Digitized by the Internet Archive in 2015 https://archive.org/details/experimentsonbleOOhome EXPERIMENTS O N BLEACHING. By Francis Home, M. D. Fellow of the Royal College of Phyficians in Edinburgh. Tav yocp evrciv uyctBav y.cci xotkoiv vSsv, ctno aw* y.cci ntifJLt'k&cio Q&t SiSocto-i* avQpvTroi:, Prod, de Hercu!, EDINBURGH: Printed by Sands, Donaldson, Murray, & Cochran* For A. Kincaid and A. Donaldson. MDCCLVL ADVERTISEMENT At the defire of the Honourable Board of Truftees for the improve- ment of flmeries and manufactures in North Britain^ the following treatife was compofed, read in dif- ferent le&ures, and the experiments, fo far as it was poflible, were per- formed before the bleachers of this country. It is now publifhed in confequence of a petition prefented by the bleachers to the Honourable Board of Truftees. x C V to 3 A general plan of the work. PART I. SEC T. I. Connexion of chymijlry with the arts, SECT. II. Different practical methods of bleaching. PART It SECT. I. Steeping. SECT. II. Bucking and boiling, or the application of al- kaline lyes. SECT. III. Alternate watering and drying. SECT, t v j SECT. IV. Souring, or the application of acids. SECT. V. Hand-rubbing with foap and water j rubbing- boards. PART III. SECT. I. Blue pearl ajhes. SECT. II. White pearl ajhes. SECT. III. Mufcovy or blanch ajhes. SECT. IV. Cafliub ajhes. SECT. V. Marcoft afhes. SECT. VI. Method of manufaBuring thefe ajhes at home. PART IV. SECT. I. The natural effeffis of thefe ajhes, and of other bodies, on unbleached cloth. SECT. IL Of the caufe and tjf efts of hard water, and the methods of foftening it. SECT. III. The effects of Jleel and coal waters on cloth, and the cure. SECT. IV. Some conf derations with regard to the further improvement of the linen manufacture. EXPERIMENTS o N BLEACHING. PART h SECT, L Connection of chymijlry with the arts. Manufactures are to a country, what aliment is to the human . body. They fupply all waftes ; hinder a nation from preying on itfelf ; give it vigour for neeeflary du- ties diffufe the look of health and happi- nefs over its face ; and lay up a ffcore of ftrength for extraordinary exertions of its power. A wife government will no more negledt, or overlook the manufactures of a country, than a wife phylician the diet of one committed to his care. A Let 2 EXPERIMENTS PartL Let us take a curfory view of the differ- ent methods neceffary to be employed in eftablifhing manufactures y for without all, or moft of thofe, it is in vain to expeCt that thefe will ever arrive at any degree of per- fection. We may reduce all the different ways made ufe of to promote manufactures, to two general fources ; the wife regulations of the government, and the united efforts of the people where thefe manufactures are e- ftablifhed. The influence of the government confifts in encouraging home manufactures, by granting protection, privileges, immunities, and bounties 5 to fuch as carry them on j by taking off all duties on the materials ufed in them - y by eftablifhing proper truftees to have the infpeCtion of them, and companies with fuitable privileges > by fettling proper funds to be diftributed in rewards to thofe who excel , by not making it too burthen- fome and expenfive for the manufacturers to obtain Sea. I. ON BLEACHING. 3 obtain good laws ; and by a proper regula- tion of the fafhions at their fource. But all thefe advantages are of fmall a- vail, if a ready market is not opened : for it is an axiom in trade, That manufactures increafe only in proportion to the demand for them. Here then will the wife politi- cian be again difcovered, in difcouraging all foreign manufactures of the fame kind, by prohibitions, or high duties equivalent to them. Thanks to the prefent government for their great regard and attention to the ma- nufactures of North Britain. More has been done for it in this way, within thefe few years, than in all thofe ages which went before. In after times it will be the diftin- guiihing character of the prefent, That ma- nufactures and induitry were encouraged in North Britain, nay, introduced into its re- moteft parts. What advantage this will be to South Britain, is evident to one who confiders, that the greateft part of our gains mull at laft centre there ; and that as much A 2 linen EXPERIMENTS Parti. linen was manufactured, even in the con- fufion of the year 1745, as in any of the preceding. This faCt merits the utmoft at- tention ; and fliows, that there is not a more proper and effectual antidote againft rebel- lion, than induftry and manufactures. It is not enough that a government makes wife regulations. The leading peo- ple of a country muft lend their united af- fiftance. From them alone a true fpirit takes its rife, and diffufes itfelf by degrees over the generality of a country. The lower ranks of people are capable of following, though not made for leading. To difcover the good effeCts of a general fpirit in people of rank, let us caft our eyes on a neighbour- ing ifland. What well-judged regulations with regard to the whole progrefs of the linen manufacture ! what attention and en- couragement to every ufeful projeCt ! what union and fpirit in carrying it into execution ! what a judicious diftribution of public and private bounties ! what a wife inftitution is their linen-hall in Dublin, in affording a conftant market for foreign merchants, and a Sed.I. ON BLEACHING. 5 a conftant check to the frauds of private dealers ! To their eternal honour be it faid, no nation ever made a better ufe of fo bad a commonalty. They turn even the vices of their nation to the public benefit. Their foundling-ho- fpital, ere&ed for the reception of thofe children, whom parents either cannot main- tain, or do not chufe to own, is become a feminary of induftry. Of 1500 children, thofe who are capable from their age, are employed chiefly in fpinning flax and wool. I had the pleafure lately to fee 1 50 girls, between fix and twelve years old, fpinning with both hands. A Scots woman employ- ed to teach them, has a falary of L. 30 a- year fettled on her by the truftees. It is no difficult matter to forefee what great advan- tage this hofpital will be to that nation in a few years. Thefe children, when grown up, will fpread themfelves over the country, teach others, double the quantity of yarn, reduce its price, and put it in their power to underfel others. Such a wife regulation in this country, would be the means of faving the 6 EXPERIMENTS PartL the lives of many innocent children, and many unhappy mothers, and turn to fome national advantage what we cannot perhaps altogether reftrain. I fhould be guilty of an injuftice to this country, were I not in a public manner to own the many obligations which we lie un- der to the Honourable board for the im- provement of fifheries and manufactures in Scotland. Thefe gentlemen, fince they were firft conftituted in the year 1727, have, with unwearied and difinterefted zeal, contributed in a very great meafure to raife, and diredt a fpirit of induftry among us, by their own example \ by their experience ; by adopting the experience of our neigh- bours \ and by diftributing, with great pru- dence, thole fmall funds intrufted by the government to their management* For their reward they (hare the bleffings of the induftrious poor. The great advantage of the linen manu- facture, in which point it is allowed to have the preference to the woollen, arifes from the Seal. ON BLEACHING. 7 the many changes which that commodity undergoes, before it comes to market 5 and confequently its employing many hands. But this advantage makes it more liable to fuffer from ignorance, or fraud j and makes it require more care. There is no part of the manufacture on which its character fo much depends, as on its management in the bleachfield. On that circumftance depend its two effential qualities, colour and ftrength. Of fuch confequence to the linen trade is that part of its progrefs, that I may fafely venture to affirm, without affuming any title to the fpirit of prophecy, that the linen manufacture of Ireland, from this caufe a- lone, will, nay perhaps has already, come into fome difrepute ; and muft at laft fuffer ? if the Irijh do not alter their method of bleaching. We, in this country, have generally fol- lowed a better method j but as that feems to be owing to our vicinity to Holland, and not to a greater knowledge in the art, we can claim no merit from it. That an art fo ingenious, fo difficult, depending fo much 8 EXPERIMENTS PartL much on a nice judgment, confifting of fo many different parts, and withal, of fuch moment to thefe nations, fliould have lain fo long neglected, affords matter of furprife. Thofe bred to this art are capable of fur- nifhing materials, but are incapable, as it would feem, of reducing it to certain fixed principles. Some knowledge, befides what the art gives, appears neceffary even to the art itfelf. This opens another fource for the improvement of manufactures, viz. the confideration of thofe whofe genius or edu- cation has led them to the ftudy of fciences and arts, on which thefe manufactures, in a great meafure, depend. There is no art of fuch extenfive ufe as chymiftry. If chymiftry was once too wild and ex- travagant, it has been for many years too tame and confined. It feldom ventures fur- ther than the compofition of a medicine, as if that were all the fervice it could be of to mankind. But chymiftry is of much great- ter extent. It claims as its own, all changes that are carried on by fire, or difiolvents j it looks upon the operators, as entirely un- der Seal. ON BLEACHING. 9 der its guidance ; the operations to be ac- counted for only on its principles 5 and the hopes of further perfection in the art, fo far as human judgment is concerned, to reft on it alone. This, and nothing lefs, is true chy- miftry ; and may be called Chemia philofo- phica, or Philofophical chymiftry, as Boyle has termed it ; or Univerfal chytnijlry, to ufe Dr Sbaw's expreffion, in diftindtion to the confined medical chymiftry. All arts, excepting thofe which regard the operations of the mind, may be diftin- guifhed into mechanical, chymical, or thofe which partake of both. The mechanical, or fuch as attain their ends by mechanical inftruments, are few in refped: of the chy- mical, which depend on fire and diflbl- vents. In the latter clafs, I rank cookery, tanning, dying, fmelting, gilding, fugar- refining, confedtionery, baking, brewing, making of fait, fermenting of wines and vinegar, the different metallurgic trades, diftilling, foldering, making of fiarch, glafs ? delf ware, china ware, &c. The mixed arts, which partake fomewhat of each, are, B agriculture, 10 EXPERIMENTS Part L agriculture, building, printing, making of mirrors, paper, &c. Let us take a view of the dependence Which thefe arts have on chymiftry. Dying cannot be carried on without it. The in- ftruments with which that art works, are, quick-lime, alkaline and acid falts, folu- tions of tin and iron in acids, and neutral falts, as alum, fal ammoniac, and tartarus vitriolatus. Without the affiftance of thefe falts, very few colours can be ftruck on ei- ther woollen, linen, or cotton 5 but v/ith their affiftance, all the colouring particles are feparated from the water in which they are diflblved, and fixed on the furface of thefe bodies. The durablenefs of colours, and their refiftance againft the effe&s of fun and moifture, are to be explained only from the properties of thefe falts. In the folu- tions and mixtures of chymiftry, many beautiful colours, which were never heard of in the art of dying, arife, are changed, or deftroyed. The art of tanning is a regular chymical procefs, Setf.L ON BLEACHING. n procefs, not to be underftood by thofe who are ignorant of its principles. What ac- count can the tanner give of his firft opera- tion, fteeping the hides in lime and water? The chymift will inform him, that the in- tention of it is not only to take oft the hair, but to diffolve the oleaginous particles by the affiftance of lime, that fo the paflages may be cleared for the next operation. The former mull be at as great a lofs to give a reafon why he fteeps his hides in water impregnated with oak bark, if the latter did not ftep in to his affiftance, and fhow him, that the infu* lion of bark, by means of its aftringent fait, diffolved by the water, hardens the animal fibres, and fhuts up all their pores, fo that water cannot pafs through them fo eafily as it did before. It is he alone who can ac- count for the different effects of the differ- ent methods of operating in making foft, bend or fhamoy leather. The cook, while he prepares a difh of foup, is in that fituation a real chymift. He operates with the fame agents the chy- mift operates with ; fire, and the diffolvent or B 2 menftruum 12 EXPERIMENTS Parti. menftruum water ; and with the fame de- iign, to diffolve fome part of the meat, and impregnate the water or diffolvent with thefe particles : but being ignorant of the other branches of chymiftry, he does not know what parts are diffolved by the water, how thefe parts are compounded, in what manner they may be feparated in greater quantity, or how the whole fibrous parts, nay the bones themfelves, may be diffolved into a liquor. One who joined this know- ledge to his practice, would certainly be a more compleat cook than what he was be- fore. Agriculture, again, is greatly indebt- ed to the powers of mechanics, the plough, harrow, and other inftruments, for open- ing and pulverifing the ground, in order that the plants may be able to pufh their roots to a greater diftance, that they may take in their food. But what is that food and nou- rilhment which is abforbed by the roots of plants, and without which it is in vain for them to extend their roots ? That queflion I may fafely venture to affirm is only to be anfwered Sethi. ON BLEACHING. 13 anfwered by a chymift. It is he alone who can fhow the nature and properties of that vegetable food ; it is he alone who can tell how it comes there naturally. Experience indeed has learned farmers, that certain fubftances frudlify the ground : but he, un- doubtedly, will be able to produce the greateft quantity of that food in the fhorteft time, who knows what it is, and how pro- duced. So true this is, that though dung is the moft common compoft, and has been ufed in all ages ; yet I may venture to affirm, that the chymift could teach the farmer many ufeful obfervations with refpedt to the management of dunghills. Farming can never be reduced to a regular art, till a far- mer arife acquainted with chymiftry. I know no trade which is fo entirely the objedl of chymiftry as bleaching, and none that has been fo little conlidered in -that light. For what are fteeping, bucking, fouring, wafhing with foap, alternate wet- ting and drying, but fo many procefles, that are carried on by thefe powerful chymical agents, heat and diffolvents ? What is the end i 4 EXPERIMENTS PartL end propofed, but the diffolving and carry- ing off, by the means of acid and alkaline fals, moft powerful menftruums, fomewhat which gives the cloth its prefent colour ? and what way more certain to carry off whatever is loofened, than the evaporation of water by heat, which is a fpecies of di- ftillation performed in the open air ? I find the moft fkilful bleachers under- ftand the general theory of their art tole- rably well j but being ignorant of the prin- ciples of chymiftry, cannot make the pro- per ufe of this theory, or apply their know- ledge to the advancement of their art. They know that alkaline falts diflblve oils, and that a fermentation is carried on „by fteeping, bucking, and fouring; but chy- miftry can alone teach them, that by cer- tain methods fermentations may either be quickened, and a great deal of time faved 5 or be checked, and much time loft j nay, perhaps the effedt not produced. But what the bleachers are moft defi- cient in, is a knowledge of the nature and properties Sect. I. ON BLEACHING. 15 properties of thofe alkaline falts, or aflies, as they call them, which they make life of. Experience has taught them, that thefe falts are to be ufed in different proportions ; but nothing lefs than a chymical inquiry can dif- cover their hidden nature. If this point was once afcertained, the theory of bleach- ing would reft on a more certain foundation than at prefent. For what certain theory can be eftabliflied with regard to the opera- tion of thofe aflies, w r hen we know not what thofe aflies are ? But this is not all the advantage we ex- pert to reap from an examination of this kind. What if thefe bodies are not Ample alkaline falts ? For ought we know they may not, but may be a compofition of differ- ent fubftances. And what if we difcover by chymical experiments their compofition ? If this happens to be the cafe, we may per- haps be able to make thefe aflies at a much cheaper rate in our own country, than what they coll us when imported from abroad. The inquiry is worthy of the utmoft atten- tion ; and if fuccefstul, cannot fail to be of great 16 EXPERIMENTS PartL great importance to this country. It cofts, as I am told, Great Britain and Ireland L. 300,000 for aflies every year. It is dif- ficult to fay to what a fum that commodity may amount 5 nay, it is imp.offible to allure ourfelves, that we will procure it at any price, when we are told, that the aflies were monopolized by two Dutch merchants three years ago, and retailed again to us at a double or triple price. Our manufactures could not have fubfifted during the late war with Spain , unlefs an order of the King and council had pafled, allowing the importation of SpaniJJj pot-aflies. Both profit and ne- ceffity contribute to quicken our induftry. For the benefit of the linen manufacture of this country, and of our neighbouring ifland, whofe interefis appear to be the fame, and ought always to be united againft their common competitors in trade, I have ap- plied what little knowledge I have in chy- miftry, and endeavoured to reduce the art of bleaching, hitherto variable and unfafe, to fome fixed principles, that it might not depend ■Sett. I. ON BLEACHING. v 7 depend on opinion, or on fuch experience as always dies with the pofleflbrs. Were I to make myfelf acquainted with an art of which I was before entirely igno- rant, I would naturally inquire into the common practice, or general method of o- perating in that art ; and then endeavour to difcover the defign and reafon of each ope- ration, that I might know, whether the method generally praftifed was the fitteft to attain the end propofed. I would certainly endeavour to get a thorough knowledge of the agents or inftruments made ufe of in the art 5 what was the befl way of procu- ring or making them at home ; and what were their effects when applied in the man- ner that the art diredts. I fhould at laft confider the impediments which the art meets with, and the methods of removing them. This is the plan of the following difquilition. I have begun with the general methods of bleaching, and defcribed thofe inoft approved of. An examination into each particular operation, its effe&s, the end pro- pofed, and the beft methods of accomplifh- C ing i8 EXPERIMENTS PartL ing it, follows. The nature and compofition of the different aflies ufed in bleaching ; the method by which thefe falts may be made as good at home as thofe imported from a- broad ; and their natural effedts, when ap- plied to cloth, fucceed. At laft is confi- dered that great impediment to bleaching, hard w T ater ; the method how the greateft degrees of it may be corrected, is fhown - y and, which is more ufeful to the bleacher, how the fmalleft degrees of it may be dif- covered, and fo fhunned. I have endea- voured to render the whole as ufeful to our linen trade as poffible. There is no way to promote the art of bleaching, which is entirely carried on by the operation of different bodies, but that of experiment : and that alone I have fol- lowed. Every other method of advancing the arts is now juftly derided. It is indeed laborious to the undertaker, and cannot be accomplished without accuracy and length U)ii^£vp(Tov %wscrio£ Soku triBvuyiu.cc re xec* tpyov sivtzt. Af to roc vfjAi^yv. »; t&qs iftpyctpJttrQut uirMrJi', IIIUQKPATOTS trtpt n^»:* ing, to prevent the cloth from riling du*~ ring the fermentation which enfues. A- bout fix hours after the cloth has been fteeped in warm water, and about twelve in cold, bubbles of air arife, a pellicle k formed on the furface of the liquor, and the cloth fwells when it is not prefled down. This inteftine motion continues from thirty- fix to forty-eight hours, according to the warmth of the weather ; about which time the pellicle or fcum begins to fall to the bot- tom. Before this precipitation happens, the cloth muft be taken out ; and the proper time for taking it out, is when no more air- bubbles arife. This is allowed to be the juftejft guide by the moll experienced bleachers. The cloth is then taken out, well rin~ fed, difpofed regularly by the felvage, and .wafhed in the put-mill to carry off the loofe , duft. After this it is fpread on the field to dry : when thoroughly dried, it is ready for bucking ; which is the fecond operation. Bucking^ SeaiL ON BLEACHING. 25 Bucking, or the application of falts, is performed in this manner. The firft or mother lye is made in a copper, which we fhall fuppofe, for example, when full, holds 170 Scots gallons of water. The copper is filled three fourths full of water, which is brought to boil : juft when it begins, the following proportion of afhes is put into it, to. 30 lb. of blue, and as much white pearl afhes 5 200 lb. of Marcoft afhes, (or, if they have not thefe, about 3001b. of Cajhub)> 300 lb. of Mufcovy or blanch afhes ; the three laft ought to be well pounded. This liquor is allowed to boil for a quarter of an hour, ftirring the afhes from the bot- tom very often ; after which the fire is taken away. The liquor muft ftand till it has fettled, which takes at leaft fix hours, and then it is fit for ufe. Out of their firft or mother lye, the fe- cond> or that ufed in bucking, is made in this manner. Into another copper, hold- ing for example 40 Scots gallons, are put 38 gallons of water, 2 lb. foft foap, and 2 gallons of mother lye ; or, for chcapneft, D m 26 EXPERIMENTS Part L in place of the foap, when they have lye which has been ufed to white linen, called white-linen lye, they take 14 gallons of ft, leaving out an equal quantity of water. This is called buchng-lye. After the linens are taken up from the field dry, they are fet in the vat or cave, as their large veflel is called, in rows, end- ways, that they may be equally wet by the lye; which, made blood- warm, is now thrown on them, and the cloth is afterwards fqueezed down by a man with wooden fhoes. Each row undergoes the fame ope- ration, until the veffel is full, or all the cloth in it. At firft the lye is put on milk- warm, and after fianding a little time on the cloth, it is again let off by a cock into the bucking-copper, heated to a greater degree, and then put on the cloth again. This courfe is repeated for fix or feven hours, and the degree of heat gradually increafed, till it is at the laft turn or two thrown on boil- ing hot. The cloth remains after this for three or four hours in the lye ; after which the Sedt.IL ON BLEACHING. 27 the lye is let off, thrown away, or ufed in the firft buckings, and the cloth goes on to another operation. The cloth is then carried out, generally early in the morning, fpread on the grafs, pinned, corded down, expofed to the fun and air, and watered for the firft fix hours, fo often, that it never is allowed to dry. Afterwards it is allowed to lie till dry fpots appear before it is watered. After feven at night it gets no more water, unlefe it be a very drying night. Next day in the morn- ing and forenoon it is watered twice, or thrice if the day is very dry ; but if the wea- ther be not drying, it gets no water : after which it is taken up dry if the green is clean ; if not, it is rinfed, mill-wafhed, and laid out to dry again, to become fit for buck- ing. This alternate courfe of bucking and watering, is performed for the moft part from ten to fixteen times, or more, before the linen is fit for fouring ; gradually increafing the ftrength of the lye from the firft to the D z middle 28 EXPERIMENTS Parti. middle bucking, and from that gradually decreaiing it till the fouring begins. The lyes in the middle buckings are generally a- bout a third ftronger than the firft and laft. Souring, or the application of acids to cloth, is the fourth operation. It is diffi- cult to fay when this operation ftiould com- mence, and depends moftly on a length of experience. When the cloth has an equal colour, and is moftly freed from the fprat, or outer bark of the lint, it is then thought fit for fouring which is performed in the following manner. Into a large vat or vef- fel is poured fuch a quantity of butter-milk^ or four milk, as will fufficiently wet the firft row of cloth ; which is tied up in loofe folds, and preffed down by two or three men bare-footed. If the milk is thick, a- bout an eighth of water is added to it if thin, no water. Sours made with bran, or rye meal, and water, are often ufed inftead of milk, and ufed milk-warm. Over the firft row of cloth a quantity of milk and wa- ter is thrown, to be imbibed by the fecond t and fo it is continued till the linen to be fowl- ed SeaiL ON BLEACHING. 29 ed is fufficiently wet, and the liquor rifes o- ver the whole. The cloth is then kept down by covers filled with holes, and fecu- red with a poft fixed to the joift, that it may not rife. Some hours after the cloth has been in the four, air-bubbles arife, a white fcum is found on the furface, and an inte- ftine motion goes on in the liquor. In warm weather it appears fooner, is ftronger, and ends fooner, than in cold weather. Juft before this fermentation, which lafts five or fix days, is finifhed, at which time the fcum falls down, the cloth fhould be taken out, rinfed, mill-wafhed, and deli- vered to the women to be waftied with foap and water. < Washing with foap and water, is the fifth operation 3 and is performed thus. Two women are placed oppofite at each tub, which is made of very thick ftaves, fo that the edges, which Hope inwards, are about four inches in thicknefs. A fmall veffel full of warm water is placed in each tub. The cloth is folded fo that the felvage may be firft rubbed with foap and warm water length- , 3 o EXPERIMENTS Parti. length- ways, till it is fufficiently impreg- nated with it- In this manner all the par- cel is rubbed with foap, and afterwards car- ried to be bucked* The lye now ufed has no foap in it, ex- cept what it gets from the cloth ; and is e- qual in ftrength to the ftrongeft formerly ufed, or rather ftronger, becaufe the cloth is now put in wet. From the former ope- ration thefe lyes are gradually made ftrong- er, till the cloth feems of an uniform white, nor any darknefs or brown colour appears in its ground. After this the lye is more ipeedily weakened than it was increafed ; fo that the laft which the cloth gets, is weak- er than any it got before* But the management of fours is differ- ent y for they are ufed ftrongeft at firft, £nd decreafed fo in ftrength, that the laft four, confidering the cloth is then always taken up wet, may be reckoned to contain three fourths of water. From the bucking it goes to the water- ing. Sedt.IL ON BLEACHING. 31 ing, as formerly, obferving only to overlap the felvages, and tye it down with cords, that it may not tear ; then it returns to the four, milling, wafhing, bucking, and wa- tering again. Thefe operations fucceed one another alternately till the cloth is whiten- ed ; at which time it is blued, ftarched, and dried. This is the method ufed in the whiten- ing our fine cloths. The following is the method ufed in the whitening of the coarfe. Having forted the cloths according to their quality, they are fteeped in the fame manner as the fine, rinfed, wafhed in the mill, and dried before boiling. In this procefs, boiling fupplies the place of bucking, as it takes lefs time, and confe- quently is thought cheapeft. It is done in the following manner : 200 lb. Cajhuh afhes, 100 lb. white Mnfcovy> and 30 lb. pearl afiies, boiled in 105 Scots gallons of water for a quarter of an hour, as in the procefs for the fine cloth, makes the mother or firfl lye. 32 EXPERIMENTS Parti. lye. The cloth-boiler is then to be filled two thirds full with water and mother lye, about nine parts of the former to one of the latter ; fo that the lye ufed for boiling the coarfe cloth, is about a third weaker than that ufed in bucking the fine. Such a quan- tity of cloth is put into the foregoing quan- tity of lye, when cold, as can be well cover- ed by it. The lye is brought gradually to the boil, and kept boiling for two hours % the cloth being fixed down all the time, that it does not rife above the liquor. The cloth is then taken out, Ipread on the field, and watered, as mentioned before in the fine cloth. As the falts of the lye are not exhaufted by this boiling, the fame is continued to be ufed all that day, adding, at each boiling, fo much of the mother lye as will bring it to the fame ftrength as at firft. The lye by boiling lofes in quantity fomewhat betwixt a third and a fourth ; and they reckon that in ftrength it lofes about a half, becaufe they find in practice, that adding to it half its former ftrength in frefli lye, has the fame effea: Se6l.IL ON BLEACHING. 33 effedt on cloth. Therefore fome frefh lye, containing a fourth part of the water, and the half of the ftrength of the firft lye, makes the fecond boiler, as they imagine, equal in ftrength to the firft. To the third boiler they add fomewhat more than the former proportion, and go on ftill increa- fing gradually to the fourth and fifth, which is as much as can be done in a day. The boiler is then cleaned, and next day they begin with frefh lye. Thefe additions of frefh lye ought always to be made by the mafter bleacher, as it requires judgment to bring fucceeding lyes to the fame ftrength as the firft. When the cloth comes to get the fecond boiling, the lye fhould be a little ftronger, about a thirtieth part, and the deficiencies made up in the fame proportion. For fix or feven boilings, or fewer, if the cloth be thin, the lye is increafed in this way* and then gradually diminished till the cloth is fit for fouring. The whiteft cloth ought al- ways to be boiled firft, that it may not be hurt by what goes before, E Tn 34 EXPERIMENTS Parti. In this procefs, if the cloth cannot be got dry for boiling, bufinefs does not ftop as in the fine ; for after the coarfe has dreeped on racks made for the purpofe, it is boiled, making the lye ftrong in propor- tion to the water in the cloth. The common method of fouring coarfe linen, is, to mix fome warm water and bran in the vat - y then put a layer of cloth 5 then more bran, water, and cloth ; and fo on, till the cave is full. The whole is tramped with mens feet, and fixed as in the former procefs. 1 000 yards of cloth, yard-broad, require betwixt 4 and 6 pecks of bran. The cloth generally lies about three nights and two days in the four. Others prepare their four twenty-four hours before, by mixing the bran with warm water in a fe- parate veffel ; and before pouring it on the cloth, they dilute it with a fufficient quan- tity of water. After the cloth is taken from the four, it ought to be well wafhed and rin- fed again. It is then given to men to be well foaped on a table, and afterwards rub- bed betwixt the rubbing-boards. When it comes Se6l.IL ON BLEACHING. 