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ELEMENTS 
 
 OF 
 
 IN 
 A COURSE OF LECTURES 
 
 BY 
 
 F. R. S. L. ^- E. V. P. R. 1. 
 
 MEMBER OF THE BOARS OF AGRICULTURE, OF THE ROYAE IRISH ACADEMY, OF THE 
 ACADEMIES OF ST. PETERSBURKH, STOCKHOLM, BERLIN, PHILADELPHIA, &€., AJIII 
 HONORART PROFESSOR OF CHEMISTRY TO THE ROYAL INSTITUTIOX. 
 
 TO WHICH IS ADDED, 
 
 A TREATISE ON SOILS AND MANURES, 
 
 AS 
 
 t 
 
 FOUNDED ON ACTUAL EXPERIENCE, 
 
 AND 
 
 AS COMBINED WITH THE LEADING PRINCIPLES 
 
 IN WHICH THE 
 
 ijHEORY AND DOCTRINES OF SIR HUMPHRY DAVY, 
 
 AND OTHER AGRICULTURAL CHEMISTS, 
 
 kUB RENDERED FAMILIAR TO THE EXPERIENCED FARMER. 
 
 BY A PRACTICAL AGRICULTURIST. 
 
 PHILADELPHIA: 
 
 PUBLISHED BY B. WARNER, M. CAUEY &C SON, AND BENNETT & WALTON: 
 
 AND IN BALTIMORE, 
 
 BY F. LUCAS .TR., JOSEPH CUSHING, AND EDWARD .1. COALE. 
 
 1821 
 

 tiiiggs & Dickkuon— PviWei-s. 
 
 

 ir^E^ll^EKT aXD 2VIE3^15E11S 
 
 THE BOARD OF AGRICULTURE 
 
 FOR THE YEAR 1812, 
 
 •JPllia^® SLI3(0^IiIBS©3 
 
 PUBLISHED AT THEIR REQUEST, 
 
 ARE IXSCRIBEI) AS A 
 
 TESTIMONY OF THE RESPECT OF THE AUTHOR, 
 
 HIS GRATITUDE FOR THE ATTENTION WITH WHICH 
 THEY HAVE BEEN RECEIVED. 
 
V- 
 
 AIDTSIB^Il^SllSa^i 
 
 During ten years, since 1802, I have had the honour? 
 every Session, of delivering Courses of Lectures before the 
 Board of Agriculture. I have endeavoured, at all times, to 
 follow in them the progress of chemical discovery ; they have 
 therefore varied every year : and such is the rapidity with 
 which Chemistry is extending, that some alterations and im- 
 provements were rendered necessary at the time they were 
 preparing for the press. 
 
 The Duke of Bedford has enabled me to stamp a value 
 upon this Work, by permitting me to add to it the results of 
 the experiments instituted by His Grace upon the quantity 
 of produce afforded by the different grasses. 
 
 I am indebted for much useful information to many mem- 
 bers of the Board ; of which acknowledgements will be 
 found in the body of the Work. If there are any omis- 
 sions on this head, I trust they will be attributed to defect of 
 recollection, and not to any want of candour or of gra- 
 titude. 
 
 Where I have derived any specific statements from books, 
 I have always quoted the authors ; but I have not always 
 made references to such doctrines as are become current, the 
 authors of which are well known ; and which may be almost 
 considered as the property of all enlightened minds. 
 
 Amongst books to whicii I have not referred for any par- 
 ticular facts, but which contain much useful general informa- 
 tion, I shall mention the Earl of Dundonald's Treatise on 
 
VI ADVERTISEMENT. 
 
 the Connprtion of Chemistry wicii Agriculture ; Dr. Rennie's 
 Dissertations on Peat ; and the General Report of the Agri- 
 culture of Scotland. This last work did not come into my 
 hands till the concluding sheets of these Lectures were print-' 
 ing Had it been in circulation before, I should have profit- 
 ed by many statements given in it, particularly those of the 
 opinions of the enlightened Professor of Agriculture in the 
 University of Edinburgh : and I should have dwelt with 
 sarisfaction on the importance given to some chemical doc- 
 trines by his experience. 
 
 Berkeley Square, March 21, 1813. 
 
©DS^ISS^^g; 
 
 LECTURE I. 
 
 Page 
 INTRODUCTION. Generar Views of the Objects of the 
 Course, and of the Order in which they are to be discussed, 9 
 
 LECTURE II. 
 
 Of the general Powers of Matter which influence Vegetation ; 
 of Gravitation, of Cohesion, of Chemical Attraction, of Heat, 
 of Light, of Electricity, ponderable Substances, Elements of 
 Matter, particularly those found in Vegetables, Laws of their 
 Combinations and Arrangements, ----- 27 
 
 LECTURE III. 
 
 On the Organization of Plants. Of the Roots, Trunk, and 
 Branches ; of their Structure. Of the Epidermis. Of the 
 cortical and alburnous Parts of Leaves, Flowers and Seeds. 
 Of the chemical Constitution of the Organs of Plants, and the 
 Substances found in them. Of mucilaginous, saccharine, 
 extractive, resinous, and oily Substances, and other vegetable 
 Compounds, their Arrangements in the Organs of Plants, 
 their Composition, Changes, and Uses, - - . - - 43 
 
 LECTURE IV. 
 
 On Soils ; their constituent Parts. On the Analysis of Soils. 
 Of the Uses of the Soil. Of the Rocks and Strata found 
 beneath Soils. Of the Improvement of Soils, - - 109 
 
 LECTURE V. 
 
 On the Nature and Constitution of the Atmosphere, and its In- 
 fluence on Vegetables. Of the Germination of Seeds. Of 
 the Functions of Plants in their different Stages of Growth ; 
 with a general View of the Progress of Vegetation, - 143 
 
Vlll CONTENTS. 
 
 LECTURE VI. 
 
 Page 
 Of Manures of vegetable and animal Origin. Of the Manner 
 in which they become the Nourishment of the Plant. Of 
 Fermentation and Putrefaction. Of the different Species of 
 Manures of Vegetable origin ; of the different Species of 
 animal Origin. Of mixed Manures, General Principles 
 with respect to the Use and Application of such Manures 184 
 
 LECTURE VIL 
 
 Of Manures of Mineral Origin, or fossile Manures ; their Pre- 
 paration, and the Manner in which thfcy act. Of Lirne in its 
 different States ; Operatioii of Lime as a Manure and a Ce- 
 ment ; different Combinations of Lime. Of Gypsum ; Ideas 
 respecting its Use. Of other Neutro-saline Compounds, 
 employed as Manures. Of Alkalies and alkaline Salts ; of 
 common Salt, - - - 211 
 
 LECTURE VIIL 
 
 On the Improvement of Lands by burning ; chemical Princi- 
 ples of this Operation. On Irrigation and its Effects. On 
 Fallowing ; its Disadvantages and Uses. On the convertible 
 Husbandry founded on regular Rotations of different Crops. 
 On Pasture. On various Agricultural Objects connected 
 with Chemistry. Conclusion, - - - - - 233 
 
 APPENDIX. 
 
 An Account of the Results of Experiments on the Produce and 
 Nutritive Qualities of different Grasses, and other Plants, 
 used as the Food of Aniuials. - - - - . - 253 
 
A ©©llliSlS ®W lLm®^WWM^9 ^c 
 
 LECTURE I. 
 
 Introduction. General Views of the Objects of the 
 Course, and of the Order in itliich they are to he dis- 
 cussed, 
 
 xT is with great pleasure that I receive the permission 
 to address so distinguished and enlightened an Au- 
 dience on the subject of Agricultural Chemistry. 
 
 That any thing which I am able to bring forward, 
 should be thought worthy the attention of the Board of 
 Agriculture, I consider as an honour; and I shall en-' 
 deavour to prove iny gratitude, by employing every ex- 
 ertion to illustrate this department of knowledge, and 
 to point out its uses. 
 
 In attempting these objects, the peculiar state of the 
 inquiry presents many difficulties to a Lecturer. Agri- 
 cultural Chemistry has not yet received a regular and 
 systematic form. It lias been pursued by competent 
 experimenters for a short time only ; the doctrines have 
 not as yet been collected into any elementary treatise ; 
 and on an occasion when I am obliged to trust so much 
 to my own arrangements, and to my own limited in- 
 formation, I cannot but feel diffident as to the interest 
 that may be excited, and doubtful of the success of the 
 undertaking. 1 know, however, that your candour will 
 induce you not to expect anything like a iinished work 
 upon a science as yet in its infancy ; and I am sure 
 you will receive with indulgence the tirst attempt made 
 to illustrate it, in a distinct course of public lectures. 
 
 Agricultural Chemistry has for its objects all those 
 changes in the arrangements of matter connected with 
 the growth and nourishment of plants ; the conipara- 
 
10 
 
 live values of their produce as food ; the constitution 
 of soils ; the manner in which lands are enriched by 
 m<inure, or rendered fertile by the difterent processes of 
 cultivation. Inquiries of such a nature cannot but be 
 interesting and important, both to the theoretical agri- 
 culturist, and to the practical farmer. To the first, 
 they are necessary in "supplying most of the fundamen- 
 tal principles on which the theory of the art depends. 
 To the second, they are useful in affording simple and 
 easy experiments for directing his labours, and for en- 
 abling him to pursue a certain and systematic plan of 
 improvement. 
 
 It is scarcely possible to enter upon any investiga- 
 tion in agriculture without finding it connected, more 
 or less, with doctrines or eludications derived from che- 
 mistry. 
 
 If land be unproductive, and a system of ameliora- 
 ting it is to be attempted, the sure method of obtaining 
 the object is by determining the cause of its sterility, 
 which must necessarily depend upon some defect in the 
 constitution of the soil, which may be easily discovered 
 by chemical analysis. 
 
 Some lands of good apparent texture are yet sterile 
 in a high degree ; and common observation and com- 
 mon practice afford no means of ascertaining the cause, 
 or of removing the effect. The application of chemi- 
 cal tests in such cases is obvious ; for the soil must 
 contain some noxious principle which may be easily 
 discovered, and probably easily destroyed. 
 
 Are any of the salts of iron present ? they may be 
 decomposed by lime. Is there an excess of siliceous 
 sand ? the system of improvement must depend on the 
 application of clay and calcareous matter. Is there a 
 defect of calcareous matter? the remedy is obvious. 
 Is an excess of vegetable matter indicated ? it may be 
 removed by liming, paring, and burning. Is there a 
 deficiency of vegetable matter ? it is to be supplied by 
 manure. 
 
 A question concerning the different kinds of lime- 
 stone to be employed in cultivation often occurs. To 
 determine this fully in the common way of experience, 
 would demand a considerable time, perhaps some years. 
 
11 
 
 and trials which might be injurious to crops ; but by 
 simple chemical tests the nature of a limestone is dis- 
 covered in a few minutes ; and the fitness of its appli- 
 cation, whether as a manure for different soils, or as a 
 cement, determined. 
 
 Peat earth of a certain consistence and composition 
 is an excellent manure; but there are some varieties of 
 peats which contain so large a quantity of ferruginous 
 matter as to be absolutely poisonous to plants. No- 
 thing can be more simple than the chemical operation 
 for determining the nature, and the probable uses of a 
 substance of this kind. 
 
 There has been no question on which more difference 
 of opinion has existed, than that of the state in whicli 
 manure ought to be ploughed into the land ; whether 
 recent, or when it has gone through the process of fer- 
 mentation? and this question is still a subject of dis- 
 cussion ; but whoever will refer to the simplest princi- 
 ples of chemistry, cannot entertain a doubt on the sub- 
 ject. As soon as dung begins to decompose, it tlirows 
 off its volatile parts, which are the most valuable and 
 most efficient. Dung which has fermented, so as to be- 
 come a mere soft cohesive mass, has generally lost from 
 one third to one half of its most useful constituent ele- 
 ments. It evidently should be applied as soon as fer- 
 mentation begins, that it may exert its full action upon 
 the plant, and lose none of its nutritive powers. 
 
 It would be easy to adduce a multitude of other in- 
 stances of the same kind ; but sufficient I trust has been 
 said to prove, that tlie connexion of Chemistry with 
 Agriculture is not founded on mere vague speculation, 
 but that it offers principles which ought to be under- 
 stood and followed, and which in their progression and 
 ultimate results, can hardly fail to be highly beneficial 
 to the community. 
 
 A view of the objects in this Course of Lectures, and 
 of the manner in which they are to be treated, will not, 
 I hope, be considered as an improper introduction. It 
 will inform you what you are to expect ; it will afford 
 a general idea of the connexion of the different parts of 
 the subject, and of their relative importance; it will 
 enable me to give some historical details of the progress 
 
12 
 
 of tliis branch of knowledge, and to re/ison from what 
 has been ascertained, concerning what remains to be in- 
 vestigated and discovered. 
 
 The phenomena of vegetation must be considered as 
 an important l)ranch of the science of organized nature; 
 but tliough exalted above inorganic matter, vegetables 
 are yet in a great measure dependent for their exist- 
 ence upon its laws. I'liey receive their nourishment 
 frcnn tiie external elements ; they assimilate it by means 
 of peculiar organs : and it is by examining their physi- 
 cal and chemical constitution, and the substances and 
 powers wliich act upon them, and the modilications 
 which they undergo, that the scientific principles of 
 Agricultural Chemistry are obtained. 
 
 According to these ideas, it is evident that the study 
 ought to be commenced by some general inquiries into 
 the composition and nature of material bodies, and the 
 laws of their changes. '^Fhe surface of the earth, the 
 atmosphere, and the water deposited from it, must either 
 together or separately .afford all the principles concerned 
 in vegetation ; and it is only by examining the chemical 
 nature of these principles, that we are capable of dis- 
 covering what is tlie food of plants, and the manner in 
 Avhich this food is supplied aiul prepared for their nou- 
 rishment. Tlie principles of the constitution of bodies, 
 consequently, will form the fiv^t subject for our consi- 
 deration. 
 
 By methods of analysis dependent upon chemical and 
 electrical instruments discovered in late times, it has 
 been ascertained that all the varieties of material sub- 
 stances may be resolved into a comparatively small 
 number of bodies, which, as they are not capable of 
 being decompounded, are considered in the present state 
 of chemical knowledge as elements. The bodies in- 
 capable of decomposition at present known are forty- 
 seven. Of these, thirty-eight are metals ; six are in- 
 flammable bodies ; and three substances which unite 
 with metal and inflammable bodies, and form witli 
 them acids, alkalies, earths, or other analogous com- 
 pounds. The chemical elements acted upon by attrac- 
 tive powers comltine in diflcrent aggregates. In their 
 simpler combinations, they produce various crystalline 
 
i-i 
 
 substances, distinguislied by the resjularity of their forms. 
 In more complicated arrangements they constitute tlie 
 varieties of vegetable and animal substances, bear the 
 higher character of organization, and are rendered sub- 
 servient to the purposes of life. And by the influence 
 of heat, light, and electrical powers, there is a constant 
 series of changes ; matter assumes new forms, the de- 
 struction of one order of beings tends to the conserva- 
 tion of another, solution and consolidation, decay and 
 renovation, are connected, and whilst the parts of the 
 system continue in a state of fluctuation and change, 
 the order and harmony of the whole remain unalterable. 
 
 After a general view has been taken of the nature of 
 the elements, and of the principles of chemical changes, 
 the next object will be tlie structure and constitution of 
 plants. In all plants there exists a system of tubes or 
 vessels, which in one extremity terminate in roots, and 
 at the other in leaves. It is by the capillary action of 
 the roots that fluid matter is taken up from the soil. 
 The sap in passing upwards becomes denser, and more 
 fitted to deposit solid matter : it is modified by exposure 
 to heat, light, and air in the leaves ; descends througli 
 the bark, in its progress produces new organized mat- 
 ter ; and is thus in its vernal and autumnal flow, the 
 cause of the formation of new parts, and of the more 
 perfect evolution of parts already formed. 
 
 In this part of the inquiry I shall endeavour to con- 
 nect together into a general view, the ol)scrvation of tbe 
 most enlightened philosophers who have studied the 
 physiology of vegetation. Those of Grew, Malpiglii, 
 Sennebier, Darwin, and, above all, of Mr. Kniglit. He 
 is the latest inquirer into these interesting subjects, and 
 his labours hav^ tended most to illustrate this part of the 
 economy of nature. 
 
 The chemical composition of plants has within the 
 last ten years, been elucidated by the experiments of a 
 number of chemical philosophers, both in this, and in 
 other countries ; and it forms a beautiful part of gene- 
 ral cliemistry ; it is too extensive to be treated of mi- 
 nutely ; but it will be necessary to dwell upon such 
 parts of it, as aftbrd practical inferences. 
 
 If the organs of plants be sul)mitted to chemical ana- 
 
14 
 
 lysis, it is found that their almost infinite diversity ot" 
 form, depends upon different arrangements and combi- 
 nations of a very few of the elements ; seldom more 
 than seven or eiglit belong to them, and three constitute 
 the greatest part of their organized matter ; and accord- 
 ing to the manner in which these elements are disposed, 
 arise the different properties of the products of vegeta- 
 tion, whether employed as food, or for other purposes 
 and wants of life. 
 
 The value and uses of every species of agricultural 
 produce, are most correctly estimated and applied, 
 when practical knowledge is assisted by principles 
 derived from chemistry. The compounds in vega- 
 tables really nutritive as the food of animals, are very 
 few ; farina or the pure matter of starch, gluten, sugar, 
 vegetable jelly, oil, and extract. Of these the most 
 nutritive is gluten, which approaches nearest in its na- 
 ture to animal matter, and which is the substance that 
 gives to wheat its superiority over other grain. The 
 next in order as to nourishing power is oil, then sugar, 
 then farina; and last of all gelatinous and extractive 
 matters. Simple tests of the relative nourishing pow- 
 ers of the different species of food, are the relative 
 quantities of these substances that they afford by ana- 
 lysis ; and though taste and appearance must influence 
 the consumption of all articles in years of plenty, yet 
 they are less attended to in times of scarcity, and on 
 such occasions this kind of knowledge may be of the 
 greatest importance. Sugar and farina or starch, are 
 very similar in composition, and are capable of being 
 converted into each other by simple chemical processes. 
 In the discussion of their relations, 1 shall detail to you 
 the results of some recent experiments, which will be 
 found possessed of applications both to the economy of 
 vegetation, and to some important processes of manu- 
 fjicture. 
 
 All the varieties of substances found in plants, are 
 produced from the sap, and the sap of plants is de- 
 rived from water, or from the fluids in the soil, and it 
 is altered by, or combined with principles derived from 
 the atmosphere. The influence of tlie soil, of water, 
 and of air, will therefore be the next subject of consid- 
 
15 
 
 eration. Soils in all cases consist of a mixture of dif- 
 ferent finely divided earthy matters ; with animal or 
 vegetable substances in a state of decomposition, and 
 certain saline ingredients. The earthy matters are 
 the true basis of the soil ; the other parts, whether na- 
 tural, or artificially introduced, operate in the same 
 manner as manures. Four earths generally abound in 
 soils, the aluminous, the siliceous, the calcareous, and 
 the magnesian. These earths, as I have discovered, 
 consist of highly inflammable metals united to pure air 
 or oxygene ; and they are not, as far as we know, de- 
 composed or altered in vegetation. 
 
 The great use of the soil is to afford support to the 
 plant, to enable, it to fix its roots, and to derive nourish- 
 ment by its tubes slowly and gradually, from the solu- 
 ble and dissolved substance mixed with the earths. 
 
 That a particular mixture of the earths is connected 
 with fertility, cannot be doubted: and almost all ste- 
 rile soils are capable of being improved, by a modifica- 
 tion of their earthy constituent parts. I shall describe 
 the simplest method as yet discovered of analysing soils, 
 and of ascertaining the constitution and chemical ingre- 
 dients which appear to be connected with fertility ; and 
 on this subject many of the former difiiculties of inves- 
 tigation will be found to be removed by recent inquiries. 
 
 The necessity of w^ater to vegetation, and the luxu- 
 riancy of the growth of plants connected with the pre- 
 sence of moisture in the southern countries of the old 
 continent, led to the opinion so prevalent in the earl^'^ 
 schools of philosophy, that water was the great produc- 
 tive element, the substance from which all things were 
 capable of being composed, and into which they were 
 finally resolved. The ^<^a6^<o-Tev ,m,£» w'^^^" of the poet, 
 '^ water is the noblest," seems to have been an expres- 
 sion of this opinion, adopted by the Greeks from the 
 Egyptians, taught by Thales, and revived by the al- 
 chemists in late times. Van Helmont in 1610, con- 
 ceived that he had proved by a decisive experiment, 
 that all the products of vegetables were capable of be- 
 ing generated from water. His results were shewn to 
 be fallacious by Woodward in 1691 ; but tlie true use 
 
16 
 
 of water in vegetation was unknown till 1785 ; when 
 Mr. Cavendish made the grand discovery, that it was 
 composed of two elastic fluids or gases, inflammable 
 gas or hydrogene, and vital gas or oxygene. 
 
 Air, like water, was regarded as a pure element by 
 most of the ancient philosophers : a few of the chemi- 
 cal inquirers in the sixteenth and seventeenth centuries, 
 formed some happy conjectures respecting its real na- 
 ture. Sir Kenelm Digby in 1660, supposed that it con- 
 tained some saline matter, which was an essential food 
 of plants. Boyle, Hooke, and Mayow, between 1665 
 and 1680, stated, that a small part of it only was con- 
 sumed in the respiration of animals, and in the combus- 
 tion of inflammable bodies ; but the true statistical ana- 
 lysis of the atmosphere is comparatively a recent la- 
 bour, acheived towards the end of the last century by 
 Scheele, Priestley, and Lavoisier. These celebrated 
 men shewed that its principal elements are two gases, 
 oxygene and azote, of which the first is essential to 
 flame, and to the life of animals, and that it likewise 
 contains small quantities of aqueous vapour, and of car- 
 bonic acid gas ; and Lavoisier proved that this last body 
 is itself a compound elastic fluid, consisting of charcoal 
 dissolved in oxygene. 
 
 Jethro Tull, in his treatise on Horse- hoeing, publish- 
 ed in 1733, advanced the opinion that minute earthy 
 particles supplied the whole nourishment of the vege- 
 table world ; that air and water were chiefly useful in 
 producing these particles from the land ; and that ma- 
 nures acted in no other way than in ameliorating the 
 texture of the soil, in short, that their agency was me- 
 chanical. Tliis ingenious author of the new system of 
 agriculture having observed the excellent effects pro- 
 duced in farming by a minute division of the soil, and 
 the pulverisation of it by exposure to dew and air, was 
 misled by carrying his principles too fjir. JJuhamcl, in 
 a work printed in 1754, adopted tlic opinion of Tull, 
 and stated that by finely dividing the soil, any number 
 of crops might be raised in succession from the same 
 land. He atteinpted also to prove, by direct experi- 
 ments, that vegetables of every kind were capable of 
 
17 
 
 being raised without manure. This celebrated horti- 
 culturist lived, however, sulficiently long to alter his 
 opinion. The results of his later and most refined ob- 
 servations led him to the conclusion, that no single ma- 
 terial afforded the food of plants. The general expe- 
 rience of farmers had long before convinced the unpre- 
 judiced of the truth of the same opinion, and that ma- 
 nures were absolutely consumed in the process of vege- 
 tation. The exhaustion of soils by carrying off corn 
 crops from them, and the effects of feeding cattle on 
 lands, and of preserving their manure, offer familiar il- 
 lustrations of the principles ; and several philosophical 
 inquirers, particularly Hassenfratz and Saussure, have 
 shewn by satisfactory experiments, that animal and ve- 
 getable matters deposited in soils are absorbed by plants, 
 and become a part of their organized matter. But though 
 neither water, nor air, nor earth, supplies the whole of 
 the food of plants, yet they all operate in the process 
 of vegetation. The soil is the laboratory in which the 
 food is prepared. No manure can be taken up by roots 
 of plants unless water is present ; and water or its ele- 
 ments exist in all the products of vegetation. The ger- 
 mination of seeds does not take place without the pre- 
 sence of air of oxygene gas ; and in the sunshine 
 vegetables decompose the carbonic acid gas of the at- 
 mosphere, the carbon of which is absorbed, and be- 
 comes a part of their organized matter, and the oxygene 
 gas, the other constituent, is given off; and in conse- 
 quence of a variety of agencies, the economy of vege- 
 tation is made subservient to the general order of the 
 system of nature. 
 
 It is sliewn by various researches, that the constitu- 
 tion of the atmosphere has been always the same since 
 the time that it was first accurately analysed ; and this 
 must in a great measure depend upon tlie powers of 
 plants to absorb or decompose the putrifying or decay- 
 ing remains of animals and vegetables, and the gaseous 
 effluvia which they are constantly emitting. Carbonic 
 acid gas is formed in a variety of processes of ferment- 
 ation and combustion, and in the respiration of animals, 
 and as yet no other process is known in nature by which 
 it can be consumed, except vegetation. Animals pro- 
 
18 
 
 ducc a substance which appears to be a necessary food 
 of vegetables ; vegetables evolve a principle necessary 
 to the existence of animals ; and these different classes 
 of beings seem to be thus connected together in the ex- 
 ercise of tlieir living functions, and to a certain extent 
 made to depend upon each other for their existence. 
 Water is raised from the ocean, diffused through the air, 
 and poured down upon the soil, so as to be applied to 
 the purposes of life. The different parts of the atmos- 
 phere are mingled together by winds or changes of tem- 
 perature, and successively brought in contact with the 
 surface of the earth, so as to exert their fertilizing in- 
 fluence. Tlie modifications of the soil, and the appli- 
 cation of manures are placed within the power of man, 
 as if for the purpose of awakening his industry and of 
 calling forth his powers. 
 
 The theory of the general operation of the more com- 
 pound manures may be rendered very obvious by sim- 
 ple chemical principles ; but there is still much to be 
 discovered with regard to the best methods of render- 
 ing animal and vegetable substances soluble ; with re- 
 spect to the processes of decomposition, how they may 
 be accelerated or retarded, and the means of producing 
 the greatest effects from the tnaterials employed ; these 
 subjects will be attended to in the Lecture on Manures. 
 
 Plants are found by analysis to consist principally of 
 charcoal and aeriform matter. They give out by dis- 
 tillation volatile compounds, the elements of which are 
 pure air, inflammable air, coally matter, and azote, or 
 that elastic substance which forms a great part of the 
 atmosphere, and which is incapable of supporting com- 
 bustion. These elements they gain either by their 
 leaves from the air, or by their roots from the soil. All 
 manures from organized substances contain the princi- 
 ples of vegetable matter, which during putrefaction are 
 rendered either soluble in water or aeriform — and in 
 these states they are capable of being assimilated to the 
 vegetable organs. 'No one principle affords the pabu- 
 lum of vegetable life ; it is neither charcoal nor hydro- 
 gene, nor azote nor oxygene alone ; but all of them to- 
 gether in various states and various combinations. Or- 
 ^auic substances as soon as they are deprived of vitality, 
 
19 
 
 begin to pass through a series of changes which ends 
 in their complete destruction, in the entire separation 
 and dissipation of the parts. Animal matters are the 
 soonest destroyed by the operation of air, heat, and 
 light. Vegetable substances yield more slowly, but 
 finally obey the same laws. The periods of the appli- 
 cation of manures from decomposing animal and vege- 
 table substances depend upon the knowledge of these 
 principles, and I shall be able to produce some new 
 and important facts founded upon them, which I trust 
 will remove all doubt from this part of agricultural theory. 
 
 The chemistry of the more simple manures ; the ma- 
 nures which act in very small quantities, such as gyp- 
 sum, alkalies, and various saline substances, has hither- 
 to been exceedingly obscure. It has been generally 
 supposed that these materials act in the vegetable econo- 
 my in the same manner as condiments or stimulants in 
 the animal economy, and that they render the common 
 food more nutritive. It seems, however, a much more 
 probable idea, that they are actually a part of the true 
 food of plants, and that they supply that kind of mat- 
 ter to the vegetable fibre, which is analogous to the bony 
 matter in animal structures. 
 
 The operation of gypsum, it is well known, is ex- 
 tremely capricious in this country, and no certain data 
 have hitherto been offered for its application. 
 
 There is, however, good ground for supposing that 
 the subject will be fully elucidated by chemical inquiry. 
 Those plants which seem most benefited by its appli- 
 cation, are plants which always afford it on analysis. 
 Clover, and most of the artificial grasses, contain it, 
 but it exists in very minute quantity only in barley, 
 wheat, and turnips. Many peat ashes which are sold 
 at a considerable price, consist in great part of gypsum, 
 with a little iron, and the first seems to be their most 
 active ingredient. I have examined several of the soils 
 to which these ashes are successfully applied, and I 
 have found in them no sensible quantity of gypsum. 
 In general, cultivated soils contain sufficient of this 
 substance for the use of the grasses : in such casfis, its 
 application cannot be advantageous. For plants re- 
 
20 
 
 f[iiii'e only a fertain quantity of raanure ; an excess 
 may be detrimental, and cannot be useful. 
 
 *i''lie theory of the operation of alkaline substances, 
 is one of the parts of the chemistry of agriculture, most 
 simple and distinct. They are found in all plants, and 
 therefore may l)e regarded as amongst their essential 
 ingredients. From their powers of combination like- 
 wise, they may be useful in introducing vaiious princi- 
 ples into tiie sap of vegetables, which may be subservient 
 to their nourishment. 
 
 The fixed alkalies which were formerly regarded as 
 elementary bodies, it has been my good fortune to de- 
 compose. They consist of pure air, united to highly 
 inflammable metallic substances ; but there is no reason 
 to suppose that they are reduced into their elements in 
 any of the processes of vegetation. 
 
 In this part of the Course I shall dwell at considera- 
 ble length on the important subject of Lime, and I shall 
 be able to oflPer some novel views. 
 
 Slacked lime was used by the Romans for manuring 
 the soil in which fruit trees grew. This we are inform- 
 ed by Pliny. Marie had been employed by the Bri- 
 tons and the Gauls from the earliest times, as a top 
 dressing for land. But the precise period in which 
 burnt lime first came into general use in the cultivation 
 of land, is, 1 believe, unknown. The origin of the ap- 
 plication from the early practices is sufficiently obvious; 
 a substance which has been used with success in gar- 
 dening, must have been soon tried in farming; and in 
 countries where marie was not to be found, calcined 
 limestone would be naturally employed as a substitute. 
 
 The elder writers on agricultin-e had no correct no- 
 tions of the nature of lime, limestone and marie, or of 
 their effects ; and this was the necessary consequence 
 of the imperfection of the chemistry of the age. Cal- 
 careous matter was considered by the alchemists as a 
 peculiar earth, which in the fire became combined with 
 inflammable acid ; and Evelyn and Hartlib, and, still 
 later, Lisle, in their works on husbandry, have charac- 
 terized it merely as a hot manure of use in cold lands. 
 It is to Dr. Black of Edinburgh that our first distinct 
 
21 
 
 rudiments of knowledge on the subject, are owing. 
 About the year 1755, this celebrated professor proved, 
 by the most decisive experiments, that limestone and 
 all its modifications, marbles, chalks, and marles, con- 
 sist principally of a peculiar eartli united to an aerial 
 acid : that the acid is given out in burning, occasioning 
 a loss of more than 40 per cent., and that the lime in 
 consequence becomes caustic. 
 
 These important facts immediately applied with equal 
 certainty to the explanation of the uses of lime, both as 
 a cement and as a manure. As a cement, lime applied 
 in its caustic state acquires its hardness and durability, 
 by absorbing the aerial (or as it has been since called 
 carbonic) acid, which always exists in small quantities 
 in the atmosphere, it becomes as it were again limestone. 
 
 Chalks, calcareous marles, or powdered limestone, 
 act merely by forming a useful earthy ingredient of the 
 soil, and their efBcacy is proportioned to the deficiency 
 of calcareous matter, which in larger or smaller quanti- 
 ties seems to be an essential ingredient of all fertile 
 soils ; necessary perhaps to tlieir proper texture, and as 
 an ingredient in the organs of plants. 
 
 Burnt lime, in its first effect, acts as a decomposing 
 agent upon animal or vegetable matter, and seems to 
 bring it into a state on which it becomes more rapidly 
 a vegetable nourishment ; gradually, however, the lime 
 is neutralized by carbonic acid, and converted into a 
 substance analogous to chalk ; but in this case it more 
 perfectly mixes with the other ingredients of the soil, 
 is more generally diffused and finely divided : and it is 
 probably more useful to land than any calcareous sub- 
 stance in its natural state. 
 
 The most considerable fact made known with regard 
 to limestone within the last few years, is owing to Mr. 
 Tennant. It had been long known that a particular 
 species of limestone found in different parts of tlie 
 North of England, when applied in its burnt and slack- 
 ed state to land in considerable quantities, occasioned 
 sterility, or considerably injured the crops for many 
 years. Mr. Tennant in 1800, by a chemical examina- 
 tion of this species of limestone, ascertained, that it 
 differed from common limestones by containing magne- 
 
22 
 
 sian earth ; and by several experiments he proved tliat 
 this earth was prejudicial to vegetation, when applied 
 in large quantities in its caustic state. Under common 
 circumstances the lime from the magnesian limestone is, 
 however, used in moderate quantities upon fertile soils 
 in Leicestershire, Derbyshire, and Yorkshire, with good 
 effect ; and it may be applied in greater quantities to 
 soils containing very large proportions of vegetable 
 matter. Magnesia when combined with carbonic acid 
 gas, seems not to be prejudicial to vegetation, and in 
 soils rich in manure, it is speedily supplied with this 
 principle from the decomposition of the manure. 
 
 After this nature and operation of manures have been 
 discussed, the next and the last subject for our conside- 
 ration, will be some of the operations of husbandry 
 capable of elucidation by chemical principles. 
 
 The cliemical theory of fallowing is very simple. 
 Fallowing affords no new source of riches to the soil. 
 It merely tends to produce an accumulation of decom- 
 posing matter, which in the common course of crops 
 would be employed as it is formed, and it is scarcely 
 possible to imagine a single instance of a cultivated soil, 
 which can be supposed to remain fallow for a year with 
 advantage to the farmer. The only cases where this 
 practice is beneficial seems to be in the destruction of 
 weeds, and for cleansing foul soils. 
 
 The chemical theory of paring and burning, I shall 
 discuss fully in this part of the Course. 
 
 It is obvious that in all cases it must destroy a certain 
 quantity of vegetable matter, and must be principally 
 useful in cases in which there is an excess of this mat- 
 ter in soils. Burning, likewise renders clays less co- 
 herent, and in this way greatly improves their texture, 
 and causes them to be less permable to water. 
 
 The instances in which it must be obviously prejudi- 
 cial, are those of sandy dry siliceous soils, containing 
 little animal or vegetable matter. Here it can only be 
 destructive, for it decomposes that on which the soil de- 
 pends for its productiveness. 
 
 The advantages of irrigation, though so lately a sub- 
 ject of much attention, were well known to the ancients ; 
 and more than two centuries ago the practice was re- 
 
26 
 
 commended to the farmers of our country by Lord Ba- 
 con ; " meadow-watering," according to the statements 
 of this illustrious personage, (given in his Natural His- 
 tory, in the article Vegetation,) acts not only by sup- 
 plying useful moisture to the grass ; but likewise the 
 water carries nourishment dissolved in it, and defends 
 the roots from the effects of cold. 
 
 No general principles can be laid down respecting 
 vthe comparative merit of the different systems of culti- 
 vation, and the different systems of crops adopted in 
 different districts, unless the chemical nature of the soil, 
 and the physical circum*stances to which it is exposed 
 are fully known. Stiff coherent soils are those most 
 benefited by minute division and aeration, and in the 
 drill system of husbandry, these effects are produced 
 to the greatest extent ; but still the labour and expense 
 connected with its application in certain districts, may 
 not be compensated for by the advantages produced. 
 Moist climates are best fitted for raising the artificial 
 grasses, oats, and broad-leaved crops ; stiff aluminous 
 soils, in general, are most adapted for wheat crops, and 
 calcareous soils produce excellent sain-foin and clover. 
 
 Nothing is more wanting in agriculture, than experi- 
 ments in which all the circumstances are minutely and 
 scientifically detailed. This art will advance with ra- 
 pidity in proportion as it becomes exact in its methods. 
 As in physical researches all the causes should be con- 
 sidered ; a difference in the results may be produced, 
 even by the fall of a half an inch of rain more or less 
 in the course of a season, or a few degrees of tempera- 
 ture, or even by a slight difference in the sub-soil, or in 
 the inclination of the land. 
 
 Information collected after views of distinct inquiry, 
 would necessarily be more accurate, and more capable 
 of being connected with the general principles of 
 science ; and a few histories of the results of truly phi- 
 losophical experiments in agricultural chemistry, would 
 be of more value in enlightening and benefiting the far- 
 mer, than the greatest possible accumulation of imper- 
 fect trials conducted merely in the empirical spirit. It 
 is no unusual occurrence for persons who argue in fa- 
 vour of practice and experience, to condemn generally 
 
24 
 
 all attempts to improve agi-iculture by philosophical in- 
 quiries and chemical methods. That much vague spe- 
 culation may be found in the works of those who have 
 lightly taken up agricultural chemistry, it is impossible 
 to deny. It is not uncommon to find a number of chan- 
 ges rung upon a string of technical terms, such as oxy- 
 gene, hydrogene, carbon, and azote, as if the science de- 
 pended upon words, rather than upon things. But this 
 is in fact an argument for the necessity of the establish- 
 ment of just principles of chemistry on the subject. 
 Whoever reasons upon agriculture, is obliged to recur 
 to this science. He feels that it is scarcely possible to 
 advance a step without it : and if he is satisfied witli 
 insuflficient views, it is not because he prefers them to 
 accurate knowledge, but generally because they are 
 more current. If a person journeying in the night 
 wishes to avoid being led astray by the ignis fatuus, 
 the most secure method is to carry a lamp in his own 
 hand. 
 
