellows : ten or fifteei* minutes will be long enough to keep the cloths in warm water, where a delicate yellow is required." " I found it easy," continues the writer. " to manage the olive and drab colours in the copper ; for these, I use the bark which has been once boiled for the yellow ; seven or eight pounds of it are to be boiled in twenty-five gallons of water, and then the whole is to be thrown into a copper containing about 250 gallons ; through which I pass about 225 yards of cloth perfectly well rinced, or, if it be heavy work, only about 180 yards, which are PERMANENT COLOURS. 193 to be turned quickly round : I begin with a mo- derate fire, which, in half an hour, is to be raised so as to make the water almost boil. Here, and especially for dove colours, I use a little sumach, which requires considerable heat before it pro- duces any good effect ; and, therefore, I think it useless for yellow, which the bark produces with so little heat. 1 have seldom allowed more than an hour for such olives, drabs, and doves ; and I never join yellows with them, because the grounds will in this wavbe so much stained as to require more bleaching than the yellows can bear without injury ; but doves, olives, and drabs, stand the bleaching, and remain unimpaired after the grounds are become perfectly white." This account the writer concludes by saying, " I have been able to do more variety of work with the bark than with any other colouring matter yet known ; it is pleasing to work with, as it takes effect quickly, and is very easily managed by any person who knows the business of neutra- lizing salts, and preparing cloth to receive co- lour." The rule which this gentleman seems to have prescribed to himself, of never joining the drab and dove colours to the yellow, is, I believe, much too rigid ; for though, in truth, it is im- possible to dye perfectly bright yellows where they are intermixed with any considerable pro- portion of what is called the black colour, and vol. ii. o 194 PHILOSOPHY OF difficult to do it where the drab and clove co- lours abound very much ; yet, in the latter case, this difficulty may be very much diminished by using the iron liquor of no greater strength than is necessary, and taking care to have the pieces thoroughly cleansed (as lately mentioned) be- fore they are put into the dyeing vessel : if this be done, a considerable portion of olive, drab, and dove colours may be intermixed, and even a lit- tle of the black, without any material degrada^ tion of the yellow. To improve the black, and darken the drab or dove colours, (which the printer is often desirous of doing,) a little Ma- laga sumach, (rhus coriara,) in powder, may be advantageously employed with the bark, after the rate of o ne pound of the former to three or four of the latter. It is, 1 believe, generally thought best to raise the colours first with the bark, and afterwards change, or darken, the doves and blacks by adding the sumach, and continu- ing the process until the desired effects have been produced. My own experiments, however, lead me to conclude, that time may be saved, and every good purpose attained, with equal certain- ty, by putting the sumach into the dyeing vessel along with the bark, and thus applying the co- louring matters of both at the same time ; taking care, however, not to heat the dyeing liquor be- yond what the hand can bear. In this way the parts imprinted may be kept perfectly white, so as PERMANENT COLOURS. 195 never to need either bleaching or branning. The sumach, indeed, when put into the water at the same time with the bark, and used in this way, produces, in an extraordinary degree, the effect of keeping the white or imprinted parts perfectly clear and free from all discolouration ; which it probably does by means of a particular acid, contained in this and many other astringent ve- getables : one pound of sumach to three of the bark will be amply sufficient for this last purpose; and in that proportion the sumach will make the parts printed with iron liquor incline towards a purple colour instead of the drab, which quer- citron bark used alone would produce. This change of colour produced by sumach will sometimes render the use of it inconvenient ; but when this is not the case, a small proportion thereof joined to the bark, as before mentioned, will- prove more effectual than cream of tartar in preventing even the slightest stain or disco- louration upon the imprinted parts of cottons to- pically dyed. A gentleman, of whose information I have more than once availed myself, some time since brought from Bengal, and gave me, a parcel of the dried leaves and tops of a plant there called lyiioicah, and employed, as he informed me, in the dyeing of topical or field colours, by put- ting a small quantity of it into the copper when the colours begin to rise, in order to keep the o 2 196 PHILOSOPHY OF grounds or imprinted parts clear ; an effect which* upon trial, I found it produce nearly as well as sumach ; and upon dyeing abitof cotton, which had been printed with iron liquor and the alumi- nous mordant, separately, in a decoction of this plant only, it imbibed colours very nearly resem- bling those of sumach, though the decoction itself, even when made very strong, did not discover any astringency to the taste. The berries of the common Pennsylvanian sumach (rhus glahrum) are covered with a red farinaceous matter, containing a large proportion of an acid, which appears to resemble that of tartar. These berries employed with the quer- citron bark, after the rate of one pound of the former to twelve of the latter, produced effects nearly similar to those of cream of tartar, as already mentioned, iu preserving the imprinted parts of cottons from being stained, and in giving the quercitron yellow the pale greenish complexion which distinguishes that of weld. Such means cannot, however, be employed where very full high yellows are wanted ; and when this is the case, if the grounds or imprint- ed parts are required to be perfectly clear and white, it may be best to employ a little clean soda in the dyeing, as lately mentioned, and afterwards to spread the pieces for a day or two upon the grass, laying what is called the wrong side upwards, as is practised with other field co- lours. Those of madder and weld, indeed, always PERMANENT COLOURS. 197 require this operation, though it cannot be wanted for those of the bark, except in the single case just mentioned ; and then only for a very short time, unless it be in rainy or cloudy weather, when thiskind of bleaching proceeds very slowly with all colours, because the action of the air is then not only unassisted by the rays of the sun, but obstructed by the water which it holds in a state of solution, Messrs. T. H: and son, very ingenious dyers of printed velverets, fustians, &c. near Man- chester, some time since informed me of their having purchased the knowledge of an advanta- geous method of using the bark for this particu- lar kind of dyeing, and of their having practised it with so much success as to have wholly laid aside the. use of weld. This method they after- wards gave me an account of, in consequence of my offering to repay what it had cost them; which I did, from a desire to afford the public all possi- ble information on this subject. Their account is as follows, viz. " In using the quercitron bark, for every four pieces of half-ell velverets, about forty yards long, we take eight pounds of the light- coloured bark, and put it into a cask large enough to hold about 70 gallons, open at the top, and provided with a spigot and faucet, placed about six inches from the bottom, to draw off the liquor : we fill this cask with boiling water, stir it well, and let it remain upon the bark for three 198 PHILOSOPHY OF hours or more ; and then after the (printed) i^oods have been well washed out of the dveingf liquor, for the four pieces we put four pounds of Malaga sumach into a copper nearly filled with water, and with a very little fire under it ; in this we put and keep the goods for about one hour, during which the dove or drab colours may be rendered sufficiently dark by keeping the liquor, at most, a little more than blood-warm. When the goods are taken out of the sumach liquor, they must be rinced in water; and whilst this is doing, we draw the clear bark liquor out of the cask, and put it into a copper with as mucli water as will serve todye the goods conveniently; we then light a fire, and gradually bring the liquor to a blood warmth in about an hour, keeping the goods therein till the yellow becomes sufficiently dark or full, and taking care that the liquor be not made too hot. The goods, being well washed after dyeing in this way, will be found white without branning." It ought to be remembered, that according to this method, the sumach is to be applied separately before the bark, instead of being- applied after or along with it, as I have just recommended in calico printing. How far this method may he preferable to the other for the dyeing of printed velverets, future experi- ence must determine ; though, certainly, that of Messrs. II. and son ought, on this PERMANENT COLOURS. ltt> point, to have great weight, even at present. In calico printing, however, this method of ap- plying the sumach and bark has been tried, not only by the experiments which I have made upon a small scale, but by those which an in- genious calico printer made sometime since on a larger one, at my desire, and in both, without affording any reason to prefer it over the other.* It can hardly be necessary for me to mention * Some years after the preceding parts of this chapter were first published, and in consequence of M. Seguin's discovery, respecting the tanning principle in vegetables, it occurred to me "to try the effect of gelatine, glue, or animal jelly, in separat- ing and precipitating that principle, of which a large pro- portion notoriously existed in this, as well as other oak barks ; and with this view I added a little of a solution of the whitest glue among that commonly sold, to the water, in which I dyed bits of calico, that had been impregnated with the alu- minous and ferruginous mordants, and I have found, as I had, in some degree expected, that by this separation ?nd precipita- tion of tanning, the yellow then dyed, was rendered more delicately clean and pure than it would otherwise have been, and that the slight discolouration of the white grounds, com- monly observed, was, if not completely obviated, at least much diminished : since that time this use of glue has become general among the calico printers, and with so much benefit, in securing both the yellows and the white grounds, from the dis- colouration which, though slight, had before commonly re- sulted from the presence of the tanning principle, that the use of weld in calico printing, has, as lam informed, leen entirely laid aside for that of the quercitron lark, at least in this king- dom. 200 PHILOSOPHY OF here, that the quercitron yellow produces a green upon an indigo blue, and an orange upon the madder red, in the same ways, and by the same means, which enable the weld to produce these colours in calico printing. Nor need I The following method of employing glue and sumach with quercitron bark, is extracted from a letter written by one calico printer to another. ** For dyeing the pieces, after they have been well cleansed, I recommend two pounds of the best glue, eight pounds of su- mach, andeight pounds of bark, well ground, to be put together into a copper over night, if convenient ; these quantities wil! sufficient for six of your heavy pieces. When the copper is made a little warm, the glue, if stirred, will soon disperse itself through the water, and produce its effect upon the colouring matters, and the parts which have been printed with the mordants, will speedily attract the dye; so that by pro- per management the grounds may be made perfectly white, only by washing the pieces when they come out of the cop- per ; though you may pass them through hot water, if you think it necessary. When you have blacks and drabs to follow your yellows, the above proportions will be best ; though they may be varied according to the nature of your work j e. g. you may employ to ten pounds of bark, to six or eight sumach. In all cases you may ground in the yellow on the table with the drabs, which will do away one fourth of the grounding, and you may bring all your yellows out of the copper, without any stain upon the grounds. Chintz work will not tinge the lay work ; and this will be the case with olive and chocolate colours j and as they never need branning, or bleaching, the colours will not be impoverished by these operations ; and the whole process may be finished in less time than is re« quired merely to boil the weld." \ PERMANENT COLOURS. 201 mention the advantage which the bark possesses over weld in this way, by not tarnishing the madder colours upon pieces where such colours have been previously dyed ; this advantage be- ing now generally known and acknowledged. Of the Uses of Quercitron Bark, in producing Topical Yellow and other Colours i prosubstan- tively, upon Cotton and Linen. By the denomination of prosubstantive topical colours, I mean certain mixtures, in which the colouring matter and the mordant or basis are combined in a fluid state, fit to be applied to- gether by the pencil, block, Sec. to linen or cot- ton, as explained at page 358 of volume I ; these are what calico printers have usually named chemical colours ; an appellation too vague to be retained in a work which aims at precision and systematical arrangement. Were it possible to obtain a sufficient number of lasting and bright colours of this kind, at a moderate expence, the art of calico printing might be practised with but little trouble, and would soon reach the highest degree of perfec- tion. Whether so many of these ever will be discovered, as to render topical dyeing unneces- sary, I know not ; but if we cannot obtain all that is desirable in this respect, the art will, at least, derive benefit from any improvement in the few prosubstantive topical colours now in '202 PHILOSOPHY OF use ; and more especially from any addition to their number. My readers already know that alumine, or the earth of alum, when dissolved, especially in the acetous acid, and conveyed into the pores of linen or cotton, is able afterwards to attract to itself different adjective colouring matters, ap- plied either by general or by topical dyeing, so as to produce lasting red, yellow, and other co- lours ; and it is much to be regretted that, for reasons which I have endeavoured to explain in other parts of this volume, the same mordant will not produce colours equally permanent, when it has been previously mixed with the co- louring matter, and is afterwards applied (with it) topically to linen or cotton. The difference in this respect, is, indeed, very great among the madder colours ; those dyed upon an aluminous basis, applied separately, being always very durable, whilst those given by prosubstantive topical application, (the colouring matter and mordant being first united) fade and decay very speedily. The difference is, however, so much less when colours are produced in these different ways from quercitron bark instead of madder, that I can with confidence recommend the bark, as affording better and more durable prosub- stantive yellows for topical application, than any thing else yet discovered. The most sim- ple yellow of this kind which I have to offer, PERMANENT COLOURS, 203 may be prepared in the following way and pro- portions, viz. For three gallons of prosubstan- tivc tingent liquor, let three pounds of alum, and three ounces of clean chalk be first dissol- ved in a gallon of hot water, and then add two pounds of sugar of lead ; stir this mixture oc- casionally during the space of twenty-four or thirty-six hours, then let it remain twelve hours at rest, and afterwards decant and preserve the clear liquor ; this being done, pour so much more warm water upon the remaining sediment, as, after stirring and leaving the mixture to settle, will afford clear liquor enough to make, when mixed with the former, three quarts of this aluminous mordant, or acetite of alumine. Then take not less than six, nor more than eight, pounds of quercitron bark, properly ground, put this into a tinned copper vessel, with four or live gallons of clean soft water, and make it boil for the space of one hour at least, adding a little more water, if at anytime the quantity of liquor should not be sufficient to cover the surface of the bark : the liquor having boiled sufficiently should be taken from the fire, and left undisturbed for half an hour, and then the clear decoction should be poured off through a fine sieve or canvas strainer. This being done, let six quarts more of clear water be poured upon the same bark, and made to boil ten or fifteen minutes, both having been 204 PHILOSOPHY OF first well stirred ; and being afterwards left a sufficient time to settle, the clean decoction may then be strained off, and put with the former into a shallow wide vessel to be evapo- rated by boiling, until what remains, being- joined to the three quarts of aluminous mordant before mentioned, and to a sufficient quantity of gum or paste for thickening, will barely suffice to make three gallons of liquor in the whole. It will be proper, however, not to add the aluminous mordant until the decoction is so far cooled, as to be but little more than blood- warm, and these, being thoroughly mixed by stirring, may afterwards be thickened by the gum of Senegal, or by gum Arabic, if the mixture is intended for penciling ; or by a paste made with starch or flour, if it be intended for printing. Where gum is employed, it will be proper first to dissolve it in water, using only what is barely sufficient to produce a solution, lest a greater quantity of water should increase the mixture beyond the quantity of three gallons, for which the portions of bark and aluminous mordant here prescribed, will properly suffice, but not for more, without weakening the colour in some degree ; and for this reason, it may be safest to evaporate the decoction rather more than seems necessary ; because, when mixed with the other ingredients, if the whole proves PERMANENT COLOURS. 205 to be less than three gallons, the deficiency may be readily supplied by a little warm water. In preparing this mixture, however, great care must be taken to thicken it only so much as may be necessary to keep it from running or spreading beyond the proper limits; since every degree of thickening, beyond this point, will hinder the colouring matter from penetrat- ing sufficiently into the fibres of the linen or cotton, and thereby render the colour superficial and feeble. When this prosubstantive mixture, (which I shall distinguish as No. 1,) after being duly prepared, has been applied to linen or cot- ton by the pencil, or otherwise, the pieces should he thoroughly dried by a stove heat, then soaked in lime-water, and afterwards streamed or placed in clean running water, to remove the superfluous colour; and if running water be wanting, other water should be copiously em- ployed for this purpose, thickened with chalk and cow-dung. A good lively yellow may be produced in this way, not indeed quite so lasting as that obtained when the mordant alone is applied first, and the colouring matter afterwards, by topical dyeing ; it will, however, be able to bear the action of sun and air, and also of soap in washing, for so long a time, as almost to deserve the appellation of a fast colour. 206 PHILOSOPHY OF It must, however, be observed, that this yel- low, though nearly, or quite as high as that given by topical dyeing with either weld or quer- citron bark, docs not prove so high and full as is desirable for this mode of application ; since colours which are applied by the pencil bear but a small proportion to the others with which they are intermixed, and are, therefore, required to be more strikingly full, that they may not be over- looked ; and it is only in this respect that the co- lour obtained from French berries, (Rhamnus in- fectorius) and called the berry yellow, has given any degree of satisfaction, it being of all others the most fugitive and fallacious. To relieve calico printers from all temptation to use a colour, which, being-fitted only to deceive, ought never to have been used, 1 have made frequent trials with the quercitron bark, joined to almost every pos- sible mordant or basis ; and of these, some have been attended with success, though the mean* employed in several of them, are either too ex- pensive or too difficult of application for general use, by persons not versed in chemical operations. There are others, however, not liable to these objections ; and, perhaps, all things considered, the most convenient among the several means of raising the quercitron yellow for prosubstan- tive topical application, and, at the same time, of increasing its durability, may be found in the nitrate of copper, and the nitrate of lime, PERMANENT COLOURS. 20JT added to the mixture, No. 1, just described.* It is, indeed, true, that some of the solutions of tin produce still higher yellows with the quercitron bark; but they are liable to at least two objec- tions, which will be particularly mentioned hereafter. If copper, in small pieces, be put by a little at a time, into a large open glass vessel, partly filled with single aqua fords, until the acid can dissolve no more of the metal ; and if the solu- tion be left open to a free access of air, it will soon be wholly converted into blue crystals, which are, what I mean at present, by the deno- mination of nitrate of copper. About one pound and a quarter of this salt may be added to the three gallons of prosubstanti ve yellow, No. 1, together with four ounces of pure unslacked lime, previously mixed with eight ounces of single aquafortis. Clean oyster-shells, or marble tho- roughly burnt, will afford the best lime for this purpose; which should he beaten into powder befbre it is put into the aqua fortis, to form the nitrate of lime here wanted. This, as well as the nitrate of copper, should be added to the * A very cheap and useful composition of this kind may be made, by dissolving, in a strong decoction of the quercitron bark, a mixture of powdered alum, with half its weight of sulphate of copper, and one eighth of its weight of carbonate of soda — and afterward thickening the solution by gfuiij &:c. as usual. 203 PHILOSOPHY OF decoction of bark, before-mentioned, soon after the aluminous mordant, and before the liquor has been thickened, by gum or paste; and the mixture should afterwards be well stirred, and kept a little more than blood- warm for half an hour before the thickening is added. The nitrates of copper and of lime, joined in this way to the mixture of No. 1, will conside- rably raise the yellow colour, and also enable it, for a longer time, to withstand the action of sun and air ; they will also enable the colour to bear the action of vinegar and weak acids a little better than it otherwise would, though I do not consider this last as any test of the goodness of a colour, nor as being a circum- stance of any great importance. This prosub- stantive colour I shall distinguish as No. 2 ; and, considering that the bark in this way affords a colour full as high, and infinitely more lasting, as well as cheaper, than any which can be obtained from French berries, I think those calico printers, if there should be any, who may hereafter continue to employ the latter, will shew themselves strangely unmindful of their own interest, as well as of their duty to the public, and the credit of their art. The nitrate of al Limine, employed as a mor- dant with the decoction of bark, produces a prosubstantive topical yellow of considerable durability ; but it is apt to acquire too much of a brownish complexion. PERMANENT COLOURS. 209 The muriate of alumine, mixed with the de- coction of bark, produces in this way, effects very similar to those of common alum ; and this is also the case where a tartrite of alumine is employed. Alumine dissolved in the pyro-lig- neous acid, being tried with the bark in this way, produced effects perhaps a little, though but a very little, better. None of the solutions of alumine by potash, soda, or ammonia, succeeded as mordants with the bark, for topical application, so well as the solutions made by acids. If a decoction be made from six or eio-ht O pounds of bark, as directed for the preparation No. 1, but without any of the aluminous mor- dant, and if two pounds of the nitrate of cop- per, lately described, be dissolved therein whilst a little warm, and the mixture afterwards pro- perly thickened, it will produce, when applied to linen or cotton, a good prosubstantive yd' lowish green, capable of bearing exposure to sun and air, and wishing with soap, so as almost to deserve the name of a last colour. By adding four ounces of lime, mixed with eight ounces of aqua fortis, the colour will be improved; and it may be rendered still more beautiful, and, I think, a little more lasting, by adding immediately after the nitrate of copper, one pound of ammoniate of copper, made by pouring a pound of the liquor ammonia?, of the London VOL. II. p 210 PHILOSOPHY OF Dispensatory, into a close glass vessel, with a Sufficient quantity of filings, or small bits, of copper, and keeping the vessel closely stopped, until the alkali has combined with as much cppper as it can dissolve, and thus acquired a very beautiful deep blue colour. This yellow- ish green prosubstantive mixture I shall dis- tinguish as No. 3 ; and, I believe, there are no other means by which a similar colour can be obtained of equal beauty and durability. The ammoniate of copper alone produces, with the decoction of bark in this way, a green- ish yellow deserving of notice. The acetite of copper (verdigrise dissolved by vinegar) mixed with a decoction of the bark, and topically applied upon cotton, produces a full brownish yellow, which, however, proves not so lasting as either No. 1, or No. 2. And the muriate of copper, with the decoc- tion of bark, produces in this way a yellowish olive, which soon fades upon linen and cotton. It has already been noticed, that cottons impregnated with the oxides or solutions of tin as a basis of colour, and then dyed with quer- citron bark, imbibed colours highly beautiful, and capable of resisting the action of boiling soap-suds, as well as of strong acids ; but, at the same time, fugitive when exposed to the sun and open air, a defect which it would have been reasonable to expect, even in a greater PERMANENT COLOURS. 211 degree, where the tin basis, instead of being previously fixed in the cotton, was first united to the colouring matter, and afterwards applied therewith prosubstantively. A contrary effect, however, really takes place, in some degree, because the oxide of tin has greater affinity to the fibres of cotton, after a previous combina- tion with the colouring matter, than it has sepa- rately. If a decoction be made from six pounds of bark, as for the preparation, No. 1, (but without any aluminous mordant), and one pound, or one pound and a quarter, of the murio-sulphate of tin, so often mentioned, be added, the mixture being afterwards well stirred, and properly thickened, will afford a very bright and full pro- substantive yellow, liable, indeed, to become a little brown 1 * by exposure to the sun and air ; but, at the same time, of considerable durability, and able to withstand the action of acids or boiling soap-suds. It must, however, be re- membered, that the oxide of tin has a stronger attraction than that of iron, for most vegetable colouring matters, and especially for that of madder ; and, therefore, when prosubstantive colouring mixtures, containing solutions of tin, like that just mentioned, are applied clostly upon madder purples, or blacks, (made such by the oxide of iron) these latter colours will become red wherever thev are touched by these mix- p 2 212 PHILOSOPHY OF tures. And for this reason, whenever a pro- substantive yellow is wanted to be laid imme- diately upon the edge of a dark madder colour, (which is most frequently the case) it will be proper to employ the preparation, No. 2. The nitro-muriate of tin, made with about two parts of nitric to one of muriatic acid, pro- duces, in this way, with the decoction of bark, a very high lively yellow, capable of resisting strong acids, boiling soap, &c. but. very liable to become brown by exposure to the sun and air; an effect which I found lemon juice had the power of preventing, in spots, which, for ano- ther purpose, had been wetted therewith. Olive oil, applied so as to cover yellow spots or figures produced by the decoction of bark and nitro- muriate of tin, appeared to have no effect in defending or preserving the colour from injury by exposure to the sun and air ; and linseed oil, applied in the same way, did manifest harm, the spots covered by it having acquired a blackish hue after a lew weeks exposure to the weather. These, joined to other facts, may hereafter help us to some useful conclusions. Muriate of tin, with the decoction of bark, applied prosubstan- tively to cotton, affords a very lively delicate yellow ; but it is less capable than the former of resisting the action of soap and of acids ; nor does it long bear exposure to sun and air. This is also true of the yellow produced in PERMANENT COLOURS. 21S this way by the tartrite of tin and decoction of bark The sulphate of tin, mixed with a decoction of the bark, and applied in this way to cotton, gives a kind of cinnamon colour sufficiently lasting. Phosphate of tin produced only a dull brownish yellow with the decoction of bark. Tin, dis- solved by cream of tartar, mixed with twice its weight of muriatic acid, produced, with a decoc- tion of the bark, prosubstantively upon cotton, a very lively strong yellow, of considerable durability. I have tried many other solutions and combinations of tin with the bark, and, indeed, almost every one which it is possible to form, but without any effects better than those which may be obtained from the mixtures already mentioned. My readers, therefore, will not require a particular account of them, espe- cially as the use of all prosubstantive yellows which contain solutions of tin, though they afford by much the highest and most beautiful colours, must prove very limited, by reason of their effect of reddening the dark madder co- lours. It has been already observed, that the decoc- tion of bark with the nitrates of copper and lime, and the ammoniate of copper, produces a good prosubstantive yellowish green ; and this may be rendered darker and fuller by super- adding a portionof the logwood blue. Two calico 214 PHILOSOPHY OF printers have assured me, that by combining the bark and logwood with particular solutions or preparations of copper, they had been able to obtain a green, for topical application, so fast as to bear the process of field bleaching without injury ; and one of them declared, that it was by adding to a decoction of bark and logwood, boiled together, a suitable portion of sulphate of copper and of verdigrise, with a little potash ; this last, and the effervescence which is produced, he seemed to think of importance. As yet, how- ever, my endeavours to produce a green fully answering this description have not succeeded, though they have several times been attended with such appearances of success, as will induce me to make farther trials. Those hitherto made seemed to have failed principally by the want of sufficient permanency in the blue or logwood part of the green colour. A great number of experiments, made at least seventeen years ago, taught me, that a beautiful prosubstantive blue, capable of resisting sun and air for a considerable time, when applied topically upon linen or cot- ton, might be obtained by combining the colour- ing matter of logwood With the sulphate of cop- per and the ammoniate of copper; a fact which I communicated to several calico printers, who have acknowledged its beneficial effects. Six pounds of logwood boiled with water, as directed for the quercitron bark, will afford co- PERMANENT COLOURS. 215 louring matter enough for three gallons of liquor when thickened; to this decoction, whilst warm and before it is thickened, two pounds of blue vitrol may be added, and as soon as it is dissolved, two pounds of ammoniate of copper, made as already explained, and the liquor, after being well stirred, may be thickened and applied as usual. By substituting the nitrate of copper for the sulphate of that metal, a dark blue may be produced, equally durable, but not so lively and beautiful ; though I think this last rather prefer- able to the other, for the purpose of forming a prosubstantive green with the quercitron yellow; for which purpose it will be sufficient to mix as much of this logwood blue with the yellowish green, No. 3, as may serve to produce the parti- cular shade of colour wanted ; or the logwood blue may be added to the yellow, No. 2, for the like purpose. And though the greens produced in these ways are not so lasting as to deserve to be called fast colours, they are as good as any which I have yet been able to produce by unit- ing the quercitron and logwood colouring mat- ters, and, indeed, are such as it may be often con- venient to employ. If a suitable portion of strong iron liquor be mixed with a decoction of the quercitron bark, made as already directed, and the mixture be properly thickened, a prosubstantive drab colour of some durability for topical application, may 216 PHILOSOPHY OF be produced ; and this mixed with an equal por- tion of the preparations, No. 1, or No. % will produce an olive. If a solution of iron, by a diluted muriatic acid, or by a diluted nitric acid, be employed for this purpose instead of iron liquor, it will produce colours a little more lasting ; but these solutions should be employed sparingly, that they may not hurt the texture of the linen or cotton to which they are intended to be applied. Zinc, dissolved by the sulphuric, the nitric, and the muriatic acids, separately, and mixed with the decoction of bark, produces brownish yellow colours of different shades, but none of them sufficiently lasting when topically applied upon linen or cotton. Mercury, dissolved by the different acids, pro- duced with the decoctions of the bark different brown and yellowish brown colours, but none of them more durable in this way, than those afforded by different solutions of zinc. The nitro-muriate of platina, mixed with a suitable portion of decoction of bark, and topi- cally applied either to linen or cotton, produces strong full-bodied snuff colours, which bear the action of acids and of the sun and air. The nitrate of silver, mixed with a decoction of the bark, produces, by topical application upon linen or cotton, strong dark brown and cinna- mon colours of considerable durability. PERMANENT COLOURS. 217 The nitrate of lead, with the colouring mat- ter of bark, produces in this way a drab colour of equal durability. The nitrate of bismuth, with a decoction of the bark, produces a very full and strong brown- ish yellow, which would prove lasting, were it not liable to become almost black by alkaline sulphures, by sulphurated hydrogenous gas, and sometimes by the action evert of common soap. The muriate of bismuth produces a drab colour with the bark, and the sulphate of that metal a yellow ; but neither of these are lasting upon linen or cotton. The nitro-muriate of antimony produces with the bark, a kind of snuff colour of some dura- bility on linen and cotton ; and different shades of brown were produced in this way by the nitrate and the muriate of cobalt with the bark, which, however, soon faded by exposure to suu and air. In giving this account of the properties and uses of quercitron bark, I have had before me notes of several thousands of experiments made therewith, in almost all possible ways, and with almost all possible chemical agents. But as a detail of their effects would more than exhaust the patience of any reader, 1 shall content my- self with stating, as I have here done, the results of those which seem most likely to prove use- ful ; and, probably, what I have already stated is more than enough on this subject. I have, 218 PHILOSOPHY OF however, thought it incumbent on me to omit nothing in any degree likely to afford useful information respecting a new dyeing drug, first brought into use by my exertions, and which, without them, would, probably,, have remained unknown as a dyeing drug for ages to come :— a drug which has already produced important benefits, especially to the art of calico-printing in Great Britain ; and is likely hereafter to benefit other European nations, as well as the United States of America, in an eminent degree. The consumption has, indeed, hitherto been small, compared to the probable future increase; but it has been large, considering the short time since its properties were first made known, and the immense difficulties which attend the introduction of all new dyeing drugs: it appearing, by the act of the 13th and }4th of Charles II. ch. 2, that nearly one hundred years had elapsed before " the ingeni- ous industry of modern times had taught the dyers of England the art of fixing the colours made of logwood." And though indigo, the most valuable of ail dyeing drugs, had been known in Asia for at least two thousand years, the use of it was either prohibited or restrained for a considerable time in different European countries, from an erroneous belief that its colour was fugitive : so difficult has it always been found to bring dyeing drugs into their due esti- mation. But though the quercitron bark has been PERMANENT COLOURS. 210 employed only for so short a time, I flatter my- self that the account which I now offer of its properties and uses, will prove much more com- plete than any yet given of the properties and uses of any other dyeing drug, even among those which have been known for many ages. Had I done less I might well have escaped blame, " for (to use the words of Sir John Sinclair) no individual, or even nation, can carry any art or new invention to its ultimate state of per- fection. It must be improved upon for that purpose, by the investigation and experience of others." See his " Plan of agreement among the powers of Europe, &c. for the purpose of rewarding discoveries of general benefit to society.' 5 Article II. Of the juglans alba, or American hiccory. Not only the bark but the green leaves and the rinds of the nuts of this tree, yield an adjective colouring matter so very similar to that of the quercitron bark, that all the instructions which I have given respecting the latter, will be found applicable to the hiccory ; allowing only for the difference between their re- spective proportions of colouring matter ; that of the hiccory bark being about one-third less than what is contained in a like quantity of quercitron bark. It is this diffeienee, joined to the greater difficulty and expence of grinding the hiccory bark, it being very hard and tough, which has enabled the quercitron bark almost wholly to 220' PHILOSOPHY OF supersede the use of the hiccory ; for, excepting the prosubstantivc topical yellows, fbr which it does not seem to answer quite so well, there is, perhaps, no purpose to which the colouring matter of the hiccory may not be applied with effects as good as those resulting from the quer- citron bark; and I have sometimes thought' that some of the varieties of this tree might be preferable to the quercitron bark, for imitating the greenish lemon yellow of the weld plant on wool, with an aluminous basis. I say of some of the varieties, because there certainly are consider- able differences between the shades of yellow produced by the several varieties of the hiccory tree ; that, for instance, which Marshall calls juglans alba accuminata, produces a clear lemon yellow, whilst the juglans alba minima produces a fuller, though not a very bright, yellow ; and the juglans alba odorate, a yellow which is very full and also very lively. Generally, however, the hiccory bark em ployed in the way of calico printing, or topical dyeing upon linen and cotton, produces colours very similar to those of the quercitron bark, both upon the aluminous and ferruginous bases, and with no greater degree of stain or discolouration upon the parts intended to be kept white. This also is one of the vegetable colouring matters, of which the use was exclusively secured to me for a term of years by act of parliament. PERMANENT COLOURS. 221 CHAP. III. Of Madder — Rubia Tinctorum, Rubia Peregrina, and Rubia Manjifh. " Crescit profccto apud me certc, tractatu ipso admiratio antiqui- " talis : quantoque major copia herbaruin dicenda restat, tanto raa- " gis adorare priscoruni in inveniendo curam, in tradendo benigni- " tatem subit." C. P/.inu sccundi Histor. lib. xxvii. cap. i. The genus Rubia is of the natural order of Stella- tee* which, more than any other, abounds in roots affording the red colouring matter. It contains seven species, which have been accurately described ; though but three of these appear to have been employed by the dyers of Europe, viz. 1st. Rubia tinctorum, Lin. or rubia tinctor, sa- tiva, of Bauhin, (Pinax. 333) with annual leaves, a prickly stem, and perennial root. This is pro- perly the Zealand maduer, and appears to have been greatly cultivated in that province, during more than 300 years j the Emperor Charles the Fifth, having encouraged its cultivation, by par- ticular privileges conferred on the inhabitants of Zuyderzee, for that purpose ; and Great Britain * i. e. Having their leaves set round the joints of the stem, in the form of a star. 222 PIJlIX)SOPHY OF alone is supposed for a long time to have paid an- nually two millions of guilders (nearly c£ 200,000 sterling) for the purchase of Zealand madder ;* which is, I believe, never exported otherwise * Bei thollet appears to think it uncertain whether the mad- der of the ancients was similar to ours j though I cannot disco- ver any sufficient reason to doubt of its having been one of the species now employed by the dyers in Europe. It is, indeed, true, that in regard to this, as well as most other productions, the descriptions left by the Greeks and Romans 2re not so pointed and characteristic as they ought to have been ; but as far as they extend in this instance, they accord very well with the common dyer's madder. Dioscorides, under the name which it bore among the Greeks of Epv8o$aw, (Eruthodanon), describes its long square stem as being armed with hooks, and its leaves as being placed in the form of a star around the joints ; and after mentioning the colour of the fruit, as changing from green to red, and, finally, to black, he adds, that its long slender foots are red and serve for dyeing ; and that, for this purpose, they are cultivated with great profit in Galilea, and about Ra- venna, in Italy, as well as in Caria, Sec. (see lib. iii. cap. lfJo.) The description of Theophrastus (Hist. Plant, ix. c. 24) agrees very well with this by Dioscorides: Pliny mentions madder, with its use for dyeing wool, Sec. in three several places, under the name which it now bears, of rulia, adding its Greek name ; in one of them (i. e. lib. xxiv. cap. 1 1.) and in lib. xix. cap. 3. he says, " it grew both wild and by cultivation, from slips; and that the madder of Italy was most esteemed, especially that which grew around the villages near Rome j" he then com- pares it to a species of vetch (ervilia) and adds, that it had a prickly stalk with joints, surrounded each by Jive leaves spread- ing in form of an orb or star. " Verum spinosis ei caulis : geniculates hie est, quinis circa articulos in orbe foliis." PERMANENT COLOURS 223 than in a prepared state. To bring madder into this state of preparation, the roots, after being extracted from the earth, freed in some degree from the dust, and dried by a stove heat, are placed upon concave oaken blocks, each having six stampers plated at the bottom with iron bands, which (stampers) are moved or worked by- horses with suitable machinery. The first pounding separates and brings into the form of a powder the very small roots, with the skin or husk of the larger ones, and any earth which may have been left adhering thereto ; and this powder being sifted, is packed separately in casks, and sold at a low price under the name of mor mull ; but is commonly known in this country, only by the latter of these names, and employed exclusively for cheap dark colours. A second pounding separates about one-third of the remain- ing part of the larger roots, and this being sifted and packed separately, is denominated gort gemeen, ordinary powder, (of madder) and sold here under the name of gemeen or gemeens. The third and last pounding comprehends the residue, or interior, pure, and bright part of the roots, which, according to Mr. Miller, is packed under the name of " Icor kraps ;" but in this country, it is simply called crop madder.