35 comes from them, it fhould be well milled, and warm water poured on it all the time, if conveniency will allow of it. Two or three of thefe rubbings are fufficient, and the cloth very feldom requires more. • The lye, after the fouring begins, is de- creafed in ftrength by degrees, and three boilings after that are commonly fufficient to finifh the cloth. Afterwards it is ftarch- ed, blued, dried, and bittled in a machine made for that purpofe, which fupplies the place of a calendar, and is preferred by many to it. This method ufed in the bleaching of our coarfe cloths, is very like that pradtifed in Irela?td for both fine and coarfe. The only material difference is, that there the bleachers ufe no other aflies but the kelp or Cajloub. A lye is drawn from the former by cold water, which diffolves the falts, and not the fulphureous particles of the kelp afhes. This lye is ufed till the cloth is half whitened, and then they lay afide the kelp lye for one made of Cajhub afhes. I am E 2 told 36 EXPERIMENTS. Parti. told that their moft fkilful bleachers have laid afide the ufe of the kelp afhes. Thus I have given a fhort Iketch of the modern, and moft approved practice of bleaching ; a fketch fufficient to condud: thofe who know a little, though not defigned to inftru£l thofe who are entirely ignorant. The practice is, no doubt, capable of great improvements. Some are afterwards at- tempted 5 others will be difcovered by time. It is our bufinefs to forward thofe difcove- ries, and to open the fpeedieft way for at- taining and divulging them. PART PART II. SECT. I. Steeping. IN the preceding hiftory of bleaching, we may obferve, that it naturally di- vides itfelf into feveral different branches or parts, all tending to give linen the de- gree of whitenefs required. How they ef- fectuate that, comes next under our confi- deration. If we can fettle this queftion, we fhall be able to difcover where the prefent practice fucceeds, and where it fails ; we fhall be able to fettle principles, by which the art may receive further improvement ; we fhall reduce it to a regular fcience. The general procefs of bleaching di- vides itfelf into thefe different parts, i. Steeping and milling. 2. Bucking and boiling. 3. Alternate watering and drying. 4. Souring. 5. Rubbing with foap and warm water, ftarching, and bluing. We fhall 38 EXPERIMENTS PartIL fhall treat of thefe different parts in their order. Green linen, in the different changes which it has undergone before it arrives at that ftate, contracts a great foulnefs. This is chiefly communicated to it by the dreffing compofed of tallow and fowen, which is a kind of flummery made of bran, flour, or oat-meal feeds. The firft thing to be done in the bleachfield, is to take off all that filth which is foreign to the' flax, would blunt the future action of the falts, and might, in unfkilful hands, be fixed in the cloth. This is the defign of ffeeping. To accomplish this end, the cloth is laid to fteep, or macerate, as chymifts call it, in blood-warm water. A fmaller degree of heat would not difiblve the dreffing fo foon ; and a greater might coagulate and fix, as will afterwards appear, in the body of the linen, thofe particles which we defign to carry off". In a few hours the dreffing made ufe of in weaving is diflblved, mixed with the waterj and as it had acquired fome Sedhl. ON BLEACHING. 39 lome degree of acidity, before application, it becomes a fpecies of ferment. Each fer- ment promotes its own particular fpecies of fermentation, or inteftine motion ; the pu- trid ferment fets in motion the putrefactive fermentation 3 the vinous ferment gives rife to the vinous fermentation ; and the acid ferment to the acetous fermentation. That there is a real fermentation going on in fteeping, one muft be foon convinced, who attends to the air-bubbles which immedi- ately begin to arife, to the fcum which ga- thers on the furface, and to the inteftine motion, and fwelling of the whole liquor. That it muft be the acetous fermentation, appears from this, that the vegetable par- ticles already in part foured, muft firft un- dergo this procefs. The effe&of all fermentations is to fet the liquor in motion ; to raife in it a degree of heat , and to emit air-bubbles, which, by canying up feme of the light oleaginous particles along with them, produce a fcum. But as the dreffing is in fmall quantity in proportion to the water, thefe effects are gentle and flow. The acid falls are no fooner 4 o EXPERIMENTS PartIL fooner feparated, by the acetous fermentation, from the abforbent earth, which made them not perceptible to the tongue in their former ftate, than they are united to the oily par- ticles of the tallow, which likewife adhere fuperficially, diffolve them, and render them, in fome degree, miffible with water. In this ftate they are foon wafhed off by the inteftine motion of the liquor. The confe- quence of this operation is, that the cloth comes out freed in a great meafure from its fuperficial dirt; and more pliant and foft than what it was. Whenever this inteftine motion is pret- ty much abated, and before the fcum fub- iides, bleachers take out their cloth. The fcum, when no more air-bubbles rife to fupport it, feparates, and falls down ; and would again communicate to the cloth great part of the filth, when the defign of this ope- ration was to carry it off. But a longer ftay would be attended with a much greater dif- advantage. The putrid follows clofe upon the acetous fermentation : when the latter ends, the former begins. Were this to take place, Sedt.1. ON BLEACHING. 41 place in any confiderable degree, it would render the cloth black and tender, as we fhall have occafion afterwards to fhow. Bleachers cannot be too careful in this article. The firfl queftion that arifes to be deter- mined on thefe principles, is, What is the propereft liquor for fteeping cloth ? Thofe ufed by bleachers are plain water ; white- linen lye and water, equal parts - y and rye meal or bran mixed with water. They always make ufe of lye when they have it ; a proof that they think it the beft. They fay it ferments moll. Were that really true* I would think the reafon fufficient. But; there may be a deception in the cafe, That lye is impregnated with much foul- nefs, which by rifing to the furface may make a thicker fcum, produce more air- bubbles, and give the appearance of a ftrong- er fermentation. The alkaline falts, which make part of its compofition, will attract the acid falts generated by the fermentation > and put a flop to their junction with the oils. In this view it may do harm. Oil the other hand, if the alkaline falts in it F are EXPERIMENTS PartlL are not compleatly faturated, they may be of ufe in uniting with, and carrying off the greafy particles of the tallow. Such oppolite and unfatisfadtory views are the common refult of theory, when we rely entirely upon it for a decifion. But fhall we reft this important queftion on no better footing than this ? Can we find no certain criterion to judge of the propereft liquor for fteeping linen ? The delign of the operation will afford us one. The end propofed by it is to loofen and carry off the fuperficial foulnefs of the cloth. That li- quor then which carries off moft of it, and makes the cloth lighteft, muft be the pro- pereft. Let us, by this teft, try thefe dif- ferent liquors. Exp. i. June 25. A web was cut thro* the middle into two pieces j one half of the piece, weighing 4 lb. 1 oz. was fteeped in milk- warm water 3 the other half, weigh- ing half an ounce more, was fteeped in old lye and water, equal parts, and of an e- qual degree of heat with the former. There Seal. ON BLEACHING. 43 There was fome little fermentation in the former, but none in the latter. They were taken out on the 26th, at eleven of the clock in the forenoon, and dried. Each of the pieces now weighed 3 lb. g\- oz. : fo that the old lye, by this experiment, ap- pears better for cleaning cloth than plain water, as the former takes out about an eighth part more than the latter. That I might compare the effects of bran with thofe of old lye, Exft. 2. I cut a web into two pieces, and put one part, weighing 5 lb. 1 oz. into bran and warm water ; the other, weighing 5 lb. was put into a mixture of old lye and warm water, a third of the former to two thirds of the latter. They lay forty-eight hours in thefe liquors ; during which time there was little or no fermentation in the old lye, but a confiderable degree in the bran and water. When dried, the former piece weighed 4 lb. 13X oz. the latter 4 lb. 11 oz. That in the bran and water had loft but 3t oz. but that in the old lye had loft 5 oz. F 2 That 44 EXPERIMENTS PartIL That I might make the fame trial on greater quantities of cloth, Exp. 3. I took fix pieces of cloth, near- ly of the fame finenefs, and containing twenty-live yards each. Two of thefe, weighing 20 lb. 1 oz. were fteeped in old lye 5 other two, weighing 18 lb. 15 oz. in bran and water ; the remaining two, weigh- ing 191b. 13 oz. in plain water. All thefe liquors were of an equal degree of warmth. Thefe lay for forty-eight hours, in the month of June ; during which time the fermentation was ftrongeft in the bran and water, next in the plain water, and weak- eft in the lye. Taken out and dried, the firft weighed 18 lb. I2| oz. and fo had loft lib. 4! oz. 5 the fecond weighed 17 lb. 1 1 oz. and fo had loft 1 lb. 4 oz. j the laft weighed 17 lb. 12 oz. and fo had loft 1 lb. 7 oz. The bran and water, in this laft experiment, appears to have had a better effect than the old lye ; and the plain wa- ter than either. This queftion, therefore, ftill remains undecided. The only method, however, is pointed out, and a multipli- city Sedt.IL ON BLEACHING. 45 city of experiments mull be tried, before we can determine what liquor is in general beft. After fteeping, the cloth is carried to the putftock-mill, to be freed of all its loofe foulnefs. There can be nothing contrived fo effectual to anfwer the purpofe as this mill. Its motion is eafy, regular, and fafe. While it preffes gently, it turns the cloth ; which is continually wafhed with a ftream of water. Care muft be taken that no wa- ter be detained in the folds of the linen, otherwife that part may be damaged. SECT. IL Bucking and boiling. t I *His is the mod important operation 1 of the whole procefs, and deferves a thorough examination. Its defign is to loofen, and carry off, by the help of alka- line lixives or lyes, that particular fubftance in cloth, which is the caufe of its brown colour. 46 EXPERIMENTS PartIL colour. The falts, or afhes, as the bleach- ers call them, ufed in the compofition of the lye, demand, for many reafons, a parti- cular fcrutiny; and therefore I ftiall ex- amine them afterwards by themfelves. These afhes,. the pearl excepted, ought to be well pounded, before they are put i&to the copper for the Marcoft and Cajhub are very hard, and with fome difficulty yield their falts. As thefe two laft contain a very confiderable proportion of a real ful- phureous matter, which mull in fome de- gree tinge white cloth ; and as this is dif- folved much more by boiling, than by the inferior degrees of heat, while the falts may be as well extra£led by the latter, I would propofe that the water fhould never be brought to boil, and fhould be conti- nued for fome time longer under that de- gree of heat. The pearl afhes fhould ne- ver be put in till near the end, as they are eafily diffolved in water. If the falts were always of an equal ftrength, the fame quantities would make a 5ed.IL ON BLEACHING. 47 a lye equally ftrong: but they are not. Salts of the fame name differ very much from one another. The Mufcovy afhes are turning weaker every day, as every bleach- er muft have obferved, till at laft they turn quite effete. A decoddon from them, when new, muft differ very much from one when they have been long kept. Hence a neceffity of fome exa6t criterion to dif- cover when lyes are of an equal ftrength. The tafte cannot ferve, as that is fo vari- able, cannot be defcribed to another, and is blunted by repeated trials. The proof- ball will ferve the purpofe of the bleach- field fufficiently 5 and, by difcovering the fpecific gravity, will ihow the quantity of alkaline falts diffolved. But it cannot fhow the dangerous qualities of thefe falts ; for the lefs cauftic and lefs heavy this liquor is, the more dangerous and corrofive it may be for the cloth. This muft appear a paradox at prefent, but will afterwards be proved by many ex- periments. The third lye, which they draw from thefe materials by an infulion of 48 EXPERIMENTS Part II. of cold water, where I could plainly tafte the lime, appears to me more dangerous than the firft. The fecond lye, which they extract from the fame afhes, and which is reckoned about a third in ftrength, when compared to the firft, muft be of the fame nature ; nor do I think it fhould be ufed without an addition of pearl a£hes, which will correct it. It is taken for a general rule, That the folution of any body in its menftruum is e- qually diffufed through the whole liquor. The bleachers depending on this, ufe e- qual quantities of the top and bottom of their lye, when once clear and fettled ; taking it for granted, that there is an equal quan-* tity of falts in equal quantities of the lye. But if there is not, the mifiake may be of fatal confequence ; as the lye may be in fome places ftronger than what the cloth can with fafety bear. That general law of folution muft have taken its rife from par- ticular experiments, and not from reafon- ing. Whether a fufficient number of ex«> periments have been tried to afcertain this point, Se6l.II. ON BLEACHING. 4$ point, and to eftablifh an undoubted ge- neral rule, may be called in queftion. But when I had difcovered that lime makes part of the diflblved fubftance, and reflected how long its groffer parts will continue fufpended in water, * there appear- ed fironger reafons for my fufpe&ing that this rule, though it may be pretty general, does not take place here ; at leaft it is worth the purfuit of experiment. Exp. 4. I weighed at the bleachfield a piece of glafs in fome cold lye, after it had been boiled, ftood for two days, and about the fourth part of it had been ufed. The glafs weighed 3 drachms i~ grains in the lye, and 3 drachms y~ grains in river- water. The fame glafs weighed in the fame lye, when almoft all ufed, 2 grains lefs than? it had done before. This fhows, that the laft of the lye contained a third more of the dif~ folved body ; and, confequently, was a third ftronger than the firft of the lye. As this might, perhaps, be owing to a G continuation 5 o EXPERIMENTS PartIL continuation of the folution of the falts, I repeated the experiment in a different way, Exp. 5. I took from the furface fome of the lye, after the falts were diffolved, and the liquor was become clear. At the fame time I immerfed a bottle, fixed to a long flick, fo near the bottom, as not to raife the afhes there, and, by pulling out the cork by a firing, filled the bottle full of the lye near the bottom. The glafs weigh- ed in river- water 3 drachms 384 grains; in the lye taken from the furface 3 drachms 34-5- grains 5 and in the lye taken from the bottom 3 drachms 314 grains. This ex- periment fhows, that the lye at the bot- tom was, in this cafe, \ ftronger than the lye at the furface, At other times when I tried the fame experiment, I found no difference in the fpecific gravity ; and, therefore, I leave it as a queflion yet doubtful, though defer- ving to be afcertained by thofe who have an opportunity of doing it. As the lye frauds continually on the afhes, there can be Sedl.IL ON BLEACHING. 51 be no doubt but what is ufed laft muft be ftronger than the firft. I would, therefore, recommend, to general pradtice, the me- thod ufed by Mr "John Chrijiie y who draws off the lye, after it has fettled, into a fecond receptacle, and leaves the allies behind. By this means it never can turn ftronger ; and he has it in his power to mix the top and bottom, which cannot be done fo long as it ftands on the aflies. Having confidered the lye, let us next inquire how it adts. On this inquiry depends almoft the whole theory of bleach- ing, as its adtion on cloth is, at leaft in this country, abfolutely neceffary. We fhall fee, in fome experiments which follow on the natural effedts of thefe afhes, that one effedt they have on cloth, is the diminifh- ing of its weight ; and that their whitening power is, generally, in proportion to their weakening power. Hence arifes a proba- bility, that thefe lyes adt by removing fome- what from the cloth, and that the lofs of this fubftance is the caufe of whitenefs. This appears yet plainer, when the buck- G 2 ing, 52 EXPERIMENTS PartIL ing, which lafts from Saturday night to Monday morning, is attended to. There I have feen evident figns of a folution going on from the quantity of air-bubbles arifing, when the liquor was almoft cold. There are various and different opi- nions with regard to the operation of thefe falts : That they a£t by altering the exter- nal texture of the cloth, or by feparating the mucilaginous parts from the reft, or by extra&ing the oil which is laid up in the cells of the plant. The laft is the ge- neral opinion, or rather conjecture, for none of them deferves any better name ; but we may venture to affirm, that it is fo without any better title to pre-eminence, than what the others have. Alkaline falts diflolve oils, therefore thefe falts diffolve the cellular oil of the cloth, is all the foundation which this theory has to reft on ; too flight, when unfupported by experi- ment, to be relied on. In fettling this queftion, we fhall not only fix the theory of bleaching, but like- wife Seft.IL ON BLEACHING. 53 wife that of the lithontriptic quality of medicines, whofe effects on the human calculus are obferved to be the fame as the effedts of thefe materials on cloth. The folvents of the ftone, and the bleaching materials, are the fame. They produce fi- milar effects on both ; fuch as diminution of weight, a white colour, the generation of much elaftic air, and at laft a diffolution or feparation of parts. But their method of ading has not yet been afcertained by any certain and conclufive experiment. Let us then bring the queftion, if we can, to that teft. Wax is whitened by being expofed to the influence of the fun, air, and moifture. A difcovery of the changes made on it by bleaching, may throw a light upon the que- ftion. Exp. 6. Six drachms of wax were fliced down, expofed on a fouth window, Sep- tember 10. and watered. That day being clear and warm, bleached the wax more than all the following. It feemed to me to whiten 54 EXPERIMENTS Partll. whiten quicker when it had no water thrown on it, than when it had. Sept. 15. it was very white, and 1 drachm 3 grains lighter. 3! drachms of this bleached wax, and as much of unbleached, taken from the fame piece, were made into two candles of the fame length and thicknefs, having cotton wicks of the fame kind. The bleached candle burned one hour thirty- three minutes ; the unbleached three mi- nutes longer. The former run down four times, the latter never. The former had an obfcure light and dull flame 5 the latter had a clear pleafant one, of a blue colour at the bottom. The former when burning feem- ed to have its wick thicker, and its flame nearer the wax, than the latter. The former was brittle, the latter not. It plain- ly appears from thefe fa£ts, that the un- bleached wax was more inflammable than the bleached ; and that the latter had loft fo much of an inflammable fubftance, as it had loft in weight ; and confequently the fub- ftance loft in bleaching of wax is the oily part. Dr Hales obferves, that wax in di- ftillation affords an inflammable vapour. As Sed.IL ON BLEACHING. 55 As I had not an opportunity of repeating the former experiment, I do not look oa it as entirely conclufive ; for it is poffible that fome of the duft, flying about in the air, might have mixed with the bleached wax, and fo have rendered it lefs inflam- mable. Nor do I think the analogical reafoning from wax to linen without ob- jections. Let us try then if we cannot procure the fubftance extracted from the cloth, fhow it to the eye, and examine its different properties. The proper place to find it, is in a lye already ufed, and fully impregnated with thefe colouring particles. Exp. 7. I got in the bleachfield fome lye, v/hich had been ufed all that day for boiling coarfe linen, which was tolerably white, and had been twice boiled before. There could be no dreffing remaining in thefe webs. No foap had ever touched that parcel ; nor do they mix foap with the lye ufed for coarfe cloth. Some of this impregnated lye was evaporated, and left a dark-coloured matter behind. This fub- ftance felt oily betwixt the fingers, but would 56 EXPERIMENTS PartlL would not lather in water as foap does. It deflagrated with nitre in fuiion, and af- forded a tincture to ipirit of wine. By this experiment the falts feem to have an oily inflammable fubftance joined with them. Could we feparate this colouring fub- ftance from thefe falts, and exhibit it by itfelf, fo that it might become the obje£t of ex- periment, the queftion would be foon de- cided. Here chymiftry lends us its aflift- ance. Whatever has a ftronger affinity or attraction to the falts with which it is join- ed, than this fubftance has, muft fet it at liberty, and make it vifible. Acids at trad: alkaline fait from all other bodies ; and therefore will ferve our purpofe. Exp. 8. Into a quantity of the impreg- nated lye mentioned in the former experi- ment, I poured in oil of vitriol. Some bub- bles of air arofe, an inteftine motion was to be perceived, and the liquor changed its co- lour from a dark to a turbid white. It curd- led like a folution of foap, and a fcum foon gathered on the furface, about half an inch x m Sedt.II. ON BLEACHING. 57 in thicknefs, the deepnefs of the liquor not being above fix inches. What was below was now pretty clear. A great deal of the fame matter lay in the bottom ; and I ob- ferved, that the fubftance on the furface was precipitated, and fhowed itfelf heavier than water, when the particles of air, attached to it in great plenty, were difpelled by heat. This fubftance was in colour darker than the cloth which had been boiled in it. I procured a conftderable quantity of it by fkimming it off. When I tried to mix it with water, it always fell to the bottom. When dried by the air, it diminifhed very much in its fize, and turned as black as a coal. In this ftate it deflagrated ftrongly with nitre in fufion 5 gave a ftrong tincture to fpirit of wine ; and when put on a red- hot iron, burnt very llowly, as if it contain- ed a heavy ponderous oil ; and left fome earth behind. From the inflammability of this fub- ftance, its rejecting of water, and diflblving in fpirit of wine, we difcover its oleaginous na- H ture ; 58 EXPERIMENTS PartIL ture ; but from its great fpecific gravity we fee, that it differs very much from the ex- preffed or cellular oil of vegetables ; and yet more from their mucilage. That it diffolves in fpirit of wine, is not a certain argument of its differing from expreffed oils •> becaufe thefe, when joined to alkaline falts, and recovered again by acids, be- come foluble in fpirit of wine. The quanti- ty of earthy powder left behind after burn- ing, fhows that it contains many of the fo- lid particles of the flax. The fubftance extracted from cloth by alkaline lyes ap- pears then to be a compofition of a heavy oil, and the folid earthy particles of the flax. Whether this heavy oil differs origi- nally in the plant, from the oil expreffed from its cells, or whether the latter is con- verted into the former, by lofing in folu- tion great part of its air, I cannot deter- mine ; nor is it neceffary. At prefent they feem widely different. In what manner thefe falts adt fo as to diffolve the oils, and detach the folid par- ticles, whether from a certain polarity, as Dr Sea. II. ON BLEACHING. 59 Dr Hales imagines, or from other caufes, of which the imagination can fuggeft many, is not allowed us certainly to know. The fpeculation is too fubtile to admit of expe- riments, and too uncertain to be trufted to without thefe. It is enough for us to know on what principles in the cloth thefe falts operate. We fee evidently how much cloth muft be weakened by an impro- per ufe of thefe falts, as we find the folid particles themfelves are feparated. It is necelfary that cloth fhould be dry before bucking, that the falts may enter into the body of the cloth along with the water ; for they will not enter in fuch quantity, if it be wet ; and by afting too powerfully on the external threads, may endanger them. The degree of heat is a very material circumftance in this operation. As the ac- tion of the falts is always in proportion to the heat, it would appear more proper to begin with a boiling heat, by which a great deal of time and labour might be faved. H 2 The 60 EXPERIMENTS Part II. The reafon why this method is not follow- ed, appears to be this, j If any vegetable or vegetable fubftance is to be foftened, and to have its juices extracted, it is found more proper to give it gentle degrees of heat at firft, and to advance gradually, than to plunge it all at once in boiling wa- ter. This laft degree of heat is fo ftrong, that when applied at once to a vegetable, it hardens, inftead of foftening its texture. Dried vegetables are immediately put into boiling water by cooks, that thefe fub- ftances may preferve their green colour, which is only to be done by hindering them from turning too foft. Boiling water has the fame efFedt on animal fubftances ; for if fait beef is put into it, the water is kept from getting at the falts, from the outfide of the beef being hardened. But when we confider, how much of an oily fubftance there is in the cloth, e- fpecially at firft, which will for fome time keep off the water, and how the twifting of the threads, and clofenefs of the texture, hinders the water from penetrating, we (hall Sed.II. ON BLEACHING. 6r fliall find, that if boiling water were put on it at once, the cloth might be liable, in feveral parts, to a dry heat, which would be much worfe than a wet one. That the lyes have not accefs to all parts of the cloth, at firft, appears plainly from this, That when it has lain, after the firft bucking, till all the lyes are wafhed out, it is as black, in fome parts, as when it was fteep- ed. This muft be owing to the difcharge of the colouring particles from thofe places to which the lye has accefs, and to their remaining where it has not. It would feem advifeable, then, in the firft bucking or two, when the cloth is foul, to ufe the lye confiderably below the boiling point ; that by this foaking, or maceration, the foulnefs may be entirely difcharged, and the cloth quite opened for the fpeedy re- ception of the boilipg lye in the buckings which follow. The lyes fhould likewife be weakeft in the firft buckings, becaufe then they a£t only on the more external parts ; whereas, when the cloth is more opened, and the field 62 EXPERIMENTS PartIL field of adlion is increafed, the adlive powers ought to be fo too. For this rea-< fon they are at the ftrongeft after fome fourings. I was of opinion, that the cloth was al- lowed to lie too fhort time in the lye, and that more time on this account was confumed in the bleaching of cloth than was neceffary. What confirmed my fu- fpicions, was, that I obferved the cloth, which lay in the bucking-vat from Satur- day night to Monday morning, come out of a deeper colour, and when expofed to the air, became whiter, than the others of the fame parcel, which had been in the lye for twelve hours only. I caufed the experiment to be tried on a whole par- cel every time they were bucked ; and they advanced fafter, and with as great fafety, as other pieces which were managed in the common way. As to the effedt of foap mixed with the lye, I (hall have occafion afterwards to fhow, that it has no power in correcting the dangerous qualities of the lye. Scan. ON BLEACHING. 63 lye. At the fame time we fhall difcover, what is the proper corre&or. The only thing that now remains to be confidered, is, the management of the coarfe cloth, where boiling is fubftituted in place of bucking. This fpecies of linen cannot afford the time and labour neceffary for the latter operation ; and therefore they mull undergo a fhorter, and more aftive method. As the heat continues longer at the degree of boiling, the lyes ufed to the coarfe cloth muft be weaker than thofe it- fed to the fine. There is not fo much dan- ger from heat in the coarfe, as in the fine cloth, becaufe the former is of a more o- pen texture, and will allow the lye to pe- netrate more fpeedily. In the clofer kinds, however, I would advife, that the firft ap- plication of the falts fhould be made with- out a boiling heat. I cannot help greatly condemning the method generally ufed, of boiling all the cloth of that day in the fame lye. , I can fee no certainty of having all the lyes of the fame 64 EXPERIMENTS PartIL fame ftrength, becaufe neither the tafte nor proof-ball can be of ufe here j the tafte, becaufe the oily matter fheathes the falts ; the proof-ball, becaufe there is another fubftance here befides falts. But I am fure of this, that fo much filth, as a former experiment fhowed in lye often u- fed, cannot but communicate fome of it- felf to the cloth, and inftead of advancing, retard its whitenefs. It will appear after- wards, from experiments, that cloth boiled in a foul lye becomes heavier, and confe- quently takes in part of its foulnefs. If it is done for cheapnefs, I am not of opinion, that it will turn out fo on a further exami- nation ; for the laft additions of frefh lye muft be blunted greatly by the foulnefs in the old lye ; and the bleachers themfelves obferve, that they have not fuch a ftrortg effedt as the firft. No lye, therefore, can with any advantage be ufed above twice. SECT. Se6t. III. ON BLEACHING. 65 SECT. III. Alternate watering and drying. AFter the cloth has been bucked, it is carried out to the field, and fre- quently watered for the firft fix hours. For if, during that time, when it is ftrongly impregnated with falts, it is allowed to dry, the falts approaching clofer together, and, aflifted by a greater degree of heat, increa- fing always in proportion to the drinefs of the cloth, a£t with greater force, and de- ft roy its very texture. After this time, dry fpots are allowed to appear before it gets any water. In this ftate I imagine it pro- fits moft, as the latter part of the evapora- tion comes from the more internal parts of the cloth, and will carry away moft from thofe parts. The bleaching of the wax, in a preceding experiment, helps to con- vince me of this ; for it feemed to whiten moft when the laft particles of water were going off. T This 66 EXPERIMENTS Part it This continual evaporation from the fur- face of the cloth fhows, that the defign of the operation is to carry off fomewhat remaining after the former procefs of buck- ing. This appears likewife from a fadt known to all bleachers, that the upper fide of cloth, where the evaporation is ftrong- eft, attains to a greater degree of white- nefs than the under fide. But it is placed beyond all doubt by the experiment in fe£t. i. of part 4.; where it appears, that cloth turns much lighter by being expofed to the influence of the fun, air, and winds, even though the falts have been wafhed out of it. What, then, is this fubftance ? As we have difcovered in the former feftion, that the whitening, in the operation of bucking > depends on the extracting or loofening the heavy oil, and folid particles of the flax 5 it appears highly probable, that the effects of watering, and expofition to the fun, air> and winds, are produced by the evapora- tion of the fame fubftance, joined to the falts, with which compofite body the cloth Sedt.HL ON BLEACHING. 