 It has been said, and undoubtedly with great truth, 
 that a philosophical chemist would most probably make 
 a very unprofitable business of farming ; and this cer- 
 tainly would be the case, if he were a mere philosophical 
 chemist ; and unless he had served his apprenticeship 
 to the practice of the art, as well as the theory. But 
 there is reason to believe, that lie would be a more suc- 
 cessful agriculturist than a person equally uninitiated 
 in farming, but ignorant of chemistry altogether ; his 
 science, as far as it went, would be useful to him. But 
 chemistry is not the only kind of knowledge required, 
 it forms a small part of the philosophical basis of agri- 
 culture ; but it is an important part, and whenever ap- 
 plied in a proper manner must produce advantages. 
 
 In proportion as science advances all the principles 
 become less complicated, and consequently more useful. 
 And it is then that their application is most advanta- 
 geously made to the arts. The common labourer can 
 never be enlightened by the general doctrines of phi- 
 losophy, but he will not refuse to adopt any practice, of 
 the utility of which he is fully convinced, because it 
 has been founded upon tliese principles. The mariner 
 can trust to the compass, though he may be wholly un- 
 
25 
 
 acquainted with the discoveries of Gilbert on masjuet- 
 ism, or the refined principles of tliat science developed 
 by the genius of jEpinus. The dyer will use his bleach- 
 ing liquor, even though he is perhaps ignorant not only 
 of the constitution, but even of the name of the sub- 
 stance on which its powers depend. The great pur- 
 pose of chemical investigation in Agriculture, ought un- 
 doubtedly to be the discovery of improved methods of 
 cultivation. But to this end, general scientific princi- 
 ples and practical knowledge, are alike necessary. The 
 germs of discovery are often found in rational specula- 
 tions ; and industry is never so efficacious as when as- 
 sisted by science. 
 
 It is from the higher classes of the community, from 
 ihe proprietors of land ; those who are fitted ])y their 
 education to form enlightened plans, and by their for- 
 tunes to carry such plans into execution ; it is from these 
 that the principles of improvement must flow to the la- 
 bouring classes of the community ; and in all cases the 
 benefit is mutual ; for the interest of the tenantry must 
 be always likewise the interest of the proprietors of 
 the soil. The attention of the labourer will be more 
 minute, and he will exert himself more for improve- 
 ment when he is certain he cannot deceive his employ- 
 er, and has a conviction of the extent of hii^ knowledge. 
 Ignorance in the possessor of an estate of the manner 
 in which it ought to be treated, generally leads either 
 to inattention or injudious practices in the tenant or the 
 bailiff. ^^ Agnun pessimum mulctari cujus Dominus 
 non docet sed audit vUliciim.^^ 
 
 There is no idea more unfounded than that a great 
 devotion of time, and a minute knowledge of general 
 chemistry is necessary for pursuing experiments on the 
 nature of soils or the properties of manures. Nothing 
 can be more easy than to discover whether a soil effer- 
 vesces, or changes colour by the action of an acid, or 
 whether it burns when heated ; or what weight it loses 
 by heat : and yet these simple indications may ])e of 
 great importance in a system of cultivation. Tlie ex- 
 pense connected with chemical inquiries is extremely 
 trifling ; a small closet is sufficient for containing all the 
 materials required. The most important experiments 
 may be made by means of a small portable apparatus ; 
 
 D 
 
26 
 
 a few phials, a few acids, a lamp and a crucible are all 
 that are necessary, as I shall endeavour to prove to you, 
 in the course of these lectures. 
 
 It undoubtedly happens in agricultural chemical ex- 
 periments conducted after the most refined theoretical 
 views, that there are many instances of failure, for one 
 of success ; and this is inevitable from the capricious 
 and uncertain nature of the causes that operate, and 
 from the impossibility of calculating on all the circum- 
 stances that may interfere ; but this is far from proving 
 the inutility of such trials ; one happy result which can 
 generally improve the methods of cultivation is worth the 
 labour of a whole life ; and an unsuccessful expertiment 
 well observed, must establish some truth, or tend to re- 
 move some prejudice. 
 
 Even considered merely as a philosophical science, 
 this department of knowledge is highly worthy of cul- 
 tivation. For what can be more delightful than to trace 
 the forms of living beings and their adaptations and pe- 
 culiar purposes ; to examine the progress of inorganic 
 matter in its different processes of change, till it attain 
 its ultimate and highest destination ; its subserviency to 
 the purposes of man. 
 
 Many of the sciences are ardently pursued, and con- 
 sidered as proper objects of study for all refined minds, 
 merely on account of the intellectual pleasure they af- 
 ford ; merely because they enlarge our views of nature, 
 and enable us to think more correctly with respect to 
 the beings and objects surrounding us. How much 
 more then is this department of inquiry worthy of at- 
 tention, in which the pleasure resulting from the love 
 of truth and of knowledge is as great as in any other 
 branch of philosophy, and in which it is likewise con- 
 nected with much greater practical benefits and advan- 
 tages. " JSTihil est melius, nihil uherius, nihil homine 
 libero dignius.^^ 
 
 Discoveries made in the cultivation of the earth, are 
 not merely for the time and country in which they are 
 developed, but they may be considered as extending to 
 future ages, and as ultimately tending to benefit the 
 w hole human race : as affording subsistence for genera- 
 tions yet to come ; as multiplying life, and not only 
 multiplying life, but likewise providing for its enjoyment. 
 
LECTURK II 
 
 Of the general Powers of Matter which influence Ve- 
 getation. Of Gravitation, of Cohesion, of Chemical 
 Attraction, of Heat, of Light, of Electricity, ponder- 
 able Substances, Elements of Matter, particularly 
 those found in Vegetables, Laws of their Combina- 
 tions and ^Arrangements. 
 
 A HE great operations of the farmer are directed to- 
 wards the production or improvement of certain classes 
 of vegetables ; they are either mechanical or chemical, 
 and are, conse(3[uently, dependent upon the laws which 
 govern common matter. Plants themselves are, to a 
 certain extent, submitted to these laws ; and it is neces- 
 sary to study their effects, both in considering the phse- 
 nomena of vegetation, and the cultivation of the vege- 
 table kindom. 
 
 One of the most important properties belonging to 
 matter is gravitation, or the power by wiiich masses of 
 matter are attracted towards each other. It is in con- 
 sequence of gravitation that bodies thrown into the at- 
 mosphere fall to the surface of the earth, and that the 
 different parts of the globe are preserved in their pro- 
 per positions. Gravity is exerted in proportion to the 
 quantity of matter. Hence all bodies placed above the 
 surface of the earth fall to it in right lines, which if 
 produced would pass through its centre ; and a body 
 falling near a high mountain, is a little bent out of the 
 perpendicular direction by the attraction of the moun- 
 tain, as has been shewn by the experiments of Dr. Mas- 
 kelyne on Schehallien. 
 
 Gravitation has a very important influence on the 
 growth of plants ; and it is rendered probable, by the 
 experiments of Mr. Knight, that they owe the peculiar 
 direction of their roots and branches almost entirely to 
 this force. 
 
 That gentleman fixed some seeds of the garden bean 
 
2.8 
 
 oil ilie circnmrereiicft of a wheel, which in one instance 
 was placed vertically, and in the other horizontally, 
 and made to revolve, by means of another wheel work- 
 ed hj water, in such a manner, that the number of the 
 revolutions could be regulated ; the beans were supplied 
 witli moisture, and were placed under circumstances fa- 
 vourable to germination. The greatest velocity of mo- 
 tion given to the wheel was such, that it performed two 
 hundred and fifty revolutions in a minute. It was found 
 that in all cases the beans grew, and that the direction 
 of the roots and stems was influenced by the motion of 
 the wheel. When the centrifugal force was made su- 
 perior to tlie force of gravitation, which was supposed 
 to l)e done when the vertical Mheel performed 150 re- 
 vi)lutions in a minute, all the radicles, in whatever way 
 they were protruded from the position of the seeds, 
 turned their points outwards from the circumference of 
 the wheel, and in their subsequent growth receded near- 
 ly at right angles from its axis ; the germens, on the 
 contrary took the opposite direction, and in a few days 
 their points all met in the centre of the wheel. 
 
 When the centrifugal force was made merely to mo- 
 dify the force of gravitation in the horizontal wheel, 
 where the greatest velocity of revolution was given, the 
 radicles pointed downwards about ten degrees below, 
 and the germens as many degrees above the horizontal 
 line of the wheel's motion ; and the deviation from the 
 perpendicular was less in proportion, as the motion was 
 less rapid.* 
 
 These facts afford a rational solution of this curious 
 problem, respecting wliich different philosophers have 
 given such different opinions ; some referring it to the 
 nature of the sap, as De la Hire, others, as Darwin, to 
 the living powers of the plant, and the stimulus of air 
 upon the leaves, and of moisture upon the roots. The 
 effect is now shewn to be connected with mechanical 
 causes ; and there seems no other power in nature to 
 which it can Avith propriety be referred but gravity, 
 
 * Fig. I, represents the form of the experiment vhen the horizon- 
 tal wheel was made to peHorm 250 revolutions in a minute. 
 
 fig. 2, represents the case in which the vertical wheel performed 
 150 revolutions. 
 
29 
 
 which acts uuiversally, and wliich must tend to dispose 
 the parts to take a uniform direction. 
 
 If plants in general owe their perpendicular direction 
 to gravity, it is evident that the number of plants upon 
 a given part of the earth's circumference, cannot be in- 
 creased by making the surface irregular, as some per- 
 sons have supposed. Nor can more stalks rise on a 
 hill than on a spot equel to its base ; for the slight ef- 
 fect of the attraction of the hill, would be only to make 
 the plants deviate a- very little from the perpendicular. 
 Where horizontal layers are pushed forth, as in certain 
 grasses, particularly such as the fiorin, lately brought 
 into notice by Dr. Richardson, more food may, however, 
 be produced upon an irregular surface ; but the princi- 
 ple seems to apply strictly to corn crops. 
 
 The direction of the radicles and germens is such, 
 that both are supplied with food, and acted upon by 
 those external agents which are necessary for their de- 
 velopment and growth. The roots come in contact with 
 the fluids in the ground; the leaves arc exposed to 
 light and air ; and the same grand law which preserves 
 the planets in their orbits, is thus essential to the func- 
 tions of vegetable life. 
 
 When two pieces of polished glass are pressed to- 
 gether they adhere to each otlier, and it requires some 
 force to separate them. This is said to depend upon 
 the attraction of cohesion. The same attraction gives 
 the globular form to drops of water, and enables fluids 
 to rise in capillary tubes ; and hence it is sometimes 
 called cajjillary attraction. This attraction, like gravi- 
 tation, seems common to all matter, and may be a mo- 
 dification of the same general force ; like gravitation, 
 it is of great importance in vegetation. It preserves the 
 forms of aggregation of the parts of plants, and it seems 
 to be a principal cause of the absorptions of fluids by 
 their roots. 
 
 If some pure magnesia, the calcined magnesia of 
 druggists, be thrown into distilled vinegar, it gradually 
 dissolves. This is said to be owing to chemical attrac- 
 tion^ the power by which difierent species of matter 
 tend to unite into one compound. Various kinds of 
 matter unite with different deirrees of force : tlins sul- 
 
phuric acid and magnesia unite with more readiness 
 than distilled vinegar and magnesia ; and if sulphuric 
 acid be poured into a mixture of vinegar and magnesia, 
 in which the acid properties of the vinegar have been 
 destroyed by the magnesia, the vinegar will be set free, 
 and the sulphuric acid will take its place. This chemi- 
 cal attraction is likewise called chemical affinity. It is 
 active in most of the phaenomena of vegetation. The 
 sap consists of a number of ingredients, dissolved in 
 water by chemical attraction ; and it appears to be in 
 consequence of the operation of this power, that certain 
 principles derived from the sap are united to the vege- 
 table organs. By the laws of chemical attraction, dif- 
 ferent products of vegetation are changed, and assume 
 new forms ; the food of plants is prepared in the soil ; 
 vegetable and animal remains are changed by the ac- 
 tion of air and Avater, and inade fluid or aeriform ; rocks 
 are broken down and converted into soils ; and soils 
 are more finely divided and fitted as receptacles for the 
 roots of plants. 
 
 The different powers of attraction tend to preserve 
 the arrangements of matter, or to unite them in new 
 forms. If there were no opposing powers, there would 
 soon be a state of perfect quiescence in nature, a kind 
 of eternal sleep in the physical world. Gravitation is 
 continually counteracted by mechanical agencies, by 
 projectile motion, or the centrifugal force; and their 
 joint agencies occasion the motion of the heavenly bodies. 
 Cohesion and chemical attraction are opposed by the 
 repulsive energy of heat, and the harmonious cycle of 
 terrestrial changes is produced by their mutual operations. 
 
 Heat is capable of being communicated from one body 
 to other bodies ; and its common effect is to expand 
 them, to enlarge them in all their dimensions. This is 
 easily exemplified. A solid cylinder of metal after be- 
 ing heated will not pass through a ring barely sufficient 
 to receive it when cold. When water is heated in a globe 
 of glass having a long slender neck, it rises in the neck ; 
 and if heat be applied to air confined in such a vessel 
 inverted above water, it makes its escape from the ves- 
 sel and passes through the water. Thermometers are 
 instruments for measuring degrees of heat by the ex- 
 
p. 5C> 
 
pausion of iiuids in narrow tubes. Mercury is general- 
 ly used, of which 100,000 parts at the freezing point of 
 water become 101,835 parts at the boiling point, and on 
 Fahrenheit's scale these parts are divided into 180 de- 
 grees. Solids, by a certain increase of heat, become 
 fluids, and fluids gases, or elastic fluids. Thus ice is 
 converted by heat into water, and by still more heat it 
 becomes steam : and heat disappears, or, as it is called, 
 is rendered latent during the conversion of solids into 
 fluids, or fluids Jinto gases, and re- appears or becomes 
 sensible when gases become fluids, or fluids solids : 
 lience cold is produced during evaporation, and heat 
 during the condensation of steam. 
 
 There are few exceptions to the law of expansion of 
 bodies by heat, which seem to depend either upon some 
 change in their chemical constitution, or on their be- 
 coming crystallized. Clay contracts by heat, which 
 seems to be owing to its giving off water. Cast iron and 
 antimony, when melted, crystallize in cooling and ex- 
 pand. Ice is much lighter than water. Water expands 
 a little even before it freezes, and it is of the greatest 
 density at about 41® or 42*^, the freezing point being 
 32® ; and this circumstance is of considerable importance 
 in the general economy of nature. The influence of the 
 changes of seasons and of the position of the sun on the 
 phenomena of vegetation, demonstrates the effects of heat 
 on the functions of plants. The matter absorbed from 
 the soil must be in a fluid state to pass into their roots, 
 and when the surface is frozen they can derive no nou- 
 rishment from it. The activity of chemical changes like- 
 wise is increased by a certain increase of temperature, 
 and even the rapidity of the ascent of fluids by capilla- 
 ry attraction. 
 
 This last fact is easily shewn by placing in each of 
 two wine glasses a similar hollow stalk of grass, so bent 
 as to discharge any fluid in the glasses slowly by capil- 
 lary attraction ; if hot water be in one glass, and cold 
 water in the other, the hot water will be discharged 
 much more rapidly than the cold water. The fermen- 
 tation and decomposition of animal and vegetable sub- 
 stances require a certain degree of heat, which is conse- 
 quently necessary for the preparation of the food of 
 
32 
 
 plants ; and as evaporation is more rapid in proportion 
 as the temperature is higher, the superfluous parts of the 
 sap are most readily carried oflf at the time its ascent is 
 quickest. 
 
 Two opinions are current respecting the nature of 
 heat. By some philosophers it is conceived to be a pe- 
 culiar subtle fluid, of which the particles repel each other, 
 but have a strong attraction for the particles of other 
 matter. By others it is considered as a motion or vibra- 
 tion of the particles of matter, which is supposed to dif- 
 fer in velocity in different cases^ and thus to produce the 
 different degrees of temperature. Whatever decision be 
 ultimately made respecting these opinions, it is certain 
 that there is matter moving in tlie space between us and 
 the heavenly bodies capable of communicating heat; the 
 motions of which are rectilineal : thus the solar rays pro- 
 duce heat in acting on the surface of the earth. The 
 beautiful experiments of Dr. Herschel have shewn that 
 there are rays transmitted from the sun which do not il* 
 luminate ; and which yet produce more heat than the vi- 
 sible rays; and Mr. Ritter and Dr. Wollaston have 
 shewn that there are other invisible rays distinguished 
 by their chemical effects. 
 
 The different influence of the different solar rays on 
 vegetation have not yet been studied ; but it is certain 
 that the rays exercise an influence independent of the 
 heat they produce. Thus plants kept in the dark in a 
 hot-house grow luxuriantly, but they never gain their 
 natural colours ; their leaves are white or pale, and their 
 juices watery and peculiarly saccharine. 
 
 When a piece of sealing- wax is rubbed by a woollen 
 cloth, it gains the power of attracting light bodies, such 
 as feathers or ashes. In this state it is said to be elec- 
 trical; and if a metallic cylinder, placed upon a rod of 
 glass, is brought in contact with the sealing-wax, it like- 
 wise gains the momentary poAver of attracting light bo- 
 dies, so that electricity, like heat, is communicable. 
 When two light bodies receive the same electrical in- 
 fluence, or are electrified by the same body, they repel 
 each other. When one of them is acted on by sealing- 
 wax, and the other by glass that has been rubbed by 
 woollen, they attract each other : hence it is said, that 
 
33 
 
 bodies similarly electrified repel each other, and bodies 
 dissimilarly electrified attract each other: and the elec- 
 tricity of glass is called vitreous or positive electricity,* 
 and that of sealing-wax resinous or negative electri- 
 city. 
 
 When of two bodies made to rub each other one is 
 found positively electrified, the other is always found 
 negatively electrified, and, as in the common electrical 
 machine, these states are capable of being communica- 
 ted to metals placed upon rods or pillars of glass. Elec- 
 tricity is produced likewise by the contact of bodies ; 
 thus a piece of zinc and of silver give a slight electri- 
 cal shock when they are made to touch each other, and 
 to touch the tongue : and when a number of plates of 
 copper and zinc, 100 for instance, are arranged in a pile 
 with cloths moistened in salt and water, in the order of 
 zinc, copper, moistened cloth, zinc, copper, moistened 
 cloth, and so on, they form an electrical battery which will 
 give strong shocks and sparks, and which is possessed 
 of remarkable chemical powers. The luminous phseno- 
 mena produced by common electricity are well known. 
 It would be improper to dwell upon them in this place. 
 They are the most impressive effects occasioned by this 
 agent; and they offer illustrations of lightning and thunder. 
 
 Electrical changes are constantly taking p]^ce in na- 
 ture, on the surface of the earth, and in the atmosphere ; 
 but as yet the eifects of this power in vegetation have 
 not been correctly estimated. It has been shewn by ex- 
 periments made by means of the Voltaic battery (the in- 
 struments composed of zinc, copper, and water) that com- 
 pound bodies in general are capable of being decompo- 
 sed by electrical powers, and it is probable, that the va- 
 rious electrical phsenoraena occurring in our system, 
 must influence both the germination of seeds and the 
 growth of plants. 1 found that corn sprouted mucii 
 more rapidly in water positively electrified by the Vol- 
 taic instrument, than in water negatively electrified ; and 
 experiments made upon the atmosphere shew that clouds 
 are usually negative ; and as when a cloud is in one state 
 of electricity, the surface of the earth beneath is brought 
 into the opposite state, it is probable that in common 
 cases the surface of the earth is positive, 
 
 £ 
 
34 
 
 l)ifferent opinions are enteitained amongst scientific 
 men respecting the nature of electricity ; by some, the 
 phaenoraena are conceived to depend upon a single sub- 
 tile fluid in excess in the bodies, said to be positively 
 electrified, in deficiency in tlie bodies said to be nega- 
 tively electrified. A second class suppose the effects to 
 be produced by two different fluids, called by them the 
 vitreous fluid and the resinous fluid ; and others regard 
 them as affections or motions of matter, or an exhibition 
 of attractive powers, similar to those which produce che- 
 mical combination and decomposition ; but usually ex- 
 erting their action on masses. 
 
 The different powers that have been thus generally 
 described, continually act upon common matter, so as to 
 change its form, and produce arrangements fitted for the 
 purposes of life. Bodies are either simple or compound. 
 A body is said to be simple, when it is incapable of be- 
 ing resolved into any other forms of matter. Thus gold, 
 or silver, though they may be melted by heat, or dissol- 
 ved in coi'rosive menstrua, yet are recovered unchanged 
 in their properties, and they are said to be simple bodies. 
 A body is considered as compound, when two or more 
 distinct substances are capable of being produced from 
 it ; thus marble is a compound body, for by a strong 
 heat, it is converted into lime, and an elastic fluid is dis- 
 engaged in the process : and the proof of our knowledge 
 of the true composition of a body is, that it is capable of 
 being reproduced by the same substances as those into 
 which is had been decomposed ; thus by exposing lime 
 for a long while to the elastic fluid, disengaged during 
 its calcination, it becomes converted into a substance si- 
 milar to powdered marble. The term element has the 
 same meaning as simple or undecompoundedbody; but 
 it is applied merely with reference to the present state 
 of chemical knowledge. It is probable, that as yet we 
 are not acquainted with any of the true elements of mat- 
 ter ; many substances, formerly supposed to be simple, 
 have been lately decompounded, and the chemical ar- 
 rangement of bodies must be considered as a mere ex- 
 pression of facts, the results of accurate statical experi- 
 ments. 
 
 Vegetable substances in general are of a very com- 
 
65 
 
 pound nature, and consist of a great number of elements, 
 most of which belong likewise to the other kingdoms of 
 nature, and are found in various form*. Their more 
 complicated arrangements are best understocd after 
 their simpler forms of combination have been examin- 
 ed. 
 
 The number of bodies which I shall consider as at 
 present undecomposed, are, as was stated in the intro- 
 ductory lecture, three acidifying and solvent substances, 
 six inflammable bodies, and thirty-eight metals. 
 
 In most of the inorganic compounds, the nature of 
 which is well known, into which these elements enter, 
 they are combined in definite proportions ; so that if the 
 elements be represented by numbers, the proportions in 
 which they combine are expressed either by those num- 
 bers, or by some simple multiples of them. 
 
 1 shall mention, in a few words, the characteristic 
 properties of the most important simple substances, and 
 the numbers representing the proportions in which they 
 combine in those cases, where they have been accurate- 
 ly ascertained. 
 
 1. Oxygene forms about one-fifth of the air of our at- 
 mosphere. It is an elastic fluid, at all known tempera- 
 tures. Its specific gravity is to that of air as 10967 to 
 10000. It supports combustion with much more vivid- 
 ness than common air ; so that if a small steel wire, or 
 a watch-spring, having a bit of inflamed wood attached 
 to it, be introduced into a bottle filled with the gas, it 
 burns with great splendour. It is respirable. It is 
 very slightly soluble in water. The number represent- 
 ing the proportion in which it combines is 15. It may 
 be made by heating a mixture of the mineral called man- 
 ganese, and sulphuric acid together, in a proper vessel, 
 or by heating strongly red lead, or red precipitate of 
 mercury. 
 
 2. Chlorine, or oxymuriatic gas, is, like oxygene, a 
 permanent elastic fluid. Its colour is yellowish green; 
 its smell is very disagreeable; it is not respirable ; it 
 supports the combustion of all the common inflammable 
 bodies except charcoal ; its specific gravity is to that of 
 air as 24677 to 10000; it is soluble in about half its vo- 
 lume of water, and its solution in water destroys vege- 
 
86 
 
 table colours. Many of the metals (such as arsenic uu 
 copper) take tire spontaneously when introduced into a 
 jar or bottle tilled with the gas. Chlorine may be pro- 
 cured by heating together a mixture of spirits of salt or 
 muriatic acid, and manganese. The number represent- 
 ing the proportion in which this gas enters into combi- 
 nation is 67. 
 
 3. Fluorine^ or the fluoric principle. This substance 
 has such strong tendencies of combination, that as yet, 
 no vessels have been found capable of containing it in 
 its pure form. It may be obtained combined with hy- 
 drogene, by applying heat to a mixture of fluor or Der- 
 byshire spar, and sulphuric acid, and in this state it is 
 an intensely acid compound, a little heavier than water, 
 and which becomes still denser by combining with wa- 
 ter. 
 
 4. Hydrogene, or inflammable air, is the lightest 
 known substance ; its specific gravity is to that of air as 
 732 to 10000. It burns by the action of an inflamed 
 taper, when in contact with the atmosphere. The pro- 
 portion in which it combines is represented by unity, 
 or 1. It is procured by the action of diluted oil of vi- 
 troil, or hydro-sulphuric acid on filings of zinc or iron. 
 it is the substance employed for filling air balloons. 
 
 5. Azote is a gaseous substance, not capable of being 
 condensed by any known degree of cold : its specific 
 gravity is to that of common air as 9516 to 10000. It 
 does not enter into combustion under common circum- 
 stances, but may be made to unite with oxygene by the 
 agency of electrical fire. It forms nearly four-fifths of 
 the air of the atmosphere ; and may be procured by 
 burning phosphorous in a confined portion of air. The 
 number representing the proportion in which it combines 
 is 26. 
 
 6. Carbon is considered as the pure matter of char- 
 coal, and it may be procured by passing spirits of wine 
 through a tube heated red. It has not yet been fused ; 
 but rises in vapour at an intense heat. Its specific gra- 
 vity cannot be easily ascertained ; but that of the dia- 
 mond, which cannot chemically be distinguished from 
 pure carbon, is to that of water as 3500 to 1000. Char- 
 coal has the remarkable property of absobing several 
 
a: 
 
 times its volume of cliff'erent elastic iluids, which are ca- 
 pable of being expelled from it by heat. The number 
 representing it is 11.4. 
 
 7. Sulphur is the pure substance so well known by 
 that name : its specific gravity is to that of water as 
 1990 to 1000. It fuses at about 220® Fahrenheit ; and 
 at between 500® and 600® takes fire, if in contact with 
 the air, and burns with a pale blue flame. In this pro- 
 cess it dissolves in the oxygene of the air, and produces 
 a peculiar acid elastic fluid. The number representing 
 it is 30. 
 
 8. PJiosphorus is a solid of a pale red colour, of spe- 
 cific gravity 1770. It fuses at 90°, and boils at 550®. 
 It is luminous in the air at common temperatures, and 
 burns with great violence at 150*>, so tliat it must be 
 handled with great caution. Tlie number represent- 
 ing it is 20. It is procured by digesting together bone 
 ashes and oil of vitroil, and strongly heating the fluid 
 substance so produced with powdered charcoal. 
 
 9. Boron is a solid of a dark olive colour, infusible 
 at any known temperature. It is a substance very late- 
 ly discovered, and procured from boracic acid. It burns 
 with brilliant sparks, when heated in oxygene, but not 
 in chlorine. Its specific gravity and the number repre- 
 senting it, are not yet accurately known. 
 
 10. Platinum is one of the noble metals, of rather 
 a duller white than silver, and the heaviest body in na- 
 ture ; its specific gravity being 21500. It is not acted 
 upon by any acid menstrua except such as contain 
 chlorine : it requires an intense degree of heat for its fu- 
 sion. 
 
 11. The properties of ^oMare well known. Its spe- 
 cific gravity is 19277. It bears the same relation to 
 acid menstrua as platinum : it is one of the characteris- 
 tics of both these bodies, that they are very difficultly 
 acted upon by sulphur. 
 
 12. Silver is of specific gravity 10400, it burns more 
 readily than platinum or gold, which require the intense 
 heat of electricity. It readily unites to sulphur. The 
 number representing it is 205. 
 
 13. Mercury is the only known metal fluid at the 
 common temperature of the atmosphere ; it boils at 660°, 
 
38 
 
 and freezes at 39 below 0. Its specific gravity is 13560 
 The number representing it is 380. 
 
 14. Copper is of specific gravity 8890. It burns when 
 strongly heated with red flame tinged with green. The 
 number representing it is 120. 
 
 15. Cobalt is of specific gravity 7700. Its point of 
 fusion is very high, nearly equal to that of iron. In its 
 calcined or oxidated state, it is employed for giving a 
 blue colour to glass. 
 
 16. JVickel is of a white colour : its specific gravity 
 is 8820. This metal and cobalt agree with iron, it be- 
 ing attractible by the magnet. The number representing, 
 nickel is 111. 
 
 17. Iron is of specific gravity 7700. Its other pro- 
 perties are well known. The number representing it 
 is 103. 
 
 18. Tin is of specific gravity 729 1 ; it is a very fusi- 
 ble metal, and burns when ignited in the air : the num- 
 ber representing the proportion in which it combines 
 is 110. 
 
 19. Zinc is one of the most combustible of the com- 
 mon metals. Its specific gravity is about 7210. It is 
 a brittle metal under common circumstances ; but when 
 heated may be hammered or rolled into thin leaves, and 
 after this operation is malleable. The number repre- 
 senting it is 68. 
 
 20. Lead is of specific gravity 11352; it fuses at a 
 temperature rather higher than tin. The number re- 
 presenting it is 398. 
 
 21. Bismuth is a brittle metal of specific gravity 
 9822. It is nearly as fusible as tin ; when cooled slow- 
 ly it crystallizes in cubes. The number representing 
 it is 135. 
 
 22. Antimony is a metal capable of being volatilized 
 by a strong heat. Its specific gravity is 6800. It burns 
 when ignited with a faict white light. The number re- 
 presenting it is 170. 
 
 23. Arsenic is of a bluish white colour, of specific 
 gravity 8310. It may be procured by heating the pow- 
 der of common w hite arsenic of the shops strongly in 
 a Florence flask with oil. The metal rises in vapour, 
 and condenses in the neck of the flask. The number 
 representing it is 90. 
 
a9 
 
 24. Manganesmn may be procured from the mineral 
 called manganese, by intensely igniting it in a forge 
 mixed with charcoal powder. It is a metal very diffi- 
 cult of fusion, and very combustible ; its specific gravi- 
 ty is 6850. The number representing it is 177. 
 
 25. Potassium is the lightest known metal, being 
 only of specific gravity 850. It fuses at about 150°, 
 and rises in vapour at a heat a little below redness. It 
 is a highly combustible substance, takes fire when 
 thrown upon water, burns with great brilliancy, and 
 the product of its combustion dissolves in the water, 
 The number representing it is 75. It may be made by 
 passing fused caustic vegetable alkali, the pure kali of 
 druggists, through iron turnings strongly ignited in a 
 gun barrel, or by the electrization of potash by a strong 
 Voltaic battery. 
 
 26. Sodium may be made in a similar manner to po- 
 tassium. Soda, or the mineral alkali, being substituted 
 for the vegetable alkali. It is of specific gravity 940. 
 It is very combustible. When thrown upon water, it 
 swims on its surface, hisses violently, and dissolves, 
 but does not inflame. The number representing it is 88. 
 
 27. Barium has as yet been procured only by elec- 
 trical powers and in verj' minute quantities, so that its 
 properties have not been accurately examined. The 
 number representing it appears to be 180. 
 
 Strontium the 28, Calcium the 29th, Magnesium 
 the 30th, Silicum the 31st, Muminiun the 32d, Zirco- 
 num the 33d, Glueinum the 34th, and Ittrium the 35th 
 of the undecompounded bodies, like barium, have either 
 not been procured absolutely pure, or only in such mi- 
 nute quantities that their properties are little known ; 
 they are formed either by electrical powers, or by the 
 agency of potassium, from the dilFerent earths whose 
 names they bear, with the change of the termination in 
 um ; and the numbers representing them are believed 
 to be 90 strontium, 40 calcium, 38 magnesium, 3l sili- 
 cum, 33 aluminum, 70 zirconum, 39 glueinum, 111 it- 
 trium. 
 
 Of the remaining simple bodies, twelve are metals, 
 most of which, like those just mentioned, can only be 
 procured Avith very great difficulty ; and the substances in 
 
40 
 
 general from which they are procured are very rare in 
 nature. They are Palladium, Rhodium^ Osmium, Iri- 
 dium, Columbium, Chromium, Molybdenum, Cerium, 
 Tellurium, Tungstenum, Titanium, Uranium. The 
 numbers representing these last bodies have not yet been 
 determined with sufficient accuracy to render a refer- 
 ence to them of any utility. 
 
 The undecompounded substances unite with each 
 other, and the most remarkable compounds are formed 
 by the combinations of oxygene and chlorine with in- 
 flammable bodies and metals ; and these combinations 
 usually take place with much energy, and are associated 
 with fire. 
 
 Combustion in fact, in common cases, is the process 
 of the solution of a body in oxygene, as happens when 
 sulphur or charcoal is burnt ; or the fixation of oxygene 
 by the combustible body in a solid form, which takes 
 place when most metals are burnt, or when phosphorus 
 inflames ; or the production of a fluid from both bodies, 
 as when hydrogene and oxygene unite to form water. 
 
 When considerable quantities of oxygene or of chlo- 
 rine unite to metals or inflammable bodies, they often 
 produce acids: thus sulphureous, phosphoric, and bo- 
 racic acids are formed by a union of considerable quan- 
 tities of oxygene w ith sulphur, phosphorus, and boron : 
 and muriatic acid gas is formed by the union of chlorine 
 and hydrogene. 
 
 When smaller quantities of oxygene or chlorine unite 
 with inflammable bodies or metals, they form substances 
 not acid, and more or less soluble in water ; and the 
 metallic oxides, the fixed alkalies, and the earths, all 
 bodies connected by analogies, are produced by the 
 union of metals with oxygene. 
 
 The composition of any compounds, the nature of 
 which is well known, may be easily learnt from the 
 numbers representing their elements ; all that is neces- 
 sary, is to know how many proportions enter into union. 
 Thus potassa, or the pure caustic vegetable alkali, con- 
 sists of one proportion of potassium and one of oxygene, 
 and its constitution is consequently 75 potassium, 15 
 oxygene. 
 
 Carbonic acid is composed of two proportions of oxy- 
 gene 30, and one of carbon 11.4. 
 
41 
 
 Again, lime consists of one proportion of caldum 
 and one of oxygene, and it is composed of 40 of cal- 
 cium and 15 of oxygene. And corbonate of lime, or 
 pure chalk, consists of one proportion of carbonic acid 
 41.4, and one of lime 55. 
 
 Water consists of two proportions of hydrogene 2, 
 and one of oxygene 15 ; and when water unites to other 
 bodies in definite proi)ortions, the quantity is 17, or 
 some multiple of 17, i. e. 34 or 51, or 68, ^c. 
 
 Soda, or the mineral alkali, contains two proportions 
 of oxygene to one of sodium. 
 
 tdLmmonia, or the volatile alkali, is composed of six 
 proportions of hydrogene and one of azote. 
 
 Amongst the earths. Silica, or the earth of flints, pro- 
 bably consists of two proportions of oxygene to one of 
 silicum ; and Magnesia, Strontia, Baryta or Barytes, 
 Alumina, Zircona, Glucina, and Ittria, of one propor- 
 tion of metal and one of oxygene. 
 
 The metallic oxides in general consist of the metals 
 united to from one to four proportions of oxygene ; and 
 there are, in some cases, many different oxides of the 
 same matal ; thus there are three oxides of lead ; the 
 yellow oxide, or massicot, contains tvvo proportions of 
 oxygene ; the red oxide, or minium, three ; and the puce 
 coloured oxide four proportions. Again there are two 
 oxides of copper, the hlacTc and the orange; the black 
 contains two proportions of oxygene, the orange one. 
 
 For pursuing such experiments on tlie composition 
 of bodies as are connected with agricultural chemistry, 
 a few only of the undecompounded substances are ne- 
 cessary ; and amongst the compounded bodies, the com- 
 mon acid^, the alkalies, and the earths, are the most es- 
 sential svibstances. The elements found in vegetables, 
 as has been stated in the introductory lecture, are.very 
 few. Oxygene, hydrogene, and carbon, constitute the 
 greatest part of their organized matter. Azote, phos- 
 phorus, sulphur, manganesum, iron, silicum, calcium, 
 aluminum, and magnesium likewise, in different ar- 
 rangements, enter into their composition, or are found in 
 the agents to which they are exposed ; and these twelve 
 undecompounded substances are the elements, the study 
 
42 
 
 of which is of tKe most importance to the agricultural 
 chemist. 
 