* Some- ' * The mull is called " garance courtc' by the French — the gemeen, '• garance mi-rohk j" and the crop, " garance tV-iV -• and also " garance grappe.' t 224 PHILOSOPHY OF times, after the midl has been separated, all the re- maining part is ground, sifted, and packed to- gether, under the name of onberoofde, which con- sists of about one-third of the gemeen, and two- thirds of the crop. In Zealand the madder is dried by a very moderate heat ; and the last pounding is chiefly performed by night; day-light being thought to detract from the brightness of the colour. Crop madder, if exposed to a damp atmosphere, attracts moisture, and is soon greatly injured by it. If the roots of madder be examined with a magnifying glass, the interior part will be found to contain a considerable proportion of specks or particles of a bright red colour, intermixed, or in contact with a kind of ligneous substance, which, as well as the cortical part, seems, unfor- tunately, to abound with a sort of brownish yellow colouring matter, called favsce by the French ; and this contributes to degrade the Jine red> which madder would otherwise afford; though the degradation may, in some degree, be obviated or diminished by extractingthe colouring matter in water, which is but moderately warm ; the brownish yellow tingent matter not being soluble so readily, and in so great a proportion as the other, so long as the heat of the menstru- um is below the boiling point. There is, also, another difference, which is, that the brownish yellow tingent matter, does not attach itself so permanently as the red, to the aluminous basis ; PERMANENT COLOURS. 225 and of this the dyers of the Turkey red avail themselves, by separating and discharging the former from the latter, after both have been applycd or dyed upon the cotton yarn, &c. ; employing, for this separation, a solution of soap with water heated often above the boiling point ; and thus obtaining a colour equal in beauty to any which cochineal would produce upon a similar basis. But this method of purifying the madder colour, by an abstractioa of the brownish yellow part, cannot be employed upon wool, which at a degree of heat so elevated, would be greatly injured by soap. Water of the ordinary temperature of the atmosphere, may be made to dissolve and ex- tract nearly all the red colouring matter from madder ; but to do this, it must be copiously employed ; and the colour will be more beautiful when the extraction is performed by cold, than if performed by hot water : alkalies increase the solvent power of water, and especially in regard to the brownish yellow (or fauve) part of its colouring matter ; whilst acids weaken or reduce the red part, if allowed to act upon it when ?msupported by an aluminous or other basis; water is capable of dissolving a larger proportion of the brownish than of the red tingent madder ; but for this purpose it requires a greater degree of heat. Bartholdi asserts, that the roots of madder, VOL. II, Q 22G PHILOSOPHY OF contain a large proportion of sulphate of magnesia " f and Braconnot found in them a very considerable quantity of potash, neutralized by the malic acid. See Ann. de Chimie for June, I8O9. D'Ambour- nay, and some others, have pretended that the roots of madder might be most advantageously and economically employed when fresh gathered ; but this pretence is contradicted by the general experience of dyers, who find that, if properly dried, and afterwards carefully secluded from moisture, they will improve by being kept one or two years, even in powder. Of the Application of Madder to Wool and Woollen Cloth. Though the red colour dyed from madder, upon wool impregnated with the aluminous basis, is less bright and beautiful than that of cochineal, it has the advantage of being cheaper and more durable ; and for these reasons it is greatly em ployed, especially upon the cloth worn by British soldiers : of the application of this basis (with tartar) upon wool and cloth, as a preparation for this and other extractive colouring matters, I have already given a sufficient account, at, and between pages 3S4 and S90 of my first volume ; and though SchefFer has directed a much larger proportion of tartar to be employed in this preparation, I am confident that he has done PERMANENT COLOURS. 227 so without reason, and that no advantage would result from such an augmentation of it. Wool or cloth being prepared, as described at the pages just mentioned, and good crop madder, at the rate of from four to eight ounces for every pound of wool or cloth to be dyed (according to the quality of the madder, and fulness of colour required) being put into a suitable quantity of water in the dyeing pan, and the water being gradually warmed, until it has become almost as hot as the hand can well bear, the prepared and moistened wool or cloth is to be dyed therein, by the usual management, taking care not to employ more than a scalding heat, until the colouring matter has been sufficiently applied ; after which, it is commonly thought expedient, (in prder more effectually tojix the colour) to make the liquor boil a few minutes, before the wool or cloth is taken out of it. In large dye houses, more than GOOlbs. in weight of cloth, is frequently dyed with madder at a single operation; and when this is finished, and the red part of the madder colour taken up by the cloth, the liquor appears to be highly charged with the remaining yellow part, which, not having so much affinity as the red for the aluminous basis, is not taken up by it in an equal proportion, so long, at least, as the heat continues below the boiling point. Whether the colour be in reality fixed more permanently by boiling the dyed cloths a few Q2 228 PHILOSOPHY OF minutes, as is commonly practised at the con- clusion of the operation, is a question which I am afraid to answer, as the results of several trials which I have made were not uniform ; but if it should be found expedient to employ a boiling heat for this purpose, all danger of any harm from it might be avoided, by giving it with clean water, in a separate pan, to which the cloths might be. removed, after having already imbibed suflicient colour, with only a scalding heat ; in this way there would be no danger of increasing the extraction of the yellowish brown colouring matter, or promoting its application either to the cloth or the aluminous basis. When it is thought desirable to render the madder red brighter than it can be made by alum and tartar only, (as mordants) some dyers are accustomed to add a small proportion of nitro- muriate of tin to the other mordants, in preparing the cloth. But a more beneficial effect would be produced by reserving this nitro-muriate, and employing it with the madder (putting both into the water at the same time) for the dyeing operation ; because, the acids, combined with the tin, will, in a considerable degree, obstruct the extraction of the yellowish brown part of the colouring matter; and a similar effect may be produced by employing a little sour bran liquor along with the madder. Sometimes orchali and Brasil wood are combined with madder, to render PERMANENT COLOURS. 22.9 its colours more rosy ; but their effects are not lasting. Having witnessed the utility of glue, in purify- ing and brightening the colours of morus tincto- ria, and quercitron bark, I tried it with madder, though unsuccessfully ; the latter appearing to be destitute of tannin, or any matter capable of being separated or precipitated by an animal jelly. In regard to the application of tin, or rather the solutions of that metal, as a basis for the madder red upon wool, I think myself warranted, by numerous experiments, to recommend it, where colours approaching the scarlet from cochineal are wanted, though I do this in opposition to the high authority of MM. Berthollet, (father and son) who assert, that their multiplied experi- ments with this mordant have not produced any beneficial effect worthy of notice, in regard to the madder colour, (see Elements, &c. torn. ii. p. 122 and ]25 ;) and I can only account for this assertion, so much at variance with my own ample experience, by supposing, that in all their trials with madder, the nitro-muriate of tin was ex- clusively employed, (as it has been by the dyers) to prepare the cloth, and wholly omitted in the second or dyeing operation with madder ; and certainly when so employed, the colour will be but little brightened or improved ; though, if a part of this nitro-muriate be reserved and mixed with the water, before the madder is put into it, 230 PHILOSOPHY OF so that its acidity may obstruct the extraction of the yellowish brown part of the madder colour, a very sensible increase of its vivacity will soon become evident : or, even if the whole of the solution of tin be employed to prepare the cloth, a similar effect may be obtained, by mix- ing a portion of tartar conjointly with mad- der in the dyeing vessel, as the tartaric acid will be equally efficacious with the nitro-muriatic for impeding the extraction of the brownish yellow part of the madder colour. And the effect of the little thereof which may be extracted and taken up by the cloth, might be nearly overcome, by adding a very small portion of cochineal to the madder. Sour bran liquor will operate in the same way as tartaric acid, but neither should be employed in excess, least it should reduce or weaken the red colour. Cloth prepared with a solution of tin and tartar should not be rinced previously to their being dyed, unless the solution has been used to excess. I have already mentioned (at p. 495 of my first volume) that the madder colour, when dyed upon the basis of tin, had been found, in my experiments, to be extremely durable ; and when properly dyed, it certainly is but little inferior in vivacity to that of cochineal, and might, perhaps, be made even to surpass the latter, if the pure red part of the root could be exclusively applied with the oxide or solution of tin j or if, after being applied conjointly with the brownish yellow PERMANENT COLOURS. 231 part, this last could be separated from the former, by the means employed to purify and enliven the Turkey red, or by any other means which would not injure either the cloth or the colour. For as the Turkey red, though dyed upon the alu- minous basis, is, by this purification or separa- tion, rendered nearly equal in vivacity and beauty to the finest cochineal scarlet, which has been dyed on a basis derived from tin, there is reason to conclude, that by a substitution of the latter basis, a colour more excellent even than the best scarlet might be produced with such purifica- tion. But, unfortunately, this substitution is im- practicable upon either linen or cotton, because there is but little affinity between either of them and the oxide of tin ; and when the substitution is made in regard to wool, the means by which the madder colour is afterwards purified on cotton, cannot (as was lately observed) be employed upon wool, without destroying it. Such is the affinity of madder for wool, that when both are put into water and kept at a scalding heat for one hour, the wool will imbibe a full, though brownish red colour; and broad- cloth boiled for half an hour in water moderately acidulated by sulphuric acid, and afterwards dyed, unrinced, with madder, will acquire a better red ; which, though less bright and less permanent than that dyed upon the aluminous basis, will bear expo- sure to the sun and air, during two months, with- 232 PHILOSOPHY OF out any considerable injury. Cloth treated in the same way with water acidulated by the nitric, muriatic, tartaric, and citric acids, and dyed with madder, took reds of different shades, but of nearly equal permanency. 'These effects were to roe very unexpected. Linen and cotton, how- ever, took no colour by the same treatment and means. A strong proof of the greater affinity of some colouring matters for ammal than for vegetable substances. The remarkable effect of madder, in giving its red colour to tiie bones, but not to the. soft parts of animals, with whose food it had been mixed,* appeared to indicate a considerable attrac- * Beckman, in his history of inventions (vol. iii.) mentions Lemnius, (a Physician in Zealand, where madder had been long cultivated) as being the first writer who had published this fact, and he quotes the following words from the treatise of Lemni- us de Miraculis occultis naturae, punted at Cologne, in 1581, viz " Erythrodaoum seu rubta ossa pecudum sandicrao ruben- tique colore imbuit, si quando herbam virentem depasta sunt, intacta etiani radice, quae rutiia existet ; quod etiam in elixis decoctisquej ejuspecoris camibus peispici potest, et in ovis, quae rubicande colore radicis decoct o fucantur." Beckman acknow- ledges, indeed, that this passage does not occur in the first edition of the work, piinted in 8vo. in the year 155Q, but supposes it to have been contained in the second, which was printed in lG6i ; and that a knowledge of this fact was thus obtained by Mizaldus, who, in his " Centuriac novem memora- bilnm, utilium ac jucundorum," printed in 8vo. at Paris, in \5Q6, states the same faa in almost the same words. It will have been seenin the passage just quoted, that Lemnius PERMANENT COLOURS. 233 tiori between calcareous earth and the colouring matter of t ; • i s root, and I v. as induced by it to employ the former as a basis for the latter, in dyeing both upon wool and cotton,; but the effect did not answer my expectation ; as neither lime recently burnt, nor the carbonate of it, when mixed with madder in v/ater, produced colours more lively a->d permanent than madder alone. But broadcloth, boiled in water with lime and sulphuric acid, in such proportions as to neutra- mentions this effect upon the bones of animals, as having |>een pro luf*ed by their feeding only on the leaves without the roots of madder ; and Beck man says he has proved in his " Expe- riments emendandi RubicE usotn tinctorum," that the green leaves of madder contain, and really communicate, a red dye. Though this effect of madder upon the bones of animals had been thus mentioned in the! 6th century, by Lemnius and Mizaldus, it was forgotten and become unknown, until the late Mr. John Belcher (a surgeon) happened to dine with a calico printer in Surrey , about the year 1 736, and observed that the bones of some pork which made a part of the dinner, were red ; when, upon expressing his surprise at the fact, he was told, that the llOg from which it was tiken, had been fed on bran, after it had been employed in one of the operations of calico printing, and had thereby imbibed the colouring matter of madder roots. Mr. Belcher afterwards ascertained, by adding some powder of madder root^ to the food of dunghill fowls, that a similar redness was thereby communicated to their bones j and he gave accounts of his observations and experiments to the Royal Society, which were printed in the Phil. Trans. No. 442, and No. 443, (1736), and these were followed by others from M. du Hamel du Monceau, in 1740. 234 PHILOSOPHY OF lize the latter, and afterwards dyed with madder, took a lasting red colour, though not so bright as when dyed upon the aluminous basis. Cotton, however, being treated in the same manner, was but slightly discoloured. Broadcloth, prepared with a nitrate of lime, and dyed with madder, took an orange colour ; but cotton treated in the same way, remained almost white. Muriate of lime with madder, pro- duced a brownish red, upon wool which suffered but little by thirty-eight days exposure to the sun and air. Broadcloth, prepared with sulphate of magnesia, and dyed with madder, took a salmon colour of but little durability. Cotton treated in the same way, remained nearly white. Broadcloth, boiled with muriate of barytes, and afterwards dyed with madder, took a dull red, of but little durability. Broadcloth, boiled with muriate .of antimony, and dyed (unrinced) with madder, took a very good and permanent red : less bright, indeed, "than that dyed with solutions of tin, but pre- ferable to that commonly dyed upon the aluminous basis. Broadcloth, treated in the same way with nitro-muriate of cobalt and madder, obtained a reddish brown colour ; with nitrate of bismuth and madder, a dark brownish red ; with nitro-muriate of zinc, a reddish orange colour ; with nitrate of lead, an orange, inclining to the PERMANENT COLOURS. 235 brick colour ; and with sulphate, nitrate, and muriate of copper, separately, browns, inclining more or less to yellow. Iron, dissolved by the sulphuric, nitric, and muriatic acids, and applied severally as a basis to cloth, produced with madder various shades of" dark coffee colours, somewhat approaching the violet. Silk, macerated during twenty-four hours in a diluted muriate, or nitro-muriate of tin, not more than blood-warm, and afterwards dyed, unrinced, with madder in water moderately warm, acquired a lasting red of considerable vivacity ; and being macerated in a cold solution of alum, instead of the solution of tin, it obtained, in the same way, from madder, a permanent red, similar to that commonly dyed by the same means on wool or cloth ; but as the most lively and beautiful colours are generally required for silk, those of madder are but rarely employed with this substance. On Linen and Cotton, the madder colour is eminently useful with the basis of alum ; and for dark colours, with that of iron ; which, in- deed, are the only bases employed in calico print- ing, as was observed in my first volume j where, (i. e. between pages 35 8 and 378) I have describ- ed the preparation of the acetate of alumine and that of iron, as well as the means and methods of applying them to calico intended to be printed ; and I have, moreover, given a concise account of the manner in which the 286 PHILOSOPHY OF calico, when printed, and afterwards cleansed, is to be dyed with madder ; but of this last opera- tion, it may be proper that I should furnish some additional explanations. Calico, when intended to be printed and dyed with madder, should be first carefully and thoroughly bleached ; and even when this has been done, it should be immersed for some time in an alkaline lixivium of proper strength, and (after being rinccd) macerated a few hours in water acidulated by sulphuric acid, to dissolve and remove any earthy matters which might otherwise, not only degrade the madder red, but fix it on the parts intended to be kept white. The proportion of madder to be employed must depend upon the extent of surface intended to be coloured by it, and the depth or fulness of the colours desired : when very full dark reds are to be produced, it will be best to employ but half of the madder at once, and repeat the operation with the other half, in order to avoid that alteration and degradation, which the madder colour suffers, when kept longer than usual, even at a degree of heat much below the boiling point. And, for this reason, the dyeing should always be stopped as soon as the colours have been sufficiently rasied: and, I am persuaded, that to obtain the brightest reds with the least discolouration of the white parts, it is always advisable that the dyeing liquor should never be made much hotter than the hand can bear j and that the boiling, if it be PERMANENT COLOURS. 237 deemed expedient, should take place afterwards with clean water in a separate pan ; which will also remove a part of the discolouration of the white parts. Commonly two or three pounds of madder for each piece of calico are crumbled into the water, and being well mixed therewith, the pieces, tacked together by their ends, are put into the dyeing liquor as soon as it becomes blood- warm, and afterwards turned through it con- stantly, backwards and forwards over the winch, pressing down those parts of the calico which rise above the surface. It is desirable, that the colouring matter should have applied itself suffi- ciently within the space of an hour, and then the pieces should be turned out of the liquor imme- diately, and carried as soon as possible to a stream of running water and be there well washed, to obvi- ate the S2iottbig, to which they would otherwise be liable ; and when this has been done, they are to be boiled in water with bran, (which removes a por- tion of the brownish colouring matter) and after- wards exposed upon the grass, with the well- known management and precautions ; and this alternate boiling with bran, and exposure on the grass, are to be repeated until all discolouration by the madder has been removed from the parts to which no mordant or basis was applied, and some of the brownish part of the colour also detached from the red parts. The use of bran, for the purpose just mentioned, has been found to be unnecessary 238 PHILOSOPHY OF in the East Indies, by those who have there prac- tised the European methods of calico printing ; exposure to the sun and air, and the application of water, being abundantly sufficient in that climate to produce the desired effect. When sumach is intended to be employed with madder, it is thought best to apply it first. or separately, at the rate of about one pound of that which is brightest, and of the best quality, to each piece of calico, putting it into the water whilst cold, and turning the pieces by the winch, fifteen or twenty minutes through the liquor as soon as it becomes blood-warm, and taking care not to make it hotter than the hand can bear ; after which the pieces should be rinced in water with a very little sulphuric acid, and dyed im- mediately with madder, or kept under water until dyed, otherwise the sumach, by absorbing oxygene from the atmosphere, will produce a troublesome discolouration of the parts intended to be left white. It has been found practicable withil a few years, to produce from madder upon calicoes, a rose or pink colour, by employing it with a large proportion of bran, which, by its acidity, hinders, in a great degree, the extraction of the brownish yellow part of the colouring matter of the madder, and its application to the calico; an effect similar to that which I lately mentioned as produced by the acid of tartar, in dyeing wool or woollen cloths. This employment of bran, PERMANENT COLOURS. 23!) was lately brought into notice by a journeyman calico printer, named Growse, and the colour obtained by it was called Growse's pink. His process (which was cheaply purchased for one hundred guineas, by a subscription among the master calico printers,) was performed by putting into a copper, or dyeing pan, with water, three bushels of bran, and making the liquor boil about five minutes, then suffering it to cool, and add- ing sixteen pounds of the best crop madder, which, by stirring, is to be well mixed therewith, and in this mixture pieces of calico, previously impregnated, or printed with sti^ong acetate of alumine, and afterwards well cleansed, are to be dyed, by passing or turning them quickly six or eight times backward and forward through the liquor ; then rincing and washing them until fit for sale, without either branning or bleaching, as the acid derived from the bran served, in a great degree, to protect the white grounds from discolouration. It is, however, necessary to the success of this operation, that the proportions of bran and madder should be nicely adjusted, for where the former is in excess, the colour will be weak, and where it is deficient, the colour will be less rosy, and the white grounds more dis- coloured. I have repeatedly found that a similar effect (i.e. that of obviating, in a considerable degree, the discolouration of the white ground^) might be 240 PHILOSOPHY OF obtained by employing along with madder about one sixth of its weight of the best sumach ; but this addition made the red incline more to the orange tint. The leaves and tops of the plant, which I received from Mr. Alderman Prinsep, under the name of d'hoivafy as mentioned in the preceding chapter, produced the like effect of hindering a discolouration of the white grounds, and without any sensible change of the madder red. A solution of glue being put along with madder into the dyeing vessel, manifestly ob- structed the combination of the colouring matter with the aluminous basis, so that only a kind of salmon colour was produced. M. Haussman (now of Longleback, near Col- mar,) strongly recommends, in dyeing with madder, t'ie addition of about one fifth or sixth of its weight of either powdered chalk or quick lime, to decompose or counteract a portion of sulphate of magnesia, supposed to be naturally contained in madder. Pie adds, that it was not until he had removed from Robec, near Rouen, where the water naturally holds carbonate of lime (chalk) in solution, that he discovered the error of an opinion which had been entertained by himself and other calico printers in that neigh • bourhood, who imagined that the superiority of their madder reds, was due not to this quality of their water, but to certain useless drugs which they employed, and withheld as a great secret s PERMANENT COLOURS. 241 and he asserts, that in all situations where the water does not contain some portion of carbonate of lime, the utility of putting it into the dyeing vessel along with madder, may be rendered manifest, by taking two pieces of calico, printed with exactly the same mordants, &c. and dyeing them separately with the same madder, and with no other difference than that of putting chalk into one vessel and not into the other ; as the red dyed with the aid of chalk, will be found much brighter and more durable than the other 3 and more capable of supporting the action of bran, soap, &c. See Ann. de Chimie, torn. x. and lxxvi. I have in vain tried, with a great variety of means, to produce a j)rosubstantive red from madder. Its colouring matter seems incapable of being fixed upon linen or cotton by any basis, unless the basis be applied separately from the colouring matter. After these observations concerning topical or partial dyeing on calico with madder, I proceed to the application of it generally , (and without any reservation of white or other coloured parts,) to linen and cotton, either woven, or only spun into thread or yarn. Two kinds of red colour are dyed from madder upon linen and cotton ; one of these is the common madder red, and the other the Turkey red, to be treated of in the next article ; both VOL. II. K ■242 PHILOSOPHY OF are dyed upon the aluminous basis, but with i considerable difference in regard to the aux- iliary means and modes of employing them. For the common madder red, linen or cotton, after being boiled in a weak lixivium of potash or soda, and well rinced and dried, is to be mace- rated in a decoction of powdered galls, employed after the rate of four ounces to every pound of linen or cotton to be dyed ; and being equally impregnated with the soluble matter of the galls, and afterwards dried, the linen or cotton is to be alumed, by soaking it thoroughly in a saturated luke-warm solution of alum, em- ployed also at the rate of four ounces to each pound of linen or cotton ; after having previ- ously neutralized the excess of its acidity, by add- ing to the solution one ounce of soda for every pound of alum : this being done, and the linen or cotton moderately and equally wrung or pressed, it is to be well dried, and afterwards alumed a second time, dissolving for that pur- pose half as much alum as for the first aluming, and adding to it the residue of the former solu- tion. After this second aluming, the linen or cotton is to be again well dried, and then rinced,) to remove any superfluous part of the alum which may not have been united thereto. By substituting the acetate of alumine (for- merly described) for the solution of alum, just mentioned, a more beneficial effect might b« PERMANENT COLOURS. Obtained; but if would be attended with a con- siderable increase of expence. The use of galls, in this operation, will be readily conceived, by recurring to what I have mentioned, at p. 355, and 357, of my first volume, concerning the effect of myrobalans* when employed by the Hindoos^ in causing a more copious precipitation, and a more intimate union of the earth of alum, in or with the calico which had previously imbibed their astrin- gent matter. That this is the only use of galls so employed, I presume, because I have found, by repeated trials, that when employed with madder in the dyeing operation, they add nothing to the durability of the colour.* Linen or cotton which has been thus impregnated with the aluminous basis, is to be dyed with the best crop madder^ employing about three-fourths of a pound thereof * For every other purpose, except that of decomposing the alum, and increasing the precipitation of alurnine, and, perhaps, its closer union with the fibres of cotton, galls appear to do harm rather than good with madder, by diminishing the vivacity of its colour, and giving it a brownish tinge, without the smallest increase of its durability ; on the contrary, I have observed, that when calico printed with acetate of alumine was divided, and one half dyed with madder only, and the other with madder and galls, the colour of the latter, besides a considerable degradation, was injured by being boiled with soap, and also by being exposed to the weather sooner, and in a degree considerably greater, than the half which had been dyed with madder om'y. R !» 2U PHILOSOPHY OF for each pound of the substance to be dyed, with the usual management and precautions ; parti- cularly that of raising the heat gradually, so that it may begin to boil in about fifty, or at most, sixty minutes, and taking it out of the dyeing liquor when the boiling has continued but a very few minutes ; after which, being slightly rinced, it is to be dyed a second time in the same manner, and with the same quantity of madder. After the second dyeing, followed by the usual rincing and drying, it is commonly thought expedient to macerate the linen or cotton in a luke-warm solu- tion of soap, (employing for that purpose about two ounces of the latter to each pound of the former) in order to give more vivacity to the red colour, and remove any adhering, but un- combined, colouring matter ; afterwards rincing and drying, as usual. Some persons have advised a weak solution of glue to be applied to the cotton, after it has been alumed, as before mentioned, believing that it would operate favourably in uniting the alumine more closely with the cotton and the tanning principle of the galls, and moreover give animal properties to the cotton. The effect of this application has not, however, appeared to produce any considerable benefit in the several trials which I made with it. By substituting the nitrate of alumine for common alum, a red somewhat brighter was produced; but, perhaps, the difFe- ♦ PERMANENT COLOURS. 24! rence would hardly compensate for the difference of expence. Sumach is sometimes employed instead of galls, as a preparation for the madder red, and sometimes both are employed together. It can hardly be necessary for me to mention, that piece- work, when dyed, is made to pass through the dyeing liquor by turning it over the winch ; and that thread or yarn in skeins is to be put into the liquor upon sticks. ARTICLE II. Riibia peregrim, Lin. Smyrna or Levant Madder, and its Application for dyeing the Turkey Red. The leaves of this species are perennial, com- monly in fours, elliptic, shining, and smooth on the upper surface. It has been found wild in some few parts of England ; but for the use of dyers has been all imported, chiefly from Smyrna, Cyprus, and Provence. It is called ali-zary, or lizary by the modern Greeks, and foijoy, or fouoy, by the Arabs. The best is cultivated in Bceotia, along the borders of the Lake Copais, and in the Plain of Thebes. It grows also in large quantities at Kurdar, and other places near Smyrna, as well as at Cyprus, whence, in 1760, M. Bertm x one of the .French ministers, procured a large quantity of the seeds, which have since produced all the madder of Provence. Its roots have less parenchyma than those of the Zealand •24 6 PHILOSOPHY OF madder ; but they afford a colour somewhat brighter, and are, therefore, always preferred in dyeing the Turkey red. But as the people of the Levant, by whom this species is chiefly cul- tivated and exported, have not had ingenuity and industry sufficient to improve it like the Zealanders, by pounding and separating the skin and inferior parts of the roots ; but have left them in their natural state ; (whence they are com- monly called madder roots in this country) the dyers of woollen cloths have not been able to produce from them, colours so bright as those obtained from the crop madders ;* the finer co- louring matter of the former being degraded by that of their skins and smaller roots ; an in- convenience which is overcome by the dyers of Turkey red, in the last part of their process, as will hereafter be explained. The Levant dyers never employ the fresh gathered roots. According to the best information which I have been able to obtain, the complicated process by which the Turkey red can alone be dyed, was many ages ago practised, and perhaps invented, by the inhabitants of Malabar and Coromandel ; but with this difference, that instead of madder, they employed the roots of the oldenlandia umbel- lata, which will fall under our particular notice in * Very recently, and since the above was written, mills have been erected in this country, to give the madder roots the same preparation as that of Zealand. PERMANENT COLOURS. 247 the next chapter. From India the knowledge and practice of dyeing this admirable colour, seems to have been carried to Persia, Armenia, Syria, and Greece, and, after a long interval, to France, in consequence of the accounts trans- mitted, at different times, by the ambassadors of that nation at Constantinople, of the means and methods employed to dye this red, particularly at Andrinople, and of the instructions which, on the faith of those accounts, the French govern- ment published, in 1765, under the title of" Me- moire Contenant le procede de la Teinture du coton rouge incarnat d y Andrinople sur le coton file." By. this mode of introduction, the colour under consideration obtained, in France, the name of rouge dJ Andrinople^ and in Great Britain that of Turkey red. The instructions, so published, were first car- ried into practice chiefly at or near Rouen, in Normandy ; but for a considerable time they were attended by numerous failures and disap- pointments ; though at present the Turkey red, from various improvements suggested by obser- vation and experience, is supposed to be dyed in that part of France even more permanently, and with greater lustre, than in Greece or any part of the Ottoman Empire, or, I may probably add ? of Europe. In the year 1790, M. Pierre Jacques Papillon, who, after having been employed in dyeing the Turkey red in France, had practised it success- 248 PHILOSOPHY OF fully at Glasgow, received a premium from the Commissioners and Trustees for Manufacturers in Scotland, in consideration of his communicating to Dr. Black, then Professor of Chemistry at Edinburgh, a description of his process ; though, by agreement, it was to be kept a secret during a term of years, for the use of M. Papillon exclu- sively ; and that term having expired ; and the process having been published, I shall subjoin an account of the several operations of which it consisted, with remarks upon each, intended prin- cipally to explain its difference, where any occurs, with the correspondent operations in the two processes generally practised at Rouen, as they have been very lately published, by M. Vitalis, " Docteur es Sciences de l'Universite Imperiale ; Professeur des Sciences Physiques au Lycee de Rouen, &c." in his " Manuel du Teinturier sur fil and sur Coton file."* ' Until within a few years, the Turkey red was exclusively dyed upon cotton spun into yarn, but not woven : though, since Mr. Arkwright's invention, (by which as Mr. Wilson observes, " the cotton wool is carded and drawn forward length- way of the harle, or filaments ;" and being so spun) the thread or yarn is made much stronger, and also much more equal, and muslins woven from it, may with care be made to receive the Turkey red dye, and be even variegated by a reservation of white spots, &c. by passing the muslin through cylinders after it has been macerated in the oleagi-, nous and other steeps, (in order that the latter may be erfually expressed as is done with other piece-work which has ira- PERMANENT COLOURS. 249 An Account of the Process for dyeing Turkey Red, as practised by M. Pierre Jacques Papillion, viz. Step 1 . or Cleansing Operation. For 1 OOlb. of cotton take lOOlb". of Alicante barilla 20lb. of pearl ashes 1 OOlb. of quick lime. Mix the barilla with soft water in a deep tub, having a small hole near its bottom, which is to be stopped at first with a peg, but covered within by a cloth supported by two bricks, in order that the ashes may be hindered from either running through the hole, or choaking it, while the lye filters through it. Under this tub, another is to be placed to receive the lye ; and pure water is to be repeatedly passed through the first tub, to form lyes of different strength, which are to be kept separate until their strength has been examined. The strongest required for use, must swim or float an egg, and is called the lye of six degrees of the French hydrometer, or " pese- liqueur." The weaker are afterwards brought to this strength, by passing them through fresh barilla ; but a certain quantity of the weak, which bibed only a single mordant) and finally, when the muslin has been dried, and previous to the dyeing operation, printing a strong reserve of oxalic or citric acid upon the parts intended to be preserved white. 250 PHILOSOPHY OF is to mark two degrees of the above hydrometer, must be reserved for dissolving the oil, the gum, and the salt, which are used in subsequent parts of the process. The lye of two degrees is called the weak barilla liquor, the other is called the strong. Dissolve the pearl-ashes in ten pails, (containing four gallons each) of soft water, and the lime in fourteen pails. Let all the liquors stand until they become quite clear, and then mix ten pails of each. Boil the cotton in the mixture five hours, then wash it in running water and dry it. Remark. — At Rouen two courses of operations are practised to produce the Turkey red j one is called the grey course, (la marche en gris) and the other the yellow course, fla marche en jaune). In the former, the cotton, after being alumed, re- ceives no more oil, but goes to the dyeing vessel, retaining the grey colour, which naturally re- sults from its being impregnated with alum and galls in combination. But in the yellow course, the cotton, after being alumed, is again immersed in the oleagenous mixtures or steeps, to be men- tioned hereafter, by which it acquires a yellow colour. The grey course may consist either of fifteen steeps, or of nineteen ; and the yellow of twenty. The first of these courses has most similitude to that of M. Papillon, and it is this which I shall principally compare with the latter ; PERMANENT COLOURS. 261 occasionally noticing any peculiarity in the yellow course. At Rouen the first, or cleansing, operation (called decrusage) is performed with a very weak lye of soda, of only one degree of the hydrometer, pese- liqueur or areometre of Beaum6, employing 1 50 gallons to iOOlb. of cotton, which is to be boiled therein six hours, then drained, well rinced in run- ning water, and afterwards dried. This operation is intended to free the cotton from all impure or extraneous matters ; but not to produce effects like those of bleaching by exposure upon the grass, which it was, until lately, believed would lessen the durability of the colours to be subse- quently d/ed. Step 2. — Bain bis, or grey Steep. Take a sufficient quantity (ten pails) of the strong barilla water in a tub, and dissolve or dilute in it two pails-full of sheep's dung ; then pour into it two quart bottles of oil of vitrol, one pound of gum arabic, and one pound of sal ammoniac, both previously dissolved h\ a sufficient quantity of weak barilla water ; and, lastly, twenty-five pounds of olive oil, which has been previously dissolved, or well mixed, with two pails of the weak barilla water. # The materials of this steep being mixed, tramp or tread down the cotton therein, until it is well 252 PHILOSOPHY OF soaked : let i$ steep twenty-four hours, then wring it hard and dry it. Steep it again twenty-four hours, and again wring and dry it. Steep it a third time twenty-four hours, after which, wring and dry it ; and lastly, wash it well and dry it. Remark. — The steep here precribed, contains three ingredients not employed, so far as I can recollect, by any other person ; and one of these, 1 mean the sulphuric acid, seems to indicate a want of chemical knowledge in M. Papillon, be- cause, by neutralizing the soda, it must obstruct the efiect which the latter is intended to produce, (i. e. that of rendering the oil miscible with water) or at least render a greater proportion of it necessary, in order to obtain that effect. In regard to the other two of these ingredients, viz. the gum and sal ammoniac, I shall only observe of the former, that the quantity is by much too small to produce any considerable effect, either good or bad, without offering any opinion of the latter ; because I am unable to form even a conjecture, respecting the purpose which it may have been intended to answer. Did M. Papillon wish, by these additions, to give to his process some appearance of novelty or peculiar it y which might render it more deserv- ing of a reward ? At Rouen, the bain bis is prepared by steep- PERMANENT COLOURS, 9-r-j ing twenty-five or thirty pounds of my first volume) previously dissolved in two quarts of water, and mixed with eight ounces of single aquafortis ; and having equally dispersed this mixture through the boiling solution of soap, by stirring, &c. the cotton is put into it, and boiled with the same precautions as in the brightening operation, until the desired effect has been ob- tained ; which is to be discovered by frequent examinations. Care must be taken not to em- ploy more nitric acid, or aqua fortis, than the quantity here mentioned, least it should decom- pose the soap, and cause the oil to separate, and rise to the surface of the liquor. M. Vitalis supposes, that a metallic soap is form- ed in this operation ; the oxide of tin being, as he thinks, dissolved by the soda. That a solution of tin, employed in this way, should add something to t the vivacity of the colour, is very probable from what I have seen of its effects upon the madder red. But I am convinced that it can add nothing to its fixity on cotton, un- less the nature of the latter should have been greatly changed by the impregnations which it receives \yy the operations recently described. M. Vitalis^ PERMANENT COLOURS. 263 adds, however, (p. 98,) as a discovery of his own, and one which, as he says, has been successfully tried upon a large scale, that an acid sulphate of rotash, employed with soap in the proportion of two or three pounds of the former, to one hundred pounds of cotton, will answer all the purposes of the muriate of tin, giving a particular and very pleasing shade to the Turkey red. In regard to the second of the grey courses employed at Rouen, I must observe, that it differs from the first, by having two additional repeti- tions of the grey steep, (with dungj and four of the white steep, (after the first) with two gall and two alum steeps. In the yellow courses, after the first gall and the first alum steeps, two of the white are interposed, with two of the salt steeps (sel) in addition to the like number given before the first galling; and these are succeeded by a second gall steep, and a second maceration in a saturated solution of alum; after which, the cotton, being well dried and then rinced, is dyed with Provence madder alone, in the proportion of two pounds and one half of the latter to each pound of cotton, or with a like quantity of Provence and Smyrna madders mixed in the proportion of one-third of the latter, to two-thirds of the former. This yellow course, as may be supposed, is intended to pro- duce the richest and most durable colour. M. Vitalis asserts, (p. 100 ? ) that it is impossible 264 PHILOSOPHY OF to produce a fine and permanent Turkey red, without employing in the different operations, forty pounds of oil for each lOOlbs. of cotton; and that the stove heat for drying, ought not to be less than 55 degrees of Recur mur's scale, which is equal to 1 58 of Farenheit's. To this account of the different courses and operations, employed to produce the colour in question, I shall subjoin an extract of certain ob- servations respecting it, publibhed in the 26th vo- lume of the Ann. de Chimie, by M. Chaptal, (late minister of the interior of France,) which are the more valuable, as being the result of a great portion of chemical science, added to an extensive practical acquaintance with these ope- rations, and their effects.* " It is known," says M. Chaptal, " that cotton does not take the madder red permanently, unless it has been sufficiently impregnated with oil. This , preliminary preparation is given to cotton by a cold saponaceous liquor, formed by a com- bination of oil, with a weak lixivium of soda. All kinds of soda, and of oil, however, cannot be employed for this purpose. In order that the soda may produce suitable I effects, it must be caustic, and contain but little muriate ; and this * See also, 1' Art de la Teinture du Coton en Rouge, &c. par M. J. A. Chaptai, Membre, et Tresorier du Senat, Grand Officier de la Legion d' Honneur, &c. &c. 8vo. PERMANENT COLOURS. 