67 is impregnated when expofed on the field. That thefe falts are in a great meafure car- ried off or deftroyed, appears from the cloth's being allowed to dry without any danger, after the evaporation has gone on for fome time. If we can fhow, that oils and falts, when joined together, are capable of being exhaled, in this manner, by the heat of the atmofphere, we fhall reduce this queftion to a very great degree of cer- tainty. Exp. 9. Sept. 10. I expofed, in a fouth- weft window, half an oz. of Cajlile foap, fliced down, and watered. Sept. 14. when well dried, it weighed but 3 dr. 6 gr. Sept. 22. it weighed 2 dr. 2 gr. Sept. 24. it w r eighed 1 dr. 50 gr. It then feemed a very little whiter > but was much more mucilaginous in its tafte, and had no de- gree of faltnefs, which it had before. It appears, from this experiment, that foap is fo volatile, when watered, and expo- fed to air not very warm, that it lofes gbove the half of its weight in fourteen days. I 2 The 68 EXPERIMENTS Part II, The fame muft happen to the faponaceous fubftance, formed from the conjun&ion of the alkaline falts, heavy oil, and earthy particles of the flax. The whole defign, then, of this operation, which, by way of pre-eminence, gets the name of bleaching, is to carry off, by the evaporation of water, whatever has been loofened by the former procefs of bucking. Against this dodrine there may be brought two objections, feemingly of great weight. It is a general opinion amongft bleachers, that linen whitens quicker in March and April, than in any other months : but as the evaporation cannot be fo great at that time, as when the fun has a greater heat ; hence the whitening of cloth is not in proportion to the degree of evaporation ; and therefore the former cannot be owing to the latter. This objection vanifhes, when we confider, that the cloth which comes firft into the bleachfield, in the fpring, is clofely attended, having no other to interfere with it, for fome time j and, s it is the whiteft, gets, in the after buck- ings, Sea. III. ON BLEACHING. 69 ings, the firft of the lye; while the fe- cond parcel is often bucked with what has been ufed to the firft. Were the fadt true, on which the objection is founded, this would be a fufficient anfwer to the ob- jection. But it appears not to be true, from an obfervation of Mr 'John Chryjlie, That cloth laid down in the beginning of June y and finifhed in September takes ge- nerally lefs work, and undergoes fewer o~ perations, than what is laid down in March> and finifhed in June. The other obje&ion is, That cloth dries much fafter in windy weather than in calm funfhine ; but it does not bleach fo faft. This would feem to fhow, that the fun has fome particular influence independent on evaporation. In anfwer to this objection, let it be confidered, that it is not the eva- poration from the furface, but from the more internal parts, as I faid before, that is of benefit to the cloth. Now, this latter evaporation muffc be much ftronger in fun- fhine than in windy weather, on account ■of the heat of the fun, which will make the 7 o EXPERIMENTS Partll, the cloth more open ; while the coldnefs of windy weather muft fhut it up, fo that the evaporation will all be from the fur- face. Clear funfhine, with a very little wind, is obferved to be the beft weather for bleaching ; a convincing proof that this reafoning is juft. It would feem to follow as a corollary from this reafoning, that the number of waterings fhould, in general, be in proporr- tion to the ftrength of the lye j for the ftronger the lye is, the more there is to be evaporated $ and the greater the danger, in cafe the cloth fhould be allowed to dry. But there is an exception to this general rule, arifing from the conlideration of an- other circumftance. It is obferved, that cloth, when brown, dries fooner, than when it becomes whiter, arifing from the clofenefs and oilinefs, which it then has, not allowing the water a free paffage. Per- haps that colour may retain a greater degree of heat, and in that way affift a very little. Cloth, therefore, after the firft buckings, muft Sed.IIL ON BLEACHING. ft muft be more carefully watered than after the laft. It follows likewife from this reafoning, that the foil of the bleachfield Ihould be gravelly or fandy, that the water may pafs quickly through it, and that the heat may be increafed by the reflection of the foil : for the fuccefs of this operation depends on the mutual adlion of heat and evaporation. It is likewife neceifary that the water fhould be light, foft, and free from mud or dirt, which, not being able to rife along with the water, mull remain behind. When there is much of this, it becomes neceifary to rinfe the cloth in water, and then give it a milling, to take out the dirt • elfe it would be fixed in the cloth by the following buck- ing, as it is not foluble by the lye. This operation has more attributed to it by bleachers than it can juftly claim. The cloth appears, even to the eye, to whiten under thefe alternate waterings and dry- ings ; and thefe, naturally, get the honour of it, when it more properly belongs to the former 72 EXPERIMENTS PartlL former operation. Here lies the fallacy. Alkaline falts give a very high colour to the deco&ions, or infufions of vegetables. This is probably owing to the folution of the oleaginous colouring particles of the plant which particles, being opened and feparated by the falts, occupy a greater fpace, and give a deep colour to the liquor. The cloth participates of the liquor and colour. Hence bleachers always judge of the good- nefs of the bucking by the deepnefs of its colour. The rule, in general, is good. I obferve, that in thofe buckings which con- tinue from the Saturday night to the Mon- day morning, the cloth has always the deepeft colour. When that cloth has been expofed fome hours to the influence of the air, thefe colouring particles, which are but loofely attached to it, are evaporated, and the linen appears of a brighter colour. This operation does no more than complete what the former had almoft finished. If its own merit were thoroughly known, there would be no occalion to attribute that of another operation to it. Thread, and open cloths, fuch as diaper, may be redu- ced Se&IIL- ON BLEACHING. 73 ced to a great degree of whitenefs, after one bucking, by it alone. No cloth, as would appear, can attain to a bright white- nefs without it. Since the only advantage of watering is the removal of the falts, and what they have diffolved, might we not effedluate this by fome cheaper, and more certain method ? For it occupies many hands ; and mull depend, altogether, on the uncertain- ty of the weather - y fo that, in the begin- ning of the feafon, the bleacher is often obliged to repeat his buckings without bleaching. We might take out the alka- line falts by acids ; but then the other fub- ftance would be left alone in the cloth, nor would any wafhing be able to remove it. Mill-wafhing appears a more probable me- thod of taking out both falts and oils y and it would feem that this might, in a great meafure, fupply the place of watering ; but upon trial it does not fucceed. Two parcels of linen were managed equally in every o~ ther refpe£t, except in this, That one was watered, and expofed to the influence of the K air 5 74 EXPERIMENTS PartIL air, and the other was only mill-wafhed. This method was followed until they were fit for fouring. The cloth which had been mill-wafhed, had a remarkable green co- lour, and did not recover the bright colour of the pieces managed in the common way, until it had been treated like them for a fortnight. The green colour was certainly owing to a precipitation of the fulphureous particles, with which the lye is impregnated, upon the furface of the cloth ; owing to the falts being wafhed off more fpeedily than the fulphur, to which they are united in the lye. The attachment betwixt thefe two bodies, we know, is very loofe, and the feparation eafilymade. Evaporation, then, alone is fuf- ficient to carry off thefe fulphureous particles. SECT. IV. Souring. TT is well known to all chymifts, and 3 will afterwards appear, that alkaline falts are convertible, by different methods, into abforbent earths. Frequent folution in water* Se6t.IV. ON BLEACHING. 75 water, and evaporation of it again, is one of thefe. This tranfmutation, then, of thefe falts, which are not volatilifed, or wafhed away, muft be continually going on in the cloth under thefe alternate waterings and dryings of the former procefs. Not much, indeed, after the firft two or three buckings; becaufe the falts, not having entered deep into the cloth, are eafily wafhed off, or e- vaporated. But when they penetrate into the very compofition of the laft and minu- ted fibres, of which the firft veflels are made, they find greater difficulty of efca- ping again, and muft be more fubjedt to this tranfmutation. But if we confider the bleaching afhes as a compofition of lime and alkaline falts, we muft difcover a frefh fund for the depofition of this abforbent earth. The common cauftic, a compofi- tion of this very kind, foon converts itfelf, if expofed to the open air, into a harmlefs earthy powder. Frequent buckings and bleachings load the cloth with this fubftance. It becomes, then, neceffary to take it out. No wafii- K 2 ing 76 EXPERIMENTS Partll. ine can do that, becaufe earth is not foluble in water. Nothing but acids can remove it. Thefe are attracted by the abforbent earth, join themfelves to it, and compofe a kind of neutral imperfect fait, which is fo- luble in water ; and therefore eafily wafhed out of the cloth. The acid liquors common- ly ufed are butter milk, which is reckoned the beft; four milk , infulions of bran, rye-meal, &c. kept for fome days till they four. Sour whey is thought to give the cloth a yellow colour. The linen ought to be dried before it is. put in the four, that the acid particles may penetrate, along with the watery, thro' the whole. A few hours after it has been there, air-bubbles arife, the liquor fwells, and a thick fcum is formed ; manifeft figns of a fermentation. The following ex- periment fhows the degree of heat which attends it. Exp. 10. May 25. I put a thermometer of Fahrenheit's into fome butter milk of which the bleachers were compofing their fours, and Sea. IV. ON BLEACHING. 77 and which ffcood in a vat adjoining to ano- ther, where the milk was the fame, and the fouring procefs had been going on for two days. After the thermometer had been twenty minutes in the butter milk, the mercury ftood at 64 degrees. In the fouring vat it rofe to 68 degrees. An in- creafe of 4 degrees fhows a pretty brifk in- teftine motion. To what are all thefe effects owing ? To the acetous fermentation going on in thofe vegetable liquors, whofe acids, extricating themfelves, produce heat, inteiline motion, and air-bubbles. As the change is flow, the procefs takes five or fix days before it is finilhed. During this time the acid par- ticles are continually uniting themfelves to the abforbent earth in the cloth. That this fermentation goes on in the liquor a- lone, appears from this confideration, that the fame effects, to. air-bubbles, and fcum, are to be feen in the butter milk a~ lone. The only effect, then, it has, fo far as I can fee, is, by the fmall degree of heat, and inteftine motion, which attend it; 7 8 EXPERIMENTS PartIL it, to affift the junction of the acid and ab- forbent particles. We (hall prefently fee, that this procefs may be carried on, to as great advantage, without any fermentation; and therefore it appears not abfolutely ne- celfary. When thefe abforbent particles are fully faturated, the remaining acids may unite with, and have fome fmall effedt in extract- ing the colouring particles. This appears from the two following experiments, Exp. ii. Sept. 20. A piece of cloth which had been fteeped, weighing 41- gr. was put into a half-pound of butter milk, whigged, and well foured, by a mixture of water, and by boiling. Sept. 24. when tal^en out, and waihed in water, it appeared a very little whiter. The mineral acids, as will appear afterwards, whiten cloth, even though they are very much diluted. Just before the acetous fermentation is finished, the cloth fhould be taken out ; o- therwife the fcum will fall down, and lodge in Sea. IV. ON BLEACHING. 79 in the cloth, and the putrefaction, which then begins, will weaken it. This appears from the following experiment. Exp. 12. Sept. 16. A piece of cloth weighing 42 gr. was laid in butter milk un- whigged. Nov. 15. the milk had a putrified fmell. The cloth was a little whiter, but very tender ; and weighed, when well wash- ed in warm water, and dried, 40 gr. All the fours made of bran, rye-meal 7 &c. ought to be prepared before ufe ; for by this means fo much time will be faved. Befides, when the water is poured upon the cloth, and bran, as is done in the manage- ment of coarfe cloth, the linen is not in a better fituation than if it had been taken up wet from the field ; and by this means the acid particles cannot penetrate fo deep. A- gain, this method of mixing the bran with the cloth, may be attended with yet worfe confequences. All vegetable fubftances, when much prefied, fall into the putrefcent, and not the acetous fermentation. This rnuft, and does happen to the bran prelfed betwixt 8o EXPERIMENTS PartIL betwixt the different layers of the linen. I had occafion to fee it one day, in a bleach- field, when they were drawing a parcel of coarfe cloth foured in this manner. The bran had attained to a confiderable degree of putrefaction, but the liquor had not. The cloth, immediately above and below this putrid bran, mult have been weakened by it. For thefe obvious reafons I would propofe, that all the fours fhould be prepa- red before the cloth is fteeped in them ; and that none of the bran, or meal, fhould be mixed with the cloth. The fours are ufed ftrongeft at firft, and gradually weakened till the cloth has attain- ed to its whitenefs. In the firft fourings, there is more of the earthy matter in the cloth, from the many buckings it has un- dergone, than what there can be after- wards. As the quantity of this matter de- creafes, fo Aould the ftrength of the four. I am not, however, of opinion, that there is the leaf!; danger at any time, from too ftrong a four. Why they £hould not be ufed fome- what Sea.IV. ON BLEACHING. 8i what fooner than they are, I could never fee any reafon. What is moft wanted in this operation, is, a more expeditious and cheaper method of obtaining the fame end. As it takes five or fix days, it retards the whitening of the cloth confiderably ; and as bleachers are obliged to fend for milk to a great diftance, it becomes very dear. This laft confidera- tion makes them keep it fo long, that, when ufed, it can have no good effect 5 per- haps it may have a bad. There is one confederation that may lead us to fliorten the time. It is obferved, that the fouring procefs is fooner finished in warm than in cold weather. Heat quickens the fermentation, by aiding the intefcine motion. I Would propofe, then, that the vats fliould not be buried in the ground, as they always are, which muft keep them cold ; and that there fliould be pipes along the walls of the room, to give it that degree of heat, which, on trial, may be found to aniwer heft. I am of opinion, that there L are 82 EXPERIMENTS Part III are few days in fummer fo hot as is necef- fary \ and that the beginning and end of the feafon, is by very much too cold. That this is no ideal fcheme, the following fadt i^ a fufficient proof. There are two vats in Salton bleachfield, adjoining to a partition- wall, at the back of which there is a kit- chen-fire. In thefe vats the fouring procefs is finifhed in three days, whereas it lafts five or fix days in the others placed, round the fame room. This improvement, though it fhortens the time of fouring a very little, yet is no remedy againft the fcarcity and dearnefs of milk fours. Such a liquor as would ferve our purpofe, muft be found either among the vegetable acids, which have no further fermentation to undergo, or among the mi- neral acids. The former are a large clafs, and contain within themfelves many differ- ent fpeeies, fuch as the acid juice of feveral plants, vinegars made of fermented liquors, and acid falts called tartars. But there is one obje&ion againft all thefe vegetable a- cids : They all contain, along with the acid^ a Sea. IV. ON BLEACHING. 83 a great quantity of oleaginous particles, which would not fail to difcolour the cloth. Befides, the demand of the bleachfields would raife their price too high. The mineral acids have neither of thefe objections. They are exceedingly cheap, and contain no oil, though many chymifts have afferted that they did. I will freely own, that, at firft, I had no great opinion of their fuccefs 5 from two reafons ; their want of all fermentation, which I then looked on as neceflary ; and their extreme corrofivenefs. But the experience of two different fummers, in two different bleach- fields, has convinced me, that they will an- fwer all the purpofes of the milk and bran fours ; nay, in feveral refpedts, be much preferable to them. I have feen many pieces of fine cloth, which had no other fours, but thofe of vitriol, and were as white and ftrong as thofe bleached in the common way. I have cut feveral webs through the middle, and bleached one half with milk, and the other with vitriol, gave both the L 2 lame 84 EXPERIMENTS. Part II. fame number of operations, and the latter were as white and ftrong as the former. The method, in which it has been hi- therto ufed, is this. The proportion of the oil of vitriol to the water, with which it is diluted, is half an ounce, or at mofl three quarters of the former, to a gallon of the latter. As the milk fours are diminished in Strength, fo ought the vitriol fours. The whole quantity of the oil of vitriol to be ufed, may be firft mixed with a fmall quan- tity of water, then added to the whole quantity of water, and well mixed together. The water Should be milk- warm j by which means the acid particles will pene- trate further, and operate fooner. The cloth Should then be put dry into the liquor. It is obferved, that this four performs its talk much fooner than thofe of milk or bran ; fo that Mr John Chryflie, in making the trial, ufed to lay the milk fours twenty- four hours before the vitriol. I am of opi- nion, that five hours will do as much with this four, as five days with the common fort, Seft. IV. ON BLEACHING. 85 fort. But the cloth can receive no harm in allowing it to remain for fome days in the four, but rather, on the contrary, an ad- vantage, as we fhall have occafion after- wards to obferve. The cloth is then ta- ken out, well rinfed, and mill-wafhed in the ordinary way. The liquor, while the cloth lies in this four, is lefs acid the fecond day than the firft, lefs the third than the fecond, and fo diminifhes by degrees. At firft it is clear, but by degrees a mucilaginous fubftance is obferved to float in it, when put into a glafs. This foulnefs increafes every day. This fubftance extracted by the acid, is the fame with what is extracted by the alkaline falts ; and blunts the acidity of the former, as I have fhown it does the alkalefcency of the latter. This will appear more plain, when I come to fhow the natural effefts of thefe acid falts on unbleached cloth. Hence the liquor lofes, by degrees, its acidity. But as the acid falts do not unite fo equally with oleaginous fubftances, as the alkaline do, the liquor is not fo uniformly tinged in the 86 EXPERIMENTS Partll. the former, as in the latter cafe, and the >£>i! JL »ci 3I*v' j, ^ j i jo i Jonjiv to 3iJjr 3jnj. j if i it* m mucous fubftance prefents itfelf floating in it. It is obferved, that, in the firft fouring, which is the ftrongeft, the liquor, which was a pretty ftrong acid before the cloth was put in, immediately afterwards be- comes quite vapid ; a proof how very foon it performs its tafk. But in the following operations, as the linen advances in white- nefs, the acidity continues much longer ; fo that in the laft operations the liquor lofes very little of its acidity. This happens al- though the firft buckings, after the firft fourings, are increafed in ftrength, while the fours are diminifhed. There are two caufes to which this is owing. The tex- ture of the cloth is now fo opened, that al- though the lyes are ftrong, the alkaline falts and abforbent earth are eafily wafhed out ; and the oleaginous particles are, in a great meafure, removed, which help to blunt the acidity of the liquor. I have heard two objections brought gainft SedUV. ON BLEACHING. gainft the ufe of vitriol fours. One is, That the procels of fouring with milk is perform- ed by a fermentation j and as there is no fermentation in the vitriol fours, they can- not ferve our purpofe fo well : the other. That they may hurt the texture of the cloth. The anfwer to the former objection is very fhort, That the vitriol fours operate fuc- cefsfully without a fermentation, as expe- rience fhows ; and therefore in them a fermentation is not necelfary. The fame objection might be made to ftrike againft the vegetable fours, That as the mineral acids operate without fermentation, there- fore the vegetable, which ferment, will not fucceed 5 but the truth is, that both fuc- ceed. The vegetable liquors muft ferment* that their acids may be fet free ; but the mineral acids neither ftand in need, nor are capable of any fuch change. This fhows evidently, that all the advantage of fermentation is to difengage the acid falts, that they may exert themfelves on the cloth. As to the latter objedlion, That oil of vi- triol i 88 EXPERIMENTS Part 11, triol, being a very corrofive body, may hart the cloth ; that will vanifti likewife, when it is confidered how much the vitriol is diluted with water, that the liquor is not ftronger than vinegar, and that it may be fafely taken into the human body. But there will remain no doubt of its fafety, when I come afterwards to fhow, that I have kept linen in a ftrong four of vitriol for many months, and that the cloth was as ftrong after it was taken out, as when it was put in. Thefe experiments convinced me of its fafety, before I had experience of its ufe in the bleachfield. That it may be ufed with fafety, much ftronger than what is necefiary in the bleachfield, appears from the following ex- periment with regard to the ftamping of linen. After the linen is boiled in a lye of aihes, it is bleached for fome time. After this, in order to make it receive the colour, it is fteeped in a four of water and oil of vitriol, about fifteen times ftronger than that made ufe of in the bleachfield ; for to ioo gallons of water are added two and a half SedhV. ON BLEACHING- £9 half of oil of vitriol. Into this quantity of liquor, made fo warm as the hand can juft be held in it, is put feven pieces of 28 yards each. The linen remains in it about two hours, and comes out remarkably whiter. The fine cloth often undergoes this opera- tion twice. Nor is there any danger if the. oil of vitriol is well mixed with the wa- ter. But if the two are not well mixed to- gether, and the oil of vitriol remains, in fome parts, undiluted, the cloth is corro- ded into holes. Let us now take a view of the advan- tages which the vitriol fours muft have o« ver the milk. The latter is full of oleagi- nous particles, fome of which muft be left in the cloth : but the cafe is worfe if the fcum is allowed to precipitate upon the cloth. The former is liable to neither of thefe objections. The common fours haften very faft to corruption ; and if, from want of proper care, they ever arrive at that ftate, muft damage the cloth very much. As the milk M is go EXPERIMENTS Part XL is kept very long, it is often corrupted be- fore it is ufed ; and, without adting as a four, has all the bad effects of putrefaction. The vitriol fours are not fubjedt to putre- faction. The milk takes five days to perform its talk ; but the vitriol fours do it in as many hours ; nay, perhaps, in as many minutes. Their junction with the abforbent particles in the cloth muft be immediate, whenever thefe acid particles enter with the water. An unanfwerable proof that the fadt is fo, arifes from the circumftances which happen when the cloth is firft fteeped in the vitriol four y the cloth has no fooner imbibed the acid liquor than it lofes all acidity, and be- comes immediately vapid. This efFedt of vitriol fours mult be of great advantage in the bleachfield, as the bleachers are at prefent hindered from enjoying the feafon by the tedioufnefs of the fouring procefs. The whole round of operations requires fe- ven days ; to anfwer which they mull have feven parcels, which are often mixing to- gether, and caufing miftakes. As three days> Seft. IV. ON BLEACHING. 91 days, at moft, will be fufficient for all the operations when vitriol fours are ufed, there will be no more than three parcels. The clo :h will be kept a fhorter time in the bleachfield, and fo arrive fooner at market. The milk fours are very dear, and often difficult to be got ; but the vitriol are cheap, may be eafily procured, and at any time. There is yet another advantage in the ufe of vitriol, and that is its power of whitening cloth. It will appear, after- wards, by experiments, that, even in this diluted ftate, its whitening power is very confiderable. We have already feen, that it removes the fame colouring particles, which the alkaline lyes do. What of it then remains, after the alkaline and abforbent particles are neutralized in the cloth, muft a£t on thefe colouring particles, and help to whiten the cloth. That this is really the cafe, appears from the following fad:. Mr Chryjlie being obliged to chufe twenty of the whiteft pieces out of a hundred, five M 2 of 92 EXPERIMENTS PartH. of the twenty were taken out of fe- ven pieces which were bleached with vi- triol. t From both experience and reafon, I muft then give it as my opinion, That it would be for the advantage of our linen manufa&ure, to ufe vitriol in place of milk fours. SECT. V. Hand-rubbing with foap and warm water > rubbing-boards^ Jlarcbing, and bluing. AFter the cloth comes from the four- ing, it fhould be well wafhed in the wafhing-mill, to take off all the acid pan- tides which adhere to its furface. All acids difcompofe foap, by feparating the al- kaline falts and oily parts from one another. Were this to happen on the furface of the cloth, the oil would remain ; nor would the wafhing-mill afterwards be able to carry it off. From Seft.V. ON BLEACHING. 93 From the wafhing-mill the fine cloth is carried to be rubbed by womens hands, with foap and water. As the liquors which are generally employed for fouring, are impregnated with oily particles, many of thefe muft lodge in the cloth, and re- main, notwithftanding the preceding mill- ing. It is probable, that all the heavy oils are not evaporated by bleaching. Hence it becomes neceflary to apply foap and warm water, which unite with, diffolve, and car- ry them off. It is obferved, that if the cloth, when it is pretty white, gets too much foap, the following bleaching is apt to make it yellow : on that account they often wring out the foap. I believe it would be proper to give it always a milling with warm water, before bucking, to take out the foap and loofened dirt more ef- fectually. The preceding fa£t is a ftrong argument in its favour. It is a matter worth inquiring into, whether hard or foft foap is beft for cloth. Moft bleachers, I think, agree, that hard foap is apt to leave a yellownefs in the cloth, 94 EXPERIMENTS PartIL cloth. I havS been told, that the ufe of hard foap is difcharged in Holland. As there muft be a confiderable quantity of fea- fait in this kind, which is not in the foft, and as this fait appears prejudicial to cloth, J would prefer the latter. The management of the coarfe cloth is very different, in this operation, from the fine. Inftead of being rubbed with hands, which would be too expenfive, it is laid on a table, run over with foap, and then put be- twixt the rubbing-boards, which have rid- ges and grooves from one fide to another, like teeth. Thefe boards have fmall ledges to keep in the foap and water, which faves the cloth. They are moved by hands, or a water-wheel, which is more equal, and cheaper. The cloth is drawn, by degrees, through the boards, by men who attend ; or, which is more equal, and cheaper, the fame water-wheel moves two rollers, with ridge and groove, fo that the former enters the latter ; and, by a gentle motion round their own axis, pull the cloth gradually through the boards. This Sedt.V. ON BLEACHING. 95 This mill was invented in Ireland about thirty years ago. The Irijh bleachers ufe it for their fine, as well as coarfe cloth. How- ever neceflary it may be for the latter, on account of its low price, I fee no reafon, on that account, for ufing it to the former. Thefe rubbing-boards were difcharged, fome years ago, in Ireland^ by the Truftees for the manufactures of that country, con- vinced from long experience of their bad ef- fects. But as proper care was not taken to inftruCt the bleachers, by degrees, in a fa- fer method, they continued in the old, made a party, and kept poffeffion of the rubbing-boards. There were confiderable improvements made in them in this country ; fuch as the addition of the ledges, to keep the cloth moift ; and of the rollers, which pull the cloth more gradually than mens hands. Thefe improvements were firft made in Salt on bleachfield. The objections againft thefe rubbing- boards, I think, are unanfwerable. By rub- bing on fuch an unequal furface, the folid fi- brous part of the cloth is wore ; by which means 9 6 EXPERIMENTS Part II, means the cloth is much thinned, and, in a great meafure, weakened, before it corned to the market. As a proof of what I fay, if the water which comes from the cloth irk the rubbing-boards, is examined, it will be found full of cottony fibrous matter. Thefe boards give the cloth a cottony furface, fo that it does not keep long clean. Again, they flatten the threads, and take away all that roundnefs and firmnefs, which is the diilinguifhing property of cloth bleached in the Dutch method. For thefe reafons I am of opinion, that they are entirely prejudicial to fine cloth ; and hope they will not be employed in this country to it, as I know they flill are by many bleachers who follow the Irijh method. As they feem to be, in fome mea- fure, neceffary to render the expence of bleaching coarfe linen lefs, they ought ne- ver to be ufed above twice, cr thrice at moft. They might, I think, be rendered much more fafe, by lining their infides with fome foft elaftic fubftance, that will not wear the cloth fo much as the wooden teeth do, Sc into glafs. Exp. 23. Two fcruples of quick-lime were faturated with fpirit of fea fait, which pro- duced a yellow cailftic liquor, that burnt the tongue when applied to it. Being eva- porated, and kept in the kitchen-fire for two hours, I got a fubftance that fcarcely diflblved in water, nor in the leaft efFerve- fced with acids ; but turned fyrup of violets green, and tailed jufl like alkaline falts. It was put for an hour and a half in a reverbe- P ratory ii 4 EXPERIMENTS Partlll. ratory furnace, and I had 22 gr. of a gritty undiffolvable fubftance. Thus the acid has changed the calcarious bafe into an ear- thy fubftance, that is of a different nature from quick-lime. I purfued thefe trials further, to fee if I could fucceed better with the other mineral acids. Exp. 24. Chalk was faturated with fpi- rit of nitre, and then put into a kitchen-fire for half an hour. I got a fubftance which was undiffolvable in water, and to me ap- peared to be like chalk. Exp. 25. Quick-lime faturated with the fpirit of vitriol, afforded a bitter cau- ftic liquor, which excoriated my tongue. When evaporated, it was put into the kit- chen-fire for an hour. I got a brown fub- ftance, which was a little hot in the mouth, did not appear to be diffolvable in water, and afforded a lime-water. From thefe experiments it appears, that a Sed.IL ON BLEACHING. 