 Tiic doctrine of definite combinations, as will be 
 shewn in the following lectures, will assist us in gaining 
 just views respecting the composition of plants, and the 
 economy of the vegetable kingdom ; but the same ac- 
 curacy of weight and measure, the same statistical re- 
 sults which depend upon the uniformity of the laws that 
 govern dead matter, cannot be expected in operations 
 where the powers of life are cencerned, and where a 
 diversity of organs and of functions exists. The class- 
 es of definite inorganic bodies, even if we include all 
 the crystalline arrangements of the mineral kingdom, 
 are few, compared with the forms and substances be- 
 longing to animated nature. Life gives a peculiar char- 
 acter to all its productions ; the power of attraction and 
 repulsion, combination and decomposition, are subser- 
 vient to it ; a few elements, by the diversity of their 
 arrangement, are made to form the most diflferent sub- 
 stances ; and similar substances are produced from 
 compounds, whith, when superficially examined, ap- 
 pear entirely different. 
 
LECTUHE III. 
 
 On the Organization of Plants. Of the Roots, Trunk, 
 and Branches. Of their Structure. Of the Epider- 
 mis. Of the cortical and alburnous Parts of Leaves, 
 Flowers, and Seeds. Of the chemical Constitution 
 of the Organs of Plants, and the Substances found 
 in them. Of mucilaginous, saccharine, extractive, 
 resinous, and oily Substances, and other vegetable 
 Compounds, their Arrangements in the Organs of 
 Plants, their Composition, Changes, and Uses. 
 
 V ARIETY characterises the vegetable kingdom, yet 
 there is an analogy between the forms and the functions 
 of all the diJSferent classes of plants, and on this analo- 
 gy the scientific principles relating to their organization 
 depend. 
 
 Vegetables are living structures distinguished from 
 animals by exhibiting no signs of perception, or of vo- 
 luntary motion ; and their organs are either organs of 
 nourishment or of reproduction ; organs for the preser- 
 vation and increase of the individual, or for the multi- 
 plication of the species. 
 
 In the living vegetable system there are to be consi- 
 dered, the exterior form, and the interior, constitution. 
 
 Every plant examined as to external structure, dis- 
 plays at least four systems of organs, or some analo- 
 gous parts. First, the Root ; secondly, the Trunk and 
 Branches, or Stem ; thirdly, the Leaves ; and fourthly, 
 the Flowers or Seeds. 
 
 The 7'oot is that part of the vegetable which least 
 impresses the eye ; but it is absolutely necessary. It 
 attaches the plant to the surface, is its organ of nourish- 
 ment, and the apparatus by which it imbibes food from 
 the soil. The roots of plants, in their anatomical di- 
 vision, are very similar to the trunk and branches. The 
 root may indeed be said to be a continuation of the trunk 
 terminating in minute ramifications and filaments, and 
 
44 
 
 not iu leaves : and by burying the branches of certain 
 trees in tlic soil, and elevating the roots iu the atmos- 
 phere, there is, as it were, an inversion of the functions, 
 the roots produce buds and leaves, and the" brances 
 shoot out into radical fibres and tubes. This experiment 
 was made by Woodward on the willow, and has been 
 repeated by a number af physiologists. 
 
 When the branch or the root of a tree is cut trans- 
 vetsely, it usually exhibits three distinct bodies : the 
 bark, the wood, and the pith ; and these again are in- 
 dividually susceptible of a new division. 
 
 The bark when perfectly formed, is covered by a thin 
 cuticle or epidermis^ which may be easily separated. 
 'It is generally composed of a number of laminae or 
 scales, which in old trees are usually in a loose and de- 
 caying state. The epidermis is not vascular, and it 
 merely defends the interior parts from injury. In fo- 
 rest trees, and in the larger shrubs, the bodies of which 
 are firm, and of strong texture, it is a part of little im- 
 portance; but in the reeds, the grasses, canes, and the 
 plants having hollow stalks, it is of great use, and is 
 exceedingly strong, and in the microscope seems com- 
 posed of a kind of glassy net-work, which is princi- 
 pally siliceous earth. 
 
 This is the case in wheat, in the oat, in different spe- 
 cies of equisetum, and above all, in the rattan, the epi- 
 dermis of which contains a suflRcient quantity of flint 
 to give light when struck by steel ; or two pieces rub- 
 bed together produce sparks. This fact first occurred 
 to me in 1798, and it led to experiments, by which I 
 ascertained that siliceous earth existed generally in the 
 epidermis of the hollow plants. 
 
 The siliceous epidermis serves as a support, protects 
 the bark from the action of insects, and seems to per- 
 form a part in the economy of these feeble vegetable 
 tribes, similar to that performed in the animal kingdom, 
 by the shell of the crustaceous insects. 
 
 Immediately beneath the epidermis is the parenchy- 
 ma. It is a soft substance consisting of cells filled with 
 fluid, having almost always a greenish tint. The cells 
 in the parenchymatous part, when examined by the mi- 
 croscope, appear hexagonal. This form, indeed, is that 
 usually affected by the cellular membranes iji vegeta* 
 
45 
 
 tiles, and it seems to be the result of the general re-ac- 
 tion of the solid parts, similar to that which takes place 
 in the honey-comb. This arrangement, which has 
 usually been ascribed to the skill and artifice of the bee, 
 seems as Dr. Wollaston has observed, to be merely the 
 result of. the mechanical laws which influence the pres- 
 sure of cylinders composed of soft materials, the nests 
 of solitary bees being uniformly circular. 
 
 The innermost part of the bark is constituted by the 
 cortical layers, and their numbers vary with the age of 
 the tree. On cutting the bark of a tree of several years 
 standing, the productions of different periods may be 
 distinctly seen, though the layer of every particular year 
 can seldom be accurately defined. 
 
 The cortical layers are composed of fibrous parts 
 which appear interwoven, and which are transverse and 
 longitudinal. The transverse are membraneous and 
 porous, and the longitudinal are generally composed of 
 tubes. 
 
 The functions of the parenchymatous and cortical 
 parts of the bark are of great importance. The tubes 
 of the fibrious parts appear to be the organs that receive 
 the sap ; the cells seem destined for the elaboration of 
 its parts, and for the exposure of them to the action of 
 the atmosphere, and the new matter is annually produ- 
 ced in the spring, immediately on the inner surface of 
 the cortical layer of the last year. 
 
 It has been shewn by the experiments of Mr. Knight, 
 and those made by other physiologists, that the sap de- 
 scending tiirough the bark after being modified in the 
 leaves, is the principal cause of the growth of the tree ; 
 thus, if the bark is wounded, the principal formation of 
 new bark is on the upper edge of the wound ; and 
 when the wood has been removed, the formation of 
 new wood takes place immediately beneath the bark : 
 yet it would appear from the late observations of M. 
 Palisot de Beauvois, that the sap may be transferred to 
 the bark, so as to exert its nutritive functions, indepen- 
 dent of any general system of circulation. That gentle- 
 man separated different portions of bark from the rest 
 of the bark in several trees, and found that in most in- 
 stances the separated bark grew in the same manner as 
 the bark in its natural state. The experiment was tri- 
 
46 
 
 ed with most success on the lime-tree, the maple, and 
 the lilac ; the layers of bark were removed in August 
 1810, and in the spring of the next year, in the case of 
 the maple and the lilac, small annual shoots were pro- 
 duced in the parts where the bark was insulated.* 
 
 The wood of trees is composed of an external or li- 
 ving part, called alhurmim, or sap-wood, and of an in- 
 ternal or dead part, the heart-wood. The alburnum is 
 white, and full of moisture, and in young trees and an- 
 nual shoots it reaches even to the pith. The alburnum 
 is the great vascular system of the vegetable through 
 which the sap rises, and the vessels in it extend from 
 the leaves to the minutest filaments in the roots. 
 
 There is in the alburnum a membranous substance com- 
 posed of cells, which are constantly filled with the sap 
 of the plant, and there are in the vascular system seve- 
 ral different kind of tubes ; Mirbel has distinguished 
 four species, the simple tubes, the porous tubes, the tra- 
 cheae, and i\\Q false trachem.-\ 
 
 Tlie tubes, which he has called simple tubes, seem 
 to contain the resinous or oily fluids peculiar to differ- 
 ent plants. 
 
 The porous tubes likewise contain these fluids ; and 
 their use is probably that of conveying them into the sap 
 for the production of new arrangements. 
 
 The tracheae contain fluid matter, which is always 
 thin, watery, and pellucid, and these organs, as well as 
 the false trachese, probably carry off water from the 
 denser juices, which are thus enabled to consolidate for 
 the production of new wood. 
 
 In the arrangement of the fibres of the w^ood, there 
 are two distinct appearances. There are series of white 
 and shining laminae which shoot from the centre towards 
 the circumference, and these constitute what is called 
 the silver grain of the wood. 
 
 There are likewise numerous series of concentric lay- 
 ers which are usually called the spurious grain, and 
 their number denotes the age of the tree.J 
 
 * Fig. 3, represents the result of the experiment on the maple. 
 Journal de Physique, Scptemher 1811, page 210. 
 
 t Fig. 4, 5, 6, and 7, represent Mirbel's idea of the simple tubes, 
 the porous tubes, the tracliese, and the false tracheae. 
 
 I Fig. 8, represents the section of an elm branch, which exhibits 
 
47 
 
 The silver grain is elastic and contractile, and it has 
 been supposed by Mr. Knight, that the change of volnme 
 produced in it by change of temperature is one of the 
 principal causes of the ascent of the sap. The fibres of 
 it seem always to expand in the morning, and contract 
 at night; and the ascent of the juices, as was stated 
 in the last Lecture, depends principally on the agency 
 of heat. 
 
 The silver grain is most distinct in forest trees ; but 
 even annual shrubs have a system of fibres similar to it. 
 The analogy of nature is constant and uniform, and si- 
 milar effects are usually produced by similar organs. 
 
 The jpith occupies the centre of the wood ; its texture 
 is membranous ; it is composed of cells, which are cir- 
 cular towards the extremity, and hexagonal in the cen- 
 tre of the substance. In the first infancy of the vegeta- 
 ble, the pith occupies but a small space. It gradually 
 dilates, and, in annual shoots and young trees offers a 
 considerable diameter. In the more advanced age of 
 the tree, acted on by the heart- wood, pressed by the 
 new layers of the alburnum, it begans to diminish, and 
 in very old forest trees disappears altogether. 
 
 Many different opinions have prevailed with regard 
 to the use of the pith. Dr. Hales supposed, that it was 
 the great cause of the expansion and developement of 
 the other parts of the plant; that being the most interi- 
 or, it was likewise the most acted upon of all the or- 
 gans, and that from its re-action the phenomena of their 
 developement and growth resulted. 
 
 Linnaeus, whose lively imagination was continually 
 employed in endeavours to discover analogies between 
 the animal and vegetable systems, conceived " tliat the 
 pith performed for the plant the same functions as the 
 brain and nerves in animated beings." He considered it 
 as the organ of irritability and the seat of life. 
 
 The latest discoveries have proved that these two 
 opinions are equally erroneous. Mr. Knight has remo- 
 ved the pith in several young trees, and they continued 
 to live and to increase. 
 
 the tubular structure and the silver and spurious grain. Fig. 9, re- 
 presents the section of part of the branch of an oak. Fig. 10, that 
 of the branch of an ash. 
 
48 
 
 It is evidently then only an organ of secondary im- 
 portance. In early shoots, in vigorous growth, it is fill- 
 ed with moisture, and it is a reservoir, perhaps, of fluid 
 nourishment at the time it is most wanted. As the heart- 
 vrood forms, it is more and more separated from the li- 
 ving part, the alburnum ; its functions become exstinct, 
 it diminishes, dies, and at last disappears. 
 
 The tendrils, the spines, and other similar parts of 
 plants, are analogious in their organization to the branch- 
 es, and offer a similar corticle and alburnous organiza- 
 tion. It has been shewn, by the late observations of 
 Mr. Knight, that the directions of tendrils, and the spi- 
 ral form they assume, depend upon the unequal action 
 of light upon them, and a similar reason has been as- 
 signed by M. Decandolle to account for the turning of 
 the parts of plants towards the sun ; that ingenious phy- 
 siologist supposes that the fibres are shortened by the 
 chemical agency of the solar rays upon thejn, and that, 
 consequently, the parts will move towards the light. 
 
 The leaves, the great sources of the permanent beau- 
 ty of vegetation, though infinately diversified in their 
 forms, are in all cases similar in interior organization, 
 and perform the same functions. 
 
 The alburnum spreads itself from the foot-stalks into 
 the very extremity of the leaf; it retains a vascular sys- 
 tem and its living powers ; and its peculiar tubes, par- 
 ticularly the tracheae, may be distinctly seen in the 
 leaf.* 
 
 The green membranous substance may be considered 
 as an extension of the parenchyma, and the fine and thin 
 covering as the epidermis. Thus the organization of 
 the roots and branches may be traced into the leaves, 
 which present, however, a more perfect, refined, and 
 minute structure. 
 
 One great use of the leaves is, for the exposure of the 
 sap to the influence of the air, heat, and light. Their 
 surface is extensive, the tubes and cells very delicate, 
 and their texture porous and transparent. 
 
 In the leaves much of the water of the sap is evapo- 
 
 * Fig. 1 1) represents part of a leaf of a vine magnified and cut, so 
 as to exhibit the tracheae ; it is copied, as are also the preceding fig- 
 ures, from Grew's Anatomy of Plants, 
 
49 
 
 mteil ; it is combined witii new principles, and iitled foi* 
 its organizing functions, and probably passes, in its pre- 
 pared state, from the extreme tubes of the alburnum in- 
 to the ramifications of the cortical tubes, and then de- 
 scends through the bark. 
 
 On the upper surface of leaves, which is exposed to 
 the sun, the epidermis is thick but transparent, and is 
 composed of matter possessed of little organization, 
 which is either principally earthy, or consists of some 
 homogenous chemical substance. In the grasses it is 
 partly siliceous, in the laurel resinous, and in the ma- 
 ple and thorn, it is principally constituted by a substance 
 analogious to wax. 
 
 By these arrangements any evaporation, except from 
 the appropriated tubes, is prevented. 
 
 On the lower surface the epidermis is a thin transpa- 
 rent membrane full of cavities, and it is probably alto- 
 gether by this surface that moisture and the principles 
 of the atmosphere necessary to vegetation are absorb- 
 ed. 
 
 If a leaf be turned, so as to present its lower surface 
 to the sun, its fibres will twist so as to bring it as much 
 as possible into its original position ; and all leaves ele- 
 vate themselves on the foot-stalk during their exposure 
 to the solar light, and as it were move towards the sun. 
 
 This effect seems in a great measure dependent upon 
 the mechanical and chemical agency of light and heat. 
 Bonnet made artificial leaves, which, when a moist sponge 
 was held under the lower surface, and a heated iron 
 above the upper surface, turned exactly in the same man- 
 ner as the natural leaves. This however can be consider- 
 ed only as a very rude imitation of the natural process, 
 
 AVhat Linnaeus has called the sleep of the leaves, ap- 
 pears to depend wholly upon the defect of the action of 
 light and heat, and the excess of the operation of mois- 
 ture. 
 
 This singular but constant phenomenon, had never 
 been scientifically observed, till the attention of the bo- 
 tanist of Upsal was fortunately directed to it. He was 
 examining particularly a species of lotus, in which four 
 flow ers had appeared during the day, and he missed two 
 in the evening; by accurate inspection, he soon discover^ 
 
50 
 
 ed that these two were hidden by the leaves which had 
 closed round them. Such a circumstance could not he 
 lost upon so acute an observer. lie immediately took 
 a lantern, went into his garden, and witnessed a series of 
 curious facts before uuknown. All the simple leaves of 
 the plants he examined, had an arrangement totally dif- 
 ferent from their arrangement in the day : and the greater 
 number of them were seen closed or folded together. 
 
 The sleep of leaves is, in some cases, capable of be- 
 ing produced artificially. Decandolle made this experi- 
 ment on the sensitive plant. By confining it in a dark 
 place in the daytime, the leaves soon closed ; but on il- 
 luminating the chamber with many lamps, they again ex- 
 panded. So sensible were they to the eflPects of light and 
 radiant heat. 
 
 In the greater number of plants the leaves annually 
 decay, and are repruduced; their decay takes place ei- 
 ther at the conclusion of the summer, as in very hot cli- 
 mates, when they are no longer supplied with sap, in 
 consequence of the dryness of the soil, and the evapo- 
 rating powers of heat; or in the autumn, as in the north- 
 ern climates at the commencement of the frosts. The 
 leaves preserve their functions in common cases no long- 
 er than there is a circulation of fluids through them. In 
 the decay of the leaf, the colour assumed seems to de- 
 pend upon the nature of the chemical change, and as 
 acids are generally developed, it is usually either red- 
 dish brown or yellow ; yet there are great varieties. 
 Thus in the oak, it is a bright brown ; in the beech, 
 orange ; in the elm, yellow ; in the vine, red ; in the sy- 
 camore, dark brown ; in the cornel tree, purple ; and in 
 the woodbine, blue. 
 
 The cause of the preservation of the leaves of ever- 
 greens through the winter is not accurately known. From 
 the experiments of Hales, it appears that the force of 
 the sap is much less in plants of this species, and pro- 
 bably there is a certain degree of circulation throughout 
 the winter; their juices are less watery than those of 
 other plants, and probably less liable to be congealed 
 by cold, and they arc defended by stronger coatings 
 from the action of the elements. 
 
 The production of the other parts of the plant takes 
 
5i 
 
 place at the time the leaves are most vigorously perform- 
 ing their functions. If the leaves are stripped off from 
 a tree in spring, it uniformly dies, and when many of the 
 leaves of forest trees are injured by blasts, the trees al- 
 ways become stag-headed and unhealthy. 
 
 The leaves are necessary for the existence of the in- 
 dividual tree, the Jlowers for the continuance of the spe- 
 cies. Of all the parts of plants they are the most refi- 
 ned, the most beautiful in their structure, and appear as 
 the master- work of nature in the ve2;etable kiu2;dom. 
 The elegance of their tints, the variety of their forms, 
 the delicacy of their organization, and the adaptation of 
 their parts are all calculated to awaken our curiosity, and 
 excite our admiration. 
 
 In the tlower there are to be observed, 1st, the calyx, 
 or the green membranous part forming the support for 
 the coloured floral leaves. This is vascular, and agrees 
 with the common leaf in its texture and organization ; 
 it defends, supports, and nourishes the more perfect 
 parts. 2d. The corolla, which consists either of a sin- 
 gle piece, when it is called monopetalous, or of many 
 pieces, when it is called polypetalous. It is usually 
 very vivid in its colours, is filled with an almost infinite 
 variety of small tubes of the porous kind ; it encloses 
 and defends the essential parts in the interior, and sup- 
 plies the juices of the sap to them. These parts are, 
 3d, the stamens and the pistils. 
 
 The essential part of the stamens are the summits or 
 anthers, which are usually circular and of a highly vas- 
 cular texture, and covered with a fine dust called the 
 pollen. 
 
 The pistil is cylindrical, and surmounted by the style; 
 the top of which is generally round and protuberant.* 
 
 In the pistil, when it is examined by the microscope, 
 congeries of spherical forms may usually be perceived, 
 which seem to be the basis of the future seeds. 
 
 It is upon the arrangement of the stamens and the pis- 
 tils that the Linnasan classification is founded. The 
 numbers of the stamens and pistils in the same flower, 
 their arrangements, or their division in different flowers, 
 
 * Fig. 1 2, represents the common lily, a, the corolla, bbbib, the 
 anthei-s, r, the pistil. 
 
52 
 
 are the circumstances which guided the Swedish philo- 
 sopher, and enabled him to form a system admirably 
 adapted to assist the memory, and render botany of easy 
 acquisition : and which, though it does not always as- 
 sociate together the plants most analogous to each in 
 their general characters, is yet so ingeniously contrived 
 as to denote all the analogies of their most essential parts. 
 
 The pistil is the organ which contains the rudiments 
 of the seed ; but the seed is never formed as a repro- 
 ductive germ, without the influence of the pollen, or dust 
 on the anthers. 
 
 This mysterious impression is necessary to the con- 
 tinued succession of the different vegetable tribes. It 
 is a feature which extends the resemblances of the dif- 
 ferent orders of beings, and establishes, on a great scale, 
 the beautiful analogy of nature. 
 
 The ancients had observed, that different date trees 
 bore different flowers, and that those trees producing 
 flowers which contained pistils bore no fruit, unless in 
 the immediate vicinity of such trees as produced flow- 
 ers containing stamens. This long established fact 
 strongly impressed the mind of Malpighi, who ascer- 
 tained several analogous facts with regard to other ve- 
 getables. Grew, however, was the first person who at- 
 tempted to generalize upon them, and much just rea- 
 soning on the subject may be found in his works. Lin- 
 naeus gave a scientific and distinct form to that which 
 Grew had only generally observed, and has the glory of 
 establishing what has been called the sexual system, upon 
 the basis ofminute observations and accurate experiments. 
 
 The seed, the last production of vigorous vegetation, 
 is wonderfully diversified in form. Being of the high- 
 est importance to the resources of nature, it is defend- 
 ed above all other parts of the plant ; by soft pulpy sub- 
 stances, as in the esculent fruits, by thick membranes, as 
 in the leguminous vegetables, and by hard shells, or a 
 thick epidermis, as in the palms and grasses. 
 
 In every seed there is to be distinguished, 1, the or- 
 gan of nourishment ; 2, the nascent plant, or thep/zt?He; 
 8, the nascent root, or the radicle. 
 
 In the common garden bean, the organ of nourish- 
 ment is divided into two lobes called cotyledons ; tire 
 
53 
 
 plume is the small white point between the ufper pan 
 of the lobes ; and the radicle is the small curved coue 
 at their base.* 
 
 In wheat, and in many of the grasses, the orgaji of 
 nourishment is a single part, and these plants are cEill- 
 ed monocotyledonous. In other cases it consists of more 
 than two parts, when the plants are called polycutyUdo- 
 nous. In the greater number of instances it is, how- 
 ever, simply divided into two, and is dicotyledonous^ 
 
 The matter of the seed, when examined in its com- 
 mon state, appears dead and inert ; it exhibits neither 
 the forms nor the functions of life. But let it be acted 
 upon by moisture, heat, and air, and its organized pow- 
 ers are soon distintly developed. The cotyledons ex- 
 pand, the membranes burst, the radicle acquires new 
 matter, descends into the soil, and the plume rises to- 
 wards the free air. By degrees, the organs of nourish- 
 ment of dicotyledonous plants become vascular, and are 
 converted into seed leaves, and the perfect plant ap- 
 pears above the soil. Nature has provided the eleoients 
 of germinations on every part of the surface ; water and 
 pure air and heat are universally active, and the means 
 for the preservation and multiplication of life, are at 
 once simple and grand. 
 
 To enter into more minute details on the vegetable 
 physiology would be incompatable with the objects of 
 these Lectures. 1 have attempted only to give such ge- 
 neral ideas on the subject, as may enable the philoso- 
 phical agriculturist to understand the functions of plants ; 
 those who wish to study the anatomy of vegetables, as 
 a distinct science, will find abundant materials in the 
 works of the authors I have quoted, page, 13, and like- 
 wise in the writings of Linuceus, Uesfontaines, Decan- 
 dolle, de Saussure, Bonnet, and Smith. 
 
 The history of the peculiarities of structure in the 
 diff'erent vegetable classes, rather belongs to botanical 
 than agricultural knowledge. As I mentioned in the 
 commencement of this Lecture, their organs are pos- 
 sessed of the most distinct analogies, and are governed 
 
 * Fig. 1 3, represents the garden bean, aa, the cotyledons, b, the 
 plume, c, the radicle. 
 
51 
 
 by the same laws. In the grasses and palms, the cor- 
 tical layers are larger in proportion than the other parts ; 
 bnt their uses seem to be the same as in forest trees. 
 
 In bulbous roots, the alburnous substance forms the 
 largest part of the vegetable ; but in all cases it seems 
 to contain the sap, or solid materials deposited from the 
 sap. 
 
 The slender and comparatively dry leaves of the pine 
 and the cedar perform the same functions as the large 
 and juicy leaves of the fig-tree or the walnut. , 
 
 Even in the cryptogamia, where no flowers are dis- 
 tinct, still there is every reason to believe that the pro- 
 duction of the seed is effected in the same w ay as in the 
 more perfect plants. The mosses and lichens, which 
 belong to this family, have no distinct leaves or roots, 
 but they are furnished with filaments which perform the 
 same functions ; and even in the fungus and the mushroom 
 there is a system for the absorption and aeration of the 
 sap. 
 
 It was stated in the last Lecture, that all the different 
 parts of the plants are capable of being decomposed into 
 a few elements. Their uses as food, or for the purpo- 
 ses of the arts, depend upon compound arrangements of 
 those elements which are capable of being produced ei- 
 ther from their organized parts, or from the juices they 
 contain ; and the examination of the nature of these sub- 
 stances, is an essential part of Agricultural Chemis- 
 
 try. 
 
 Oils are expressed from the fruits of many plants; 
 resinous fluids exude from the wood ; saccharine mat- 
 ters are afforded by the sap ; arid dyeing materials are 
 furnished by leaves, or the petals of flowers : but par- 
 ticular processes are necessary to separate the different 
 compound vegetable substances from each other, such as 
 maceration, infusion or digestion in water, or in spirits 
 of wine: butthe aj)plicationandthe nature of these pro- 
 cesses will be better understood when the chemical na- 
 ture of the substances is known; the consideration of 
 them will therefore be reserved for another place in this 
 Lecture. 
 
 The cojnpound substances found in vegetables are, 1, 
 gum, or anucilage, and its different modifications : 2, 
 
r. &i 
 
 
 Fi'<7.3. 
 
Fig" io. 
 
55 
 
 btarch ; 3, sugar ; 4, albumen ; 5, gluten ; 0, gum clas^- 
 tic; 7, extract; 8, tannin ; 9, indigo; 10, narcotic princi- 
 ple; 11, bitter principle ; 12, wax; 13, resins ; 14, cam- 
 phor; 15, fixed oils ; 16, volatile oils ; 17, woody fil)re; 18, 
 acids; 19, alkalies; earths, metallic oxides, and saline 
 compounds. 
 
 I shall describe generally the properties and compo- 
 sition of these bodies, and the manner in which they are 
 procured. 
 
 1. Gum is a substance which exudes from certain 
 trees ; it appears in the form of a thick fluid, but soon 
 hardens in the air, and becomes solid ; wlien it is white, 
 or yellowish white, more or less transparent, and some- 
 what brittle ; its specific gravity varies from 1300 to 
 1490. 
 
 There is a great vai'iety of gums, ])ut tlie best known 
 are gum arabic, gum Senegal, gum tragacanth, and the 
 gum of the plum or cherry tree. Grum is soluble in wa- 
 ter, but not soluble in spirits of w^ine. If a solution of 
 gum be made in water, and spirits of wine or alcohol 
 be added to it, the gum separates in the form of w^hitc 
 flakes. Gum can be made to inflame only with'difficul- 
 ty; much moisture is given oft* in the process, which 
 takes place with a dark smoke and feeble blue flame, 
 and a coal remains. 
 
 The characteristic properties of gum are its easy so- 
 lubility in water, and its insolubility in alcohol. Dif- 
 ferent chemical substances have been proposed for as- 
 certaining the presence of gum, but tliere is reason to 
 believe that few of them aft'ord accurate results ; and 
 most of them (particularly the metallic salts,) which pro- 
 duce changes in solutions of gum, may be conceived to 
 act rather upon some saline compounds existing in the 
 gum, than upon the pure vegetable principle. Ur. 
 Thomson has proposed an aqueous solution of silica in 
 potassa, as a test of the presence of gum in solutions — 
 he states that the gum and silica are precipitated toge- 
 ther — ^this test, however, cannot be applied with cor- 
 rect results in cases when acids are present. 
 
 Mucilage must be considered as a variety of gum; it 
 agrees with it in its most important properties, but seems 
 to liave less attraction for water. — According to Uermb- 
 stadt, when £;um and mucilage are dissohrd <o«rether w 
 
56 
 
 water, the mucilage may be separated by means of sul- 
 phuric acid — mucilage may be procured fro^n linseed, 
 from the bulbs of the hyacinth, from the leaves of the 
 marshmallovts ; from several cf the lichens, and from 
 many other vegetable substances. 
 
 From the analysis of M. M. Gay Lussac and The- 
 
 nard, it appears that gum arable contains in 100 parts: 
 
 of carbon - - 42,23 
 
 — oxygene - - 50,84 
 
 — hydrogene - - 6,93 
 
 with earthy matter a small quantity of saline and. 
 
 or of carbon - - 42,23 
 oxygene and hydrogene ^ 
 in the proportions ne- C 57,77 
 cessary to form water 3 
 
 This estimation agrees very nearly with the deiinite 
 proportions of 11 of carbon, 10 of oxygene, and 20 of 
 hydrogene. 
 
 All the varieties of gum and mucilage are nutritious 
 as food. They either partially or wholly lose their so- 
 lubility in water by being exposed to a heat of 500° or 
 600^ Fahrenheit, but their nutritive powers are not de- 
 stroyed unless they are decomposed. Gum and muci- 
 lage are employed in some of the arts, particularly in 
 calico-printing : till lately, in this country, the calico- 
 printers used gum arable; but many of them, at the sug- 
 gestion of Lord Dundonald, now employ the mucilage 
 from lichens. 
 
 2. Starch is procured from different vegetables, but 
 particularly from Miieat or from potatoes. To make 
 starch from wheat, the grain is steeped in cold water till 
 it becomes soft, and yields a milky juice by pressure ; 
 it is then put into sacks of linen, and pressed in a vat 
 filled with water : as long as any milky juice exudes the 
 pressure is continued ; the fluid gradually becomes clear, 
 and a white powder subsides Avhich is starch. 
 
 Starch is soluble in boiling water, but not in cold wa- 
 ter, nor in spirits of wine. According to Dr. Thomson, 
 it is a cliaracteristic property of starch to be solul)le in 
 a warm infusion of nutgalls, and to form a precipitate 
 when the infusi(ui cools. 
 
 Starch is more readily combustible than gum; when 
 
lUo Jl. 
 
57 
 
 thrown upon red hot iron, it burns with a kind of ex- 
 plosion, and scarcely any residuum remains. Accord- 
 ing to Mr. Gay Lussac and Thenard, 100 parts of starch 
 are composed of 
 
 Carbon, with a small quau- ^ 
 
 tity of saline and earthy V 43,55 
 
 matter - * ~ 3 
 
 Oxygene - - - 49,68 
 Hydrogene - - - 6,7T 
 or, 
 
 Carbon - - - - 
 
 Oxygene and hydrogene in 
 
 the proportions necessary 
 
 to form water 
 
 Supposing this estimation correct, starch may be con- 
 ceived to be constituted by 15 proportions of carbon, 
 13 of oxygene, and 26 of Iiydrogene. 
 
 Starch forms a principal part of a number of escu- 
 lent vegetable substances. Sowans, cassava, salop, sa- 
 go, all of them owe their nutritive powers principally 
 to the starch they contain. 
 
 Starch has been found in the following plants : 
 
 Burdock {Arctium Lappa^) Deadly Nightshade {Jlt- 
 ropa Belladonna^) Bistort {Polygonum Bistorta,) WhiiQ 
 Bryony {Brijonia alba,) Meadow Saffron {Colcliicum 
 autumiiale,) Dropwort {Spircea Filipendulay) Buttercup 
 (Ranunculus bulbosiis,) Figvvort {Scrophularia nodosa^) 
 Dwarf Elder {Samhiicus Ebulus,) Common Elder 
 (Sambuciis nigra.) Fool-stones [Orchis Morio,) Alex- 
 anders {Imperatoria Ostriithium,) Henbane [Hijoscya- 
 mus niger^ Broad-leaved Dock {Rumex obtusifolius,) 
 Sharp-pointed Dock {Rumex acutiis.) Water Dock. 
 {Rumex aquaticus,) Wake Robin {Arum maculatum^) 
 Salep {Orchis mascula,) Flower de luce or Water flag 
 {Iris Pseudacorus) Stinkirig Gladwyn {Iris fmiidissi- 
 ma,) Earthnut {Bunium Bulbocastaniim.) 
 
 ii. Sugar in its purest state is prepared from the ex- 
 pressed juice of the Saccharum officinarmn, or sugar 
 cane ; the acid in this juice is neutralized by lime, and 
 the sugar is crystallized by the evaporation of thcaque- 
 
 H 
 
58 
 
 ous parts of the juice, and slow-cooling : it is rendered 
 wliite by the gradual filtration of water through'it. In 
 the common process of manufacture, the whitening or 
 refining of sugar is only effected in a great length of 
 time ; the water being gradually suffered to percolate 
 through a stratum of clay above the sugar. As the co- 
 louring matter of sugar is soluble in a saturated solu- 
 tion of sugar, or syrup, it appears that refining may be 
 much more rapidly and ceconomically performed by the 
 action of syrup on coloured sugar.* The sensible pro- 
 perties of sugar are well known. Its specific gravity, 
 according to Fahrenheit, is about 1.6. It is soluble in 
 its own weight of water at 50° ; it is likewise soluble 
 in alcohol, but in smaller proportions. 
 
 Lavoisier concluded from his experiments, that sugar 
 consists in 100 parts of 
 
 28 carbon, 
 
 8 hydrogene, 
 64 oxygene. 
 Dr. Thompson considers 100 parts of sugar as com- 
 posed of 
 
 27,5 carbon, 
 
 7,8 hydrogene, 
 64,7 oxygene. 
 According to the recent experiments of Gay Lussac 
 and Thenard, sugar consists of 42,47 of carbon, and 
 57,53 of water or its elements. 
 Lavoisier's and Dr. Thomson's analysis agree very 
 nearly with the proportions of 
 
 3 of carbon, 
 
 4 of oxygene, 
 and 8 of hydrogene. 
 
 * A French gentleman lately in this country, stated to the West 
 India planters, that he was in possession of a very expeditous and eco- 
 nomical method of purifying and refining sugar, which he was willing 
 to communicate to them for a very great pecuniary compensation. 
 Ilis terms were too high to be acceded to. Conversing on the sub- 
 ject wiih -Sir Joseph Banks, I mentioned to him, that I thought it 
 probable that raw sugar might be easily purified by passing syrup 
 through it, which would dissolve the colouring matter. The same 
 idea seems to have occurred about the same time, or before, to Ed- 
 ward Howard, Esq. who has since proved its efficacy experimentally, 
 and has published an account of his process. 
 
59 
 
 Gay Lussac's and Thenard's estimation gives the 
 same elements as in gum ; H of carbon, 10 of oxygene, 
 20 of hydrogene. 
 
 It appears from the experiments of Proust, Achard, 
 Goettling, and Parmentier, that there are many differ- 
 ent species of sugar ready formed in the vegetable king- 
 dom. The sugar which most nearly resembles that of 
 the cane is extracted from the sap of the American ma- 
 ple, Acer Saccharinum. This sugar is used by the 
 North American farmers, who procure it by a kind of 
 domestic manufacture. The trunk of the tree is bored 
 early in spring, to the depth of about two inches : a 
 wooden spout is introduced into the hole ; the juice flows 
 for about five or six weeks. A common sized tree, that 
 is, a tree from two to three feet in diameter, will yield 
 about 200 pints of sap, and every 40 pints of sap afford 
 about a pound of sugar. The sap is neutralized by 
 lime, and deposits crystals of sugar by evaporation. 
 
 The sugar of grapes has been lately employed in 
 France as a substitute for colonial sugar. It is procur- 
 ed from the juice of ripe grapes by evaporation, and the 
 action of potashes ; it is less sweet than common sugar, 
 and its taste is peculiar : it produces a sensation of cold 
 while dissolving in the mouth ; and it is probable con- 
 tains a larger proportion of water or its elements. 
 
 The roots of the beet {Beta vulgaris and cicla,) af- 
 ford a peculiar sugar, by boiling, and evaporation of the 
 extract : it agrees in its general properties with the su- 
 gar of grapes, but has a slightly bitter taste. 
 
 Manna, a substance which exudes from various trees, 
 particularly from the Fraxinus Ornus, a species of ash, 
 which grows abundantly in Sicily and Calabria, may 
 be regarded as a variety of sugar, very analogous to the 
 sugar of grapes. A substance analogous to manna has 
 been extracted by Fourcroy and Vauquelin, from the 
 juice of the common onion {Allium Cepa,) 
 
 Besides the crystallized and solid sugars, there ap- 
 pears to be a sugar which cannot be separated from wa- 
 ter, and which exists only in a fluid form ; it constitutes 
 a principal part of molasses or treacle ; and it is found 
 in a variety of fruits : and it is more soluble in alcohol 
 than solid sugar. 
 
(\0 
 
 TIm' siiiiplosi mode oi" deiecline; sugar is that rcconi 
 luemlcd l).y JVlavi^raaf. The vegetable is to be boiled 
 ill a small quantity of alcohol; solid sugar, if any exist, 
 "will separate during the cooling of the solution. 
 
 Sugar lias been extracted from the following vegeta- 
 ble supstauces : 
 
 The sap of the Birch (Betula alba,) of the Sycamore 
 {Acer FsimdopJatanus^) of the Bamboo [Arundo Bam- 
 boo.) of the Maize {yjea mays,) of the Cow Parsnip 
 [UenuieuiiL SphmdijUum.,) of the Cocoa-nut tree [Co- 
 cof) liucifcrtt^) oi' the Walnut tree [Juglans alba,) of the 
 American Al(>e [A^ave mci'icana,) of the Dulse [Fuciis 
 patmatus,) of the Common Parsnip {Pastinicd sativa,) 
 of St. John's J5read {Ceratonia Siliqua,) the fruit of 
 the (\)mm()n Arbutus {Arbutoft Unedo,) and other sweet 
 lasted fruits ; the roots of the turniji (Brassica Rapa,) 
 of the ('arrot {.Daucus Carota,) of Parsley [Apium pet- 
 rnadinnn/,) the flower of tiu' Euxine Khododendron 
 [Rhododendron poiiticiniu) and from the nectarium of 
 most, other flowers. 
 