265 causticity must be produced by calcination, and not by an admixture of lime, which gives a brown- ish tinge to the red. "The carbonate of soda, and soda mixed with a considerable proportion of muriate, will com- bine but imperfectly with oil j and, therefore, soda either long prepared, or impure, is unfit for this purpose. " The choice of the oil is of as much importance as that of the soda. The former, to be good, should unite very perfectly with the lye, or lix- ivium of the soda, and remain in a permanent state of combination. The oil fittest for this dye is not fine oil, but that which contains a large portion of the extractive principle.* The former * The oil employed by the dyers of Turkey red in Great Britain, is imported chiefly from Italy under the name of Galli- poli-oil. Alter the finest olive oil which rises to the surface has been drawn off, the heavier, which is combined with a consi- derable portion of mucilage, is separated from the dregs at the bottom of the cistern, and this constitutes the Gallipoli oil. Its mucilaginous part, enables the oleaginous to unite, and form a mixture of a milky appearance, with a weak lixivium of soda, which the purer oil would not do. If when this mix- ture is formed, it preserves its milky appearance 24 hours without any separation or collection of oil in globules upon the surface, it is deemed suitable for the Turkey red dyers. In the East Indies, whence the Turkey red was derived, the oil of sesamum, (obtained from the seeds of the vanglo plant) is commonly em^ ployed for this purpose, (as, indeed, it is by the Turks) and when this is wanting, they substitute hogs' lard, as will be seen in tny 26G PHILOSOPHY OF does not preserve its state of combination with the soda, without such a degree of strength in the lye as would prove injurious to the subsequent operations. The latter forms a thicker and more durable combination, and requires only a weak lye of one or two degrees. u The necessity of producing a perfect and in- timate combination of the oil and the lye of soda, be readily perceived, by considering that the lye is only employed to divide, dilute, and con- vey the oil in an equal manner to all the, parts of the cotton, and, therefore, if the oil be not- well mixed, the cotton made to pass through this mix- ture will take the oil unequally, and the colour be but badly united. Hence it happens that the next chapter ; and, indeed, the Abbe Mazeas has asserted, in a *' Memoire" printed among those of the Royal Academy of Sciences at Paris, (viz. those of the " Scavans Etrangers" torn. It.) that he had produced better effects in this way with hogs' lard, than it was possible for him to do by any other greasy or oily matter ; and, we are informed by Professor Pallas, that the Armenians, who have been, by the troubles in Persia, driven to AsJracan, do there successfully employ fish oil to dye the Turkey red. It seems, therefore, that animal oil, or fat, will answer the purpose in question as well as the vegetable. The circumstance of most importance seems to be, that of not employing those oils which are called drying oils, such as that of lintseed, which is said to blacken the colour in some degree, probably by absorbing oxygene, and it seems to be this property, which has caused it to be employed to improve the black colour dyed upon cotton. PERMANENT COLOURS. 267 workman places the whole secret of a well uni- ted and strong colour, in the choice of good oil and proper soda : and, consequently, the oil ought to be rather in excess than in a state of absolute saturation, for in the latter case it would abandon the cotton in the subsequent washings, or rin- cings, without benefiting the colour. " When the cotton has been properly impreg- nated with oil, it is subjected to the operation of galling. The use of the gall-nuts is attended with several advantages : 1st. The acid which they con- tain, decomposes the saponaceous liquor with which the cotton has been impregnated, and fixes the oil on the stuff. 2nd. The character of anima- lisation which the galls possess, and impart, pre- disposes the cotton to receive the colouring mat- ter. 3rd. The astringent principle unites with the oil, and forms with it a compound which darkens at it dries, which is not very soluble in water, and which has the greatest affinity with the co- louring principle of the madder. The dyer may acquire a competent knowledge of this last com- bination, and study its properties, by mixing a decoction of gall-nuts with a solution of soap. " It follows from these principles : 1st. That the place of the gall-nuts cannot be supplied by any other astringent, let the quantity employed be what it may. 2nd. That the decoction of galls ought to be employed when warm, that the de- composition may be speedy and perfect. 3rd. 268 PHILOSOPHY OF That the galled cotton ought to be speedily dried, in order to prevent its assuming a dark colour, which would injure the brightness of the red in- tended to be given to it. 4th, That dry weather ought to be chosen for the process of galling, be- cause in moist weather, the astringent principle communicates a dark colour, and dries slowly. 5th. That the cotton ought to be pressed toge- ther with the greatest care, in order that the de- composition may be effected in an equal manner, at every point of the surface. 6th. That a pro- portion ought to be established between the gall- nuts and the soap ; if the former predominates, the colour will be dark, if the latter, a portion of the oil, not combined with the astringent princi- ple, will escape by the washings, and the colour will be poor. " The third mordant employed in dyeing cotton red, is the sulphate of alumine (alum). This substance not only has of itself, the property of heightening the red of madder, but it contributes alsOj by its decomposition, and the fixation of its alumine, to give solidity to the colour. To judge of the effects of alum in dyeing cotton, it will be sufficient to mix a decoction of gall-nuts with a solution of alum. The mixture becomes imme- diately turbid, and a greyish precipitate is soon formed, which, when dried, will prove to be in- soluble in water and the alkalies. Every thing that takes place in this experiment PERMANENT COLOURS. 26'£ of the laboratory, may be observed in the process of aluming, for dyeing. Cotton, when galled and plunged in a solution of the sulphate or acetite of alumine, immediately changes its colour and be- comes grey ; the bath presents no precipitate, be- cause the operation takes place in the tissue of the cloth itself, where the production remains fixed. But if the galled cotton be passed through a solution of alum that is too warm, a portion of the galls will escape from the tissue of the stuff, and a decom- position of the alum will take place in the bath it- self, which will diminish the proportion of the mordant, and impoverish the colour. " We have here, therefore, a combination of three principles (oil, the astringent principle, and alumine) which serve as a mordant for the red dye of madder. Each of them employed sepa- rately, produces neither the same fixation, nor the same lustre in the colour. " This mordant, undoubtedly, is the most com- plex of any which is known in dyeing ; and it pre- sents to chemists a sort of combination eminently deserving of their utmost attention. It is only from a great degree of precision in this combination, and a great portion of judgment in the artist who produces it, that a beautiful colour can be expect- ed j but though it be possible for him to conduct himself without error, through the labyrinth of these numerous operations, by taking the clue of experiment as his guide, he will find it very diffi- 270 PHILOSOPHY OF cult to simplify his progress, or bring it much nearer to perfection. It is only by reasoning on his operations, and calculating the result as well as the principle of each, that he can hope to become master of his processes, to correct their faults, and to obtain invariable products. Without this, the practice of the most experienced artist, will afford nothing in his hands, but the discouraging alter- native of success and disappointment. I wished, therefore, in this short analysis of the process for dyeing Turkey red, which is the most compli- cated of all, to give an instance of what che- mistry can do in the arts, when its principles are properly applied. I will venture to assert, that the most uninformed workman will here find the principle of his art, and the rule of his conduct." As I had long^ accustomed myself to respect the opinions of M. Chaptal, who, by being extensively engaged in dyeing the Turkey red, had obtained very superior opportunities of discovering the truth respecting it, and as his reasonings concerning the effects of the various applications under conside- ration, were so well calculated to produce convic- tion, I, without much hesitation, some years ago, adopted his general conclusion, that the result of all the operations for dyeing this colour, is that of producing a combination of three substances, alu- mine, oil, and the astringent principle (" Valumine, Vhuile, et leprincipe astringent"} and thus form- rng a mordant, which (in his ophiion) is the only. PERMANENT COLOURS. 271 one capable of rigorously Jibing the madder co- lour. See bis Memoir dans le Recueil des Me- moires dc l'institut, vol. ii. But after having adopted this conclusion, I was forced to believe, that a suitable, and perhaps more efficacious, combination of these three sub- stances, might be made with greater simplicity, ex- pedition, and benefit, than by the complicated, and, in many respects, incongruous mixtures and opera- tions commonly employed for that purpose ; and in this belief, I undertook, and was occupied, during almost all the year 180Q, by a series of experiments, in which oily, or saponaceous mixtures, decoc- tions of galls, and solutions of alum in e, were applied to cotton, with every possible inversion or change in the order of their successive applications, and with so many variations in their absolute, as well as relative proportions, and in all the circumstances likely to influence their effects, that, if it had been possible, by these means alone, to enable cotton to acquire from madder a colour equal to the Turkey red, it must, as I confidently believe, have been produced. The best results, however, of all my experiments were only reds ; not con- siderably better than those frequently given with madder by calico printers, in regard to their power of sustaining the action of soap, akalies, and the air ; though they were ablea little longer to resist the force of a diluted nitric acid ; a small immu- nity which was probably derived from the com- 272 PHILOSOPHY OF 1 bination of oil and the astringent matter of the galls with the alumine, which last is the only basis of the madder red given to printed calico. Since these failures, and in consequence of them, I have found it necessary to suppose, that some matter, hot to be obtained from oil, galls, and alum, is necessary to the stability of the Turkey red ; and this matter I have suspected to exist in the dung and the intestinal liquor of rumina- ting animals, or in that of their second stomachs, of which no use was made in my experiments, because they were not included by M. Chaptal among the things required to produce the Colour in question, and because M. Le Pileur d'Apligny,* M. Felix,! and others, had declared them to be of no use towards fixing the Turkey red.J At pp. 363 and 304 of my first volume, after * See Art de la Teinture des fils et Etoffes dc Coton. f See also his " Memoire sur la Teinture, & le Commerce du Coton file Rouge, dela Grece," in the Ann. de Chimie, torn. xxxi. + It must also be observed, that I did not employ either sheep's or ox's blood with the madder, in the' dyeing part of these experiments ; for though M. Chaptal believes that it may give more vivacity to the colour, he does not include it among the substances, contributing to its fixity, and I had it principally in view, to ascertain the matters necessary to produce that effect. Had I employed, and succeeded b) employing, Hood, my purpose would have been frustrated by reason of the various matters of which it consists, and which would have left me iri the same uncertainty as before. PERMANENT COLOURS. 27l mentioning the use made by calico printers, of cow-dung, to remove the superfluous part of their aluminous mordant, I have said there was " reason to believe that the cow-dung, by the gastric juices, gelatine and albumen, which it contains, afforded a very beneficial impregnation to the printed ca- lico, of some animal matter, which, combining with the mordant, serves to bind it more strongly to the cotton, and afterwards to increase its at- traction for the colouring matter, like some of the animal impregnations which are so necessary for the Turkey red." This opinion had been adopted, after all my endeavours to produce the colour in question from oil, galls, and alum, had proved use- less ; and when I had formed the opinion which I retain (and which by his " Memoire, presente a l'Institut National" de France, appears also to be entertained by M. Vitalis,) that the gelatine con- tained in the dung of ruminating animals, or the albumen which it also affords in a much lar- ger proportion, or some other matter, derived from it, and probably from their blood, is essen- tially necessary to produce that fixity, as well as beauty of colour, for which the Turkey red is so much admired, though at present, we only know with certainty of this matter, and this colour, that both may be communicated by the successive ap- plications and operations which have been recent- ly described, but of the pa) 'ticular effect of either, we are in a great degree ignorant. vol. 11. T 274 PHILOSOPHY OF The first operation (" decreusage") in each of the several courses, is intended, and may be deemed sufficient, to remove from the cotton, every thing which could obstruct, either the appli- cation or combination of the several matters re- quired to produce the Turkey red j and, therefore, the end of all the subsequent operations ought to be, that of adding, or promoting the combination of something, required to enable the cotton to imbibe and permanently retain the colouring mat- ter of the madder ; but several of these operations must, as far as I can judge, produce a different effect, by dissolving and removing a considerable part of the matters antecedently applied by the other preceding operations : such, for instance, must be the effect of the salt steeps, consisting of solutions of soda, employed subsequently to those containing the dung, the saponaceous mixtures, and the decoction of galls ; and, therefore, unless these latter steeps were either hurtful, or excessive in their strength or quantities, it must be inferred, that the salt steeps would do harm by diminishing, at least, the benefits to be derived from the pre- vious application of the dung, oil, and galls. M. Chaptal supposes, as others, when reasoning on this subject, have done, that the only good purpose to be answered by combining soda with . the oil, (necessary for the Turkey red) is that of rendering the latter miscible with water. But is it necessary that the oil should be mixed with PERMANENT COLOURS. *75 water ? If it be employed in sufficient quantity it will, while unmixed, penetrate the cotton as tho- roughly and equally, as it does when formed into the saponaceous mixture, and, perhaps, more so ; and though I once imagined that cotton, which had imbibed pure olive oil, so as to be saturated therewith, might not afterwards freely admit the astringent matter of galls, or the alumine ; or that the oil would afterwards obstruct '. v ! ; cation of the colouring matter, in the dyeing process, I have found, by repeated experiments, 'hat no such effect is produced by oil so imbibed; but, on the con- trary, that oil attracts and uniteswith the colouring matter of madder, and that cotton, even when the aluminous mordant has been first applied to it in spots, as by calico printing, may be soaked repeatedly in pure olive oil, and being merely squeezed to separate the superfluous part of the latter, it may be put into a dyeing vessel with madder, and there made to receive the colour most freely and copiously upon the spots or parts which had been previously alumed ; the attrac- tion of the aluminous basis for the madder colours, being rather promoted than lessened by this interposition of the oil ; though it must be confessed that the latter did not appear to ren- der the colour much more durable than it would otherwise have been. This being the case; the only reasonable motive for mixing the oil with water, must depend upon a belief, that while t 2 276 PHILOSOPHY OF unmixed it cannot be applied equally and tho- roughly, without being applied in excess ; but in opposition to this belief, I may adduce the practice of the Armenians, at Astracan, who, for their red dye, as we are informed by professor Pallas, soak their cotton in pure unmixed jisli oil, during seven successive nights, taking it out of the oil and exposing it to the sun and air, during each succeeding day ; and then, after rincing it only in running water, immerse the cotton in a steep or decoction of galls and the leaves of sumach ; then dry, and afterwards alum it, for the subse- quent operation of dyeing with madder.* These facts seem at least to render it probable, that the union of an alkali with oil is not necessary, to obviate the application of it too copiously ; and that if it be intended to remain in combination with * M. Bourdier, a physician, who had resided eleven years at Pondicherry and other places along the coast of Coromandel, asserts, that at Masulipatam and Pvlicat, (where the reds are excellent) the cotton, after being dyed, is soaked either in the oil of sesaraum, or in melted hogs' lard ; and the oil being afterwards pressed as much as it can be from the cotton, the latter is exposed to the sun and air for some days ; that this ope- ration it. repeated three times, after which the cotton is well washed. He sayr, that hegs' lard is preferred to oil for this use, and that the fine red handkerchiefs of Pulicat and Masulipatam have all been so treated. See " Mem. Geographiques, Phy- siques, &c. surl'Asie, l'Afiique, et l'Amerique," torn, 1. Pp. 207, 208. PERMANENT COLOURS. 277 the cotton, such an union, by rendering it mis- cible with water, must counteract that intention, and make the oil liable to be, in a great degree, removed by some, at least, of the subsequent steeps. That so much of uncertainty and obscurity should still prevail, in regard to this very estima- ble and extraordinary colour, is to me a matter of deep regret ; and if my life should be pro- longed a few years, and I should be enabled to choose my occupations, no endeavours of mine will be wanting to elucidate the subject ; being persuaded, that by doing so, I may not only enable the Turkey red dyers to produce their colour at much less expence, but that this elucida- tion will throw a most beneficial light upon other parts of the art, and afford means also of adding to the beauty and stability of many other co- lours. I have thought it expedient in this manner to endeavour to correct an error, which has lately become prevalent, I mean that of supposing that the true principle or cause of the fixity of the Turkey red had been discovered or ascertained , as this error must necessarily obstruct the attain ment of truth, by leaving no motive for subse- quent inquiries, or experiments, on this subject, 278 PHILOSOPHY OF ART. III. Rubia MajrHi, or Manjifha, of the Hindoos ; and Majishtlia of the Sanscrit, This species of madder was imported, though I believe in a small quantity, by the French East India Company, about the year 1760, under the name mongister ; and sometime afterwards, by the English East India Company, under the name of majesto root. More recently the im- portations into Great Britain have increased, and it has acquired, in the Company's sale catalogues, the names of mmjit, and mungeet. It has ap- peared to consist of the stem of the plant, com- monly six, eight, or more feet in length, and of twice the diameter of a goose quill, continued from the upper part of the root, (an inch or two in length, and commonly twice as big as the stem) bent into a form somewhat circular, and injudici- ously formed into loose bundles, occupying unne- cessarily much space, and consequently, incurring a great and needless expence for freight. Both the root and stem, when broken, appear inter- nally of a reddish colour, like that of madder. Wishing to obtain some more accurate informa- tion concerning this plant, than I had been able to procure, I questioned Dr. Roxburgh on the subject, previous to his last embarkation for PERMANENT COLOURS. 279 India, and was assured by him, that it was un- questionably a species of rubia, or madder; and that it, in his opinion, might very properly be distinguished, by giving it as a trivial or specific name the Hindu appellation of manjit'h ; which I have accordingly done ; as I find Dr. Fleming, on the same authority, has also done in his valuable account of East Indian drugs, (printed in the 11th volume of the Asiatic Transactions, 4to) where he observes, that this species of madder is indigenous in Nepal, and is used by dyers and calico printers, in the same manner as the rubia tinctorum is in Europe. Dr. Roxburgh represented this to me as a creeping or climbing plant, and the stem as spreading or rising to a great extent ; and he added, that unlike the stem of the rubia ■tinctorum, this of the manjit'h seemed to be pre- ferred to the roots for dyeing ; a circumstance which might be expected to render it a very cheap dyeing drug. From the results of a great number of experi- ments, I conclude the colouring matter of this species of madder, in its general properties, to resemble very nearly that of the rubia tinctorum, but with this disadvantage, that on cotton and linen, its red is not so durable as that of the latter, though in calico printing it gives much less stain to the white grounds, and, therefore,requires much less branning, and exposure on the grass. On the other hand, I find its red colour to be more bright 2S0 PHILOSOPHY OF and lively upon wool or woollen cloth when dyed with it, than that of the Dutch madder, and nearly, perhaps quite, as permanent j especially when solutions of tin are employed as the mor- dant. With these and the rubia manjit'h, I have repeatedly given to broad-cloth a scarlet, which, seen by itself, might be supposed to have been dyed from cochineal, though when con- trasted and compared with cochineal scarlets, a difference obviously presented itself, not in the vivacity of these colours, but in a greater incli- nation to the yellow tint, in those dyed from the manjit'h. This latter defect may, however, be easily removed, by employing a portion of cochi- neal with the manjit'h ; and by this mixture good scarlets might be produced with a consider- able diminution of expence. 1 have in the former volume, recommended such a mixture of cochi- neal with Dutch crop madder ; but the manjit'h is, I think, greatly preferable for this purpose. In regard to the durability of colours, given by the latter to cloth, with the basis of tin. I have ascertained, by sufficient trials, that it is fully emal to that of the cochineal scarlet. But on co:ton this basis produced no more stability of colour from the manjit'h than it does from cochineal, though I employed it with a variety of auxiliary matters, such as galls, glue, oil, &c. Some /ery pretty reds have, within a few years, been given to muslins from this vegetable with an abmi- PERMANENT COLOURS. 281 nous basis, and some addition, which is, I believe, a secret. With iron and other metallic bases, this vege- table produces colours differing but little from those given by the same means, with Dutch madder. After this statement, it will not be thought extraordinary that I should strongly recommend an increased importation of this dyen.g drug, es- pecially for the dyeing of woollen cloths, to which it has not, I believe, been hitherto applied, except in my own experiments on a small scale, though it certainly is preferable to Dutch madder for this purpose ; and by grinding, and close compression in casks, or other packages, capable of excluding moisture, the expence of freight might be lessened more than one half, without any danger of injuring the quality of the man- jk'h. There is another species of madder commonly used in China and Japan for dyeing, viz. the ru- bia cordifolia, described by Thunberg, (Jap. GO.) but I have had no opportunity of making any experiment with it. 282 PHILOSOPHY OF CHAP. IV. Of Vegetables affording Red Colouring Matters, nearly similar to that of Madder. *'• Most of those useful arts, and admirable inventions, which are the very support of mankind, and supply them with all the necessaries and conveniences of life, have at first been the production of some hieky chance, or from slight and contemptible beginnings, have been, by long experience, curious observations, and various im- provements, matured, and brought to perfection." Bishop Pqiter's Archeology Gr.sxa, vol. ii. p. 1?0. 3d edition. ART. I. Oldenlandiaumbellata. Umbclled Oldenlandia of Roxburgh. The Che or Chay, Chayaver, or Saya-ver, and Imburel of the Tamuls ; and Tsheri-vello of the Telingas. This plant, like madder, belongs to the natural order of stellatae, and its roots are universally, perhaps exclusively, employed along the coast of Coromandel, and that of Malabar, to afford the durable reds for which the cotton yarn, and chintzes of those parts of India, have long been greatly esteemed. Dr. Roxburgh, in his accurate and splendid work v on the plants of Coromandel, describes this as being a small biennial, rarely triennial plant, PERMANENT COLOURS. 283 growing spontaneously in very light dry sandy- ground near the sea;* and as being moreover extensively cultivated, especially on the coast of Coromandel. — The cultivated roots are very slen- der, and from one to two feet in length, with a few lateral fibres ; but the wild are shorter, and supposed to yield one-fourth part more of colouring matter, and of a better quality ; and this resides almost entirely in the bark of the roots, which, when they have been recently ga- thered, is of an orange colour, and tinges the spittle yellow, though by being long kept, the roots become apparently colourless, or at most only retain a very pale straw colour. The roots gathered at the end of their second year's growth are considered as the best ; but the farmer does not find it profitable to let them continue in the crround after the first. I have mentioned at p. 350 of my first volume, the employment of these roots by the natives of Coromandel, &c. for calico printing, or rather chintz painting ; but they require to be more * Dr. James Anderson, late Physician-general to the East India Company, at Madras, in certain printed letters to Sir Joseph Banks, asserts that these roots " will only yield colour when cultivated on the sea coast:" whether they derive any thing useful from the vicinity of the ocean, excepting a loose sandy soil, I know not. The roots produced in stiff clayey ground, are said to be of little or no value. 284 PHILOSOPHY OF particularly noticed, in regard to the use which is there made of them in dyeing that beautiful and lasting red colour upon cotton, which seems to have preceded, and can only be equalled by the Turkey red ; and by comparing the means and operations employed to produce these colours, it will be found, that those which afford the Turkey red, must have been suggested, at least, by a know- ledge of those antecedently employed with the che or chay root. It is remarkable, that though, (as was formerly mentioned,) an aluminous basis is prescribed and employed for the colour of this root, by all the instructions respecting its use in calico printing, and though a similar basis is particularly required for the reds dyed with it, upon calico, when no oil is employed, yet no mention is made of any such hosts, in the accounts given by Father Cocur- doux and others, of the means employed by the dyers in Coromandel, and Malabar, to produce that colour which is analogous to the Turkey red. In these accounts they arc said to form a mixture similar to the grey steep (or bain bis) lately described, excepting that instead of soda, they employ a lye of wood, or other vegetable ashes, and instead of Gallipoli oil, that of gingelly or sessamum, which is rendered milky, by com- bining it with the alkaline lixivium ; and to this they add either goat's or sheep's dung, which being dissolved, and equally dispersed through the PERMANENT COLOURS. 285 mixture, they steep therein the cotton yarn, (pre- viously cleansed by repeated macerations in water, and dryings in the sun) during nine or ten successive nights ; taking it out every morn- ing, and spreading it widely to the sun's rays, during the day ; after which the yarn is well rinced and dryed. This being done, instead of galling, as in the Turkey red process, a cold in- fusion is prepared from the powdered leaves of the memccylon capitellatum,* commonly called cassa, or cacha leaves, (which have an astringent taste) and in this the cotton is steeped once or twice, and dried after each steeping ; by which it acquires a full deep yellow colour. After this it is macerated in another cold infusion of the bark of the roots of the nana, or nona tree, (which appears to be a species of guilandina) and afterwards dryed. But though in most places, these infusions are applied separately, they are mixed in some -, particularly at Masuli- patam. By these macerations, and subsequent dryings, and without the mention of any aluminous or other basis, the cotton is said to be prepared for the dyeing operations, to be described here- after. * Dr. Roxburgh describes this as, being, in* general, x shrub, though sometimes growing to the size of a large tree. It is the Calamsaly of the Malabars, and allie of the Gentoos. 28G PHILOSOPHY OF The Abbe Mazeas having made himself ac- quainted with the accounts of these operations, as given in the 26th and 27th " Recueil des lettres Edefiantes," and in certain manuscript relations, some of which were procured by M. du Fay and others, furnished by M. de Rabee, (who had then lately returned to France from India) and being persuaded, that in reality no aluminous bash was employed, to produce the red colour under consi- deration, (because no mention was made thereof in either of these accounts or relations) he assiduously occupied himself with this subject, and endeavoured not only to produce a similar colour without the aluminous basis, but to discover and explain the principle or philosophy of an effect, so extraor- dinary. He was perfectly aware that an alumi- nous basis had been constantly employed both in Turkey and France for the Turkey red, and that all the dyers of that colour firmly believed, that it could not be produced without that basis ; bat he considered this as an erroneous opinion, and en- deavoured to account for its existence, by sup- posing, that the Turks, after being informed of the East Indian process, must have failed in their attempts to carry it into practice, and that after this failure, they had with more success resorted to the means employed by Europeans for dyeing thread and yarn ; I mean those of aluminp and galling ; which had thus been unnecessarily su- peradded to those employed on the coast of Mala- PERMANENT COLOURS. 287 bar and Coromandel. It appears from his memoir, intitled " Recherches sur la cause Physique, de I'adherence de la co'uleur Rouge aux toiles peintes, qui nons vient des cotes de Malabar & de Coro- mandel," and from his Appendix to that Me- moir, (printed among the " Memoirs de Mathe- matique et de Physique," presented to the Royal Academy of Sciences at Paris, " par divers Savans," torn, iv.j that all his endeavours to produce the desired colour without an alumi- nous basis, were unavailing, until he had sub- stituted hog's lard for the vegetable oil commonly employed ; but that with this substitution, he suc- ceeded in dyeing one small hank or skein of cotton yarn, ("un petit echeveau de coton,")with a red colour which supported boiling with soap, (" qui a resiste au de bouilli du savon ;*) and consider- ing this as a sufficient evidence of the practicability of producing the desired colour, without any alumi- nous basis, he proceeds to reason upon, and ex- plain, the supposed fact, without any discoverable attempt to establish or confirm it by a second ex- periment, though from its most extraordinary and incredible result, he ought to have consider- ed several repetitions of his experiment, and with * He does not say how long it did this. It might have been for even less time than the common madder red will bear this trial. 288 PHILOSOPHY OF constant success, as being necessary to convince others, that he was neither deceived himself, nor been inclined to deceive. But the philosophers*of that time (1774) appear to have been so indulgent, that no one publicly questioned this supposed fact, and the Abbe's explanations concerning it, were received in different parts of Europe, with great applause, and have been since deemed an adequate foundation for various theoretical notions of the practicability and utility of imparting to linen and cotton, a certain animalization, to enable them to imbibe and retain colouring matters, more copi- ously and permanently than they could other- wise do.* * The following are the Abbe s principal reasonings and conclusions from his experiment, viz. " II suit de la, que les huiles animales sont plus propres a reoperation, que celles que nous tirons des vegetaux en Europe ; mais par quel mechanisme* ces huiles retiennent — elles les parties imperceptibles, qui, dans les excremens animaux, se joignent aux atomes colo- rans de la garance ? II est d'autant plus difficile de l'expliquer, qu'on ne remarque aucune difference sur les fibres, quiont ete empreintes du savon, tel que je vieus de Ie decrire, soit que Ton supprime ou non, les excremens animaux. Cependant cette suppression fait une grande difference pour la couleur, car le coton ne la prend pas, toutes les fois que Ton emploie le sain-doux, sans employer les crottes de brebis ; preuve cvi- dente que les graisses des animaux, ne coniiennent point les molecules, avec les quelles la garance a tant d'affinite. * Every thing at that time was to be explained upon mechanical principle*. PERMANENT COLOURS. 289 It will have been seen, by the opinions which I have delivered on this subject in the preceding chapter, that I am not disposed to deny the effi- cacy of some animal matters toward enabling linen and cotton to acquire more durable colours in dyeing, than any which we as yet know how to communicate, without them ; but this, so far as my experience reaches, is done by some peculiar pro- perty, besides that of their animal nature, and only in conjunction with some earthy or metallic basis. Indeed, numerous experiments have convinced me, that if it were practicable, by the application of such matters completely to change the nature of linen and cotton, and give them not only the chemical properties or affinities of wool, but also " S'il m' etoit permis de me livrer £ des conjectures, je croirois que toute l'operation se reduit, a" depouiller le sain- doux qui s'est joint aux molecules excrementielles, de toute sa partie grasse, et qu'il ne reste plus sur les fibres du coton, que la partie terreuse de cett^e graisse, indissoluble aux alkalis savon- neux: mais il est bien difficile de s'en assurer par l'expdr ence j ici la nature disparoit a nog yeux, ou plutot elle se voile sous un mechanisme si delicat, qu'a peine laisse-telle quelque prise a l'imagination. " Je me borne done au fait que je viens d'etablir." " L'essentielle, avant d'aller plus loin, etoit de constater te principe, et de faire voir que dans cettc espece de tilnture, les atomes colorans se jettent immediatement sur la substance animate, el non sur la terre blanche d'alun, comme il arive dans la teinture d'Andrinople." See p. 21 and 22 of the volume recently quoted. VOL. II. U 290 PHILOSOPHY OF the advantage of its porous and tubulous struc- ture, it would still be impossible to make it capable of acquiring, either from madder or the chay root, a colour like that in question, without the aid of some basis or means beyond those stated to have been employed by the Abbe Mazeas in his suc- cessful experiment : I have, indeed, repeated that experiment, and made others upon similar prin- ciples without success, and I have, therefore, but little difficulty in believing, that in regard to the results of that experiment, he must have been deceived ; probably by supposing, unwarrantably, that his colour possessed a much greater degree of stability, than it could have done without other means. But what are we to think of those who, more recently as well as formerly, have, in their communications, omitted to mention the employ- ment of any preparation of alum in dyeing the Malabar and Coromandel red upon cotton yarn, from the chay root ? Did this omission proceed from ignorance* and inattention in the authors of these communications, or from studied concealment in the Indian dyers ; or is it more probable that the water employed by them may naturally hold alum * When persons do not understand the principle, or cause upon which the success of an operation depends, it must al- ways be difficult for them to describe it completely, or without overlooking something of importance. PERMANENT COLOURS *9i in solution, and that this fact may have been over- looked, by persons who were not properly sensi- ble of its importance ?* That the colouring mat- ter of the chay root does not possess any peculiar property, which could enable it, without alu- mine, to produce effects which the dyers of Tur- key red have found it impossible to obtain from madder without that basis, I am well convinced by a multitude of trials ; I have, indeed, found that when cotton had been fully impregnated with oil, the soluble parts of sheep's dung and of gall nuts, its attraction for the colouring mat- ters both of madder and of chay roots, was con- siderably increased, but not in any degree which could at all warrant a belief of its being practicable, by such means only, to produce any colour similar to the Turkey red, and yet, in addition to the omissions in the several accounts already noticed, I have to observe, that there is no mention of alum in the communication lately made to the Society of Arts, Manufactures, &c. by Mr. Machlachlan, of the process for " dyeing the beautiful reds of the Coromandel Coast, from chaya root, and the f Dr. Taylor, Secretary to the Society of Arts, Manufactures, and Commerce, who possesses great theoretical and practical knowledge on the subject of dyeing, and was formerly engaged extensively in the dyeing of Turkey red, told me very lately, that the last of these suppositions appeared to him to be the most probable. V 2 292 PHILOSOPHY OF leaves of cashaw, or cashan ;" (see the 22nd vo- lume of their Transactions,) nor in that which was recently made by Mr. Benjamin Heyne, act- ing Company's Botanist on the Coast of Coro- mandel, (in a letter) to the Right Hon. Lord Ho- bart, (now Earl of Buckinghamshire) of the me- thod used by the Malabars, of dyeing a beautiful and lasting red on cotton yarn, with the chay root, &c. of which I was favoured with a copy by Dr. Roxburgh. This communication by Mr. Heyne, would probably have obtained a greater portion of my confidence, if he had appeared either to have known more, or not to have known so much, on the subject ; and especially if he had not been so manifestly influenced by the reasonings of Mr. Gren in regard to the supposed animalization of the cotton dyed by this method ; to which ani- malization he exclusively imputes the stability of this colour, and seems to believe (erroneously) that the first notions of its utility originated with Mr= Gren, It appears, by Mr. Heyne's account of the Ma- labar practice, that the cotton yarn is divided into small skeins of only 30 or 40 threads each, and so attached to bamboo sticks, that, when spread, every single thread may be exposed to the pow- erful rays of the sun ; after which, being put into cold water, it is beat and pressed by hands, du- ring half an hour, and then left to steep until it PERMANENT COLOURS. 293 begins to emit a putrid smell, which it will com- monly do in that climate at the end of 36 hours ; when this happens, the yarn is well washed, then beaten upon a stone, and afterwards exposed to the sun. Mr. Heyne supposes, that the former part of this operation may separate some muci- laginous, gummy, or other vegetable matter, which might obstruct the action or combination of the other matters which are to be subsequently ap- plied and that by the subsequent beating, the tex- ture or twistings of the threads must be so loosened as to render each fibre more accessible to these matters. The next application, and the only one contain- ing animal matter, resembles the grey steep, or bam bis, already described; excepting the substi- tution of a lixivium from the ashes of burnt vegetables, for that of soda, and of the gingelly oil* for that of Gallipoli, and, excepting an addition which is made to it, of a liquor called zickey, to be soon described. Mr. Heyne computes that for each pound of yarn, it may be necessary to employ in this steep one pint of oil, two quarts of lye, and half a pint of zickey, with five * Mr. Heyne says, the Malabar name of the sesamum orientale, which affords the gingelly oil, iselloo, and the Gen- too name, noovoo-chittoo j and that the dyera never use it until, by keeping it a year or longer, it becomes rancid, and of a yellow colour. .294 PHILOSOPHY OF or six ounces of sheep's dung. When this mix- ture is made, the yarn is to be soaked and squeezed in it, for half an hour, then spread out, two or three hours, to dry in the sun ; then soaked, and squeezed again, and afterwards spread out to dry, in the same manner, and finally soaked, squeezed, and dried a third time, all in the same day ; after which, the cotton is to be put back into the steep, and left to macerate during the night; and in the morning, the three soakings, squeezings, and dryings, of the preceding day, are to be repeated, and at night the cotton is to be again macerated, &c. which treatment is to be continued during ten days ; it is, indeed, prolonged by some of the dyers, with a few slight alterations, for a longer term. When the cotton is supposed to have im- bibed a sufficient portion of this, which Mr. Heyne considers as being an annualizing mixture, though it contains nothing of an animal nature but the dung pf sheep feeding on vegetables, it is to be washed jn clean water ; and the matters separated from it by this washing, are to be preserved (with the water employed in the washing) for the space of a year, or until the liquor has acquired some de- gree of ropiness with a putrid smell, when it takes the name of zickey, and is employed, as be- fore mentioned. ♦After this treatment, the cotton is to be tho- roughly wetted, by repeated dippings and squeez- ings in water, rendered almost as thick as paste, PERMANENT COLOURS. 295 by a previous admixture of the powdered casa, or casha leaves,* lately mentioned, and afterwards left to soak in this mixture during the night, and being rinced the next morning, it is to be dried in the sun, and afterwards soaked during one night in an aqueous infusion, made with two hand- fuls of powdered chay roots, and two handfuls of the leaves of the same plant, for each pound of the yarn, and dried in the sun the following day ; which soaking and drying is to be repeated the two following nights and days. But on the fourth night, the soaking is to take place in an infusion of the chay roots, without the leaves : On the fifth day, some of the powdered casa leaves are to be formed into a paste, by rubbing them with gingelly oil, and this paste is to be mixed with a quantity of powdered chay root in water, and in this the yarn is to be soaked during the night, and dried in the sun the following day : and this soaking and drying is to be repeated three suc- cessive nights and days ; after which the yarn is to be dyed by putting it into warm water, with a sufficient quantity of powdered chay root, and * Mr. Heyne says, these dyers will never make use of the leaves growing near their own habitations, even though (as sometimes happens) they are obliged to pay unreasonably for those brought from distant situations ; and he appears to think there is a considerable difference between the leaves produced on the sea coast and those of more elevated districts. 