115 a fubftance formed of an acid fait and ab- forbent earth, has fome of the properties of alkaline falts, while it wants others. The chymifts, for they generally follow Stahl in this opinion, have been led aftray by the cauftic tafte of the production. Notwith- ftanding the ill fuccefs of thefe experiments, to prove, that alkaline falts are a compound of an abforbent earth and an acid, yet I ftill think there is a great degree of probabir iity in that fide of the queftion, from the following reafons. Those plants which contain no acid, afford no alkaline fixed fait, fuch as onions, muftard, &c. If fuch plants as contain an acid, are diftilled, and the acid forced over with a ftrong fire, they afford lefs alkaline fait. Alkaline falts are made more alkaline by a ftronger heat than what was ufed be- fore ; which fhows, that more of the acid has been driven off by the fire. " Nitre, " without any addition, kept long in fu- " fion, acquires a cauftic alkaline nature There are fcarce any of the properties of * Junker de falib. alkal. fix, P 2 alkaline n6 EXPERIMENTS PartllL alkaline falts, but what belong either to the abforbent earths, or acids. To the former they owe their fixednefs in the fire, their at- traction and effervefcence with acids, with all the properties that depend on this caufe, and their power of turning the fyrup of vio- lets green : to the latter, their cauftic power, their folubility in water, their trans- parency when diflblved in it, their attrac- tion of moifture, their junction with oils, and their yitrefcency. If there are any par- ticles of fire added to, and fixed in the al- kaline falts, as it is probable there may be, thefe may a little vary fome of the proper- ties : As for inftance, alkaline falts attraCt a- cids with a greater force, than abforbent earths do, though the laft deftroy a greater quantity. This ftronger attraction in alkaline falts may be owing to their parts being more opened, than thofe of the earth, to the junction of fome particles of fire, or, per- haps, to the remaining acid particles, be- tween whom and the other acid there may be an attraction. This doCtrine will receive an additional ftrength, by confidering, out of what fubftance or fubftances, pre-exifting in Seft. II. ON BLEACHING. 117 in the plant, thofe alkaline falts are formed. The general opinion of chymifts, as I mentioned before, is, that they are formed by a, new combination of principles during combuftion, I imagine they are formed by a feparation. The eflential falts of plants feem to be the produdl of an acid, and an abforbent earth 5 for thefe two, as we have fhowed before, are fufficient to make a neu- tral fait. There is no fad, I think, more clearly proved, than that there are acid par- ticles continually circulating, in greater or lefs quantity, with the air. I have tried the allies of plants, and I find they contain a great quantity of abforbent particles. Hence, then, the effential falts of vege- tables. But thefe falts extracted, cryftal- lifed, and calcined by themfelves, afford, as Boerhaaroe informs us, an alkaline fait. Why not likewife when the vegetable is burnt ? This is the moft natural way of ac- counting for their origin, without flying to new combinations during combuftion. The fire will evaporate all the water, difpel the greateft part of the acid from thefe neu- tral u8 EXPERIMENTS Part in. tral faltsj and there will remain a fmall quantity of pure folid acid, joined to an ab- forbent earth *, with, perhaps, fome par- ticles of fire in the compofition. SECT. III. Mufcovy or blanch ajhes. f I ^HE bulk of mankind are led by JL names. That two fubftances enjoy the fame denomination, is enough, to the * Long after thefe papers were wrote, I difcovered the fame opinion, with regard to the compofition of alkaline falts, in the writings of a celebrated chymift, Homberg des principes de chymie en general, Memoires pour /' annee 1 702. Ces fels fixes lixi and are, like it, friable betwixt the fingers. The tongue, when applied, adheres to them. The firffc tafte which one perceives, is that of an alka- line fait ; but this goes foon away, and leaves a ftrong tafte of lime, which is pe- culiar to this fait. They never turn moifl in the air ; which plainly difcovers, that they contain little alkaline fait. Some fmall bits of charcoal are to be feen in their compofi- tion. Exp. 27. On the addition of the acid mixture to a drachm of Mufcovy afhes, there arofe an ebullition, which, though it was not i2o EXPERIMENTS PartHL not violent, yet continued long after the acid was joined to it. When they had got 4 fpoonfuls, I took out a little piece to break it y and to the tafte it feemed infipid, and gritty like a ftone. They confumed 17 tea- fpoonfuls. When the faturation was fully completed, it tafted bitter, and very differ- ent from the two former falts. Exp. 28. To feparate the falts from thefe afhes, I put half a pound in two pounds of water, and kept it pretty warm over the fire, but did not let it boil, for fear of dif- fipating the volatile parts, if there were any, till I thought the falts would be diffolved ; then I poured off the water. A half-pint was added to the remaining powder, which, after boiling fome minutes, was likewife poured off. It was treated twice more in the fame way. The laft that came off was .not fait, but had a tafte like lime-water. The deco&ion all together, when ftrained, was about three pints. Though carefully examined, it gave no fign of containing ful- phur. After all was ftrained, there remain- ed in the paper $\ dr. of a whitifh pow- der, SeailL ON BLEACHING. 121 der, which added to 2 oz. 5 dr. of undif- folvable fubftance, that lay at the bottom of the pot, when the water was poured off, made in all 3 oz. 5! dr. This decoc- tion boiled into half a pint, and fet for a fortnight in a cellar, gave no fign of any other fait. When all the water was eva- porated, I had 1 o dr. 15 gr. of a very cau- ftic fait, which feemed lighter than the falts of the blue and pearl afhes, and turn- ed very moift, when kept from the fire twenty-four hours. It appears that 3 oz. 18. gr. have been rendered volatile by the water, a greater quantity than in any of the two former falts. This lofs of fubftance probably a- rifes from the watery parts contained in thefe afhes. Exp. 29. To afcertain the ftrength of thefe falts, I diffolved half a drachm in water. The acid mixture produced a ftronger effervefcence than with the form- er falts ; and four and a half tea-fpoonfuls of it were required to faturate it. A Q_ brownifh 12* EXPERIMENTS PartHL brownifh powder fell to the bottom of the glafs in great quantity. Thefe falts, then, appear to be ftronger antacids than the former two, by their greater ebullition, and the greater quantity of acid they con- fumed. If we are to judge by the laffc article, their proportionate antacid ftrength (for this experiment may be no rule as to their other qualities) is as nine to eight. It appears likewife, that the antacid quality of the afhes themfelves is almoft double to that of the falts. Can this be owing to the volatility of fome acid parts ? or to the greater antacid power of the other part that is mixed with thefe falts ? This laft appears probable from the following experiments, which difcover a ftronger antacid power in the refiduum than in the falts. Let us now examine the refiduum, which, as I mentioned before, was of two forts j what remained in the bottom of the pot, and what remained in the gray paper. The firft was of a light brown colour, and run together into hard pieces 5 the latter was white, and a powder. Exp, Sedl.HL ON BLEACHING. 123 Exp. 30. Thirty grains of the latter ef- fervefced ftrongly with the acid mixture, and confumed five and a half tea-fpoonfuls, Thus, though the refiduum appears ftrong- er than the falts, yet it feems much weak- er in its antacid power than the allies. I poured water on a quantity of both re- fiduums in two different cups, and let it ftand all night. The water had a tafte of chalk and water, next morning, but not of lime-water. This fuhftance might ftill be calcarious, though it had no parts now foluble in wa- ter ; for the reiterated boiling in water might have carried off thefe foluble parts, as we know it does. My next trial, there- fore, was, to fee if I could reduce it to quick-lime again, by the force of the fire. There is no doubt but that the fire will re- duce into quick-lime, at a fecond trial, thofe calcarious parts, which had not got a fufficient fire the firft time, and on that account were not calcined into quick-lime. We often fee undiffolved in the water pieces 0^2 Of i2 4 EXPERIMENTS PartllL of lime-ftone, which would have been re- duced to quick-lime had they got fufficient fire. But whether thofe parts of quick- lime, which have been fufficiently calcined, and have been robbed of all thofe particles that are foluble in water, can again be re- duced to quick-lime, is not, I think, clear- ly afcertained by authors who have wrote on this fubjedL Exp. 3 1 . To determine this queftion, I tried the following experiment. A confix derable quantity of quick-lime was quench- ed in water, fo that it rofe fome inches a- bove the lime. The whole was often fth> red about. After it was completely fettled, I took of the furface of the lime, which was compofed of thofe particles that had been the longeft fufpended in water, and of courfe the fineft. This lime, that could have no particles in it but what had been feparated by the water, and therefore none but thofe that had been changed into quick-lime by the fire, was boiled in wa- ter until it no longer tafted like lime-wa- ter. This took two days boiling. The effete Seft.IIL ON BLEACHING. i2j effete lime was then put into a reverbera^ tory furnace, for an hour and a half. This reduced it again to ftrong quick-lime ; for it fucked up the water very greedily, fell down into powder, and afforded a ftrong lime-water with a pellicle. Exp. 32. Some of the refiduum of the white Mufcovy afhes, put in a ftrong kit- chen-fire for two afternoons, and after- wards mixed with water, did not fall 3 af- ter it had flood fome time, the water had no pellicle; nor a tafte of lime-water, but as if chalk and water had been mixed toge- ther. But the fame fubftance, kept in a re- Verberatory furnace for an hour and a half, gave me a ftrong lime-water with a pellicle. The refiduum then appears to be the caput mortuum of quick-lime. Exp. 33. Another experiment of the fame kind I tried at the bleachfield. I took fome of the caput mortuum^ which remains in the copper after the lye is taken off, and will 126 EXPERIMENTS PartllL Will not diffolve in water. It had no tafte but that of an earth. It was calcined in a large ftrong fire for two hours ; when cold, water was poured on it, which made an ebullition, and caufed it to fall down. When the liquor had ftood all night, it had the pellicle and tafte, though not very ftrong, of lime-water. Let us fee if we cannot make a lime- water from the Mufcovy allies, without the affiftanee of fire. Exp. 34. Two ounces of them were wafhed, by continual addition of frefh water, till the water that came off from them had no longer a fait tafte. Then I poured fome water over them, and let the mixture ftand all night. Next morning it had the pellicle of lime-water; and appeared, on tafting, to be good lime-water, Asa further proof, we could have diftil- led fome of the afhes,. after the falts had been wafhed out, with crude ammoniac fait,- and feen whether the volatile fpirit was like that Scft. IV. ON BLEACHING. 127 that produced from lime and that fait 5 for a fpirit produced in this way, is found to differ very much from a fpirit produced by an alkaline fait in place of lime. But my ingenious friend Dr Cullen has prevented me ; and, having diftilled Mufcovy afhes and fal ammoniac together, got fuch a fpirit as is procured from the latter and quick-lime. By this experiment he made it highly pro- bable, that lime entered into the compofi- tion of the Mufcovy afhes - y and is, therefore^ juftly intitled to the merit of being the firft difcoverer. From thefe experiments the following corollary follows, That the Mufcovy afhes contain an alkaline fait and lime ; and the latter in much greater proportion than the former. SECT. IV. Cafhub afhes. t i ''Hese afhes are extremely hard, of X* the colour of iron ftone, with many fhining 128 EXPERIMENTS PartllL fhining particles, and fome pieces of char- coal in them. They have a faline tafte, with a conliderable degree of pungency. They feel gritty in the mouth, when broke in pieces by the teeth 5 for they will not diffolve. Exp. 35. When the faline mixture was poured over them, they did not effervefce violently, but long ; and the liquor had a very black powder on the top and bottom. They emitted a fulphureous fmell; and, when the faturation was completed, which was done by 13 tea-fpoonfuls of the acid mixture, they had a fulphureous tafte. Exp. 36. To extract the falts, a half- pound was boiled in a pint of water ; then that water poured off, and a half-pint put on the afties again 3 and fo on till the water tailed no longer fait. This boiling took twenty-four hours. The laft that came off had a ftrong tafte of fulphur, and was blackifh. Etfp. 37. To try if there was any fulphur in the deco&ion, I put a piece of filver in- to Seft.IV. ON BLEACHING. 129 to it ; which in a few minutes was turned almoft quite black. Exp. 38. This experiment corroborates the former. Into 1 oz. of the decodtion I poured as much fpirit of nitre as faturated it. During the addition of the fpirit there was a ftrong fmell of a volatile fulphur. The liquor turned la£tefcent, and let fall to the bottom a light-coloured powder in confider- able quantity. I drained the whole through brown paper ; and there was left in it a ful- phureous frnelling fubflance, which, when dried, weighed one fourth of a grain. This fubftance, when burnt on a red-hot iron, had not a blue, but pale-red flame, and a very gentle fmell of burnt fulphur. As this is a vegetable fulphur, that is to fay, an in- flammable body joined to a vegetable, and not a mineral acid ; it probably differs from the mineral fulphur in the ftrength of its qualities, and, therefore, may not have fuch a ftrong fmell as the latter. Let us try if we can afcertain the quan- tity of this fulphureous matter in the decoc- R tioa. i 3 o EXPERIMENTS PartllL tion. It is very volatile, and therefore cannot be caught, fo that we might weigh it. Let us take its power in colouring fil- ver, and fee what light it will afford us in this intricate fcrutiny. The lefs the quan- tity of fulphur, the weaker the colour. I took 3 gr. of fulphur, opened by an alka- line fait, and diluted it fo with water, that the folution had loft all tafte, and took two hours to alter the colour of filver in a fmall degree. The quantity of water ufed was five pints. When two pints more were added, it loft altogether this quality. To apply this experiment to the prefent queftion, Exp. 39. I diluted a fmall quantity of the deco&ion, fo that it took the fame time to have the fame effed:, as in the for- mer trial. The proportion of water to the decodion was, as 192 to 1. There was three pints of the w T hole ; therefore 192 multiplied by 3, gives the quantity that could be made out of the whole decodion of this weak fulphurated mixture, which is 576 pints. So that dividing the number ' of Se6l.IV. ON BLEACHING, tp of pints by 5, and then multiplying them by 3, we have the number of grains of fulphur in this decodtion. The whole then is 5 dr. 35 gr. and about a half, in the decoftion, befides what remains in the refiduum, which feems to be more. E- very bleacher, if he extracts all the falts from the Cajhub afhes, muft have that quantity of fulphur from each half-pound of the afhes ; and if he boils them longer, he will probably have more. The only objection to this reafoning is, That we have argued from a mineral fulphur to a vege- table one, and fuppofed their powers of tinging filver to be the fame. As I cannot pofitively affert them to be the fame, I mufl allow this objedion to have fome weight -> though it is probable there may be little difference betwixt them in this quality. When the deco&ion was boiled into a gill and a half, it did not turn filver black more fpeedily than before boiling ; which fhows the fulphur to be as volatile as the water. This quantity flood for fome days in a cellar, but nofign of any cryftallifation. R 2 It i 3 2 EXPERIMENTS PartllL It was boiled into a gill, and fet by again. After landing twelve days, I looked to it, and found it gellied. This was evaporated, and gave me 10 dr. of a brown fait, that had a ftrong alkaline cauftic tafte. By an- other experiment, in which the falts were feparated by cold water, I got a fmall quantity of a neutral fait, like the vitrio- lated tartar, from thefe afhes. Exp. 40. The alkaline fait, tried with the acid mixture, effervefced, and confu- med four and a half tea-fpoonfuls of it. Thus we find the antacid power of the fait is much weaker, than that of the afhes. I had two refiduums, one left in the pot, and another in the brown paper, of a blackilh colour ; both which weighed 5 oz. 7 dr. The lofs in boiling, then, amounts to 7 dr. Exp. 41. On 1 dr. of the refiduum powdered I poured the acid mixture. An effervefcence arofe ; the whole turned very black, fent up a ftrong fulphureous fmell, and Sedt.IV. ON BLEACHING. 133 and tinged the piece of filver black. Twenty tea-fpoonfuls of the acid were con- fumed. After the faturation there was fome of the earthy part of the refiduum at bottom ; above it lay a black fluff like tar ; then the liquor, which was now pellucid, though it was not fo all the time of effer- vefcence. A black fcum remained on the top till next morning, which then fell to the bottom on ftirring. What remained in the paper, when the liquor was flrained, weighed half a drachm. The liquor be- ing almoft evaporated, was fet to cryftal- lize. After ftanding fome time it was gel- lied. Being evaporated over a flow fire, it gave me 44 gr. of a pale-red faline fub- ftance, but no cryftals. This faline fub- ftance attracted the moifture fo ftrongly, that it could hardly be dried, unlefs put in a ftrong heat ; and, when taken from the fire, turned immediately wet again. It feemed to agree pretty much with the fa- line fubflance that I fpoke of before, com- pofed of lime and fpirit of nitre . Exp, i 3 4 EXPERIMENTS PartllL Exp. 42. Some Cafhiib afhes powdered, and often wafhed with water, fo that the falts were all carried off, were infufed in water. After ftanding fome time, I had a weak lime-water, that had ftill fomewhat of a faline tafie, and had no pellicle. Exp. 43. Some of the refiduum was put into a reverberatory furnace for two hours. After that it afforded me a good lime-wa- ter. Cajhub afhes, then, appear to contain an earth half vitrified, fome lime, alkaline falts, and a fulphureous, inflammable, vo- latile fubftance. Let us inquire whence arifes the ful- phur of thefe afhes, of what fort it is, and what are its effects. Sulphur is a com- pofition of the acid of vitriol, and an oil. Any kind of oil will ferve, whether vege- table or mineral, and make no difference in the compofition ; but no acid will do except that of vitriol. The acid of mofl trees feems to be of the vitriolic kind. When they are burnt, the fire difpels all the watery parts, with fome of the acid, and the Scft. IV. ON BLEACHING. 135 the more volatile oils 5 while the remaining acid, more concentrated by looting the watery particles, unites with the heavy oils, and fo forms a fulphur ; which remains in the afhes, if the fire is not fufficiently ftrong, or not continued long enough to confume it ; for all charcoal, if fufed with alkaline falts, difcovers a fulphur. It is re- markable, that charcoal does not tinge filver when rubbed on it, nor fhows any other of the effedts of fulphur, until it has been opened by an alkaline fait. All thefe materials are found in the Cajhub afhes y and therefore no wonder that they contain a fulphur. But does this vegetable appear to be the fame with the common mineral fulphur ? HO MB ERG has given us a divifion of fulphurs into the vegetable, the animal, the bituminous, and the mineral ; and has milled many by it. That Homberg means the in- flammable principle by the word fulphur, appears from thefe Words. Uhuile de la plant, i 3 6 EXPERIMENTS Partlll. plant, qui eft leur matiere fulfureufe *. — He was to blame, as well as moft of the chv- mifts have been, for the vague ufe of that word. That divifion, therefore, cannot af- fect the prefent queftion. It is plain that common fulphur may be made as well with a vegetable as with a fof- fil oil. The acid of vegetables feems to be of the fame nature as that of vitriol ; for with the acid of fome vegetables and the fait of tartar, a tartarus vitriolatus arifes ; and with iron or copper, a vitriol of thefe metals. The acid of many plants feems to differ from that of vitriol, only becaufe the former is weaker than the latter, It would appear, therefore, that vegetable fulphur would no wife differ from mineral but in being weaker. The effeft of this fubftance upon cloth is to difcolour it ; as every bleacher knows, if he ufes a lye of kelp afhes, or any other fort of afhes much impregnated with ful- * Mem. de V acad. des /dene. phur, Sfeft. IV. ON BLEACHING. 137 phur, when the cloth has attained a confi- derable degree of whitenefs. Let none, however, imagine, that this fulphureous fub- ftance tinges linen, as much as it does fil- ver. This is an effed: peculiar to that me- tal. Sulphur, when mixed with alkaline falts, is foluble in water, and may in that ftate be taken out of the cloth by mill-wafh- ing. But if the alkaline falts are feparated from the fulphur, by their ftronger tenden- cy to folution, by their tranfmutation into an abforbent earth, by meeting with an a~ cid in the water thrown on them, or in the operation of fouring, the fulphureous mat- ter, freed from its alkaline dilfolvent, will be precipitated on the furface of the cloth > nor will water have the leaffc efre£t in re- moving it. A pure lye would again diffolve this fulphur ; but the continuation of an impure one muft increafe its quantity. Hence the neceffity of a greater evaporation, and longer expofition to the fun and winds ; the only method left, during the ufe of a foul lye, to carry off thefe colouring fulphu- reous particles. S S E C T. 138 EXPERIMENTS Partlll. SECT. V. Marc oft ajl:es. THE Marcoft afhes are of a paler co- cour than the former, and have fome fmall pieces of charcoal in their com- pofition. They have a ftrong faline tafte, with fo great pungency, that they cannot be held long in the mouth. 'Exp. 44. The acid mixture kept up a long fermentation, but not a violent one. A dark-coloured fubftance rofe to the far- face, and likewife lay at the bottom on the furface of the afhes. A ftrong fulphureous fmell arofe ; and after faturation, which was performed by 13 tea-fpoonfuls, the liquor had a fulphureous tafte. Exp. 45. Half a pound was boiled as the former, and during the fame time. The deccdtion was not fo black as the Cajhub, and had not the fulphureous fmell. I for- got to try it when turbid j but the ftrained decodlion, Seft.V. ON BLEACHING. 139 deco£tion, having fome of the refiduum left in the paper mixed with it, had no effedfc on filver. One ounce, therefore, of Marcoft afhes was boiled in a pint of water to half the quantity. This deco&ion coloured filver very fuddenly; and when faturated with ipirit of nitre, let fall a great deal of fedi- ment. When diluted with 96 waters, it juffc tindtured filver. So that the Marcoft feems to contain about the half of the fulphur that the Cajhub afhes do. The former decodtion boiled into two gills, did not tindlure filver. It appears by thefe experiments, that the fulphur in this fait is much more volatile than the former, and that the whole of it, by continued boil- ing, may be diffipated. On this account it feems fitter for bleaching. The decodion having Hood fome days, and giving no fign of any other fait, was boiled into a gill. This fet by for twelve days, turned into a gelly. When entirely evaporated, I had of a faline fubftance 1 1 dr. 1 fcrup. and 2 gr. S 2 which r 4 o EXPERIMENTS Part III. which added to 5^ oz. of refiduum, fhow- ed the lofs to be 1 oz. 38 gr. By another experiment, in which the falts were fepara- ted by an infufion of cold water, I got a fmall quantity of a neutral fait, like the tar- tarus vitriolatus. Exp. 46. This fait procured by the for- mer experiment, taftes ftrongly alkaline , and a half-drachm took 4 tea-fpoonfuls of the faline mixture to faturate it. During the effervefcence I thought I felt a fulphu- reous fmell. The refiduum was much of the fame colour with the afhes j and is quite infipid and undiffolvable in the mouth. Exp. 47. On 1 dr. of it I poured the acid mixture, which railed an effervefcence much greater than the refiduum of the Ca~ jldub 5 but did not turn black, nor fend up a fulphureous fmell, nor tinge filver. It confumed 26 ipoonfuls. After faturation, there was a black tar-like fubftance refting oji the remaining powder. The liquor, be- ing 8e£fc.V. ON BLEACHING. 141 ing ftrained, left 7 gr. of refiduum. When evaporated, I had 1 dr. 9 gr. of a faline fubftance, that would not cryftallize, had a greenifh yellow colour, and attracted the moifture ftrongly from the air. The ant- acid quality, therefore, of the earthy part, is to the fame quality of the faline part, as Exp. 4.8. To difcover whether the refi- duum was a calcarious earth, a half-ounce was put for an hour and a half in a reverbe- ratory furnace, during which time it loft 1 dr. and 1 fcrup. When put into water, it did not hifs when mixed ; yet next morn- ing I had a ftrong lime-water, with a pel- licle from it. Exp. 49. To try if I could difcover any lime in the afhes themfelves, without the affiftance of fire, I wafhed the falts well out with water, after which they afforded me a weak lime-water. This fait, therefore, feems to contain the fame principles with the former ; only the i 4 2 EXPERIMENTS PartllL the fulphur is in lefs quantity, and more vo- latile. It is proper here to inquire, whether al- kaline falts produced from different bodies, ditfer from one another ? In examining this fad:, chymifts generally ftate the queftion thus : " Have alkaline falts any fpecific dif- cc ference ?" Almoft all of them determine in the negative." Stahl fays, Fund. Chym. p. 8 5 . Nit rum itaque plantarum y cum generali ilia oleofitate crajfa feu refma y conjlagrando y in omnibus vegetahilibus y quce alkali fundunt y u- nius generis alkali conjlituit. They allow, that one fait is more cauftic than another, that one is more pure than another y but this, fay they, is owing to the accidental management of the fire, or the accidental mixture of other bodies. They all allow, that falts extracted with tepid water, are not fo impure, as thofe with boiling water. The quicker or flower evaporation is obferved to make a difference. But thefe caufes are ftill accidental. The Joda Hifpanica is obferved to make finer glafs, than the much purer fait of tartar. But this is owing to a mix- ture Sedt.V. ON BLEACHING. 143 ture of fea fait with the Spanijh kelp afhes, and a mixture of inflammable matter with the fait of tartar. Many other differences are obferved betwixt the different alkaline falts ; but thefe, they fay, are owing to ac- cidental, and not to fpecific qualities. Let us underftand the terms of the queftion aright, before we argue on it. The queftion is thus ftated by Stahl. An ut plant ce^ • it a etiam eamm J alia jixa, fpecie et fpecifico effeSlu differunt * ? If he means to inquire, whether thefe falts have the fpecific qualities of the plants from which they are got ? the queftion will foon be de- termined in the negative. For the fait of poppy enjoys no narcotic quality, nor the fait of ipecacuahn an emetic, nor the fait of jallap a purgative, nor the fait of hemlock a poifonous. But if he means that one kind of alkaline falts have no fpecific qua- lities, whereby they differ from another kind, and which the latter, treated the fame way, may not acquire % and this, by * Fundam, Chym. p. 85. the i 4 4 EXPERIMENTS PartllL the quotation preceding the laft, feems to be his opinion ; I muft, determined by a variety of experiments made by others, diffent from fuch a great chymifl, and af* fert, that " alkaline falts have a fpeeific cc difference." Experiment alone can de-* termine this point, and to experiment I {hall refer the decifion. The alkaline bafe of fea fait is found to enjoy fome particular properties, which no other alkaline fait has. It cryftallifes like the neutral falts. It does not turn moift in the air ; but, on the contrary, lofes that water which cryjftallifed along with it, and, of courfe, its tranfparency. When it is combined, and faturated with the vitriolic acid, it forms Glauber's fait; a fait differing in the figure of its cryftals, its eafy folu- tion in water, and fufion in the fire, from vitriolated tartar, or a fait made of the fame fpirit of vitriol and the fait of tartar. When it is faturated with the fpirit of nitre, there arifes a neutral fait, differing from nitre, as it powerfully attracts humidity ; and its cryflals are of a quadrangular figure. HOFFMAN SeaV. ON BLEACHING 145 HOFFMAN, in his 29th obfervation, lias fhown us how differently experiments fucceed with different alkaline falts. The alkaline fait of nitre prepared with charcoal, exhaled the fmell of aqua forth on an effu- jion of fpirit of vitriol - y which fait of tartar^ .or potafhes, do not ; owing perhaps to fome of the fpirit of nitre that is not difpelled by the deflagration. If powder of charcoal is added to fait of tartar, or potafhes in fufion, a fort of hepar fulphuris is formed ; but this does not fucceed with the alkaline falts made of nitre and charcoal, or nitre and the regulus of antimony. Salt of tartar, made with or without nitre, differs from the lixivial falts 5 for, on an effulion of oil of vitriol, a fetid fmell arifes, a black fcum gathers on the top, and the whole mixture at laft gains the fame colour. The fait made of two parts nitre and one of the regulus of antimony, affords a red tindture with fpirit of wine ; which a fait formed of two parts of nitre and one of tartar, or the .common potafhes, do not. Thefe fpecific differences in the falts of the two laft ex- periments, feem to be owing to fome of the T oily 146 EXPERIMENTS PartllL oily or fulphureous particles, which ftill lurk in them, notwithftanding all the fire they have fuftained. It appears, then, from thefe experiments, that alkaline falts prepared in the com- mon way, from different fubftances, are fpecifically different; and probably have different effects when taken into the hu- man body ; but thefe effe£ts are fo gentle, and fo mattered by the alkaline property common to all, that they pafs unobferved. The fire at .length feems to diffipate thefe fpecific properties, and to reduce the dif- ferent alkaline falts, freed from heteroge- neous particles, to one fimilar nature. The purer thefe falts are, fo much the fitter are they for the ufes of bleaching. The effects of the fulphur in the Cajhub and Marcoft afhes, have already been explained, The great quantity of fea fait which is in kelp afhes, may render them unfit for bleaching. But this flill ftands in need of further proof. I do not think that any o- ther fmall differences betwixt thefe alkaline falts can affedt their operation on cloth \ be- caufe Seft. VI. ON BLEACHING. 