 The nutritive properties of sugar are well known. 
 Since the British market has been over-stocked witli 
 this article from the West India islands, proposals have 
 been made for applying it as the food of cattle ; experi- 
 ments have been made, which prove that they may be 
 fattened by it; l)ut ditficulties connected with tiie duties 
 laid on sugar, have hitiierto prevented the plan from 
 beind tried to any extent. 
 
 4. Albumen is a substance which has only lately been 
 discovered in the vegetable kingdom, it abounds in 
 the juice of the papavv-tree [Caryca Papaya:) when 
 this juice is boiled, tlie albumen falls down in a coagu- 
 lated state. It is likewise found in mushrooms, and in 
 ditlVvent species of funguses. 
 
 AUiumen in its pure form, is a thick, glairy, tasteless 
 fluid ; precisely the same as the white of tiie egg ; it is 
 -soluble in cold water ; its solution, vvlien not too diluted. 
 is coagulated by boiling, and the albumen separates in 
 the form of thin* flakes. Albumen is likewise coagula- 
 ted by acids and by alcohol : a solution of alhumen 
 gives a precipitate when mixed with a cold solution of 
 nut-galls. Albumen, when burnt, produces a smell of 
 
()1 
 
 volatile alkali, and aflbrtls carbonic acid and water; it 
 is therefore evidently principally composed of carbon, 
 hydrogene, oxygenc, and azote. 
 
 According to the experiments of Gay Lussac and 
 Thenard, 100 parts of albumen from the white of the 
 egg are composed of 
 
 Carbon - - - - 52,883 
 
 Oxygene - - - 23,872 
 
 Hydrogene - - 7,540 
 
 Azote - - - 15,705 
 
 This estimation would authorise the supposition, that 
 albumen is composed of 2 proportions of azote, 5 oxy- 
 gene, 9 carbon, 22 hydrogene. 
 
 The principal part of the almond, and of the kernels 
 of many other nuts, appears from the experiments of 
 Proust, to be a substance analogous to coagulated al- 
 bumen. 
 
 The juice of the fruit of the ochra {Hibiscus esculen- 
 tus,) according to Dr. Clarke, contains a li((uid albu- 
 men in such quantities, that it is employed in Domini- 
 ca as a substitute for the white of eggs in clarifying the 
 juice of the sugar-cane. 
 
 Albumen may be distinguished from other substances 
 by its property of coagulating by the action of heat or 
 acids, when dissolved in water. According to Dr. Bos- 
 tock, when the solution contains only one grain of albu- 
 men to 1000 grains of water, it becomes cloudy by ])c- 
 ing heated. 
 
 Albumen is a substance common to the animal as well 
 as to the vegetable kingdom, and much more abundant 
 in the former. 
 
 5. Gluten may be obtained from wheaten flour by the 
 following process : the ilour is to be made into a paste, 
 which is to be cautiously washed, by kneading it under 
 a small stream of water, till the water has carried oft' 
 from it all the starch ; what remains is gluten. It is a 
 tenacious, ductile, elastic substance. It has no taste. 
 By exposure to air it becomes of a brown colour. It is 
 very slightly soluble in water; I)nt not soluble in alco- 
 hol. When a solution of it in water is heated, the glu- 
 ten separates in tiie form of yellow flakes ; in tiiis res- 
 pect it agrees with albumen, but dift'ers from it in being 
 infinitely less soluble in water, '.riie solution of 'Aim- 
 
62 
 
 men does not coagulate when it contains much less 
 than 1000 parts of albumen ; but it appears that gluten 
 requires more than 1000 parts of cold water for its so- 
 lution. 
 
 Gluten, when burnt, affords similar products to albu- 
 men, and probably differs very little from it in composi- 
 tion. Gluten is found in a great number of plants ; Proust 
 discovered it in acorns, chesnuts, horse-chesnuts, apples, 
 and quinces ; barley, rye, peas, and beans ; likewise in 
 the leaves of rue, cabbage, cresses, hemlock, borage, saf- 
 fron, in the berries of the elder, and in the grape. Glu- 
 ten appears to be one of the most nutritive of the vege- 
 table substances ; and wheat seems to owe its superiori- 
 ty to other grain, from the circumstance of its contain- 
 ing it in larger quantities. 
 
 6. Gmn elastic, or Caoutchouc^ is procured from the 
 juice of a tree which grows in the Brazils, called Hse- 
 vea. When the tree is punctured, a milky juice exudes 
 from it, which gradually deposits a solid substance, and 
 this is gum elasic. 
 
 Gum elastic is pliable and soft like leather, and be- 
 comes softer when heated. In its pure state it is white ; 
 its specific gravity is 9335. It is combustible, and burns 
 with a white flame, throwing off a dense smoke, with a 
 very disagreeable smell. It is insoluble in water, and 
 in alcohol ; it is soluble in ether, volatile oils, and in 
 petroleum, and may be procured from ether in an unal- 
 tered state by evaporating its solution in that liquid. 
 Gum elastic seems to exist in a great variety of plants : 
 amongst them are, Jatropha elastica, Ficus indicaj Ar- 
 tocarpus integrifolia, and Urceola elastica. 
 
 Bird-lime, a substance which may be procured from 
 the holly, is very analogious to gum elastic in its pro- 
 perties. Species of gum elastic may be obtained from 
 the misletoe, from gum-mastic, opium, and from the ber- 
 ries of the Smilax caduca, in which last plant it has 
 been lately discovered by Dr. Barton. 
 
 Gum elastic when distilled, affords volatile alkali, 
 water hydrogene, and carbon in different combinations. 
 It therefore consists principally of azote, hydrogene, 
 oxygene, and carbon ; but the proportions in which they 
 arc combined have not vet been ascertained. Gum elas- 
 
63 
 
 tic is an indigestible substance, not fitted for tlie food of 
 animals ; its uses in the arts are well known. 
 
 7. Extract, or the extractive principle, exists in al- 
 most all plants. It may be procured in a state of tole- 
 rable purity from saftron, by merely infusing it in water, 
 and evaporating the solution. It may likewise be ob- 
 tained from catechu, or Terra japonica, a substance 
 brought from India. This substance consists principal- 
 ly of astringent matter, and extract ; by the action of wa- 
 ter upon it, the astringent matter is first dissolved, and 
 may be separated from the extract. Extract is always 
 more or less coloured ; it is soluble in alcohol and water, 
 but not soluble in ether. It unites with alumina when 
 that earth is boiled in a solution of extract ; and it is 
 precipitated by the salts of alumina, and by many me- 
 tallic solutions, particularly the solution of muriate of 
 tin. 
 
 From the products of its distillation, it seems to be 
 composed principally of hydrogene, oxygene, carbon, 
 and a little azote. 
 
 There appears to be almost as many varieties of ex- 
 tract as there are species of plants. The diiFerence of 
 their properties probably, in many cases, depends upon 
 their being combined with small quantities of other ve- 
 getable principles, or to their containing different saline, 
 alkaline, acid, or earthy ingredients. Many dyejing sub- 
 stances seem to be of the nature of extractive principle, 
 such as the red colouring matter of madder, and the yel- 
 low dye, procured from weld. 
 
 Extract has a strong attraction for the fibres of cotton 
 or linen, and combines with these substances when they 
 are boiled in a solution of it. The combination is made 
 stronger by the intervention of mordants, which are 
 earthy or metallic combinations that unite to the cloth, 
 and enable the colouring matter to adhere more strongly 
 to its fibres. 
 
 Extract in its pure form cannot be used as an article 
 of food, but it is probably nutritive when united to starch, 
 mucilage or sugar. 
 
 8. Tannin, or the tanning principle, may be procured 
 by the action of a small quantity of cold water on bruised 
 grape-seeds, or pounded gall-nuts ; and by the evapora 
 
64 
 
 tion of the solution to dryness. It appears as a yellow 
 substance, possessed of a highly astringent taste. It is 
 diificiilt of combustion. It is very soluble both in wa- 
 ter and alcohol, but insoluble in ether. When a solu- 
 tion of glue, or isinglass (gelatine,) is mixed with an 
 aqueous solution of tannin, the two substances, i. e. the 
 animal and vegetable matters fall down in combination, 
 and form an insoluble precipitate. 
 
 When tannin is distilled in close vessels, the princi- 
 j)al products are charcoal, carbonic acid, and inflamma- 
 ble gases, with a minute quantity of volatile alkali. 
 Hence its elements seem the same as those of extract, 
 but probably in different proportions. The characteris- 
 tic property of tannin is its action upon solutions of isin- 
 glass or jelly; this particularly distinguishes it from ex- 
 tract, with which it agrees in most other chemical qua- 
 lities. 
 
 There are many varieties of tannin, which probably 
 owe the difference of their properties to combinations 
 with other principles, especially extract, from which it 
 is not easy to free tannin. The purest species of tannin 
 is that obtained from the seeds of the grape ; this forms 
 a white precipitate, with solution of isinglass. The tan- 
 nin from gall-nuts resembles it in its properties. That 
 from sumach affords a yellow precipitate ; that from ki- 
 no a rose coloured ; that from catechu a fawn coloured 
 one. The colouring matter of Brazil wood, which M. 
 Chevreul considers as a peculiar principle, and which he 
 has called Hematine, differs from other species of tan- 
 nin, in affording a precipitate with gelatine, which is so- 
 luble in abundance of hot water. Its taste is much 
 sweeter than that of the other varieties of tannin, and it 
 may, perhaps, be regarded as a substance intermediate 
 between tannin and extract. 
 
 Tannin is not a nutritive substance, but is of great im- 
 portance in its application to the art of tanning. Skin 
 consists almost entirely of jelly qy gelatine, in an organi- 
 zed state, and is soluble by the long continued action of 
 hoiling water. When skin is exposed to solutions con- 
 taining tannin, it slowly combines with that principle ; 
 its fibrous texture and coherence are preserved : it is 
 rendered perfectly insoluble in water, and is no longer 
 
p. 64 
 
 Fiq. 12. 
 
65 
 
 liable to putrefaction : in short, it becomes a substance 
 in chemical composition precisely analogous to that 
 furnished by tlie solution of jelly and the solution of 
 tannin. 
 
 In general, in this country, the bark of the oak is used 
 for affording tannin in tlie manufacture of leather ; but 
 the barks of some other trees, particularly the Spanish 
 chesnut, have lately come into use. The following ta- 
 ble will give a general idea of the relative value of dif- 
 ferent species of barks. It is founded on the result of 
 experiments made by myself. 
 
 Table of *N*iimhers exhibiting the quantify of Tannin 
 afforded by 480lbs. of different Barlcs, which express 
 nearly their relative Values. 
 
 Average of entire bark of middle-sized Oak, cut in 
 
 spring 
 
 of Spanish Chesnut 
 
 — — of Leicester Willow, large 
 
 size 
 
 of Elm 
 
 '. of Common Willow, large 
 
 of Ash 
 
 of Beech - - - 
 
 of Horse Chesnut 
 
 of Sycamore 
 
 of Lonibardy Poplar - 
 
 of Birch - - 
 
 of Hazel - - - 
 
 of Black Thorn 
 
 of Coppice Oak 
 
 ' • of Oak cut in autumn 
 
 of Larcli cut in autumn 
 
 White interior cortical layers of Oak Bark 
 
 29 
 21 
 
 33 
 13 
 11 
 16 
 10 
 
 9 
 11 
 15 
 
 8 
 14 
 16 
 32 
 21 
 
 8 
 72 
 
 The quantity of the tanning principle in barks dif- 
 fers in different seasons ; when the spring has been very 
 cold the quantity is smallest. On an average, four or 
 five pounds of good oak bark arc required to form one 
 pound of leather. The inner cortical layers in all barks 
 contain tlie largest quantity of tannin. Barks contain 
 
 r 
 
66 
 
 the greatest proportion of taimiu at the time the buds 
 begin to open — the smallest quantity in winter. 
 
 The extractive or colouring matters found in barks, 
 or in substances used in tanning, influence the quality 
 of leather. Thus skin tanned with gall-nuts is much 
 paler than skin tanned with oak bark, which contains 
 a brown extractive matter. Leather made from catechu 
 is of a reddish tint. It is probable that in the process 
 of tanning, the matter of skin, and the tanning princi- 
 ple first enter into union, and that the leather at the mo- 
 ment of its formation unites to the extractive matter. 
 
 In general, skins in being converted into leather in- 
 crease in weight about one third ;* and the operation is 
 most perfect when they are tanned slowly. When skins 
 are introduced into very strong infusions of tannin, the 
 exterior parts immediately combine with that principle, 
 and defend the interior parts from the action of the so- 
 lution ; such leather is liable to crack and to decay by 
 the action of water. 
 
 The precipitates obtained from infusions containing 
 tannin by isinglass, when dried, contain at a medium 
 rate about 40 per cent, of vegetable matter. It is easy 
 to obtain the comparative value of different substances 
 for the use of the tanner, by comparing the quantities 
 of precipitate afforded by infusions of given weights 
 mixed with solutions of glue or isinglass. 
 
 To make experiments of this kind, an ounce or 480 
 grains of the vegetable substance in coarse powder, 
 should be acted upon by half a pint of boiling water. 
 The mixture should be frequently stirred, and suffered 
 to stand 24 hours ; the fluid should then be passed through 
 a fine )inen cloth and- mixed with an equal quantity of 
 solution of gelatine, made by dissolving glue, jelly, or 
 isinglass in hot water, in the proportion of a drachm of 
 glue or isinglass, or six table spoonfuls of jelly, to a 
 pint of water. 'Vha precipitate should be collected by 
 passing the mixture of the solution and infusion through 
 folds of blotting paper ; and the paper exposed to the 
 air till its contents are quite dry. If pieces of paper 
 
 * Tliis estimation must be considered as applying to dry skin and 
 .-/rv leather. 
 
67 
 
 of equal weights are used, in cases iu Avhich different 
 vegetable substances are employed, the ditlerence of the 
 weights of the papers when dried, will indicate with 
 tolerable accuracy, the quantities of tannin contained by 
 the substances, and their relative value, for the purposes 
 of manufacture. Four tenths of the increase of weight, 
 in grains, must be taken, which will be in relation to 
 the weights in the table. 
 
 Besides the barks already mentioned, there are a num- 
 ber of others which contain the tanning principle. Few 
 barks indeed are entirely free from it. It is likewise 
 found in the wood and leaves of a number of trees and 
 shrubs, and is one of the most generally diffused of the 
 vegetable principles. 
 
 A substance very similar to tannin has been formed 
 by Mr. Hatchett, by the action of heated diluted nitric 
 acid on charcoal, and evaporation of the mixture to 
 dryness. From 100 grains of charcoal Mr. Hatchett 
 obtained 120 grains of artificial tannin, which, like na- 
 tural tannin, possessed the property of rendering skin 
 insoluble in vi^ater. 
 
 Both natural and artificial tannin form compounds 
 with the alkalies and the alkaline earths ; antl these 
 compounds are not decomposable by skin. The attempts 
 that have been made to render oak bark more efficient 
 as a tanning material by infusion in lime water, are con- 
 sequently founded on erroneous principles. Lime forms 
 with tannin, a compound not soluble in water. 
 
 The acids unite to tannin, and produce compounds 
 that are more or less soluble in water. It is probable 
 that in some vegetable substances tannin exists, combi- 
 ned with alkaline or earthy matter; and such substan- 
 ces will be rendered more efficacious for the use of the 
 tanner, by the action of diluted acids. 
 
 9. Indigo may be procured from woad [Tsatis tincto- 
 ria,) by digesting alcohol on it, and evaporating the so- 
 lution. White crystalline grains are obtained, which 
 gradually become blue by the action of the atmosphere : 
 these grains are the substance in question. 
 
 The indigo of commerce is principally brought from 
 America. It is procured from the Indigofera argenteUy 
 or wild indigo, the Indigofera disperma, or Gautimala 
 
indigo, ami the liidigofera tinctoria, or French indigo. 
 It is prepared by fermenting the leaves of those trees 
 in water. Indigo in its common form appears as a fine, 
 deep blue powder. It is insoluble in water, and but 
 slightly soluble in alcohol: its true solvent is sulphuric 
 acid : eight parts of sulphuric acid dissolve one part of 
 indigo ; and tlie solution diluted with water forms a 
 very line blue dye. 
 
 Indigo, by its distillation, affords carbonic acid gas, 
 water, charcoal, ammonia, and some oily and acid mat- 
 ter : tlie charcoal is in very large proportion. Pure in- 
 digo therefore most probably consists of carbon, hydro- 
 gene, oxygene, and azote. 
 
 Iiidigo owes its blue colour to combination with oxy- 
 gene. For the uses of the dyers it is partly deprived 
 of oxygene, by digesting it with orpiment and lime wa- 
 ter, when it becomes soluble in the lime water, and of 
 a greenish colour. Cloths steeped in this solution com- 
 bine with the indigo ; they are green when taken out of 
 the liquor, but become blue by absorbing oxygene when 
 exposed to air. 
 
 Indigo is one of the most valuable and most extensive- 
 ly used of the dyeing materials. 
 
 10. The narcotic principle is found abundantly in 
 opzM?/?, which is obtained fi'om the juice of the white pop- 
 py [Papaver album.) To procure the narcotic principle, 
 Avater is digested upon opium: the solution obtained is 
 evaporated till it becomes of the consistence of a syrup. 
 By the addition of cold water to this syrup a precipitate 
 is obtained. Alcohol is boiled on this precipitate ; du- 
 ring the cooling of the alcohol crystals fall down. These 
 crystals are to be again dissolved in alcohol, and again 
 precipitated by cooling : and the process is to be repeat- 
 ed till their colour is white; they are crystals of narco- 
 tic principle. 
 
 The narcotic principle has no taste nor smell. It is 
 soluble in about 400 parts of boiling water; it is insolu- 
 ble in cold water : it is soluble in 24 parts of boiling 
 alcohol, and in 100 parts of cold alcohol. J t is very 
 soluble in all acid menstrua. 
 
 It has been shewn by De Rosne, that the action of 
 opium on the animal economy depends on this principle.. 
 
69 
 
 Many other substances besides the juice of the poppy, 
 possess narcotic properties ; but they have not yet been 
 examined with much attention. The Lactuta sativa, 
 or garden lettuce, and most of the other lactucas yield 
 a milky juice, which when inspissated has the charac- 
 ters of opium, and probably contains the same narcotic 
 principle. 
 
 11. The hitter 'principle is very extensively diffused 
 in the vegetable kingdom ; it is found abundantly in the 
 hop [Humilus lupilus,) in the common broom [Spartium 
 scoparium,) in the chamomile [Anthemis nobilis,) and in 
 quassia, amara and excelsa. It is obtained from those 
 substances by the action of water or alcohol, and eva- 
 poration. It is usually of pale yellow colour ; its taste 
 is intensely bitter. It is very soluble, both in water and 
 alcohol ; and has little or no action on alkaline, acid, 
 saline, or metallic solution. 
 
 An artificial substance, similar to the bitter principle, 
 has been obtained by digesting diluted nitric acid, on 
 silk, indigo, and the wood of the white willow. This 
 substance has the property of dyeing cloth of a bright 
 yellow colour ; it differs from the natural bitter princi- 
 ple in its power of combining with the alkalies : in 
 union with the fixed alkalies it constitutes crystallized 
 bodies, which have the property of detonating by heat 
 or percussion. 
 
 The natural bitter principle is of great importance in 
 the art of brewing; it checks fermentation, and pre- 
 serves fermented liquors; it is likewise used in medicine. 
 
 The bitter principle, like the narcotic principle, ap- 
 pears to consist principally of carbon, hydrogene and 
 oxygene, with a little azote. 
 
 12. Wax is found in a number of vegetables ; it is 
 procured in abundance from the berries of the wax myr- 
 tle [Myrica cerifera:) it may be likewise obtained from 
 the leaves of many trees; in its pure state it is white. Its 
 specific gravity is 9,662 ; it melts at 155 degrees ; it is 
 dissolved by boiling alcohol ; but it is not acted upon by 
 cold alcohol ; it is insoluble in water ; its properties as 
 a combustible body are well known. 
 
 The wax of the vegetal)le kingdom seems to be pre- 
 riselvof the same nature as that afforded bv the bee. 
 
From the experiments of M. M. Gray Lusf^ac and The- 
 nard, it appears that 100 parts of wax consist of , 
 
 Carbon - - - - 81,784 
 Oxygene - - ' - - 5,544 
 
 Hydrogene - - - 12,672 
 
 Or otherwise, 
 
 Carbon .... 81,784 
 Oxygene and hydrogene in the ^ 
 
 proportions necessary to form \ 6,300 
 
 water ... ^ 
 
 Hydrogene - - - 11,916 
 
 which agrees very nearly with 37 proportions of hydro- 
 gene, 21 of charcoal, one of oxygene. 
 
 13. Resin is very common in the vegetable kingdom. 
 One of the most usual species is that aftbrded by the dif- 
 ferent kinds of fir. When a portion of the bark is re- 
 moved from a fir tree in spring, a matter exudes, which 
 is called turpentine ; by heating this tui-pentine gently, 
 a volatile oil rises from it, and a more fixed substance 
 remains, this substance is resin. 
 
 The resin of the fir is the substance commonly known 
 by the name of rosin ; its properties are well known. 
 Its specific gravity is 1072. It melts readily, burns 
 witli a yellow light, throwing off much smoke. Resin 
 is insoluble in water, either hot or cold ; but very solu- 
 ble in alcohol. When a solution of resin in alcohol is 
 mixed with water, the solution becomes milky ; the re- 
 sin is deposited by the stronger attraction of the water 
 for the alcohol. 
 
 Resins are obtained from many other species of trees. 
 Mastich, from the Fistachia lentiscus. Elemi from the 
 Amyris elemifera, Copal from the Rhus copallinum, San- 
 darach from the common juniper. Of these resins copal 
 is the most peculiar. It is the most difficultly dissolved 
 in alcohol ; and for this purpose must be exposed to that 
 substance in vapour; or the alcohol employed must hold 
 camphor in solution. Accordins; to Gray Lussac and 
 Thenard, 
 
rt 
 
 100 parts of cotiimou resin contain 
 
 
 Carbon 
 
 - 
 
 - 
 
 75,944 
 
 Oxygene - 
 
 - ■ 
 
 - 
 
 13,337 
 
 Hydrogene 
 
 - 
 
 - 
 
 10,719 
 
 or of 
 
 
 
 
 Carbon 
 
 - 
 
 - 
 
 75,944 
 
 Oxygene and 
 
 hydrogene in 
 
 the) 
 
 
 proportions 
 
 necessary to form } 
 
 15,156 
 
 water 
 
 - 
 
 ) 
 
 
 Hydrogene in 
 
 excess 
 
 
 8,900 * 
 
 According to the same cliemists, 
 
 100 
 
 parts of copal 
 
 consist of 
 
 
 
 
 Carbon 
 
 - 
 
 - 
 
 76,811 
 
 Oxygene 
 
 - 
 
 - 
 
 10,606 
 
 Hydrogene 
 
 - 
 
 - 
 
 12,583 
 
 01, 
 
 Carbon 
 
 - 
 
 - 
 
 76,811 
 
 Water or its elements 
 
 - 
 
 12,052 
 
 Hydrogene 
 
 - 
 
 - 
 
 11,137 
 
 From these results if resin be a definite compound, it 
 may be supposed to consist of eight proportions of car- 
 bon, twelve of hydrogene, and one of oxygene. 
 
 Resins are used for a variety of purposes. Tar and 
 pitch principally consist of resin, in a partially decom- 
 posed state. Tar is made by the slow combustion of the 
 fir 5 and pitch by the evaporation of the more volatile 
 parts of tar. Kesins are employed as varnish, and for 
 these purposes are dissolved in alcohol or oils. Copal 
 forms one of the finest. It may be made by boiling it 
 in powder with oil of rosemary, and tlien adding alco- 
 hol to the solution. 
 
 14. Camphor is procured by distilling the wood of the 
 camphor tree ( Laiirus camplwra,) which grows in Ja- 
 pan. It is a very volatile body, and may be purified 
 by distillation. Camphor is a white, brittle, semitrans- 
 parent substance, having a peculiar odour, and a strong 
 acrid taste. It is very slightly soluble in water ; more 
 than 100,000 parts of water arc required to dissolve one 
 pai't of camphor. It is very soluble in alcohol ; and by 
 adding water in small quantities at a time to the solu- 
 tion of camphor in alcohol, the camphor separates in a 
 
crystallized i'onu. It is soluble in nitric acid, and is se- 
 parated IVoiu it by water. 
 
 Cainplior is very inllanunabic ; it burns witli a bris;ht 
 flame, autl tlirows olV a j;Teat quantity of carbonaceous 
 matter. It forms in combustion water, carbonic acid, 
 and a peculiar acid called ciuuplioric acid. No accur 
 rate analysis has been made of campbcu-, but it st^.ems to 
 approach to the resins in its composition ; and consists of 
 carbou, bydroj;'eue, aud oxysjene. 
 
 Camphor exists in other plants besides the Lauims 
 camjjltora. It is procured from sjiecies of the laurus 
 j;ro\viu:i;* in Sumatra, Horneo, and other of the Kast 
 Indian isles. It has been obtained from thyme {Thy- 
 mus scv^iUnnu[ nuirjorum [Origanum majorana,) Gin- 
 p;er tree [Jlmmuntn Zingiber y) Saa;e [Salvia afficlna- 
 //.s'.) Many volatile oils yield camphor by being mere- 
 ly exposed to the air. 
 
 An artificial substance very similar to camphor has 
 been iVuined by M. Kind, by saturating; oil of turpen- 
 tine with muriatic acid gas (the gaseous substance pro- 
 cured from connuon salt by the action of sulphuric 
 acid.) The cami)hor procured in well conducted ex- 
 ])eriments amounts to half of the oil of turj)entine used. 
 It agrees with common camphor in most of its sensible 
 j»roperties ; but ditl'ers materially in its chemical (puili- 
 ties aud composition. It is not soluble without decom- 
 position in nitric acid. From the experiments of Geh- 
 len, it appears to consist of the elements of oil of tur- 
 pentine, carbon, hydrogene and oxygene, united to the 
 elements of nuniatic gas, chlorine aud hydrogene. 
 
 From the analogy of artilicial to natural camphor, it 
 does not appear improbable, that natural cami)hor may 
 be a secondary vegetable compound, consisting of cam- 
 phoric acid ami volatile oil. Camphor is used medici- 
 nally, but it has no other application. 
 
 15. Fidrd oil is obtained by expression from seeds 
 and fruits: the olive, the almond, linseed and rape-seed 
 atVord the nu)st common vegetable fixed oils. The pro- 
 perties of fixed oils are well known. Their specific 
 gravity is less than that of w ater ; that of olive and of 
 rape-seed oil is 91o; that of linseed and almond oil 932; 
 that of palm oil 9t>8 : that of walnut aud beech mast oil 
 
73 
 
 923. Many of the fixed oils congeal at a lower lem|)e- 
 rature tiian tliat at which water freezes. They all require 
 for tlieir eva|)oration a hii;lier temperature tliari that at 
 which water l)oils. The [iroducts of tlie combustion of 
 oil are water, and carbonic acid i;as. 
 
 From the exj)erimcnts of (jiay Lussac and Thenard, it 
 appears tiiat olive oil contains in 100 parts, 
 
 Carbon - - 77,213 
 
 Oxygenc - - 9,427 
 
 Hydrogenc - - 13,360 
 
 This estimation is a near aproximation to 11 propor- 
 tions of carbon, 20 hydrogene, and one oxyjjjenc;. 
 
 The following is a list of fixed oils, and of the trees 
 that aflord them. 
 
 Olive oil, from the Olive tree {Olea Europea,) Lin- 
 seed oil, from the common and Perennial Flax [Linum 
 2isitatisitimum et percnne,) Nut oil, from the lla/el nut 
 [Covyllus avellana,) Walnut, [Jui^lans regia,) Hemp 
 oil, from the Hemp [Cannahis sativay) Almond oil from 
 the sweet Almond, (Jlmy/^'duhis communisy) Heech oil, 
 from the common Beech [Fai^us sylvatica^) Rape-seed 
 oil, from the Rapes {^BrasHica najms et campeatriH,) Pop- 
 py oil, from the Poppy [PapavGv aomnifcvum,) oil of 
 Sesamum, from the Sesamum (Seftamum orientate,) 
 Cucumber oil, from the Gourds [CucuThita pepo etma- 
 leppo,) oil of Mustard, from the Mustard [Sinaph ni- 
 gra et arvensin,) oil of Sunflower, from the annual and 
 perennial Sunflower, [Jlelianflius annuus et perennis,) 
 Castor Oil, from the Palma Christi [Ricinun commu- 
 nis,) Tobacco-seed oil, from the Tobacco {J^Ticotiana 
 fabacum et rustica,) Plum kernel oil, from the Plum 
 tree {Prunus domeHtica,) (Irape-seed oil, from the Vine 
 ( Vitia vinifera,) Rutter of cacoa, from tli(5 Cacoa tree 
 [Theobroma cacao,) Laurel oil, from the sweet Ray tree 
 [Lauras nobilis,) 
 
 The fixed oils are very nutritive substances; they are, 
 of great importance in their applications to the purposes 
 of life. Fixed oil, in combination with soda, forms the 
 finest kind of hard soap. The fixed oils are used ex- 
 tensively in tlnMiiiM hani(;al arts, and for the preparati<m 
 of pigments and varnishes. 
 
 IG. J'ulaUhi oil, likewise calhid essenliul ail. diflers 
 
 K 
 
74 
 
 from fixed oil, in being capable of evaporation by a much 
 lower <U'i:;rec of lieat ; in being soluble in alcohol, and 
 in possessing a very slight degree of solubility in wa- 
 ter. 
 
 There is a great number of volatile oils, distinguish- 
 ed by their smell, their taste, their specific gravity, and 
 other sensible qualities. A strong and peculiar odour 
 may however be considered as the great characteristic of 
 each species ; the volatile oils inflame with more facility 
 than the fixed oils, and afford by their combustion dif- 
 ferent proportions of the same substances, water, car- 
 bonic acid, and carbon. 
 
 The following specific gravities of different \olatile 
 oils were ascertained by Dr. Lewis. 
 
 Oil of Sassafras - - - 1094 
 
 Cinnamon - - - 1035 
 
 Cloves ... . 1034 
 
 Fennel - - - 997 
 
 Dill . - . . 994 
 
 Penny Royal - - 978 
 
 Cummin - - - 975 
 
 Mint - - - - 975 
 
 Nutmegs - - - 948 
 
 Tansy - - - 946 
 
 Carraway - - - 940 
 
 Origanum - - - 940 
 
 Spike - - - - 936 
 
 Rosemary - - - 934 
 
 Juniper - - - 911 
 
 Oranges - - - 888 
 
 Turpentine - - - 792 
 
 The peculiar odours of plants seem, in almost all ca- 
 ses, to depend upon the peculiar volatile oils they con- 
 tain. All the perfumed distilled waters owe their pe- 
 culiar properties to the volatile oils they hold in solu- 
 tion. By collecting the aromatic oils, the fragrance of 
 flowers, so fugitive in the common course of nature, is 
 as it were embodied and made permanent. 
 
 It cannot be doubted that the volatile oils consist of 
 carbon, hydrogene, and o\y;;ene ; but no accurate ex- 
 
75 
 
 j)erinieiits have as yet been made on the proportions in 
 which these elements are combined. 
 
 The volatile oils have never been used as articles ol* 
 food ; many of them are employed in the arts, in the 
 manufacture of pii^ments and varnishes ; but their most 
 extensive application is as perfumes. 
 
 17. Woody fibre is procured from the wood, bark, 
 leaves, or flowers of trees, by exposing them to the re. 
 peated action of boiling water and boiling alcohol. It 
 is the insoluble matter that remains, and is the basis of 
 the solid organized parts of plants. There are as ma- 
 ny varieties of woody fibre as there are plants and or- 
 gans of plants ; but they are all distinguished by their 
 fibrous- texture, and their insolubility. 
 
 Woody fibre burns with a yellow flame, and produces 
 water and carbonic acid in burning. When it is distil- 
 led in close vessels, it yields a considerable risiduum of 
 charcoal. It is from woody fibre, indeed, that charcoal 
 is procured for the purposes of life. 
 
 The following table contains the results of experi- 
 ments made by Mr. Mushet, on the quantity of charcoal 
 aiforded by difi*erent wood. 
 
 100 parts of Lignum Vitae - 26,8 of charcoal 
 
 Mahogany - 2.5,4 
 
 ■ Laburnum - 24,5 
 
 Chesnut - - 23,2 
 
 ~ Oak - - - 22,6 
 
 American black 
 
 Beech - - 21,4 
 
 Walnut - - 20,6 
 
 Holly - ' - 19,9 
 
 Beech - - 19,9 
 
 American Maple 19,9 
 
 Elm - - 19,5 
 
 Norway Pine - 19,2 
 
 Sallow - - 18,4 
 
 Ash - - 17,9 
 
 Birch - - 17,4 
 
 Scottish Fir - 16,4 
 
 M. Gay Lussac and Thenard have concluded from 
 
Hioii' experiments on the wood of the oak and the beech, 
 that 100 parts of the first contain : 
 
 Of Carbon 
 
 — Oxygenc 
 
 — Hydrogcne 
 
 52,53 
 
 41,78 
 
 5,69 
 
 •ts of the second : 
 
 
 Of Carbon 
 
 — Oxyi^enc 
 
 — Hydrogcne 
 
 51,45 
 42,7.5 
 
 5,82 
 
 Snpposing woody fibre to be a definite compound, 
 tliese estimations lead to the conclusion, tlnit it consists 
 (»f five proportions of carbon, tin-ec of oxygene, and six 
 of hydrogcne ; or 57 carbon, 45 oxygene, and six hy- 
 drogcne. 
 
 It w ill be unnecessary to speak of the applications of 
 Avoody fibre. The diflerent uses of the woods, cotton, 
 linen, the barks of trees are sufficiently known. Woody 
 fibre appears to be an indigestible substance. 
 
 18. Tlie acids found in the vegetable kingdom are 
 numerous ; the true vegetable acids which exist ready 
 formed in the juices or organs of plants, are the oxalic, 
 citric, tartaric, benzoic, acetic, malic, gallic, and prus- 
 sic acid. 
 
 All these acids, except the acetic, malic, and prussic 
 acids, are white crystallized bodies. The acetic, malic, 
 and prussic acids liave been obtained only in the fluid 
 state ; they are all more or less soluble in water ; all 
 have a sour taste except the gallic and prussic acids ; 
 of which the first has an astringent taste, and the latter 
 a taste like that of bitter almonds. 
 
 The oxalic acids exists, uncombined, in the liquor 
 which exudes from the Chich pea [Cicer arietinunu) 
 and may be procured from wood sorrel ( O.valis acetosel- 
 la,) common sorrel, and other species of Uumex ; and 
 from the Geranium acidum. Oxalic acid is easily dis- 
 covered and distinguished from other acids by its pro- 
 perty of decomposing all calcareous salts, and forming 
 with lime a salt insoluble in water ; and by its crystal- 
 lizing in fouT-sided prisms. 
 
Tiie citric acid is the peculiar acid existing in the 
 juice of lemons and oranges. It may likwLse be obtain- 
 ed from the cranbery, whortleberry, and hip. 
 
 Citric acid is distinguished by its forming a salt inso- 
 luble in water with lime ; but decomposable by the mi- 
 neral acids. 
 
 The tartaric acid may be obtained from the juice of 
 mulberries and grapes ; and likewise from the pulp of 
 <he tamarind. It is characterised by its property of 
 forming a difficultly soluble salt with potassa, and an 
 insoluble salt decomposable by the mineral acids with 
 lime. 
 
 Benzoic acid may be procured from several resinous 
 substances by distillation ; from benzoin, storax, and 
 balsam of Tolu. It is distinguished from the other 
 acids by its aromatic odour, and by its extreme vola- 
 tility. 
 
 Malic acid maybe obtained from the juice of apples, 
 barberries, plums, elderberries, currants, strawberries, 
 and raspberries. It forms a soluble salt with lime; and 
 is easily distinguished by this test from the acids alrea- 
 dy named. 
 
 Acetic acid, or vinegar, may be obtained from the 
 sap of different trees. It is distinguished from malic 
 acid by its peculiar odour ; and from the other vegeta- 
 ble acids by forming soluble salts with the alkalies and 
 earths. 
 
 Gallic acid may be obtained by gently and gradually 
 heating powdered gall-nuts, and receiving the volatile 
 matter in a cool vessel. A number of white crystals 
 will appear, which are distinguished by their property 
 of rendering solutions of iron, deep purple. 
 
 The vegetable prussic acid is procured by distilling 
 laurel leaves, or the kernels of the peach, and cherry, 
 or bitter almonds. It is characterized by its property 
 of forming a blueish green precipitate, when a little al- 
 kali is added to it, and it is poured into solutions con- 
 taining iron. It is very analogous in its properties to 
 the prussic acid obtained from animal substances ; or by 
 passing ammonia over heated charcoal ; but tliis last 
 body forms, with the red oxide of iron, tlie deep, bright 
 blue substance, called Prussian blue. 
 