296 PHILOSOPHY OF bringing it gradually to a boiling heat, which is to be continued until the yarn is supposed to have acquired sufficient colour. But if the dyer after- wards thinks it defective, the cotton is again to be soaked in a cold infusion of casa leaves and chay root, powdered, and again boiled with the latter. This tedious process, of which I have given an account in as few 'words as possible, occupies al- most a month, and is said to be also practised, with some unimportant variations, along the Coast of Coromandel, from Cape Comorin to Pallia- cottah, but to be unknown in the northern Circars, and in Bengal. The colour, though not very bright atjirst, because its superfluous and brown- ish parts are not separated by a brightening process, (as they are in the Turkey red) con- stantly improves by wearing and washing. It will hare been observed, that no blood is used in dyeing this colour, and that the cotton imbibes a great proportion of its red colouring matter by being repeatedly soaked in the cold infusions of powdered chay root.' The subsequent boiling with more of that root, while it supplies additional colouring matter, probably unites or combines that which had been previously applied more firm- ly, by giving greater force and energy to the attrac- tions of the several matters which are intended to co-operate in producing and fixing the colour ; and of these, I am convinced, that alumine, applied in some way or other, must be one, though Mr. PERMANENT COLOURS. 297 Heyne, (who appears to have seen most of the ope- rations described by himself) distinctly asserts, that any such addition would be, not only useless, but injurious to the beauty, at least, of the colour; an assertion which I know not how to believe, considering that the Turkey red, dyed upon the aluminous basis, is at least equal to that of Malabar in beauty and permanency. This I know by a skein of very fine Malabar red cotton yarn, which I received from Dr. Roxburgh, and which T have compared and tried in various ways with samples of the best Turkey red, dyed in Great Britain and France. I am, indeed, the more disposed to consider Mr. Heyne's communication as defective in regard to the use of alum, because I find the latter men- tioned as equivalent to, and capable of being substituted for the cassa, or allie leaves, in a manuscript account given by Mr. Ram, " of the method of dyeing red with the chay root in the Guntoor circar ;" which manuscript was also put into my hands by Dr. Roxburgh. From this ac- count it appears, that the cotton, after being treat- ed nearly as Mr. Heyne has described, until it is supposed to have sufficiently imbibed the matters imparted by the grey steep, (composed of an alkaline lixivium, gingelly oil, sheep or goat's dung, and zickey) is to be washed in clean tank water, and well dried ; and then " half a pucca seer of the powder of allie (cassa) leaves, or two 298 PHILOSOPHY OF dubs weight of alum" are directed to be put, with a suitable quantity of water, to the cotton : but as the properties of the allie leaves, are so very dissimilar to those of alum, that one cannot be sup- posed to produce the effects, or answer instead of the other, I think it most probable that Mr. Ram's account would have been more correct, and con- formable to the practice of the dyers of the Gun. toor Circar, if he had mentioned the alum as being employed, not instead of the allie leaves, but subsequently to them ; which, considering their astringent property, would have been similar to the practice of the Turkey red dyers, who employ the alum steep immediately after that of galls. A large quantity of chay root was brought to this country about ten years ago, on account of the East India Company. Until this importa- tion, my only experiments with this root had been made upon a small parcel which grew in the garden of the late Mr. East, at Jamaica, and which, from some defect (as I supposed) in the soil, or situation where it was produced, afforded me but very little colouring matter. In consequence, however, of this importation by the India Company, I was abundantly supplied, and through different channels, with chay root for my experiments ; but though some parcels of it were better than others, none of them produced effects equal to the expectations which PERMANENT COLOURS. 299 I had formed in regard to the properties of this root ; and I found, albO,that of the several dyers and calico printers, to whom samples of it had been sent, no one had succeeded with, or was dis- posed to adopt the use of it. This want of suc- cess led me to suspect that the imported roots had either been defective in quality when shipped, or had afterwards suffered injury, by age, or, more probably, by the warmth and humidity of the places in which they were stowed to be brought to Europe ; and this suspicion was afterwards con- firmed, by comparing the results of my experi- ments and examinations with the rules and marks for distinguishing the good from the defective roots, which had been mentioned by Mr. Heyne, in his letter to Lord Hobart.* * Mr. Heyne in this letter, after describing the chay root as being not less important for dyeing and calico printing in that part of India, than madder is in Europe, observes, that great care is necessary to ascertain that it is of good quality, and has not been injured by exposure to rain, or by being kept in damp situations : of such injury, says he, " a certain sign is, that a white colour prevails on the inside of the hark, and in its woody pari ; as, on the contrary, a green colour may be taken for the surest sign of its being good." He adds, that the Malabar dyers, in order to ascertain whether the chay roots have been well preserved, mix some of their powder with a little quick lime in water, and if it affords a fine bright red, they deem it to be good j but the contrary, if the colour be only a brownish or dull red. That the natives keep the roots with their sterna together in large bundle*, secluded from rain and damp air; WJ PHILOSOPHY OF But having long be^n anxious to ascertain the properties of a dyeing drug so much celebrated as the chay root, I endeavoured to procure for my experiments some of that which had suffered the least of any in the parcels imported by the India Company, which I was the better able to do, because the greater part of that importation had fallen into the hands of one of my particular friends ; and I afterwards bestowed no small por- tion of my time and attention in making what appeared to be the most proper trials therewith : and by these I satisfied myself that the red colour produced by the chay root, in combination with an aluminous basis, not only on wool, but on linen and cotton, resembledvery nearly, in its appearance and permanency, that given by madder with the same basis. It did not seem in any instance to excel that of madder, and sometimes appeared Jess beautiful, and less durable; but this diffe- rence when it occurred, might, as I thought, be reasonably attributed to the injury which the chay root had probably suffered in its quality. When applied to calico 'printed with acetite of alumine, the effect was much like that of madder, except* ing that the white grounds were less stained. and avoid pounding the roots until they are wanted for immedi- ate use. Then they are carefully separated from the stalks, theiv small fibres cut off, and the better parts of the roots farther dried, to facilitate their reduction to powder. PERMANENT COLOURS. 301 With the solutions of tin, the chay root pro- duced a very bright and lasting red on wool; though, like that of madder, it inclined a little too much to the orange ; galls employed with the chay root in dyeing wool, made the colour incline still more to the yellow, as well on the tin as the aluminous basis. The most remarkable difference in the colouring matters of these roots, was that which regarded their effects with the solutions or oxides of iron, which, with chay root, produced nothing darker than drab colours , either upon wool or cotton. Woollen cloth boiled with a solution of lapis calaminaris (oxide of zinc) with muriatic acid, and dyed with powdered chay root, took a bright apple green ; and, by substituting a diluted nitrate of lead, as the mordant, a bright cinna- mon colour was obtained from this root. By the Turkey red process, the colouring matter of the chay root produced effects so much like those of madder, that I was confirmed in my belief that the means of fixing its colour, as in the Malabar red, must be substantially the same as those employed with madder in Europe, for the Turkey red. Broad-cloth, dyed without any basis, obtained from chay root a brownish red, which was, certainly, neither so bright nor durable as that which it imbibes in the same way from mad der ; for, by a fortnight's exposure to the sun and air, even in winter, it was reduced to a buff colour : 302 PHILOSOPHY OF a strong indication o£ the necessity of an alumi- nous or other basis, to raise and fix the colour of chay root, even on a substance by its nature completely animal. In regard to future importations of the chay root to this country, I think they can never be adviseable. A large quantity of it was sent to France, about the year 1774, an account of the then French East India Company ; of which no beneficial use could be made, by any of those who attempted to employ it, probably, because it had been damaged, like that since imported to this country. It is true, that M. Le Goux de Flaix endeavours to account for this want of success, by supposing, most erroneously, that the pur- pose for which this root is employed in the East Indies, and the only one which it can an- swer, as he imagines, is not that of giving co- lour, but of fixing the colour of other matters there employed with it, in dyeing and calico printing. (See Annales des Arts et Manufactures, No. SI,) This error** however 3 as it rests on no evidence, and is contradicted by the best of testi- mony, as w r ell as by many known facts, does not deserve any farther notice : and I conclude from the defective quality of these several importations, that this root must be liable to injury from some cause, naturally, and perhaps, unavoidably connec- ted with a voyage from India to Europe. But if it were possible to obviate all injury of this sort, I should still believe, that no profit or benefit could PERMANENT COLOURS. 305 result from any future importation of chay root to Great Britain. It can produce no effect which may not be as well obtained from madder, and, as I think, more cheaply. The roots, though very small, consist of so great a portion of tough woody Jibres, yielding little or no colour, that as tar I can judge, two pounds thereof will not pro- ducemore effect than one of madder ; probably not so much ; and as it is most liable to be injured by moisture when reduced to powder, the unground roots can alone be imported, and those must oc- cupy so much space, as greatly to augment the ex- pence of freight ; and being, moreover, extremely hard and imigh, the cost of grinding a given weight of them will, at least, be double that of grinding an equal weight of madder roots, and consequently, must augment, in a four-fold degree, that part of the expence of employing this Indian production in Europe. ARTICLE II. Galium. This genius of plants 'belongs, like the preced- ing, to the natural order of Stellatse, and consists of forty eight welhascertained species, whose roots, with perhaps a few exceptions, contain a red colouring matter, very similar in its properties and effects to that of madder; though, when the brown external covering of the root has been S04 PHILOSOPHY OF completely separated, the colour which it gives to wool is certainly brighter than that of madder, at least upon the aluminous basis. The several species of the galium most esteemed and employed in dyeing, are, 1st Galium tinc- torium. This abounds in the woods of North America, and is called by the French inhabitants of Canada, tyssa voyane rouge, and employed by them to dye their cloths red, as it was by the abo- riginal Americans, to dye their porcupine-quills, &c. of that colour. I have made some experiments with two small parcels of this root, one of which was brought from Hudson's Bay, and the other from the country of the Cherokee Indians, (west- ward of Carolina) both of which communicated a very bright and lasting red colour to woollen cloth and to calico, with an aluminous basis, and with iron, colours resembling those of madder, upon the latter basis. Broad-cloth, prepared with the nitro-muriate of tin and cream of tartar, as for scarlet, and dyed with these roots, obtained a more lively red colour than that given by them wit h alum. The roots of this species of galium are of a dark reddish colour, and though nearly two feet in length, are very slender. These, if I do not mistake, are the roots mentioned by du Pratz, (in Jhis history of Louisiana) under the name of ache- chy, as being full of red juice like chicken's blood, PERMANENT COLOURS. 805 with which, says he, the tribes about the Mississippi give a beautiful red to their feathers, &c. The Transactions of the Agricultural Society of New York, contain, as I am informed, an experi- mental Essay on the properties of galium tincto- rium, its uses, &c. by Professor Woodhouse, which Essay, I have not been able to procure. 2d. Galium verum ; yellow ladies' bedstraw, or cheese renning. Dr. Cuthbert Gordon, about twenty five years ago, warmly solicited the attention of the Committee of Privy Council for Matters of Trade, &c. to the cultivation and use of this species of galium, not merely as a substitute for madder, but in some degree of cochineal also ; alleging that a scarlet colour might be produced from it, which in beauty would almost equal that of cochineal, and surpass it in durability : and, indeed, some specimens of the colour which I have now before me, and which were said by him to have been dyed from this root, are but little inferior to a great part of the scarlets commonly dyed with cochineal. Ur. Gordon, for his exertions on this subject, obtained a small remuneration, ("2001.) and some attempts were macj^by the Commit.ce of the Privy Council" to promote the cultivation of this plant ; but, I believe, they were not attend- ed with success, and probably the quantity of colouring matter which the roots afford, is not sufficient to compensate the expence of bringing them to a state of maturity, which requires at vol. II. x 306 PHILOSOPHY OF least four years. They are covered by a very dark skin or bark, which must be separated, that its brown colour may not injure that of the other part of the root. Like madder and chay root they rapidly absorb moisture, unless secluded from it, and suffer great injury by doing so, The flowering stems of this plant afford a yellow dye, though it is not much esteemed. According to Pennant, Lightfoot, and others, the roots of this species of galium are commonly employed by the people of the highlands, and of some of the islands of Scotland, particularly Jura and Ulot, for dyeing a bright red upon their woollen stuffs* Its eolouring matter is placed almost exclusively in the inner bark of the roots, and it seem& necessary to employ, at least, three times as much of them as of madder, to produce equal effect. If propagated for dyeing, it should be planted in a very deep loose sandy soil, having some inter- mixture of marl. Sd. Galium mollugo ; or great ladies' bedstraw, commonly called wild madder, and great bastard madder. Its roots are a little larger than those of the former species, and they produce, by dyeing, a red colour equally bright and lasting. 4th. Galium sylvaticum ; wood ladies' bedstraw : the rubia sylvatica levis of Bauhine. Its roots dye red, like the preceding. 5th. Galium boreale; cross-leaved ladies' bed- straw : rubia pratensis lsevis acu to folio of Bau- hine, Pinax 333. Permanent colours 307 I have made no trials of this root, which is Said to afford a more lively and beautiful red than the roots of any other species of galium. Haller says, that in Switzerland the roots are ground with the dust of malt, and afterwards infused in small beer, and that woollen yarn, being first macerated and afterwards boiled in this mixture, acquires a fine red colour : probably alum is employed at the same time ; though he does not mention it. 6th. Galium aparine ; common rough ladies' bedstraw ; cleavers, or goose grass. The roots of this species also dye red, but the colour is less pure and vivid than that of galium boreale : which is, also, the case of several other species of this ge- nus, particularly galium purpureum, or purple la- dies' bedstraw, andgaliumcruciatum, or crossword Most, and probably all, of the species of galium, before mentioned, impart (like madder) a red colour to the bones of animals, with whose food the powdered r oots have been mixed. Very nearly related to galium, and possessing a similar colouring matter, are the roots of seve- ral species of the genus asperula ; woodroof, or woodrowel, particularly asperula arvensis, blue or field wood roof, which Bauhine considered as a species of madder, and also, Asperula tinctoria ; or dyers' woodroof, the roots of which, according to Linnaeus, are used for dyeing red instead of madder, particularly bv the inhabitants of Gothland. x 2 308 PHILOSOPHY OF ART. III. Morinda Citrifolia, Lin. A Shrub, (sometimes ar- boreous) ; the Bancudus small latifolia ofRktim- phhis ; Coda-pilava of Rheede, and of Ray ; called Aal, in Malava, and Atchy, in Oude. This genus, like those of rubia, oldenlandia, and galium, is included among rubiacea: of Jussieu ; but it does not, like the others, appertain to the natural order of stellatre : and its colouring matter partakes so much of the orange, that it is only by being concentrated and accumulated in the stuffs dyed therewith, that it produces a red colour, always inclining a little to the orange tint. Indeed, one species of this genus, the morinda umbellata, is employed in Cochinchina, and other parts of Asia, as a yellow dye ; and the genus itself is so nearly related to that of morus, which contains the dyers* mulberry, (improperly called old fustic) that its name was thereby sug- gested to Vaillant, and composed from the words morus indica. The colouring matter of the morinda citrifolia, resides chiefly in the bark of the roots of this shrub ; and as the smaller branches, or divisions of the root, contain the least proportion of woody fibres, and, consequently, yield most colouring matter, they bear the highest price. PERMANENT COLOURS. 309 When Mr. Alderman Prinsep returned to this country from India, more than twenty years ago, he favoured me with a box filled with small roots, broken into a coarse powder, and in colour differing not much from madder : to this he gave the name of aurtch, adding, that it was " the Bengal substitute for madder -, and that, if better pounded, it would answer in the proportion of three to two of the latter." He gave me no in- formation concerning the ways or means of em- ploying this substitute in Bengal ; but I find in the Asiatic Researches, (vol. iv. p. 35. 4to.) a com- munication by Wm. Hunter, Esq. respecting this species of morinda, and the red colour dyed with it, in that part of India, from which, and several coroborating circumstances, I am con- vinced that the roots given to me by Mr. Prinsep are no other than those of morinda citrifolia.* I lately mentioned that the Malabar and Coro- mandel red dye from the chay root, was not known to the Bengal dyers ; and, so far as I can discover, they supply its place by that which is produced from the roots of this species of mo- rinda. By Mr. Hunter's account it appears, that the cotton to be dyed by these roots, is first mace- rated in a lixivium of soda mixed with the oil * Probably the name of aurtch, employed by Mr. Prinsep, has been derived from that of atchy, which the morinda citrifolia bears in the province of Ouds, ;iio PHILOSOPHY OF of sesamum, then rinced and dried. It is af- terwards soaked in an aqueous infusion of the large her, or har, (which is the ripe astringent fruit of the terminalia chebula, a species of my- robalan,) and, after the infusion has been mode- rately squeezed from it, the cotton is exposed to the rays of the sun during four or five days, in which it will acquire a cream colour. It is then macerated in a solution of alum, (made by em- ploying one pound of water, to each ounce of alum in powder,) and after being thoroughly and equally penetrated by this solution, the super- fluous part of the latter is to be separated by moderate pressure, and the cotton again exposed four or five days to the sun, that it may be well dried ; and this being done, it is rinced in cold water, and again dried. Three gallons and one half of water are then put into a copper dyeing pan, placed over a fire, and the cotton immersed therein, so that it may be equally and thoroughly wetted ; this being done, add from one to two seers of aal{\. e. the roots of morinda citrifolia,) in powder, (according to the quality of the powder,) having first rubbed and well mixed the latter with the oil of sesamum, at the rate of two ounces for each seer of the powdered roots. Put also into the pan, one eighth of a seer of the flowers of dliawry* for each seer of the aal ; or, instead of This vegetable is the lythrum fruticosum of Roxburgh. PERMANENT COLOURS. 311 these flowers, one ounce and one half of purwas, (a sort of gall nut,) in powder. The cotton and other ingredients, just mentioned, are to be kept over a very moderate fire during three hours, at the end of which, the liquor is made to boil until the colour is sufficiently- raised ; the cotton being constantly stirred, and frequently lifted above the dyeing liquor. If the latter becomes red, it is supposed that the colour of the cotton will be defective, unless a farther portion of the flowers of d'hawry be added. The red colour dyed in this way, is said by Mr. Hunter to be more es- teemed for its great durability than for its beauty. He adds, that with a basis or solution of iron, these roots dye lasting purple and chocolate colours j that they penetrate three or four feet into the earth ; that great quantities of them are sent to Guzerat and the Northern parts of Hin- dostan. Presuming that the roots which I received from Mr. Prinsep, as being the Bengal substitute for madder, must be those of the morinda citrifolia, I shall here mention the results of my experi- ments with them, in dyeing woollen and cotton stuffs. To the former, prepared as usual by being boiled with alum and tartar, these roots com- municated by dyeing in a moderate heat, as with madder, a bright red colour, inclining a little to the orange tint, which, by subsequent exposure 312 THILOSOPHY OF to the sun, rain, winds, &c. proved to be very durable. Broad-cloth prepared by being boiled with nitro-muriate of tin and tartar, as for the cochi- neal scarlet, acquired a very bright colour, but little inferior in vivacity to the colour which would have been produced, if the cloth so pre- pared had been dyed with cochineal, but par- taking too much of the orange to be deemed a scarlet. Indeed, it very much resembled the colour which I lately described as having been produced by the rubia manjit'h upon cloth pre- pared in the same way; and this colour was also found to be very durable. Calico, printed with the acetates of alumine and of iron, both separately and mixed, being afterwards cleansed as usual, and dyed with the Bengal substitute, took red, purple, and darker colours, very much like those which would have been produced by madder with the same bases or mordants, and equally durable. "With other bases, colours were produced not differing much from those which madder would have produced with the same means. And I am, therefore, induced to believe, that importations of this rpot, to be employed here instead of madder, might afford profit to the importers, and benefit to the public. There is certainly no danger of its suf- fering like the chay root, either by a sea voyage, or by long keeping in this country, at least if PERMANENT COLOURS. 313 proper care be taken of it ; the parcel given to me by Mr. Prinsep having now been more than twenty years in my possession, without any per- ceptible deterioration, though powdered, and never secluded from atmospheric air, even when the latter was unusually damp. Care should, how- ever, be taken previously to bring these roots into a state, in which they will occupy the least possible space, and be liable to the least expence for freight &c. I may be here allowed, as I hope, slightly to notice a few other red colouring matters, which, though they do not strictly appertain to this chapter, cannot be referred to in any other, with- out greater impropriety. Of these, the first is the anchusa tinctoria, or dyers' alkanet ; the root of which abounds in a dark red colouring matter, readily soluble in alcohol and in oils. It was employed to dye wool by the ancients, as is mentioned by Pliny, Lib. xxii. c. 10. and has been used for the same purpose by the moderns, particularly in France, though the use of it in this way seems to be now generally discarded, that of madder being found much more advantageous. Haussman, indeed, states, in the Ann. de Chimie, torn. 60, that if the colour of this root be extracted by alcohol, and applied by dyeing to silk or cotton which have previously imbibed the aluminous basis, it will communicate a beautiful and sufficiently perma- 314 PHILOSOPHY OF nent purple violet colour, (pourpre-violet 3 ) but this menstruum would be too costly in this country. The roots of the anchusa virginica, called puccoon in that part of America, possess a colouring matter nearly similar, and were for- merly employed by the savages to paint their naked bodies. The roots of the sanguinaria canadensis, or Canadian blood root, so called by Mori nus, and after him by Dillenius, from the blood-red co- lour, which the juice of the fresh-gathered root exhibits, (but which changes to an orange by drying,) are sometimes employed by the inha- bitants of South Carolina for giving an orange colour to silk and muslins, though it soon fades, and was found, by many experiments which I made with it, incapable of being rendered per- manent. This seems, also, to have been called puccoon by the savages there, and was, as is mentioned by Catesby, employed with bear's oil to paint their skins. With a solution of tin it produced a bright orange on silk. It possesses a violent emetic quality. I received, some years ago, from Dr. Rox- burgh, a small parcel of the red powder, which covers the capsules of the rottleria tinctoria, or wassunta-gunda of the telingas, which powder is a noted dyeing drug, especially among the Moors in the East Indies, and forms a consider- able branch of commerce from the mountainous PERMANENT COLOURS. 315 irts of the Circars. The colour of this powder seems to be intermixed with a portion of resinous niatter, which renders it but little soluble in water only, but being made soluble by an ad- mixture of soda, I found it afterwards capable of dyeing a very high and bright orange, with alum and with the solutions of tin, which orange colour was sufficiently durable on silk, but less so on cotton. > Barrere, in his Nouvclle relation de la France Equinoctiale, p. 39, mentions a species of convol- vulus, growing about the river of Amazons, and ailed by the Carribbees, kariarou, which yields a pulp as red as vermilion, (" une fascule aussi rouge que le vermilion d'Espagne,") and which the savages and Portugueze employ to dye their cotton hammocs. He calls it " convolvulus tinctorius folio vitigineo ;" I endeavoured, when in Guiana, to procure some of this colouring matter, but without success. The Danais of Commerson, is a creeping shrub, appertaining to the mibiacece of Jussieu, which, as we are informed by M. du Petit Thouars, the people of Madagascar employ as a red dye for the cloth which they weave from the thread of the tafia palm j but it has never been in my power to make any experiment with it. 31 a PHILOSOPHY OF CHAP. V. Of BrasH, and other Woods, affording red eolow ing Matters. Peragitur progressie colons rubci a Brasilio ligno, quod et Vcrzi Burn dicitur, ntruuque enira ipsius ligni nomtm like that of indigo, but probably not by a simi- lar change. I mean an absorption of oxygene, because, as Chevreul also observes, the colour is restored by adding potash, without any admission of oxygene, and because I did not find that a decoction of Brasil wood lost its colour by being mixed, and secluded several weeks in a close vessel, (completely filled} with sugar, and an oxide of tin, which was but little oxygenated, and, therefore, would have been capable of rendering indigo colourless. With solutions of alumine and of tin, em- ployed as mordants, this wood communicates a very lively and beautiful red to wool, silks, linen, and cotton; but unfortunately, its deficient per-| manency, especially on the latter, renders the PERMANENT COLOURS. 325 use of this wood much more limited than it would otherwise be. With solutions of iron the colour of Brasil wood may be darkened to as to produce violet and black colours, of greater permanency than the red, but less durable than similar colours, which are given by cheaper means. Alum, if put into a decoction ofBrasil wood, even after it has been made yellow by an acid, will re- store its red colour, precipitating a part of it, at the same time, and the remainder will nearly all subside, if the acid be saturated by the addition of an alkali. It is in this way that an inferior sort of carmine has long been produced,* for painting in water colours, and improving female complex- ions. The oxide also produces a fine rose-co- loured precipitate from a decoction of Brasil wood, even when it has previously been made yellow by an acid. I have found, by repeated experiments, that galls when employed with Brasil wood for dyeing upon the aluminous basis, have rendered the colour more lasting upon linen or cotton, and this fact seems to have been long known, for in the old book, mentioned at p. 248 of my first volume, it was directed that linen, intended * Caneparius says, p. 215, " Confident laccam ex Brasilio, Verzinove dicto ;" and tliat they made red Ink ' ' ex ligno Brasi- lio, sive Verzino." 326 PHILOSOPHY OF to be dyed with Brasil wood, should be prepared with galls and alum. Arsenic employed with alum, has likewise appeared to me, to render the red colour of this wood more lasting ; but I do not recommend this addition, because the use of it is liable to dangerous accidents. Having boiled broadcloth with sulphate of lime and a decoction of Brasil wood, for the space of one hour, I found it thoroughly dyed of a full crimson, which did not suffer greatly by a month's exposure to the sun, air, &c. To dye wool or woollen cloth with Brasil wood, upon the aluminous basis, the former is commonly prepared, as directed at pp. 384 and 385 of my first volume ; taking care, however, that the proportion of tartar be, to that of alum, only as one to five or six. But as that part of the colouring matter, which attaches and fixes itself most readily to wool or woollen cloth, does not produce the brighest colour, it is the common practice, first to dye some coarser cloth or stuff in the Brasil wood liquor, in order to deprive it of this least estimable part, before the finer cloth undergoes this operation. The liquor so im- proved, will also give a lively crimson to silk, which has imbibed the aluminous basis by the usual treatment. Calico, which had been printed with the acetate of alumine, and afterwards cleansed with a mixture of cow-dung in water, as is usual for calico printing, being dyed in a de- PERMANENT COLOURS. 327 coction of Brasil wood, obtained a fine crimson co- lour on the parts which had imbibed the alumi- nous basis, and a pale reddish discolouration on that which was baseless. Wishing to ascertain whether either the fat or the drying oils would afford any protection to the crimson colour so produced, I applied fine olive oil to some of the spots or figures which had received this colour, and linseed oil to others, and exposed the calico so dyed to the sun and air during ten summer days ; at the end of which, I found that the colour which had been covered by linseed oil, was greatly faded, and that which had been covered by olive oil, considerably more injured than the crimson in other parts, to which nothing had been em- ployed ; so that both kinds of oil, instead of re- tarding, had promoted, the decay of this colour. Broadcloth prepared in a bath of alum and tartar, with about half as much of the murio- sulphate of tin as would be required for a cochi- neal scarlet, and dyed with Brasil wood, acquired a very lively and beautiful colour of a passable durability. The nitro-muriate of tin, employed in the same way, produces nearly similar effects ; but, by employing a portion of galls with the Bra- sil wood and the nitro-muriate of tin, a durable orange colour was produced upon woollen cloth. M. Dambourncy asserts, (see Recueil de pro- cedes, &c. sur les Teintures, p. 172) that he had found, by his experiments, the bark of the white 32S PHILOSOPHY OF birch (betula alba) to produce very beneficial effects, in fixing the colour of Brasii wood, con- jointly with a solution of tin, made by equal parts of nitric and muriatic acids. But for this purpose he employed sixteen pounds of the birch bark to one pound of Brasii wood, which, he says, dyed four "pounds of wool, of the colour which formerly was called Venetian scarlet (ecar- late de Venise.) He seems to think this bark equally efficacious in fixing the colours of log- wood. I have reason, however, to doubt whether its effects are so considc able as he imagines, and the very great quantity, which he states to be ne- cessary for producing these effects, will probably discourage its use. As the oxide of tin has so little affinity for linen and cotton, it will hardly be supposed likely to give any considerable stability to the Brasii wood colour on these substances. It is, however, sometimes employed for this purpose, assisted by a large proportion of galls, or of su- mach, which last tends less to degrade the co- lour than galls, and with it, the Brasii wood gives to cotton yarn a sort of scarlet, which, not- withstanding its fugacity, is found to answer for some uses. A nitro-muriate of bismuth appeared, by my experiments, to be more efficacious than that of tin, for giving stability to the Brasii wood colour, both on wool and cotton, but it made the colour PERMANENT COLOURS. 329 incline more to a dirk crimson or purplish lint, than it does with the tin basis. The oxides of antimony and of zinc, applied to wool, gave dark brownish reds with this wood, but they were fugitive and of little value, and of stiil less on cotton. The nitrate of lead, employed as a mordant with Brasil wood, produced a good bright red upon wool ; but it d : d not prove sufficiently last- ing ; solutions of copper employed in the same way, produced dark but fugitive browns. Wool, prepared with a nitrate of lime, and dyed with Brasil wood, obtained a deep orange colour of passable durability ; and a lighter orange of less brightness was produced upon wool, by the sulphate of lime ; but on silk, the latter produced only a cinnamon colour, though the nitrate of lime produced a deep orange upon this substance. Cotton received no colour from Brasil wood with either of these mordants. ART. II. Sappan, or Sampfan, Wood. This is obtained from the caesalpinia sappan of Lin. a middle-sized tree, more prickly than the former, with leafits oblong-oval, unequal at ih« sides, obtuse and glabrous j calyx glabrous ; *J30 PHILOSOPHY OF stamina longer than the corols, and upper petal less. — See Roxburgh's Plants of Coromandel, vol. i. t. 1 6. It is indigenous to Siam, Pegu, the coast of Coromandel, and many parts of the East indies, and was described by Rumphius, (Am- boyna, iv. p, 56.) under the name of lignum sappan, and by Rheede (Hort. Malabar, vi. p. 3.) under that of isiapangam t Linscoten had pre- viously called it sapon. In some parts of Europe the name of sapon, or sappan, has been corruptly changed to that of japan. This wood seems to have been very generally employed for dyeing in the greater part of Asia, during many centuries, and to have found its way to Europe some time before the discovery of America ; though very little of it has been lately imported, except by the Dutch. The colouring matter of this species of csesal- pinia, differs but little from that of Brasil wood in its properties and effects, or in regard to the mordants required to produce these effects ; but there is a considerable difference in regard to the relative quantities of colouring matter which these woods afford ; that of the best sappan amounting, by my experiments, to little more than half as much as may be obtained from an equal weight of the Brasil, and the colour not being quite so bright. I am informed that some of the trees, affording the true sappan wood, are now growing at the PERMANENT COLOURS. 331 Isle de France, having been transplanted thither from Siam. As the bases,or mordants, proper for the sappan wood, and also the ways of using it, very nearly resemble those which are found to be most bene- ficial with the Brasil wood, they need not be par- ticularly described. More than twenty years ago, the late Mr. Nathaniel Smith, then Chairman of the Court of Directors of the East India Company, put into my hands parcels of a species of red wood, which had been recently discovered at the Andeman islands ; and of another red wood from the coast of Coromandel, with a request, that I would ascertain their properties for dyeing, compared with those of the true sampfan, or sappan, wood, from Siam, of which he also gave me a small parcel. The results, however, of my experi- ments were not favourable to either of the two first of these woods, as their colouring matter was but partially soluble in water, and both, in quantity and quality, appeared to be greatly in- ferior to that of the wood from Siam. The red wood of the Andeman islands, however, being boiled in water, with a little soda to render its colour more soluble, appeared, in one respect at least, to resemble the lignum nephriticum, as its decoction, viewed by reflected light, exhibited a full bright blue colour, whilst, by transmitted light, it was red. 352 PHILOSOPHY OF ART. III. Nicaragua, or Peach Wood, called by the French Bois da Sainie Marihe. This seems to belong to the genus caesalpinia, though the species has not, as I believe, been suf- ficiently ascertained. Sir Hans Sloane, in his Natural History of Jamaica, has mentioned it as growing about Nicqja, on the coast of the South Sea, or Pacific Ocean, and being thence brought by the Lake of Nicaragua to the North Sea. It is almost as red and heavy as the true Brasil, but does not commonly afford more than a third part in quantity, of the colour of the latter ; and even this is rather less durable and less beauti- ful than the true Brasil wood colour, though dyed with the samemordants. Itseemstobethecuraqua, seu Brasilium Hispanorum, of Hernandez, (p. 121,) and is called, (though I know not why) stock-vish-hout, or stock-fish wood, by the Dutch. The woods sold under the name of Nicaragua, or peach wood, differ greatly in their quality as well as price ; one sort being so deficient in colouring matter, that six pounds of it will only dye as much wool or cloth as one pound of Bra- sil wood, whilst another variety of it, growing principally about the Rio de la Hacha, eastward of Santa Martha, will produce nearly half the effect of an equal quantity of Brasil wood, and sell proportionably dear j and it is this sort which PERMANENT COLOURS. 335 they distinguish by the name of stock-fish wood. Dampier mentions another variety, called blood wood, growing about the gulph of Nicaragua, and similar, as he thinks, to camwood. The way of employing the Nicaragua wood, and the mordants used with it, differ so little from those which are thought most suitable for Brasil wood, that any particular explanations on this subject would be superfluous. ART. IV. - Ccesalpinia Brasiliensis, or smooth-leaved BrasU letto. This is the pseudo santalum croceum of Sir Hans Sloane, (Jam. ii. p. 1 84,) and the first cse- salpinia of Brown, commonly called, Jamaica brasiletto, or Jamaica red wood. It is one of the cheapest and least esteemed of the red dying woods. ART. V. CjfesALPiNiA crista ; the Bahama, or broad-leaved prickly brasiletto, of which Catesby has given a description and figure (Carolina, vol. ii. 51.) He adds, " the inhabitants of the Bahama islands for- SS4 PHILOSOPHY OF merly got a great part of their subsistence by cutting this wood, but it is now much exhausted." I have mentioned the wood of this and the pre- ceding article as belonging to different species of caesalpinia, on what is deemed the best autho- rity, but their distinctions do not seem to have been well ascertained, and I think it very proba- ble, that they are but varieties of one species. Both are commonly employed for dyeing inferior and fugitive red colours, upon the aluminous basis. ART. VI. Camwood, This was first brought to Europe from Africa by the Portuguese, who called it pao-gaban, or gaban wood, having found it near the river of that name. Finch afterwards mentioned it as growing near Sierra Leone, and being there called kambe ; whence, by abreviation, the name of cam, or kam, has been formed. It appears to be the heart of a tree, which bears legumes, and is nearly related to the genus caesalpinia, and which professor Afzelius has lately made the foundation of a nexv genus, with the name of tespesia. This wood affords a red colouring matter, dif- fering but little from that of the ordinary Nica- ragua wood, either in quality or quantity ; and it may be employed with similar mordants. PERMANENT COLOURS. 335 ART. VII. Barwood. This is another African production, imported subsequently to the former, and principally from Angola. It does not appear to contain any tan- nin. Upon the aluminous basis, it gives yellow- ish brown reds to wool and cotton, of considera- ble durability on the former, though rather fugi- tive on cotton. This colour may be saddened and varied, by employing solutions of iron or copper with it, either alone or conjointly with alum. The dark red, which is commonly seen upon the British imitations of Bandasna, or East India silk handkerchiefs, is commonly produced by the colouring matter of barwood, saddened by sulphate of iron t and being so saddened, it is now very much employed to give dark grounds for deep blue colours, dyed with indigo, and there- by produce a saving of the latter. It commonly bears about half the price of camwood. I have not been able to obtain any accurate information concerning the tree which affords this wood. An inferior sort of it is imported from Old Cala- bar. Mr. Clarkson has stated, that an African wood vessel, brought home accidentally among her bar- wood, a small billet of a superior colour to the rest ; that one half pf it was cut away for expe- S36 PHILOSOPHY OF riments, by which " it was found to produce ja colour that emulated the carmine, and was deem- ed so valuable in the dyeing trade, that an offer was immediately made of sixty guineas per ton, for any quantity that could be procured.'* He has added, that the other half of this billet was " sent back to the coast, as a guide to collect more of the same sort •" but with what success, I know not. ART. VIII. lied Saunders, The wood brought from Coromandel, under this name, (pterocarpus santalinus) is employ- ed to dye lasting reddish brown colours upon wool, though but a small portion of its colouring matter is soluble by water alone; and even when assisted by potash, or soda, the solution is incomplete ; this difficulty may, how- ever, be in some degree overcome by employing the rasped wood with sumach, galls, or the rinds of walnuts. Broadcloth, prepared (as usual) with alum and tartar, being boiled in water with equal portions of ground sumach and rasped saunders, was dyed of a very bright and lasting reddish orange. In several experiments, I found a diluted sulphuric acid to act very efficaciously in extract- ing the colour of this wood. PERMANENT COLOURS. 357 Voglcr gave, as he asserts, a colour to wool almost equal to scarlet, from this wood, after extracting the colouring matter by spirit of wine ; but this menstruum would prove too costly in Great Britain for this use. vet. 11. ■ 338 PHILOSOPHY OF CHAP. VI. Of Logwood. Or, " what Campcachy's disputable shore Copious affords to tinge the thirsty web." Dyer's Fleece. The tree producing this wood, is the liccmatoxy- lo?i* Campechianum (Lin.), with crooked spinous branches, leaves abruptly pinnate, leafets inversely heart-shaped, and flowers racemed ; the latter are succeeded by small flat lanceolate capsules, about two inches long, and containing each five or six small flat seeds. Like the genus coesalpinia, it belongs to the natural order of lomentaceac, and the leguminosae of Jussieu.f * The name of hoemaioxyioii is formed of two Greek words, signifying Hood wood. t Both Sloane and Catesby have described and figured this tree, which grows so rapidly, that in four years after the seed has been planted, the stem often acquires its greatest circum- ference, which is about two feet. Dampier says, " when the old tree is cut, the sap is white, and the heart red ; the last being only used for dyeing, they chip off all the white sap before they carry it on board." It commonly grows, and is supposed to thrive best, in a wet soil, with a large proportion PERMANENT COLOURS. 