147 caufe that depends entirely on their alka- line property, which can only differ in de- gree. SECT. VI. Method of manufaSluring thefe afhes at home. ALL reafoning and experiment ought to be connected with the affairs of mankind; and the clofer this connec- tion is, the more valuable thefe efforts of the human mind become. It is by this conlideration alone their value ought, and will be meafured. But what can touch us more nearly than the improvement of our manufactures, on which the riches of our country, and the daily bread of the greatefl number of its inhabitants depend ? With this view, then, I fhall endeavour to make the foregoing experiments more ufeful, and adapt them to the advancement of bleaching, by difcovering how we may make thefe afhes, at a much cheaper rate, •amongft ourfelves, while we employ our T 2 own i4& EXPERIMENTS PartllX. own hands, and thereby fave the nation much money. By fhowing how thefe afhes may be compounded, we fhall be able to give the preceding conclufions their full conviction . The blue and white pearl allies we have difcovered to be pure alkaline falts, with- out any confiderable mixture of heteroge- neous bodies. Their purity fhows the lixive to have been ftrained through fome clofe fubftance, fuch as linen, or flannel. The blue afhes fhew, by their colour, that they have fuftained the moft fire. But both of them are fo much alike, that the one may be fubftituted for the other ; and therefore we (hall confider them in one view. Every one knows, that alkaline faltsv fuch as thefe, are got from all plants except the alkalefcent, and from all trees except the moft refinous, which afford them in very fmall quantity. Thefe plants, or trees, when found, are pulled or felled in the fpring, dried, and burnt to afhes. By the effufion of warm water the falts are dif > folvecly Sedt. VI. ON BLEACHING. 149 folved, and, by ftraining, feparated from the earth along with the water. This fa- line liquor, which is called a lixive, is eva- porated over a fire ; and what remains, is an alkaline fait of the fame kind with the pearl afhes. I was informed by a fkilfhl bleacher in Ireland, that he pradtifed a more expeditious way of extracting the falts. He bought the afhes of different vegetables from the commonalty for 9 s. a-bufhel. From thefe a very ftrong lye was made, into which dry ftraw was dipped, until it fucked up all the lye. This ftraw was afterwards dried and burnt, and gave him falts which he fhowed me, almoft as good and pure as the pearl afhes. This method I have feveral times tried ; but could never burn the ftraw to white afhes* the falts diminifhing the in- flammability of the ftraw. It is a very ex- peditious method, if it can be pra&ifed. But I can fee no occafion for bringing the lye into a folid form, as the falts muft again be dilfolved in water before they can be ufed* 150 EXPERIMENTS Part III, ufed. The ftrength of the lye can eafily be determined by the hydroftaticd balance. Though I make no queftion, that the quantity of fait, in plants of the fame fpe- cies, will vary in different foils and climates 5 yet it Would be of advantage to have the proportion afcertained in general. Some trials of this kind I have made. Exp. 50. Two pounds of fern which had been pulled Auguji 16. were dried, and burnt to white afhes. Thefe weighed 7 dr. and tafled very fait. When lixiviated, ftrained, and evaporated, they gave me 49 gr. of fait, about the eighth part of the afhes. If the fern had been pulled in April, it would have afforded more fait. Why then fhould we not prepare falts from this vegetable ? There is more of it growing on our hills, than would ferve all our bleachfields. The Irijh make great ufe of it. Exp. 51. From 11 oz. of tobacco afhes I had 1 oz. of fait. Two oz. of peat afhes afforded half a drachm of fait. Nettles, I am Sedl. VI. ON BLEACHING. 151 am informed, afford much fait. Furz and broom, natives of this country, are very fit for this purpofe. But the kelp, as it grows infuch plenty along our £hore, and contains more falts than any other vegetable I know, would be the moft proper, were it not for a mixture of fome fubftance that renders it unfit for bleaching, at leaft of fine cloths, after they have attained a tolerable degree of white- nefs. It is obferved by bleachers, that, in thefe circumftances, it leaves a great yellow- nefs in the linen. As thefe afhes are much ufed in Ireland, and as it is not uncommon to bleach coarfe cloths with them in Scot- land, a difquifition into their nature, and fome attempts to purify them, may not be improper. There are no afhes fold fo cheap as thefe ; for the beft gives but 2 /. the 2000 weight. They may, therefore, allow of more labour to be expended on them, and come cheaper at long-run than the foreign falts. Exp. 52.I dried fome fea-ware, and burnt it, i 5 2 EXPERIMENTS Part III. it, though I found that laft operation very difficult. When I had kept them fufed in the fire for two hours, they weighed 3-^ oz. I poured on the afhes an EngliJJj pint and a half of cold water, that I might have as little of the fulphur as poffible. This lye, after it had ftood for fome hours, was pour- ed off clear, and had but a flight tendency to a green colour. I made a fecond infu- fion with milk-warm water, and poured it off from the fediment. This had a dark- er colour than the former, was kept fepa- rated from the former, and evaporated by itfelf. There was a third infulion made ; but having no fait tafte, it was thrown a- way. The fecond infulion feemed to con- tain more fulphur than the firft - y and a piece of white linen kept in it half an hour, while it was boiling, was tinged yellow, and could not be wafhed white again. The earthy part remaining, weighed, when well dried, 1 oz. 2 dr. The faline decoc- tion, evaporated by degrees, and fet at dif- ferent times in a cellar to cryftallize, afford- ed me 5 dr. 46 gr. The liquor, when entirely evaporated, left 44 dr. of a yellow fait, Se6l. VI. ON BLEACHING. 153 fait, which appeared to be a ftrong alkaline. The falts which cryftallifed feemed to be moftly fea fait, with a confiderable quantity of fulphur, and fome alkaline fait. There appeared no figns of the bittern in thefe falts, as their folution did not turn turbid with the oil of tartar. Nor was any of the bittern to be expected in kelp afhes, although it pro- bably is to be found in the recent vegetable ; becaufe the alkaline falts formed by the fire, muft have changed it into a neutral. The lye made with warm water, being e- vaporated, left 4 dr. of a black bitter fait, which, from its quantity of fulphur, appear- ed unfit for bleaching. Thefe afhes, then, feem to be a compofition of fomewhat lefs than the fourth of fulphur, the fame quan- tity of fea fait, about a fourth of alkaline fait, and fomewhat more than a fourth of earth. The alkaline fait contained in kelp afhes, amounts to one penny a pound. This cheapnefs makes it worth our pains to be- ftow fome labour on them. If the bad effeds in bleaching with kelp afhes arife from the fea fait, as fome of the U moft i 5 4 EXPERIMENTS PartllL moil knowing bleachers think, they can be freed from it in an eafy manner. Let a li- xive of kelp afhes be made with cold water, for that does not extrad: fo much of the ful- phur 5 it mull ftand but a fhort time, for thefe falts dilfolve eafily ; decant it, and eva- porate the lye. As the boiling continues, the fea fait will cryftallize. When that is all feparated, the remaining lye will contain alkaline fait with lome fulphur. This ope- ration eyery matter of a bleachfield may learn and overfee, without taking up much of his time. A fimilar procefs is carried on by common fervants in the allum-works, who have by practice learned it from others. I had fome hopes that the fulphur might be carried off by long roafting, fuch as thefe falts undergo, before they are fufed, in or- der to be turned into glafs ; becaufe I had obferved, that the longer time they were kept in the fire, the freer were they from this fulphureous part. Exp. 53. I ordered a quantity of kelp afhes to be kept in the furnace of a glafs- houfe, Sed. VI. ON BLEACHING. 155 houfe, where the heat was juft below the vitrifying point, for twenty-four hours. Du- ring this time they had loft almoft four fifths of their weight. They were now much freer from their fulphur, and were of a light colour ; but much of the alkaline fait had been driven off with the oils. If a lye is much impregnated with this fulphure- ous matter, it appears to be carried off, in a great meafure, by long boiling. If we cannot get thefe alkaline falts at home in fufficient quantity, our plantations are ready to afford them, if we are not wanting in induftry. Our colonies would gain health and riches by the traffic, and we fhould be provided more certainly, and at a much cheaper rate. The hiccery wood, we are told, affords great plenty of this fait. The only way to fet on foot fuch a trade as this, would be to fend from this people fkilled in the manufacture, with fuch pro- per encouragement, for a certain number of years, as the wifdom of parliament (hall think fit. We 156 EXPERIMENTS PartllL We come now to explain the method of manufacturing the white Mufcovy afhes. We have fhown, by undoubted experiments, that the greateft part of thefe afhes coniifts of lime ; and yet we have feveral adts of parliament which forbid the ufe of that ma- terial under fevere penalties. The parlia- ment were in the right to difcharge its ufe, upon the difadvantageous reports which were made to them. We fhall immediate- ly fee, how dangerous a material it is when ufed improperly, or without the mixture of alkaline falts, which render it fafe, and more foluble in water. But I'll venture to fay, that experiment will not fupport the pre- judice entertained with regard to it, if car- ried any further. Since bleaching, then, cannot be carried on without it ; for thofe afhes which con- tain it, are quite neceffary in that operation j and fmce we import them from foreign countries y let thefe prejudices againfi it ceafe ; and let us only conlider how we may render our own lime as fafe as the foreign. If we can do that, the wifdom of the legis- lature Sed. VI. ON BLEACHING. i 57 lature will be as ready to abrogate thefe adts, as they were to make them. By my experiments on the white Muf- covy afhes, I got about the eighth part of al- kaline falts from them. This made me ex- pe£t, that, by mixing in the fame propor- tion quick-lime and alkaline falts, I fhould be able to produce Mufcovy afhes. Exp. 54. To an ounce of quick-lime and a drachm of white pearl afhes, I added a- bout a gill of water, and boiled them toge- ther till the water was all evaporated. The tafte of this fubflance was little different from lime. To recover the falts again from the lime, I diffolved it in water, ftrained off the liquor, and evaporated it. Inftead of the drachm of falts, I had but 2 gr. of a fubflance which was more earthy than fa- line. Exp. 55. To 3 dr. of quick-lime, and as much potafhes, I added a mutchkin of water, and kept it boiling for two hours till it was evaporated. I diflblved it again in water, i 5 8 EXPERIMENTS PartllL water, which being filtered and evapora- ted, gave me i~ dr. of a cauffcic fait, that liquified in the air, when it had been but four minutes from the fire. It appears, then, that the alkaline falts are deftroyed by lime, and that a great part of them can never be again recovered. They muft be reduced to an unfoluble fubftance. From the remaining lime, after the falts were ex- tracted, I got ftrong lime-water, but with- out a pellicle. This fliows, that a quanti- ty of alkaline falts, equal to the lime, boil- ed with it for two hours, are not able to fix all the foluble part of the lime. From thefe experiments we may draw fome corollaries with regard to the prefent fubjeCt. i/?, That evaporating the water from the lime and falts by boiling, is a moll: unfrugal way of preparing thefe white afhes. 2dly, That thefe afhes ought to be kept clofe fhut up in cafks ; for if expofed to the open air, though in a room, the alter- nate moifture and drought muft fix their moft ufeful parts. This I have found to be fadlj for the falts that I made, became lefs pungent Sea. VI. ON BLEACHING. 159 pungent by keeping ; and I have obferved, that the furface of the Mufcovy afhes loft all pungency, by being expofed to the air, while their internal parts ftill retained it. ^dly, That all boiling is prejudicial to thefe Mufcovy afhes, as it fixes, and that quickly, their moft fubtile, and probably their moft ferviceable parts. Let us now proceed to another method of making thefe white afhes. I imagined, that if the falts were difiblved in water, and the quick-lime flaked with that, the mafs would foon dry without the affiftance of fire. In this way I added equal parts of both ; but the compofition was fo ftrong, that it bliftered my tongue, if it but touch- ed it. When the fourth part was alkaline fait, it bliftered my tongue, when kept to it a few feconds. I could tafte the falts plain- ly in the compofition, when they made but the thirty-fecond part of the whole. I thought, when compofed with the eigh- teenth part of fait, it had, when frefti made, juft the tafte and look of the Muf- covy 160 EXPERIMENTS Partlll. covy afhes ; nor could any perfon have dif- tinguifhed them. This I once imagined was the proportion ; but when I found that the faline pungency foon turned weaker by keeping, and that this compofition would not afford the fame quantity of falts that the Mufcovy afhes did, I faw that a much greater quantity of falts was neceffary. The proportion appears to be one of fait to four of lime, prepared in the laft way. Three drachms of afhes prepared in this way, and kept for a fortnight, gave me but 1 5 grains of fait ; which is but the half of what the Mufcovy would have afforded. I find, if the quick-lime is firft quenched, it does not fix the falts fo much ; and there- fore is better, and cheaper. One drachm of potafhes diffolved in a little water, and added to 3 drachms of quenched lime, gave me 44 grains of a very cauftic fait. I prefer this method as the beft. The manufacturers.- of this fait proba- bly pour the lixive upon the lime, as they can know by its fpecific gravity what quan- tity of falts is in the water , and fo fave themfelves Sea VI. ON BLEACHING. 161 themfelves the expence of procuring the falts in a dry form. There is now Only one proof wanting to fhow, that thefe are as good as the fo- reign Mufcovy afhes, viz. their anfwering as well in the bleachfield. I fent fome that I had made to Mr "John Chryftie, and had the following account of their efFedts in the bleachfield. " The fmall parcel of afhes " which I got from thee, appear to be " very good, and in all refpe&s anfwer the " purpofes of the Mufcovy white or blanch l£ afhes. They are juft what goes by *< the name of Riga Mufcavy blue afhes ; w which are the beft of that kind. I am * c fo well fatisfied of their anfwering, that This, in the Doctor's opinion, is the method of making the potafhes that come from Sweden, Ruf- fiu, afid Dantzick: and that there is no other difference betwixt the afhes made in thofe different countries, but that the Ruf- fian, containing more fait, muft be made into a pafte with a ftrong lye. There would appear, by my experi- ments, a greater difference than this, be- twixt the Swedip afhes, if that is the true procefs, and thofe I have examined. I had difcovered the greateft part of the Muf CO r CM Sed. VI. ON BLEACHING, 165 covy afhes to be lime. I fufpedted it might enter into the compofition of the Marcoft and Cajlnib \ and have accordingly difcover- ed it there. Without the fame grounds, none would ever have fearched for it. Whence then comes this lime ? It muft ei- ther enter into its cornpofition, or arife from the materials managed according as the procefs directs. Let us examine this queftion thoroughly, as it is a queftion of great moment, and nearly concerns the manufacture of thefe falts. There are two paffages in chymical au- thors, that w r ould induce one to believe a very cauftic fubftance might arife from the terreftrial part of vegetables fluxed with the faline. Thus Junker > Cineres ligni hitulini recentes, et per crib mm trajeSii^ fi aqua hu- me£lantur> et globi^ injiar pomorum^ exinde conjiciantur^ dum cefiu intenfore glohi exjiccan- tur, pojiea igni ejufdem ligni fiammante can- dejiunt, denique adhuc calidi aqua pura co- quuntur ; lixivium filtratum^ et ad confiften- tiam faturati Uxivii evaporatum^ tide® acre redditur^ tit lanam injeWkm in mucum refol- 1 66 EXPERIMENTS Part III. vet , fulphur quoque brevi folvere foleat> licet in frigidum lixivium conjiciatur. The other quotation is from Stabl. Caujlicum Jit alkali maritatwn cum terra fua propria^ cinere pin- guid Ji cinere s ex lignis nitrofis, e. g. bitidino y Jenifer hume&ati, denuo urantur fammeo ig?ti, fat deinde mox elixetur et coagidetur *„ Both thefe chymifts, I believe, have form- ed this opinion, on difcovering the cauftic effe&s of thefe German afhes ; but have ta- ken the procefs of making them on the faith of others. There is no perfon who has dealt in chymical operations, but muft have found the effed: of his experi- ments very different from what the chymifts made him exped:. I have often been de- ceived > and therefore fulpend my belief till my own experience can determine my opinion. I have tried the birch afhes made into a pafte v/ith water. I have tried com- mon charcoal, made into a pafte with a third part of potafhes, and kept them in a ftrong reverberatory heat for fome hours, and yet no fuch cauftic fubftance appeared. ** Vid. Stahl fpecim. Buchan. p. II. f. I. m. i. N°58* I Seft. VI. ON BLEACHING. 167 I have kept the earth and falts of kelp afhes fufed together for twenty-four hours in the furnace of a glafs-houfe, where the heat was but juft below the degree of vitrification ; and yet no remarkable caufticity appeared, afterwards, in the concreted mafs. But fup- pofing that there did, will ever this account for the generation of lime ? Thefe chymifts do not aflert that it is a calcarious caufticity. The earth of vegetables kept in fufion with their falts, is fo far from turning into a quick-lime, that the mafs takes the oppo- fite courfe, and becomes glafs. Bodies that, by the laws of nature, are vitrefcible, can never, fo far as we know, become calcari- ous. In one or other of thefe two fub- ftances all bodies terminate, that are changeable by fire 5 and vegetables are of the former kind. Here it may be afked, Why then, fince they endure fuch a fire, are they not vitrified ? The objedtion would be juft, did they contain nothing elfe but what was found in vegetables. But if we once allow, that lime is one of the mate- rials, the difficulty is eafily folved : for lime, we know, in proportion as it is mixed, hin- ders 168 EXPERIMENTS PartllL ders the vitrification of all bodies. In ef- fe£t, the earthy part in thefe afhes is almoft vitrified ; and I think that I have carried the vitrification yet farther in that part ; but I never was able, with the utmoft heat of a reverberatory furnace, continued for fix hours, to produce any thing like a thorough vitrification in thefe afhes. The heat of the fire ufed in the procefs, would feem to be very great ; and muft, if it were not very difficult, reduce them to glafs. The invi- trefcible nature of thefe falts, fo far from being an objection, becomes a ftfong proof of my opinion* These falts have a remarkable pungency* This we have already feen is the natural ef- fect of quick-lime on falts. These falts are found to be the fittefl for making foap, and to incorporate fooneft and beft with oils. Salts, we know, of them- felves do not readily unite with oil -> but when once mixed with quick-lime, they have a greater tendency to union. Again, Sed. VI. ON BLEACHING. 169 Again, I find that thefe afhes are more eafily fluxed than charcoal made into a parte with the third part fait ; which is much more than thefe afhes contain. Now, it is obferved, that quick-lime increafes the fluxing power of alkaline falts ; for the common cauftic made of quick-lime and al- kaline falts, is fooner fufed than the latter alone. From thefe reafons, and the experiments that difcover lime in thefe afhes, I am led to think, that it is not generated by the pro- cefs, but mixed with the afhes when they are made into a parte. The following ex- periment is a convincing proof of what I have been endeavouring to make out. Exp. 56, I boiled fome peafe ftraw in a ftrong lye of pearl afhes, burnt it into a black coal, and made it into a parte with water. Another quantity of ftraw was boil- ed in a lye made of one part quick-lime, and four parts pearl falts, the lye being poured off turbid from the lime. This ftraw was likewife burnt when dry, and made in- Y to 1 7 o EXPERIMENTS Part III. to a pafte. Thefe two fubftances were put into feparate crucibles, and fluxed in a re- verberatory furnace. The latter appeared to refemble the Marcoft and Cajloub aflhtes, more than the former, which feemed to want their pungency. Long after I was iatisfied this was the way of manufacturing thefe northern afhes, I accidentally met with an obfervation of a knowing bleacher. Mr Chryftie fays, that he was told by Mr Robert Douglas, who had been in Ru/Jia, Sweden, and many o- ther parts, that he had feen the following method of making afhes pradtifed. " The cc afhes of burnt wood or weeds w r ere mix- " ed with quick-lime, put into a fat or re- €C ceiver, and a very ftrong lye was drawn " from them by water, juft as bleachers u make their lye. In this lye dried wood is not weakened, and weighs 42 gr. It appears, then, that the corroding power of lime and Mufcovy afhes is not weakened by foap. That I might fee if foap had any effedi on lime and falts mixed in equal quantities, Exp. 8 5. Sept. 23. Sixteen grains of cloth were put into 2 oz. of water, in which was diffolved half a drachm of falts, that had been procured from equal parts of quick- lime and ,pearl afhes. The fame quantity of cloth was put into another mixture of the Seal. ON BLEACHING. zo 5 the fame kind, with the addition of half a drachm of foap. Nov. 15. Both pieces of an equal colour, both ftrong, and both had loll 1 gr. That in the foap was fofteft. I have in thefe experiments related the fads as they appeared to me, and not the conclufions which may be drawn from them. Experiments, and the reafonings on them, ought, in my opinion, always to be kept fe- parated, that every one may have it in his power to judge, whether the latter natural- ly and juftly arife from the former. Let us how fee what aphorifms or corollaries may be fairly drawn from the foregoing experi- ments. I could wifh more of thefe had been made, that thofe might have been efta- blifhed with a greater degree of certainty. I endeavoured to fupply their number by their accuracy ; for thefe experiments were all repeated a fecond time. The firft ac- counts of all arts and fciences, have ever been imperfed j that will be excufe fuffi- cicnt for what failings are met with here. But let it be remembered, that thefe firft rude attempts have pufhed on and helped others 2 o6 EXPERIMENTS Part IV, others to bring thefe arts to greater perfec- tion. Corol. i . Water appears by Exp. 67. & 8 1. to diflblve fomething in the cloth, to make it lighter, and to have a power, though a weak one, to whiten cloth. If brought to boil, it would feem to have a tendency to weaken cloth. Water, then, may juftly be ranked amongft the bleaching menftruums. Cor. 2. The mineral acid fpirits, viz. oil of vitriol, fpirit of nitre, and fpirit of fea fait, when diluted with a fufficient quantity of water, extract from the cloth fomewhat of an oozy fubflance, heavier than the acid mixture, as moft- of it falls to the bottom; whiten cloth, though not ftrongly 5 and do not weaken it. The oil of vitriol whiten* moft, fpirit of nitre next, and fpirit of fest fait the leaft of the three. They likewife make the cloth rough and hard. Cor. 3. Pearl afhes extradl fomething from . the cloth ; fend up a confiderable quantity of air-bubbles during the folution ; make Seft. I. ON BLEACHING. 207 make it whiter, though with a yellow caft ; but do not feem to have any tendency to weaken cloth when kept in the lye. Their power of whitening is ftronger than that of the mineral acids, but not fo ftrong as lime, or a mixture of lime and pearl afhes. I never could difcover that they weakened cloth in the leaft, although it was dried with the lye in it. This is contrary to the general opinion. The reddiih colour that the lye acquires, and gives to cloth, arifes from the particular a£tion of alkaline falts on the juice of vegetables : for it will appear afterwards, that lint fteeped in water, af- fords a pale-coloured tincture ; but when- ever alkaline falts are added to it, the tinc- ture becomes red. The colour, then, is no fufficient proof of the ftrength of fuch tinc- tures as are drawn with alkaline falts. Dr Hales has obferved, that alkaline falts, though they have no effedl on the hard calculi formed in the human bladder or kidnies, will dilfolve the foft ftones that #re found in the gall-bladder. Cor. 208 EXPERIMENTS Part IV. Cor. 4. Mufcovy afhes have a remarkable power in whitening cloth, but they weaken it much. A bleacher told me, that he once attempted to bleach with thefe afhes alone, but all his cloth was foon eat into holes. Cor. 5. Marcoft afhes extradl more from the cloth, whiten it more, and weaken it lefs, than Mufcovy afhes do when ufed in the fame quantity. The cloth in Exp. 59. was rather weaker than that in Exp. 58. j but there was a half more of the Marcoft than of the Mufcovy afhes. Cafaub gives cloth a redder dye than the former, and weakens it as much. Cor. 6. Stone-lime water whitens more, though it gives the cloth a yellow caft, weakens more, and extradls more out of the cloth, than any of the former materials, This is fufficient to deter any perfon from ufing this material by itfelf. Cor. 7. Oyfter-fhell lime water enjoys all thefe properties in a much ftronger degree than the ftone-lime water 5 and therefore ought Seal. ON BLEACHING. 209 ought to be deemed the moil: expeditious, but moft dangerous material for bleaching that is yet known. Cor. 8. Alkaline falts added to lime, di~ minifh its power of weakening and corro- ding cloth ; and that in proportion to the quantity of thefe falts added to the lime. This compofition, as it is not fo dangerous as lime alone, fo it is not fo expeditious in whitening. When equal parts of each are ufed, the whitening power is ftrong, and the weakening power not very confiderable ; fo that I imagine they might be jufed with fafety, in the proportion of one part of lime to four of pure alkaline falts, to bleach cloth. This fully accounts for an obfervation made by all bleachers, That the bleaching falts, when mixed together, operate fafer and better, than when ufed feparately. For the corrofive power of the Mufcovy, Marco ft ^ and Cajhub afhes is corre&ed by the pearl afhes, and the whitening quality of the lat- ter is increafed by that of the former. There is not a more corroding fiib- D d fiance, 2io EXPERIMENTS PartlV. ftance, with regard to animals, than alka- line falts and lime joined together, efpecially when fufed in the fire. This is the com- pofition of the common cauftic. But lime, and lime-water alone, preferve animal fub- ftances in -a found entire ftate. It appears then very furprifing, that falts and lime fhould be found fo little deftrudtive to cloth, when lime, or lime-water alone, deftroy it fo remarkably. And yet this appears perhaps ftronger than any other fadt, from the whole of the foregoing experiments. So danger- ous it is to depend altogether on analogical reafoning. This corollary is further confirmed, if that is necefiary, by a paper which, by ac- cident, fell into my hands long before I had made thefe experiments. It lays down a method of bleaching fafely with lime, as pra&ifed by the perfon who wrote it. My prejudices were fo ftrong againffc the ufe of lime, in any fhape, before I had tried thefe experiments, that I had not then fo good an opinion of the method, as I now have. As it Seft.L ON BLEACHING. 211 it contains many judicious obfervations, I lhall give it as it was delivered me. Method of bleaching with lime. xc Fir ft) I fteep the cloth in warm wa- " ter for twenty-four hours, then clean it there is always a fourt part of lime added to the falts. I have dif covered that it is ufed in the fame way i this country. I know no obje&ion to it but that of its being againft law. Cor, Sea. I. ON BLEACHING. 217 Cor. 9. Lime-water, with a grain and a half of pearl afhes added to each ounce, hurts cloth but very little, and whitens very much. This is a mighty cheap compofi- tion, and therefore deferves the confidera- tion of bleachers. Cor. 10. The effects of thefe different bleaching materials on cloth are increafed by heat. They operate ftrtinger when kept in a heat nearly equal to that of the human body, than in the heat of our atmofphere in the fummer : they operate ftill more ftrongly in the heat of boiling water, pro- vided that heat is brought on by degrees. This is eafily accounted for, when we con- fider, that the inteftine motion of fluids is augmented by heat, whereby the impetus or momentum of thofe folvents become ftronger, and confequently their effedts fooner produced. Cor. 11. Thofe materials that whiten fooneft, feem to extract moft out of cloth, and to weaken it moft fpeediiy ; while thofe that whiten flowly, extrad but little from E e cloth, 2 1 8 EXPERIMENTS Part IV. cloth, and therefore do not weaken it, This general rule admits, however, of ma- ny exceptions. Cor. 12. Great plenty of air arifes during the operation of thefe menftruums on cloth. This fhows, that there is fome fubftance, which contains plenty of fixed air, diflblved, and feparated from the cloth. Dr Hales obferved great plenty of air-bubbles arifing from calculi, while they were diffolving m foap-lyes. Cor. 13. Acid and alkaline falts lofe, in the fame proportion, as they operate on cloth, their acid and alkaline tafte, and ap- pear to be Iheathed or deftroyed by a junc- tion with, the fubftance they extradt. Cor. 14. Mufcovy afhes, having the fame proportion of pearl afhes added to them as are ufed in the bleachfield, feem to lofe their corroding quality in a great meafure. The common practice of the bleachfield was fufficient to have taught this. The linen- Sed.l. ON BLEACHING. 