7-8 
 
 Two other vegetable acids have been found in the 
 products of plants ; the morolyxic acid in a saline exu- 
 dation from the white mulberry tree, and the kinic acid 
 in a salt afforded by Peruvian bark; but these two 
 bodies have as yet been discovered in no other cases. 
 The phosphoric acid is found free in the onion ; and the 
 phosphoric, sulphuric, muriatic, and nitric acids, exist 
 in many saline compounds in the vegetable kingdom ; 
 but they cannot with propriety be considered as vegata- 
 ble products. Other acids are produced during the com- 
 bustion of vegetable compounds, or by the action of ni- 
 tric acid upon them ; they are the camphoric acid, the 
 mucous or saclactic acid, and the suberic acid ; the first 
 of which is procured from camphor ; the second from 
 gum or mucilage; and the third from cork,by the action 
 of nitric acid. 
 
 From the experiments that have been made upon the 
 vegetable acids, it appears that all of them, except the 
 prussic acid, are constituted by different proportions of 
 carbon, hydrogene, and oxygene ; the prussic acid con- 
 sists of carbon, azote, and hydrogene, with a little oxy- 
 gene. The gallic acid contains more carbon than any 
 of the other vegetable acids. 
 
 The following estimates of the composition of some 
 of the vegetable acids have been made by Gay Lussac 
 and Thenard. 
 
 100 parts of oxalic acid contain : 
 
 Carbon - - 26,566 
 Hydrogene - 2,745 
 
 Oxygene - - 
 
 70,689 
 
 Ditto of Tartaric acid: 
 
 
 Carbon - - 
 
 24,050 
 
 Hydrogene - 
 
 6,629 
 
 Oxygene - - 
 
 69,321 
 
 Ditto citric acid : 
 
 
 Carbon - - 
 
 33,811 
 
 Hydrogene - 
 
 6,330 
 
 Oxygene - - 
 
 59,859 
 
 Ditto acetic acid : 
 
 
 Carbon - - 
 
 50,224 
 
 Hydrogene - 
 
 5,629 
 
 Oxygene - - 
 
 44.147 
 
79 
 
 100 parts of mucous or saclactic acid : 
 Carbon - - 33,69 
 Hytlrogene - - 3,62 
 Oxygene - 62,69 
 
 These estimations agree '•nearly with the following de- 
 finite proportions. In oxalic acid 7 proportions of car- 
 bon, 8 of hydrogene, and 15 of oxygene ;* in citric 
 acid, 8 carbon, 28 hydrogene, 18 oxygene; in acetic 
 acid, 3 carbon, 6 hydrogene, 4 oxygene; in acetic acid, 
 18 carbon, 22 hydrogene, 12 oxygene ; in mucous acid, 
 6 corbon, 7 hydrogene, 8 oxygene. 
 
 The applications of the vegetable acids are well 
 known. The acetic and citric acids are extensively used. 
 The agreeable taste and wholesomeness of various ve- 
 getable substances used as food, materially depend up- 
 on the vegetable acid they contain. 
 
 19. Fixed alkali may be obtained in acqueous solu- 
 tion from most plants by burning them, and treating the 
 ashes with quick lime and watei*. The vegetable alkali, 
 or potassa, is the common alkali in the vegetable king- 
 dom. This substance in its pure state is white, and 
 semi-transparent, requiring a strong lieat for its fusion, 
 and possessed of a highly caustic taste. In the matter 
 usually called pure potassa by chemists, it exists com- 
 bined with water, and in that commonly called pearl 
 ashes, or potashes in commerce, it is combined with a 
 small quantity of carbonic acid. Potassa in its uncora- 
 bined state, as has been mentioned, page 89, consists of 
 the highly inflammable metal potassium, and oxygene, 
 one proportion of each. 
 
 Soda,, or the mineral alkali, is found in some plants 
 that grow near the sea ; and is obtained combined with 
 water, or carbonic acid, in the same manner as potassa ; 
 and consists, as has been stated, page 39, of one pro- 
 portion of sodium, and two proportions of oxygene. 
 In its properties it is very similar to potassa : but may 
 be easily distinguished from it by this character : it forms 
 a hard soap with oil : potassa forms a soft soap. 
 
 * Accordinj^ to Dr. Thomson's experiments, oxalic acid consists of 
 3 proportions of carbon, 4 of oxyt^ene, and 4 of liydrogene., a rchul!: 
 "cry different indeed from that of the French chemists. 
 
80 
 
 Pearl ashes, and barilla and kelp, or the impure soda 
 obtained from the ashes of marine plants, are very va- 
 luable in commerce, principally on account of their 
 uses in the manufacture of glass and soap. Glass is 
 made from fixed alkali, flint, and certain metallic sub- 
 stances. 
 
 To know whether a vegetable yields alkali, it should 
 be burnt, and the ashes washed with a small quantity 
 of water. If the water, after being for some time ex- 
 posed to the air, reddens paper tinged with turmeric : 
 or renders vegetable blues, green, it contains alkali. 
 
 To ascertain the relative quantities of pot-ashes af- 
 forded by difi'erent plants, equal weights of them should 
 be burnt : the ashes washed in twice their volume of 
 water ; the washings should be passed through blotting 
 paper and evaporated to dryness : the relative weights 
 of the salt obtained will indicate very nearly the rela- 
 tive quantities of alkali they contain. 
 
 The value of marine plants in producing soda, may 
 be estimated in the same manner, with sufficient correct- 
 ness for all commercial purposes. 
 
 Herbs, in general, furnish four or five times, and 
 shrubs two or three times as much pot-ashes as trees. 
 The leaves produce more than the branches, and the 
 branches more than the trunk. Vegetables burnt in a 
 green state produce more ashes than in a dry state. 
 
 The following table* contains a statement of the quan- 
 tity of pot-ashes afforded by some common trees and 
 plants. 
 
 10,000 parts of Oak . - - 15 
 
 of Elm - - - 39 
 
 of Beech - - 12 
 
 of Vine - - 55 
 
 of Poplar - - 7 
 
 of Thistle - - 53 
 
 of Fern - - - 62 
 
 of Cow Thistle 196 
 
 of WormAvood 730 
 
 — of Vetches - - 275 
 
 * It is founded upon the experiments of Kirwan, Vauquelin, and 
 Pcitiiis. 
 
81 
 
 10,000 parts of Beans - - 200 
 of Fumitory - 790 
 
 The eqrths found in plants are four : silica or ilie 
 earth of flints, alumina or pure clay, lime, and magne- 
 sia. They are procured by incineration. The lime is 
 usually combined with carbonic acid. This substance 
 and silica are much more common in the vegetable king- 
 dom than magnesia, and magnesia more common than 
 alumina. The earths form a principal part of the mat- 
 ter insoluble in water, afforded by the ashes of plants. 
 The silica is known by not being dissolved by acids ; 
 the calcareous earth, unless the ashes have been very 
 intensely ignited, dissolves with effervescence in muria- 
 tic acid. Magnesia forms a soluble and crystallizable 
 salt, and lime, a difficultly soluble one with sulphuric 
 acid. Alumina is distinguished from the other earths, 
 by being acted upon very slowly by acids ; and in form- 
 ing salts very soluble in water, and difficult of crystalli- 
 zation with them. 
 
 The earths appear to be compounds of the peculiar 
 metals mentioned page 40, and oxygene, one proportion 
 of each. 
 
 The earths afforded by plants, are applied to no uses 
 of common life ; and there are few cases in which the 
 knowledge of their nature can be of importance, or af- 
 ford interest to the farmer. 
 
 The only metallic oxides found in plants are those of 
 iron and manganesum : they are detected in the ashes of 
 plants ; but in very minute quantities only. AVhen the 
 ashes of plants are reddish brown, they abound in oxides 
 of iron. When black or purple, in oxide of mangane- 
 sum ; when these colours are^ mixed, they contain both 
 substances. 
 
 The saline compounds contained in plants, or afford- 
 ed by their incineration, are very various. The sul- 
 phuric acid combined with potassa, or sulphate of po- 
 tassa, is one of the most usual. Common salt is like- 
 wise very often found in the ashes of plants ; likewise 
 phosphate of lime, which is insoluble in water, but solu- 
 ble in muriatic acid. Compounds of the nitric, muria- 
 tic, sulphuric, and phosphoric acids, with alkalies and 
 
 L 
 
82 
 
 earths, exist in the sap of many plants, or are afltbrded 
 by their evaporation and incineration. The salts of po- 
 tassa are distinguished from those of soda, by their pro- 
 ducing a precipitate in solutions of platina : those of 
 lime are characterized by the cloudiness they occasion 
 in solutions containing oxalic acid ; those of magnesia, 
 by being rendered cloudy by solutions of ammonia. 
 Sulphuric acid is detected in salts by the dense white 
 precipitate it forms in solutions of baryta. Muriatic 
 acid by the cloudiness it communicates to solution of 
 nitrat of silver; and when salts contain nitric acid, 
 they produce scintillations by being thrown upon burn- 
 ing coals. 
 
 As no applications have been made of any of the 
 neutral salts, or analogous compounds found in plants, 
 in a separate state, it will be useless to describe them 
 individually. The following tables are given from M. 
 Th. de Saussure's Researches on vegetation, and contain 
 results obtained by that philosopher. They exhibit the 
 quantities of soluble salts, metallic oxides, and earths 
 affordetl by the ashes of different plants. 
 
83 
 
 r-' 
 
 1*AMES OF PLANTS. 
 
 W OS, 
 
 O ^ 
 
 ** c 
 
 Leaves of oak {queruis 
 
 robur) May 10 - 
 
 Ditto. Sept. 27 
 
 VVood of a young oak, 
 
 May 10 
 
 Bark of ditto ...---.- 
 Entire wood of oak - - - - 
 Alburnum of ditto - - - - 
 Bark of ditto ...•••.. 
 Cortical layers of ditto - - 
 Extract of wood of ditto - 
 Soil from wood of ditto - 
 Extract from ditto - - - . 
 Leaves of the poplar {po- 
 pulus nigra) May 26 - 
 
 Ditto, Sept. 12 
 
 Wood of ditto, Sept. 12 - 
 
 Bark of ditto 
 
 Leaves of hazel (^coryhis 
 avelland) May 1 - - - • 
 Do. washed in cold water 
 Leaves of ditto, J une 22 
 
 Ditto, Sept. 20 
 
 Wood of ditto. May 1 - - 
 
 Bark of ditto 
 
 Entire wood of mulberry, 
 [tnorus nigra) Novem. 
 Alburnum of ditto - . • • 
 Bark of ditto -.-..... 
 Cortical layers of ditto - - 
 Entire wood of hornbeam, 
 {carpinus betulus,) Nov. 
 Alburnum of ditto - - • - 
 
 Bark of ditto 
 
 Wood of liorse chesnut, 
 [itsculus hyppocastanum) 
 
 May 10 
 
 Leaves of ditto. May 10 - 
 Leaves of ditto, July 23 • 
 
 Ditto, Sept. 27 
 
 Flowers of ditto. May 10 
 
 Fruit of ditto, Oct. 5 
 
 Plants of peas (^pisum sa- 
 tivum,) in flower - - - . 
 Plants of peas (^pisum sa- 
 tivum,) in flower, ripe 
 Plants of vetches, [vicia 
 faba,) before flowering, 
 
 May 23 
 
 Ditto in flower, June 23 - 
 Ditto ripe, July 23 - - - - 
 Ditto, seeds separated - - 
 
 Seeds of ditto 
 
 I Ditto in flower, raised in 
 I distilled water . • - • . 
 
 31 
 
 53 
 55 
 
 4 
 
 60 
 2 
 
 60 
 -3 
 61 
 41 
 111 
 
 66 
 
 93 
 
 8 
 
 72 
 
 61 
 57 
 62 
 70 
 5 
 62 
 
 7 
 13 
 
 89 
 88 
 
 150 
 
 122 
 
 66 
 
 115 
 
 33 
 
 39| 
 
 745 
 49 
 
 o ^ 
 
 652 
 
 565 
 
 26 
 
 655 
 557 
 
 340 
 390 
 346 
 
 782 
 652 
 630 
 873 
 647 
 
 895 
 876 
 
 Constituents of 100 Parts of 
 the Ashes. 
 
 47 
 17 
 
 26 
 7 
 
 38,6 
 32 
 
 7 
 
 7 
 51 
 24 
 66 
 
 36 
 26 
 
 24 
 18,25 
 
 28,5 
 4,5 
 4,5 
 
 24 
 3 
 3,75 
 
 10,5 
 
 26 
 8,2 
 22,7 
 11 
 24,5 
 
 21 
 
 26 
 
 7 
 
 10 
 
 22 
 18 
 
 4,5 
 
 9,5 
 50 
 24 
 13,5 
 50 
 82 
 
 49,8 
 
 34,25 
 
 55,5 
 
 55,5 
 
 50 
 
 42 
 
 69,28 
 
 60,1 
 
 13 
 
 7 
 16,75 
 
 5,3 
 
 23,3 
 19,5 
 14 
 12 
 35 
 5,6 
 
 2,25 
 27,25 
 
 8,6 
 16,5 
 
 23 
 36 
 4,5 
 
 0,12 
 
 23 
 
 12,25 
 
 63,25 
 
 32 
 
 11 
 
 06 
 
 65 
 
 10 
 
 29 
 36 
 27 
 60 
 
 22 
 44,1 
 29 
 36 
 8 
 54 
 
 53 
 24 
 45 
 
 48 
 
 26 
 15 
 59 
 
 12 
 
 17.25 
 
 22 
 
 14,5 
 13,5 
 17,75 
 5,75 
 27,92 
 
 30 
 
 3 
 14,5 
 
 0,12 
 
 0,25 
 
 2 
 
 7,5 
 
 1,5 
 
 0,5 
 
 32 
 
 5 
 11,5 
 
 3,3 
 
 4 
 
 2,5 
 4 
 11,3 
 
 22 
 0,25 
 0,25 
 
 0,12 
 1 
 15,25 
 0,12 
 
 0,12 
 
 1 
 
 1,5 
 
 0,64 
 1,75 
 
 1 
 
 1,75 
 2,25 
 2 
 
 14 
 
 25,24 
 
 ,58 
 22,75 
 2;),65 
 23,5 
 21,5 
 22,75 
 
 8,5 
 
 1,25 15,75 
 1,5 18 
 
 3,5 
 4,12 
 4 
 36 
 
 0,5 
 2,3 
 11 
 
 1,5 
 1,5 
 1,75 
 1,75 
 
 1,5 
 1,5 
 
 1,5 
 
 2 
 
 1,5 
 
 o 
 
 0,12 
 1,75 
 
 0,25 
 0,25 
 1,12 
 1 
 
 2,25 
 
 1 
 
 0,12 
 
 24,5 
 23,2 
 
 24,7 
 
 22,2 
 
 21,5 
 
 17 
 
 32,2 
 
 26 
 
 20,38 
 21,5 
 23,13 
 24,38 
 
 26,03 
 
 29 
 
 30,38 
 
 0,25 
 
 I 
 
 2,5 
 
 0,5 
 0,5 
 0,5 
 1 
 
 0,5 
 
 0,5 
 
 5,25 
 24,65 
 17,25 
 
 24,50 
 24,38 
 2*5 
 12.9 
 2,3 
 
 9.4 
 
84 
 
 68 
 
 69 
 
 7.5 
 
 NAMES OF PLANTS. 
 
 Solvdago Tii/ifuviii, bttbn; 
 
 ili)«criiip;, JVliiy 1 
 
 Ditto, just it) llowtT, July 
 
 If. .' 
 
 Ditto, seeds n|)c, Sept. 20 
 
 I'hints of tunisol [lieliim- 
 
 thus (11171 iivx,) !» mouth 
 
 hctbrc llowering, June 
 
 '2'.i 
 
 Ditto ill flower, July 23 - 
 Ditto, boni'iiig r\\n\ seetls, 
 
 Sipt. '*(! 
 
 Wheal {triticiim sativum) 
 
 in flower --.-..--. 
 
 Ditto, seeds rijie --..-- 
 
 Ditto, ft mouth before 
 
 flowering ---....-. 
 
 Ditto, in flower, June 14 - 
 Ditto, seeds ripe ----- 
 
 Straw (if wheat ------ 
 
 Seeds of ditto ------- 
 
 Uran 
 
 Plants of maize (zen mays) 
 a month before flower- 
 ing, June 23 ------ - 
 
 Ditto, ill flower, July 23 - 
 Ditto, seeds ripe ------ 
 
 Stalks of ditto 
 
 Spikes of ditto ------- 
 
 Seeds of ditto - 
 
 ChatVof Ijarley [hordeum 
 
 viilffiirc) -.----., 
 Seeds of ditto ---.-. 
 
 Ditto 
 
 Oats , 
 
 Leaves of r/tododendrov 
 fcrnigincvin, raised on 
 Jura, a limestone muini 
 
 tain, June 20 
 
 Leaves of rhododendroti 
 formqinni})!, raised on 
 Hreven, a granitic nioun 
 tain, June '27 ------ - 
 
 Hranches of ditto, June 
 
 20 
 
 Spikes of tlitto, June 27 
 Leaves of tir [pi/nis abirx) 
 raised on Jura, June 20 
 Ditto, r;used on Bixven, 
 June 27 -------- . 
 
 Brnnclies of Jiine, June 20 
 
 W hoi't leherry ,(T(7ftv'«;7/«i 
 
 myrti/liis,) raised on Jh 
 
 ra, Aug. 29 
 
 Ditto, raised on Biv.ven - 
 
 
 IG 
 
 92 
 
 93 
 
 30 
 
 I- 
 
 el 
 
 pp.* 
 
 753 
 
 f.99 
 
 Constituents of 100 Paris of 
 the Ashes. ^ 
 
 f)7,.'; 
 
 59 
 48 
 
 f)3 
 (31 
 
 5,15 
 
 43,'25 
 11 
 
 GO 
 41 
 10 
 22,5 
 47,10 
 4,1C 
 
 69 
 69 
 
 2,45 
 
 02 
 
 20 
 29 
 
 28 
 
 .... 
 
 22 5 
 24 
 
 16 
 
 15 
 
 15 
 
 10,75 
 
 59 
 It 
 
 67 
 6 
 
 22,5 
 
 12,75 
 15 
 
 11,5 
 
 10,75 
 11,75 
 0,2 
 44,5 
 40,5 
 
 5,75 
 
 
 5 
 
 ;?6 
 
 7,7i 
 32,5 
 22 
 24 
 
 14 
 
 16,75 
 
 10 
 11.5 
 
 12,27 
 
 12 
 
 1,5 
 
 1,5 
 
 17,25 
 
 11,.5G 
 12,5 
 
 0,25 
 
 0,25 
 
 0,25 
 0,25 
 0.25 
 1 
 
 0,25 
 0,25 
 
 12,5 
 
 43,25 
 
 16,75 
 
 39 
 29 
 
 'i;3,5 
 
 29 
 
 42 
 
 1,5 
 1,5 
 
 .3,75 
 
 32 
 54 
 
 12,5 
 
 26 
 
 .■il 
 
 61,5 
 0,5 
 0,5 
 
 7,5 
 7,5 
 
 18 
 
 1 
 
 57 
 35,5 
 21 
 00 
 
 0,75 
 
 0,5 
 1 
 
 2,5 
 
 19 
 
 0,75 
 
 0,75 
 .1.5 
 
 0,12 
 0,12 
 
 0,5 
 
 0,5 
 1 
 
 0,25 
 
 0,5 
 
 0,75 
 
 I 
 
 0,25 
 
 0,25 
 
 0,25 
 0,25 
 
 0,5 
 
 0,12 
 
 t),5 
 0.25 
 0,12 
 11,25 
 
 3,25 
 
 5,77 
 
 5,4 
 11 
 
 1,6 
 
 5,5 
 
 0,5 3,12 
 5 9,5 
 
 18,25 
 
 21 
 18,75 
 
 16,07 
 18,78 
 
 17,75 
 
 12,25 
 18,75 
 
 15,5 
 
 21,5 
 
 23 
 
 8 
 
 7,6 
 8,6 
 
 17,25 
 17 
 
 3,05 
 
 0,88 
 
 2,25 
 
 2,8 
 
 29,S8 
 
 14,75 
 
 15,63 
 
 31,52 
 
 22,48 
 2V,5 
 
 2-1,13 
 
 19,5 
 
 1 9,38 
 17,5 
 
85 
 
 Besides the pnuciplcs, the nature of wliicli has been 
 just discussed, others have been described by chemi sts 
 as belonging to the vegetable kingdom : thus a substance, 
 somewhat analogous to the muscular iibre of animals, 
 has been detected by Vauqueliu iu the papavv ; and a 
 matter similar to animal gelatine by Braconnot in the 
 mushroom ; but in this place it would be improper to 
 dwell upon peculiarities ; ray object being to oiler such 
 general views of the constitution of vegetables as may 
 be of use to the agriculturist. Some distinctions have 
 been adopted l)y systematical authors wiiich I have not 
 entered into, because they do not appear to me essential 
 to this inquiry. Dr. Thomson, in his elaborate and 
 learned system of chemistry, has described six vegeta- 
 ble sul)stances, which he calls mucus, jelly, sarcocol, 
 asparagin, innlin, and ulmin. He states that mucus ex- 
 ists in its purest form in linseed ; but Vauquelin has 
 lately shewn, that the mucilage of linseed is, in its es- 
 sential characters, analogous to gum; but that it is com- 
 bined with a substance similar to animal mucus : vege- 
 table jelly. Dr. Thomson himself considers as a modifi- 
 cation of gum. It is probable, from the taste of sarco- 
 col, that it is gum combined with a little sugar. Inulin 
 is so analogous to starch, that it is probably a variety of 
 that principle : ulmin has been lately shewn by Mr. 
 Smithson to be a compound of a peculiar extractive mat- 
 ter and potasssa ; and as|)aragin is probably a similar 
 combination. If slight difterences in chemical and phy- 
 sical properties be considered as sufficient to establish 
 a diflerence in the species of vegetable substances, the 
 catalogue of them might be enlarged to almost any ex- 
 tent. No two compounds procured from dillerent vege- 
 tables are precisely alike ; and there are even difl'erences 
 in the qualities of the same compound, according to the 
 time in which it has been collected, and the manner in 
 which it has been prepared : the great use of classifica- 
 tion in science is to assist the memory ; and it ought to 
 be founded upon the similarity of properties which are 
 distinct, characteristic and invariable. 
 
 The analysis of any substance containing mixtures of 
 the diilerent vegetable principles, may be made in such 
 a manner as is necessary for the views of the agricultu- 
 
list with facility. A given quantity, say 200 grains, of 
 the substance should be powdered, made into a paste or 
 mass, with a small quantity of water, and kneaded in 
 the hands, or rubbed in a mortar for some time under 
 cold water ; if it contain much gluten, that principle will 
 separate in a coherent mass. After this process, whe- 
 ther it has afforded gluten or not, it should be kept in 
 contact with half a pint of cold water for three or four 
 hours, being occasionally rubbed or agitated : the solid 
 matter should be separated from the fluid by means of 
 blotting paper : the fluid should be gradually heated ; if 
 any flakes appear, they are to be separated by the same 
 means as the solid matter in the last process, i. e. by 
 filtration. Tlie fluid is then to be evaporated to dry- 
 ness. The matter obtained is to be examined by ap- 
 plying moist paper, tinged with red cabLage juice, or 
 violet juice to it ; if the paper become red, it contains 
 acid matter; if it become green, alkaline matter; and the 
 nature of the acid or alkaline matter may be known by 
 applying the tests described page 77, 78, 79. If the 
 solid matter be sweet to the taste, it must be supposed 
 to contain sugar; if bitterish, bitter principle, or extract; 
 if astringent, tannin : and if it be nearly insipid, it must 
 be principally gum or mucilage. To separate gum or 
 mucilage from the other principles, alcohol must be boil- 
 ed upon the solid matter, which will dissolve the sugar 
 and the extract, and leave the mucilage ; the weight of 
 which may be ascertained. 
 
 To separate sugar and extract, the alcohol must be 
 evaporated till crystals begin to fall down, which are su- 
 gar ; but they will generally be coloured by some ex- 
 tract, and can only be purified by repeated solutions in 
 alcohol. Extract may be separated from sugar by dis- 
 solving the solid, obtained by evaporation from alcohol, 
 in a small quantity of water, and boiling it for a long 
 while in contact with the air. The extract will gradu- 
 ally ftiU down in the form of an insoluble powder, and 
 the sugar will remain in solution. 
 
 If tannin exist in the first solution made by cold wa- 
 ter, its separation is easily effected by the process de- 
 scribed page 66. The solution of isinglass must be 
 gradually added, to prevent the existence of an excess 
 
87 
 
 of animal jelly in the solution, which might he mistaken 
 for mucilage. 
 
 When the vegetahle substance, the subject of experi- 
 ment, will afford no more principles to cold water, it 
 must be exposed to boiling water. This will unite to 
 starch if there be any, and may likewise take up more 
 sugar, extract, and tannin, provided they be intimately 
 combined with the other principles of the compound. 
 
 The mode of separating starch is similar to that of se- 
 parating mucilage. 
 
 If after the action of hot water any thing remain, the 
 action of boiling alcohol is then to be tried. This will 
 dissolve resinous matter ; the quantity of which may be 
 known by evaporating the alcohoL 
 
 The last agent that may be applied is ether, which 
 dissolves elastic gum, though the application is scarce- 
 ly ever necessary ; for if this principle be present, it 
 may be easily detected by its peculiar qualities. 
 
 If any fixed oil or wax exist in the vegetable substance, 
 it will separate during the process of boiling in water, 
 and may be collected. Any substance not acted upon 
 by water, alcohol, or ether, must be regarded as woody 
 fibre. 
 
 If volatile oils exist in any vegetable substances, it is 
 evident they may be procured, and their quantity ascer- 
 tained, by distillation. 
 
 When the quantity of fixed saline, alkaline, metallic, 
 or earthy matter in any vegetable compound is to be as- 
 certained, the compound must be decomposed by heat, 
 by exposing it, if a fixed substance, in a crucible, to a 
 long continued red heat ; and if a volatile substance, by 
 passing it through an ignited porcelain tube. The na- 
 ture of the matter so produced, may be learnt by apply- 
 ing the tests mentioned in page 81. 
 
 The only analyses in which the agricultural chemist 
 can often wish to occupy himself, are those of substan- 
 ces containing principally starch, sugar, gluten, oils, mu- 
 cilage, albumen, and tannin. 
 
 The two following statements will afford an idea of 
 the manner in which the results of experiments may be 
 arranged. 
 
 The first is a statement of the composition of ripe peas. 
 
88 
 
 deduced from experiments made by Einliof ; the second 
 are of the products afforded by oak bark, deduced from 
 experiments conducted by myself. 
 
 Parts. 
 
 3840 parts of ripe peas afford, of starch , 1265 
 Fibrous matter analogous to ^ 
 starch, with the coats ofC 840 
 the peas " " 3 
 
 3840 parts of a substance analogous to gluten 550 
 
 Mucilage . . - - 249 
 Saccharine matter - - 81 
 
 Albumen . . - . 66 
 
 Volatile matter - - - 640 
 Earthy phosphates - - 11 
 
 Loss 229 
 
 1000 parts of dry oak bark, from a small tree depri- 
 ved of epidermis, contain, 
 
 Of woody fibre - - - - 876 
 
 — tannin ----- 57 
 
 — extract - - - - - 31 
 
 — mucilage . - - - 18 
 -— matter rendered insoluble during 1 
 
 evaporation, probably a mixture > 9 
 of albumen and extract t ) 
 
 — loss, partly saline matter - - 30 
 
 To ascertain the primary elements of the different ve- 
 getable principles, and the proportions in which they 
 are combined, different methods of analysis have been 
 adopted. The most simple are their decomposition by 
 heat, or their formation into new products by combus- 
 tion. 
 
 When any vegetable principle is acted on by a strong 
 red heat, its elements become newly arranged. Such 
 of them as are volatile are expelled in the gaseous form ; 
 and are either condensed as fluids, or remain permanent- 
 ly elastic. The fixed remainder is either carbonaceous, 
 earthy, saline, alkaline, or metallic matter. 
 
 To make correct experiments on the decomposition of 
 vegetable substances by heat, requires a complicated ap- 
 
89 
 
 paratus, much time and labour, and all the resources 
 of the philosophical chemist : but such results as are 
 useful to the agriculturist may be easily obtained. The 
 apparatus necessary is a green glass retort, attached by 
 cement to a receiver, connected with a tube passing un- 
 der an inverted jar of known capacity, filled with wa- 
 ter.* A given weight of the substauce is to be heated 
 to redness in the retort over a charcoal fire ; the receiver 
 is to be kept cool, and the process continued as loug as 
 any elastic matter is generated. The condensible fluids 
 will collect in the receiver, and the fixed residuum will 
 be found in the retort. The fluid products of the dis- 
 tillation of vegetable substances are principally water, 
 with some acetous and mucous acids, and empyreumatic 
 oil, or tar, and in some cases ammonia. The gases are 
 carbonic acid gas, carbonic oxide, and carburetted hy- 
 drogene ; sometimes with olefiant gas, and hydrogene ; 
 and sometimes, but more rarely, with azote. Carbonic 
 acid is the only one of those gases rapidly absorbed by 
 water ; the rest are inflammable ; olefiant gas burns witli 
 a bright white light ; carburetted hydrogene with a light 
 like wax ; carbonic oxide Avith a feeble, blue flame. 
 The properties of hydrogene and azote liave been de- 
 scribed in the last lecture. The specific gravity of 
 carbonic acid gas, is to that of air as 20.7 to 13.7, and 
 it consists of one proportion of carbon 11.4, and two 
 of oxygene 30. • The specific gravity of gaseous oxide 
 of carbon, is taking the same standard 13.2, and it con- 
 sists of one proportion of carbon, and one of oxygene. 
 
 The specific gravities of carburetted liydrogene and 
 olefiant gas are respectively eight and thirteen ; both 
 contain four proportions of hydrogene ; the first contains 
 one proportion, the second two proportions of carbon. 
 
 If the weight of the carbonaceous residuum be added 
 to the weight of the fluids condensed in the receiver, 
 and they be subtracted from the whole weight of the 
 substance, the remainder will be the weight of the gas- 
 eous matter. 
 
 The aceous and mucous acids, and the ammonia form- 
 ed are usually in very small quantities ; and by com- 
 
 * See Fig. 1 4. 
 M 
 
90 
 
 jiariiii; the proportions^ of water and charcoal with the 
 quantity of the i:;as!ies, takini; into account their qualities, . 
 a a;eneral idea may be formed of the^ composition of the 
 substance. The [iroportions of tlie elements in the 
 e;rcater number of tlie vegetable substances which can 
 be used as food, have been already ascertained by phi- 
 losophical chemists, and have been stated in the preced- 
 ing pjiges ; the analysis by distillation may, however, 
 iu some cases, be useful in estinuiting the pow ers of ma- 
 nures, in a manner that will be explained in a future 
 lecture. 
 
 The statements of the composition of vegetable sub- 
 stances, quoted from M. M. Gay Lussac and Thenard, 
 were obtained by these philosophers by exposing the 
 sul)stances to the action of heated hyper-oxymuriate of 
 potassa; a body that consists of potassium, chlorine,' 
 and oxygene; and which aflbrded oxygene to the carbon 
 and the hydrogene. Their experiments were made in 
 a peculiar apparatus, and required great caution, and 
 were of a a ery delicate nature. It will not therefore 
 be necessary to enter upon any details of them. 
 
 It is evident from the whole tenor of the statements 
 which have been made, and the most essential vegeta- 
 ble substances consist of hydrogene, carbon, and oxy- 
 gene in difterent proportions, generally alone, but in 
 some few^ cases combined with azote. The acids, al- 
 kalies, earths, metallic oxides, and saline compounds, 
 though necessary in the vegetable cecouomy, must be 
 considered as of less importance, particularly in their 
 relation to agriculture, tlian the other principles : and as 
 it appears from M. de Saussure's table, and from other 
 experiments, they differ in the same species of vegeta- 
 ble when it is raised on different soils. 
 
 M. M. Gay Lussac and Thenard have deduced three 
 propositions, which they have called lairs from their ex- 
 periments on vegetable substances. The Jirst is, ^'that 
 a vegetable substance is always acid w henever the oxy- 
 gene it contains is to the hydrogene in a greater pro- 
 portion than in w ater.'" 
 
 The second. •• that a vegetable substance is always 
 resinous or oily or spiritous whenever it contains oxy- 
 gene in a smaller proportion to the hydrogene than exists 
 iu ^va(cr.*^ 
 
91 
 
 The third, " that a ve2;etable substance is neitlier acid 
 nor resinous ; but is either saccharine or mucilaginous, 
 or analogous to woocly fibre or starcli, whenever the 
 oxygene and hydrogene in it are in the same proportions 
 as in water. 
 
 New experiments upon other vegetable substances, 
 besides those examined by M. M. Gay Lussac and 
 Thenard, are required before these interesting conclu- 
 sions can be fully admitted. Their researches establish, 
 however, the. close analogy between several vegetable 
 compounds differing in their sensible qualities, and com- 
 bined with those of other chemists, offer simple expla- 
 nations of several processes in nature and art, by which 
 different vegetable substances are converted into each 
 other, or changed into new compounds. 
 
 Gum and sugar afford nearly the same elements by 
 analysis ; and starch differs from them only in contain- 
 ing a little more carbon. The peculiar properties of 
 gum and sugar must depend chiefly upon the different ar- 
 rangement, or degree of condensation of their elements ; 
 and it would be natural to conceive from the composi- 
 tion of these bodies, as well as that of starch, that all 
 three would be easily convertible one into the other ; 
 which is actually the case. 
 
 At the time of the ripening of corn, the saccharine 
 matter in the grain, and that carried from the sap ves- 
 sels into the grain, becomes coagulated, and forms starch. 
 And in the process of malting, the converse change oc- 
 curs. The starch of grain is converted into sugar. As 
 there is a little absorption of oxygene, and a formation 
 of carbonic acid in this case, it is probal)le that the 
 starch loses a little carbon, which combines with the 
 oxygene to form carbonic acid ; and probably the oxy- 
 gene tends to acidify the gluten of the grain, and thus 
 breaks down the texture of the starch ; gives a new ar- 
 rangement to its elements, and renders it soluble in wa- 
 ter. 
 
 Mr. Cruikshank, by exposing syrup to a substance 
 named phosphuret of lime, which has a great tendency 
 to decompose water, converted a part of the sugar into 
 a matter analogous to mucilage. And M. Kirchoff, re- 
 cently, has converted starch into sugar by a very sim- 
 
92 
 
 |>le pi'(Ke;?s, iliat of boiling in very diluted suipliiu'i( 
 acid. The proportions are 100 parts of starclj, 400 
 parts of water, and 1 part of sulphuric acid by weiglrt. 
 This mixture is to be kept boiling for 40 hours ; the loss 
 of water by evaporation being supplied by new cpianti- 
 ties. The acid is to be neutrallized by lime ; and the 
 sugar crystallized by cooling. This experiment has 
 been tried with success by many persons. Dr. Tuthili, 
 from a pound and a half of potato starch, procured a 
 pound and a quarter of crystalline, brown^sugar ; which 
 he conceives possesses properties intermediate between 
 cane sugar and grape sugar. 
 
 It is probable that the conversion of starch into sugar 
 is effected merely by the attraction of the acid for the 
 elements of sugar ; for various experiments have been 
 made, which prove that the acid is not decomposed, and 
 that no elastic matter is set free : probably the colour of 
 the sugar is owing to the disengagement, or new combi- 
 nation of a little carbon, the slight excess of which, as 
 has been just stated, constitutes the only difference per- 
 ceptible by analysis between sugar and starch. 
 
 M. Bouillon la Grange, by slightly roasting starch, 
 has rendered it soluble in cold water ; and the solution 
 evaporated afforded a substance, having the characters 
 of mucilage. 
 
 Gluten and albumen differ from the other vegetable 
 products, principally by containing azote. When glu- 
 ten is kept long in water it undergoes fermentation; am- 
 monia, (which contains its azote) is given off with ace- 
 tic acid : and a fatty matter and a substance analogous 
 to woody fibre remain. 
 
 Extract, tannin, and gallic acid, when their solutions 
 are long exposed to air, deposit a matter similar to woody 
 fibre ; and the solid substances are rendered analogous 
 to woody fibre by slight roasting ; and in tliese cases it 
 is probable that part of their oxygene and hydrogene is 
 separated as water. 
 
 All the other vegetable principles differ from the ve- 
 getable acids in containing more hydrogene and carbon, 
 or less oxygene ; many of them therefore are easily con- 
 verted into vegetable acids by a mere subtraction of some 
 proportions of hydrogene. The vegetable acids, for the 
 
9a 
 
 most part, are convertible into each otlier by easy pro- 
 cesses. The oxalic contains most oxygene ; the acetic 
 the least: and this last substance is easily formed by the 
 distillation of other vegetable substances, or by the ac- 
 tion of the atmosphere on such of them as are soluble in 
 water ; probably by the mere combination of oxygene 
 with hydrogene and carbon, or in some cases by the sub- 
 traction of a portion of hydrogene. 
 