339 This tree has been transplanted from Cam- peachy and Honduras, to most of the West India islands. Sir Hans Sloane mentions Mr. Barham as having brought the seeds from the former of these places, in 1715, to Jamaica, where it now occupies many large tracts of ground, particu- larly in the neighbourhood of Savanna-la-Mar. The Spaniards first became acquainted with this wood, and gave it the name of palo Campechio, whence it was called campeche wood, by some of the first English writers, by whom it was men- tioned, particularly Chilton, Parker, and Middle- ton (in the collections of Hackluit and Purchas.) But in the voyage of the Earl of Cumberland, it of clay. The bark of the branches, and of the very young trees, is light-coloured and smooth \ but that on the stems of the old trees, is rough and dark coloured. Hitherto the bark has been all thrown away, though, from some few experiments which I have made with it, I am convinced it might be usefully and profitably employed in dyeing, though its colouring matter differs greatly from that of the wood. The younger trees are most thorny. Dr. Robertson (Hist, of America, vol. iii. p, 235, 8vo.)S;iy§, "the logwood produced on the West Coast of Yeucatan, near the town of St. Francis, where the soil- is drier, is in qua- lity far superior to that which grows on the marshy grounds, where the English are settled." Dr. Robertson has here adopted an opinion, which the Spaniards have endeavoured to propagate, in order that the logwood which, since the peace of 1783, they have allowed to be imported, free of duty, from Campea- chy, might obtain a preference in the market, over that of Honduras, cut by the English } but I do not find it to be well founded. z 2 340 PHILOSOPHY OF was soon after mentioned under the name of logwood, which name seems to have prevailed in this country over the former, as that of bois d'Inde* has among the French, over the appella- tion of bois de Campeche, which they also first gave it s Logwood seems to have been first brought to England, soon after the accession of Queen Eli- zabeth, but the various and beautiful colours dyed from it, proved to be so fugacious, that a general outcry against its use was soon raised, and an act of parliament was passed in the 23d year of her reign, which prohibited the use of it as a dye, under severe penalties ; and not only autho- rized, but directed the burning of it, in whatever hands it might be found within the realm ; and though this wood was afterwards sometimes clan- destinely used, (under the feigned name of black- wood,) it continued subject to this prohibition for nearly one hundred years, or until the passing of the act of the 13th and 14th of Charles the Second j the preamble of which declares, that * This name of bois d'Inde, seems to have misled Berthollet to suppose, (torn. ii. p. 243) that the Jamaica pepper, pimento, or allspice, (obtained from the myrtus pimenta), and the logwood, were produced by the same tree; Dutertre, Rochefort, and others, having early distinguished that species of myrtle, or, perhaps, more strictly, the myrtus acris, by the nam* of bois d'Inde, which it still bears at Martinico, and other Frencb West India islands. PERMANENT COLOURS. S41 ;t the ingenious industry of modern times, hath taught the dyers of England the art of fixing the colours made of logwood, alias blackwood, so as that, by experience, they are found as lasting as the colours made with any other sort of dyeing wood whatsoever ;" and on this ground it repeals so much of the statute of Elizabeth as related to logwood, and gives permission to import and use it for dyeing. Probably, the solicitude of the dyers to obtain this permission, induced them to pretend that their industry had done much more than it really had, in fixing the colours of log- wood ; most of which, even at this time, are notoriously deficient in regard to their durabi- lity. Six quarts of distilled boiling water, may be made to extract nearly all the colouring mat- ter of ome pound of logwood properly chipped, and when so extracted, the decoction will be yellow, with a sweetish taste, and will contain, in addition to the colouring matter, a volatile oil, with small portions of lime and potash, in union with acetic acid, besides some other matters of no importance, in regard to its effects in dyeing. Tannin has been generally considered as one of the constituents of an aqueous extract of log- wood, but without reason, as the infusion or decoction when recently made, does not coagulate or precipitate a solution either of glue or of isin- 312 PHILOSOPHY OF glass ; and the appearance of such precipitation, which is sometimes produced, results from a sub- sequent absorption of oxygene, for which the colouring matter of logwood has, whilst moist, a strong attraction. If the decoction be made with common, instead of distilled water, it will exhibit not a yellow, or an orange, but a full red or dark blood colour, by reason of either the selenite, or the calcareous earth which such water generally contains ; but by adding to it sulphuric, nitric, or muriatic acid, the,, yellow will be restored, and a subsequent addition of any of the alkalies, in a proportion sufficient to supersaturate the acid, will re-produce the purple colour. When logwood is of good quality, it will yield from one fifteenth to one twentieth of its weight of pure colouring matter, which will be soluble in alcohol and in water, if the decoction, after being made, has been speedily evaporated to a dry state by fire ; but if an interval of several weeks is allowed previously to intervene, or if the evapo- ration be slowly performed, by exposing the decoc- tion to the sun and air, even in summer, or in a hot climate, the colouring matter will absorb and combine with a large proportion of oxygene, and become, in a great degree, insoluble by water, and the colours dyed from it will prove much more fugitive than those produced by the decoc- PERMANENT COLOURS. 343 tion when recently made.* A circumstance in which it differs greatly from the colouring mat- ter of Brasil wood ; which last, probably might, with greater advantage than almost any other, be brought into the form of an extract, (for the use of dyers) at the place of its growth, to diminish or obviate the expence of transporting the wood to a sea port, and its subsequent freight to Europe. This strong attraction of the colouring matter of logwood for oxygene, may, perhaps, be a cause of the want of permanency in the colours dyed with it, though we find an equal want of per- manency in those obtained from the Brasil wood, whose colouring matter combines but slowly with oxygene, and is benefited rather than injured by * I found this to be the case of a large parcel of an extract of logwood, which had been prepared in the West Indies, merely by exposing an infusion or decoction of the wood to the sun's rays ; it had a fine bright glossy aspect, produced by very small crystals ; but a large proportion of it was nearly insoluble by water, and the colours dyed with it were uncom- monly fugacious. Having formerly attempted to substitute the dry extracts of various dyeing drugs, for the drugs in their natural state, in order to diminish the expence of freight, &c. and such attempts having, in almost every instance, been attended with disappoint- ment and loss, by reason of the changes to which colouring- matters are liable, by the operations necessary for their extrac- tion and evaporation, it becomes me to recommend caution to those who may be disposed to engage in similar undertakings. 544 PHILOSOPHY OF such combination, as is indeed the case of many other colouring matters.* By adding a sufficient portion of alum to a decoction of logwood, the colouring matter may be all made to unite with the alumine, and form a purple or reddish violet compound, separable by the filter so completely, that the water will * M. Chevreul supposes, that the extract of logwood con- tains two sorts of colouring matter, one, which he calls hae- matine, which is susceptible of crystallization, and soluble both by water and by alcohol, giving them a reddish orange colour, and the other denominated by him, " matiere d'un rouge maron," which is not soluble by water. This last he considers as possessing most of the properties of those vege- tables which are called astringent, and especially that of causing a precipitation of gelatine. I am persuaded, however, that this insoluble matter, which occurs only after the colouring matter has been evaporated to dryness, is merely the product of a com- bination of oxygene, with a portion of that which he calls haematine. I have found repeatedly that a decoction of log- wood, after being kept five or six weeks in hot weather, lost the sweetness, and acquired the very properties which he ascribes to his " matiere d'un rouge maron," including that of pre- cipitating a solution of isinglass. But this precipitate differs from that produced by the tanning principle, because it is soluble in boiling water, which that of tannin is not, and this single fact proves, that the precipitation which does not take place with a recent dicnction of logwood, results from a subsequent change, •and a newly-acquired property, differing essentially from that of the tanning principle. For the rest, M. Chevreul admits, that the supposed two sorts of colouring matter are both attracted by the same bases, and applicable in dyeing with the same mordants. See Ann. de Chimie. torn. 81 and 82. PERMANENT COLOURS. 345 run from it colourless. When not filtered, a great part of the compound will subside, but not the whole*, unless an alkali be added. By employing a sulphate of iron instead of alum, a similar com- bination will take place, and a blueish black colour will be thereby produced. All the solu- tions of tin produce purple or violet colours with the decoction of logwood, and a complete precipi- tation of the colouring matter. Solutions of the other metals and earthy bases will also combine with the colouring matter of logwood in dif- ferent proportions, and with different degrees of affinity, producing various colours and preci- pitates, to be noticed hereafter. Sulphate of copper added to the decoction of logwood, gives it a purplish blue colour ; sulphate of pure zinc added to a similar decoction, produces a dark purple ; nitro-muriate of gold, an orange ; muriate of quicksilver, an orange red ; muriate of antimony, a beautiful crimson ; acetate of lead, a garter blue ; arseniate of potash, a deep yellow ; muriate of barytes, a reddish purple ; nitrate of barytes, a brownish purple ; strontia earth, a violet ; sulphate of magnesia, a purple ; muriate of magnesia, a yellow ; sulphate of lime, a purple ; and muriate of lime, a violet purple. These effects show that the tingent matter of logwood, is capable of producing, with different mordants or bases, almost all the possible varieties of colour. Sulphuretted hydrogene gas, produces a disap- MS PHILOSOPHY OF pearance of the logwood colour, like that which it occasions to the colour of Brasil wood, and, undoubtedly, in the same way, i. e. merely by combining with it, and not by any deoxygenating effect. Wool dyed with a decoction of logwood in hard water, obtained a purple colour, which, by exposure to the sun and air, speedily changed to a drab colour ; and this last afterwards manifested considerable stability. Chips of logwood being put into water, acidu- lated by sulphuric acid, and boiled therein, pro- duced a brownish yellow decoction j and wool dyed therewith obtained a strong yellowish bright snuff colour, which, being exposed to sun and air during five weeks, manifested considerable stabi- lity. Nitric acid being mixed with a decoction of logwood, produced a fine bright yellow. But this, by boiling, gradually became a yellowish brown, and communicated that colour to wool dyed therein ; which being sufficiently exposed in the open air, proved to be a lasting colour. Woollen cloth being boiled during one hour in water, with a suitable portion of sulphate of Erne, and afterwards dyed with logwood, ac- quired a full and bright, though brownish, orange, which proved lasting. Cloth boiled with a decoction of logwood in PERMANENT COLOURS. 347 water, slightly acidulated by muriatic acid, took a brownish yellow colour. Cloth boiled with muriate of lime, and dyed with logwood, took a brownish orange colour, which; however, did not prove sufficiently du- rable. Wool dyed with logwood and sulphate of magnesia, received a yellow colour, but it proved very fugitive. Woollen cloth prepared with alum and tartar, as usual, being dyed with logwood, obtained a bright violet colour, which, by adding a little muriatic acid to the dyeing liquor, may, as I have found, be made to incline more to the red or purple, but neither of these colours have the de- sired stability ; though the former is not unfre- quently employed. The best and least fugitive of the purple or violet colours obtained from logwood, are pro- duced by mordants principally composed of solu- tions of tin : one of these became very fashion- able in France, about thirty years ago, under the name of prune de Monsieur ; and being then resident at Paris, I wore a coat of this colour, without having had any reason to complain of it as being fugitive. Of the invention ?.nd compo- sition of this colour, an account given by M. Descroizilles, (a chemist at Rouen,) to M. Ber- thollet, was published by the latter, in the first edition of his Elements, he. from which it ap- ses Laines, &c. — Preface. ART. I. Of the Bark of the Rhizophora Mangle, or Man- grove Tree. This is one of three vegetable colouring matters, of which, in consequence of my discovery of their properties, the use was exclusively vested in me for a term of years, by an act of parliament, as lately mentioned ; and the tree producing it grows abundantly on nearly all the sea-coasts between the tropics, round the globe, and is emi- nently remarkable for the singularity of its pro- pagation, not only by seeds, which germinate downward several inches, while actually adhering to the branches of the tree,* but also by a great • * Whence its generic name of rhizophora, from two Greek words, which signify root bearing. PERMANENT COLOURS, number of long round appendices, which, like ropes of different lengths, constantly shoot down from the under sides of most of the branches to the earth, and taking root in the mud, each be- comes at first a fulcrum or prop, to support the parent tree against the impetus of the tides and waves of the ocean, and afterwards forms the stem of another tree, which propagates itself in like manner ; so that impassable forests are formed, extending many leagues, and nearly all the trees composing it are connected with each other, either by their branches or their roots, of which many, by extending horizontally upon the surface of the earth, arrest and accumulate great masses of earthy and vegetable matters, and thus enable the land constantly to encroach upon the sea, and produce that vast extent of alluvial grounds which has been formed within the tropics. Oviedo, Clusius, De Laet, and other early writers, have mentioned this tree by the name of mangle, which it bore among the natives of Hispaniola ; Linschoten gave it the name of arbor de raiz ; and Rochefort, that of paretu- vier, or paletuvier, which it retains among the French ; whilst the Dutch call it, duizen-beenen, or thousand legs, from its numerous props or supporters. Tfcere are two varieties of this species of rhizo- phoia, one of which is called the red, and the other the imrple or violet mangrove ; and the 3 GO PHILOSOPHY GF barks of both are nearly half an inch thick, of a reddish brown colour, and replete with colouring matter and tannin ; both of which may be nearly all extracted by water employed in a sufficient quantity. Wool, or woollen cloth, prepared as usual with alum and tartar, and dyed with only one-twen- tieth of its weight of powdered mangrove bark, ac- qu re sa bright, full, and lasting annotta,or reddish, though somewhat brown orange colour. The solu- tions of tin, employed as mordants, do not con- siderably raise or improve the colour of this bark upon wool ; though they produce what Darnbour- ney calls, " unmordore solide." By substituting the sulphate of iron for alum, wool or cloth'tftll obtain from the mangrove bark, a Listing chocolate brown colour, much darker than the same means will produce upon linen or cotton ; and by employing with the sul- phate of iron, one-sixth of its weight of carbo- nate of lime, a very dark and durable drab, or slate, colour will be produced. Sulphate of cop- per, instead of sulphate of iron, produces, with the same means, a permanent cinnamon brown. The natural colour of the mangrove bark, or that which it communicates to linen and cotton upon the aluminous basis, is a kind of salmon, or reddish nankin colour, for which it has hitherto been chiefly employed in this country, particularly at Manchester. Probably the cheapest and best mordant for this colour is made by dissolving PERMANENT COLOURS. 3 b' I eight pounds of alum with one pound of clean chalk or whiting, in six gallons of water; in which, after the solution is effected, the cotton may be soaked twelve hours, then dried, and after- wards dipped into lime water ; drying it again, and then soaking it a second time, for about five minutes, in the solution of alum ; after which, being well dried and moderately rinced, it may be dyed with about one-twentieth of its weight of the mangrove bark in powder, adding a little when the colour is sufficiently raised. B\ substituting the sulphates of ircn and cop- per, as mordants, as well as by mixing then .h alum, a great variety of brown, olrve, and diab colours may be cheaply dyed from the mangrove bark, upon fustians, cotton, velvets, &c. which will prove it ore lasting, and much less susceptible of accidental spots and discolourations than simi- lar colours, commonly dyed from the morus tinc- toria,&c. The mangrove bark may be employed by the calico printeFs for dyeing pieces printed with the acetates of alummeand ofiron> upon which it will produce reddish orange and slate colours, with- out considerably staining the white grounds. This bark will also afford several prosubstantive co- lours, applicable by the pencil, and of considera- ble durability. One of these, a salmon or reddish cinnamon colour, may be made by mixing a very strong decoction of the mangrove bark, with the acetate 36'i PHILOSOPHY OF of alum in c, and afterwards thickening the mix- ture as usual ; and this may be improved by add- ing to it a little nitro-muriate of tin ; or which is better, a murio-tartrite of that metal. A similar decoction of this bark, mixed with the acetate of iron, will produce a lasting prosub- stantive dark drab, or slate, colour. ART. II. The Rhizophora Gymnorhiza, Is another species of this genus, producing very large trees, which cover an immense tract of sea-coast along the southern shores of Cochin-china and Cam- bodia, as well as in the Straits of Malacca ; and is supported by numerous and widely-spreading arcu- ated roots, which are generally overflowed by the tide at high water. Lourciro says, the thick red- dish brown bark of this tree is highly useful in dye- ingrufous,or chesnut colours, which are easily con- verted to black,by alternately dipping the cloth (pro- bably cotton) into a decoction of the bark, and then into a mixture of dark brown mud and water, then drying and repeating the dippings, until the desired colour is obtained ;* and this black he re- * " Utilissimus est ad tingendos telas colore rufo vel casta- neo j qui facile in nigrum mutator, si alternis vicious imrner- gantur telae cceno fusco aqua diluto/' &c. — Cochin-china, torn. i. p. 297. PERMANENT COLOURS. <*63 presents as permanent. The mud employed for this purpose, doubtless, contains an oxide of iron ; but if this will render the colour black, there must, in that respect, be a considerable difference between the colouring matters of this, and the former species. ART. III. The Baric qf the Mahogany Tree, (Siveitenia Makogani,) Possesses colouring matter, so nearly similar to that of the mangrove, that no additional ex- planation can be wanted respecting the effects which it produces with different mordants, or the . methods of applying it for dyeing, except- ing only the circumstance of its affording about one-third less of colouring matter, than an equal weight of mangrove bark. ART. IV. The Bark of the Acer Rubrwn, or Scarlet Flow- ering Maple of North America, (described and figured by Catesby, torn. i. p. 62. J Produces a very lasting cinnamon colour with the aluminous basis, not only on wool but on cotton j and with the sulphate, or the acetate of §■■■ 364 PHILOSOPHY OF iron, it communicates to both, a more intense , pure, and perfect black, than even galls, or any other vege- table matter within my knowledge, and it has the advantage, in calico printing, of not only not s:ain- ing the white grounds, but of obviating (like the d'howah, lately mentioned) the stains which some other colouring matters would produce withoutit. The leaves of this species of maple produce ef- fects nearly similar to the bark. ART. V. American Oaks. I have made experiments with nearly all the twenty species of American oaks, described and figured by the elder Michaux, and they have all, excepting the quercitron oak, and some few va- rieties possessing similar properties, appeared to contain large proportions of a colouring matter which, with the aluminous basis, produces cinna- mon browns, and with that of iron, blacks, more or less perfect. ART. VI. Pinus Abies Americana, or Hemlock Spruce. The bark of this tree, which is employed in Nova Scotia to tan leather, affords a colouring matter PERMANENT COLOURS. 365 which, with an aluminous basis, produces a lasting bright reddish , brown colour upon wool, and a nankin colour on cotton, which, however, on the latter, is a little deficient in durability. "With either sulphate, or acetate of iron, this bark produces dark drab and slate colours ; but not a biack. ART. VII. Juglans oblonga Alba, or North American Wliite Walnut, commonly Butternut. In Dr. Birch's History of the Royal Society, it is stated that this learned body received, on the 10th of February, 1669-70, from Mr. Win- throp, one of the Fellows, some stuff, manufactured in New England from a mixture of cotton and wool and sent by him " to shew the colour, which was only dyed with the bark of a kind of wall- nut tree, called by the planters butternut tree, the kernel of that sort of walnut being very oily, whence they are called butternuts. They dyed it only with a decoction of that bark, without alum or copperas." I have been, from a very early part of my life, acquainted with this tree, and have made nume- rous experiments with its bark, the colouring matter of which, has, indeed, so much affinity with wool, that, without any mordant or basis, a decoction of it will dye woollen stuffs of a du- IWT TMTiWnTTTl sec PHILOSOPHY OF rable tobacco brown, which may, however, be improved, both in brightness and permanency, by an aluminous basis ; and this last is necessary to fix this colour upon linen or cotton. With either the sulphate or acetate of iron, this bark com- municates to wool, linen, and cotton, a strong and lasting black colour, and calicoes printed with the acetates of alumine and of iron, separately, and also mixed, being dyed with this bark, will re- ceive various shades of brown, drab, and black colours, sufficiently permanent, and without any stain or discolouration of the white grounds ; a decoction of this bark, in which a little gum ara- bic had been dissolved, having, in the course of my experiments, been mixed with a solution of iron by nitric acid, the whole was instantaneously converted into a solid blackish mass, which re- quired considerable trituration in a glass mortar, with hot water to divide and render it soluble again. I repeated the experiment afterwards, with a similar effect ; though nothing like it was produced bv anv other metallic nitratp, of which I mixed several with a similar decoction of this bark. The rinds of the nuts of this tree possess the same colouring matter as the bark ; and both afford an extract, which is much es- teemed in the United States of America as a mild cathartic. PERMANENT COLOURS. ARTICLE. VIII. 3(7 The Juglans Nigra Oblonga, or Oblong-fruited Black Walnut of North America, Affords, by its bark, and the rinds of its nuts, a dark brown colouring matter, which, on the alumi- nous basis, communicates to wool and cotton a sort of durable tobacco, or chesnut brown ; and with. solutions of iron, a brown considerably darker ; my experiments, however, with this vegetable, have been but few. Dambourney says, that with a nitro-muriate of bismuth it gave to wool a very lasting puce, or flea colour. ART. IX. The Juglans Regia, or Common Walnut, Affords in the rinds of its nuts a colouring matter, which, though naturally almost limpid, changes to a dark brown by exposure to atmospheric air, whence it probably absorbs oxygene ; of this change proofs are in the autumn frequently seen, upon the hands of those who employ themselves in separating these rinds from the nuts. Bracon- not, from a series of experiments upon these rinds, infers, that they contain starch, and an acrid bitter substance, which, by combining with oxy- gene, becomes carbonaceous ; also malic acid, citric 90S PHILOSOPHY OF acid, tannin, phosphate of lime, oxalateof lime, and potash. He says, the recent juice being filtered, exhibits an ambour colour, but with sulphate of iron changes to a dark, or blackish green. The colouring matter of walnut-rinds has a decided affinity with wool, and being applied to the latter by dyeing, without any mordant, gives it a brownish cinnamon colour, of considerable durability, though it may be rendered brighter and more lasting by an aluminous basis ; but on cotton I have not found it produce very lasting colours, even with that or any other basis. These rinds are most frequently employed to produce, without any basis, particular shades of brown or dark colours, upon wool or woollen stuffs, after having been left to macerate in water, and undergo a sort of putrid fermentation during several months. The unfermented rinds, how- ever, with solutions of copper, iron, bismuth, &c. may be made to communicate very lasting ches- nut drab, slate, and other dark colours, to wool or cloth. ART. X. The Baric of Alder, Be tula Alnus, Possesses a colouring matter which, with the aluminous basis, dyes a permanent and very full, though brownish yellow, or orange,upon wool, cot, PERMANENT COLOURS. 369 ton, &c. and one which is brighter with the solu- tions of tin. With the sulphate, or acetate, of iron, it forms a black, and has long been benef.ciaily employed with galls, &c. in forming the black vat for dyeing that colour upon thread and cotton yarn. ART. XL Areca Nuts. It having been reported that the areca, or Pynang nuts, produced by the areca palm, were employed by the people of Malabar to dye a red colour, I procured and made trial of a parcel of the n ; but without obtaining any effects which might not be as well procured from many other vegetables, and even from the alder bark, last mentioned. With alum these nuts produced a sort of reddish cinnamon colour, and with iron, a brownish purple black, both of which appeared to be lasting.* * Some time after my experiments with these nuts had been made, I found, by looking into Loureiro's Natural History of Cochin-china, (original LUbon edition, p. 507, & seq ) that I had mistaken their proper use. He mentions this species of palm as being extensively cultivated in that country, for the sake of the nuts, and that the fullers make a decoction from them, and apply it to cloths already dyed, to render their colours more bright and lasting. " Fullones telas quascunque imbutfre, ut colores diutius servent, et melius expriment^ He adds, that they produce this effect by an agglutinating, and not by an astringent, power, (" vi glutinante, non adstrin- gente,") and that for this use many cargoes were sent annually from Cochin-china to China. VOL. II. , Bb H^HB 370 PHILOSOPHY OF ART. XII. The Ripe Berriesof the Privet,(LigustrumVnlgare) Being employed as a dye, produced, with the aluminous basis, a light apple green, on wooi and cotton, and a bluish black colour upon wool. Canneparius mentions them, (p. 204) as having been anciently employed to make ink, and, in- deed, they seem to have been the berries to which Virgil, in one of his Eclogues, applied the name of vacciniumj* but Caneparius appears to have mistaken this shrub for that of the hinna, or law- sonia inermis, which Prosper Alpinus had sup- posed to be a species of ligustrum. ART. XIII. The Myrobalan. This name has been given in the East Indies to the drupaceous fruit, of two species of termi- nalia, (viz. Indica, and chebula) as well as to that of the phyllanthus emblica ; which last appears to be the myrobalanus of Bontius, and myrobalanus emblica of Lourciro, p. 553. I have already, at p. 3.51 of my first volume, noticed the termir.alia chebula, (which is the terminalia citrina * " O formose pner, nimiura ne crede colori • Alba ligustracadunt, vacciuia nigra leguntur. PERMANENT COLOURS. 371 of Roxburgh, or yellow myrobalan of the shops) and the galls produced on its leaves, as being employed in the East Indies to give a yellow co- lour on cotton ; but I did not include either of these among the adjective yellows of this third part of my work, because, though employed as such in that country, from a paucity of yellow dyes, the colour which they afford partakes so much of a brown tint, as to have but little more right to be deemed a yellow, than that of the alder bark. Their colouring matter is, however, capable of being rendered highly useful in giving a perma- nent black with an iron basis, especially upon cotton, as will be seen in the chapter allotted to that subject.* ART. XIV. Paraguatan Bark. The xxiii. vol. of the Annales de Chimie, contains the translation of a report given by Do- * A ship bound from Cayenne to France, was captured a few years since with a carious collection of the animal and vegetable productions of Guaina, including a dyeing wood, labelled " Bois d? Sassafras de Cayenne" which last, the agents for the captors sent to me. It was very heavy, close grained, and of a reddish cinnamon colour; and, consequently, unlike the laurus sassafras Upon the aluminous basis it dyed a very high orange colour, ( which, however, was not lasting upon cot- ton) and with iron it gave dark browns. Bb 2 3 72 PHILOSOPHY OF minique Garcia Fernadez, of some experiments which he had made, by order of the supreme council of commerce in Spain, with the bark of a tree growing in the Spanish part of Guiana, and there called paraguatan, or parugatan ; which bark he represented as affording a dye in some respects superior to those of madder and Brasil wood, and as being capable of giving to silk, duly prepared, the various shades of rose and red poppy colour, obtained from samower ; and though this gentleman's report did not manifest much know- ledge, either of the principles or practice of dye- ing in the reporter, I was induced, by the inter- vention of a friend, to procure some of this bark from Cadiz ; but, after several trials, I found myself unable to obtain from it any thing better than a pale salmon colour, too fugitive to be of any value ; I, therefore, notice it here, only that I may obviate disappointment, and, perhaps, loss to those who might confide in, and act upon this report. ART. XV. Galls. These are excrescences, produced upon several species of oak, by the cynips quercus, or gall fly, which, by its peculiar structure, is enabled and disposed to deposit its eggs in the young PERMANENT COLOURS. 373 branches, and other parts of the several species of oak, and thereby occasion a protuberance which increases, until the larva of the insect gnaws through its prison or nidus, and escapes, leaving a perforated cavity therein. The galls, so perforated, are commonly of a light colour, and called white galls. Those in which the larva dies, and which have, therefore, no perforation, are commonly called blue galls, being of a darker colour, and affording commonly about one-third more of co- louring matter, than an equal weight of the white galls. Until lately the best galls were brought from Smyrna, Aleppo, and Tripoli ; but, at present, a considerable part of those which were formerly exported from the two first of these ports, are car- ried by another direction from the places where they grow to the East Indies, and are thence shipped to this country. Pliny informs us, (lib. xvi. c. 7.) that the galls most esteemed in his time wore those of Comagena, and that the least esteemed were those commonly produced upon the quercus robur. By long boiling, nearly seven out of eight parts of a given quantity of powdered galls may be dis- solved in about ten times its weight in water ; after which, Newman found that alcohol would only ex- tract four grains from a residuum of two drachms. The solution, so performed by water, besides matters of less importance, contains colouring 374 PHILOSOPHY OF matter, tannin, and a particular acid, (to whica the name of gallic acid has been given) all inti- mately combined ; though the first, and most important of these matters, has hitherto been confounded with the others. This colouring mat- ter precipitates, as I believe, ail the metals from their solutions, and the several precipitates, as far as my notes extend, retain nearly the following colours: viz. that of platina, an olive green; that of gold, a greenish brown ; mercury, yellow ; lead, white or grey ; silver, brown -, copper, brownish yellow ; tin, greyish white ; cobalt, pale blue ; bismuth, greenish yellow ; antimony, bluish white ; zinc, a slight greenish brown ; nickle, white ; columbium, an orange, (according to Dr. Wollaston); osmium, a purple, which changes to a deep blue ; and finally, that of iron exhibits a black, which, being diluted, or thinly spread, inclines, more or less, to blue or purple, according to the degree of acidity in the solution whence the precipitation is effected. This last, is the most important and remarkable property of galls; and as many opinions, which to me-seem erroneous, have been inculcated respecting it. by the highest authorities, and generally adopted, I shall, in a succeeding chapter, endeavour to ascer- tain the truth in regard to this subject. Heie it only remains for me to notice the light cinnamon fawn, or fauve, colour, which galls (like many others of vegetables mentioned in this diaper) PERMANENT COLOURS. 37$ afford, particularly to cotton upon the aluminous basis ; and which enables them, as I have found by repeated experiments, to communicate by dyeing a durable nankin colour to calico or to cotton yarn, after the latter has been macerated in milk, then dried, and soaked in a saturated solu- tion of alum, with one-eighth of its weight of lime, afterwards rinced, and dryed, previously to its being dyed in a decoction of this vegetable. A diluted nitrate of lead employed instead of the solution of alum, produces a similar and equally durable colour. I will observe here, as I shall have no other op- portunity of doing it, that some few vegetables, particularly the Peruvian bark, that of the cherry tree, and that of the horse chesnut, (cesculus hip- pocastaneum) possess the property of producing a greenisih olive colour with sulphate of iron ; a property which M. Braconnot ascribes to a por- tion of phosphoric acid, which he found them to contain, conjointly with a yellow colouring matter. — See Ann. de Chimie, torn. 70, p. 290. Poerner asserts, that chamomile flowers, with sulphate of copper, will dye wool of a durable green colour, and that fenugree seeds will pro- duce a colour nearly similar, with the same basis. 376 PHILOSOPHY OF PART IV. Of Compound Colours. In treating of the several colouring matters noticed in the former parts of this work, I have most frequently mentioned the applications of which their simple colours are susceptible, in order to form what are justly denominated compound colours ; because (unlike the former) they may be composed by separate mixtures, of two of the three primitive ones, yellow, red, and blue ; yellow and blue forming a green ; yellow and red, an orange ; and red with blue, a purple, or violet, according to the proportions in which they are mixed ; whilst black, though in dyeing upon wool it may be produced by a very great accu- mulation and condensation of the blue alone, (as an orange may, by the like accumulation of yellow) is often a compound of all the three pri- mitive colours. But, notwithstanding the mention which I have thus made of the compound colours on different occasions, it seems expedient that I should advert to some of them more particularly, before this work is brought to its conclusion. PERMANENT COLOURS. S77 In dyeing compound colours, the matter which affords one part of the compound, will commonly fix itself upon the stuff to be dyed in parts not occupied by the other component colouring matter; but this sort of arrangement does not hinder the effect intended to be obtained, of an apparently uniform, equal, and homogeneal, com- pound colour, though it leaves each of these colouring matters without any benefit or support from the other, in regard to its stability or perma- nency ; and it is, therefore, always found, that a fugitive colour is not rendered less fugacious by being employed conjointly with one which is lasting ; e.g. a fugitive yellow does not acquire sta- bilityby its mixture with an indigo blue ; the green resulting from this mixture being found to lose its yellow part in some degree, whilst the blue re- mains ; and this is one of theinconveniencies which attend compound colours ; for as they are pro- duced from colouring matters, differing very con- siderably in their ability to resist the impressions of sun, air, &c. they commonly fade unequally, and thus sometimes produce an unsightly appear- ance. 378 PHILOSOPHY OF CHAP 1. Of Orange, Green, Purple, arid Violet Colours, and their various intermediate Shades or Mixtures. ft Cettee partie dc la teintnre est celle on les lumieres de I'artiste peuvcnt etre le plus utiles, pour varier ses procedes, et pour parvenir au but qn'il se propose par la voic ta plus simple, la plus courte et la moins dispendieusc ••." Berthou.et, torn. ii. 302. ART. I. Orange, $c. In several chapters of this work, particularly those which relate to the application of cochineal, quercitron bark, and madder, I have noticed the ways and means by which the various shades of colour, resulting from the mixture or combination of red and yellow, might be produced upon wool and woollen stuffs. It is, indeed, most easy, by combining the cochineal and quercitron bark in different proportions, with the preparation, or mordants employed in dyeing scarlet, to obtain all the possible shades of colour between the rose and the yellow, with their utmost vi/acity and beauty, and with sufficient permanency. Some of these, which are but a few degrees or PERMANENT COLOURS. 379 shades more yellow than the scarlet, may be ob- tained by employing a portion of either madder, or rubiamanjit'h, with cochineal, instead of the quercitron bark ; and on the other hand, where nothing higher than the orange is wanted, this may be obtained with great beauty and perfection, merely by an accumulation of the quercitron yellow, upon the basis of tin, as mentioned at p. 128, of this volume. Where shades of orange are wanted, without their utmost vivacity, upon wool and woollen cloths, they may be obtained, by combining the colouring matter of either madder or manjit'h, with that of weld, or of quercitron bark, upon the aluminous basis. In this last case, after pre- paring the wool or cloth as usual with alum and tartar, it is commonly thought best to apply the red first, and afterwards the yellow, in a separate bath, at least if the red part of the colour is to be applied in a greater proportion than the yellow. As neither cochineal nor the tin basis can be advantageously employed to dye linen or cotton, it is expedient for these substances to rely solely upon that of alumine, and to select the red co- louring matter from those mentioned in chapters three and four, of the preceding, or third part, (especially madder) combining it with the yellow either of weld, quercitron bark, or morus tine- 380 PHILOSOPHY OF toria, in such proportion as will suffice for the colour wanted. ART. H. Green. In the chapter relating to the quercitron bark, 1 have sufficiently noticed its application for pro- ducing, with indigo, all the different shades of green* upon wool, silk, linen, and cotton ; and as the blue from indigo is always a component part of this colour, I can have nothing to add here upon this subject, but what relates to the substitution of other yellow colouring matters for that of the quercitron bark, particularly those of weld, and dyers' mulberry, called, improperly, old fustic. The latter of these, as I formerly men- tioned, has been commonly preferred for dyeing Saxon greens, because its yellow colour is of all others the least depressed by the acid of the sulphate of indigo ; but this motive does not appiy to those greens, the blue part of which is * The veg3tabte productions of the earth, are principally adorned or distinguished by this pleasing colour j and so are many of the animal; particularly birds, fish, reptiles, and insects ; and though it has not been allotted by nature to man- kind, they have long been accustomed to clothe themselves in it. By the followers of Mahomet, it is, indeed, the most venerated of all colours, as yellow is in China ; and the more it partakes of this last colour, by so much is it the more lively and gay. PERMANENT COLOURS. 381 first communicated by the indigo vat, and the yellow by a subsequent dyeing with weld, quer- citron bark, dyers' saw-wort, &c. The latter of these is, indeed, in one respect to be preferred for this use, because its yellow naturally inclines to green. When greens are dyed in this way, (i. e from the indigo vat,) the blue part of the colour is most permanent, and the yellow first decays, but the reverse happens with Saxon greens. Dyers are frequently required to superadd a brown colour to the green, as in that which is called bottle green, and this may be well done by em- ploying a little logwood and sulphate of iron, with the yellow and blue colouring; matters. In dyeing silk green from the indigo vat, it is commonly thought best to apply the yellow Jirst, and to prefer that which the saw-wort affords. To dye beautiful greens upon cotton, Chaptal recommends that it be first dyed of a sky blue colour, from indigo dissolved by potash and orpiment, then macerated in a strong decoction of sumach, then dried, and soaked in the acetate of alumine, dried again, rinced, and finally dyed with quercitron bark ; employing twelve pounds of the latter to fifty pounds of cotton. He prefers the quercitron bark to weld for this pur- pose, because the colour of the latter does not combine so well with sumach, as that of the bark. (See Berthollet, torn. ii. p. 316.) ■BBBBH 382 Philosophy of ART. III. Purple and Violet. These colours, with all their shades or varia- tions, may be produced permanently, and with much vivacity upon wool or woollen stuffs, by combining the rose or crimson of cochineal with the blue of indigo ; and they may be ob- tained with even more vivacity, but less perma- nency from either logwood or orchall, as men- tioned in the first and third parts of this work. To dye cloth of a purple or violet colour, a light blue, proportioned to the depth of the co- lour intended to be compounded with it, is first dyed by the indigo vat, and being alumed by the usual boiling with alum and tartar, it is afterwards dyed with cochineal, employing from half to two-thirds of the quantity required for scarlet, according to the shade of purple or violet intended to be produced. Lilac and other light colours of this sort, may be produced by employ- ing these means more sparingly, and by taking advantage of the remnants of colour in the baths employed to dye full violets or purples. Pcerner recommends the sulphate of indigo, instead of the indigo vat, as affording a brighter blue, for producing purple and violet colours ; but the blue so obtained will have less stability than the PERMANENT COLOURS. 