219 Knen-bag, through which the lye is /train- ed, will ferve for two years. Cor. 15. Pure fea fait does not whiten cloth, but opens, thins, and weakens it.. Hence kelp afhes, which contain about a fourth part of fea fait, mull have the fame cffedt. This is one reafon, among others, why the Irijh cloth is fo thin and weak, as the kelp afhes are generally ufed by them in the firft buckings. Their moll fkilful bleachers have laid it entirely afide, and ufe only the Cajhub afhes. How the kelp afhes may be freed from the fea fait, I have con- sidered in a former fe&ion. Cor. 16. Wafhing with warm water and foap, and rubbing with the hands, are not capable of taking out all the acid or alkaline falts out of cloth that has been fleeped in them. It is only to be done by alkaline and acid falts. Cor. ij. Cloth boiled in old lye gains confiderably in weight, inftead of lofing. Hence it would appear, that old lye is not E e 2 fo 220 EXPERIMENTS Part IV. fo proper for fteeping, the defign of which is to take out the dirt and dreffing. Cor. 1 8. Cloth regularly watered, and ex- pofed to the influence of the air, lofes con- fiderably of its weight, even though it has been well waftied and rubbed in foap and water. This fhows, that the air, fun, and winds exhale fomething, that wafhing and rubbing cannot take out ; and therefore that the latter can never fupply the place of the former, and be attended with the fame ad- vantage. Cor. 19. Cloth, during the procefs of putrefaction, turns blackifh, throws off a OTeat deal of black matter, and is weaken- ed. Thefe effeds muft depend on the quicknefs and degree of putrefaction . Hence it is long before the putrefa&ion of plain water weakens cloth. Hence great care muft be taken, that no corrupted butter milk fliould be ufed in the bleachfield : A circumftance too little attended to. The fame caution muft be obferved with regard to the time at which the fouring procefs ends $ Se(ft-L ON BLEACHING. 221 ends ' y for immediately to that fucceeds the procefs of putrefaction . Cor, 20. Cajlile foap appears to be a very weak bleaching material, and not to correct the corroding quality of Mufcovy afhes or lime. It may however be attended with other advantages. I find that it keeps the cloth foft. Mr Chryjlie fays, that cloth, when foaped, keeps longer moifl, and is eafier cleaned from the ftain of a dirty foot. Cor. 2 1 . Butter milk feems to have fome \ gentle tendency to whiten cloth when yet brown. To cloth already white it would feem to add fomewhat, and to recover, in fome degree, its ftrength when impaired. By its fermentation the acid particles are dif- engaged, and uniting with the abforbent ; earth left in the cloth, render it foiuble in water. Queer. What effed will the juice of o- fnions, leeks, or celery, have on cloth ? They appear by experiment to have a feentle power in dilfolving the ftone. Queer. 2 22 EXPERIMENTS PartlV. Queer. What effedfc will mell marl have on cloth ? These are all the experiments which I have made with regard to the effeds of different bodies on unbleached cloth. Though few, they are fufficient, I hope, to fettle the genuine effe&s of thefe bodies } to teach the bleacher what he is to chufe, and what to rejecT: ; how to balance fafety and expedition, that his method may not become too expenfive by ftudying only the former, or too dangerous by purfuing too eagerly the latter ; and what is of greater* importance, by what fteps the art is to be advanced. But this is not all. The ufe of j thefe experiments may be rendered far more extenfive. They teach the varied effects of [ various bodies, when applied to one an- , other. They increafe the fcience of nature, and lead us to its true philofophy. They ; heighten our admiration of its great author, SECT. Sea. II. ON BLEACHING. 223 SECT. II. The caufe and effeSls of hard water, and the methods of foftening it. THere is no fubjedl fo often mention- ed, and fo little underftood, as tfie caufe of hardnefs in water : there is no fub- jed: of greater importance to the bleacher, or indeed to general ufe ; there is no fubje£t, of equal moment, that has been lefs conii- dered, in an experimental view, than the prefent ; for it lies, fo far as I know, yet untouched. Thefe confiderations induce me to undertake it. We have hitherto been contented with a fhowy theory, how well founded, the following experiments will make appear, that fea fait, if not the only, was the moll general caufe of hardnefs in water. Even experiments helped to cor- ' roborate this opinion ; but experiments made with materials not well underftood 3 and therefore deceitful. The regular method of proceeding in this inquiry, £i 4 EXPERIMENTS PMW, inquiry, feems this, To try whether we can foften hard water, by mixing different ma- terials with it, or treating it in different ways ; than to endeavour to harden foft wa- ter; and, laftly, from thefe experiments, and from others, to difcover the true caufe of the hardnefs in water. It is neceffary to define oiir terms; Water is generally underftood to be hard, when foap, agitated in it with the hand, does not raife a froth or lather on the furface, nor diffolves equally through the water, but curdles, or feparates into a thicker and thin- ner part ; the former of which mounts to the furface, and there remains like a white oil, while the water continues tranfparent below. Hard water has other diftinguim- ing marks j fuch as, not foftening peafe that are boiled in it ; boiling fifh better than foft water ; extracting lefs ftrength out of malt in brewing ; preferving the colour of greens boiled in it, better than foft water ; and not taking the dirt out of foul linen fo well when warned in it. Thefe I think too vague and undetermined to be taken as ftandards for experiment, Se6l.IL ON BLEACHING. 225 experiment. The curdling of foap I fhall then make my fixed point ; on one fide of whieh the foft waters lie, and on the other the hard. We fhall call this the curdling point. This ftandard of hard and foft water I is more certain than any of thofe commonly known 5 and has the advantage of being un- derftood by every body. Our experiments will furnifh us with a fubflance which fhows . the hardnefs of water long before foap can difcover it 5 but not more certainly. We fhall make the proper ufe of it afterwards $ and follow, at prefent, the common ftand- ard of hard and foft waters. The hard wa- ter ufed in the following experiments, was taken in July from a well when it was low. The water which flows from the pipes difiblves foap eafily and equally 3 but this water curdles it diredtly, and in half a minute the foap rifes to the furface. In the former water many air-bubbles arife on the furface, during the agitation, and remain for a long time ; but in the latter few are to be feen, and thofe immedi- ately difappear. In the former of. tart. p. d> makes no ladtefcency or milky colour ; F f but 226 E X P ERIMENTS Part IV; but it does in the latter. The foft water was fpecifically lighter than the hard water ; for a piece of glafs, that weighed in the for- mer 3 dr. i gr. weighed in the latter half a grain lef§. To difcover how far beyond the curdling point this hard water was 5 the following trial was made. Exp. 84. Three parts of foft water and one of hard were mixed, and diflblved fbap e- qually ; fo did two of the former to one of the latter. Equal parts of the foft and hard broke the foap ; but I obferved through the glafs, that the folution was not quite fo equal as the former. When the foap was mixed with two parts hard to one of foft, the foap arofe; but feemed to feparate with fome difficulty : and the line of feparation was not fo diftindt as in the following mixtures, nor the liquor below fo clear. When it had ftood half an hom T I mixed the whole together with a fpoon, and it never after- wards feparated. This laft, then, I mull look on as the firft degree of hard water, and the mixture before it as the laft degree of foft water. When three parts of hard were Sean. ON BLEACHING. 227 were added to one of foft, the curdling was quick, the line of feparation diflind:, and when mixed together, it again feparated. This fliows how far beyond the curdling point lies the hard water, which I ufed in thefe experiments. Fire is generally thought to foften hard water. One is naturally led to think fo, as boiled water has a fofter tafte than cold wa- ter, when made into punch. To afcertain this point, Exp. 85. I tried the hard water when it was fo warm that I could juft hold my hand in it ; but the foap curdled as faft as before. After it had boiled a quarter of an hour, it was ftill the fame. There was no altera- tion, as to this quality, after it had cooled for two hours. Eight Englijh pints were boiled into one ; it feemed then much harder than before. Boiling, then, appears rather to harden this water, than foften it. It is the general opinion, that all waters are foftened by putrefaction, and that flag- F f 2 nation 228 EXPERIMENTS PartlV. nation and expofition to heat are attended with a degree of it. That I might bring this opinion to the teft of fa<5t, Exp. 86. July i. I expofed 4 Englijh pints of this hard water in an earthen veffel near a conftant kitchen-fire. July 14. Still fweet and hard. 24. Still the fame, and continued fo till it was thrown out, Nov. 11. as incapable of corruption. At that time it was reduced to the half ; and, in- flead of being fofter, was twice as hard as at firft , for it required twice its quantity of foft water to make it break foap. When I faw that this water had no appear- ance of becoming putrid, I put, July 24. into the fame quantity of the fame water, in an- other pot, a large handful of dung to haften its putrefaction. The water had a gentle corrupted fmell for two or three days ; but after that, became fweet, and continued fo, as likewife hard, on the 1 ith of November when it was thrown out. That Se6t.II. ON BLEACHING. 229 That I might overcome this antifeptic quality in hard water, Exp. 87. Nov. 11. Into a quantity of this water I put fome flefh, and into the fame quantity I put the fame quantity of fifh. Dec. 10. Both waters were very putrid. The water in which the fifh had been, was now foft ; that with the flefh was ftill hard, though a fmall degree of heat made it break the foap too. By another experiment I found, that hard water, putrified by the affifhmce of flefh, became entirely foft. Hence we learn, that putrefaction foftens hard water; and every tendency towards that procefs muft have a proportionate de- gree of that eflfeft. But hard waters ap- pear to refift that change very powerfully. It is generally thought, that hard water filtered through fand becomes foft. I was of the fame opinion *, and had not trufted to theory alone for it. But being profeffedly f Vid. Dunfe Spaw, feftion on water. engaged 230 EXPERIMENTS Part IV. engaged in this purfuit, and having made the experiment more exactly, and carried it farther than what I had done before, I find that this efledt of fand is limited. Exp. 88, A quantity of fea fand was well wafhed with foft water, each parcel three times, and then put into two cafks that were fet above one another. There was a hole in the centre of the bottom of the up- per calk, by which the water was to pafs into the lower ; and a hole in the under part of the latter, by which the water was to iifue through a pen. When the fand was wet with water, I obferved it decreafed con- fiderably in its volume. This remarkable property of fand, which arifes from a clofer difpofition of its particles by the water as it flows in, is wifely defigned, by the author of nature, to anfwer feveral valuable ends. That I might wafh out all the falts or folu- ble parts from the fand, foft water was fil- tered through it. The water came off hard for two days ; but after that became foft. The hard water was then paffed through the fand, and it came off entirely foft 5 nay more Sed.IL ON BLEACHING- 231 more fo than the town-well water 3 as it feemed to diflolve foap better, when equal parts of it and hard water were mixed, than the town-well water had done in the fame proportion. It appeared fofter from the fol- lowing trial. Three parts of the filtered hard water were mixed with one part hard water ; the town- well water was mixed in the fame proportion. 01. tart. p. d. pro- duced a lactefcency in the latter, but not in the former : but when there were two parts of hard water to three of filtered, a ladle- fcency juft began to appear. But how cautious ought we to be in drawing general conclufions from the apparent fuccefs of an experiment ! The water, running through a quill in a conftant ftream, continued foft for twenty-four hours ; but after that it turned hard, and remained fo. This is eafily accounted for. The fub- ftance, whatever it is, which makes water hard, finds great difficulty in paffing through the interftices of the fand, but is not alto- gether flopped. Hence, by degrees, it is wafhed down by the water, and lies ready to 232 EXPERIMENTS Part IV. to impregnate the foft water which is ifluing through the quill, while its place is fupplied by that immediately above it j and fo on in a continual fucceffion. Thus the water muft after a certain time become hard. From this experiment we may conclude, that foft fprings at leaffc are not fupplied by the fea, as fea- water is hard. This method of filtration may ftill be very proper to free impure waters of the filth they contain, or of their earthy and oleaginous particles, and clarify them, The water before it was filtered, was not only hard, but had a bad tafte. Its tafte after filtration was quite altered : it was naufeous before, but had a faline fweetnefs, after. I have heard, that great quantities, of chalk thrown into wells of hard water made it foft. With this view I tried the following experiment. Exp.Sg. Powder of chalk, mixed with hard water, did not foften it. When boil- ed for a quarter of an hour in hard water, and Se6t.IL ON BLEACHING. 233 and allowed to fubfide, the clear liquor was no fofter than before. It does not therefore foften water, by any change that it makes on the water from an addition of its fub- ftance : but if it has that effedt, it mull a£t as a filter. This appears to be its method of afting : for hard water filtered through a height of chalk of two inches, came off fo foft, that it broke foap \ but oL tart. p. d. produced a laftefcency, in three parts of it mixed with one part hard water. The water filtered through the chalk fo flowly, that I fhould be afraid of its not allowing the water to pafs in any quantity, if the fpring be in the bottom of the well. This was the cafe, as I am told, in a well where this experiment had been tried ; for, afterwards, in dry weather it was always fo low, that they could get no water out of it. Exp. 90. Some hard water was clarified, by having the white of an egg beat up with it, and afterwards boiled. The foap broke pretty well at firft in it but, on Handing G g fome 234 EXPERIMENTS Part IV, fome feconds, it curdled, and rofe to the furface. Lime was tried to foften hard water, and not without fome hopes of fuccefs : for as it is thought a great corrector of the mu- riatic acrimony in the blood, it might have the fame effe£t on the muriatic falts, the fuppofed caufe of the hardnefs of water. Exp. 9 1 . Lime was mixed with hard wa- ter, but it was not foftened by being made into lime-water. The fame lime-water ftood till the calcarious particles were all evaporated, but ftill the water preferved its natural hardnefs. We {hall fee prefently that the real effe& of lime is very different from the imagined one. Exp. 92. It is generally thought, that fern foftens water ; and it is often ufed with that defign : but infufing fome of that vegetable in warm hard water, and letting it ftahd all night, I could not difcover any fuch e£Fe£t The falts in it, though they do not {often the water, may perhaps quicken the eftedt of Sedfc.II. ON BLEACHING. 235 of water, when It is to operate as a men- itruum, to loofen the oils of vegetables : for it is in the fteeping of lint that fern is ufed. Let us try what experiments made on no previous theory will produce. Exp. 93. The extract of bark, of gen- tian, and of centaury, appeared, at my firft trial, to have a power of foftening hard water ; but, on repeating the experiment, I found, that the dark colour of the folu- tions, or the mixture of fome alkaline falts with thefe extracts, which fometimes hap- pens, had mifled me. Nor did I fucceed better in foftening hard water with the ex- trad: of wormwood, of black hellebore, of chamemile, or of logwood ; with rhubarb, Bohea tea, lintfeed, oak bark, gum Arabic, or gum ammoniac. Exp. 94. A folution was made of 2 fcrup. of blue pearl alhes In 2 oz. of foft water. Sixty drops of this folution, mixed with a fpoonful of hard water, difiblved foap with- out curdling, A hundred drops of a folu- G g 2 tion, 236 EXPERIMENTS PartlV. tion, that contained juft 5 gr. of blue pearl afhes, made four fpoonfuls of hard water foft ; but the foap curdled on the addition of another fpoonful. We have then found a foftener of hard water where it was not expected. This experiment led me to try the following. Exp. 95. Twenty drops of the fpirit of harts-horn foftened two fpoonfuls of hard water. The fame number of drops, mixed with the fame quantity of hard water, and allowed to ftand for two or three days till the fmell of the fpirit was gone, broke foap as well as with the recent addition. That I might find out the precife quantity of dry volatile fait, I difiblved 2 gr. in half a fpoon- ful of hard water, which broke foap well ; but when I added another half-fpoonful, it was with fome difficulty that it broke foap : but after it had done it, there was no fepa- ration. Thus we have found two fub- fiances, the fixed and volatile falts, which have a remarkable effed: in foftening hard waters. How far thefe may be applied with fafety Se6t.II. ON BLEACHING. 237 fafety to the common ufes of life, we fhall afterwards confider. Let us next endeavour to difcover what fubftances make water hard. I could not procure diftilled or rain water in quantity enough to ferve me in all the following ex- periments ; but the moft important were performed with the latter. We fhall begin with the mineral fubftances. Exp. 96. A large key was infufed in foft water for a day : it made the water yellow, and gave it a ftrong chalybeate tafte, but did not harden it. Neither did a red-hot iron quenched feveral times in foft water. Cop- per infufed in foft water for two days, gave it a mineral tafte ; but did not change it in- to hard water. Sea fait is commonly thought, if not the only, at leaft the moft general caufe of the hardnefs in water. It was natural to think fo, when we found, that common fea fait curdled foap difiblved in water, and consi- dered how general an ingredient it is in all waters. 2 3 § EXPERIMENTS Part IV. waters. But the following experiments wili /how us, that this is not the effedt of fea Mt y but of the impurities mixed with it. The fea fait, which I ufed, is a particular kind that is only made on Sunday ; and therefore called $unday-falt y or great fait, from the largenefs of its grains. It cryftal- lifes at a time when the fire is low, and the fea water not altogether evaporated, as it is in the common way of making fait* It contains lefs of the bittern than the com- mon fea fait, and has therefore a particular fweetnefs. It is the moll: proper for the table and for experiments, Exp. 97* A grain of pure fea fait was dif- folved in 4 fpoonfuls of rain-water. This folution diffolved foap well, and did not turn Iadlefccnt with ol. tart. p. d. Some drops of a folution of quickfilver in aq. for- th made a great ladtefcency in it ; this lac- tefcency was juft perceptible when the fo- lution of the fea fait was diluted with fixteen times its quantity of water. This folu- tion of quickfilver, then, does not difcover hard waters 3 it only difcovers fea fait in wa- ter ; Sea. II. ON BLEACHING. 239 ter ; and that when in a very fmall propor- tion, 1 gr„ in 3 Englijh pints of water. Exp. 98. A fpoonful of rain-water, with 5 gr. of pure fea fait diffolved in it, conti- nued loft. With 6 gr. there appeared a little curdling, but a little more agitation diflblved the foap. This curdling feems to be owing to fome remainder of the bittern ; for 2 gr. of common fea fait made water as hard as fhefe 6 gr. had done. The bittern has this quality fo ftrong, that a fourth part of a grain of the bittern fait hardens a fpoon- ful of rain-water. The ipirit of fea fait fa- turated with an alkaline fait, does not hard- en water. The proof ftill becomes fir on g- er, when a fmall laciefcency appears on dropping oL tart. p. d. into a folution of 5 gr. of pure fea fait in a fpoonful of rain-water. From thefe fads it appears, that pure fea fait has no hardening quality, and that the bittern has it in a very ftrong degree. The hardnefs of waters can never be owing to the former fait, as the tafte can difcover a final ler admixture of it than what would be 240 EXPERIMENTS PartIV, neceffary to have that effect, if it ever has any fuch. Thus pure and impure fea falts appear, by experiment, to have very different effedts on bodies. I am afraid this has not been fufficiently attended to and the effects of the bittern have often, unjuftly, been attri- buted to fea fait. I have difcovered, lince I made the preceding experiment, that Lemery has long ago made the proper dif- tin&ion betwixt thefe falts *. The common Epfom fait, fold in the fhops, is the bittern or fecond kind of fait in fea water. Exp. 99. Five grains of Epfom fait hard- ened 2 fpoonfuls of foft water fo much, that it required to be diluted in 16 fpoon- fuls, before it began to break foap. A great ladtefcency happened betwixt this folution and ol. tart. p. d. Exp. 100. Alum renders foft water very Cours de chymie, p. 307. hard ; Se6l.IL ON BLEACHING. 241 hard j fo that 5 gr. required 20 fpoonfuls of foft water before it would break foap. 01. tart. p. d. made a ladtefcency. Exp. 101. Salt of fteel hardens water. I was obliged to dilute 10 gr. in 45 fpoonfuls of foft water to make it break foap. Eve- ry one knows, that alkaline falts render a folution of this fait turbid and green. Exp. 102. Blue vitriol or fait of copper hardens water fo much, that 5 gr. required to be diluted in 3 5 fpoonfuls of foft water to make it break foap. Alkaline falts turn a folution of this turbid and blue. Exp. 103. Vitriolated tartar got from the apothecary's fliop hardened water ; but finding that it had a ftrong acid tafte, I made fome, by dropping 40 drops of fpi- rit of vitriol into a folution of fait of tartar. When the faturation was fully completed, I put the whole into two fpoonfuls of foft water, and it dilfolved foap very well. No ladefcency. H h Exp. 242 EXPERIMENTS PartIV* Exp. 104. Five grains of the fugar of lead hardened water. When diluted in 24 fpoon- fuls, it began to diffolve foap. The alkaline folution made a laftefcency in it. Exp. 105. Crude ammoniac fait, borax, fal prunel, fal polychreft, gum ammoniac, chamemiie flowers, oak bark, Peruvian bark, did not harden water. Nor did oil of tartar produce a ladtefcency in their fo- lutions. Exp. 106. Five grains of cream of tartar hardened foft water ; but when diluted in fix fpoonfuls, it dilfolved foap. No ladle- fcency. Exp. 107. Five grains of fait of amber made water fo hard, that I was obliged to dilute it with 50 fpoonfuls before it would break foap. No laftefcency. Exp. 108. Twelve drops of fpirit of vi- triol required eight fpoonfuls before it would diffolve foap. One drop of oil of vitriol re- quired to be diluted in fix fpoonfuls, the fame » Sedt.II. ON BLEACHING. 243 fame quantity of fpirit of fea fait in five fpoonfuls, the fame of nitre in three fpoon- fuls of foft water, before foap could be e- qually diffolved. A tea-fpoonful of vinegar required eight large fpoonfuls of foft water to make it break foap. The alkaline folu- tion raifes an effervefcence, though it does not make a ladlefcency with thefe acids. Exp. 109. Some powder of chalk was well mixed with cold foft water : it was poured off after the chalk fettled, and dif- folved foap. Soft water boiled with chalk for half an hour, was not hardened by it. Some clay wrought for fome time in water, and allowed to fubfide, did not harden it. Lime renders water remarkably hard. Exp. no. Lime-water that was made with foft water, and had flood for three or four days over a great quantity of lime, which had before afforded fome pints of lime-water, curdled foap at once, and be- came milky with the alkaline folution. One fpoonful of this lime-water required fix fpoonfuls of foft water before it broke foap. H h 2 Ten 244 E X P E R I M E N T S Part IV. Ten ounces of lime-water was boiled into two, but it diffolved foap no better than be- fore. The fame lime-water, when it had become vapid with Handing, broke foap as well as foft water. The hardnefs of lime- water appears plainly to be owing to the fo- luble parts of the lime ; and the more wa- ter contains of thefe, it mull be the harder. W e cannot know from this the real quanti- ty of thefe particles contained in the water ; bat we may know the proportionate quan- tity 3 and of courfe the comparative ftrength of different lime-waters. Let us, then, try to determine, by this teft, an interefting queftion, Whether double or triple lime- water is ftronger than fingle ? Exp. 1 1 1 . I made fome lime-water ; in half an hour I poured moft of that fingle lime-water upon frefh lime ; about the fame time after I poured moft of that double lime-water upon frefh quick-lime ; and fo made a triple lime-water. When they had all Hood about two hours, a fpoonful of the fingle lime-water required to be diluted with 9 fpoonfuls of foft water, before it would Sea. II. ON BLEACHING. 245 would break foap ; the double required 12, and the triple 15. The times and force of agitation were, as near as I could make them, the fame. I poured the triplp lime-water again upon quick-lime. The other lime- waters were poured from the lime into open glaifes. An hour and an half afterwards the fingle lime-water required 9 fpoonfuls, the double 1 1, the triple 13, and the qua- druple 17. This laft experiment was made at twelve at night. Next morning- the whole four lime-waters, having flood all night in open glafles, required but 9 fpoon- fuls, although the quadruple lime-water had flood over its lime all the night. This experiment agrees exactly with what I had formerly difcovered by weighing their fpe- cific gravities. A piece of glafs weighed 2 dr. 23 gr. in town-well water ; in lingle ftone-lime water it loft a grain, and in triple a quarter of a grain more. This fhowed, the fpecific gravity of the triple lime-water was greater than that of the lingle, by a fourth of the difference be- twixt the laft and plain water. The lime- waters in this laft experiment had flood for two 246 EXPERIMENTS PartIV, two hours, till they were entirely clear. I repeated the former experiment again, and I ftrained the waters, after they had ftood an hour, through brown paper. The fingle lime-water required 8 fpoonfuls of foft water before it broke foap, the double 9, and the triple 11. I was refolved to fee how far it would go, and made a qua- druple 5 but, finding it took no more than the laft, I defifted. That I might difcover how long thefe different lime-waters would preferve a dif- ference in ftrength, if kept in clofe bottles, Exp. 112. I made fingle, double, and triple lime-waters, ftirred them frequently for four hours, and then ftrained them. The fingle required 1 5 fpoonfuls of foft wa- ter, the double 18, and the triple 20, be- fore they broke foap. They were bottled, corked, and waxed over. After they had flood 10 days, they required the fame quan- tity as before to foften them. When kept fome days longer, the fingle was flill of the I Setf.II. ON BLEACHING. 247 the fame ftrength, but the triple required only 1 8 Ipoonfuls of foft water. As it may be objected to thefe experi- ments, That the water had not ftood a fuf- ficient time over the lime, nor had they been frequently mixed together, Exp. 113. I made two different quanti- ties of lime-waters, with two parcels of the fame quick-lime. I tried one of the lime- waters in the above-mentioned way, after it had flood without ftirring for two hours. The other ftood over the lime twenty-four hours, and was frequently ftirred. They were equally hard, and therefore equally ftrong. Lime-water then made with un- flaked lime, need ftand no longer than it is clear. The conclufion, then, from thefe expe- riments, is, that lime-waters made with dif- ferent lime, differ very much from one an- other ; that double lime-water is flronger than iingle, and triple than double ; and that they retain their different ftrengths, if kept 248 EXPERIMENTS Part IV. kept from the influence of the external air ; but if expofed to it, in open veflels, in a few hours become of equal flirength. To try what efFedt alkaline falts had as to the foftening of lime-water, Exp. 114. I poured 011 quick-lime fome water, in which the fourth part, in propor- tion to the lime, of blue pearl afhes had been diffolved. The water had a fharp pungent tafte, and feemed to j3e about the hardnefs of the hard water, which, though hard, is much fofter than lime-water. The foftening power of the alkaline falts, appears yet better from the following expe- riment. One ounce of potafhes diflblved in two gills of water, and poured on an ounce of quick-lime, produced a very cau- ftic liquor, which broke foap, but not fpee- dily. Lime-water is foftened by an addition of alkaline falts. From this experiment we may fee the reafon, why the foap mixed with the lye, which is a compofition of lime and alkaline falts, is not curdled. A Sed.IL ON BLEACHING. 249 A table of the comparative power of bodies with regard to foftening and hardening of water. Comparative foftening powers. Filtration through fand foftens in propor- tion to the length of its courfe. Putrefa&ion foftens in proportion to its de- gree. Volatile fait of hartfhorn — — 1 Fixed alkaline falts, though not of the ftrongeft kind ■ 2 Comparative hardening powers. Epfom fait 3 Alum - — - — 4 Salt of fteel 44 Blue vitriol • 7 Sugar of lead ■ 5 Cream of tartar ■ It Salt of amber — — 10 Oil of vitriol — — 18 Spirit of fea fait 1 5 Spirit of nitre 9 The foluble part of lime 45 I i In 250 EXPERIMENTS Part IV. In computing the hardening power of thefe acid fpirits, I have allowed 3 drops to be equal to a grain > which may ferve very well in a general way of computation. But when we confider, that there is but a part of thefe fpirits real acid, and that thofe which I ufed had been negligently kept, we fhall fee reafon for attributing a very ftrong hardening power to the real acid falts of thefe liquors. By the trials which I have made, there appears to be but 1 gr. of the foluble part of lime in 5 oz. of lime-water, which I reckon equal to 8 fpoonfuls 5 and one fpoonful was found to require 6 fpoon- fuls of loft water to make it break foap. It mull be obferved, that all thefe arti- ficial hard waters, except thofe made fo with acids, were rendered turbid or ladte- fcent with alkaline falts. This will be found a general rule, That where-ever foap is curdled, alkaline falts produce a change in the colour and purity of the water , becaule both effeds depend on the fame caufe. Hence arifes a new ftandard to help us to judge of the degree of hardnefs in waters. Let us Sea. II. ON BLEACHING. 