 Alcohol, or spirits of uine, has been often mentioned 
 in the course of these Lectures. This substance was 
 not describe'd amongst the vegetable principles, because 
 it has never been found ready formed in the organs of 
 plants. It is procured by a change in the principles of 
 saccharine matter, in a process called vinous fermenta- 
 tion. 
 
 The expressed juice of the grape contains sugar mu- 
 cilage, gluten, and some saline matter, principally com- 
 posed of tartaric acid: when this juice, or must, as it is 
 commonly called, is exposed to the temperature of about 
 70®, the fermentation begins : it becomes thick and tur- 
 bid ; its temperature increases, and carbonic acid gas is 
 disengaged iii abundance. In a few days the fermenta- 
 tion ceases ; the solid matter that rendered the juice tur- 
 bid falls to the bottom, and it clears ; the sweet taste of 
 the fluid is in great measure destroyed, and it is become 
 spirituous. 
 
 Fabroui has shewn that the gluten in must is essen- 
 tial to fermentation ; and that chemist has made saccha- 
 rine matter ferment, by a<lding to its solution in water, 
 common vegetable gluten and tartaric acid. Gay Lus- 
 sac has demonstrated that must will not ferment when 
 freed from air by boiling, and placed out of tiie contact 
 of oxygene ; but that fermentation begins as soon as it 
 is exposed to the oxygene of air, a litth^ of that princi- 
 ple being absorbed; and ihat it then continues indepen- 
 dent of the presence of the atmosphere. 
 
 In the manufacture of ale and porter, the sugar form- 
 ed during the germination of barley is made to ferment 
 by dissolviug it in water with a little yeast, which con- 
 tains gluten in the state proper for producing fermenta- 
 tion, and exposing it to the requisite temperature ; car- 
 bonic acid ;;as is given off as in the fermentation of must, 
 and the liquor gradually becomes spirituous. 
 
94 
 
 Similar plisenomena occur in the fermentation of the 
 sugar in the juice of apples and other ripe fruits. It* 
 appears that fermentation depends entirely upon a new 
 arrangement of the elements of sugar ; part of the car- 
 bon uniting to oxygene to form a carbonic acid, and the 
 remaining carbon, hydrogene, and oxygene combining 
 as alcohol ; and the use of the gluten or yeast, and the 
 primary exposure to air seems to be to occasion the for- 
 mation of a certain quantity of carbonic acid ; and this 
 change being once produced is continued ; its agency 
 may be compared to t)iat of a spark in producing the in- 
 flammation of gunpowder ; the increase of temperature 
 occasioned by tlie formation of one quantity of carbonic 
 acid occasions tlie combination of the elements of another 
 quantity. 
 
 The results obtained by different chemists in experi- 
 ments on the analysis of alcohol differ so much, that no 
 general conclusions can be drawn from them. If it be 
 supposed that one proportion of carbonic acid is form- 
 ed in the fermentation of sugar, then, according to Dr. 
 Thomson's analysis of sugar, which gives its composi- 
 tion as 3 proportions of carbon, 4 of oxygene, and 8 of 
 liydrogene, alcohol would consist of 2 proportions of 
 carbon, 2 of oxygene, and 8 of hydrogene ; and it might 
 be considered as containing the same elements as two 
 proportions of olefiant gas, with tw o proportions of oxy- 
 gene. 
 
 Alcohol in its purest known form, is a highly inflam- 
 mable liquid, of specific gravity 796, at the temperature 
 of 60« ; it boils at about 170^ Fahrenheit. This alco- 
 hol is obtained by repeated distillation of the strongest 
 common spirit from the salt called by chemists muriate 
 of lime, it having been previously heated red hot. 
 
 The strongest alcohol obtained by the distillation of 
 spirits without salts, has seldom a less specific gravity 
 than 825 at 60° ; and it contains, according to Lowitz's 
 experiments, 89 parts of the alcohol of 796, and 11 parts 
 of water. The spirit established as 'proof spirit by act 
 of parliament passed in 1762, ought to have the specific 
 gravity of 916 ; and this contains nearly equal weights 
 of pure alcohol and water. 
 
 The alcohol in fermented liquors is in combination 
 
95 
 
 with M'aier, colouring matter, sugar, mucilage, and the 
 vegetable acids. It has been often doubted whether it 
 can be procured by any other process than distillation ; 
 and some persons have even supposed that it is formed 
 by distillation. The recent experiments of Mr. Brande 
 are conclusive against both these opinions. That gentle- 
 man has shewn that the colouring and acid matter in 
 wines may be, for the most part, separated in a solid 
 form by the action of a solution of sugar of lead (ace- 
 tate of lead,) and that the alcohol may be then obtained 
 by abstracting the water by means of hydrate of potas- 
 sa or muriate of lime, without artiiicial heat. 
 
 The intoxicating powers of fermented liquors depend 
 on the alcohol that they contain ; but their action on the 
 stomach is modified by the acid, saccharine, or mucila- 
 ginous substances they hold in solution. Alcohol pro- 
 bably acts with most eificacy when it is most loosely 
 combined ; and its energy seems to be impaired by union 
 with large quantities of water, or with sugar or acid, or 
 extractive matter. 
 
 The following table contains the results of Mr. 
 Brande's experiments on the quantity of alcohol of 825 
 at 60°, in different fermented liquors. 
 
96 
 
 WINJE. 
 
 Port - - - - 
 
 21,40 
 
 Ditto - - . 
 
 22,30 
 
 Ditto - . - - 
 
 23,39 
 
 Ditto - - - 
 
 23,71 
 
 Ditto - . . - 
 
 24,29 
 
 Ditto - > - 
 
 35,83 
 
 Madeira - - - 
 
 19,34 
 
 Ditto - - - 
 
 21,40 
 
 Ditto . - - . 
 
 23,93 
 
 Ditto - - - 
 
 24,42 
 
 Sherry - - . 
 
 18,25- 
 
 Ditto - - - 
 
 18,79 
 
 Ditto - - . - 
 
 19,81 
 
 Ditto - - - 
 
 19,83 
 
 Claret - . - - 
 
 12,91 
 
 Ditto - - - 
 
 14,03 
 
 Ditto - - - - 
 
 16,32 
 
 Calcavella - - 
 
 18,10 
 
 Lisbon - - - 
 
 18,94 
 
 Mala.^a - - - 
 
 17,2G 
 
 Bucellas - - - 
 
 18.49 
 
 Red Madeira - 
 
 18,40 
 
 Malmsey Madeira 
 
 1G,40 
 
 Marsala - - - 
 
 25,87 
 
 Ditto - - - 
 
 17,26 
 
 Red Champas^nc 
 
 11,30 
 
 White Champagne 
 
 12,80 
 
 Bnrginidy - - 
 
 14,53 
 
 Ditto - - - 
 
 11,95 
 
 WINE. 
 
 White Hermitage 
 Red Hermitage 
 Hock - - - - 
 Ditto - - - 
 Vin de Grave 
 Frontignac - - 
 Coti Roti - - - 
 Rousillon - - 
 Cape Madeira - 
 Cape Miischat - 
 Constantia - - 
 Tent - - . - 
 Sheraaz - - - 
 Syracuse - - 
 >Jice - . - - 
 Tokay - - - 
 Raisin Wine - - 
 drape Wine 
 Currant Wine - 
 Gooseberry Wine 
 Elder Wine 
 Cider - - - - 
 Perry _ - - 
 Bro\A'n Stout - - 
 Ale .... 
 Bi'andy - - - 
 Rum . . - - 
 Hollands - - . 
 
 1 
 
 
 17,43 
 
 12,32 
 
 14,37 
 
 8,88 
 
 12,80 
 
 12,79 
 
 12,32 
 
 17,26 
 
 IS, 11 
 
 18,25 
 
 19,75 
 
 13,30 
 
 15,52 
 
 15,28 
 
 14,63 
 
 9,88 
 
 25,77 
 
 18,11 
 
 20,55 
 
 11,84 
 
 9,87 
 
 9,87 
 
 9,87 
 
 6,80 
 
 8,88 
 
 53,39 
 
 53,68 
 
 51,60 
 
 wmmmMmmiBm 
 
97 
 
 The spirits distilled from diflfereiit fermented liquors 
 differ in their flavour : for peculiar odorous matter, or 
 volatile oils, rise in most cases with the alcohol. The 
 spirit from malt usually has an cmpyreumatic taste like 
 that of oil, formed by the distillation of vegetable sub- 
 stances. The best brandies seem to owe their flavour 
 to a peculiar oily matter, formed probably by the action 
 of the tartaric acid on alcohol; and rum derives its char- 
 acteristic taste from a principle in the sugar cane. All 
 the common spirits may, I find, be deprived of their pe- 
 culiar flavour by repeatedly digesting them with a mix- 
 ture of well burnt charcoal and quicklime ; they then af- 
 ford pure alcohol by distillation. The cogniac brandies, 
 I find, contain vegetable prussic acid, and their flavour 
 may be imitated by adding to a solution of alcohol in 
 water of the same strength, a few drops of the ethereal 
 oil of wine produced during the formation of ether,* and 
 a similar quantity of vegetable prussic acid procured 
 from laurel leaves or any bitter kernels. 
 
 I have mentioned ether in the course of this Lecture ; 
 this substance is procured from alcohol by distilling a 
 mixture of equal parts of alcohol and sulphuric acid. It 
 is the lightest known liquid substance, being of a spe- 
 cific gravity 632 at 60^. It is very volatile, and rises 
 in vapour even by the heat of the body. It is highly in- 
 flammable. In the formation of ether it is most proba- 
 ble that carbon and the elements of water are separated 
 from the alcohol, and that ether differs from alcohol in 
 containing less oxygene and carbon ; but its composi- 
 tion has not yet been accurately ascertained. Like al- 
 cohol it possesses intoxicating powers. 
 
 A number of the changes taking place in the vegeta- 
 ble principles depend upon the separation of oxygene 
 and hydrogene as Avater from the compound ; but there 
 is one of very great importance, in wliich a new combi- 
 nation of the elements of water is the principal opera- 
 tion. This is in the manufacture of bread. When any 
 kind of flour, which consists principally of starch, is 
 
 * In the process of tlie distillation of ulcoliol and sulphuric acid af- 
 ter tlie ether is procured ; by a higher degree of heat, a yellow fluid 
 is produced, whicli is the substance in question. It has a f, agrant 
 smell and an agreeable ta-ite, / 
 
 N I 
 
made into a paste with water, and immediately and gra- 
 dually Iieated to about 440°, it increases in weight, and 
 is found entirely altered in its properties ; it has lost its 
 solubility in water, and its power of being converted 
 into sugar. In ibis state it is unleavened bread. 
 
 A\ hen the Hour of corn or the starch of potatoes, mix- 
 ed with boiled })otaioes, is made into a paste with water, 
 kept warm, aiul suU'ered to remain 30 or 40 hours, it 
 ferments, carbonic acid gas is .disengaged from it, and 
 it becomes filled with globules of elastic iluid. In this 
 state it is raised dough, and aflbrds by baking, leavened 
 bread ; but this bread is sour and disagreeable to the 
 taste ; and leavened bread for use is made by mixing a 
 little dough, that lias fermented, Avith new dougli, and 
 kneading them together, or by kneading the bread with 
 a small quantity of yeast. 
 
 In the formation of wheaten bread more than^. of the 
 elements of water combine with the flour ; more water is 
 consolidated in the formation of bread from barley, and 
 still more in that from oats; but the gluten in wheat, be- 
 ing in much larger quantity than in otlier grain, seems 
 to form a combination with the starch and water, which 
 renders wheaten bread more digestible than the other 
 species of bread. 
 
 The arrangement of many of the vegetable principles 
 in the diil'erent parts of plants has been incidentally 
 mentioned in this Lecture ; but a more particular state- 
 ment is required to allbrd just views of the relation be- 
 tween their organization and chemical consritution, which 
 is an o])ject of great importance. The tubes and hex- 
 agonal cells in the vascular system of plants are compo- 
 sed of woody fibre ; and when they are not filled with 
 fluid matter they contain some of the solid materials 
 whi( h formed a constituent part of the fluids belonging 
 to them. 
 
 In the roots, trunk, and branches, the bark, albur- 
 num, and heartwood, the leaves and flowers ; the great 
 basis of the solid parts is woody fibre. It forms by far 
 the greatest part of the heartwood and bark ; there is 
 less in the alburnum, and still less in the leaves and 
 flowers. The alburnum of the birch contains so much 
 sui;ar and mucilage, that it is sometimes used in the 
 
y9 
 
 North of Europe as a substitute lor bread. The leaves 
 of the cabbage, broccoli, and seacale, contain much mu- 
 cilage, a little saccharine matter, and a little albumen. 
 
 From 1000 parts of the leaves of common cabbage I 
 obtained 41 parts of mucilage, 24 of sugar, and 8 of al- 
 buminous matter. 
 
 In bulbous roots, and sometimes in common roots, a 
 large quantity of starch, albumen, and mucilage, are 
 often found deposited in the vessels ; and they are most 
 abundant after the sap has ceased to flow ; and aftbrd a 
 nourishment for the early shoots made in spring. The 
 potato is the bulb that contains the largest quantity of 
 soluble matter in its cells and vessels ; and it is of most 
 importance in its application as food. Potatoes in ge- 
 neral afford from one-fifth to one-seventh their weight 
 of dry starch. From 100 parts of the common Kidneij 
 potato, Dr. Pearson obtained from 32 to 28 parts of meal, 
 which contained from 23 to 20 of starch and mucilage : 
 and 100 parts of the Apple potato in various experiments, 
 afford me from 18 to 20 parts of pure starch. From five 
 pounds of the variety of the potato called Captain hart, 
 Mr. Skrimshire, jun. obtained 12 oz. of starch, from the 
 same quantity of the Hough red potato 10| oz., from the 
 Moulton white 111, from the Yorkshire kidney 10| oz. 
 from Hundred eyes 9 oz., from Purple red 8j, from Ox 
 nolle 8j.. The other soluble substances in the potato 
 are albumen and mucilage. 
 
 From the analysis of Einhoff it appears that 7680 
 parts of potatoes afford 
 
 Of Starch 1153 
 
 — Fibrous matter analogous to starch 640 
 
 — Albumen - - - - 107 
 
 — Mucilage in the state of a satura- , ^.^ 
 ted solution ... 
 
 2112 
 
 So that a fourth part of the weight of the potato at least 
 may be considered as nutritive matter. 
 
 The turnip, carrot, and parsnip, afford principally 
 saccharine, mucilaginous, and extractive matter. I ob- 
 tained from 1000 parts of common turnips seven parts 
 
lOU 
 
 of rtiucilai^c, 34 of saccharine mattev, and nearly one 
 part of albumen. 1000 parts of carrots furnished 95 
 parts of sugar, three parts of nnicilage, and one-half of 
 extract; 1000 parts of parsnip aiforded 90 parts of sac- 
 charine matter, and nine parts of mucilage. The Wal- 
 cheran or ichite carrot, gave in 1000 parts, 98 parts of 
 sugar, two parts of mncilage, and one of extract. 
 
 Fruits, in the organization of their soft parts, approach 
 to the nature of bulbs. They contain a certain quanti- 
 ty of nourishment laid up in their cells for the use of 
 the embryon plant ; mncilage, sugar, starch, are found 
 in many of them often combined with vegetable acids. 
 Most of the fruit trees common in Britain have been na- 
 turalized on account of the saccharine matter they con- 
 tain, which, united to the vegetable acids and mucilage, 
 renders tliem at once agreeable to the taste and nutri- 
 tive. 
 
 The value of fruits for the manufacture of fermented 
 liquors may be judged of from the specific gravity of their 
 expressed juices. The best cider and perry are made 
 from those apples and pears that afford the densest juices; 
 and a comparison between different fruits may be made 
 Avith tolerable accuracy by plunging them together into 
 a saturated solution of salt, or a strong solution of sugar : 
 those that sink deepest will afford the richest juice. 
 
 Starch or coagulated mucilage forms the greatest part 
 of the seeds and grains used for food ; and they are ge- 
 nerally combined with gluten, oil, or albuminous mat- 
 ter. In corn, with gluten, in peas and beans, with al- 
 buminous matter; and in rape-seed, hemp-seed, linseed, 
 and the kernels of most nuts with oils. 
 
 I found 100 parts of good full grained wheat sown in 
 autumn to afford 
 
 Of starch - - 77 
 
 — Gluten - - 19 
 100 parts of wheat sown in spring, 
 
 Of starch - - 70 
 
 — Gluten - - 24 
 100 parts of Barbary wheat. 
 
 Of starch - - 74 
 
 — Gluten - - 23 
 100 parts of Sicilian wheat, 
 
101 
 
 Of starch - - 75 
 — Gluten - - 21 
 
 1 have examined dijQTerent specimens of North Ameri- 
 can wheat, all of them have contained rather more glu- 
 ten than the British. In general the wheat of warm cli- 
 mates abounds more in gluten, and in insoluble parts ; 
 and it is of greater specific gravity, harder, and more 
 difficult to grind. 
 
 The wheat of the south of Europe, in consequence of 
 the larger quantity of gluten it contains, is peculiarly fit- 
 ted for making macaroni, and other preparations of flow- 
 er in which a glutinous quality is considered as an ex- 
 cellence. 
 
 In some experiments made on barley, I obtained from 
 100 parts of full and fair Norfolk barley, 
 
 Of Starch - - - 79 
 
 — Gluten - - - 6 
 -—Husk , - . 8 
 
 The remaining seven parts saccharine matter. The su- 
 gar in barley is probably the chief cause why it is more 
 proper for malting than any other species of grain. 
 
 Einhoff has published a minute analysis of barley 
 meal. He found in 3840 parts, 
 
 Of volatile matter - - 360 
 
 — Albumen - - . 44 
 
 — Saccharine matter - 200 
 
 — Mucilage - - - 176 
 
 — Phosphate of lime, with some 
 
 albumen - - . 9 
 
 — Gluten - - - 135 
 
 — Husk, with some gluten and 
 
 starch - - - 260 
 
 — Starch not quite free from 
 
 gluten - - - 2580 
 
 — Loss - - - - 78 
 
 llye afforded to Einhoff, in 3840 parts ; 2520 meal, 
 930 husk, and 390 moisture ; and the same quantity of 
 meal analyzed gave, 
 
102 
 
 Of starch 
 
 - 2345 
 
 — Albumen 
 
 126 
 
 — Mucilage 
 
 436 
 
 — Saccharine matter 
 
 126 
 
 — Gluten not dried 
 
 364 
 
 Remainder husk and loss. 
 
 
 I obtained from 1000 parts of rye, grown in Suifolk^ 
 61 parts of starch, and five parts of gluten, 
 
 100 parts of oats, from Sussex, afibrded me 59 parts 
 of starch, six of gluten and two of saccharine matter. 
 
 1000 parts of peas, grown in Norfolk, afforded me 
 501 parts of starch, 22 parts of saccharine matter, 35 
 parts of albuminous matter, and 16 parts of extract, 
 which become insoluble during evaporation of the sac- 
 charine fluid. 
 
 From 3840 parts of marsh beans (Vicia faba,) Ein- 
 hoff obtained, 
 
 Of Starch ... - 1312 
 
 — Albumen - - - - 31 
 
 — Other matters which may be"] 
 conceived nutritive; such as ! 49^4 
 gummy, starchy, fibrous mat- j 
 
 ter analogous to animal matter J 
 
 The same quantity of kidney beans (Phaseolus vul- 
 garis y) afforded, 
 
 Of matter analagous to starch - 1805 . 
 
 — Albumen and matter ap- ') 
 
 proaching to animal mat- V 851 
 
 ter in its nature - ) 
 
 — Mucilage - - - 799 
 
 From 3840 parts of lentiles he obtained 1260 parts 
 of starcli, and 1433 of a matter analogous to animal mat- 
 ter. 
 
 The matter analogous to animal matter is described 
 by Einhoff ; as a glutinous substance insoluble in wa- 
 ter ; soluble in alcohol when dry, having the appearance 
 of glue ; probably a peculiar modification of gluten. 
 
103 
 
 From 16 parts of hemp-seeds Biicholz obtained three 
 parts of oil, three and a half parts of albumen, about 
 one and three quarters of saccharine and gummy matter. 
 The insoluble husks and coats of the seeds weighed six 
 and one-eighth parts. 
 
 The different parts of flowers contain different sub- 
 stances : the pollen, or impregnating dust of the date, 
 has been found by Fourcroy and Vauquelin to contain 
 a matter analogous to gluten, and a soluble extract 
 abounding in malic acid. Link found in the pollen of 
 the hazel-tree, much tannin and gluten. 
 
 Saccharine matter is found in the nectarium of flow- 
 ers, or the receptacles within the corolla, and by tempt- 
 ing the larger insects into the flowers, it renders the work 
 of impregnation more secure; for the pollen is often by 
 their means applied to the stigma ; and this is particu- 
 larly the case when the male and female organs are in 
 different flowers or different plants. 
 
 It has been stated that the fragrance of flowers de- 
 pends upon the volatile oils they contain ; and these oils, 
 by their constant evaporation, surround the flower with 
 a kind of odorous atmosphere ; which, at the same time 
 that it entices larger insects, may probably preserve the 
 parts of fructification from the ravages of smaller ones. 
 Volatile oils, or odorous substances, seem particularly 
 destructive to these minute insects and animalcules 
 which feed on the substance of vegetables ; thousands 
 of aphides may be usually seen in the stalk and leaves 
 of the rose but none of them are ever observed in the 
 flower. Camphor is used to preserve the collections of 
 naturalists. The woods that contain aromatic oils are 
 remarked for their indestructibility ; and for their ex- 
 emption from the attacks of insects : this is particularly 
 the case with the cedar, rose- wood, and cypress. The 
 gates of Constantinople, which were made of this last 
 wood, stood entire from the time of Constantine, their 
 founder, to that of Pope Eugene IV. a period of 1100 
 years. 
 
 The petals of many flowers afford saccharine and 
 mucilaginous matter. The white lily yields mucilage 
 abundantly : and the orange lily a mixture of mucilage 
 and sugar ; the. petals of the convolvulus afford sugar^, 
 mucilage, and albuminous matter. 
 
104 
 
 The chemical nature of the colouring matters of flow- 
 ers has not as yet been subject to any very accurate ob- 
 servation. These colouring matters, in general, are very 
 transient, particularly the blues and reds ; alkalies 
 change the colours of most flowers to green, and acids 
 to red. An imitation of the colouring matter may be 
 made by digesting solutions of gall-nuts with chalk : 
 a green fluid is obtained, which becomes red by the ac- 
 tion of an acid ; and has its green colour restored by 
 means of alkalies. 
 
 The yellow colouring matters of flowers are the most 
 permanent ; the carthamus contains a red and a yellow 
 colouring matter ; the yellow colouring matter is easily 
 dissolved by water, and from the red, rouge is prepared 
 by a process which is kept secret. 
 
 The same substances as exist in the solid parts of 
 plants are found in their fluids, with the exception of 
 Avoody fibre. Fixed and volatile oils containing resin 
 or camphor, or analogous substances in solution exist 
 in the cylindrical tubes belonging to a number of plants. 
 Different species of Euphorbia emit a milky juice, which 
 when exposed to air deposit a substance analogous to 
 starch, and another similar to gluten. 
 
 Opium, gum elastic, gamboge, the poisons of the Upas 
 Antiar and Tiiite, and other substances that exude from 
 plants, may be considered as peculiar juices belonging 
 to appropriate vessels. 
 
 The sap of plants, in general, is very compound in 
 its nature : and contains most saccharine, mucilaginous, 
 and albuminous matter in tlie alburnum ; and most tan- 
 nin and extract in the bark. The cambium, which is 
 the mucilaginous fluid found in trees between the wood 
 and the bark, and which is essential to the formation of 
 new parts, seems to be derived from these two kinds of 
 sap ; and probably is a combination of the mucilaginous 
 and albuminous matter of one, with the astringent mat- 
 ter of the other, in a state fitted to become organized by 
 the separation of its watery parts. 
 
 The alburnous saps of some trees have been chemi- 
 cally examined by Vauquelin. He found in those of tlie 
 elm, beech, yoke elm, hornbeam and birch, extractive 
 and mucilaginous matter, acetic acid combined with po- 
 tassa or lime. The solid matter afforded by their cva- 
 
105 
 
 poratiou yielded an ammouiacal smell, probably owing 
 to albumen : the sap of the birch afforded saccharine 
 matter. 
 
 Deyeux in the sap of the vine and the yoke elm has 
 detected a matter analogous to the curd of milk. 1 found 
 a substance similar to albumen in the sap of the walnut 
 tree. 
 
 I found the juice which exudes from the vessels of 
 the marshmallow when cut, to be a solution of mucilage. 
 - The fluids contained in the sap vessels of wheat and 
 barley, afforded in some experiments which I made on 
 them, mucilage, sugar, and a matter which coagulated 
 by heat ; which last was most abundant in wheat. 
 
 The following table contains a statement of the quan- 
 tity of soluble or nutritive matters contained in varieties 
 of the different substances tliat have been mentioned, 
 and of some others which are used as articles of food, 
 either for man or cattle. The analyses are my own ; 
 and were conducted with a view to a knowledge of the 
 general nature and quantity of the products, and not of 
 their intimate chemical composition. The soluble mat- 
 ters afforded by the grasses, except that from the florin 
 in winter, were obtained by Mr. Sinclair, gardener to 
 the Duke of Bedford, from given weights of the grasses 
 cut when the seeds were ripe ; they were sent to me by 
 his Grace's desire for chemical examination ; and form 
 part of the results of an important and extensive series 
 of experiments on grasses, made by direction of the 
 Duke, at Woburn Abbey, the full details of which I 
 shall hereafter have the pleasure of stating. 
 
 o 
 
106 
 Table of the Quantities of sohtble or nutritive Mat- 
 ters afforded by 1000 Parts of different vegetable 
 Substances, 
 
 Vegetables or vegeta- 
 ble Subhtajice. 
 
 Middlesex wheat, 
 
 average crop - • 
 
 Spring wheat - - - - . 
 
 Milde\vedwheatofl806 
 
 Blighted wlieat of 1804 
 
 Thick-skinned Sicili- > 
 
 an wheat of 1810 3 
 
 Thin-skinned Sicili-'? 
 
 an wheat of ISIO 5 
 
 Wheat from Poland - - 
 
 North American wheat 
 
 Norfolk barley 
 
 Oats from Scotland - - 
 Rje from Yorkshire - - 
 
 Common bean 
 
 Dry peas --.---..- 
 
 Potatoes - 
 
 Linseed cake ...... 
 
 Red Beet 
 
 White Beet 
 
 Parsnip 
 
 Carrots 
 
 Common turnips - . - . 
 Swedish turnips - - - - 
 
 Cabbage 
 
 Broad-leaved clover - - 
 Long-rooted clover - - 
 
 \Miite clover 
 
 Sainfoin 
 
 Lucerne -.--.-... 
 Meadow fox-tail grass 
 Perennial rye-grass - - 
 Fertile meadow grass 
 Kougliish mtadow grass 
 Crested dog's-tail grass 
 Spiked fescue grass • 
 Sweet-scented soft, do. 
 Do. do. vernal, do 
 
 Fiorin -- 
 
 Fiorin cut in winter - - 
 
 a> c 2; 
 
 955 
 
 940 
 210 
 650 
 
 955 
 
 961 
 
 950 
 
 955 
 
 920 
 
 743 
 
 792 
 
 570 
 
 574 
 
 :fr. 260 
 
 ' to 200 
 
 151 
 
 148 
 
 136 
 
 99 
 
 98 
 
 42 
 
 64 
 
 73 
 
 39 
 
 39 
 
 32 
 
 39 
 
 23 
 
 33 
 
 39 
 
 78 
 
 39 
 
 35 
 
 19 
 
 82 
 
 50 
 
 54 
 
 76 
 
 765 
 
 700 
 178 
 
 520 
 
 725 
 
 722 
 
 750 
 730 
 790 
 641 
 645 
 426 
 501 
 :fr. 200 
 to 155 
 123 
 
 14 
 
 13 
 9 
 3 
 7 
 9 
 
 41 
 
 31 
 
 30 
 
 29 
 
 28 
 
 18 
 
 24 
 
 26 
 
 65 
 
 29 
 
 28 
 
 15 
 
 72 
 
 43 
 
 46 
 
 64 
 
 70 
 15 
 38 
 
 22 
 
 :fr. 20 
 
 'to 15 
 
 11 
 
 121 
 
 119 
 
 90 
 
 95 
 
 34 
 
 51 
 
 24 
 
 3 
 
 4 
 
 1 
 
 2 
 
 1 
 
 o 
 4 
 6 
 5 
 o 
 
 2 
 4 
 4 
 5 
 8 
 
 3 - 
 
 190 
 
 240 
 
 32 
 
 130 
 
 230 
 
 200 
 
 225 
 
 60 
 
 87 
 
 109 
 
 103 
 
 35 
 
 :fr. 40 
 
 'to 30 
 
 17 
 
 14 
 
 4 
 
107 
 
 All these substances \yere submitted to experiment 
 green, and in their natural states. It is probable that 
 the excellence of the different articles as food will be 
 found to be in a great measure proportional to the quan- 
 tities of soluble or nutritive matters they afford ; but 
 still these quantities cannot be regarded as absolutely 
 denoting their value. Albuminous or glutinous matters 
 have the characters of animal substances ; sugar is more 
 nourishing, and extractive matter less nourishingj than 
 any other principles composed of carbon, hydrogene, 
 and oxygene. Certain combinations likewise of these 
 substances may be more nutritive than others. 
 
 I have been informed by Sir Joseph Banks, that the 
 Derbyshire miners in winter prefer oatcakes to wheatcn 
 bread; finding that this kind of nourishment enables thera 
 to support their strength and perform their labour bet- 
 ter. In summer, they say oat cake heats them, and they 
 then consume the finest wheaten bread they can procure. 
 Even the skin of the kernel of oats probably has a 
 nourishing power, and is rendered partly soluble in the 
 stomach with the starch and gluten. In most countries 
 of Europe, except Britain, and in Arabia, horses are fed 
 with barley mixed with chopped straw ; and tiie chop- 
 ped straw seems to act the same part as the husk of the 
 oat. In the mill 141bs. of good wheat yield "on an ave- 
 rage ISlbs. of flour; the same quantity of barley 12lbs. 
 and of oats only 81bs. 
 
 In the south of Europe, hard or thin-skinned wheat 
 is in higher estimation, than soft or thick-skinned wheat ; 
 the reason of which is obvious, from the larger quantity 
 of gluten and nutritive matter it contains. I have an 
 analysis of only one specimen of thin-skinned wheat, 
 so that other specimens may possibly contain more nu- 
 tritive matter than that in the Table ; the B.i rhary and 
 Sicilian wheats, before refer; ed to, were thick sk'nned 
 wheats. In England the difficulty of grinding thin- 
 skinned wheat is an objection ; but this difficiiUy is easily 
 overcome by moistening the corn.* 
 
 *For the followinc^ note on the subject I am indebted to the kind- 
 ness of the Right Hon. Sir Joseph Banks, Bart. K. B. 
 
1 08 
 
 injormiiluv.t received from John Jeffrey^ Esq. His Mijestifs 
 Consul General at Lisbon, in Ansxvcr to Queries transmitted to 
 him, from the Comm. of P. C, for Trade, dated Jan. 12, 1812, 
 
 To grind hard corn with the mill stones used in England, the wheat 
 must be well screened, tiien sprinkled with water at the nuller's dis- 
 cretion, and laid in heaps and frequently turned and thoroughly mix- 
 ed, which will soften the husk so as to make it separate from the flour 
 in grinding, and of course give the flour a brighter colour ; other- 
 wise the flinty quality of the wheat, and the thinness of the skin will 
 prevent its separation, and will render the flour unfit for making into 
 bread. 
 
 I am informed by a miller of considerable experience, and who 
 works his mills entirely with the stones from England or Ireland, 
 that he frequently prepares the hard Barbary corn by immersing it 
 in water in close wicker baskets, and spreading it thinly on a floor to 
 dry; much flepends on the judgment and skill of the miller in pre- 
 paring the corn for the mill according to its relative quality. I beg 
 to observe, that it is not from this previous process of wetting the 
 corn that the weight in the flour of hard corn is increased ; but from 
 its natural quality it imbibes considerably more water in making it into 
 bread. The mill-stones must not be cut too deep, but the furrows 
 very fine, and picked in the usual way. The mills should work with 
 less velocity in grinding hard corn than with soft, and set to work at 
 first with soft corn, till the mill ceases to work well; then put on the 
 hard corn. Hard wheat always sells at a higher price in the market 
 than soft wheat, on an average of ten or fifteen per cent. ; as it pro- 
 duces more flour in proportion, and less bran than the soft corn. 
 
 Flour made from hard wheat is more esteemed than what is made 
 from soft corn ; and both sorts are applied to every purpose. 
 
 The flour of hard wheat is in general superior to that made from 
 soft ; and there is no difference in the process of making them into 
 bread; but the flour from hard wheat will imbibe and retain more 
 water in making into bread ; and will consequently produce more 
 weight of bread : it is the practice here, and which I am persuaded 
 it would be advisable to adopt in England, to make bread with flour 
 of hard and soft wheat, which by being mixed, will make the bread 
 much better. 
 
 (Signed) JOHN JEFFERY. 
 
LECTURE IV. 
 
 On Soils : their constituent Parts. On the Analysis of 
 Soils. Of the Uses of the Soil. Of the Rocks and 
 Strata found beneath Soils. Of the Imjjrovement of 
 Soil. 
 
 IS subjects are of more importance to the farmer than 
 the nature and improvement of soils; aiul no parts of 
 the doctrines of agriculture are more capable of being 
 illustrated by chemical inquiries. 
 
 Soils are extremely diversified in appearance and 
 quality ; yet as it was stated in the Introductory Lec- 
 ture, they consist of different proportions of the same 
 elements ; which are in various states of chemical com- 
 bination, or mechanical mixture. 
 
 The substances which constitute soils have been al- 
 ready mentioned. Tliey are certain compounds of the 
 earths, silica, lime, alumina, magnesia, and of the oxides 
 of iron and magnesium ; and animal and vegetable mat- 
 ters in a decomposing state, and saline, acid or alkaline 
 combinations. 
 
 In all chemical experiments on the composition of soils 
 connected with agriculture, the constituent parts obtained 
 are compounds ; and they act as compounds in nature : 
 it is in this state, therefore, that 1 shall describe their 
 characteristic properties. 
 
 1. Silica, or the eartli of ^tw#s, in its pure and crys- 
 tallized form, is the substance known by the name of 
 rock crystal, or Cornish diamond. As it is procured by 
 chemists, it appears in the form of a white impalpable 
 powder. It is not soluble in the common acids, but dis- 
 solves by heat in fixed alkaline lixivia. It is an incom- 
 bustible substance, for it is saturated with oxygene. I 
 have proved it to be a compound of oxygene, and the 
 peculiar combustible body which I have named silicum ; 
 and from the experiments of Berzelius, it is probable 
 that it contains nearly equal weights of these two ele- 
 ments. 
 
jlD 
 
 2. The sensible properties of lime are well known. 
 It exists in soils usually united to carbonic acid ; which 
 is easily disengaged from it by the attraction of the com- 
 mon acids. It is sometimes found combined with the 
 phosphoric and sulphuric acids. Its chemical proper- 
 ties and agencies in its pure state will be described in 
 the Lecture on manures obtained from the mineral king- 
 dom. It is soluble in nitric and muriatic acids, and 
 forms a substance with sulphuric acid, difficult of solu- 
 tion, called gypsum. It is not soluble in alkaline solu- 
 tions. It consists of one proportion 40 of the peculiar 
 metallic substance, which I have named calcium ; and 
 one* proportion 15 of oxygene. 
 
 3. Mumina exists in a pure and crystallized state in 
 the white sapphire, and united to a little oxide of iron 
 and silica in the other oriental gems. , In the state in 
 which it is procured by chemists, it appears as a white 
 powder, soluble in acids and fixed alkaline liquors. 
 iVom my experiments, it appears that alumina consists 
 of one proportion 33 of aluminum, and one 15 of oxy- 
 gene. 
 
 4. Magnesia exists in a pure crystallized state, con- 
 stituting a mineral like talc found in North America. 
 In its common form it is the magnesia usta, or calcined 
 magnesia of druggists. It generally exists in soils com- 
 bined with carbonic acid. It is soluble in all the mi- 
 neral acids ; but not in alkaline lixivia. It is distinguish- 
 ed from the other earths found in soils by its ready so- 
 lubility in solutions of alkaline carbonates saturated with 
 carbonic acid. It appears to consist of 38 magnesium 
 and 15 oxygene. 
 
 5. There are two well known oxides of iron, the black 
 and the brown. The black is the substance tiiat flies off 
 when red hot iron is hammered. The brown oxide may 
 be formed by keeping the black oxide red hot, for a long 
 time in contact with air. The first seems to consist of 
 one proportion of iron 103, and two of oxygene 30 ; and 
 and the second of one proportion of iron 103, and three 
 proportions of oxygene 45. The oxides of iron some- 
 times exist in soils combined with carbonic acid. They 
 are easily distinguished from other substances by their 
 giving when dissolved in acids a black colour to solu- 
 
Ill 
 
 tiou of galls, and a bright blue precipitate to solution of 
 prussiate of potassa and iron. 
 