383 other, and be liable to fade, in some degree, be- fore that part of the coiour which is derived from cochineal. In making this use of the sulphate of indigo, Pcerner begins by preparing the cloth with alum, then dyes it with cochineal, and more than an equal weight of tartar ; and afterwards, adds the sulphate of indigo to the same dyeing liquor, and continues the boiling one quarter of an hour longer. It can hardly be necessary for me to observe, that in each of these ways, the cochineal colour will only be united to the aluminous, and not to the tin basis ; and, consequently, that it can only produce a crimson, of much less vivacity than the rose colour which it would afford with a nitro-muriiate of tin. But this last mordant has been always avoided in dyeing the purple and violet colours with indigo, because the nitric acid would unavoidably injure the indigo blue. But since my discovery of the utility and facility of employing the murio-sulphate of tin with cochineal, as men- tioned at p. 483 of my former volume., this obstacle to the use of a tin basis, for producing purples and violets with indigo, can no longer exist, the muriatic acid having no power to act upon that substance, nor, indeed, the sulphuric, when so much diluted; and my experiments have proved, that the colours in question may be dyed by thus substituting the tin for the aluminous basis, 384 PHILOSOPHY OF wi>h an increase of beauty and vivacity, espe- cially if the blue part of these colours be dyed :~. > n a sulphate of indigo instead of the blue vat. Some varieties of purple and violet may be pro- duced by substituting madder for cochineal ; but though lasting, they will be less beautiful. Silk, previously dyed blue in the blue vat, being mace- rated in the murio-sulphate of tin sufficiently diluted, may be made to receive a fine and lasting purple or violet, according to the shade of blue previously communicated, by dyeing it with cochineal. At present, however, these colours are usually produced upon silk, by first giving it a crimson colour from cochineal upon the alumi- nous basis, and then passing it through a weak indigo vat, the sulphate of indigo being more fugitive upon silk than upon wool. ^ Orcliclla, and, also Brasil wood, with the indigo blue, are frequently employed to produce purple and violet colours upon silk, but when so pro- duced, though very lively and beautiful, they have but little stability, except in the indigo part of the colour. Silk impregnated with the alumi- nous basis, or that from the nitro-muriate, or other solutions, of tin, may be made to receive different shades of purple and violet from log- wood, though the colours so produced will not prove lasting. Cotton macerated in a decoction of galls (em- ploying one pound of the latter to six pounds of PERMANENT COLOURS. 385 the former,) then dried, and afterwards soaked in a saturated solution of equal parts of alum and sulphate of iron, being dried, rinced, and dyed with its weight of madder, will obtain a fast colour, which, by varying the proportions of alum and of sulphate of iron, may be made to incline more or less to the purple or violet j and it may be rendered more bright, by boiling it afterwards for a quarter of an hour, in a weak solution of soap. An acetate or pyrolignite of iron, may be substituted with advantage, for the sulphate of that metal. Violets and purples still more durable, may be given to cotton prepared and dyed as for the Turkey red ; with this difference, however, that to the alum steep, or mordant, a portion greater or lesser of sulphate of iron is to be added, ac- cording as the colour is wanted to partake more or less of the dark or violet shades. Cotton which has received a light indigo blue, may also be made purple or violet, by impreg- nating it with the aluminous basis, and dyeing it with rraadder, as formerly -directed. Besides these results of the several binary com- binations of the primitive colours, a much greater variety of tints, (for many of which there are no proper names in the English lan- guage?,) may be composed, by uniting them all in different proportions. Of these Poerner has given numerous illustrations and explanations, to vol. II. c c ■ 386 PHILOSOPHY OF which I must refer those who desire more information respecting them, especially as it would be impossible for me, by English words, to convey accurate ideas of the effects of most of these mix- tures ; and, moreover, as the dyer in making them, will derive much more advantage from his practice, than from the theory of this art. Many, indeed, of these variations of colour may be cheaply and expeditiously obtained, by turning or saddening other colours, already described ; for which purpose, several of the earthy and metallic solutions, (and especially the sulphate of iron,) with the different acids, alkalies, &c. are com- monly employed, and frequently assisted by log- wood, galls, sumach, walnut-rinds, &c. by which an almost endless variety of changes may be pro- duced. Some of these have been already noticed in the former parts of this work, and others are known to practical dyers ; to whose experience and judgment I must commit this part of my subject, which would otherwise produce an incon- venient extension of my work. PERMANENT COLOURS. 3sr CHAP. II. Of the Black Dye, and of the common Writing Ink j as connected therewith. " Notliing more is requisite for producing all the variety of colours, and degrees of refrangibility, than that the rays of light be bodies of different sizes ; the least of which may make a violet, the weakest and darkest of the colours, and the most easily diverted, by refracting surfaces from the right course ; and the rest, as they are bigger and bigger, may make the stronger and more lucid colours, blue, grce» > yellow, and red, and be more and more difficultly diverted." Newton, Optics. Query 29th. An object, if any such existed upon or above the surface of the earth, which neither reflected nor transmitted a single ray of light, would be abso* lately invisible, and incapable of exciting any sensation or perception of colour. That which is denominated black, therefore, does not result from a total absorption, or retention, of the seve* ral rays, or a complete obstruction of their motions ; but from a very scanty and feeble trans- mission or reflection, principally of those rays which are dark coloured ; consequently, the black- est objects are those which absorb or intercept the greatest proportion of these rays, and especially of those whose colours are most lucid ; perfect blackness approaching, or being related most nearly c c 2 388 PHILOSOPHY OF to the total absence of all colour, and yellow being of all colours the most remote from black. This absorption or interception of the rays of light, so far as it is necessary to produce black- ness, may be effected in dyeing and painting, by a great accumulation and condensation of all the primitive or simple colouring matters in union with each other ;* and even by such an accumu- lation and condensation of particles, which, while * It was in this way that those once famous dyers, of the name of Gobelin, at Paris, were accustomed, for many years, to dye their finest and best Hacks. They began by giving to their white cloths a deep blue ground from the ivoad vat, and afterwards boiled them in the usual way, with alum and tartar, and then dyed them with madder and weld, which, upon the aluminous basis, produced a red and yellow in addition t© the blue ; .aid from this combination of these three primitive colours, a very durable black resulted, which, having been produced without iron, must have been exempted from the rottenness which the oxides of that metal h?.ve been generally supposed to occasion. From this combination of colours, no more than a very snaring transmission or reflection of coloured rays could result ; as the woiid ground would only reflect or transmit those of a blue colour, which last the madder red would either absorb or intercept ; and the weld yellow would do the same in regard to the red proceeding from the madder ; which red, in conjunction with the woad blue, would permit but a very few rays to escape from the weld yellow. Such an obstruction or retention of the rays of light gcnerully, must, of necessity, give the effect or appearance of blackness 5 an effect similar to that which painters produce by mixing their blue, red, and yellow pigments, in suitable propoi lions. PERMANENT COLOURS, 389 dispersed, could only produce a single dark colour, particularly the blue or violet, though a mixture and condensation of two colours may render the black more intense* This sort of accumulation or condensation, is produced more easily upon wool than upon linen or cotton, and more easily upon the latter than in a fluid mixture.! There are, however, several animals and vege- tables possessing colouring matters, which, by mix- ture with solutions, or other preparations, of iron, in certain states of oxydation, immediately pro- duce a black liquid, as is seen in the familiar instance of common writing ink ; and as the black dye, in most general use, depends chiefly upon a combination similar to that by which ink is pro- duced, it seems proper that we should more par- ticularly consider this latter production, which * A sufficient proof and illustration of this may be seen at p. 233 of my former volume But the sulphate of indigo, which, as is there stated, produced a very perfect black on woollen cloth, by mere accumulation or condensation, will not, without additional means, produce a similar colour on linen or cotton. T A proof of this may be &en, by adding any, even the most oxygenated solutions or oxides of iron, to the infusions or decoctions of madder, when it will be found, that such additions will produce nothing darker than a tobacco or coffee brown. But if linen or cotton be sufficiently impregnated with an acetate or oxide of iron, and dyed with madder, a full and permanent black will be the result, and it is in this way that the most durable black of the calico printers is produced. 390 PHILOSOPHY OF happened to engage my attention so early as the year 1770; when opinions demonstrably erro- neous respecting it, were promulgated aid be- lieved, as they have since been, by the greatest chemists and philosophers of their limes. According to one of these opinions, (then uni- versally admitted, and still subsisting) the pro- perty manifested by galls, and many other vege- tables, of producing a black ink, or colour, with sulphate of iron, was ascribed solely to another property, denominated astringency, of which the former was assumed to be, both the measure, criterion, and prooj.* But as this opinion neces- * Evidence of the prevalence of this opinien at that, as well as at subsequent periods, may be found in book-, of the highest authority. Dr. Lewis, in his Philosophical Commerce of Arts, a work of great merit, considering the time at which it was published, when treating of the production of ink by galls and sulphate of iron, adds, that "the power by which vegetables produce this blackness, and their astringency, or that by which they contract on inimal fibre, and by which they contribute to the tanning of leather, seem to depend on one and the same principle, and to be proportioned to one another." Dr. Cullen also, in the Jirst edition of his Materia Medica, (p. 177, 4to.) states as one characteristic of astringents, that their '-' de- coctions thrown into a soluiion of green vitriol, strike a black colour and form an ink;" and that those "which give the blackest ink, provided they are not accompanied with any pecu- liar acrimony, which discharges their use as astringents, may be reckoned the strongest and best." The celebrated JMacquer also, in his Art de laTeinture en Soie, printed in folio, under the sanction of the Royal Academy of Sciences at Paris, says, PERMANENT COLOURS. 391 sarily produced fallacious conclusions in regard both to the chemical and medical powers, or effects, of a considerable number of vegetables, I thought it my duty to contest it ; and this I did, in a communication which was read to the Royal Society, at one of their meetings in the month of May, 1773; in this, among other things, I asserted, that there were a considerable number of vegetable matters, which, though they decidedly manifested strong astringent powers, were, as I had found by repeated experiments, absolutely incapable of producing any degree of blackness, properly so called, by being mixed with sulphate of iron ; and, on the other hand, that there were other vegetables in which no astringent 'power was discoverable, though they copiously produced a black colour, when mixed with this sulphate. I alleged various instances of each of these sorts of vegetables in support of my assertion,* " Engeneral tonte teinture noire est composee pour le fond, des ingredients avec lesquels on fait l'encrea ecrire ; c'est tousjours du fer dissont par des acides, & precipiie par des matieres astr'mgentes vegetales." Much more evidence to this effect might be adduced ; if the fact intended to be established by it were not so notorious, as to reuder it unnecessary. * It will, probably, be thought sufficient for me here to men- tion the following as instances of these several sorts of vege- tables, viz. Among those which are most decidedly astringent or acerb, but incapable of producing blickness with iron, are 1st. The bark of the quercus nigra, Lin. or quercitron bark, 392 PHILOSOPHY OF and, as I believe, sufficiently demonstrated, that, though the so called astringent vegetables, do lately described : its taste is strongly astringent j it efficaciously coagulates and precipitates glue, and is generally employed in North America to tan skins, which it does speedily and effec- tually, though its decoction or infusion will not produce any thing more than an olive brown or drab colour with iron, in any state of solution or oxidation j nor is it capable of dyeing a black colour with that basis, by the greatest possible accumula- lation or condensation even upon wool ; as I know by the re- sults of many trials. 2d. The bark of the rhizophora mangle, or red mangrove, also lately mentioned, which manifests great astringency to the taste, precipitates glue expeditiously and copiously, and tans skins very speedily and efficaciously, being generally preferred and employed for that purpose by the Spaniards in different parts of America ; but, like the quercitron bark, it is utterly incapable of producing a black ink; or dyeing a black colour, with any solution or preparation of iron, even though accumu- lated and condensed upon wool, by long boiling therewith. — Mahogany bark possesses astringent and other properties ex- actly similar to those of the mangrove bark, and, like the latter, it is incapable of producing a black with iron. 3d. The extract of the mimosa catechu, formerly called terra japonfca, and by Linnaeus erroneously supposed io hfive been obtained from that species of palm which produces the areca nuts, and which he, therefore, denominated areca catechu. There are two varieties of it, one imported chiefly from Bom- bay, and the other from Bengal j but, though differing in ex- ternal appearance, they manifest the same properties. Boih of them are highly astringent, though a little sweetish to the taste 5 and both have been found by Sir H. Davy and Mr. Purkis, of Brentford, to tan skins most powerfully ; but neither is capable of producing a black ink, or dyeing a black colour, PERMANENT COLOURS. 393 lany of them possess matters capable of produ- ing blackness with iron, (in a suitable state of with any, even the most oxygenated preparation of iron. This I assert, from the results of experiments repeated many times, not only with parcels of this drug as .sold in the shops, but with some choice specimens which 1 received from Dr. Roxburgh, the late Mr. Tiberius Cavallo, and others; of which no one, in a single instance, was found to produce any thing darker than a snuff' colour, with tlie most oxidated sulphate of iron, even that to which nitric a< id had been purposely added, to increase., (as it does with galls) the blackness resulting from its application. I have asserted these facts more distinctly, and in stronger terms than 1 should have thought necessary, had not Sir H.Davy, in the very lucid and judicious account which he gave to the Royal Society, of his experiments and observations on the constituent parts of astringent vegetables (published in the Philosophical Transactions for the year 1803), after admit- ting that "the least oxygenated sulphate of iron produced no change in the infusion" of catechu, stated (at p. 255) that " with the most oxygenated sulphate, it gave a dense Hack precipitate, which, when diffused upon paper, appeared rather more inclined to olive than the precipitate from galls :" and had he not also stated (at p. 258) that an aqueous solution of the pure extractive matter of catechu being added to the solution of oxygenated sulphate of iron, it communicated a fine grass green tint ; and that a gteen precipitate was deposited which became Hack by exposure to the air." Before these statements fell under my observation, I had made, probably, fifty experiments with mistuvesof catechu and iron in different states of oxyge- nation, which were begun in the hope that the former, from its moderate price, might be found capable of being advantage- ously employed upon a large scale, in producing a prosu/stanlivc black for calico printers j bin I had completely laid it aside, with the fjjltest ceaavictwn, that • could not be made to produce any thing like, or even approaching to a black colour, by or 8JM PHILOSOPHY OF oxidation) they do not possess it exclusively, but in common with other vegetables which are with any preparation of iron whatever. In consequence, how- ever, of these statements by Sir H.Davy, I was induced to renew my experiments, and with a greater variety of specimens of the catechu j but from none of them could I produce, by any degree of oxidation given to the iron, or any subsequent ex- posure of the mixture to the air, any thing darker, when dif- fused on paper, than the snuff colour already mentioned, which, to my apprehension, is very far removed from black. Whether the catechu employed by him was adulterated, or whether, from believing that according to the general opinion, this sub- stance as an astringent must produce blackness with iron, he was led to employ expressions exceeding the effect really produced, I know not — but there seems to have been a want of Sir H. Davy's usual accuracy in these statements, particularly when he describes the dense black precipitate from catechu as appear- ing, by diffusion upon paper, " rather more inclined to olive than the precipitate from galls." — Probably no person ever made more precipitates than I have done from mixtures of iron and infusions of galls ; and I do not recollect that any one of them ever inclined to olive, though, by varying their proportions, a variety of shades or tints may be produced between a reddish brown black, and a bluish or violet black — the former occurring when the galls are in excess, and the latter, with an excess of iron or its oxide. • But how an olive could result from any such mixtures I know not. Of the vegetables which manifest no astringency, though they abound in colouring matter, which produces a black ink, and black precipitates with iron, the following instances may suffice, viz. 1st. The bark of juglans oblonga alba, white walnut or butter nut of North America, of which the decoction very decidedly and copiously affords a black ink with sulphate of iron, and PERMANENT COLOURS. 395 destitute of astringency ; and that this last pro- perty, therefore, is not necessarily or constantly connected with, or denoted by that of producing a black colour with iron, or any of its prepara- tions. strongly communicates that colour, by dyeing, to wool, silk, linen, and cotton, though it discovers no astringency to the taste, nor causes any precipitation with gelatine. 2d. Logwood, or its decoction, which is sweetish, but not in any degree acerb to the taste, nor capable of producing the slightest precipitation with glue, (until by long keeping, it has acquired new properties, as stated at p. 341 of this volume) and yet its abundant power of producing a black ink, and of dyeing that colour with iron, has long been notorious. The fact, indeed, of its possessing this power has induced physicians to suppose, that it must bean astringent, and to employ it as such medicinally — which is one proof of the errors resulting from the groundless opinion here controverted. 3d. Brazil wood, and the several other species caesalpinia, lately mentioned, the decoctions of which are completely destitute of any thing like an astringent, austere, or rough taste, and of even the slightest power of occasioning a preci- pitation with gelatine ; and yet, like logwood, they copiously afford a very black ink with iron, and dye that colour with sulphate of that metal. Other and similar instances might be found in madder, galium, &c. which notoriously afford most permanent blacks, even upon linen and cotton, with iron, though they are com- pletely destitute of astringency and of the tanning principle. The like instances may also be found in the animal kingdom, particularly in the cochineal insect, which, with sulphate of iron, produces a deep black ink, and a black dye, though it has never been found to possess the least astringency. Z96 PHILOSOPHY OF At that period, the rottenness which was gene- rally complained of as attending black cloths, had been ascribed to the acid part of the sulphate of iron, employed to dye that colour,* and this acid, being also supposed to accelerate the decay of writing ink, I was induced to endeavour to effect a direct combination of iron with the solu- ble part of galls, without the intervention of any acid; and for this purpose, having made a decoc- tion of galls, I put to it a quantity of clean iron filings, and, in a little time, perceived that this mixture occasioned the production of a consider- able number of air bubbles, and an escape both of inflammable air and carbonic acid gas, together with a brownish discolouration upon its surface ; which discolouration continued to increase, as well as the extrication of hydrogen and carbonic acid gases, for the space of twenty-four hours ; when the mixture had acquired a decidedly full black colour on its surface, though internally it * That I may net multiply proofs of this well-known fact unnecessarily, I shall content myself with the following extract from M. Macquer's Art de La Teinture en Soie. — viz : " Ce qu'il y a deplus essentiel a observer sur la teinture noire, e'est qu'on general, elle altere et enerve beaucoup les ttoffes ; ensorte que celles qui sont teintes en noir, sont tousjours beau- coup plustot usees, toutes choses egales d'aillieurs, que celles que sont teintes en d'antres couleurs: C'estprincipalmentaJ' acide vitriolique de la caperose, lequel n'est que imparfaitment s;ature par Le Fer, qu'on doit attribuer cet inconvenient." Other and similar proofs will occur speedily. PERMANENT COLOURS. W appeared, upon examination, to be only of a brownish purple ; but, being applied to paper by a pen, it soon became black, by an absorption of oxygene. This was in the summer season, and the decoction of galls having been left to act upon the iron filings twenty-four hours longer, I judged, from its appearance, that a sufficient solution and combination of iron had taken place, and, there- fore, separated the fluid part, by a strainer, from the iron filings ; and by exposing the former in an open vessel, I found the next day, that it was become deeply black, and that (being applied to paper with a pen) it was capable of answering the purpose of ink extremely well. Having repeated this experiment several times with the same result, I employed this direct combination of the colouring matter of galls with iron, as a dye to wool, silk, and cotton, and found it to pro- duce a good black upon each of these substances ; and I, therefore, thought myself warranted to conclude, in opposition to what had been alleged, particularly by the late Dr. Percival, (in his Essays Medical and Experimental, and especially from his Experiments 37 — 39) that the sulphuric acid was not an essential constituent part of ink, or of the black dye, but that both might be produced, and, as I thought, with advantage, by directly combining the soluble part of galls with iron. And these conclusions, together with the experiments from which they had SBBBBBBB 398 PHILOSOPHY OF been drawn, were likewise stated in the com- munication which I made to the Royai Society, as lately mentioned ; but as I then announced my expectation of speedily adding to it a far- ther account of the benefits to be derived from the application of this discovery * to the purposes of dyeing, the Committee of Papers thought proper to wait for that addition, be- fore they decided upon the publication of my first communication ; and having waited in vain, until the 3rd of March, 1774, the late Mr. Walsh, then a member of the council, on that day wrote me a letter (which is now before me) requesting in their behalf, to know my " intentions about giv- * Dr. Lewis, though he had completely adopted the opinion which I recently mentioned, of the real or supposed injurious effects of sulphuric acid, as a constitutional part of ink, and of the black dye, and though he made trials of iron dissolved by other acids, instead of the sulphate of that metal, without any benefit, as he conceived, yet he did not attempt to effect a combination of iron directly with a decoction'of galls. Such an attempt was, however, made afterwards by the late Dr. Percival, but as he employed a cold infusion of galls, and, probably, in cold weather, without allowing sufficient time to obtain the desired effect, his experiment f.iled, and he con- cluded this direct combination must be impracticable. It was, I however, effected by M. de Morreau, and his associates of the Academy at Dijon, about the year 1778, Jive years subse-l quently to my communication to the Royal Society on this subject ; of which, however, it may be presumed, that these I academicians wete ignorant. PERMANENT COLOURS. 399 ing an additional paper to the society on the sub- ject of colours, the Committee of Papers having deferred the consideration of that of the last year in the expectation of such a paper." In answer to this letter, 1 informed Mr. Waish that it was still my intention soon to finish, and send to the Society the additional paper in question, and also intimating, that as the Committee had waited so long for 5t, my desire was that they should con- tinue to do so. After this, circumstances occur- red, of which a detail would now be useless, to hinder mie from fulfilling the intention so declared ; and this additional communication having never been madie, no notice was, of course, taken of the first, in the Philosophical Transactions ; and, con- sequently , the errors which it was intended to correct were left to subsist, as some of them do, at this time. The ink, formed by this direct mixture of iron- filings wiith the soluble parts of galls, when they were comibined in suitable proportions, was found, if employed within a few weeks after being made, to produce upon the paper a very smooth, full, and lasting black ; but when long kept, it did not fulfil my expectations, as it seemed even more disposed than common ink to become mouldy, and also to concrete and subside in the form of a black powder ; defects which, in common iiik, probably are, in some degree, obviated by the influence of sulphuric acid j for though this acid 400 PHILOSOPHY OF may, as is supposed, accelerate the decay of ink after its application to paper or parchment, as, in old writings, it probably retards the commence- ment and progress of mouldiness, whilst the ink is in a liquid state, and enables the water for a longer time to hold in a state of solution or sus- pension, the black compound of oxj dated iron and the colouring matter of galls, which, if their affinities are not counteracted by sulphuric, or some other acid, will unite more closely and exclu- sively, and by detaching themselves from their aqueous solvent, will subside like charcoal finely powdered; an inconvenience, indeed, to which common ink is, in some degree, liable, and more especially when it is either much diluted, or not sufficiently gummed. When the decoction of galls, and the iron filings, were mixed and left together, until an excessive proportion of the latter had been dis- solved and combined with the former, the black compound appeared still more disposed to con- crete exclusively, and subside in large particles ; and if, by shaking, these were again diffused through the water, whence they had subsided, and applied by a pen to the surface of paper or parchment, they did not, in the smallest degree, penetrate the substance of it, like commen ink, but, when dry, might be rubbed off, as if pow- dered charcoal only had been applied. They were, indeed, easily made soluble in wa:er, by PERMANENT COLOURS. 401 adding to it a sufficient portion spf sulphuric acid ; but this only produced a mixture similar to the common ink, wh n made with an excess of the sul- phate of iron. And, after many triata I found that the best expedient for rendering ink useful, when produced by a direct mixture of iron-fitJQgs with a decoction of galls, was that of combin!^:? the latter with only so much of the iron as was barely sufficient to produce a black colour, when the mixture had become sufficiently oxygenated. By this sparing use of the iron, and the addition of a suitable proportion of gum, the deposition of black matter was, in a great degree, obviated, and the ink, from specimens which I have pre- served of it, has appeared to be very lasting, at least if employed before it had suffered by long keeping in a moist state, in which it was still liable to become mouldy, perhaps more speedily than ink made with the sulphate of iron. Delaval has, however, greatly commended ink formed by this direct mixture of iron-filings and the decoc- tion of galls, (though without acknowledging the inventor) ; and Proust, as Berthollet observes, (tom.i. p. 126,) has given a decided preference to such ink. Some years after my communication to the Royal Society, Scheele, by exposing a cold infu- sion of galls ico the open air during a whole sum- mer, obtained from the residuum, which *had be- come almost dry, (by dissolving it with hot water, vol. ii d d 402 PHILOSOPHY OF filtering, and ajgaih evaporating) a crystallized salt, which, v.'hen added to a solution of the sul« phate of irc, ri) ma de it black like a decoction of galls. Tnis salt, which has since been denomi- nated, gallic acid, Scheele supposed to exist ready formed in the gails,butto be so intimately combined with some mucilaginous or other matter, as to be incapable of crystallization, by the ordinary means, or without some internal movement or change, like that which occurs during fermentation : and this supposition has been since generally adopted by chemists, who have attached great importance to Scheele's discovery of the so called gallic acid, and attributed to it all those properties, which have been thought to characterize and distinguish that class of vegetables, commonly called astrin- gents 5 though they have, as I think, done it most unwarrantably, because Berthollet and others have all failed in their numerous attempts to obtain this acid from even a single one of this class of vege- tables ;* and not being found or contained in them, we cannot be justified in taking it as the * See his Elements, &c. torn. i. p. 108, &c. Davy (see Philosoph. Transactions for 1803, p. 268) was disappointed in his expectation and endeavour to obtain gallic acid from the fruit of the terminalia chebula, or yellow myrobalans, which, by my experiments, have appeared to afford, when the nut was removed, nearly as much of that colouring matter which pro- duces a black with iron, as the best Aleppo galls, and to produce this colour ai efficacirusly, perfectly, and permanently, even upon linen and cotton, with the several preparations o ; iron. PERMANENT COLOURS. 403 exemplar and evidence of their properties. There is, indeed, so far as I can judge, good reason to believe, that this gallic .icid has no natural existence any where, and that it is a production of art, or, perhaps, more strictly a modification of the acetic, or other acid, to which astringents are principally indebted for their acerbity. That an important modification of this acid should take place, during the long continuance of Scheele's process, might well be expected, especially as he has himself sta- ted considerable changes to have occurred in re- gard to the infusion of galls from which it was obtained, and which had not only become very mouldy, but was covered by a mucous pellicle, and had lost all its styptic taste, a considerable time before the operation terminated, When, in addition to Scheele's discovery. Seguin had taught us how to recognize or ascertain the tanning principle in vegetables, by mixing glue with their infusions, or decoctions, attempts were made to sieparate the latter from the gallic acid, and obtain each in a distinct and pure form. Among the means employed to effect this sepa- ration, those recommended by Proust, and which depend chiefly upon the muriate, or nitrp-mu- riate of tin, (see Ann. de Chimie, torn. 25 and 41 .) seem to be most efficacious, though they are ad- mitted to be insufficient ; the gallic acid, after such separation, always retaining a little of the tanning principle, and the latter a little of the acid, d d 2 404 PHILOSOPHY OF I have given some account, in the preceding chapter, of the origin and constituent parts of galls, to which I must refer my readers. From the cause and manner of their production, we might naturally expect that they would only con- sist of matters, afforded by the juices of the oak on which they grow ; which juices, in conse- quence of the stimulus given by the larva of the gall-fly to the adjacent vegetable fibres, circulate and accumulate more copiously than they would otherwise do, around the offending insect, by a sort of inflammatory process, like that which is produced by a thorn in human flesh ; and, there- fore, though these vegetable excrescences might contain some matters derived from the oak, in a more distinct and pure state than that in which they are naturally produced by the tree itself, they could contain no matter which the tree had not produced, unless it were afforded by the insect. But the latter is not known, so far as I can discover, to possess any matter capable of producing a black with iron, and even if it did, we might reasonably conclude, that it must have been imbibed or derived from the juices of the oak, which notoriously contain it ; and, th ere- fore, though galls confessedly contain both tan- ning and tingent matters, in a more cimcentrated and pure state than that in which the oak affords them naturally, it may be presumed, that in every other respect they are the same identical PERMANENT COLOURS. 405 matters ; even though it should be true, as M. Chaptal supposes, that galls possess something of an animal nature, (which, indeed, they must do, if employed before the insect has escaped from them). For unless it were proved, that the insect possessed, and could impart to the galls some tin- gent matter peculiar to itselfcand similar to the sup- posed gallic acid, there is no reason tosupposethatthe animalu2k.tuYQ of the gall fly, or its larva, would ma- terially change the properties of either the tanning or colouring matters naturally produced by the oak; and we are warranted in believing, that in fact no such change is produced by this insect, because M. Berthollet states that, by his experiments, the white galls (from which the larvae must have escaped) appeared to yield more of the gallic acid than the blue galls, which always retain the insect* (See Elements, &c. torn. i. p. 108, &c). And as he also states, that he had not been able to detect amy gallic acid in oak bark, we have an additionail reason for believing, that this a:id is not a natural production; more especially as, since different ways of procuring it have been made known,* its properties, as BouilLon La Grange has remarked, are found to diffei accord- ing to the method in which it has been obtained. * One of these additional ways, not yet men 1 ' .ed, is that- discovered by Deyeux, of distilling the precipitate of an ^fu- sion of giihs, made with carbotuitt- of p >tash, bj which a very small proportion of this acid may be obtained. 106 PHILOSOPHY OF (See Ann, de Chimie, torn. lx. p. 156). Many new names and distinctions among the acids have, in- deed, been introduced within the last forty years, founded only upon trivial modifications, produced by art; and if my memory does not mislead me, Scheele also obtained the supposed acid of sugar, as well as gallic acid, from galls. It will have been observed, that in the preced- ing parts of this work, I have invariably applied the name of colouring matter to those pirts of vegetable dyeing drugs which are found to pro- duce colour with an earthy or a metallic basis ; and I have, certainly, never been able to discover any good reason for doing otherwise, in regard to those vegetable matters which afford ink, or a black dye, with iron ; matters which, indeed, are extremely various in their other properties, and even in the sorts of black which they produce ; though chemists have, as I think improperly, con- foundedmostof them, under the general denomina- tion of astringents ; a term which may be unobjec- tionable, as signifying acerbity in vegetables, but not as indicating, or being invariably connected with, any such property or matter as they have been supposed universally to possess, that of producing a black colour with iron. The tanning principle, if it deserves to be called a principle, notwithstanding its varieties, is found much more constantly in the acerb or astringent vegetables, than the colouring matters producing PERMANENT COLOURS. 407 black with iron ; and this last is very frequently united with tannin, but not invariably, as we have lately seen by the facts stated in regard to the catechu, and other matters employed for tan- ning. M. Berthollet has appropriated an entire chapter to the subject of astringents, (des astringents) which name, says he, designates a property common to a great number of vegetables, (" une propriete commune a un grand nombre de vegetaux") : he confesses, indeed, that there is no other property in them, concerning which people have been satis- fied with such vague ideas ; nevertheless, continues he, every substance which renders a solution of iron black, has been commonly deemed astringent, or acerb ;*andthiseflect has beenattributedtoor^Vfeft- iical principle, residing in the substances produ- * Sir H. Davy (probably from what he saw in his experi- ments with catechu) seems to have endeavoured to amend the common definition, or notion of the properties of an astrin- gent, or rather of the gallic acid. "The presence of tannin," says he, " in an infusion, is denoted by the precipitate it forms with the solution of glue or of isinglass : and when this principle is wholly separated, if the remaining liquor gives a dark colour, with the oxygenated salts of iron, and an im- mediate precipitate with the solutions of alum and of muriate of tin, it is believed to contain gallic acid and extractive mat- ter." Phil. Trans, for 1 803, p. 234. By this substitution of a dark, for a Hack colour, as a criterion of the presence of gallic acid in an infusion, to which an oxygenated salt of iron has 408 PHILOSOPHY OF ring this effect ;* experience, however, says he, has since shewn that it is necessary to admit tico sorts of astringents, viz. tannin and the gallic acid: and he adds, that both of these precipitate iron, and produce with it a bluish black colour : (torn, i. p. 105) but this, though true of the tannin afforded by most of the oaks, is not true of that contained in the quercitron oak, or in the man- grove, &c. nor of that which chiefly constitutes the catechu, as I have already noticed, so that we find, even in this, the most recent and correct ele- mentary work on this subject, a renewed assertion of the errors, which I long since controverted, and which I am now endeavouring to overcome, by- facts, which, when properly made known, cannot been added, a foundation is laid for very erroneous conclu- sions ; there being, so far as my recollection extends, no adjective colouring matter, either animal or vegetable, which is not darkened, at least, by the oxygenated salts of iron ; and if the latter do not darken some of the sub^antive colouring matters, as that of indigo, and that of the bnccinum lapillus, it is only because these matters form no combination with the oxide of iron. " * Cependant on a regarde ordinairement comme astrin- gent, ou comme acerbe, toute substance qui change en noir une dissolution de fer ; on a suppose que cet effet etoit du a une principe identique, qui reside dans toutes les substances qui le produisent. Inexperience a fait voir ensuite qu'il falloit admettre deux especes d'astringent, savoir, le tannin, et l'acide gallique." Elements, &c. torn. i. p. $5, gQ. PERMANENT COLOURS. 40i> fail of producing more accurate opinions respect- ing these matters. M. Berthollet, after having thus arranged the tanning principle, and the gallic acid, as two sorts of astringents, proceeds (torn. ii. p. 113, &c.) to notice and compare their respective properties ; and in doing this, he represents the affinities of tannin, as differing but very little from those of the gallic acid, at least in those combinations which relate to dyeing ■> but he remarks, that the compounds of the latter, generally manifest more stability, than those of the gallic acid ; that it forms an insoluble substance with gelatine, whilst the gallic acid combines, and remains with the latter in a fluid state j and that it unites with the solutions of iron, forming a precipitate, which spee- dily reparates and subsides j whilst the gallic acid merely produces, with these solutions, a transpa- rent (black) liquor, from which the coloured particles only subside, after a great length of time, and by the aid of particular circumstances : but the most important difference between these mat- ters, presented itself in applying them to silk, linen, and cotton ; which, after being impreg- nated with the gallic acid, could not be made to take a black colour, by being dyed with any so- lution of iron ; though these substances, when treated in the same manner with tannin, obtained good blacks. Similar results happened when the iron basis was first applied to the silk, &c. and * BBBB 410 PHILOSOPHY OF the tannin and gallic acid afterwards, and from these experiments he infers, that though the gallic acid may co-operate with tannin, in producing a black by dyeing, it must be useless for that purpose when employed alone (with iron). He admits, however, that the tanning principle acts efficaci- ously in this way without the gallic acid. After this account of the most generally re- ceived opinions, respecting the gallic acid and the tanning principle, I will venture here to state my own conceptions of these matters. I have lately intimated my inability to discover any good reason for not considering the tingent part of galls, oak bark, and other vegetables, producing a black with iron, merely as a colouring matter, at least in regard to this effect, as I have done in regard to the substances which afford other co- lours ; and, indeed, it has long appeared extraordi- nary to me, that this property in oak galls should have almost exclusively engaged the attention of chemists and philosophers, whilst other vegetables, particularly the bark of the acer rubrum, and the fruit as well as galls of the chebula terrmnalia, produce a similar effect, with equal efficacy, and perfection. These vegetables, like the oak and its galls, give proofs of a considerable portion of acidity, (on which their acerbity chiefly depends,) and also of that which is called the tanning prin- ciple ; and both of these are so intimately com- bined, with what I shall continue to denominate PERMANENT COLOURS . 411 the colouring matter, that no means have yet been discovered by which either of the former can be obtained separately and distinctly from the latter ; and, therefore, it has been found invariably, that the so called gallic acid, and the tannin procur- ed from galls, were either of them always capable of producing a black ink with solutions of iron. But chemists, prepossessed by certain notions about acidity, have strangely overlooked this colouring matter, and ascribed its effects to the supposed gallic acid, as they have done in regard to the colouring matter of Prussian blue, calling it Prussic acid, with even greater impropriety, because the latter does not manifest the smallest acidity, whilst vegetables remarkable for their acerbity, do unequivocally give proofs of it ; but so far as I can discover, this, their acidity, though co-existent and united with their colouring mat- ter, is distinct from it, and useless in regard to its ting'ent effects. In Scheele's process for procuring the supposed gallic acid, the tanning and colouring matters seem t, win not in- jure the cloth, and will produce a perfect back without the aid of a blue around. I have, however, tried sulphate of copper with log- wood, not only in equal, but in various other portions, without having been able to produce any thing like a perfect black, even in appearance, and much less a black sufficiently permanent. With sulphate of iron and logwood, indeed it is not difficult to produce a full and deep bkck; but it certainly will not prove so lasting as the black with sulphate of iron and galls, or sumach, either alone, or with a moderate proportion of logwood ; which last, certainly improves the ap- pearance of the black, dyed from galls and iron, by rendering it more intense, glossy, and soft, or veloute, as it is expressed by the French. PERMANENT COLOURS. 