251 us inquire at what time this change of co- lour arifes 5 it may, perhaps, difcover a lefs degree of hardnefs in water than foap does. Exp. 1 15. A mixture was made of equal parts of hard and foft water. This we found before not capable of curdling foap, and, therefore, called it the laft degree of foft water. This foft water, on dropping fome of the folution of pearl afhes into it, turned as white as the hard water did with the fame folution. When two parts of foft water and one of hard were mixed, a ladtefcency arofe with the folution, but weaker than in the laft. When three parts of foft were mixed with one of hard, a very difcernible altera- tion of colour ftill happened. Thus we fee, alkaline falts difcover a much lefs de- gree of hardnefs in water, than what foap does. Let us therefore c/all this degree of hardnefs in waters, whereby they are made to change their colour with alkaline falts, the laSlefcent point. We are now on a better footing than what we were when we fet out. We have I i 2 gained a 5 2 EXPERIMENTS PartIV, gained two fixed points in hard waters, that will allow of companion. We may now divide all waters, with regard to this quali- ty of hardnefs, into three forts. The firft are thofe which neither change with alka- line falts, nor curdle foap ; the fecond, thofe which lofe their tranfparency with thefe falts, but in which foap is not curdled ; the third fort are thofe where both effects hap- pen. The firft clafs are the fofteft of all waters, and the fitteft for moft ufes in life ; the fecond clafs, at leaft the firft degrees of that clafs, may do tolerably well in the com- mon houfehold-affairs, though not in the bleachfield; but the third fort I condemn as hurtful, and improper in almoft all cafes* The water which iffues from the pipes of Edinburgh wells, is in the firft clafs : for it not only breaks foap well, and retains its tranfparency when fait of tartar is mixed with it ; but likewife fhow r s no ladtefcency, when a folution of quickfilver in aqua fortis is dropped in it. By this laft we difcover, that if it contains any fea fait, it muft be in a lefs proportion than one grain to three Seft.II. ON BLEACHING. 253 Englijh pints ; too inconliderable a quantity to be taken notice of. The foregoing obfervation leads us like- wife to another very material conclufion ; which is, that the curdling of the foap is brought about by the alkaline falts, and not the oil : which two bodies, with a little lime and fea fait, make up the compofitioti of hard foap. The fea fait has not that ef- fect, as we proved before ; and the lime is in fuch a fmall proportion, and mixed with alkaline falts, which we juft now found foftened it, that it cannot be the caufe of the curdling of foap. We have found, that neither natural nor artificial waters ever curdle foap, without having their compoli- tion altered, or vifibly affe&ed by alkaline falts : it therefore follows, that the alkaline part of the foap is the part on which thefe hard waters work. Accounting for the lac- tefcency with fait of tartar, is accounting then for the operation of foap. It is no wonder that hard waters produce their ef- fect fomewhat later on foao, as it is defend- ed by the oil from their operation longer than 254 EXPERIMENTS PartlVi than the naked falts. As foap is a more compounded body than the falts, the cir- cumftances refulting from a mixture of hard water with each muft be very different. We have difcovered, in thefe experi- ments, three different caufes of hard wa- ter; quick-lime, acids, and neutral falts. This property in lime fhall be examined by itfelf. Acid falts, fuch as the oil and fpirit of vitriol, the fpirit of fea fait, and that of nitre, vinegar, Cream of tartar, and fait of amber, hardened water remarkably. Why they ftiould do fo, is eafily explained. The alkaline falts having a ftronger tendency to the acid than to oil, quit the latter, and adhere to the former. Hence the artificial compofition of foap is deftroyed, and the oily part, feparated from the alkaline, floats like clouds, andatlaft, by its fpecific light- nefs, rifes to the furface. The ftronger the acid is, every thing elfe equal, the harder muft it make the water. Hence the mine- ral acids, considering the great proportion of real acid in them, have the ftrongeff ef- fects : but thefe can feldom or never im- pregnate Scft.II. ON BLEACHING. 255 pregnate natural waters, becaufe abforbent particles are found almoft every where; which would diredtly join the acids, and re- duce them to neutral falts. In fad: no acid water has yet been difcovered. This leads us to confider thefe neutral falts as the ge- neral caufe of hardnefs in water. When I look back on thefe experiments, I cannot but obferve one remarkable fad: ; which is, that none of the more perfedl neutral falts, compounded of an acid and alkaline bafe, render water hard ; but that all the imperfect falts, compounded of an acid and abforbent earth, or a metal, have this effect on water. Epfom and alum falts have an abforbent earth for a bafe ; fait of fteel, fugar of lead, and fait of copper, a metallic one. It is a fa£t known to all chy- mifts, that when alkaline falts are poured on a folution of the imperfedt falts, the a- cid quits the abforbent earth or metal, and joins the falts ; becaufe the power of attrac- tion betwixt the acid and falts is ftronger than betwixt the acid and earth or metal. But when thefe alkaline falts are added to the fo- lution 256 EXPERIMENTS PartlV. lution of the more perfect falts, no change can happen; becaufe the alkaline falts, to which they are already united, attradl the acid as ftrongly as thofe that are now added. It is the fame thing then with refpedt to the al- kaline falts, whether the acid is or is not joined to a metal or abforbent earth, fince it fo eafily leaves them. But the effedts which follow will be different : for, in the former cafe, the liquor muft lofe its tranf- parency, at leaft for fome time, on account of the deferted particles which float in the liquor ; but in the latter no fuch effedt can happen, and the liquor mqft continue lim- pid. Hence arifes already a great preemp- tion, that thefe imperfect falts are the com- mon caufe of the hardnefs in waters, fince the appearances in both cafes correfpond fo exadtly : for a curdling of foap, a ladle^ fcency, and precipitation, are obferved in both natural and artificial hard waters. But it muft feldom happen, that the hardnefs of waters is owing to a neutral fait, compo- fed of an acid and a metallic bafe ; confider-r ing Sea. II. ON BLEACHING. 257 ing how much oftener the acid mull be joined to an abforbent earth. The former does fometimes happen : for the Hartfield water is very hard ; and experiments fhow, that it contains a fait of fteel, and no other. When this is the cafe, the water becomes a mineral water, and will foon difcover it- felf by its mineral effects . In all hard wa- ters, then, excepting the mineral, we may prefume, that there is an imperfedl neutral fait. This caufe of hardnefs in waters accounts for the power which alkaline fixed and vo- latile falts have of foftening thefe hard wa- ters. Thefe two bodies unite themfelves with the acid, and throw off the abforbent earth : the fixed falts conftitute with the a- cid a perfect fait ; which fpecies of falts, as we already difcovered, has no power of hardening water 5 and therefore the water becomes foft. The volatile alkaline uniting with the acid conftitutes an ammoniacal fait, or one like it 5 which we found like- wife not to harden water ; and therefore the hard water becomes foft. The water is K k rendered 258 EXPERIMENTS PartlV. rendered by that change on the falts more healthful $ which we were not fure of when the fadt was firft difcovered. Let us try how far experiment will fup- port this theory of hard waters : for I can allow it to be as yet nothing but a theory, though a plaufible one ; fince it arifes only from a fimilitude of effe&s betwixt natural and artificial hard waters. If this theory be true, we fhall be able to exhibit to the eye thefe hardening falts, or at leaft fome part of them ; by which we may difcover, that the other part has been once prefent. Let us fee what evaporation will give us. Exp. 1 16. Four Englijh pints of this hard water were evaporated to drinefs, and left 26 gr. of a brown powder, which had a pungent faline tafte, and liquified in the air. This powder effervefced with both vegetable and mineral acids 5 but it effervefced like- wife with a folution of alkaline falts. It muft therefore be a compofition of both a- cid and alkaline falts, or abforbent earths ; the latter of which feem to prevail, as the Se6l.IL ON BLEACHING. 259 powder turned the fyrup of violets green. Brown paper dipped in a folution of it, and dried, burnt like a nitrous match. Six grains and a half of the powder diffolved in a pint of foft water, made it fo hard, that it would fcarcely diflblve foap. In this re- fiduum, then, we have difcovered the hard- ening caufe , but it appears, that about the half of it has been difpelled by the evapora- tion. It is probable, that this volatile part is an acid, as the refiduum feems to partake moffc of a contrary nature. Let us fee whether we cannot make this acid more fixed and more vifible, by join- ing it to an alkaline bafe. Exp. 117. Into four and a half gills of hard water, was dropped ol. tart. p. d. as long as any la£tefcency was made by it. Du- ring the addition of the alkaline fait, I ob- ferved through the glafs a very great in- teftine motion in the liquor : fome air-bub- bles, though but very few, arofe , and the clouds difperfed themfelves through the whole with a confiderable motion. But no K k 2 fuch 2 6o EXPERIMENTS PartlV. fuch effedt happened when I dropped the fame folution into foft water. Here then is a plain and diftin£t inteftine motion or ef- fervefcence. The liquor, having ftood all night, appeared tranfparent in the morning, and the bottom of the glafs was covered with a whitifh powder. The water now broke foap. When the whole was fhaked, it turned white ; which fhows the milky colour is owing to this powder. The liquor was ffcrained through brown paper, and I had five grains and a half of white powder. To be fure that this precipitation did not ever happen in foft waters, and that it was no part of the alkaline fait, I dropped the fame quantity of gL tart. p. d. into the fame quantity of foft water ; but no precipitation followed. This powder, when mixed with foft water, did not harden it ; when kept in a firong kitchen-fire for two hours, it was reduced to good quick-lime. That I might difcover the contents of the hard water, after the addition of alkaline falts. Exp. Seft.IL ON BLEACHING. 261 Exp. 118. Three chopins of hard water were treated in the fame way, and evapora- ted to 2 oz. of a red liquor. The firft fait that feparated from the liquor weighed 15 gr. It turned fyrup of violets green, and effervefced with fpirit of vitriol ; marks of its being alkaline. More alkaline falts had been added than what were neceffary. The next cryftallifation afforded me a fcruple of a fait, which, though it feemed to be of an alkaline caft, approached much nearer to the neutral ftate than the former, gave ftrong marks of a nitrous fait, and afforded me great hopes from the next cryftallifation. It fucceeded accordingly. In a night's time I had half a drachm of fine white cryftals, fome of them ah half-inch in length, and exaftly like the regular cryftals of nitre. They had a bitter cooling tafte 5 when join- ed to oil of vitriol, emitted ftrong acid fumes, and corroded filver ; when vinegar was poured in them, a few air-bubbles a- rofe : but thefe feemed plainly to be ow- ing to the alkaline liquor round them j for the cryftals lay for fome time, after the inteftine motion ceafed, undiffolved at the 262 EXPERIMENTS PartIV, the bottom of the glafs : when brown paper was dipped in a folution of them, it burnt, and Iparkled like the fame dipped in a folu- tion of faltpetre. Thefe charadteriftical marks, with its effects of turning flefh red when boiled in the water, are fufficient to prove it to be a real faltpetre -> for thefe are the properties of that fait, and belong to no other. The liquor remaining was of a dark colour, and tailed like a folution of fea fait. The earth in this hard water we demon- ftrated before to be of the calcarious kind, and convertible into lime. We have at pre- fent demonftrated the acid of this hard wa- ter to be that of nitre. The chymifts deny that fuch an acid exifts in \ nature, and af- firm, that it is made from the vitriolic and an inflammable principle conjoined : but here we have found it prefent, and have helped to volatilize it. Hoffman denies the exiftence of nitrous waters, and fays, that an inflammable foffil nitre is no where to be found *. Here, indeed, the nitre was in * De element, aq. mineral. &c. par. 39. an Sed.II. ON BLEACHING. 263 an imperfed ftate, but ftill inflammable. There is great probability, that a real nitre may fometimes exift in the bowels of the earth, fince the alkaline bafe often appears in waters. The experiments performed on mineral waters at Paris before the Royal a- cademy of fciences, demonftrate clearly the exiftence of a nitrous fait *. Since this acid feems of fo volatile a na- ture, let us try if hard water diftilled gives any fign of containing an acid. Exp. 119. I diftilled fome hard water. The diftilled water (howed no effervefcence with alkaline falts, but turned the fyrup of violets into a light red. Common foft wa- ter had no fuch effedt. Here, then, we difcover an acefcent quality in the fteams of hard water, that can rife only from an acid exifting in that water; and as the water gives no marks of acidity, we muft con- clude, that, by adhering to an abforbent bafe, it is converted to a neutral fait. * Vid. Du Clos. There 264 EXPERIMENTS Part IV. There cannot be a ftronger proof that waters owe their hardnefs to fuch a fait, than to fhow that fimilar artificial compolitions have this effect. Such falts as thefe muft be continually produced by nature ; as an acid and different abforbent earths are almoft every where to be found. Exp. 1 20. Four grains of the earthy refi- duum of white pearl afhes were faturated with the fpirit of vitriol, and half an ounce of water added. Two parts of this faline liquor added to three of the rain-water, would not break foap. Exp. 121. The fame quantity of chalk was managed the fame way. Two parts of this to three of rain-water made the foap rife to the furface. Exp. 122- Six drops of fpirit of nitre, faturated with chalk, made foft water fo hard, that it required 60 fpoonfuls before it would break foap. Exp. 123. The fame quantity of fpirit of fea Seft.IL ON BLEACHING. 265 fea fait faturated the fame way, required 80 Ipoonfuls. Exp. 124. The powder which was preci- pitated by ol. tart. p. d. from three Englijh pints of hard water, being faturated with oil of vitriol, made the fame quantity of foft ■ water nearly as hard as what the former had been \ for equal parts of this artificial hard water mixed with foft, diffolved foap, though with fome difficulty. The quantity of acid added was 66 drops. There was a great part of this earthy fubftance, which the acid could not diffolve. These different experiments feem to have clearly made out, that the hardnefs in this water is owing to an imperfed: fait, compounded of the nitrous acid and an ab- forbent bafe. It is probable, that moft wa- ters, excepting the mineral, owe their hard- nefs to the fame caufe - y efpecially when we confider that it is obferved of them all, that they give flefh boiled in them a red co- lour. I have examined many different hard waters in different parts of the country, and have always difcovered the acid to be ni- L 1 trouSp 266 EXPERIMENTS Part IV. trous, but the bafe only abforbent, and ne- ver calcarious but in the foregoing. Thus we fee the very ingenious Dr Stephen Hales has come near the true caufe, when he lays, * " That the hardnefs of many waters, and when the linen is waflied with foap. In this cafe, the latent oils and dirt will not be loofened by the foapy menftruum. This is the reafon that hard water will not wafli the dirt out of foul linen. But when the hard w r ater was foftened by the alkaline falts, it waflied as well as the fofteft water. Again, 280 EXPERIMENTS Part IV. Again, whenever hard water is mixed with the lye, it muft turn immediately thick. This difadvantage can be cured, by allowing the lye to ftand for fome time, and drawing off the clear liquor. But there is another which cannot : the acid in the hard water joins the alkaline falts in the lye, reduces them to a neutral ftate, and confequently renders them of no effed in bleaching. But thefe are not the only difadvantages of hard water in the bleachfield. Thefe falts, thrown on the linen along with the water, muft penetrate where-ever the water goes. The fun will foon volatilize the acid part ; but the earthy will be left in the fubftance of the linen, and render it hard and hufky. Nothing but an acid can take that earth out, by reducing it again to a faline ftate. Hence, if more earthy particles are depolit- ed by the watering, than what are carried off by the fouring, the cloth muft not only turn hard, but muft be tore into holes, and rendered ufelefs. In this way I imagine it hardens pot-herbs which are boiled in it. The Sed.II. ON BLEACHING. 281 The more of thefe faline particles are in the water-, the more crufts will be formed in the veffeis in which it is boiled. Hence we find, that all hard waters depofit much tar- tarine fubftance, while no foft water is found to have any fuch effe£t. The Comb water, as mentioned by Dr Hales, is obfer- ved to be fofter, and to wafh linen with a lefs quantity of foap, than the 'Thames water ; while it left no incruftations in the coffee- houfe boiler, that had been in conftant ufe for fourteen years. Bleachers know very well how to a- void hard waters of the third clafs ; bi-t ha- ving no criterion for thofe of the fecond, they muft often ufe hard water without knowing it to be fo. I have difcovered a great degree of hardnefs in fome of their waters. A method, then, of detecting the fmalleft degree, muft be of confiderable ufe to them. Alkaline falts enjoy this property, and have already been of fervice in this way. Mr Samuel Hart had pitched on a fpot of grou nd to make a bleachfield ; had examined the fpring by the known methods ; and thought N n it 282 EXPERIMENTS Part IV. it good. But on trying it by this teft, which I had informed him of, he difcover- ed a confiderable degree of hardnefs in it, and fixed his bleachfield on another fpot. As I thought an examination of differ- ent fprings, in this way, would be of ufe in fhowing what is the proportion of hard fprings to foft, I defired that gentleman to examine a variety of them, and give me an account of his trials. As he has done it with great pains and accuracy, I fhall give the account in his own words. two of which " proved like this, but not altogether fo cc hard. The other three, which rofe on the " high grounds, were quite foft, remaining " pure with the falts after many hours " ftandlng. The chief and laft fpring " which I tried on Vogrie and which alfo ci rifes on the high ground through a bed " of white fand, is a fixong run of water, " known by the name of the Carfe well. " This is the fpring I have chofen to fup- cc ply my bleachfield. After mixing the " falts with fome of this water, it continued " quite pure for three days, the time I " kept it in the glafs : and as from this " favourable appearance I had reafon to " think the fpring very foft, I determined, « from other corroborating proofs, to be " farther 286 EXPERIMENTS PartlV. " farther aflured ; for which purpofe I " made two comparative trials with water and ftill fo hard, that it curdled foap. N°6. quite frefh, with a quantity of air-bubbles on the fur- face of the water 3 which {hows a begin- ning change. Dec. 26. N° 6. fmells putrid. N° 8. continues ftill found. From this experiment the following conclufions arife. ijl, This hard water ap- O o 2 pears 202 EXPERIMENTS PartlV, pears to be a ftronger antifeptic than lime- water but not fo ftrong as tar-water. 2dly y Two drachms of pure fea fait, dif- folved in 8 oz. of loft water, increafed con- fiderably * There is a difference in opinion with regard to the an- tifeptic effects of this foluble part of lime, betwixt two gen- tlemen, to whom the world is much indebted for many in- genious and accurate experiments ; I mean Dr Aljhn and Dr Pringle. The former fays, that the (oluble part of lime, or lime-water, Is antifeptic ; the latter, that it is not. When fuch ingenious gentlemen, who realbn and form conclufions from experiment alone, diffei in opinion, it muft be from their viewing things in different circumftances and fixa- tions. I am always apt to conclude in fuch cafes, that both opinions are, in fome meafure, true. It is then worth our labour to difcover by experiment, what difference in, the circumftances of thefe gentlemens experiments gave rife to fuch a difference in their conclufions. I am the more particularly called upon to give my opinion in this queftion, as two letters of mine, which were not defigned to be made public, have been, by a miftake, publifhed in the Phi 'loj (ophi- cal TranJacHons. Exp. i . Dec. 6. I put two haddocks in an earthen pot, which held %\ Englijb pints, and filled it with lime- water. One lb. of beef was put in another pot of the fame bignefs, and filled with lime-water. After they had ftood, well corked, eighteen days, the former was quite fweet, and fmelt like good lime-water ; but the latter had a pu- trified fmell, though not very ftrong. One of the fifli was partly boiled, and partly dreflejd on the gridiron ; and it eat both ways very well, though a little loft, and retaining fomewhat Se&.II. ON BLEACHING. 393 fiderably its feptic power. Two drachms of common fait preferved the fieifh twice as long as the fame quantity- of pure fait. This muft have been owing to the mix- ture fomewhat of the tafte of lime-water. The flefh was a little tainted, and of a whitifh colour, when prepared in the fame way. Frefh lime-water was put on both, the former being poured off. When they had flood four weeks longer, the fifh was quite frefh, and appeared fomewhat fwelled ; but the flefh was very putrid When the fifh was put into boiling water, it dLTolved immediately into a gelly. Lime-water appears, then, to deftroy the cohering principle in fifh. Exp. 2. March 26. I hung about 3 oz. of flefh and a fmall haddock in the open air in the kitchen ; put the fame quan- tities of thefe two fubftances in two different pots filled with common water, ordering the water to be changed every day ; and the fame quantities of the fame fubftances into two pots, fuch as I mentioned in the former experiment. April 2. The fifh and flefh in the air were dried ; the fifh had no bad fmell, but the flefh was tainted : the fifh and flefh in common water frnelt flrong ? the fifh in the lime- water was fweet, but the flefh fmelt as ftrong as that in the common water. Exp. 3. May 18. Into four different glafTes, each of which held 3 gills of 11 me- water, I put four different fub- ftances ; into the fiifl 1 oz. of beef ; into the fecond the fame of lamb ; into the third the fame of mutton ; into the fourth the fame of whiting ; and corked them. 26. The glafs containing the lamb flank much ; the beef and mutton were a little corrupted ; but the fifh quite found. June 2. The 294 EXPERIMENTS Part IV. ture of the bittern with the former ; and fhews, that thefe two falts have very dif- ferent effects. The fifh was ftill fweet, but all the flefh fmelt very ftrong : the lime-wa^er in which the beef was, appeared of a high red colour ; that in which the mutton was, appeared lefs red ; that with the lamb was but gently tinctured ; that with the filh was ftill white. The lamb feemed mod pu- trid. June j. Fifli found. 26. Fifh was putrid. Jug. 6. The filh fmelt more offenfively than any of the former. Would not any one be apt to conclude from thefe three experiments, that lime-water preferved fifh, and not flefh ? I did fo ; but was foon convinced of my error by the fol- lowing experiment. Exp. 4. May 19. Into an earthen pot, holding 3^ EngUJh pints of common water, 1 put 1 - oz. of mutton ; into an* other, holding the fame quantity of lime-water, I put the fame quantity of mutton. 26. The mutton in common water was putrid, but that in the lime-water was not. June 7. Flefh in the lime-water ftill fweet. 26. Still found. Jug. 6. Was a little putrid. It appears, then, from thefe experiments, that lime-wa- ter is antifeptic, with regard to flefh, when ufed in a cer- tain quantity, and when the pieces of flefh are fo fmall that the lime-water can eafily penetrate them ; that lime-wa- ter is antifeptic, with regard to fifh, in a greater degree, probably becaufe it more eafily penetrates fifh, from its lefs firm texture ; and that the difference of thefe two in- genious gentlemens conclufions arofe, probably, from their ufing. in their experiments, different quantities of flefh and lime-water. We Se6t.IL ON BLEACHING. 295 We could eafily account for all the bad effects of hard water on the human body ; and (how, that, by the feparation of the a- cid from the terreftrial bafe, which muft happen in the body, feveral difeafes muft arife ; fuch as, the ftone and gravel, rheu- matifm, colics, gout, and many others ; but this is not the proper place. Thefe unhealthful effects of hard water may be eafily prevented, by mixing alkaline falts with it. The hard water I have ufed in thefe experiments, takes about 1 dr. to one Mnglijh pint : A very fmall quantity to pro- duce fo excellent an effedt. The milky water muft be allowed to ftand till it be- comes clear, before it is ufed for drink. To difcover whether the effedt of hard- ening vegetables depended on the acid, or on the earthy particles left in the fubftance, I tried the following experiment. Exp. 133. Four different parcels of green peafe were boiled, for the fame time, in the fame degree of heat, in four different waters 5 viz. foft water j hard water 5 arti- ficial 296 EXPERIMENTS PartlV. ficial hard water, made with the abforbent bafe of the hard water, and the oil of vi- triol ; and fome foft water, with as many- drops of the fpirit of nitre in it as I thought was equal to the acid of the hard water* When the peafe of the foft water were e- nough boiled for eating, I took out the whole. The peafe in the hard water were fo hard, that they could not be eaten ; and at the fame time not fo green as thofe in the foft water. Thofe in the artificial hard water were like the former. Thofe in the water with the nitrous acid did not tafte a- cid, were lighter-coloured, and fofter than the reft; their fkins were moftly broke. The earth was found before not to harden water, and the acid is now. Hence it mull arife from the faline particles entering com- pounded, and the acid leaving the earthy behind ; which, from the volability of the former, muft foon happen. Hard water, though it does not make vegetables greener, as is generally thought; yet as it keeps them longer hard, it keeps them longer green. This SecSt. II. ON BLEACHING. 297 This method which we have difcover- ed * of foftening hard waters, is eafy, ex- peditious, and cheap qualities abfolutely neceflary to render it ufeful to the public. It is eafy, as the moft ignorant can do it ; expeditious, as it becomes fit for all family- ufes immediately, and for drinking in half an hour ; and cheap, as the material cofts but a mere trifle ; nay may be prepared by any perfon. By this change, the hard wa- ter not only becomes fit for all the common ufes of life, but as beneficial as it was be- fore hurtful to the health of man. Lord Verulam had fo high an opinion of the falu- tary effedts of nitre, that, as we are told, he ufed to mix it with all the water he drank. Hard water, when corrected by al- * I have difcovered, fince thefe papers were in the prefs, that Dr Shaw, in his chymical difcourfes, has given an im- perfect hint of this quality of alkaline falts. He fays, that hard water becomes fofter by an addition of alkaline falts. I call this hint imperfect, becaufe hard waters may be made fofter, and yet continue hard, as they admit of various de- grees of hardnefs. The foregoing experiments (how, that all kinds of hard waters are altogether foftened by alkaline falts. Nor does the Doctor inform us of the manner of do- ing it, or reafons on which it depends, or qualities of the water after it is foftened. P p kaline 298 EXPERIMENTS Part IV. kaline falts, turns into foft water impregna- ted with nitre. I may venture to affirm, that no other material can ever be found capable of foftening hard water : and tho' one was difcovered endued with the fame property, it could not be of the fame ufe to mankind, as there is none, alkaline falts ex- cepted, to be had every where. A particu- lar fubftance or plant was only to be found in particular places, but this material is to be got where-ever plants grow. So kind is the general parent of nature, that he has provided a remedy, every where to be found, for fo common an evil ; but, at the fame time, has left the difcovery to our own in- duftry. How much we flood in need of fuch a difcovery, moft great towns, efpecially thofe on the fea-coaft, nay the greateft part of fome counties, can teftify. Newcajile is a remarkable inftance of this diftrefs. In all the pants or pipes there, two excepted, the water is hard ; and to fuch a degree, that it is three times more fo than the hard wa- ter which I have examined. The nitrous acid, Se6l.IL ON BLEACHING. 