 6. The oxide of manganesum is the substance com- 
 monly called manganese, and used in bleaching. It ap- 
 pears to be composed of one proportion of manganesum 
 113, and three of oxygene 45. It is distinguished from 
 the other substances found in soils, by its property of 
 decomposing muriatic acid, and converting it into chlo- 
 rine. 
 
 Vegetable and animal matters are known by their sen- 
 sible qualities, and by their property of being decompo- 
 sed by heat. Their characters may be learnt from the 
 details in the last Lecture. 
 
 8. The saline compounds found in soils, are common 
 salt, sulphate of magnesia, sometimes sulphate of iron, 
 nitrates of lime and of magnesia, sulphate of potassa, 
 and carbonates of potassa and soda. To describe their 
 characters minutely will be unnecessary; the tests, for 
 most of them have been noticed p. 81. 
 
 The silica in soils is usually combined with alumina 
 and oxide of iron, or with alumina, lime, magnesia and 
 oxide of iron, forming gravel and sand of different de- 
 grees of fineness. The carbonate of lime is usually in 
 an impalpable form : but sometimes in the state of cal- 
 careous sand. The magnesia, if not combined in the 
 gravel and sand of soil, is in a fine powder united to 
 carbonic acid. The impalpable part of the soil, which 
 is usually called clay or loam, consists of silica, alumi- 
 na, lime, and magnesia ; and is, in fact, usually of the 
 same composition as the hard sand, but more finely di- 
 vided. The vegetable, or animal matters, (and the first 
 is by far the most common in soils) exist in different 
 states of decomposition. They are sometimes fibrous, 
 sometimes entirely broken down and mixed with the 
 soil. 
 
 To form a just idea of soils, it is necessary to conceive 
 different rocks decomposed, or ground into parts and 
 powder of different degrees of fineness ; some of their 
 soluble parts dissolved by water, and that water adhe- 
 ring to the mass, and the whole mixed with larger or 
 smaller quantities of the remains of vegetables and ani- 
 mals in different stages of decay. 
 
112 
 
 It will be necessary to describe the processes by whicli 
 all the varieties of soil may be analysed. I shall be mi- 
 nute in these particulars, and, I fear, tedious ; but the 
 philosophical farmer will, 1 trust, feel the propriety of 
 full details on this subject. 
 
 The instruments required for the analysis of soils are 
 few, and but little expensive. They are a balance ca- 
 pable of containing a quarter of a pound of common soil, 
 and capable of turning when loaded, with a grain ; a set 
 of weights from a quarter of a pound troy to a grain ; a 
 wire sieve, sufficiently coarse to admit a mustard seed 
 through its apertures ; an Argand lamp and stand ; some 
 glass bottles ; Hessian crucibles ; porcelain, or queen's 
 ware evaporating basins ; a Wedgewood pestle and 
 mortar ; some filtres made of half a sheet of blotting pa- 
 per, folded so as to contain a pint of liquid, and greased 
 at the edges ; a bone knife, and an apparatus for col- 
 lecting and measuring aeriform fluids. 
 
 The chemical substances or reagents required for se- 
 parating the constituent parts of the soil, have, for the 
 most part, been mentioned before : they are muriatic acid 
 {spirit of salt,) sulphuric acid, pure volatile alkali dis- 
 solved in water, solution of prussiate of potash and iron, 
 succinate of ammonia, soap lye, or solution of potassa, 
 solutions of carbonate of ammonia, of muriate of ammo- 
 nia, of neutral carbonate of potash, and nitrate of ammo- 
 niac. 
 
 In cases when the general nature of the soil of a field 
 is to be ascertained, specimens of it sliould be taken from 
 different places, two or three inches below the surface,, 
 and examined as to the similarity of their properties. It 
 sometimes happens, that upon plains the whole of the 
 upper stratum of the land is of the same kind, and in 
 this case, one analysis will be sufficient; but in valleys, 
 and near the beds of rivers, there are very great differ- 
 ences, and it now and then occurs that one part of a field 
 is calcareous, and another part siliceous ; and in this 
 case, and in analogous cases, the portions different from 
 each other should be separately submitted to experi- 
 ment. 
 
 Soils when collected, if they cannot be immediately 
 examined, should be preserved in phials quite filled with 
 them, and closed with ground glass stoppers. 
 
113 
 
 The quantity of soil most convenient for a perfect 
 analysis, is from two to four hundred grains. It should 
 be collected in dry weather, and exposed to the atmos- 
 phere till it becomes dry to the touch. 
 
 The specific gravity of a soil, or the relation of its 
 weight to that of water, may be ascertained by introdu- 
 cing into a phial, which will contain a known quantity 
 of water, equal volumes of water and of soil, and this 
 may be easily done by pouring in water till it is half full, 
 and then adding the soil till the fluid rises to the mouth; 
 the difterence between the weight of tiie soil and that 
 of the water, will give the result. Thus if the bottle 
 contains four hundred grains of water, and gains two 
 liundred grains when half filled with water and half 
 with soil, the specific gravity of the soil will be 2, that 
 is, it will be twice as heavy as water, and if it gained 
 one hundred and sixty-five grains, its specific gravity 
 would be 1825, water being 1000. 
 
 It is of importance, that the specific gravity of a soil 
 should be known, as it affords an indication of the quan- 
 tity of animal and vegetable matter it contains ; these 
 substances being always most abundant in the lighter 
 soils. 
 
 The other physical properties of soils should likewise 
 be examined before the analysis is made, as they de- 
 note, to a certain extent, their composition, and serve as 
 guides in directing the experiments. Thus siliceous 
 soils are generally rough to the touch, and scratch glass 
 when rubbed upon it; ferruginous soils are of a red or 
 yellow colour ; and calcareous soils are soft. 
 
 1 . Soils, though as dry as they can be made by con- 
 tinued exposure to air, in all cases still contain a con- 
 siderable quantity of water, which adiieres with great 
 obstinacy to the earths and animal and vegetable mat- 
 ter, and can only be driven off from them by a consi- 
 derable degree of heat. The first process of analysis 
 is, to free the given weight of soil from as much of this 
 water as possible, without in other respects, affecting its 
 composition ; and this may be done by heating it for ten 
 or twelve minutes over an Argand's lamp, in a basin of 
 porcelain, to a temperature equal to 300 Fahrenheit ; 
 and if a thermometer is not used, the proper degree 
 
114 
 
 may be easily ascertained, by keeping a piece of wood 
 in contact with tlie bottom of the dish ; as long as the 
 colour of tlie wood remains unaltered, the heat is not 
 too high ; hut when the wood begins to be cliarred, the 
 process must lie stopped. A small quantity of water 
 will perhaps remain in the soil even after this operation, 
 but it always atlbrds useful comparaiive results ; and if 
 a higher temperature were emplo^yed, the vegetable or 
 animal matter would undergo deufrrrposition, and in 
 consequence the experiment be wholly unsatisfactory. 
 
 The loss of \\ eight in the process should be carefully 
 noted, and when in four hundred grains of soil it 
 readies as high as 50, the soil may be considered as in 
 the greatest degree absorbent, and retentive of water, 
 and will generally be found to contain much vegetable 
 or animal matter, or a large proportion of aluminous 
 earth. When the loss is only from 20 to 10, the land 
 may be considered as only slightly absorbent and reten- 
 tive, and siliceous earth probably forms the greatest 
 part of it. 
 
 2. None of the loose stones, gravel, or large vegeta- 
 ble fibres should be divided from the pure soil till after 
 the water is drawn oft'; for these bodies are themselves 
 often highly absorbent and retentive, and in consequence 
 influence the fertility of the land. The next process, 
 however, after that of heating, should be their separa- 
 tion, which may be easily accomplished by the sieve, 
 after the soil has been gently bruised in a mortar. The 
 weights of the vegetable fibres or wood, and of the gra- 
 vel and stones should be separately noted down, and 
 the nature of the last ascertained ; if calcarious, they 
 will efl'ervesce with acids; if siliceous, they will be suf- 
 ficiently hard to scratch glass ; and if of the common 
 aluminous class of stones, they w ill be soft, easily cut 
 with a knife, and incapable of effervescing with acids. 
 
 3. The greater number of soils, besides gravel and 
 stones, contain larger or smaller proportions of sand of 
 different degrees of fineness ; and it is a necessary ope- 
 ration, the next in the process of analysis, to detach 
 them from the parts in a state of more minute division, 
 such as clay, loam, marie, vegetable and animal matter, 
 and the matter, soluble in w ater. This mav be ett'ected 
 
115 
 
 iu a vvny suiRciently accurate by Ijoiliiig tlie soil in lliree 
 or four times its vveiglit of water; aud vvlieii the texture 
 of the soil is broken down, and the water cool ; by agi- 
 tating the parts together, and then suflVring tiiem to rest. 
 In this case, the coarse sand will generally separate in 
 a minute, and the finer in two or three minutes, whilst 
 the highly divided earthy, animal, or vegetable matter 
 will remain in a state of mechanical suspension for a 
 much longer time; so that by pouring the water from 
 the bottom of the vessel, after one, two, (u* three minutes, 
 the sand will be principally separated from the other 
 substances, which, with the water containing them, must 
 be poured into a filtre, and after the water has passed 
 through, collected, dried, and weighed. The sand must 
 likewise be weighed, and the respective quantities noted 
 down. The water of lixiviaticui must be preserved, as 
 it will be found to contain the saline and soluble animal 
 or vegetable matters, if any exist in the soil. 
 
 4. By the process of washing and filtration, the soil 
 is separated into two portions, the most important of 
 which is generally the finely divided matter. A minute 
 analysis of the sand is seldom or never necessary, and 
 its nature may be detected in the same manner as that 
 of the stones or gravel. It is always either siliceous 
 sand, or calcareous sand, or a mixture of both. ]f it 
 consist wholly of carljonate of lime, it will be rapidly 
 soluJde in muriatic acid, with effervescence ; Jjut if it 
 consist partly of this substance, and partly of siliceous 
 matter, the resjiective cpiantities may be ascertained by 
 weighing the residuum after the action of the acid, 
 which must be applied till the mixture has accjuired a 
 sour taste, and has ceased to effervesce. This residuum 
 is the siliceous part : it must be washed, dried and heat- 
 ed strongly in a crucible ; the difference between the 
 weight of it and the weight of the whole, indicates the 
 proportion of calcareous sand. 
 
 5. The finely divided matter of the soil, is usually 
 very compound in its nature ; it sometimes contains all 
 the four primitive earths of soil, as well as animal and 
 vegetable matter ; and to ascertain the proportions of 
 these with tolerable accuracy, is the most difficult part 
 of the subject. 
 
'VUv liisi pi'ocess to be pcrlbrmetl, in this part of the 
 anal;\His. is the exposure of the fine matter of the soil 
 to tlie adioii of muriatic aciil. This substance should 
 be poured upon the eartliy matter in an evaporating ba- 
 sin, in a qiinniity equal to twice the weight of the earthy 
 matter; but diluted with double its volume of water. 
 The mixture should be often stirred, and suftered tore- 
 main for au hour or an hour and a half, before it is ex- 
 amined. 
 
 If any carbounte of lime or of magnesia exist in the 
 soil, tiiey will IsaNe been dissolved in this time by the 
 acid, w hicji sometimes takes up likewise a little oxide 
 of iron : but very seldom any alumina. 
 
 The tluid should be passed through a filtre ; the solid 
 matter collected washed with rain water, dried at a mo- 
 derate heat and weighed. Its loss will denote the quan- 
 tity of solid matter taken up. The washings must be 
 added to the solution, which if not sour to the taste, 
 must be made so by the addition of fresh acid, when a 
 little solution of prussiate of potassa and iron, must be 
 mixed with tlie whole. If a l)lue precipitate occurs, it 
 denotes the presence of oxide of iron, and the solution 
 of the prussiate must be dropped in till no farther eftect 
 is produced. To ascertain its quantity, it must be col- 
 lected in the same manner as other solid precipitates, and 
 heated red ; the result is oxide of iron, which may be 
 mixed witli a little oxide of manganesum. 
 
 Into the fluid freed from oxide of iron, a solution of 
 neutralized carbonate of potash must be poured till all 
 eflervescence ceases in it, and till its taste and smell in- 
 dicate a considerable excess of alkaline salt. 
 
 The precipitate that tails down is carbonate of lime; 
 it must I)e collected on the filtre, and dried at a heat be- 
 low that of redness. 
 
 The remaining fluid must be boiled for a quarter of 
 an hour, Avhen the magnesia, if any exist, will be pre- 
 cipitated from it, combined with carbonic acid, and its 
 quantity is to be ascertained in the same manner as 
 that of the carbonate of lime. 
 
 If {iny minute proportion of alumina should, from pe- 
 culiar circumstances, be dissolved by the acid, it will be 
 found in the precipitate with the carbonate of lime, and 
 
117 
 
 it may be separated from it by boiling it lor a few mi- 
 nutes with soap lye, sufficient to cover the solid matter; 
 this siibstance dissolves alumina, without acting upon 
 carbonate of lime. 
 
 Should the finely divided soil be sufficiently calcare- 
 ous to eflervesce very strongly with acids, a very simple 
 method may be adopted for ascertaining the quantity of 
 carbonate of lime and one sufficiently accurate in all 
 common cases. 
 
 Carbonate of lime, in all its states, contains a deter- 
 minate proportion of carbonic acid, i. e. nearly 43 per 
 cent, so that when the quantity of this elastic fluid, gi- 
 ven out by any soil during tlie solution of its calcareous 
 matter in an acid is known, either in weight or mea- 
 sure, the quantity of carbonate of lime may be easily 
 discovered. 
 
 When the process by diminution of weight is em- 
 ployed, two parts of the acid and one part of the matter 
 of the soil must be weighed in two separate bottles, and 
 very slowly mixed together till the eJQPervescence ceases ; 
 the dijfference between their weight before and after the 
 experiment, denotes the quantity of carbonic acid lost ; 
 for every four grains and a quarter of which, ten grains 
 of carbonate of lime must be estimated. 
 
 The best method of collecting the carbonic acid, so 
 as to discover its volume, is by a peculiar pneumatic ap- 
 paratus,* in which its hulk may be measured by the 
 quantity of water it displaces. 
 
 * Fig. 15. A, B, C, D, represent the different parts of tliis appar- 
 atus. A. Represents tlie bottle for receiving the soil. B. 'I'he bot- 
 tle containing the acid, furnished with a stop-cock. C. The tube 
 connected with a flaccid bladder. D. The graduated measure. E. 
 The bottle for containing the bladder. When this instrument is 
 used, a given quantity of soil is introduced into A. B ib fiiied witti 
 muriatic acid diluted with an equal quantity of water; and the stop- 
 cock being closed, is connected with the upper orifice of A, which is 
 ground to receive it. Tlie tube D is introduced into the lower ori- 
 fice of A, and the. bladder connected wiih it placed in its flaccid state 
 into E. which is fiiied with water. The graduated measure is placed 
 under the tube of E. When the stop-cock of B is turned, the acid 
 flows into A, and acts upon the soil ; the elastic fluid generated 
 passes through C into the bladder, and displaces a quantity of water 
 in E equal to it in bulk, and this water flows through the tube into 
 the graduated measure: and gives by its volume the indication of the 
 proportion of carbonic acid disengaged from the soil ; for every ounce 
 measure of which two grains of carbonate of lime may be estimated. 
 
118 
 
 6. After tlie calcareous parts of the soil has been act- 
 ed upon by muriatic acid, tlie uext process is to ascer- 
 taiu tlic quantity of finely divided insoluble animal and 
 vegetable matter that it contains. 
 
 lliis may be done with sufficient precision, by strong- 
 ly igniting it in a crucible over a common fire till no 
 blackness remains in the mass. It should be often stir- 
 red with a metallic rod, so as to expose new surfaces 
 continually to the air ; the loss of weight that it under- 
 goes denotes the quantity of the substance that it con- 
 tains destructible by fire and air. 
 
 It is not possible, without very refined and difficult 
 experiments, to ascertain whether this substance is whol- 
 ly animal or vegetable matter, or a mixture of both. 
 When the smell emitted during the incineration is simi- 
 milar to that of burnt feathers, it is a certain indication 
 of some substance either animal or analogous to animal 
 matter ; and a copious blue flame at the time of ignition, 
 almost always denotes a considerable proportion of ve- 
 getable matter. In cases when it is necessary that the 
 experiment should be very quickly performed, the de- 
 struction of the decomposable substances may be assist- 
 ed by the agency of nitrate of ammoniac, which at the 
 time of ignition may be thrown gradually upon the heat- 
 ed mass in the quantity of twenty grains for every hun- 
 dred of residual soil. It accelerates the dissipation of 
 the animal and vegetable matter, which it causes to be 
 converted into elastic fluids ; and it is itself at the same 
 time decomposed and lost. 
 
 7. The substances remaining after the destruction of 
 the vegetable and animal matter, are generally minute 
 particles of earthy matter, containing usually alumina 
 and silica, with combined oxide of iron or of mangane- 
 sum. 
 
 To separate these from each other, the solid matter 
 should be boiled for two or three hours with sulphuric 
 acid, diluted with four times its weight of water ; the 
 quantity of the acid should be regulated by the quanti- 
 ty of solid residuum to be acted on, allowing for every 
 hundred grains, two drachms or one hundred and twen- 
 ty grains of acid. 
 
 The substance remaining after the action of the acid. 
 
1 19 
 
 may bu consickred as siliceous ; and it must be separa- 
 ted and its wei^^ht ascertained, after washini^ and dry- 
 ing in tiie usual manner. 
 
 Tbe alumina and tlie oxide of iron and manganesum, 
 if any exist, are all dissolved by the sulpluiric acid ; 
 they may be separated by succinate of ammonia, added 
 to excess ; which throws down the oxide of iron, and 
 by soap lye, which will dissolve the alumina, but not 
 the oxide of manganesum : the weights of theoxides as- 
 certained after they have been heated to redness will de- 
 note their quantities. 
 
 Should any magnesia and lime have escaped solution 
 in the muriatic acid, they will be found in the sulphuric 
 acid : this, however, is rarely the case ; but the process 
 for detecting them, and ascertaining their quantities, is 
 the same in both instances. 
 
 The method of analysis by sulphuric acid, is suffi- 
 ciently precise for all. usual experiments ; but if very 
 great accuracy be an object, dry carbonate of potassa 
 must be employed as the agent, and the residuum of the 
 incineration (6) must be heated red for a half hour, with 
 four times its weight of this substance, in a crucible of 
 silver, or of well baked porcelain. The mass obtained 
 must be dissolved in miaiatic acid, and the solution 
 evaporated till it is nearly solid ; distilled water must 
 then be added, by which the oxide of iron and all the 
 earths, except silica, will be dissolved in combination 
 as muriates. The silica, after the usual process of lixi- 
 viation, must be heated red ; the other substances may 
 be separated in the same manner as from the muriate 
 and sulphuric solutions. 
 
 This process is the one usually employed by chemi- 
 cal philosophers for the analysis of stones. 
 . 8. If any saline matter, or soluble vegetable or ani- 
 mal matter is suspected in the soil, it will be found in 
 the water of lixiviation used for separating the sand. 
 
 This water must be evaporated to dryress in a pro- 
 per dish, at a heat below its boiling point. 
 
 If the solid matter oI)tained is of a brown colour and 
 inflammable, it may be considered as partly vegetable 
 extract. If its smell, when exposed to heat, be like 
 that of burnt feathers, it contains animal or albuminous 
 
120 
 
 luaLlcr; if it Ui." while, crystalliiic, and not dcslructihli 
 hy iicat, it may he cousitlciTtl as |)riiuu|>all,Y saline mat- 
 ivv; llic naluio of uliich may he known by tlic tests 
 (lesniheil pa^r 81, 
 
 9. Shonld snlpliate or pliospliate of lime ho snspect- 
 C(l in the entire soil, Ihe delection of tlieni requires a 
 particnhir i)ro( ess upon it. A i:;iven \veii;ht of il, for in- 
 stance, four huiulred i^rains, nuist he heated red for lialf 
 an hour in a i rut ihU», mixed with oue-tinrd of powder- 
 ed (harcoal. The mixture must l>e hoiU'd fora([uarter 
 of an hour, in a half pint of water, and the thiid col- 
 lected (hrouj;i» the filtre, and exposed for some days to 
 tlie almospliere in an open vessel. If any notable (pnm- 
 tity of sul[)hate of lime (i;ypsum) existed in the soil, a 
 while precipitate will i;ra<lually form in the iluid, and 
 tin» weii;ht of it will indicate the proportion. 
 
 l*hos[)ha(e of lime, if any exist, may he separated from 
 the soil after Ihe process IVu" i;ypsum. Mnrialic acid 
 must be digested upon the soil, in ([uantity more than 
 snflicient to salurale the soluble earths ; Ihe solution must 
 be evaporatetl, and waler poure«l upon the soTul matter. 
 This Iluid w ill dissolve the (impounds of earths with 
 the muriatic acid, and leave the phosphate of lime un- 
 touched. 
 
 It would not fall within the limits assi:;ned to this 
 Lecture, to detail any processes for the detection of sub- 
 stances which may be accidentally mixed with the mat- 
 ters of soils. Other earths and metallic oxides are now 
 and then found in them, but in (piantities too minute to 
 bear anv relation to fertilitv or barrenness, and the search 
 for them would make the analysis much more complica- 
 ted without renderiiii; it nnue useful. 
 
 10. When the examination of a soil is conqdeled, the 
 products should be numerically arrani;ed, and their 
 (piantities adiled toi;ether, and if they nearly equal the 
 orii;inal <iuantily of soil, the analysis may be consider- 
 ed as accurate. It must, however, be noticed, that when 
 [)lu)sphate or sulphate of lime are discovered by Ihe in- 
 depeu»lent process just »lescribed, (i>.) a ct)rrection must, 
 be nuule l\tr the i;eneral process, by subtractinj:; a sum 
 ecpial to their wei:;ht from the <|uantily of carbonate of 
 lin\e, ohtaimMl by precipitation from the muriatic acid. 
 
121 . 
 
 Tii arraiii^ing the products, the rorin should be in tiic 
 order of llie exporimiMits l>y wliich ihvy were, procured. 
 
 Thus, 1 obtained from 401) i^rains of a p)od siliceous 
 sandy soil from a bop garden near Tunbridge, Kent, 
 
 (i rains. 
 
 Of water of absorption - - - - 19 
 
 Of loose stones and i:;ravel principally siliceous 53 
 
 Of undecompounded vej^etable fibres - - 14 
 
 Of fine siliceous sand ----- 212 
 Of minutely divided matter se|)arated by agitation 
 and filtration, and consisting of 
 
 Carbonate of lime 19 
 
 Carbonate of magnesia . . . . 3 
 Matter destructible by beat, principally vegeta- 
 ble 15 
 
 Silica ------- 21 
 
 Alumina 13 
 
 Oxide of iron ------ 5 
 
 Soluble matter, principally common salt and vege- 
 table extract - _ - , . 3 
 Gypsum 2 
 
 Amount of all the products 379 
 Loss - - - - 21 
 
 The loss in this analysis is not more than usually oc- 
 curs, and it depetids upon the impossibility of collect- 
 ing the whole (piantities of the jliflerent precipitates; 
 and upon the presence of more moisture than is account- 
 ed for in the water of absorption, and which is lost in 
 the difl'erent processes. 
 
 When the experimenter is become acquainted witli 
 the use of the dilferent instruments, the jiroperties of the 
 reagents, and the relations betwcien the> external and 
 chemical qualities of soils, he will seldom find it neces- 
 sary to perform, in any one case, all tin; processes that 
 have been descril»ed. When his soil, for instance, con- 
 tains no notable pro|)ortion of calcareous matter, the ac- 
 tion of the muriatic acid (7) may be omitted. In exam- 
 ining peat soils, he will principally have to attend to the 
 operation by fire and air (8 ;) and in the analysis of 
 
 Q 
 
122 
 
 chalks a'lul loams, lie will often be able to omit the ex- 
 periment by sulphuric acid (9.) 
 
 In the first trials that are made by persons unacquaint- 
 ed with chemistry, they must not expect much precision 
 of result. Many difficulties will be met with : but in 
 overcomiug tliem, the most useful kind of practical know- 
 ledge will he ohtained ; and nothing is so instructive in 
 experimentjjl science, as the detection of mistakes. The 
 correct analyst ougiit to be well grounded in general 
 chemical information ; but perhaps there is no better 
 mode of gaining it, than that of attempting original in- 
 Testigations. In pursuing his experiments he will be 
 continually obliged to learn the properties of the sub- 
 stances he is employing or acting upon ; and his theo- 
 retical ideas will be more valuable in being connected 
 with practical operations, and acquired for the purpose 
 of discovery. 
 
 Plants being possessed of no locomotive powers, can 
 grow only in places where they are supplied with food; 
 and the soil is necessary to their existence, both as af- 
 fording them nourishment, and enabling them to fix them- 
 selves in such a manner as to obey those mechanical 
 laws by which their radicles are kept below the surface, 
 and their leaves exposed to the free atmosphere. As 
 the systems of roots, branches and leaves are very dif- 
 ferent in difterent vegetables, so they flourish most in 
 diflerent soils, the plants that have bulbous roots require 
 a looser and a lighter soil than such as have fibrous 
 roots ; and the plants possessing only short fibrous radi- 
 cles demand a firmer soil than such as have tap roots, 
 or extensive lateral roots. 
 
 A good turnip soil from Holkham, Norfolk, afforded 
 me eight parts out of nine silicious sand ; and the fine- 
 ly divided matter consisted 
 
 Of Carbonate of lime - - 63 
 
 — Silica - - - - 15 
 
 — Alumina - - - - 11 
 
 — Oxide of iron . . - 3 
 
 — Vegetable and saline matter 5 
 
 — Moisture . . . - - 3 
 
128 
 
 I found the soil taken from a iiekl at Sheffield-place 
 in Sussex, remarkable for producing flourishing oaks, to 
 consist of six parts of sand, and one part of clay and 
 finely divided matter. And one hundred parts of the 
 entire soil submitted to analysis, produced 
 
 Parts. 
 
 Silica - - - - 54 
 
 Alumina - - - - 28 
 
 Carbonate of lime - - 3 
 
 Oxide of iron - - - - 5 
 
 Decomposing vegetable matter 4 
 
 Moisture and loss - - 3 
 
 An excellent wheat soil from the neighbourhood of 
 West Drayton, Middlesex, gav« three parts in five of 
 silicious sand ; and the finely divided matter consist- 
 ed of 
 
 Carbonate of lime - - - 28 
 Silica - - - - - 32 
 Alumina - - - - 29 
 
 Animal or vegetable matter and 
 moisture 
 
 11 
 
 Of these soils the last was by far the most, and the 
 first the least, coherent in teiiLture. In all cases the con- 
 stituent parts of the soil which give tenacity and cohe- 
 rence are the finely divided matters ; and they possess 
 the power of giving those qualities in the highest degree 
 when they contain much alumina. A small quantity of 
 finely divided matter is sufficient to fit a soil for the pro- 
 duction of turnips and barley ; and I have seen a tole- 
 rable crop of turnips on a soil containing 11 parts out 
 of twelve sand. A much greater proportion of sand 
 however, always produces absolute sterility. The soil 
 of Bagshot heath, which is entirely devoid of vegeta- 
 ble covering, contains less than ^V of finely divided mat- 
 ter. 400 parts of it, which had been lieated red, afford- 
 ed me 380 parts of coarse siliceous sand ; 9 parts of fine 
 siliceous sand, and 11 parts of impalpable matter, which 
 was a mixture of ferruginous clay, with carbonate of lime. 
 Vegetable or animal matters, when finely divided, not 
 
only give coherence, but likewise softness and penetia- 
 bility ; but neither they nor any other part of the soil 
 must he in too great proportion ; and a soil is uopro- 
 ductive if it consist entirely of impalpable matters. 
 
 Pure alumina or silica, pure carboi\atc of lime, or 
 carbonate of magnesia, are incapable of supporting heal- 
 thy vegetation. 
 
 No soil is fertile that contains as much as 19 parts 
 out of 20 of any of the constituents that have been men- 
 tioned. 
 
 It Avill be asked, are the pure earths in the soil mere- 
 .ly active as mechanical or indirect chemical agents, or 
 do they actually afford food to the plant ? This is an 
 important question ; and not tlifficult of solution. 
 
 The earths consist^ as 1 have before stated, of me- 
 tals united to oxygene ; and these metals have not been 
 decomposed ; there is consequently no reason to suppose 
 that the earths are convertible into the elements of or- 
 ganized compounds, into carbon, hydrogene, and azote. 
 
 Plants have been made to grow in given quantities of 
 earth. They consume very small portions only ; and 
 what is lost may be accounted for by the quantities found 
 in their ashes ; that is to say, it has not been converted 
 into any new products. 
 
 The carbonic acid united to lime or magnesia, if any 
 stronger acid happens to be formed in the soil during 
 the fermentation of vegetable matter which will disen- 
 gage it from the earths, may be decomposed ; but the 
 earths themselves cannot be supposed convertible into 
 other substances, by any, process taking place in the 
 soil. 
 
 In all cases the ashes of plants contain some of the 
 earths of the soil in which they grow; but these earths, 
 as may be seen from the table of the ashes afforded by 
 different plants given in the last Lecture, never equal 
 more than A of the weight of the plant consumed. 
 
 If they be considered as necessary to the vegetable, 
 it is as giving hardness and firmness to its organization. 
 Thus, it has been mentioned that wheat, oats, and ma- 
 ny of the hollow grasses, have an epidermis principally 
 of siliceous earth ; the use of which seems to be to 
 
125 
 
 strengthen them, and defend them from the attacks of 
 of insects and parasitical plants. 
 
 Many soils are popiilarl j distinguished as cold ; and 
 the distinction, though at first view it may appear to he 
 founded on prejudice, is really just. 
 
 Some soils are much more heated by the rays of the 
 sun, all other circumstances being equal, than others ; 
 and soils brought to the same degree of heat cool in dif- 
 ferent times, i. e. some cool much faster than others. 
 
 This property has been very little attended to in a 
 philosophical point of view ; yet it is of the highest im- 
 portance in agriculture. In general, soils that consist 
 principally of a stiff white clay are difficultly heated ; 
 and being usually very moist, they retain their heat on- 
 ly for a short time. Chalks are similar in one respect, 
 that they are difficultly heated ; but being drier they re- 
 tain their heat longer, less being consumed in causing 
 the evaporation of their moisture. 
 
 A black soil, containing mucli soft vegetable matter, 
 is most heated by the sun and air ; and the coloured 
 soils, and the soils containing much carbonaceous mat- 
 ter, or ferruginous matter, exposed under equal circum- 
 stances to sun, acquire a much higher temperature than 
 pale-coloured soils. 
 
 When soils are perfectly dry, those that most readi- 
 ly become heated by the solar rays likewise cool most 
 rapidly ; but 1 liave ascertained by experiment, that the 
 darkest coloured dry soil (that which contains abun- 
 dance of animal or vegetable matter ; substances which 
 most facilitate the diminution of temperature,) when heat- 
 ed to the same degree, provided it be within the common 
 limits of the effect of solar heat, will cool more slowly 
 than a wet pale soil, entirely composed of earthy matter. 
 
 1 found tliat a ricli black mould, which contained near- 
 ly \ of vegetable matter, had its temperature increased 
 in an hour from 65^^ to 88^ by exposure to sunshine ; 
 whilst a chalk soil was heated only to 69^ under the 
 same circumstances. But the mould removed into the 
 shade, wliere the temperature was 62°, lost, in half an 
 hour, 15° ; whereas the chalk, under the same circum- 
 stances, had lost only 4°. 
 
 A brown fertile soil, and a cold barren clay were each 
 
126 
 
 artificially heated to 88°, having beeu previously dried : 
 they were then exposed in a temperature of 57°; in half 
 an hour the dark soil was found to have lost 9° of heat ; 
 the clay had lost only 6°. An equal portion of the clay 
 containing moisture, after being heated to 88°, was ex- 
 posed in a temperature of 55° ; in less than a quarter of 
 an hour it was found to have gained the temperature of 
 the room. The soils in all these experiments were pla- 
 ced in small tin plate trays two inches square, and half 
 an inch in depth ; and tlie temperature ascertained by a 
 delicate thermometer. 
 
 Nothing can be more evident, than that the genial 
 heat of the soil, particularly in spring, must be of the 
 highest importance to the rising plant. And when the 
 leaves are fully developed, the ground is shaded ; and 
 any injurious influence, M'hicli in the summer might be 
 expected from too great a heat, entirely prevented : 
 so that the temperature of the surface, when bare and 
 exposed to the rays of the sun, aflbrds at least one indi- 
 cation of the degrees of its fertility ; and the thermo- 
 meter may be sometimes a useful instrument to the pur- 
 chaser or improver of lands. 
 
 The moisture in the soil influences its temperature ; 
 and the manner in which it is distributed through, or 
 combined with, the earthy materials, is of great impor- 
 tance in relation to the nutriment of the plant. If wa- 
 ter is too strongly attracted by the earths, it will not be 
 absorbed by the roots of the plants : if it is in too great 
 quantity, or too loosely united to them, it tends to in- 
 jure or destroy the fibrous parts of the roots. 
 
 There .are two states in which water seems to exist 
 in the earths, and in animal and vegetable substances : 
 in the first state it is united by chemical, in the other by 
 cohesive, attraction. 
 
 If pure solution of ammonia or potassabe poured into 
 a solution of alum, alumina falls down combined with 
 w^ater : and the powder dried by exposure to air will 
 aftbrd more than half its weight of water by distilla- 
 tion ; in this instance the water is united by chemical 
 attraction. The moisture which wood, or muscular 
 fibre, or gum, that have been heated to 212°, afford by 
 distillation at a red heat, is likewise water, the elements 
 
127 
 
 of wliich were united in the substance by chemical com- 
 bination. 
 
 When pipe-clay dried in the temperature of the at- 
 mosphere is brought in contact with water, the fluid is 
 rapidly absorbed ; this is owing to cohesive attraction. 
 Soils in general, vegetable, and animal substances, that 
 have been dried at a heat below that of boiling water, 
 increase in weight by exposure to air, owing to their ab- 
 sorbing water existing in the state of vapour in the air, 
 in consequence of cohesive attraction. 
 
 The water chemically comhined amongst the elements 
 of soils, unless in the case of the decomposition of ani- 
 mal or vegetable substances, cannot be absorbed by the 
 roots of plants ; but that adhering to the parts of the 
 soil is in constant use in vegetation. Indeed there are 
 few mixtures of the earths found in soils, that contain 
 any chemically combined water; water is expelled from 
 the earths by most substances that combine with them. 
 Thus, if a combination of lime and water be exposed 
 to carbonic acid, the carbonic acid takes the place of 
 water ; and compounds of alumina and silica, or other 
 compounds of the earths, do not chemically unite with 
 water : and soils, as it has been stated, are formed either 
 by earthy carbonate*^, or compounds of the pure earths 
 and metallic oxides. 
 
 When saline substances exist in soils, they may be 
 united to water both chemically and mechanically ; but 
 they are always in too small a quantity to influence ma- 
 terially the relations of the soil to water. 
 
 The power of the soil to absorb water by cohesive 
 attraction, depends in great measure upon the state of 
 division of its parts ; the more divided they are, the 
 greater is their absorbent power. The dift'erent con- 
 stituent parts of soils likewise appear to act, even by 
 cohesive attraction, with different degrees of energy. 
 Thus vegetable substances seem to be more absorbent 
 than animal substances ; animal substances more so than 
 compounds of alumina and silica ; and compounds of 
 alumina and silica more absorbent than carbonates of 
 lime and magnesia: these diflferences may, however, 
 possibly depend upon the differences in theirstate of di- 
 \ision, and upon the surface exposed. 
 
128 
 
 The power of soils to absorb water from air, is much 
 connected with fertility. When this power is great, 
 the plant is supplied with moisture in dry seasons; and 
 the effect of evaporation in the day is counteracted by 
 the absorption of aqueous vapour from the atmosphere, 
 by the interior parts of the soil during the day, and by 
 both the exterior and interior during night. 
 
 The stiff clays approaching to pipe-clays in their na- 
 ture, which take up the greatest quantity of water when 
 it is poured upon them in a fluid form, are not the soils 
 which absorb most moisture from the atmosphere in dry 
 weather. They cake, and present only a small surface 
 to the air ; and the vegetation on them is generally burnt 
 up almost as readily as on sands. 
 
 The soils that are most efficient in supplying the plant 
 with water by atmospheric absorption, are those in which 
 there is a due mixture of sand, finely divided clay, and 
 carbonate of lime, with some animal or vegetable mat- 
 ter : and wiiich are so loose and light as to be freely 
 permeable to the atmosphere. With respect to this 
 quality, carbonate of lime and animal and vegetable 
 matter are of great use in soils ; they give absorbent 
 power to the soil without giving U likewise tenacity : 
 sand, which also destroys tenacity, on the contrary, 
 gives little absorbent power. 
 
 I have compared the absorbent powers of many soils 
 with respect to atmospheric moisture, and I have always 
 found it greatest in the most fertile soils ; so that it af- 
 fords one method of judging of the productiveness of 
 land. 
 