457 All black cloths, for the dyeing of which a large proportion of logwood has been employed, may be reddened by the application of muriatic acid. Lime-water obstructs the production of a black by logwood and sulph te of iron, though a small proportion of potash favours its production. Hats are dyed without a blue ground from indigo, by galls, logwood, and sulphate of iron, and for these, as well as for woollen cloths, the vegetable colouring matters are applied Jirst, and the mordant, or sulphate of iron, afterwards, con- trary to the practice observed in dyeing other colours. A peculiarity which has been ascribed to a belief, that the sulphate of iron, if first applied to cloth, not impregnated with the vegetable colouring matter, would act more injuriously upon its fibres, than it does by a subsequent ap- plication; though the experiments which I have made do not convince me that this belief is well founded in any case, and more especially where the cloth has been previously dyed blue with indigo. Probably, the practice has arisen, though without a proper knowledge of the motive from the very little affinity which subsists between the iron contained in the sulphate of that metal and the fibres of wool, until they have imbibed a portion of vegetable matter. There is, as I stated in my first volume, a very marked attraction be- tween the oxide of iron and the fibres of linen or 458 PHILOSOPHY OF cotton ; but this oxide is much more stror.gly attracted by the vegetable colouring matter, than by the fibres of wool, and, therefore, it has been found most advantageous to impregnate the lat- ter with this colouring matter first, and after- wards to apply the solution of iron ; and even when this has been done, it is found very difficult to render white cloth black, by the mere application of galls and sulphate of iron, unless these appli- cations are made repeatedly ; though it may be done readily where the cloth has previously received a blue ground; or where the effect of the galls and iron is assisted by adding to it the purple, blue, or violet colour, of logwood. Lewis, in his Philoso- phical Commerce of Arts, observes, that " vitriol, (meaning sulphate of iron) and galls, in whatever proportions they are used, produced no other than browns ;" and that " logwood is the material which adds blackness to the vitriol and gall brown ;" but that " on blue cloth, a black may be dyed by the vitriol and galls only;" though, even in this case, as he says, the logwood deepens the colour. This observation is, however, only true, in regard to the single application of galls and sulphate of iron ; which, whether the iron or the galls be first applied, and the other superadded, will at most only produce a brownish black on white cloth ; manifestly, because the latter does not at once imbibe enough of the iron to answer the purpose; but by renewed applications of iron and PERMANENT COLOURS. 459 galls alternately, a good and lasting black may be^ obtained, without either a blue ground, or the co-operation of logwood. About the year 1753, Bergman strongly recom- mended a method of dyeing cloth black, after it had received a blue ground, by first boiling it for two hours in a bath with one pound of sulphate of iron and half a pound of tartar for six pounds of cloth, (taking care that the tartar should be all dissolved before the sulphate was added,) and, after having rinced the cloth, dyeing it in a sepa- rate bath, with a sufficient portion of the arbutus uva ursi, or bear-berry ; though this, without the blue ground, would not, as Lewis has observed, afford a black colour, unless assisted by logwood. Berthollet (torn. i. p. 126) quotes Mr. DelavaJ, as having stated, (in his Experimental Enquiry,&c.) that by a simple dissolution of iron in a decoction of gall nuts, he had not only produced the blackest and most durable ink, but that, having immersed therein both silk and woollen stuffs, without adding any acid, he had dyed them of the deepest and mint permanent black. All this, however, must have been subsequent, by several years, to my communication upon this subject to the Royal Society, of which he was a member ; and if he did not rely solely upon that communication, but actu- ally performed what is thus stated, he must have been fortunate in dissolving so exactly the pro- portion of iron, necessary to produce these excel- 460 PHILOSOPHY OF lent effects ; an operation which, after I had a first accidentally succeeded in performing it, I ound liable to so many failures, from the diiiculty of ascertaining, at any time, how much of the metal had been actually dissolved, that I have long '.eased to expect that it can ever be adopted with advan- tage by dyers.* I have mentioned, at p. 305 of my firs, vo- lume, that a fine lasting black, without inn or any other basis might be dyed upon blue :loth, from a species of lichen, called rags, or ston< rag in the North of England, (the lichenoides ptlmo- nium reticulatam vulgare marginibus peltifeis, of Dillenius); and if this could be readily an I co- piously obtained it would, probably, deserve :o be preferred to madder and weld for rendering blue cloth black ; and, indeed, I have found, tha the brownish yellow which alder bark affords upoi the aluminous basis, may, for this purpose, be advanta- geously substituted for that of weld. * The best, and, perhaps, only method of doing this, would be first to ascertain, as nearly as possible, the quantity of iron in its metallic state, which will produce the best effects when totally dissolved by, or with the soluble part of a given qiantity of galls ; but it would be highly inconvenient, and, in isveral respects, disadvantageous, to wait long enough for this conplete dissolution of the iron, unless it were first brought ino the state of iron filings ; which, for general use in dyeing >lack, would be attended with more trouble andexpence, than aiy ad- vantage to be expected from this change seems likely to bt com- pensate. PERMANENT COLOURS. 4GI Of the Application of the Black Bye to Silk. The fibres of silk not being organized like those of wool, do not so readily admit the black dye as the latter. Dr. Lewis (in his Philosophical Com- merce of Arts) observes, that " woollen and silk are both dyed of a permanent deep black, but with this difference, that what the woollen dyer effects by three or four dippings of the cloth, in his dyeing liquor, the silk dyer scarcely obtains from twenty or thirty dips." Though raw silk imbibes the black dye with as much facility as that which has been deprived of itsgurrn, yet, when dyed, the black appears less intense and less fixed in the former than in the latter ; and it is, therefore, made previously to un- dergo the usual boiling, with one-fourth or one- fifth its weight of soap, during three or four hours : by this operation, indeed, silk often loses nearly one-fourth of its weight, but this loss is more than compensated by that which it gains from die black dye. As the affinity of silk with the soluble parts of galls is greater than with the iron contained in a solution of the sulphate of that metal, it is thought most advantageous to begin by first ap- plying the former -, and for this purpose about one-half as much in weight of Aleppo galls as of Jhe silk to be dyed, is boiled in a suitable pro- portion of water, three or four hours, after 462 PHILOSOPHY OF which, the decoction having been left to settle, the fluid part is separated from the sediment, and the silk maceratedtherein twenty-four hours, more or less, according as the impregnation is intended to be more or less copious ; and being afterwards dried and slightly rinced, the silk is immersed in a solution of the sulphate of iron moderately warmed, and kept therein with the usual manage- ment, until the colouring matter of the galls has nearly saturated itself with the oxide of iron ; after which it should be rinced and immersed, &c. in a warm decoction of logwood ; and having there imbibed as much of the colouring matter as may be disposed to unite with it, the silk is to be again immersed in a solution of iron, then rinced, and again transferred to the decoction of galls, repeating these alternate immersions, &c. until the desired colour shall have been produced. — Some dyers think it expedient, or at least be- neficial, to employ, for dyeing silk black, about one-sixteenth of its weight of verdigrise, which may be either mixed with the solution of sul- phate of iron, or with the decoction of logwood. Iron dissolved by the pyroligneous or acetous acid, is, in some respects, preferable to the sulphate of that metal. By repeated macerations in the decoction of galls, and drying it between each of them, silk may be made to imbibe an increased proportion of their soluble matter, and having done this, PERMANENT COLOURS. 463 it will attract an increased proportion of the oxide of iron, and thus acquire nearly a fourth part more in weight than it originally possessed, be- fore its gummy covering had been separated by the boiling with soap. But the colour produced by this excess or superfluity of the black dye, is not commonly so perfect, or so permanently fixed, as it is when no such excess has been em- ployed. In addition to other means, and in order to improve their effects, silk dyersoften providethem- selves with what is called a black vat, (or tonne au noir, by the French) composed of ingredients, differing considerably in different places ; of which, however, the principal are vinegar, sour beer or cider, and oatmeal in water, with alder- bark, sumach, oak- bark, and sometimes galls ; to which old iron hoops, or other thin pieces or minute divisions of that metal are added, and left to undergo a gradual dissolution, by the joint ac- tion of the acetous acid, and of that contained in the acerb vegetable matters just mentioned, or others possessing similar properties. The longer these mixtures have been made, the better they are found to answer the purpose for which they are intended. At Genoa (which has long been celebrated for its black dye) and other places on the continent, such vats have been made to sub- sist for ages, being replenished, from time to time, by additions of the several ingredients, (some of ■ «885 m?} 4Gi PHILOSOPHY OF them, probably, useless). »as fast as those formerly supplied may appear to have been exhausted. The black dyed at Genoa upon velvet, and also upon a thinner sort of woven silk, to which I applied strong muriatic acid, appeared to have been produced with some, though not a large propor- tion of, logwood, and not to have received any blue ground from indigo or woad ; and, indeed, this ground, though some persons have recom- mended it, is, I believe, now rarely given any where in the dyeing of silk black. The Chinese are said to improve their black dye upon silk, by passing it, when dyed, through a bath containing at the rate of one pound of starch, with half as much of the oil of linseed, or of rape, or hemp-seed, for every five or six quarts of water. M. Berthollet (torn, i. p. 1(3.) has described a process, communicated to the Academy of Lyons, in 1776, for dyeing silk, by M. d y Angles ; but, on account of its length, I beg leave to refer my readers to that description, should they de- sire to know more of it. Of the Application of the Black Dye gerterally, to Cotton or Linen, either woven or spun. The late Dr. Lewis, after mentioning the diffi- culty which attends the application of the black dye to silk, adds, that " the dyer of linen and cotton thread, however he prolongs the operation, or repeats the dippings, is unable to communicate PERMANENT COLOURS. iGS to the thread a blackness that shall endure wear- ing." That there was some foundation for this observation at the time when it was made by Dr. Lewis, I am disposed to admit ; though it must have resulted chiefly from the improper methods employed to communicate the black colour to these substances ; for certainly the oxide of iron has more affinity, and unites itself more readily and permanently, with the fibres of linen and cot- ton, as is daily observed, in what are called iron- moulds, and in the buff colours produced by it, than it does with the fibres of either wool or silk ; and, indeed, more permanently than any other basis is known to do ; and there being a marked attraction between this oxide and the colouring matter of galls, sumach, &c. the black produced by these means, might well be expected to prove as durable on linen or cotton as on wool ; and probably the only reason (in addition to the improper methods of dyeing) why it has not been thought so, is, that linen and cotton are subjected to occasional washings with soap, which is rarely applied to wool and silk when dyed black. Hitherto the dyers of cotton and linen have been accus- tomed, like those of wool and silk, to apply the vegetable part of the black dye first, and the solution or iron afterwards ; thereby inverting the order observed in regard to other adjective colours, but with much less reason for doing so than the dyers of wool and silk have ; at least, if the vol. ii, h h 46G PHILOSOPHY OF results of my experiments are not very falla- cious. It is notorious that the calico printers, wl.en they wish to produce any adjective colour,by the lid of iron or its oxide, as a basis, invariably begin by applying the basis (commonly the acetate, or the pyrolignite of iron) separately to the calico* superadding the vegetable colouring matter after- wards ; excepting only in those cases where a !ess permanent prosubstantive black or other colour is applied, for which the basis or mordant is pre- viously mixed and combined with the vegetable colouring matter. And it is well known that the black and other colours given by calico printers, from sumach, madder, weld, quercitron bark, &c. upon an iron basis, applied first and separably ', are much more lasting than the same colours produced in a different manner by the ordinary dyers. And it has not, I believe, been found that the colours produced by calico printers, upon an iron basis, separately and previously applied, had injured the texture, or shortened the wearing of the calico, any more than colours given by the aluminous basis, at least when the acetate or pyro- lignite of iron had been duly prepared and applied ; though it must be admitted that iron, in a certain state of oxidation, if accumulated in or upon the fibres of linen or cotton, will render them brittle by impairing their flexibility. Of this fact I need only give the following instance or illustration,: Having more than twenty years ago prepared PERMANENT COLOURS. 46? two solutions, one of the green sulphate, and the other of the nitrate of iron, and having thickened them by suitable additions of powdered gum arable, I marked an equal number of shirts and pocket handkerchiefs with each ; and leaving them to undergo the usual course of washing and wear- ing, I observed, from time to time, the compara- tive effects of these different preparations of iron. The letters which had been marked with the sul- phate, soon became of an even, smooth, pale yellow colour, which did not sensibly diminish, either in quantity or appearance, by any subse- quent washing, nor did the parts or fibres of the linen to which this sulphate was applied appear less flexible, or ultimately prove to be in the slightest degree less durable than the other parts generally. But the effect of the nitrate of iron was very different, as the letters produced by it were of a brownish orange colour, with a rough unequal appearance, and the fibres of the linen, impregnated with the oxide, were so manifestly rigid, that I was not much surprized at finding holes produced, instead of the marks or letters, after a few washings. It appeared in this case, that the nitric acid had not only produced a much higher degree of oxidation, in the iron dissolved by it, but had combined with a larger proportion of the metal j so that, in addition to the greater oxidation, there was an accumulation of the oxide, where it had been applied to form Hh2 468 PHILOSOPHY OF the letters or marks ; and the corroding influer.ce of this accumulation was, doubtless, augmented by farther and continued absorptions of oxygene from the atmosphere. From the results of this and other experiment, I have long been convinced, that a nitrate of iron cannot be directly applied to the fibres-of linen or cotton, without producing injurious effects, unless it be much diluted, and very mi- nutely divided ; or unless it be mixed with a carbonate of potash-, or some other matter suited to obviate the rigidity and corrosive influence which it would otherwise occasion. It has, in- deed, long been a practice among calico printers, to dissolve iron by aquafortis, and afterwards mix the solution with a decoction of galls, to produce a prosubstantive black for topical application. By which mixture, the nitrate of iron is deprived of a part of its oxygene, and the oxide so much divided as to hinder, in a great degree at least, the accumu- lation and consequent rigidity before mentioned. Though there has often been some reason to think, that even this application was not innocent, in re- srard to the fibres of the calico blackened by it. There is, however, no cause to fear this sort of injury from a direct application of the acetate, or the pyrolignite of iron, in the usual ways, as a basis for the colouring matter of galls, sumach, &c. ; and I am confident, from the results of many experiments, that being so applied, (in the PERMANENT COLOURS. 469 manner, and with the precautions mentioned be- tween pages 312 and 319 of my first volume) there can be no difficulty, afterwards, in pro- ducing 2. full and permanent black, by dyeing the linen orcotton,whichhas received this basis, with a suitable portion of galls, with or without an addition of sumach, and even without the co-operation of a blue ground, (from indigo) which is com- monly thought necessary, at least for the finer and more costly cotton, or linen goods, intend- ed to> be made black : when linen and cotton have been so dyed,the colours may be more strongly fix- edly passing them through a weak solution of blue. It may be proper, after having suggested what I consider as a decided improvement in the mode of applying the black dye to linen Or cotton, that I should notice the methods most generally practised and approved for imparting that colour to these substances. M. le Pileur d'Apligny (in his " Art de la Teinture des fils et etoffes de Coton,") describes the process most esteemed and practised for this purpose at Rouen ; and by his description it ap- pears that cotton yarn, and linen thread, are first dyed blue with indigo, and afterwards galled ; employing a quarter of a pound of gall- nuts for each pound of yarn or thread ; they are afterwards macerated, and worked by hands, three several times, in the liquor of the black vat, dry- ing them between each of these macerations ; and being finally well rinced, they are dyed with si *70 PHILOSOPHY OF quantity of galls and alder bark, sufficient to saturate the iron applied by the liquor of tlie £>lack vat. To soften the black so produced, the thread and yarn are commonly passed through a remnant of weld liquor, and afterwards through a bath of warm water with whichlinseed oil has been jnixed and well stirred ; employing for this pur- pose at the rate of one ounce of oil for each pound of the dyed thread or yarn. This em- ployment of linseed oil, gives a soft glossy ap- pearance to the black dyed upon linen and cotton, and it also renders the colour more intense and durable ; and it should always be so em- ployed, when linens and cottons have been dyed black, in the manner which I have just re- commended, i. e. that of first applying the acetate or pyrolignite of iron, and afterwards the colour- ing matter of galls and sumach. But care must be taken not to withdraw the linen or cotton yarn from the mixture of oil with water, until, by suitable management, the oil has been equally dispersed and applied to the dyed substance. For cotton-vclvcts, indeed, and piece goods, it will be advisable first to apply the oil generally, over the surface, by a brush, and afterwards favour the spreading and absorption of it equally by passing them through warm water. Goods which have been dyed with a pyrolignite of iron, must be afterwards well aired, lest they should retain the unpleasant smell which accompanies that acid. PERMANENT COLOURS. 471 M. Vitalis (see Manuel du Teinturier sur fil et sur Coton file, p. 127,) strongly recommends the following process for dyeing black upon thread and cotton yarn, viz. Let them be first galled, employing from two to three ounces of galls to each pound of thread or yarn, and then macerated in a warm pyrolignite of iron, marking from five to six degrees upon the areometre of Beaume, equal to about 1*040 of the common standard. After this impregnation, they are returned again to the decoction of galls, and afterwards to the pyrolignite of iron, replenishing each of them, from time to time, until the proper colour shall have been produced ; which, in his estimation, will not require more than five ounces of galls, and sixteen ounces of the pyro- lignite of iron, (of the strength just mentioned) for each pound of thread or yarn: after which the latter are to be rinced, dried, and impregnated with lin- seed or olive oil, in the manner lately described. The most common method of dyeing cotton black, at Manchester, has, at least until very late- ly, been that of first making it imbibe the colour- ing matter of galls, or sumach, and then satura- ting this colouring matter with the liquor of the black vat ; then passing it through a decoction of logwood with vcrdigrise ; and repeating these impregnations until the desired colour was pro- duced, but always drying the cotton between each. Now, however, the pyrolignite of iron is frequently substituted for the liquor of the black • "'''• .-'.' 3».^. PHILOSOPHY OF vat, but not, as I believe, applied previously to the vegetable colouring matter. M. Hermbstaedt, of Berlin, has lately recom- mended (in the Biblioth. Phys. GEconomique, in. xiv.No.2,) a method of dyeing black upon cotton, by applying to the latter a mordant consisting of the oxides of iron and copper, precipitated from so- lutions of the sulphatesof those metals,and heated so as to make them absorb a maximum of oxyger.e; after which, they are to be dissolved in the pyrolig- neous acid ; the cotton being impregnated with this mordant, is to be dyed with galls, sumach, log- wood, &c. But having already stated that the oxide of copper can be of no use in producing a black colour, otherwise than by combining with the co- louring matter of logwood, and that the blue, which it forms by that combination, is more fugitive thin the black which logwood forms with the oxide of iron, when no copper is employed at the same tin.e, it can hardly be necessary for me to observe, that M. Hermbstaedt's mordant is faulty, in as much of it as relates to the oxide of copper, of which the seeming good effect cannot be lasting. Of the application of the Black Dye, topicalhj ar.d prombstantivety to Calico, §c. Thave already, in several parts of this work, and particularly at p. £52 and 3 of my first volume, mentioned the method employed in the East Indies to produce black figures, or stains, upon calico, which has imbibed the colour'n master of PERMANENT COLOURS. 473 the terminalia chebula, partially or topically, by applying to it a solution of iron by the acetous acid ; and I have in other parts, and especially between pages 375 and 3?9> of the same volume, described the opposite method employed by Eu- ropean calico printers, of communicating similar figures or stains to calico, by first printing or applying the solution of iron (by the acetous or pyroligneous acid) to the calico, and afterwards superadding the vegetable colouring matter, (com- monly from madder or sumach,) by a dyeing pro- cess. It,therefore, only remains for me to offer some observations respecting the application which it is often highly convenient to make in calico printing, of the matters affording writing ink prosubstantively, or in a state of combination, instead of either of the other methods of apply- ing them separately. Forty years ago, some calico printers, . as I was then informed, knew that the colouring matter of galls, produced a more permanent prosuhstan- tive, or, as they termed it, chemical black, when combined with iron dissolved by aquafortis, than it did by any other preparation of that metal with which they were acquainted. No one, how- ever, then appeared to suspect the cause of this in- creased permanency, though it will now be readily understood to have resulted from the greater degree of oxygenation which the iron had ac- quired from this acid ; but, unfortunately, it also - ! ,-■■ &.. , j^v^rKV- vSSSaSsiCTEsi^^^^i'* <74 PHILOSOPHY OF acquired properties which were sometimes found to have injured the texture of the calico staned by it 5 especially when the nitrate of iron had been employed in such proportions as were suited in other respects to produce the best and most durable colour; and when the composition, after its application, was, as is usual, dried in places artificially heated. The use, however, of this composition, has subsisted until the present time; and the following is, I believe, the most approved method of preparing it, viz. Take single aquafortis, or nitric acid of the specific gravity of about 1*260, and let it dissolve iron until saturated therewith ; and having a: the same time made a decoction of the best galls, of which each gallon should contain the colouring matter of two pounds of the nuts, mix these to- gether, in the proportion of eight ounces of the solution, or nitrate of iron, to each gallon of the decoction, and let the mixture be properly thick- ened, according to the method in which it is in- tended to be employed, or applied ; if by the pencil, with gum tragacanth. The mixture, if made with ten, or even twelve ounces of the nitrate of iron, instead of eight, will work more pleasantly, by affording neater and better defined impressions, and with some improvement of the colours; but there would then be danger of its hurting or weakening the fibres of the calico. The black produced by the mixture just described, is sufE- PERMANENT COLOURS. W Iciently listing for all the ordinary uses of printed calicoes, and unobjectionable in regard to its ap- pearance ; and were it always innocent in regard to the texture of the doth, there would be no great need to seek for any other. I ought to ob- serve, that instead of water, some persons think it better to employ vinegar to extract the colour- ing matter of galls. A composition for this purpose, is not unfre- quently made, by adding to each gallon of the decoction of galls, twelve ounces of the sulphate of iron, (instead of the nitrate of that metal,) and boiling the mixture, for an hour, or an hour and one half, by which it will gain a considerable portion of oxygene, and with it a deeper, and more permanent black colour. This composition has been, and I think justly, deemed harmless, in re- gard to the fibres of the cotton ; though when thickened with flower, for printing by the block, it does not unite therewith permanently ; but in a day or two separates, or parts, in the language of the printers, so as not to be capable of adhe- ring equally and properly to the block. By cal- cining the sulphate of iron, previous to its mix- ture with the decoction of galls, the subsequent boiling, except for a few minutes, would be ren- dered unnecessary, and the iron would become even more oxygenated than by the boiling. Some persons employ a portion of the colouring matter of logwood, conjointly with that of the galls, which 4 476 PHILOSOPHY OF renders the black more intense at first ; but this effect, or addition of colour, will not be so per- manent, as the black resulting from the combina- tion of iron with the soluble part of galls. Some years ago, I purchased of a calico printer, possessing great knowledge of the principles and practice of his art, the secret of a compcsition which he had employed wifh success, as a prosub- stantive black, and which, as far as I can judge from experiments upon a small scale, deserved the high commendations which he bestowed upon it ; and though I have never obtained the smallest pecuniary advantage from this purchase, in any way, I will here give the full benefit of it to the public. The following was his recipe, with some abreviations of language, viz. Take two pounds of the best mixed galls in powder, and boil them in one gallon of vinegar, until their soluble part is extracted, or dissolved j then strain off the clear decoction, and add to the residuum of the galls as much water as v/ill be equal to the vinegar evaporated in boiling; stir them a little, and after allowing the powdered galls time to subside, strain off the clear liquor, and mix it with the former decoction, adding to the mixture six ounces of sulphate of iron ; and this being dissolved, put to it six ounces more of sulphate of iron, after it has been previously mixed with, and dissolved by half of its weight of single aqua- fortis ; let this be stirred, and equally dispersed through the mixture, which is to be thickened PERMANENT COLOURS. \ 477 by dissolving therein a sufficient quantity of gum tragacanth, (of which a very small proportion will suffice.) Calico after being printed or pen- cilled with this mixture, should, when the latter is sufficiently dried, be washed in lime water, to remove the gum and superfluous colour, and then either streamed or well rinced in clear water. This composition has not been found to wea- ken, or injure, the texture of calico printed or pencilled with it, and the colour is thought unob- jectionable in regard to its blackness and dura- bility. I ought here to mention, that when sulphate of iron is mixed with aquafortis, the latter under- goes a decomposition ; the oxygene of the nitric acid combining with the iron, and raising it to a much higher degree of oxidation ; and that the result of these operations is the production of a fluid which has the consistence, and smooth appearance of oil, and which, (though the name may not be quite unexceptionable,) I will call a nitro-sulphate of iron. I have, however, been induced to believe, from several trials, that a better prosubstantive black than either of those here mentioned, or indeed than any other within my knowledge, may be formed, by taking a decoction, containing in each gallon the soluble matter of two pounds of the best galls in sorts, and, when cold, adding to it for each gallon twelve ounces of sulphate of iron, which had been previously mixed with half PHILOSOPHY OF its weight of single aquafortis, (of which one ' { wine pint should weigh about twenty ounces) j and, by the decomposition just described, con- verted to the nitro sulphate of iron just men- tioned. By thus employing twelve ounces of j sulphate of iron, oxygenated by nitric acid, instead of six ounces of the latter, with six ounces of the green sulphate in its ordinary state, an improvement in the colour seems, by my experi- ments, to have been invariably produced, and without any corroding or hurtful action upon the fibres of the cotton. It having appeared to me, some years ago, to be highly expedient that the comparative degrees of stability and permanency, of the black colours, which galls, myrobalans, sumach, and logwood, were capable of affording with iron, should be ascertained, and knowing that each of them, with certain proportions of this metal, was capable of affording a blacker and more lasting colour than with any other less suitable proportion, I projected and executed the following experiments, as being eminentlv adaDted to manifest the truths which 4 J- appeared so desirable. I prepared half a pint of a decoction of galls, which was made to contain the soluble matter of two ounces of the powdered nuts in sorts, and having ascertained the specific gravity of this decoction, I prepared a like quantity, and of the like specific gravity, of the decoctions of su- PERMANENT COLOURS. 47* mach, logwood, the fruit of the terminalia che- bula of Retz, (or yellow myrobalans of the shops) and also of the ash-coloured pear-shaped fruit, of another species of myrobalans, then recently im- ported from India, and which I take to be the tcr- minalia bclerica of Roxburgh.* At the same time I prepared what I thought a sufficient quan- tity of the nitro-sulphate of iron, recently de- scribed^ by mixing six ounces of the green sul- phate, with three ounces of aquafortis ; and hav- ing properly thickened the several decoctions with equal portions of gum tragacanth, I, with a sui- table glass measure, put into each of them two- drachms of the nitro-sulphate of iron, and having mixed it equally, I applied a little of the five several decoctions,or mixtures, to one end of a long strip of white calico, taking five strips for this purpose, and appropriating one of them exclusively to each of the several decoctions or mixtures. Each of these Jirst applications was followed by twenty- four others, all made in succession, but only after one scruple of the nitro-sulphate of iron had been added to each of the several decoctions, and well mixed with it previously to any new application. * They could not have been the fruit of the phyllanthus em- blica, as some persons then supposed, because the latter is de- scribed by Louriero as being three celled and two seeded, whilst the stoney shell of the fruit under consideration, had but one cavity or cell, with a single kernel. 4S0 PHILOSOPHY OF In this way, thirty scruples of the nitro-subhate of iron had been added at twenty-five different times, to each of the five mixtures, when the last application of each to the calico was made, and each strip, when dried, and properly clemsed with lime water, &c. exhibited the colour or affect of twenty-five several applications, all with diffe- rent and increasing proportions of the nitn-sul- phate of iron. And as the first application to each of the five strips contained only about one- fourth of that portion of iron which I supposed requisite to produce the best colour, so the last contained double that portion, by the sabse- quent additions, joined to the continued abstrac- tions of vegetable colouring matter, which [hese several applications required ; and I was, therefore, certain, that though the first application would contain too little iron, and the last too much, one at least of the intermediate ones, in each of the five strips, would contain the exact proportion required to produce the best and most durable black, which that particular vegetable was capable of producing with the nitro -sulphate of iron ; (and probably the best which it would produce with any other preparation of that metal,) and that by comparing together the best of the seve- ral strips, I should be able to ascertain the desired truths. These several strips having been washed with soap and water, were fastened, by small tacks, each to a separate board, so that the same surface. PERMANENT COLOURS. 481 fully extended, was constantly exposed to the sun and air, on the south side of my garden-waft, against which the several boards were placed du- ring three summer months, in such manner that the portion of sun-shine upon each, was as equal as I could make it. Recollecting when this experiment was devised that it might also be highly useful to ascertain whether the sulphate of copper, so frequently re- commended and employed for dyeing black with logwood, was capable of producing with that wood, a colour as lasting as the black which it produces with iron, I took an equal quantity of the same decoction of logwood, with which the nitro-sulphate of iron was mixed in the preceding experiment, and having thickened it also with gum tragacanth, I mixed with it two drachms of powdered sulphate of copper, and applied some of the mixture to a sivth strip of cotton, to which were added twenty-four other applications, each containing an addition of one scrupfe of powdered sulphate of copper more than the preceding, and this being dried, cleansed, and washed exactly like the other five strips, was in like manner ex- posed by the side of one of them, at and during the very same time. The colours of the several strips under consi- deration, beine; examined after having: Deen thus exposed, during three summer months, those near the middle of each strip were in general, found to VOL, II, I i - 482 PHILOSOPHY OF be comparatively the most perfect, and to have suf- fered the least by this exposure. There were in each strip three or four applications adjoining each other, which, though made with some difference in the proportions of metal, had produced effects equally good ; and this fact seemed to prove, that somesmall latitudeor variation in that respect might be admitted, without harm. Of the mixtures with iron,a considerable part of those in which that metal had been used too sparingly, were found to hive produced colours which, though only brownish purples, or purplish blacks, had not greatly faded j whilst those in which the iron was in the grearest excess, were become rusty browns, but little better than iron moulds. Generally, however, the colours upon each strip were deficient either in blackness or durability, according to the degrees in which they severally receded, on each side,//w« the more central and perfect blacks. Those with some excess of iron had at first appeared more black than those with an excess of vegetable mat- ter ; but the latter proved more durable. Vl r hen I came to compare with each other, the best colours in each of the first five strips, I found those from galls, and from the fruit of the terminalia chebula, or yellow myrobolans, to be considerably better than any of the others, and so equally good, that I knew not which to prefer. They were, indeed, but slightly injured by the ex- posure which they had undergone. Next to PERMANENT COLOURS 483 these were the best of the colours produced from sumach, and nextafter these, those from vvhatl sup- pose to have been the fruit of the terminalia be- lerica ; the difference, however, was great between the latter and the colours from the yellow myro- balans ; which last, therefore, and the galls pro- duced upon the same tree, ought, as I think, to be exclusively imported. The least permanent of the colours produced with iron, were those afforded by the logwood ; but even these were considerably more durable than the colours which the same wood had afforded with the sulphate of copper ; which, by several comparative trials, I have found to be more lasting upon cot- ton than upon wool : and it is in consequence of the results of these several experiments, that I have endeavoured to discourage the use of sulphate of copper, or verdigris with logwood, in the black dye ; and especially when it is to be applied to woollen cloth. From the experiments, of which I have just given an account, as well as from many others, I infer that twelve ounces of the sulphate of iron, converted into a nitro-sulphate, as before described, contain such a portion of iron as will prove most efficacious and suitable for the colouring matter of from two pounds and one half to three pounds of the best Aleppo galls in sorts, when they are employed to compose a prosubstantive black colour. lis 484 PHILOSOPHY OF In addition to this account of the uses and ef- fects of galls, sumach, myrobolans, and logwood, it may be proper that I should notice some few of the other vegetable matters which are capable of being employed with iron for similar purposes. One of these was mentioned by the late John Rheinhold Forster, in a communication which he made to the Royal Society, in 1772, and which was published in the sixty- second volume of their Transactions ; of which the following is an extract, viz. " The inhabitants of Mexico have but lately learnt of the inhabitants of California, the art of dyeing the deepest and most lasting black that ever was yet known. They call the plant they employ for that purpose cascalote; it is arboreous, with small leaves and yellow flowers ; its growth is slower than that of oak : it is the least corrosive of all the known substances em- ployed in dyeing, and strikes the deepest black ; so that for instance, it penetrates a hat, to such a degree, that the very rags of it are thoroughly black. The leaves of this cascalote are similar to those of the husioke, another plant likewise used for dyeing black ; but of an inferior quality. The latitude of California lets us hope, that the country near the Mississipi, or one of the Floridas contains this cascalote, the acquisition of which would be of infinite use in our manufactures." This account is defective by not affording any PERMANENT COLOURS. 48 & intimation respecting the basis or mordant with which (if there be any) this vegetable was em- ployed to produce these effects, or respecting the name under which it may have been kn@\vn to Botanists, or the genus to which it might be re- ferred. I conclude, however, from many circum- stances, that it belongs to the comprehensive genus of mimosa (which contains many species capable of dyeing black with iron,) and in fact that it must be the mimosa juliflora lately mentioned, at p. 448, as affording an excellent ink : it seems not to have been indigenous at Jamaica ; but now grows there in considerable plenty, whence it might perhaps be advantageously imported to this country. Michaux (p. 243) mentions the andromeda arborea, or sorrel tree, as bearing beautiful pani- cles of white flowers, with acid leaves, which are preferred by the inhabitants of the Tenesec country to sumach for dyeing black. Loureiro (torn. i. p. 1 S6) mentions the leaves of the cras- sula pinnata as being employed in Cochinchina for the same purpose; " ad tingendas telas colore nigro usurpantur :" and at p. 573, he informs us, that a similar use is there made of the leaves of the juglans catappa. Having lately mentioned the bark of the acer- rubrum, or scarlet flowering maple of North America, as affording with iron, the purest, most ■perfect, and durable, black, 1 need only express OHmBBS *-^^^Tw^-^^-Tjf. f^^T^f^^-^^^'"**^ iJ^TO^CWTTC 486 PHILOSOPHY OF, &c. my hope that it may speedily be brought i.ito general use here for dyeing that colour. The bark, leaves, and fruit of the anacardhm occidental, or cashew-nut tree, (casuvium of the French Botanists) afford copiously a colourng matter, which with iron produces ink and dyes black. The laurus borbonia, diospyros virgni- ana, morinda royoc, and many other vegetatles, might be mentioned as producing similar effects ; but I think it proper here to finish this chapter, and with it my present Work. Whether I stall hereafter make any addition to it, will depend on the prolongation of a life, of which the sixty- ninth year is now passing away ; and upon ot.ier events, which, notwithstanding my inclination for this subject, may, in a great degree, withdraw my attention from it. THE IND. GENERAL INDEX. N. B. A line between the numbers of two pages which are not con- secutive, indicates that the subject is continued from the former to the latter, through the intermediate pages. ACER RUBRUM, affords with iron a pure and perfect black for ink and for dyeing, ii. 363, 364, 485. Adjective colouring matters, what they are, i. 341 & seq. 1- Colours, causes which affect their durability, i. 345, 346. Alder bark, its use in dyeing, ii. 368. Aloes, a lasting purple dyed therewith, i. 289, 291. Alkanet, ii. 313. Alterants in dyeing, i. 344. Alum, its history and extensive utility, xxi— xxxvi. mines at Tolfa, discovery and importance of, xxxii— XXXV. • ■-, the 'first production of in England, xxxvi. — — — , not decomposed by wool when dissolved and boiled therewith, i. 385 — 39O. Aluminous mordant, how employed for East Indian calico printing! i. 354, 355. Alumine, acetate of, how applied in European calico printing, i. 362 n.363,n. ii. 17Q, 178—184. ■ , how its acid is afterwards separated, i. 364, n. -. 1 ■■ , advantages of this composition, i. 365, 366. its history, i. 367—369. ■■■■' ■" ■-■ ■ - was not an East Indinn invention, i. 3/0, 371. 4S8 INDEX. Aiumine, a more copious precipitation of it necessary for dyeing linen and cotton than wool, ii. 148, 14g. The useof gall nuts, myrob:ilans, sumach, &c. in promoting this precipitation, ii. 157 — 159- Why its application primarily, and without colouring matter, is most ad- vantageous, ii. l6l and n. Aiumine, its effects when combined with different acids and alkalies, ii. 159— -l6l. Amyris toxifera, or poisonous ash, its black juice, i. 310. Anchusa Tinctoria, ii. 313. Andeman Islands, their dyeing wood, ii. 331. Anderson, Dr. James, his mistake respecting cochineal, i. 441 , 442. Annotla, its history and use, i. 281—283. Areca nuts, their colouring matter and use in fixing colours, ii. 369. Astringency in vegetables, generally, but erroneously, supposed to indicate in them the property of rendering so- lutions of iron black, ii. 39O, n. 39 1. 