299 acid, joined to an abforbent bafe, is the caufe. The precipitation from thefe waters, by the means of alkaline falts, was in fo great plenty, that the fourth part of the glafs was covered with it, and amazed not a little thofe who made ufe of the water. There the old and infirm complain, that thefe hard waters give them a fournefs of the ftomach, and colics, As the ftrength of different alkaline falts differ, and as fome hard waters are much harder than others, nay the fame water harder in dry than in wet weather, fome eafy and certain general rule of foftening all hard waters is neceffary ; the following appears to me the beft. Let a certain quan- tity of alkaline fait be diffolved in a certain quantity of foft v/ater. Into a certain quan- tity of hard water in a glafs pour in the fo- lution gradually, fo long as the milky co- lour is on the ificreafe. When that is at the height, let the water fcand till it be- comes pellucid. Try it again with a few drops of the folution ; if no whitenefs arifes in the water, it is then foft 5 if there does, P p 2 go 3 oo EXPERIMENTS PartlV. go on drop by drop until no more white clouds arife. Bv this means it is known what quantity of falts is neceflary to foften that quantity of water ; and, confequently, how much any given quantity of water will require. Quar i . Is not hard water more nourifh- ing for vegetables than foft water ? I ima- gine, that the fait of vegetables enters their veffels in fuch a form as this fait of hard waters. The fait like wife feems to be of the nitrous kind ; which we think the nou- rishment of plants. As this query is oppo- fite to the general opinion, (for no gardener will make ufe of hard water, if he can fhun it), I watered fome plants with it, and thought that they grew better than thofe which were watered with foft water. Queer. 2. May not hard water be pro- per for fome particular conftitutions, and for fome particular difeafes, fuch as putrid fevers, &c. ? The antifeptic quality of thefe waters would feem to be ufeful to putrefcent habits. Queer* Sea. II. ON BLEACHING. 301 Queer. 3. Do thefe hard waters fupply the air with a nitrous acid ? We have difcover- ed by thefe experiments, that the nitrous acid of this water is eafily feparated, by a boiling heat, from its abforbent bafe ; and that it arifes even by a gentle diftilla- tion. We find like wife, that all hard wa- ters depofit more or lefs of an abforbent earth. Hence we may reafonably conclude, that there is a real nitrous acid, diftindt from the vitriolic acid, communicated by thefe hard waters, to the air ; and that from the former, and not from the latter, as chymifts have imagined, nitre is generated. This is further confirmed by an obfervation of the learned Dr Pluminer, who fays, that he has oftener obferved nitre produced or regene- rated, than vitriolated tartar, from an alka- line lixive long expofed to the air. Queer. 4. Is not hard water more proper to be carried to fea than foft water, as it ap- pears to refift putrefaction very powerfully ? Queer. 5, Is not the caufe of hard and petrifying 3 02 EXPERIMENTS Part IV. petrifying waters the fame ? and do not they differ only in degree ? When the faline fub- ftance impregnates the water very ftrongly, the earth, depofited in the interftices of any fubftance, muft be continually on the in- creafe, till at laft the fubftance becomes a ftone. This I imagine is the way that all petrifying waters a£t, and accounts very na- turally for their effects, Queer. 6. Do not the brewers, in great cities, who generally make ufe of hard wa- ter, lofe a very great part of the fubftance of their malt, as we have found hard water very unfit for drawing a tinfture from any vegetable ? Will not hard water, foftened in this way, make ale of a much greater ftrength from the fame quantity of malt ? and what effect will nitre have on ale ? Queer, y. Do hard waters contribute to flerility, as Hippocrates afferts ? Queer. 8. Muft not hard waters have in general a very bad effed on digeftion, as they tend Sea.IL ON BLEACHING. 303 tend to keep all bodies in their natural found ftate ? Queer. 9. How happens it that Brijlol wa- ter is reckoned fo exceedingly foft, in- fomuch that it is thought to come from chalk, when it is really a hard water ? What acid does it contain ? Are not its ef- fects in confumptive he£tic cafes owing to this imperfed: neutral fait ? Queer. 10. Is not the effe£t of hard water in turning pewter black, owing to a fo- lution of the metal by the acid ? Queer. 1 1 . Are all waters hard which lie at a confiderable depth below the furface of the earth ? and is it not necefTary that thefe fhould have fome particles in their compofi- tion of an antifeptic nature, to refift the ef- fects of heat and ftagnation, to which they are liable ? S E C T. 304 EXPERIMENTS Part IV. SECT. III. The effects of fteel and coal waters on cloth, and the cure. H Ardness is not the only pernicious quality in waters which the bleacher has to fhun. All impregnations with bodies fuipended in that fluid, whether they are earthy, faline, or metallic, retard, nay oft- en entirely ftopt the whitening of cloth. There are two fpecies of waters particularly deftrudive in this art, I mean vitriolic or chalybeate waters, and coal waters. As thefe are very common in this country, the bleacher ought to be more upon his guard againft them. It therefore becomes necef- fary for him to be able to diftinguifh them from other waters, and to remove their bad efFedts when they happen to be ufed. All fteel waters, whether the iron be diffolved by an acid or not, depofitate a red fubftance, called ochre. This is to be ob- ferved in the channel where thefe waters run. Se6t.HL ON BLEACHING. 305 run. It is moftly compofed of the particles of iron precipitated to the bottom, with a fmall addition of whatever faline fubftance exifls in the water. Thefe particles are de- pofited, continually, on the furface of the cloth, when watered with a chalybeate wa- ter, and effectually flop all further progrefs in whitenefs. This happened to a poor wo- man, who watered fome webs fhe was bleaching from a fpring near her own houfe. To her great furprife they turned redder and redder every day. Not being able to account for this effect in a natural way, or to remove that colour, fhe imputed it to witchcraft, blamed the neighbour fhe hated mofl, and fold them for a trifle. That wa- ter was afterwards difcovered to be a mine- ral fpring. Had fhe confulted a chymift, he would have fhown her a method of diffolving the charm. Water, with the addition of a fmall proportion of oil of vitriol, would have carried off the ochrey matter. I watdred fome white linen with the Harffield fpaw water, till it had acquired a pretty ftrong red Q_q colour. 3 o6 EXPERIMENTS Part IV. colour. This linen fteeped in water gently acidulated with vitriol, in a few hours, came out white again. I am not lure, however, whether all ochres can be diffolved by acids. I have tried fome which were not. Againfl thefe I know no remedy. It is therefore of great confequence to the bleacher, that he fhould be able to dif- tinguifh thefe waters, when he meets them, from others, in order to fhun them in the iituation of his bleachfield. The charadte- riftical mark of thefe waters, is, That they turn purple or black with galls, green tea, or the leaves or bark of the oak. If this effe£t happens, on the mixture of thefe bo- dies, the water is improper for bleaching. There is an ochrey fubftance, like the former in appearance, which has not yet, fo far as I know, undergone any examination y I mean that of coal waters. Whenever they are ufed in the watering of cloth, they leave a yellow colour. That we may be able to remove thefe particles when lying on the furface of cloth, it becomes neceffary to ex- amine SedtXlL ON BLEACHING. 307 amine their nature, and to difcover their proper folvent. This examination will be attended with another advantage. This ochrey fubftance is reckoned one of the fureft marks of coal. But how can it be depended on, when many waters, which do not come from coal, have a like appearance, and when the dif- tinguifhing properties of thefe fimilar fub- fiances are not afcertained ? A chymical ex- amination is the only method to fix thefe. I have elfewhere examined the ochre of mi- neral waters, and difcovered its properties and nature *. I fhall endeavour, here, to do the fame with that of coal waters. The ochre I made ufe of was taken up carefully from the channel of a coal-level, and had been kept by me near a year. Exp. 134. The ochre of coal waters has no particular tafte, and feels in the mouth gritty, and not fat> as that of mineral wa- ters does. * EfTay on Dun/e fpaw. 0_ q 2 When 3 o8 EXPERIMENTS PartIV, When put on a red-hot iron, it fparkles^ but emits no fulphureous or acid fleams. Half a drachm of it mixed with warm Water, and the liquor ftrained and evapora- ted, gave a fmall quantity of a faline refi- duum y which liquified in the air, tafted fharp, and rendered half an ounce of water reddifh and hard. Paper dipped in this li- quor, burnt like a match, and difcovered the fait to be nitrous. It effervefced with water acidulated with oil of vitriol. The liquor, with an addition of galls, turned into an ink. When thrown on melted nitre, it fparkled, but did not de- flagrate. The magnet has no effect on it before calcination. Twenty grains, calcined for two hours in a fire, were reduced to 14, and were all attracted by the magnet. Two drachms and a half were diftilled, and gave me about 1-^ dr. of a liquor, which turned fyrup of violets green, effervefced with Se6l.IV. ON BLEACHING. 309 with mineral and vegetable acids, and had the fmell of fpirit of hartfhorn. From this experiment; then, we difco- ver the nature and properties of coal ochre. We fee that it is compounded of iron, and a neutral fait, like that of all hard waters. We obferve, likewife, its proper folvent, oil of vitriol diluted with water ; and that the fame mixture which removes the ochre of mineral waters, will remove this. But what is perhaps of greater moment, its properties appear to be very different from thofe of other ochres. If fuch a fubftance was pre- fented to me, I think I could tell whether it came from coal or not. SEC T. IV. Some confederations with regard to the further improvement of our linen manufatfure* t J S HE demand for manufactures is in I proportion to their goodnefs and cheapnefs. That country which affords the 3 io EXPERIMENTS Partis the bed, and at the loweft prices, will find the readieft market. To thefe two points muft every defigned improvement tend. For that end the foregoing experiments were calculated. I have endeavoured, by their affiftance, to fhow where the com- mon practice was right, and where wrong ; to propofe fome improvements in it 5 to in- troduce new materials made at home 5 and to fhorten the time of fome operations con- fiderably ; to explain the principles upon which the whole is conducted ; and, in ffiort, to make the bleachers underftand their art thoroughly ; the only method to make them operate better and cheaper, without diminifhing their gains. I am very fenfible how difficult a thing it is to alter the eftablifhed opinions of man- kind ; and how much more difficult to al- ter their pradice. As the experiments in this difquifition have been many, and the reafonings few, the author can never exped: to pafs for a theorift : but confidering the prejudices of mankind, the trouble of ma- king proper trials, and the qualities requi- fite Sea. IV. ON BLEACHING. 311 fite for fuch a work, their efFeCts in the bleachfield muft be but very flow. It is reafonable they fhould be fo. Alterations in the common practice of the arts are too dangerous, both for the public and particu- lars, to be haflily gone into. But yet when Experience points the way, it is unpardon- able to negled: its advice. Having now fecured the moll import- ant and dangerous part of our linen manu- facture, let us caft our eyes on the other branches, and conflder if there be not room likewife for further improvement in thefe. Every manufacturing country ought, if pof- fible, to have the materials of their manu- facture produced within the country 5 that it may not depend upon foreigners, nay per- haps upon their rivals in trade, whether they fhall have a manufacture or not. The Ho- nourable board of truftees for fifheries and manufactures have given all attention to this point ; and, by proper regulations and pre- miums, have endeavoured to encourage the growth of flax at home : but all they have done has been yet attended with little fuc- cefs j 3 i2 EXPERIMENTS PartlV. cefs ; and I am afraid, if fome fpeedy affift- ance is not given, things will rather turn worfe than better. Complaints have been made by manufacturers-, that our home flax is not fo good as the foreign. I am of opi- nion, that it is more owing to our want of fkill in watering of it, than to our foil, or methods of managing it there. We have all kinds of grounds, and excellent rules laid down for their culture : but the pro- cefs of watering feems not yet thorough- ly underftood ; and the practice, as carried on by the commonalty all over the country, is rnoft deftru&ive to the flax. As it is of fuch importance to our manufacture, and as it is a chymical operation, we think it de- fer ves our confederation, in a treatife de- figned to improve our manufacture by the affiftance of chymiftry. Whoever will attend to what pafles du- ring the fteeping of lint in ftanding water, and during fair weather, or will make the experiment in the houfe, muft find it at- tended with the following circumftances. On the fecond or third day, if the weather is Seft. IV. ON BLEACHING. 313 is warm, a great many air-bubbles arife to the furface of the water, and by degrees a fcum or pellicle gathers there, which is full of thefe air-bubbles. The water gains a fmall degree of heat, and a corrupted fmell. If the flax is allowed to lie too long, it turns corrupted, black, and lofes all tena- city. Thefe effedts evidently fhow, that the procefs of fteeping flax is the procefs of pu- trefaction carried on to a certain length. Every one knows, that the intention of fteeping is to loofen the harl or bark of the flax from the bun or woody part of that plant; and that it is to be accomplished by a folution of the oil, or mucilaginous fub- ftance, which makes them cohere. Putre- faction is the inftrument at prefent employ- ed to attain that end. The inteftine motion raifed by it, difunites, attenuates, and dif- folves that vegetable glue, and renders it mifcible with water. The great art is to know when that is done. If the flax is al- lowed to lie any longer in the water, that oil which unites the folid particles of the R r harl 3 14 EXPERIMENTS PartlV. harl is diffolved, and the fibres lofe all ftrength. The time which flax muft lie in the wa- ter, is to be meafured, then, entirely by the quicknefs or flownefs of the putrefa&ion. As this depends on the concurrence of ma- ny circumftances, viz. the nature of the flax, its quantity, the heat of the. weather, length of the nights, nature and quantity of the water, and many others, it is impoflible to fix a certain time. The flax, when fuf- ficiently watered, acquires a flippery oilinefs on its fkin, owing to a folution of that mu- cilage mentioned before : but Pliny's rule is ftill the moll certain, Maceralos indicio eji membrana laxatior^ lib. 19. The flax ought therefore to be infpe&ed, after the fourth day, every fix hours ; and when the bun appears brittle, and the harl feparates from it, the flax ought to be immediately taken out. Nor ought we to wait, as is judiciouf- ly obferved in the Dublin e flays, till the re- paration becomes too eafy ; but leave that to be completed by the dews and warmth when expofed on the grafs. , As the danger v 1 il is Se6fc. IV. ON BLEACHING. 315 is great in allowing it to lie too long, fo there are feveral bad efFedts arifing from taking it out too foon. The black bars which run acrofs the linen, and are fo dif- ficult to remove in bleaching, are none of the leaft. To whiten thefe, the reft of the cloth is often damaged. When flax has been kept fomewhat too long in the water, none of. thefe black bars are to be feen. They increafe in proportion to the deficien- cy or failure in that degree of putrefaction neceflary to fteeping. I am told by an ex- perienced bleacher, that he prevents, in a great meafure, thefe black bars, by fouring the yarn after it has been boiled with aflies. When we once understand how this procefs is carried on by nature, we will foon fee what is the bufinefs of art. We muft regulate the procefs of putrefaction fo that it does not meet with too great obftacles to flop it, nor be allowed to go on too rapid- ly. The latter muft feldom be the cale in this climate ; but the former often. Run- ning water muft appear at firft fight entirely improper for fteeping lint, as the corrupted R r 2 particles 3 i6 EXPERIMENTS PartlV. particles are continually carried off. Springs have the fame fault in a leffer degree. No- thing promotes putrefaction fo much as quietnefs and heat ; nothing flops it more than agitation and cold. Steeping ought always then to be performed in a place as much fheltered from the winds, and in a feafon when it will have as much heat as poffible. I would chufe that the water fhould not be too fhallow, that it may not be too fuddenly affe£ted by the coldnefs of the night, or other changes of weather. The more uniform the heat of the water is, the more fafe the procefs will be. Ponds made at the fides of lakes or of rivers, not too near their fource, appear in general to be the moll eligible places. If the procefs goes on too flow, on account of the nature of the lint, water, or weather, chymiftry teaches us how to quicken it. The putrid fermentation can be checked or quickened, as well as the vinous. As yeaft increafes the latter, fo do all putrid bodies the for- mer. Some putrid vegetable fubfiapce mix- ed with the water, would anfwer this pur- pofe. From Se6l.IV. ON BLEACHING. 317 FroM what has been faid, we may eafily account for the practice of the Dutch, who lay the dirt and mire found at the bottom of their fteeping ponds, on the furface of the flax after it is laid in the water. When that corruptible matter lies there, it communi- cates putrefaction to the water more equally than if it lay at the bottom. We likewife fee the reafon why thofe who underftand the fteeping of flax, never allow it to touch the ground : for when that happens, the flax which lies there, bearing the preflure of all above it, putrifies fooner and fafter than' what lies above. We may likewife account for another fad", that flax mull lie four or five months in mofs- water before it is fufficiently watered. Mofs-water, fo far from corrupting, preferves even animal bo- dies from corruption. This water is too much ufed in this country, and highly pre- judicial to the flax. But, of all waters, none feem fo bad as thofe which have a confiderable degree of hardnefs, becaufe thefe have already fhown themfelves to be almoft incorruptible. Common 318 EXPERIMENTS PartlV. Common pra&ice had difcovered this with- out knowing the reafon of it, and therefore hard waters are marked as improper. If they muft be ufed, we are ordered to fill the ponds, and expofe the water to the fun for fome weeks *. But it has appeared from undoubted experiments, that there are ma- ny degrees of hardnefs, which have not hi- therto been difcoverable ; and that expofi- tion to the fun is not a remedy againft hard waters. We have difcovered a criterion for the former, by which we are able to per- ceive the fmalleft degrees of hardnefs 5 and a cure for the latter, in cafe we are neceffi- tated to ufe it. Let us then, by experi- ment, try the effedts of hard water on flax ; and fee if thefe effe&s can be removed, by being foftened in the way I have defcribed. Exp. j 35. Sept. 1 1. I fteeped equal quan- tities of flax in three different kinds of wa- ters, viz.- hard water, the fame foftened with alkaline falts, and foft water. The laft, though it broke foap, and was the foft- * Vid. Dublin Effays. eft Sed.IV. ON BLEACHING. . 319 eft in the place where I tried this experi- ment, was not fo foft as I could have wish- ed. On the 14th they all had a fcum, with air-bubbles on their furface ; but the hard water had the leaft. On the 17th all the waters had a putrid fmell ; the hard and foft waters were pale-coloured, but the hard water foftened was of a high colour. On adding fome alkaline falts to a cupful of the foft water, it turned almoft as high in the colour as the former. The flax in the foftened water, was the only one of the three whofe fkin felt oily. Some of each parcel being dried, that taken out of the foftened water was of a higher colour than the other two, and was rather too much watered 5 that from the foft water not fuffi- ciently ; that from the hard water no better than when put in. On the 20th, the flax in the foft water appeared to be completely watered. On the 24th, the flax in the hard water was almoft watered, but its Ikin did not feel flippery as the others had done. This experiment fhows the bad efFe&s of hard water in fteeping flax, and at the fame time how to cure thefe, The 3 2 b EX P E RIMENTS Part IV. The procefs of putrefa&ion, by which the prefent method of fteeping flax is car- ried on, admits of too great variety with regard to weather and water, and is too dan- gerous to be managed with fafety by the commonalty. It would be much for our advantage, and I have often thought it pof- fible, to difcover a fafer method than that at prefent ufed. I was inclined to think, that the addition of alkaline falts to the wa- ter might anfwer that purpofe. For the qualities requifite in fuch a body, were to I'efift putrefaction, and diflTolve the oil be- twixt the harl and the bun ; and thefe two qualities appeared to me to be inherent in thefe falts. As I never make any ufe of theory, but to lead me to experiment, I made the following. Exp. 136. Sept. 26. Some flax was fteep- ed in foft water ; an equal parcel in the fame quantity of water, with the addition of 2 dr. of pearl falts to each EngliJJo pint and a half ; another parcel in the fame quantity of water, with 1 oz. inftead of 2 dr. OB. 2. The firft parcel was fufficiently fteeped ; the fecond Seft. IV. ON BLEACHING. 321 fecond not fit for taking out ; and the third ftill further removed from that ftate. OB. 7. The fecond was finifhed ; but when dried, feemed very brittle. The third was no bet- ter than when put in. The next thing to the relation of fuo cefsful experiments, is the relation of un- fuccefsful ones. Even thefe are attended with many advantages. However unfuccefs- ful the laft has been, I do not yet defpair of finding out fome body which will anfwer all the ends of putrefadtion without the danger of it. In the mean time, it appears highly neceflary, that fteeping fhould be made a bufinefs diftindt from the raifing of flax. In Holland it is managed by lint- dreffers, who buy the flax ftanding on the ground. I am apt to think, that the great flop to the progrefs of our linen manufacture lies in this very point, the fteeping of flax. Our farmers, by the Wife regulations of the board of Truftees, feem to underftand the culture of flax well enough ; and, notwithftanding S f fome 3 22 EXPERIMENTS Part IV. fome fmall difadvantages from the nature of our climate, would raife it in fufficient quantity, and find their profit in it, if they could difpofe of it, before fteeping, to a fet of people who underftood that procefs. The farmer is at prefent unwilling to deal in it, becaufe, though he raifes flax of the beft kind, it is generally fpoiled in the wa- tering, and becomes of lefs value than the foreign. The fteeping and drefling of flax ought, therefore, to be made a diftindt bu- finefs ; and, as it is the branch of our linen manufacture leaft underftood, fhould be moft encouraged. All premiums in arts and manufactures, ought to be directed to thofe branches which are leaft underftood. It would feem at firft neceftary to bring over a fet of Dutch lint-dreflers, by proper encou- ragement, and that premiums fhould be gi- ven to thofe lint-dreflers who produced the greateft quantities of the beft drefled Scots lint From what I have faid on bleaching, it appears, that cloth, from its hard and firm texture, refifts for a long time the entrance of Sea. IV. ON BLEACHING. 323 of thofe materials which are to whiten it. But the lint and yarn are not fubjedt to this objection. Would it not, then, fave a great deal of trouble, expence, and hazard, if thefe were bleached, at leaft in part, before they went into the loom ? I am afraid it would not be fo eafy to manage the lint, as it is fo light a body ; but as for the yarn, I can difcover no material objection againft it. One I have heard, and that is, The yarn would become too oozy. But that fault, I imagine, could be corrected by the weaving, and the gentle bleaching which would after- wards be necelTary. It is the opinion of all the bleachers, that the cloth of this country is of too thick a fabric, owing to the coarfenefs of the woof. I agree with them. That fpecies of cloth requires fo many buckings before the falts can penetrate into the inner parts, that the external threads are too often deftroyed be- fore the internal are whitened. On the contrary, the thinnefs of the oppofite fpecies of cloths is more than counterbalanced by the prefervation of its fabric in the bleach- S f 2 field. ■ 3 24 EXPERIMENTS PartlV. field. Befides, the expence of bleaching thin cloth is not near fo great as that of bleach- ing thick. The former retain their colour better, and appear finer at the fame price ; which will always recommend them to the merchant. There is nothing promotes an art fafter than the communication of thofe who prac- tife it ; nothing retards it more than a felf- i(h fpirit of keeping all a fecret. It is by a gradual progrefs, where one refines upon the inventions of another, and not by the endeavours of a fingle perfon, that arts ar- rive at perfection. I cannot, then, but re- commend to the Honourable Board of Tru- ftees, a fcheme of Mr John Chryjiie. He not only has made many advances himfelf in this art, but is defirous that others fhould do the fame. He propofes, that every bleacher, efpecially thofe who have got, or expeCt any premium from the Truftees, fhould annually deliver an exaCt account of his method of bleaching. If this propofal took place, feveral faults would be obferved and correded ; feveral advantages gained ; the Sedt.IV. ON BLEACHING. 325 the bleachers made more knowing, as one may excel in a particular branch, who is very- deficient in all the reft ; a complete hiftory of the praCtice made out ; and the art itfelf arrive at perfection. Let thofe who fhelter themfelves under the appearance of fecrets, know, that ignorance always does the fame. I know nothing that muft have been of greater advantage to the linen manufacture of Ireland^ than their linen hall. The ma- nufacturer brings his cloth there, is provi- ded by the public with a proper apartment for his goods, and is fure of a market in a few days. The public, having the cloth under its eye, is affured of its goodnefs, and proves a continual check to private frauds. The foreign merchant, knowing where he can fupply himfelf at once, is under no ne- ceffity of adting by commiffion at a diftance, or if he fhould come, of dealing with re- tailers ; but reforts to this market, and makes his bargain with the manufacturer himfelf. Thefe confiderations make their cloth go better and cheaper to foreign mar- kets, and are alone fufficient to overpower any \ 326 EXPERIMENTS PartlV. any nation who does not follow fuch a pru- dent condu6L To you, Gentlemen, who are pofTeffed of landed eftates, I muft now apply myfelf. You are, or may be, the great promoters and direc- tors of induftry among your tenants and de- pendents. It is from you that the common- alty will take that bias of mind, which makes them ufeful or ufelefs fervants of the public. It is in your power, by procuring materials at the cheapeft rates ; by encouraging the induftrious, and difcouraging the flothful ; by fmall premiums to excite emulation j by taking the rents of your houfes in manufac- tured goods, rather than money ; by inftitu- ting markets at proper times for the fale of yarn ; and by many other methods, to raife a fpirit of labour and induftry. There is nothing feems more to be de- fired, than a change in the education of the young people of both fexes. While it conti- nues on the prefent plan, of educating them, at a public fchool, to reading, writing, and compting, I have no hopes of feeing them very Se6l.IV. ON BLEACHING. 327 very indubious. That habit can only be got when young. By the prefent plan they are a burden on their parents till they are fully grown up, while they might be ac- quiring ftrong habits of induftry, earning their own bread, and adding to the wealth of their country. The confequences of this education are vifible, after the men have ap- plied to day-labour ; for they know not how to turn to any account four or five hours e- very night during the winter, too much time to be loft, and which might yield a confiderable advantage, if they had been taught fpinning, or any other fpecies of ma- nufacture. It is well if this turn to fpecu- lative knowledge, which they have got, is attended with no worfe confequences. It would be for the advantage of this country, nay for the real happinefs of its inhabitants, that we had fpinning-miftrelfes, as well as fchoolmafters, in every parifh. Necessity is allowed to be the greateft ■fpur to induftry. People work not for "plea- fure, but for a livelihood. When that is eafily procured, as in cheap years, induftry abates 5 328 EXPERIMENTS PartlV. abates ; when with greater difficulty, as in dear years, induftry increafes. I have often thought, that thofe forry cloaths, houfes, and meals, to which our commonalty has been accuftomed, inftead of being affiftants, as they may appear at firft fight, were great enemies to our growing manufactures. Our people work but in proportion to their de- mands j and if at any time they have more money than fupplies them, it is fpent in drink. It is only the gentlemen who can bring about a change in thefe articles. Till I can fee a greater degree of refinement ; till I can hear that our commonalty are pof- fefled of ftronger defires with regard to thofe conveniencies of life than they are at prefent, I fhall expedt no change in their a&ivity. It is to the government we muft chiefly be indebted for the progrefs of our linen manufacture. It is there alone that eafe can be had from the duties on foap and afhes> which bear hard on our manufacture. It is there alone that a conftant market can be provided for us, by encouraging the ex- portation Scft.IV. ON BLEACHING. 329 portation of our otvn, and difcouraging that of foreign cloth; and by other methods which the wifdom of the nation fhall think proper. Without fome proper and fpeedy encouragement of this kind, our manufac- ture muft foon decline ; perhaps it does fo at prefent. No induftry on our fide can pof- libly counterbalance thofe heavy taxes which we pay on all the necelfaries of life, and which our rivals in trade know nothing of. If we are obliged to give up the linen, we muft endeavour to cultivate the woollen ma- nufacture, whofe feeds are already fown in this country. I look on it as a lofs to Great Britain, and to arts and manufactures, that we have no academy inftituted by public authority, and at the public charge, to which the care and further progrefs of thefe might be in- trufted ; and whofe members, fecured in a decent livelihood, might follow the natural bent of their genius ; and hear, with fafety, the enthufiaftic voice of Fame. What a trifling fum to France is the yearly expence of the Academy of Sciences ! and yet of T t what 330 EXPERIMENTS. PartIV, what benefit has it been to the arts and ma- nufactures of that country ! Their fuperio- rity in many arts, and efpecially in dying, has been entirely owing to the labours of this fociety. Lewis XIV. in whofe reign this academy was inftituted, has gained vic- tories by it over thofe whom his fword could not fubdue. FINIS, THE GETTY CENTER