406—408. Atramentum sutorium, ii. 423. Barbary, seeds from, for dyeing red, experiments with them, i. 285, 286. Barberry shrub, i. 273 . Barasat verte, or green indigo, experiments with, and conclu- sions respecting it, i. 266 — 275. Barwood, its uses in dyeing, ii. 335. Bases to attract and fix adjective colouring matters, i. 342 — 344. "Why they ought to be applied before the colouring matters, i. 344, 345. An illustration of their effects, i. • 346 and seq. Beaujoqr, M. his account of the Grecian method of dyeing Turkey red, ii. 261, n. Eeckman, his opinion concerning the alum of the Greeks and Romans, examined, xxii — xxviii. < ■ scarlet from Kermes, i. 393, 394 Belcher, his account of the effects of madder upon the bones of animals, ii. 233, n. INDEX. 189 Bergman improves the theory of dyeing, liv. errs in ascribing the blue colour of indigo to iron, i. 196. ■ , his method of dyeing black, ii. 459. Berkenhout, Dr. his method of applying the scarlet dye to cotton, i. 536 — 538, and n. Berries, French or Turkey, ii. 100' — 108. Berthollet, his elements of dyeing applauded, lv, lvi. ■ adopts the author';; objections against the Newto- nian doctrine of colours, i. 33, n. supposes the sun's rays to injure colours only by promoting a partial combustion of them, i. 55 — 58- ■ Objections to this doctrine, i. 59 — 65. , his answers to the author's objections, with the author's remarks, i. 65— 71. ■ errs in supposing that the first indigo employed iti Europe was brought by the Dutch round the Cape of Good Hope, i. 245 — 248. ■, his commendation of the quercitron bark, ii. 158. ■ errs in supposing that ink is black only because the iron contained in it is in the state of a black oxide, and the galls in that of carbon, and why, ii. 413 — 423. Birch, Mr. invents the barasat verte, &c. i. 260", 273 — 2/5. Bischoff errs in supposing indigo to have been unknown to the Greeks and Romans, i. 211 — 243. , his account of the scarlet from Kermes, i. 394. Black dye, its theory, and the means by which it may be pro- duced, ii. ;j87& seq. may be dyed upon wool by an accumulation of yellow, red, and blue, or of blue only, i. 233. ii. 388, 389, "• 1 ' dye, its similitude to ink in composition and theory, ii. 389 & seq. — — worn among the Greeks and Romans only as mourning, and in sacrificing to the infernal gods, ii. 449. — — , Act of Parliament respecting the dyeing of it, ii.451. »■...,.. dye, its application to wool and woollen cloth, ii. 44g — 460. BHH 9 i 9 490 INDEX. Black dye, causes of its supposed injury to stuffs dyed with it, ii. 452, n. • " ' , its application to hats, ii. 457. , its application to silk, ii. 461—464. — — — — , its application generally to linen and cotton, ii. 465, 466, 468, 469. , how dyed upon linen and cotton at Rouen, ii. 469,470. ■ ■ — —and at Manchester, ii. 471,472. — — , method of dyeing it recommended by M. Vitalis, i:. 47 1 . and by Hermbstaedt, ii. 472. — — , prosubstantive for calico printing, different, and the best rfteans of producing it, ii. 472 — 478, and 483. Black, an important experiment to ascerta n the comparative stability of this colour when produced by the different vege- tables employed for that purpose, and its results, ii. 478—483. Black, sundry vegetables useful in dyeing this colour, and in making ink, ii. 484—486. Black Walnut of America, its use in dyeing, ii. 367. Blood, arterial, its fine vermilion colour produced by oxygene, i. 62. Blue, derivation of the word, i. ]27, n. — — , several vegetables for dyeing that colour adjectively, ii. 356,357. , the dyeing of it upon wool from logwood justly prohi- bited, ii. 454—456. Blue, Prussian, see Prussian blue. Blue, substantive, see indigo and woad. Bon, M. his discovery of a silk from spiders' eggs, i, 101, 102, Bonnet, M. quoted, i. 44. Brasil wood, its history, ii. 316 — 323. Its name given to, and not derived from, the country now called Bra- zil, ii. 318 — 321. Solubility of its colouring matter, ii. 323. How impro\fcd, ibid. Con- tains no tannin, ii. 324. Made yellow by acids, purple by alkalis, and colourless by sulphuretted INDEX. 491 Hydiogenegas, ii. 324. How acted upon by solu- tions of tin and of aluraine, ii. 324, 325. Its colour rendered more permanent by galls and arsenic, ii. 325, 326. How applied to dye wool and woollen cloth, ii. 326—328, and to dye cotton, ibid. Effects of different bases and mordants upon its colouring matter, ii. 326 — 329. Its colour not preserved by being covered with oils, ii. 327- Brasilletto, or Jamaica red wood, ii. 333. ■ , or Bahama red wood, ii. 333, 334. Broadcloth, effects of the scarlet dye upon it., i. 524, 525. Buchanan, Dr. his account of the asclepias tingens for dyeing green, i. 2/5, 276. Buccinum lapillus, the author's experiments therewith, to pro- duce and explain the production of the Tyrian purple, t. 146 — 157. ■ ■■■•■ ■ » ■ ■-, its colouring matter remarkably demon- strates the influence of solar light, in pro- ducing colours by separating oxygene, i. 80. Buffalo's milk, how employed for East Indian calico printing, i. 354. Butternut tree, the use of its bark in dyeing, ii. 365, 366. Cactus cochiniiifer, &c. i. 412. Calico printing, illustrates the uses and effects of the bases of adjective colours, i. 346. ... - ' ■ , Pliny's account of it as practised in Egypt, i. 347- The art probably invented by the Hindoos, i. 348, 349- How practiced by them, i. 349 — 35 9- Theory of its different operations, i. 356—358. The art greatly sim- plified in Europe, i. 359. How practised ia Europe, i. 359—388. ii. 174 — 184. Camocladia integrifolia, its juice gives a black stain, i. 31 1. " ' . > the juices of both produce permanent black stains, i. 311. , *»? -192 INDEX. Camwood, its history and uses in dyeing, ii. 334. Caneparius, his mention of indigo, i. 244 — 246, and of cschi- neal, i. 411.447. ■ ■ - " -, his account of writing inks, ii. 428—433, and of black for staining linen, ii. 432. — — , his method of restoring the black of decayed writings, ii. 433. Chaptal M. has contributed to improve the art of dyeing, lvi. his account of the preparation of wool for dyeing, i. 8/. n. His error in supposing the blue of indigo to depend on carbon, i. 197. His theory of the Turkey red dye, ii. 264 — 270. His observations on writing ink, ii. 435 — 439. His account of an ink which resists oxymuriatic acid, ii. 444, 445. Charcoal, its existence as such naturally, first denied by the author, with facts in support of that denial, i. 56 and n. Che, or chay root, (Oldenlandia umbellata) its history, &c. ii. 282, 283. How employed for Indian calico printing, i. 356, 357> and for dyeing the Malabar red, ii. 284—297, other experi- ments therewith, ii. 298 — 302. Future importations discouraged, ii. 302, 303. Cheston, Dr. procures the Buccinum lapillus for the author, i. 146. Chevreul, M. his error in regard to the extract of logwood, ii. 344. Chinese, borrowed the art of dyeing from India and Persia, xxix« Chlorine, reasons for not adopting this name. Preface. Clarkson, Mr. his account of the African blue dye, i. 225, and of an African yellow wood, i. 278. Also of an African red dyeing wood, ii. 335, 336. Cobalt, interesting changes of colour, of which the nitrate of it is susceptible, i. 335. Lasting pink and rose colours given by it to calico, ibid. Remarkable changes of colour, produced by heat upon the muriate of cobalt, i. 335 and n. INDEX. 4 n. ]>yer' 3 broom, (genista tinctoria), ii. 108. Dyeing of madder and other colours upon calico, printed with the acetates of alumine and iron, how performed, i. 378— 3S0. Dyeing or staining woollen cloth topically or partially, how performed, i. 3 SI. Dymock, Mr., his scarlet cloth noticed, i. 91 : Ebony, the green, its use as a yellow dye, ii. 106\ Eclipia erecta, used to blacken human hair/i, 311. *- INDEX, 497 Erica, or heath, different species of, for dyeing yellow, ii. 108. Fabroni, his account of a purple, dyed from the aloe plant, i.289- Fulhame, Mrs , her experiments to revive gold, when dissolved and applied to silk, i. 324. Fulling of cloth, explained by Sir William Petty, i. 87, 88 ; and by Monge, i. 88, 89. Fustic, old, improperly so called, see morus tinctoria. Fustic, young, so called, ii. 100. Galium, the roots of several species of it, dye beautiful red colours, ii. 303—307. Gall Nuts, so called, their history, ii. 372, 3/3. Nature of their colouring matter, and its effects with several metallic bases, ii. 3/3—3/5. Effects resulting from a mixture of iron filings with a decoction of them, ii. 416, n. and 417- Their colouring matter strangely overlooked, ii. 411. Not dis- coloured by white muriate of iron, ii. 414, 415. But with the latter instantly made black by nitric acid, ibid. Their origin, unfavourable to the notion of any considerable difference between their colouring matter and that of the oak, ex- cepting its greater purity and concentration, ii.404. Their colouring matter intimately united to their tanning principle, perhaps identified with it, ii. 410—412. Gallic Acid, an artificial production or modification of the acid which causes the acerbity of many vegeta- bles, ii. 401—405 j it blackens solutions of iron only, by retaining a portion of the colouring matter of galls, ii. 410, 41 1. Applied to silk or cotton, it does not enable them to become black with solutions of iron, ii. 409. Observations upon the effects of Scheele's process for pro- curing it, ii. 41 1, 412. Gardenia acnlcata, or indigo berry, i. 2(52, 263. Vol. II. k k 41)5 INDEX. Gardenia flosida, employed in China lo dye scarlet upon cot- ton, i. 285. genipa, its natural history, i. 253. Curious facts respecting the blue stain produced by the colourless juice of its fruit, i. 254, et seq. Employed by the tribes of Brasil and Guiana to paint their skins, as the glastum or woad was by the Britons, ibid. ; and also to play tricks, i. 257, n. Various experiments with the fruit of this tree, i. 259—262. Geuipa americana, Lin., see gardenia genipa. Gmelin, stains silk of a copper colour by nitrate of mercury, i. 331, n. Gobelins, MM., their method of dyeing black, ii. 388. Gold, a solution of it applied to silk and muslin, deoxidated, and made purple by the sun's rays, i. 322, 323. The pu-ple oxide of gold, or purple of Cassins, results from a simi- lar deoxidation, produced by muriate of tin, i. 321, ~2o. Means employed by Mrs. Fulhame and Count Rum- ford to revive this metal from its oxides or solutions, i. 323, 324. How to gild points of lancets and silk by some of these means, i. 324, 325. Other means by which the author has fixed various beautiful and durable purples on silk, linen, and muslin, from solutions of gold, i. 325— 327. Golden rod, American, its use for dyeing yellow, ii. 108, IO9. Gordon, Dr. Cuthbert, the name of cudbear derived from his christian name, i. 300. i 1 endeavours to promote the use of galium verum in dyeing, ii. 305. Green colours, how dyed, ii. 380, 381. Green indigo, i. 264 — 206 : see also barasat verte. Hatchelt, Mr. his analysis of stick lac mentioned, ii. 21, anc a. Haussman, M., gives a violet colour to silk, from solutions of gold and tin, i. 325. His observations concerting indigo, i. 20c), 211, 213. INDEX. 499 Hawkins, Sir Christopher, errs in supposing that tin was era- ployed to fix theTyrian purple, i. 12S, n. Hellebore, three-leaved, for dyeing yellow, ii. IO9. Hellot, his Art de la Teinture des laines, &c. a good practical treatise, li. , errsgreaily in regard to the theory of dyeing, lii. i , his observations respecting the black dye, ii.452. Hemlock spruce, the use of its bark for dyeing, ii. 364. Henry, Mr., his valuable communication to the Manchester Society, on dyeing, noticed, lv. ■ , erred in supposing that the acetate of alumine was an Indian invention, i. 369—37] . — 1 and in supposing that nitric acid was ne- cessary to dye scarlet, i € 538, 539. Hermbstaedt, his method of dyeing black on cotton, ii. 4/2. Herodotus, his account of cotton, i. 10/, n. Herschell quoted, respecting the composition of the solar rays, i. 53. Heyne, Mr. his communication to the Earl of Buckingham- shire, concerning the Malabar red, with observa- tions thereon, ii. 292 — 298. Higgins, Dr., his mistake respecting the barasat verte, i. 273, 274. Hunter, Mr., his account of the Bengal method of dyeing red frommorinda citrifolia, ii. 309 — 311. Hydrastis canadensis, for dyeing yellow, ii. 111. Indigo, made colourless by means which deprive it of oxygene, i. 62. 1/0. and 2l6. Affords a signal proof and illustra- tion of the dependance of colours upon precise portions of oxygene, i. 80. Is the most extraordinary and useful of all dyeing drugs, i. 165. Various plants producing it, i. 166. 172, 173. Means employed by different na- tions to render the juices of these plants blue, i. 167—— Hig, and n. Indigo, in a dry solid form, first produced by the Hindoos, i. 168. Consists of a peculiar matter or basis, which, K k 2 W*. & H^^^^Bf^WlB?^^ fefflsA-^'^E-'I^'Sr: l.- J t~fojfjljfc'j fl«B**tg"!IMgi?S S^i; 500 INDEX. though without colour, becomes yellow, green, and blue, by increased portions of oxygene, i. 216 ; and when made blue, by being saturated therewith, it is in- soluble, without either a previous separation of oxygene, or a destructive operation, i. 170. and 19s, 199. This basis is formed by secretory organs, peculiar to certain plants, i. 170. Theory of the production of indigo, ibid. Effects of an application to calico, of the unfermen'.ed juice of the indigo plant, i. l/l j and of drying it by ex- posure to the sun, i. 1/1, 172. Different methods of extracting the juices of indigo plants, and obtainng indigo from them, i. 173 — 187- Appearances aid effects of the fermentation of these plants, i. 174 — 177. Means of precipitating indigo, when formed by fermen- tion, and the oxygenation of ifs basis, i. 178, lJQ,n. The fermentation of indigo plants how best conducted, i. 180, n. The precipitation of indigo obstructed by carbonic acid, i. 182. Juice of the indigo plant does not become blue if secluded from oxygene, i. 182 — 184. Advantage of obtaining indigo by scalding, rather than by fermenting the plants, i. 184, 185, n. Their fer- mentation accompanied by an absorption of oxyger.e, i. 185, 186. Notice of samples of indigo, produced ay different ways and means, and sent to the author 3y Dr. Roxburgh, i. 18(5, n. His discovery of new plants affording indigo, i. 188, I89. Indigo obtained frcm plants not belonging to the genus indigoferae, i. I89 — Indigo, observations on its differences in regard to specific gra- vity, colour, &c. 191 — 193 ; and on the means of ascer- taining the comparative values of different sorts, i. 193, 194. Analysis of indigo, i. 194 — 196". Is distinguish- able by emitting when ignited, a beautiful purpli, i. 195. , Different ways and means for rendering it applicable as a dye, or useful in calico printing, i. 199 — 221. ■n INDEX. 501 New means to dissolve it, discovered by the author, i. 2! 5. 217, 218. All the means of dissolving, only bring it back to a state of partial oxygenation, as in the fer- menting vat, i. 224. Indigo, sulphat of, observations respecting it, i, 225, et seq. By accumulation, it dyes an intense black, i. 233. , Means of dissolving it most beneficially for Saxon blue, i. 230—232. , the causes of its variations of colour, i. 236 — 238. , is decomposed, and its colour destroyed, by nitric acid, J. 239. Is not soluble by muriatic, citric, tartaric, phos- phoric, or fluoric acids, i. 240. Produces a fine yellow, if dissolved by a mixture of sulphuric, nitric, and mu- riatic acids, ibid. Is soluble by muriate of tin, though not by muriatic acid, and why, ibid. -, additions to its history, i. 2-17 — 251. Used by the Greeks and Romans only as a paint, i. 243. , great and increasing importations of it from the East Indies, i. 249, 250, n. ' , was probably invented by the Hindoos more thao 2000 years ago, i. 250, 251. Ingenhouze, Dr., quoted, i. 44, 45. Ink, Chinese, whence obtained, ii. 430 — to 432, n. —— from iron and galls for writing, theory of its production, ii. 389, et se q- I (s black colour erroneously considered as inseparably connected with vegetable astringency, ii. 390, and n. The author's communication to the Royal Society on this subject, ii. 391. 397, 398. Ink, instances of vegetables, which, though highly astringent, are incapable of rendering solutions of iron black, ii. 391.11. 3f)2 — 394. And of vegetables not astringent, which produce black ink with iron, ii. 394, n. 395. Ink, the author Jirst produced it by a direct mixture of iron- filings with a decoction of galls, ii. 396, 397. Advantages and defects of ink so produced, ii. 399 — 401. - — , galls do not produce it by bringing the iron into the state 502 INDEX. of a Moc/i oxide, and by being also brought into the state of charcoal, as Berthollett supposes, ii. 412—423. Ink, the blackest is produced by iron highly oxygenated, ii. 414 —417. — — , loses its blackness when deprived of a part of its oxy- gene by sulphuretted hydrogene gas, ii. -421 . And re- gains it by absorbing oxygene, ibid. Ink, for writing, how named by the Greeks and Romans, ii. 423. Composed of lamp-black and a mucilage of gum, ii. 427. Which was gradually laid aside for the ink of the moderns, ii. 428. Various mqans and proportions for composing the latter, suggested *by Caneparius, ii. 42Q, 430, and by the late Dr. Lewis, ii. 434. Also by Chap- tal, with the author's observations and improvements, ii. 434— 442. Ink, from iron and galls, its disposition to become mouldy, ii. 422. How counteracted, ii. 443, 444. How its blackness may be restored to old writings, ii. 433. Ink, composed by Chaptal, to resist the oxymuriatic acid, ii. 444, 445. Ink, an indestructible one without iron or galls, inventec by the author, ii. 44/. Other inks, without iron or galls, noticed, i. 312. ii. 448, 449. Iron, the great affinity of its oxide to cotton, i. 313. And to oxygene, i. 314. , solutions of this metal, employed to dye calico substan- tively, i. 314, 315. How applied for this purpose by Chaptal, i. 315—31/, and n. And how at Manchester, i. 3J7,318. , dissolved by muriatic acid, stains cotton of a yellow- colour, which gradually changes by absorbing oxygene, i.318. Iron, acetate of, how prepared for East Indian calico printing, i. 352, 353, n. The knowledge and use of it borrowed by Europeans, i. 375. How prepared and applied by the latter, i. 3/6, 3/7- How calico printed with it, is cleansed, i. 378. Also, ii. 182— 184. n INDEX. 503 Iron, advantage of applying its oxyde separately, and before the vegetable colouring matters, to linen and cotton, in dyeing them black, ii. 465. 468, 469. Iron, its oxyde much less corrosive when obtained by sulphu- ric, than when obtained by nitric acid, ii. 467, 468. Is most efficacious in the production of ink and in dyeing black when highly oxygenated, ii. 414. 41/. 43Q. 4/3. Iron, pyrolignite of, i. 315, 316.3/7. Isatis tinctoria, (woad plant) different modes of fermenting and obtaining its colour, i. 167. ■ , indigo obtained from it in Fiance, i. 167, l63,n. Juglans Alba, or American Hiccory, its use in dyeing, ii. 21 9, 220. — nigra oblonga. See black walnut. • oblonga Alba. See butternut. Kermes, their history, i. 393, et seq. Were employed by the Phoenicians to dye the fine red, which was afterwards called scarlet, i. 394. How denominated by the Hebrews, Greeks, and Romans, i. 3g4, 395. Pliny's account of them, i- 395 — 397. Were appropriated to dye the imperial robes, i. 396. And produced the scarlet in which Jesus was insulted, i. 397. Sir John Chardin's account of their production and use in Media, i. 398, n. Their name derived from the Persian kerm, signifying a worm, ibid. Origin of the term scarlet, i. 399, 400. Chaptal's account of these insects, i. 403, 404. Their colour extremely durable, i 401.405. Was called Venetian scarlet, after that from cochineal upon a basis from tin had been dis- covered, i. 405. Hellot's account of the process for dyeing Venetian scarlet, ibid. The author's experi- ments with them, i. 406 — 408. Kerr, Mr. his account of lac, ii. 3 — 6. Lac (coccus lacca), its history, ii. 1 — 13. Extracts of the co- louring matter prepared in Bengal, and committed to the author for trial, ii. 14 — 19. Hence the origin of lac lake, ii. 20. Analysis of stick lac, ii. 21, 22. The insects and 504 INDEX. their eggs, nearly as rich in colouring matter as cochineal, ii. 22. The difficulty of obtaining it by reason of the resinous cells in which they are contained, ii. 22 — 25. Their colour- ing matter believed incapable of "affording scarlets equally blight with those of cochineal, ii. 25, 2G. This proved to be an error, by an experiment which the author made at Wandsworth, on six pieces of cloth belonging to the £ast India Company, ii. 3S, 3C). Lac, its colouring matter, found by the author, capable of dye'ng colours nearly resembling those of cochineal, with the advan- tage of being more durable, ii. 16, 17. Ways and means ptoposed by the author, on the ground of experiment, to render this matter a beneficial substitute for cochineal in Great Britain, ii. 50 — 56. Means for obtaining the utmost lustre and beauty in the scarlet dyed from lac, ii. 57 ■ Colours which it affords by different bases and mordants, ii. 57 — 59. Lac lake, first tried by the author in 1789, ii. 14, 15. Its advantages and defects, ii. 20, 21. How commorly prepared, ii. 26 — 2S, and fa. Important benefits of a less objectionable extraction of the colouring matter of lac, ii. 32. Means suggested and employed by the author to produce such extraction, ii. 2/ — 33. Experiments made at the desire of a Committee of Directors of the East India Company, with such extracts, ii. 35 — 42. Causes of their partial failure, ii. 42—48. Lac Lake, its defects in a considerable degree obviated, by very minute mechanical division, ii. 4b, 49. Has been advantageously employed in dyeing the Com- pany's scarlets, since the author's successful experi- ment at Wandsworth, ibid. Lavoisier, his doctrine concerning charcoal, refuted, i. 56, n. Lawsonia in ermis, (Hinna of the Arabs) an account of it, i. 283. The author's experiments with it, i. 284, 285. Lead, acetate of, its importance in calico printing, i. 359. How prepared and applied, i. 360—366. INDEX. 505 Lead, its oxide with lime, blackens hair and wool, i, 337. Le Goux deFlaix, his error concerning chay root, ii. 302. Lemnius, a physician of Zealand, first noticed the red co'our given by madder to the bones of animals, ii. 232, n. Lewis, Dr. certain MSS. supposed to have been his, noticed, i. 211, n. , his observations respecting ink, ii. 434, 435. , and respecting the black dye, ii. 453. 461—464. Lichen, different species of, for dyeing purple, i. 2Q1, et seq. Means of applying ammonia to evolve and raise their colour, i. 296 — 299. Better means suggested, i. 302. Defects of their colour, i. 303. Oxygene, as well as am- monia, necessary to its production, i. 304, 305. Light, solar, its effects in producing or changing the colours of animal, vegetable, and mineral substances, i. 38— 43. 45, 46. 48, 4Q. 134, 135. 139. 14;, 148. 322, 323. :— — — , Effects of the differently coloured rays upon mu- riate of silver, i. 40 — 53. — — 3 upon the pur- ple of the Buccinum lapillus, i. 154, 155. Linen, resembles cotton in its affinities to different colouring matters, and its preparations for dyeing, i. 110. •— — , wove or spun, how prepared for dyeing, i. 382. How impregnated with alumine, i. 383, 384. Logwood, its denominations and history, ii. 338 — 341. Nature and properties of its colouring matter, ii. 341 — 343. Colours dyed from it, with different bases or mor- dants, ii. 344 — 34/. Prune de Monsieur, and other purple and violet colours, how dyed from it, ii.347 — 351. Effects of various metallic and earthy bases on its colouring matter, ii. 351—356. Its colouring matter proved to be less durable on the basis of cop- per, than of iron, ii. 481— 483. The blue which it affords, with a basis of copper, is more fugitive M INDEX. upon wool or cotton, and, therefore, justly prohi- bited, ii. 454, 455. Logwood, prosubstantive blue and other colours, afforded by it upon calico, ii. 354, 356'. Lombard}' Poplar, yellow colour dyed from it, ii. 108. Loareiro, his mention of a plant which dyes green, i. 264, n. Maclachlan, Mr., his account of the Coromandel red from chay root, ii. 291. Macquer, his treatise on the dyeing of silk, noticed, liii. Madder, (rubia) supposed by Virgil to colour the wool of sheep feeding upon it, i. Q2. Its different species, and their history, ii. 221 etseq. Madder, Dutch, (rubia tinctorum) long cultivated in Zea- land, ii. 221. How prepared there, ii. 223,224. ■, different colouring matters afforded by it, ii. 224, 225. Their different degrees of solubi- lity by water, ibid. Means and methods of dyeing wool and woollen cloth therewith, ii. 226—235. Effects produced upon its co- louring matter with different bases, ii. 234, 235. Its affinity to wool, ii. 31,32. Co- lours the bones of animals eating it, ii. 232, 233, and n. , its limited use in dyeing silk, ii. 235. •- ■ , its great utility in dyeingcotton and linen, ii.235. How applied in calico printing, ii. 236— -241. Different methods of employing it for dying cotton and linen generally, ii. 241—245. Madder, Turkey, (rubia peregrina) its history, ii. 245, 246* Its application for dyeing the Turkey red, ii. 247—277- Theory and different me- thods of communicating the Turkey red dye, ii. 247—2/0. The author's observations and experiments in regard to this dye, ii. 2/0— 2//. .Mahogany tree, the use of its bark for dyeing, ii. 363. INDEX 507 Manchineel tree, its acrid juice gives a black stain, i.312. Manganese exhibits various colours with water of different temperatures, i. 18. , the sulphate of it, imparts lasting colours to calico if impregnated with deoxygenating matters, i. 334. Manganese, added to sulphate of indigo, instantly destroys its colour, i. 233. Explanation of this fact, ibid. note. Mangrove tree, (vhizophora) history of it, ii. 358—360. Uses of its bark in dyeing, ii. 360 — 362. Manjith, or mungeet, a species of rubia, ii. 2/8, et seq. Mapile, the scarlet flowering, uses of its bark in dyeing, ii. 360— 485. Maz>eas, 1'Abbe, quoted concerning East Indian calico print- ing, i. 350. ■ , his experiments and reasonings in regard to the Ma- labar and Turkey reds, ii. 286—289, n. Mercury, its oxides relinquish oxygene so readily, that stains given by it have soon disappeared by a revival of the metal, one instance only excepted, i. 333 and n. Metals, (properly so called) their oxides, so far as they have been tried, were all found capable of serving as the bases of adjective colours, and some of them of also giving substantive colours, i. 338,-392. Mirrnosa juli flora affords good ink, ii.448. Used in Mexic® for dyeing black, ii. 484. Mordants, origin and application of the term, i. 342, 343. Methods of applying them in calico printing, i. 362, 303,376,377; alsoii. 1/5, .176, 17:1— 181. And of afterwards removing their superfluous parts by cleansing, &c. i. 363, 364, 378 j also ii. If6, J 77. 182 — 184. Mor'inda cilrifolia, a substitute for madder in Bengal, ii. 30S. Methods of employing it, ii< 309—31 1. The author's experiments with, roots supposed to have been taken from it r ii. 31 1-— 313. Monas tinctoria, or dyer's mulberry, improperly called old fustic, its history and uses in dyeing, ii. 103--- 508 INDEX. 106. Means employed by Chaptal to im- prove its colour, ii. 10(3. Myrobalan tree, (terminalia chebula) its fruit used in East Indian calico printing, i. 351 and n. They produce a full and lasting black with iron, and a yellow with alum, i. 352, n. also ii. 3/1. Experiment made with them, ii. 479, et seq. Newton, Sir Isaac, his doctrine of light and cojours, as delivered in the second book of his Optics, admitted, i. p. 1—4. His opi- nion that the colours of bodies depend on the sizes and densities of 'their parts, contested, i. p. 5—30. Nicaragua, or peach wood, its history and uses in dyeing, ii. 332, 333. Nickel, a green colour produced by itshydrated oxide, i. 336. Nyctanthcs arbor tristis affords a beautiful orange dye, i. 280. Oaks, American, (not including the quercitron; for dyeing, ii. 364. ■ , Michaux's history of them, ii. IIS, n. Olive green colour, several vegetables afford it with iron, ii. 3?5. Oil?, consisting of calca/eous earth and soda, employed in In- dian calico printing, i. 354. Orange colours, how dyed, ii. 3/8—380. Orchall, (Lichen roccella) its history and extensive employment in dyeing by the Greeks and Romans, i. 291—294. Methods employed by the moderns to produce and ail^l^^ Jfcjutilu! colour, i 295, et seq. See also * influences the production and changes 36—52. 62, 63. 79, 80. effects upon colours are not an indication or'measure of those which atmospheric air Wj^uld produce upon them, i. 68— 71. It de- woys colours by a peculiar agency not result- ing from oxygene, i. 75, 76. The author's oxp«timents therewith, i. 76"-79- INDEX. 509 Pallas, Prrofessor, quoted concerning the dissolution of indigo, i.. 219, n. Papillon,, Mr., his process for dyeing Turkey red, with obser- vations upon it, ii. 247 — 26l. Paraguayan bark, its use in dyeing, ii. 37 1 » 372. Percival,, Dr., failed in attempting to dissolve iron by a decoc- tion of galls, ii. 3Q8, n. Petty, SiirWm., his apparatus to the history and common prac- tices of dyeing, noticed, xlvii. Peysonntel, Dr., his account of naked snails affording purple, i. 161. Pinus ab)ies Americana, see Hemlock spruce. Piso, qiuoted, respecting gardenia genipa, i. 255. PJatina, colours afforded by it, and particularly a durable blood colour, discovered by the author, i. 331—333. Pjiny, qiuoted, respecting barbarous nations who painted thejr sUcins, xix j and the colours dyed by the transalpine Grauls, xxi, n. also concerning the Seres and their cot- ton, i. 93 ; and concerning silk and silk worms, i. 94, g:5 ; and the cotton of Upper Egypt, i. 105 j also con- cterning the Tyrian purple, i. 122 — 127. 130. ; and concerning indigo, which he aptly distinguishes by its Iteautiful purple smoke, i. 242, 243. Pliny's .account of Egyptian calico printing, i. 3/4 and n. and of ink, ii. 424 — 427. Poerner's.* observations on Saxon blue, i. 232 j and on the dyeing of black, ii. 456. Poivre, mis mention of a green indigo, i. 264. Polwhekc, Mr., his extravagant notions concerning the Tyrian purple, i. 129. 130, n. Polygonum!, several species of it for dyeing, ii. 356, 35/. Prinsep, Mr., a specimen of green indigo given by him to the author, i. 264, 265. Privet bterries, their colouring matter, ii. 3' t Procopiuis, quoted, respecting silk, i. 96. given • j^ ^$p v&f^m ■ 5ia INDEX. Prussian blue, its discovery, &rc. ii. 60, 6l. Means and me- thods of producing it, ii. 6*1, 02. Its colou-ing matter improperly called Prussic acid, 63. Dis- coveries of Scheele, Berthollet, and Proust,, re- specting it, ii. 63, 64. Solubility of its co- lourable part by potash, soda, and ammonia, and by their carbonates, which last also dissolve so •much iron, that a blue colour may be repro- duced by any of the acids, ii. 65, 66. But cms- tic alkalies only dissolve so much iron na i? ne- cessary to enable the red oxide of that metal to reproduce the blue colour, ibid. Pure colour- able matter, or simple Prussiate, first obtained by Scheele, ibid. This is easily decomposed, ur.less united to so much black oxide of iron as will convert it to a colourable but colourless Prus- siate, ii. 67. The latter mixed with green sul- phate of iron, becomes blue only when it has absorbed or acquired oxygene, ii. 67, 68. Cu- rious illustration of this fact, ii. 69, /O. Prussian blue, its unequalled beauty occasioned the endeavours of Macquer, Menon, Roland, d'Apligny, and Berthollet to employ this colour in dyeing, ii. /O---76. Observations on these endeavours, with experiments by the author, i. 76 — 80. He discovers a mistake made by Berthollet, winch the latter acknowledges, i. 80, 81. Prussian blue, beautiful green, dyed from it and from quercitron bark upon woollen cloth, with a fine illustration of the elective attractions of bases for particular colouring matters, ii. 81 and n. Other experi- ments to ascertain the affinities and effects of Prussian colouring matter, ii. 85---9O. Prussian colourable rnatter, or simple prussiate, the author's discovery pf a beautiful and lasting colour, (now called prussiate of copper,) produced by it with the INDEX. 511 basis of copper, and applicable to calico, &c. ii. 91. 93. Other colours produced by the simple prussiate, with solutions of cobalt, mercury, and gold, ii. 94. Purple, Tyrian, its history and wonderful properties, i. 120, et seq. Different shell fish producing it, particularly the murex and buccinum, i. 121 — 125. Varieties of this colour, and their names, i. 125 — 128. Accounts of its first discovery, i. 1 28 — 130. , thought to be most pleasing to the Gods, i. 131. Em- ployed to distinguish the Kings, Consuls, and higher magistrates of Rome, and afterwards appropriated ex- clusively to the Imperial family, i. 131. The dyeing of it permitted only to particular persons, i. 132 j and the knowledge of it lost in the 12th century, ibid. Re-discovered in the buccinum, by Mr. Cole, (an. 1683,) and his experiments therewith, i. 133 — 136. Excited the admiration of Charles the lid, ibid. , discovered afterwards in France by Jussieu, and by Reaumur, i. 136, 137. The latter's experiments there, 137—141. ■■' , discovered afterwards (in the purpura) by Duhamel 3 and his experiments therewith, i. 141— -144. Obser- vations upon all these experiments, i. 145--»146. , found by the author in the buccinum lapiilus from South Wales j with his experiments, completely elu- cidating the curious phenomena which attend the pro- duction and changes of this colour, and affording a signal instance of colourable matter, passing from yel- low to green, blue, purple, and crimson, by propor- tionate separations of oxygene, (through the agency of light,) as the colourable matter of indigo, on the other hand, affords one, of similar though less extensive changes, by proportionate acquisitions of oxygene, i. 146—158. ■, the odour of garlic which accompanies the production - ■ SSESBBBB wmmm m ■ ■■■■J 512 INDEX. of this colour, indicates phosphorus, which is then se- parated, in combination with oxygene, i. 155. Purple, other shell fish producing it, in different parts of America, i, 158 — 160. Purple and violet colours, how dyed on wool, silk, cotton, and linen, ii. 382—386. Quercitron Bark, ii. 1 12. Why so named by the author, ibid. Natural history of the tree which affords it, ibid, and n. Its uses in dyeing discove-ed by the author, and vested in him for a limited term, by act of Parliament, ii. 113. Bill to prolong the said term, passed by the House of Commons, but lost in the House of Peers, ibid, and note. ■ ■ -, methods of preparing it for dyeing, ii. 115— 117- Its colouring matter hew extracted, ii. 117, 118. Varieties of the quercitron bark, ibid, and n. Effects of chemical agents upon its colouring matter, ii. 120, 121. , t its application for dyeing wool and woollen cloth upon the basis of alumine, ii. 121 — 128. ■ ■ ' ■ ■ ■, its application to wool, &c. upon the basis of tin, ii. 128 — 142. , its application*to wool, &c. with the basis of copper, ii. 144. — — — — , its application to wool with the basis of iron, ii. 144, 145 ; and with other metallic bases, ii. 145, 146. — — 1 , its application for dyeing silk with different bases, ii. 146—148. v — — , its application for dyeing linen and cotton generally, upon the aluminous and other earthy and metallic bases, ii. 148—1/4. _ , - , its application for calico printing, ii. 1/4-— INDEX. 513 201 . Great advantages which have resulted from thus employing it instead of weld, ii. 188—201, and n. 217— 219. Qucrciitroti Bark, Prosubstantive yellow, and other colours afforded by it, 201 — 21 7. ■ , concluding observations respecting it, ii. 217—219. Ram, Mr., his MS. account of the red dyed from chayroot, ii. 297. Rouwolfla canescens, the juice of its berries used as an ink, and to stain linen, i. 312. — — , other species of it, afford lasting black stains to linen, &c. i. 313. Reaumur, his fruitless attempt to explain the production of purple from the buccinum, mechanically, i- 138. Rennell, Major, his testimony concerning the early intercourse between Hindostan and Egypt, i.348, 349. Rhamnius intfectorius, producing French or Turkey berries, and their yellow colour, ii. 106, 107, and n. Rhizopihora mangle, ii. 358 — 362. — gymnorhiza, ii. 362, 363. Rhus cotinus, or Venice sumach, called young fustic, its uses in dyeing, ii. 100. vernix, gives a lasting black str.in to linen, as do several other species of this genus, i. 30/. Riz, Mr. David, fallaciously pretended to obtain a colour equal to that of cochineal, from the cactus cochini- lifer, i. 473, n. Roard, M., his method of separating the natural gummy varnish from silk, i. 99, 100. — — . preparing wool for dyeing, i. S6. Rock Moss, see lichen and orchall. Rottleria tinctoria, its use in dyeing silk, ii. 314, 315. Roxburgh, Dr., his account of the silk of the phalena paphia, i.98. Vol. II. l 1 p^^^p^ ^^^^^^ y&m w^.w?$^m m 514 IND^X. Roxburgh, Dr., his account of the fermentation of incigo plants, i. J 74, et seq. ■ — — experiments and reasonings concerting the production of indigo, i. 1/4 — 184, anc n. •, adopts the author's opinion of the cause of its blue colour, i. 184. ■ — , his account of lac, ii. 10 — 12. Proposes to extract and concentrate its colour, ii. 13. Eubia manjith, or East Indian madder, its history, &c. ii. 2"8, 279- Affords a brighter red than any otier species of madder, though less durable on col- ton, ii. 2/(), 280. May he employed vith cochineal for dyeing scarlet, ibid. Colours produced by it with different bases, ii. 281, Its importation deserves encouragement, ibid. Rumford, Count, his experiments to revive gold from its solu- tions, i. 324. Safflower, its history, i. 286, 287. Means and. ways to lye with it a beautiful pink or rose colour on muslin, i. 287 — 28.Q. And to obtain from it a beautiful paint, (rouge vegetale,) for the human face, ibid Snnguinaria canadensis, or Canadian blood root, ii. 314. Sappan wood, how employed for Indian calico printing, i. 3L5. -■ , its history and uses in dyeing, ii. 329 — 331. Saunders, Mr., his account of lac, ii. 6 — 10. Saunders, red, ii. 336. Saw wort, (serratula tinctoria,) its use in dyeing yellow, ii. 107, 108. Saxon blue, history of its discovery, &c. i. 226. Theory of its colour, ii. 234, n. See indigo. Scarlet of the ancients. See kermes. Scarlet of the moderns. See cochineal. Scarlet, compounded by the author, from the rose colour of cochineal and the yellow of quercitron bark, i. 458 . Its advantages, i. 46l. 479, 480. 487—495. ■' ■. 1—, compounded from cochineal and madder, i. 495, 4p6\ and from cochineal and rubia manjith, ii. 260. INDEX, 515 Scarlet cotton, brought from China by the late Sir G. Staunton for the author, account of it, i. 286, n. Scheffer's method of applying the scarlet dye to cotton, i.536. Semecarpus anacardium, (oriental marking nuts,) how em- ployed, i. 308—310. The author's experiments with their black juice, ibid. Sennebier, bis account of the effects of solar light on colours, i. 47—51, GO, 61. Sepia, or cuttle tisb, and naked snails ejecting coloured fluids, i. 161—163. , an account of this wonderful genus, and their ink, ii. 430— 432, n. Silk, compared with wool and linen, i. S3, 84. Its history, structure, and properties, i. 92 — g7. Its varieties as pro- duced by different insects, i. 77—79- Means of sepa- rating its natural varnish, i. gg, 100. Its attraction for colouring matters, i. 101. , how impregnated with the aluminous basis, i. 384, 38Cf,n. , how dyed with cochineal, i. 531— -534. Silk, from the eggs of spiders, i. lol, 102. Silver, colours afforded by it, like those from gold and platina, require a partial revival of the metal, which may be promoted by the sun's rays, i. 327. And by substances attracting oxygene, i. 328. The latter applied to linen, enable it to decompose nitrate of silver, and acquire indestructible violet and black stains, i. 329. Marking ink produced in this way, ibid. n. Sophora, a sspecies of it for dyeing yellow, ii. 110, 111. Stephens, Mr., produced in Bengal, an extract of the colouring matter of lac, since called lac lake, ii. 17. The author's opinion of it requested on behalf of the India Company, ii. 1/ — 19. Sulphuric acid, its action upon indigo, i. 226—230. Sumach, elm leaved, (rhus coriara) its properties and uses in dyeing, ii. 101 — 103, m£m&m^ m& 516 INDEX. Tannin, is more frequently a constituent part of acerb or astrin- gent vegetables, than the colouring matter which pro- duces a black with iron, ii. 406. It differs in its pro- perties, that contained in galls, &x. becoming black with iron, but not that in the quercitron oak, the red mangrove, the mimosa catechu, and other vegetable* which tan skins efficaciously, ii. 403. Tartar, crude and cream of, their use in impregnating wool with alumine, i. 385. Terminalia chebula, see myrabolan tree. vernix, affords the black varnish of China, i. 3 12. Thenard and Roard, their experiments to ascertain the effects of the ordinary preparation of wool for dyeing, i.e. by boiling it with alum, and cream of tartar, (supertartrate of pot-ash) i. 386—389. They conclude from experi- ments, that solutions of tin are not decom- posed by wool boiled therein, i. 300, 30 1 . , their memoire on the dyeing of scarlet examined, i. 519 — 524. Tin, its qualities as produced in different countries, and their comparative values for dyeing, i. 505. Its adulterations, how detected, i. 505, 506. ■ - , nitro muriate of it, how commonly produced, i. 506, 507". It is not as modern chemists pretend, a muriate only of this metal, i. 507 — 509. Ammonia results from .the production of it, i. 509, 510 « - - -, solutions of this metal for dyeing, ought io contain acid not saturated therewith, i. 510 — 512. Reasons why an excess of acid is useful, ibid. « ■ > appearances and effects of a solution of this metal by muriatic acid, with an explanation thereof, i. 512 — 514. How dissolved most advantageously by muriatic acid, and how chrystallized, i. 514, 515. May be safely emplojed as a mordant, if prepared with an excess of acid, i. 515. n. 518, n. Muriate of tin supposed, when recently pre- * j V*" INDEX. M7 pared, to be at the lowest degree of oxygenation, i. 51 6. Is not, as Pelletier supposes, most useful in dyeing, when most oxidated, ibid. On the contrary, solutions of tin generally are found, by the author, to act most beneficially in exalting colours when but Utile oxygenated, i. 516, 5\"J. Tin, observations concerning the muriate of this metal, and its effects in dyeing scarlet with cochineal, i. 462 — 460. Experiment made with it on a large scale, i. 466—471. Tin, murio«nitrate of, an experiment made with it also on a large scale, i. 472—475. Tin, when dissolved by the conjoint action of sulphuric and nitric acids, reduces the crimson of cochineal Jo a salmon colour, i. 481, and n. This evil obviated, by mixing cream of tartar with these acids before the solution, ibid. Tin, in combination with the acid of tartar, makes the colour of cochineal incline to yellow, ibid. — — , murio-sulphate of this metal, a new mordant, first em- ployed successfully by the author in dyeing scarlet, i. 482 —•"487. Jts cheapness, and other advantages*, i. 483 — 486, 487, n.518, n. Tin, observations on the effects of various solutions of it in dyeing with cochineal, especially in regard to the diffe- rences resulting from the different degrees of oxygenation given to the metal, i. 474, n. 497 — 505. Tin, its oxyde as a basis, generally exhibits adjective colours with their utmost brightness and lustre, i. 392. Tin, solutions of it, improve the colour of madder on wool f ii.2'29— 231. Turmeric, its use as a substantive yellow, i. 276 — 279. Tyrian purple, see purple Tyrian. Vauquelin, his account of the preparation of wool for dyeing, i. 86. VitaHs, Professor, his account of the methods of dyeing Turkey red at Rouen, with observations, &rc. ii. 248 —264. . -, his method of dyeing black on cotton, ii, 47i . SBBBB jEB - -&3&$0m^ "If?' B I 5!S INDEX. Walnut, the properties and uses of the colouring matter of its rinds, &c. for dyeing, i. 306 ; and ii. 36/, 368- Weld, (resida luteola) probably the lutum of Virgil, ii Q5. Varieties of it, and their uses for dyeing yellow with different bases, and in calico printing, ii. 95—09. "Williams, Br. Richard, obtained a grant of 20001. for a yellow from weld, ii. 09. Woad, its history and means of obtaining it from the Isatis tinctoria, i. 166, 167. Additions to its history, i. 251 —253. Wool, its peculiar nature and structure, i. 82—92. Its attrac- tion for colouring matters, i. 84. Its difference in qua- lity, colour, &c. i. 85— -9J. Methods of scourir.g it, i. 86, 87. How impregnated with the aluminous bases, i. 384, 385. Woollen cloth, method of dyeing it topically or partially, -ii. 135. Yellow, highly esteemed by the ancients, but appropriated to the use of females only, ii. 95. - , several vegetables capable of dyeing it, ii. 95 — 111. Xanthoxylum clava Herculis, or Japan pepper tree, i. 2SO. Young, Dr. Thomas, his observations on the Newtonian theory of colours, i. p. 11. n. THE END. Printed by G. Sidney, Northumberland Street, Strand.