 1000 parts of a celebrated soil from Ormiston, in 
 East Lothian, w hich contained more than half its weight 
 of finely divided matter, of which 11 parts were car- 
 bonate of lime, and nine parts vegetable matter, when 
 dried at 212^*, gained in an hour by exposure to air sa- 
 turated with moisture, at temperature 62°, 18 grains. 
 
 lOOO'parts of a very fertile soil from the banks of the 
 river Parret, in Somersetshire, under the same circum- 
 stances, gained 16 grains. 
 
 1000 parts of a soil from Mersea, in Essex, worth 
 45 shillings an acre, gained 1-3 grains. 
 
129 
 
 1000 grains of a fine sand from Essex, worth 28 shil- 
 lings an acre, gained 11 grains. 
 
 1000 of a coarse sand worth 15 shillings an acre, 
 gained only eight grains. 
 
 1000 of the soil of Bagshot-heath gained only three 
 grains. 
 
 Water, and the decomposing animal and viigetahle 
 matter existing in the soil, constitute the true nourish- 
 ment of plants ; and as the earthy parts of the soil are 
 useful in retaining water, so as to suj)ply it in the proper 
 proportions to the roots of the vegetables, so they arc 
 likewise eflBcacious in producing the proper distribution 
 of the animal or vegetable matter ; when equally mixed 
 with it they prevent it from decomposing too rapidly ; 
 and by their means the soluble parts are supplied in 
 proper proportions. 
 
 Besides this agency, which may be considered as me- 
 chanical, there is another agency between soils and or- 
 ganizable matters, which may be regarded as chemical 
 in its nature. The earths, and even the earthy carbo- 
 nates, have a certain degree of chemical attraction for 
 many of the principles of vegetable and animal substan- 
 ces. This is easily exemplified in the instance of alu- 
 mina and oil ; if an acid solution of alumina be mixed 
 with a solution of soap, which consists of oily matter 
 and potassa; the oil and the alumina will unite and 
 form a white powder, which will sink to the bottom of 
 the fluid. 
 
 The extract from decomposing vegetable matter when 
 boiled with pipe-clay or chalk, forms a combination by 
 which the vegetable matter is rendered more difficult 
 of decomposition and of solution. Pure silica and sili- 
 ceous sands have little action of this kind ; and the soils 
 which contain the most alumina and carbonate of lime are, 
 these which act with the greatest chemical energy in pre- 
 serving manures. Such soils merit the appellation which 
 is commonly given to them of rich soils; for the vegeta- 
 ble nourishment is long preserved in them, unless taken 
 up by the organs of plants. Siliceous sands, on the 
 contrary, deserve the term hungry, wliich is commonly 
 applied to them ; for the vegetable and animal matters 
 they contain not being attracted by the earthy constitu- 
 
 R 
 
130 
 
 ml; parts of the soil, arc more liable to be decomposed 
 b.y the action of the atmosphere, or carried oil' from them 
 by M aler. 
 
 i II most of ihe black and brown rich vegetable moulds, 
 the earths seem to be in combination with a peculiar ex- 
 tractive matter, alVorded during the decomposition of ve- 
 2;etables : tiiis is slowly taken up, or attracted from the 
 earths by water, and appears to constitute a prime cause 
 of the fertility of the soil. 
 
 The staiuhu-d of fertility of soils for different plants 
 must vary with the climate; and must be particularly 
 inlluenced by the quantity of rain. 
 
 'J he power of soils to absorb moisture ought to be 
 much greater in \> arm or dry counties, than in cold and 
 moist ones ; and the (piantity of clay, or vegetable or 
 animal matter they contain greater. Soils also on de- 
 clivities ought to be more absorbent than in i>lains or in 
 the bottom of vallies. Their pnuluctiveness likewise 
 is inlluenced by the nature of the subsoil or the stratum 
 on which they rest. 
 
 \V hen soils are immediately situated upon a bed of 
 rock or stone, they are much sooner rendered dry by 
 evaporation, than wiiere the subsoil is of clay or marie; 
 and a prime cause of liie great fertility of the land in 
 tlse moist climate of Ireland, is the proximity of the 
 rocky strata to the soil. 
 
 A clayey subsoil will sometimes be of material advan- 
 tage to a sandy soil ; and in this case it w ill retain mois- 
 ture in such a manner as to be capable of supplying that 
 lost by the earth above, in consequence of evaporation, 
 or the consumption of it by plants. 
 
 A sandy, or gravelly suhsoil, often corrects the im- 
 perfections of too great a degree of absorbent poMer in 
 the true soil. 
 
 In calcareous countries, where the surface is a spe- 
 cies of marie, the soil is often found only a few inches 
 above the limiestone; and its fertility is not impaired by 
 the proximity of the rock ; though in a less absorbent 
 soil, this situation would occasion barrenness ; and the 
 sandstone and limestone hills in Derbyshire and North 
 Wales, may be easily distinguished at a distance in 
 summer ])y the different tints of the vegetation. The 
 
131 
 
 grass on the sandstone hills usually appears brown and 
 Imrnt up; that on the limestone hills liourishinti; and 
 green. 
 
 In devoting the diflerent parts of an estate to the ne- 
 cessary crops, it is perfectly evident from what has been 
 said, that no general principle can be laid down, except 
 when all the circumstances of the nature, composition, 
 and situation of the soil and subsoil are known. 
 
 The methods of cultivation likewise must be dift'er- 
 ent for different soils. The same practice which will 
 be excellent in one case may be destructive in ano- 
 ther. 
 
 Deep ploughing may be a very profitalile practice in 
 a rich thick soil ; and in a fertile shallow soil, situated 
 upon cold clay or sandy subsoil, it may be extremely 
 prejudicial. 
 
 In a moist climate where the (juantity of rain that 
 falls annually equals from 40 to 60 inches, as in Lanca- 
 shire, Cornwall, and some parts of Ireland, a siliceous 
 sandy soil is much more productive than in dry districts; 
 and in such situations, wheat and beans will re(|uire a 
 less coherent and absorlient soil than in drier situations ; 
 and plants having bulbous roots, will llourish in a soil 
 containing as much as 14 parts out of 15 of sand. 
 
 Even the exhausting powers of crops will be influen- 
 ced by like circumstances. In cases where plants can- 
 not absorb sufficient moisture, they must take up more 
 manure. And in Ireland, Cornwall, and the western 
 Highlands of Scotland, corn will exhaust less than in 
 dry inland situations. Oats, particularly in dry climates, 
 are impoverishing in a much higlier degree than in moist 
 ones. 
 
 Soils appear to have been originally produced in con- 
 sequence of the decomposition of rocks and strata. It 
 often happens that soils are found in an unaltered state 
 upon the rocks from which they were derived. It is 
 easy to form an idea of the manner in which rocks are 
 converted into soils, by referring to the instance of soft 
 granite, or jwrcelain granite. This substance consists 
 of three ingredients, quartz, feldspar, and mica. The 
 quartz is almost pure silicious earth, in a crystalline 
 form. The feldspar and mica are very compounded sub- 
 
stances ; Iiotli contain silica, alumina, and oxide of iron ; 
 in the IVldsjiar there is usually lime and potassa: in the 
 mica, lime and magnesia. 
 
 W'iien a granitic rock of tliis kind has been long ex- 
 posed to the intluencc of air and water, tlie lime and the 
 potassa contained in its constituent parts are acted upon 
 by water or carbonic acid ; and the oxide of iron, which 
 is almost always in its least oxided state, tends to com- 
 bine with more oxygene ; the consequence is, tliat the 
 feldspar decomposes, and likewise the mica; l)ut the first 
 the most rapidly. The felds|)ar, which is as it were the 
 cement of the stone, forms a tine clay: the mica partial- 
 ly decomposed mixes with it as sand; and thcundecom- 
 ])osed (|uart/- appears as gravel, or sand of different de- 
 grees of fuK'ness. 
 
 As soon as the smallest layer of earth is formed on the 
 surface of a rock, the seeds of lichens, mosses, and 
 other imperfect vegetables which are constantly floating 
 in the atmosphere, ami which have made it their rest- 
 ing place, begin to vegetate; their death, decomposition, 
 and decay, afford a certain quantity of organizable mat- 
 ter, which mixes with the earthy materials of the rock ; 
 in this improved soil more perfect plants are capable of 
 subsisting ; these in their turn absorb nourishment from 
 water and the atmosphere ; and after perishing, afford 
 new materials to those already provided : the decomposi- 
 tion of the rock still continues ; and at length by such 
 slow and gradual processes, a soil is formed in which even 
 forest trees can fix their roots, and which is fitted to re- 
 ward the labours of the cultivator. 
 
 In instances wiiere successive generations of vegeta- 
 bles have grown upon a soil, unless part of their pro- 
 duce has been carried off by man, or consumed by ani- 
 mals, the vegetable matter increases in such a propor- 
 tion, that the soil approaches to a peat in its nature ; 
 and if in a situation where it can receive water from a 
 higher district, it becomes spongy, and permeated with 
 that fluid, and is gradually rendered incapable of sup- 
 porting the nobler classes of vegetables. 
 
 Many peat- mosses seem to have been formed by the 
 destruction of forests, in consequence of the imprudent 
 use of the hatchet by the early cultivators of the conn- 
 
try ill wliich they exist: when the trees are felled in the 
 out-skirts of a wood, those in the interior exposed to the 
 influence of the winrls ; and havini:; been accustomed to 
 shelter, become unhealthy, and die in their new situa- 
 tion ; and their leaves and branches gradually decora- 
 j)osing, produce a stratum of vegetable matter. In ma- 
 ny of the great bogs in Ireland and Scotland, the larger 
 trees that are found in the out-skirts of them, bear the 
 marks of having been felled. In the interior few en- 
 tire trees are found ; and the cause is, probably, that 
 they fell by gradual decay ; and that the fermentation 
 and decomposition of the vegetable matter was most ra- 
 pid where it was in the greatest quantity. 
 
 Lakes and pools of water are sometimes filled up by 
 the accumulation of the remains of aquatic plants ; and 
 in this case a sort of spurious peat is formed. The fer- 
 mentation in these cases, however, seems to be of a dif- 
 ferent kind. Much more gaseous matter is ev(dved ; 
 and the neighbourhood of morasses in which aquatic ve- 
 getables decompose, is usually aguish and unhealthy ; 
 whilst that of the true peat, or peat formed on soils ori- 
 ginally dry, is always salubrious. 
 
 The earthy matter of peats is uniformly analogous to 
 that of the stratum on which they repose ; the plants 
 which have formed them must have derived the earths 
 that they contained from this stratum. Thus in Wilt- 
 shire and Berkshire, where the stratum below the peat 
 is chalk, calcareous earth abounds in the ashes, and ve-. 
 ry little alumina or silica. They likewise contain much 
 oxide of iron and gypsum, ])oth of which may be deri- 
 ved from the decomposition of the pyrites, so abundant 
 in chalk. 
 
 Different specimens of peat that I have burnt from 
 the granitic and schistose soils of different parts of these 
 islands, have always given ashes principally siliceous 
 and aluminous ; and a specimen of peat from the coun- 
 ty of Antrim, gave ashes which afforded very nearly 
 tlie same constituents as the great basaltic stratum of the 
 county. 
 
 Poor and hungry soils, such as are produced frOm the 
 decomposition of granitic and sandstone rocks, remain 
 very often for ages with only a thin covering of vegeta- 
 
134 
 
 tioii. Soils from the decomposition of limestone, chalks, 
 and basaltsj are often clothed by nature with the peren- 
 nial grasses ; and afford, when ploughed up, a rich bed 
 of vegetation for every species of cultivated plant. 
 
 Hocks and strata from which soils have been derived, 
 and those which compose the more interior solid parts 
 of the globe, are arranged in a certain order ; and as it 
 often happens that strata very different in their nature 
 are associated together, and that the strata immediately 
 beneath the soil contain materials which may be of use 
 for improving it, a general view of the nature and posi- 
 tion of rocks and strata in nature, will not, I trust, be 
 unacceptable to the scientific farmer. 
 
 Kocks are generally divided by geologists into two 
 grand division's, distinguished by the names of primary 
 and secondary. 
 
 The primary rocks are composed of pure crystalline 
 matter, and contain no fragments of other rocks. 
 
 The secondary rocks, or strata, consist only partly of 
 crystalline matter ; contain fragments of other rocks or 
 strata ; often abound in the remains of vegetables and 
 marine animals ; and sometimes contain the remains of 
 land animals. 
 
 The primary rocks are generally arranged in large 
 masses, or in layers vertical, or more or less inclined to 
 the horizon. 
 
 The secondary rocks are usually disposed in strata 
 or layers, parallel, or nearly parallel to the horizon. 
 
 The number of primary rocks which are commonly 
 observed in nature are eight. 
 
 First, granite, which as has been mentioned, is compo- 
 sed of quartz, feldspar, and mica; when these bodies are 
 arranged in regular layers in the rock, it is called gneis. 
 
 Second, micaceous schistiiSf which is composed of 
 quartz and mica arranged in layers, which are usually 
 curvilineal. 
 
 Third, sienite, which consists of the substance called 
 hornblende and feldspar. 
 
 Fourth, serpentine, which is constituted by feldspar 
 and a body named resplendent hornblende ; and their 
 separate crystals are often so small as to give the stone 
 a uniform appearance : this rock abounds in veins of a 
 substance called steatite, or soap rock. 
 
135 
 
 Fifth, porphyry f which consists of crystals of feldspai' 
 embedded in the same material, but usually of a difl'er- 
 ent colour. 
 
 Sixth, graiiular marble, which consists entirely of 
 crystals of carbonate of lime ; and which, when its co- 
 lour is white, and texture fine, is the substance used by 
 statuaries. 
 
 Seventh, chlorite schist, which consists of chlorite, a 
 green of gray substance somewhat analogous to mica 
 and feldspar. 
 
 Eight, qiiartzose rock, which is composed of quartz 
 in a granular form sometimes united to small quantities 
 of the crystalline elements, which have been mentioned 
 as belonging to the other rocks. 
 
 The secondary rocks are more numerous than the pri- 
 mary ; but twelve varieties include all that are usually, 
 found in these islands. 
 
 First, graiiwacke, which consists of fragments of 
 quartz, or chlorite schist, embedded in a cement, prin- 
 cipally composed of feldspar. 
 
 Second, siliceous sandstone, which is composed of 
 fine quartz or sand, united by a siliceous cement. 
 
 Third, limestone, consisting of carbonate of lime, 
 more compact in its texture than in the granular mar- 
 ble ; and often abounding in marine exuvia. 
 
 Fourth, aluminous schist or shale, consisting of the 
 decomposed materials of diflFerent rocks cemented by a 
 small quantity of ferruginous or siliceous matter ; and 
 often containing the impressions of vegetables. 
 
 Fifth, calcareous sandstone, which is calcareous sand, 
 cemented by calcareous matter. 
 
 Sixth, iron stone, formed of nearly the same mate- 
 rials as aluminous schist, or shale ; but containing a 
 much larger quantity of oxide of iron. 
 
 Seventh, basalt or whinstone, which consists of feld- 
 spar and hornblende, with materials derived from the 
 decomposition of the primary rocks ; the crystals are 
 generally so small as to give the rock a homogeneous 
 appearance ; and it is often disposed in very regular 
 columns, having usually five or six sides. 
 Eighth, bituminous or common coal. 
 Ninth, gypsum^ the substance so well known by that 
 
136 
 
 name, which consists of sulphate of lime ; and often 
 contains sand. 
 
 Tenth, rock salt. 
 
 Eleventh, vhalk, whicli usually abounds in remains of 
 marine animals, and contains horizontal layers of flints. 
 
 Twelfth plum-pudding stone, consisting of pebbles 
 cemented by a ferruginous or siliceous cement. 
 
 To describe more particularly the constituent parts of 
 the difl'erent rocks and strata will be unnecessary : at 
 any time, indeed, details on this subject are useless, un- 
 less the specimens are examined bythe!eye; and a close 
 inspection and comparison of the different species, will, 
 in a short time, enable the most common observer to dis- 
 tinguish them. 
 
 Tlie highest mountains in these islands, and indeed 
 in the whole of the old continent, are constituted by 
 granite ; and this rock has likewise been found at the 
 greatest depths to which the industry of man has as yet 
 been able to penetrate ; micaceous schist is often found 
 immediately upon granite ; serpentine or marble upon 
 micaceous schist : but the order in which the primary 
 rocks are grouped together is various. Marble and 
 serpentine are usually found uppermost; but granite, 
 though it seems to form the foundation of the rocky 
 strata of the globe, is yet sometimes discovered above 
 micaceous schist. 
 
 Tlie secondary rocks are always incumbent on the 
 primary ; the lowest of them is usually grauwacke : 
 upon this, limestone or sandstone is often found ; coal 
 generally occurs between sandstone or shale ; basalt of- 
 ten exists above sandstone and limestone ; rock salt al- 
 most always occurs associated with red sandstone and 
 gypsum. Coal,' basalt, sandstone and limestone, are 
 often arranged in different alternate layers, of no con- 
 siderable thickness, so as to form a great extent of coun- 
 try. In a depth of less than 500 yards, 80 of these 
 different alternate strata have been counted. 
 
 The veins which afford metallic substances, are fis- 
 sures more or less vertical, filled with a material differ- 
 ent from the rock in which they exist. 'Jliis material 
 is almost always crystalline ; and usually consists of 
 calcareous spar, ttuor spar, quartz, or heavy spar either 
 
137 
 
 separate or together. The metallic substances are ge- 
 nerally dispersed through, or confusedly mixed with 
 these crystalline bodies. The veins in hard granite sel- 
 dom afford much useful metal ; but in the veins in soft 
 granite, and in gneis, tin, copper, and lead are found. 
 Copper and iron are the only metals usually found in 
 the veins in serpentine. Micaceous schist, sienite, and 
 granular^marble, are seldom metalliferous rocks. Lead, 
 tin, copper, iron, and many otlier metals are found in 
 the veins in chlorite schist. Grauwacke, when it con- 
 tains few fragments and exists in large masses, is often 
 a metalliferous rock. The precious metals, likewise 
 iron, lead, and antimony, are found in it ; and sometimes 
 it contains veins or masses of stone coal, or coal free 
 from bitumen. Limestone is the great metalliferous rock 
 of the secondary family ; and lead and copper are the 
 metals most usually found in it. No metallic veins 
 have ever been found in shale, chalk or calcareous sand- 
 stone; and they are very rare in basalt and silicious 
 sandstone.* 
 
 In cases where veins in rocks are exposed to the at- 
 mosphere, indications of the metals they contain may be 
 often gained from their superficial appearance. When- 
 ever iluor' spar is found in a vein, there is always strong 
 reason to suspect that it is associated with metallic sub- 
 stances. A brown powder at the surface of a vein al- 
 ways indicates iron, and often tin ; a pale yellow pow- 
 der lead ; and a green colour in a vein denotes the pre- 
 sence of copper. 
 
 It may not be improper to give a general description 
 of the geological constitution of Great Britain and L'e- 
 land. Granite forms the great ridge of hills extending 
 from Land's End through Dartmoor into Devonshire. 
 The highest rocky strata in Somersetshire are grau- 
 wacke and limestone. The Malvern hills are compo- 
 sed of granite sienate and porphyry. The highest moun- 
 tains in Wales are chlorite schist, or grauwacke. Gra- 
 nite occurs at Mount Sorrel in Leicestershire. The 
 great range of the mountains in Cumberland and West- 
 
 * Fig. 1 6, will give a general idea of the appearance and arrange- 
 ment of rocks and veins. 
 
LSS 
 
 niorelniiil. ;uc poiphyvy, chlorite, schist, and grauwacke; 
 but iijranUc is tVmiul at the western boundary. Through- 
 out Scotland tlie most elevated rocks are granite, sienite, 
 and micaceous scliistus. No true secondary formations 
 are found in South Britain, west of Dartmoor ; and no 
 basalt south of the Severn. The chalk district extends 
 from the western part of Dorsetshire, to the eastern coast 
 of Norfolk. The coal formations abound in the district 
 between Glamorganshire and Derbyshire; and likewise 
 in the secondary strata of Yorkshire, Durham, West- 
 moreland, and Northumberland. Serpentine is found 
 only in three places in Great Britain ; near Cape Li- 
 zard in Cornwall, Portsoy in Aberdeenshire, and in 
 Ayrshire. Black and gray granular marble is found 
 near Padstow in Cornwall ; and other coloured prima- 
 ry marbles exist in the neighbourhood of Plymouth. 
 Coloured primary marbles are abundant in Scotland ; 
 and white granular marble is found in the Isle of Sky, 
 in Assynt, and on the banks of Loch Shin in Suther- 
 land : the principal coal formations in Scotland, are in 
 Dumbartonshire, Ayrshire, Fifeshire, and on the banks 
 of the Brora in Sutherland. Secondary limestone and 
 sandstone are found in most of the low countries north 
 of the Mendip hills. 
 
 In Ireland there are five great associations of prima- 
 ry mountains ; the mountains of Morne in the county of 
 Down; the mountains of Donegal; those of Mayo and 
 Galway, those of Wicklow, and those of Kerry. The 
 rocks composing the four first of these mountain chains 
 are principally granite, gneis, sienite, micaceous schist, 
 and porphyry. The mountains of Kerry are chiefly 
 constituted by granular quartz, and chlorite schist. Co- 
 loured marble is found near Killarney; and white mar- 
 ble on the western coast of Donegal. 
 
 Limestone and Sandstone are the common secondary 
 rocks found south of Dublin. In Sligo, Roscommon, 
 and Leitrim, limestone, sandstone, shale, iron stone, and 
 bituminous coal are found. The secondary hills in these 
 counties are of considerable elevation ; and many of them 
 have basaltic summits. The northern coast of Ireland 
 is principally basalt ; this rock commonly reposes upon 
 a white limestone, containing layers of flint, and the 
 same fossils as chalk ; but it is considerably harder than 
 
139 
 
 that rock. There are some instances, in this district, 
 in which columnar basalt is found above sandstone and 
 shale, alternating with coal. The stone coal of Ireland 
 is principally found in Kilkenny, associated with lime- 
 stone and grauwacke. 
 
 It is evident from what has been said concerning the 
 production of soils from rocks, that there must be at least 
 as many varieties of soils as there are species of rocks 
 exposed at the surface of the earth ; in fact there are 
 many more. Independent of the changes produced by 
 cultivation and the exertions of human labour, the ma- 
 terials of strata have been mixed together and transport- 
 ed from place to place by various great alterations that 
 have taken place in the system of our globe, and by the 
 constant operation of water. 
 
 To attempt to cla's"? soils with scientific accuracy would 
 be a vain labour; the distinctions adopted by farmers are 
 sufficient for the purposes of agriculture ; particularly if 
 some degree of precision be adopted in the application 
 of terms. The term sandy, for instance, should never 
 be applied to any soil that does not contain at least se- 
 ven-eighths of sand ; sandy soils that eifervesce with 
 acids should be distinguished by the name of calcareous 
 sandy soil, to distinguish them from those that are sili- 
 ceous. The term clayey soil should not be applied to 
 any land which contains less than one-sixth of impalpa- 
 ble earthy matter, not considerably effervescing with 
 acids ; the word loam should be limited to soils, contain- 
 ing at least one-third of impalpable earthy matter, copi- 
 ously effervescing with acids. A soil to be considered 
 as peaty, ought to contain at least one-half of vegetable 
 matter. 
 
 In cases where the earthy part of a soil evidently con- 
 sists of the decomposed matter of one particular rock, a 
 name derived from the rock may with propriety be ap- 
 plied to it. Thus, if a fine red earth be found imme- 
 diately above decomposing basalt, it may be denomina- 
 ted basaltic soil. If fragments of quartz and mica be 
 found abundant in the materials of the soil, which is 
 often the case, it may be denominated granitic soil ; and 
 the same principles may be applied to other like in- 
 stances. 
 
 In general, the ^oils, the materials of which are the 
 
t40 
 
 most various iiud hetevogeueous, are those called alluvi- 
 al, or which have been formed from the depositions of 
 rivers ; many of tliem are extremely fertile. 1 have ex- 
 amined some productive alluvial soils, which have been 
 very different in their composition. The soil which has 
 been mentioned pai;e 128, as very productive, from the 
 banks of tlie river Parret in Somersetshire, afforded me 
 eight parts of finely divided earthy matter, and one part 
 of siliceous sand ; and an analysis of the finely divided 
 matter gave the following results. 
 
 360 parts of carbonate of linie. 
 
 25 alumina. 
 
 20 silica. 
 
 8 oxide of iron.^ 
 
 19 vej^etable, animal, and saline mat- 
 ter. 
 
 A rich soil from the neighbourhood of the Avon in the 
 valley of Evesham in Worcestershire, afforded me three- 
 fifths of fine sand, and two-fifths of impalpable matter ; 
 the impalpable matter consisted of 
 
 35 Alumina. 
 
 41 Silica. 
 
 14 Carbonate of lime. 
 
 3 Oxide of iron. 
 
 7 Vegetable, animal, and saline matter. 
 
 A specimen of good soil from Tiviot-dale, afforded 
 five-sixths of fine siliceous sand, and one-sixth of im- 
 palpable matter which consisted of 
 
 41 Alumina. 
 
 42 Silica. 
 
 4 Carbonate of lime. 
 
 5 Oxide of iron. 
 
 8 Vegetable, animal, and saline matter. 
 
 A soil yielding excellent pasture from the valley of 
 the Avon, near Salisbury, afforded one- eleventh of coarse 
 siliceous sand; and the finely divided matter consisted 
 of 
 
141 
 
 7 Alumina. 
 14 Silica. 
 
 63 Carbonate of lime. 
 2 Oxide of iron. 
 ^ 14 Vegetable, animal, and saline matter. 
 
 In all these instances the fertility seems to depend 
 upon the state of division, and mixture of the earthy 
 materials and the vegetable and animal matter ; and 
 may be easily explained on the principles which 1 have 
 endeavoured to elucidate in the preceding part of this 
 Lecture. 
 
 In ascertaining the composition of sterile soils with a 
 view to their improvement, any particular ingredient 
 which is the cause of their unproductiveness, should 
 be particularly attended to; if possible, they should be 
 compared with fertile soils in the same neighbourhood, 
 and in similar situations, as the difference of the com- 
 position may, in many cases, indicate the most proper 
 methods of improvement. If on washa sterile soil it 
 is found to contain the salts of iron, or any acid 
 matter, it may be ameliorated by the application of 
 quick lime. A soil of good apparent texture from 
 Lincolnshire, was put into my hands by Sir Joseph 
 Banks as remarkable for sterility : on examining it, I 
 found that it contained sulphate of iron ; and I offer- 
 ed the obvious remedy of top dressing with lime, which 
 converts the sulphate into a manure. If there be an 
 excess of calcareous matter in the soil, it may be im- 
 proved by the application of sand, or clay. Soils too 
 abundant in sand are benefited by the use of clay, or 
 marie, or vegetable matter. A field belonging to Sir 
 Robert Vaughan at Nannau, Merionethshire, the soil of 
 which was a light sand, was much burnt up in the sum- 
 mer of 1805 ; I recommended to that gentleman the ap- 
 plication of peat as a top dressiiig. The experiment 
 was attended with immediate good effects ; and Sir Ro- 
 bert last year informed me, that the benefit was perma- 
 nent. A deficiency of vegetable or animal matter must 
 be supplied by manure. An excess of vegetable mat- 
 ter is to be removed by burning, or to be remedied by 
 the application of earthy materials. The improvement 
 
142 
 
 or peats, ov bogs, ov marsli land^, must be i)icce(ie(l by 
 draiiiiiij;" ; sta^^iiaut water beiiij; injurious to all the nu- 
 tritive classes of plants. Hoft black peats, when drain- 
 ed, are often made productive by the mere application 
 of sand or clay as a top dressing;. When peats arc 
 acicl, or contain ferrujijinous salts, calcareous matter is 
 absolutuely necessary in brini^iiii;; them into cultivation. 
 When they abiuind in the l>ranches and roots of trees, 
 or when their surface entirely consists of living vegeta- 
 bles, the wood or the vegetables must either be carried 
 off, or }>e destroyed by burning. In the last case their 
 ashes allcu'd eartiiy ingredients, fitted to improve the tex- 
 ture of the peat. 
 
 The best natural soils are those of which the materi- 
 als have been derived from difl'erent strata; which have 
 been minutely »livitle»l by air and water, and arc inti- 
 mately blended together : and in improving soils artifi- 
 cially, the farmer ( annot do better than imitate the pro- 
 cesses of nature. 
 
 The materials necessary for the purpose are seldom 
 far distant : coarse sand is often found immediately on 
 chalk ; and beds (»f sand and gravel are common below 
 clay. The labour of improving the texture or constitu- 
 tion of the soil, is repaid l)y a great permanent advan- 
 tage ; less manure is required, and its fertility insured : 
 ami capital laid out in this way secures for ever, the pro- 
 ductiveness, and consequently the value of the land. 
 
LECTURE V. 
 
 On the J\rature and Constittition of the Atmosphere ; and 
 its Influence on Vegetables. Of the Germination of 
 Seeds. Of the Functions of IHants in their differ - 
 ent Stages of Growth ; with a general View of the 
 Progress of Vegetation. 
 
 L HE constitution of the atmosphere has heen already 
 generally referred to in tlic preceding Lectures. Water, 
 carbonic acid gas, oxygene, and azote, have been men- 
 tioned as the principal substances composing it ; but more 
 minute inquiries respecting tlieir nature and agencies are 
 necessary to afford correct views of the uses of the at- 
 mosphere in vegetation. 
 
 On tliese inquiries 1 now propose to enter ; the pur- 
 suit of them, 1 hope, will offer some objects of practical 
 use in farming ; and present some philosophical illustra- 
 tions of the manner in which plants are nourished; their 
 organs unfolded, and their functions developed. 
 
 If some of the salt called muriate of lime that has 
 been just heated red be exposed to the air, even in the 
 driest and coldest weather, it will increase in weight 
 and become moist ; and in a certain time will be con- 
 verted into a fluid. If put into a retort and heated, it 
 will yield pure water ; will gradually recover its pris- 
 tine state ; and, if heated red, its former weight : so that 
 it is evident, that the water united to it was derived from 
 the air. And that it existed in the air in an invisible 
 and elastic form, is proved by the circumstance, that if 
 a given quantity of air be exposed to the salt, its volume 
 and weight will diminish, provided the experiment be 
 correctly made. 
 
 The quantity of water which exists in air, as vapour, 
 varies with the temperature. In proportion as the wea- 
 ther is hotter, the quantity is greater. At 50" of Fah- 
 renheit air contains about one fiftieth of its volume of 
 vapour 5 and as the specific gravity of vajiour is to that 
 
144 
 
 of air nearly as 10 to 15, this is about one-seventy-fiftli 
 of its weight. 
 
 At 100°, supposing that there is a free communica- 
 tion with water, it contains about one fourteenth parts 
 in volume, or one- twenty-first in weight. It is the con- 
 densation of vapour by diminution of the temperature 
 of the atmosphere, which is probably the principal cause 
 of the formation of clouds, and of the deposition of dew, 
 mist, snow, or hail. 
 
 The power of different substances to absorb aqueous 
 vapour from the atmosphere by cohesive attraction was 
 discussed in the last Lecture. The leaves of living 
 plants appear to act upon the vapour likewise in its elas- 
 tic form, and to absorb it. Some vegetables increase in 
 Aveight from this cause, when suspended in the atmos- 
 phere and unconnected with the soil ; such are the house- 
 leek, and different species of the aloe. In very intense 
 heats, and when the soil is dry, the life of plants seems 
 to be preserved by the absorbent power of their leaves : 
 and it is a beautiful circumstance in the economy of na- 
 ture, that aqueous vapour is most abundant in the at- 
 mosphere when it is most needed for the purposes of life ; 
 and that when other sources of its supply are cut off, 
 this is most copious. 
 
 The compound nature of water has been referred to. 
 It may be proper to mention the experimental proofs of 
 its decomposition into, and composition from, oxygene 
 and hydrogene. 
 
 If the metal called potassium be exposed in a glass 
 tube to a small quantity of water, it will act upon it 
 with great violence ; elastic fluid will be disengaged, 
 which will be found to be hydrogene ; and the same ef- 
 fects will be produced upon the potassium, as if it had 
 absorbed a small quantity of oxygene ; and the hydro- 
 gene disengaged, and the oxygene added to the potas- 
 sium are in weight as two to 15 ; and if two in volume 
 of hydrogene, and one in volume of oxygene, which have 
 the weights of two and 15, be introduced into a close 
 vessel, and an electrical spark passed through them, 
 they will inflame and condense into 17 parts of pure 
 water. 
 
 It is evident from the statements given in the third 
 
145 
 
 Lecture, that water forms by far the greatest part of the 
 sap of plants ; and that this substance, or its elements, 
 enters largely into the constitution of their organs and 
 solid productions. 
 
 Water is absolutely necessary to the economy of ve- 
 getation in its elastic and fluid state ; and it is not de- 
 void of use even in its solid form. Snow and ice are 
 bad conductors of heat ; and when the ground is cover- 
 ed with snow, or the surface of the soil or of water is 
 frozen, the roots or bulbs of tlic plants beneath are pro- 
 tected by the congealed water from the influence of the 
 atmosphere, the temperature of which in northern win- 
 ters is usually very much below the freezing point ; and 
 this water becomes the first nourishment of the plant in 
 early spring. The expansion of water during its con- 
 gelation, at which time its volume increases one-twelfth, 
 and its contraction of bulk during a thaw, tend to pul- 
 verise the soil ; to separate its parts from eacli other, 
 and to made it more permeable to the influence of the air. 
 
 If a solution of lime in water be exposed to the air, 
 a pellicle will speedily form upon it, and a solid matter 
 will gradually fall to the bottom of the water, and in a 
 certain time the water will become tasteless ; this is ow- 
 ing to the combination of the lime, which was dissol- 
 ved in the water, with carbonic acid gas which existed 
 in the atmosphere, as may be proved by collecting the 
 film and the solid matter, and igniting them strongly in 
 a little tube of platina or iron ; they will give off car- 
 bonic acid gas, and will become quicklime, which add- 
 ed to the same water, will again bring it to the state of 
 lime water. 
 
 The quantity of carbonic acid gas in the atmosphere 
 is very small. It is not easy to determine it with pre- 
 cision, and it must differ in different situations ; but 
 where there is a free circulation of air, it is probably 
 never more than one-five hundredth, nor less than one- 
 eight hundredtli of the volume of air. Carbonic acid 
 gas is nearly one-third heavier than the other elastic 
 parts of the atmosphere in their mixed state : hence at 
 first view it might be supposed tiiat it would be most 
 abundant in the lower regions of the atmosphere ; but 
 unless it has been immediately produced at the surface 
 
146 
 
 of the earth ill some chemical process, this does not 
 seem to he the case : elastic iluids of different speciiic 
 gravities have a tendency to equahle mixture by a spe- 
 cies of attraction, and the different parts of the atmos- 
 phere are constantly agitated and blended together by 
 winds or other causes. . I)e Saussure found lime water 
 precipitated on Mount Blanc, the highest point of land 
 in Europe ; and carbonic acid gas has been "always 
 found, apparently in due proportion, in the air brought 
 down from great heights in the atmosphere by aerostatic 
 adventurers. 
 
 The experimental proofs of the composition of car- 
 bonic acid gas are very simple. If 13 grains of well 
 burnt charcoal be inflamed by a burning-glass in 100 
 cubical inches of oxygene gas, the charcoal will entirely 
 disappear : and provided the experiment be correctly 
 made, all the oxygene except a few cubical inches, will 
 be found converted into carbonic acid ; and what is very 
 remarkable, the volume of the gas is not changed. On 
 this last circumstance it is easy to found a correct esti- 
 mation of the quantity of pure charcoal and oxygene 
 in carbonic acid gas : the weight of 100 cubical inches 
 is to that of 100 cubical inches of oxygene gas, as 47 
 to 34 : so that 47 parts in weight of carbonic acid gas, 
 must be composed of 34 parts of oxygene and, 13 of 
 charcoal, which correspond with the numbers given in 
 the second Lecture. 
 
 Carbonic acid is easily decomposed, by heating potas- 
 sium in it ; the metal combines with the oxygene, and 
 the charcoal is deposited in the form of a black powder. 
 
 The principal consumption of the carbonic acid in 
 the atmosphere, seems to be in affording nourishment 
 to plants ; and some of them appear to be supplied with 
 carbon chiefly from this source. 
 
 Carbonic acid gas is formed during fermentation, com- 
 bustion, putrefaction, respiration, and a number of ope- 
 rations taking place upon the surface of the earth ; and 
 there is no other process known in nature by which it 
 can be destroyed but by vegetation. 
 
 After a given portion of air has been deprived of 
 aqueous vapour and carbonic acid gas, it appears little 
 altered in its properties: it suppoi-ts combustion and an i- 
 
147 
 
 wal life. There are many ijiodes of separating its prin- 
 cipal constituents, oxygene and azote, from each other. 
 A simple one is by burning phosphorus in a confined 
 volume of air : this absorbs the oxygene and leaves the 
 azote; and 100 parts in volume of air, in which phos- 
 phorus has been burnt, yield 79 parts of azote : and by 
 mixing this azote with 21 parts of fresh oxygene gas 
 artificially procured, a substance having the original 
 characters of air is produced. To procure pure oxy- 
 gene from air, quicksilver may be kept heated in it, at 
 about 600°, till it becomes a red powder ; this powder, 
 when ignited, will be restored to the state of quicksilver 
 by giving off oxygene. 
 
 Oxygene is necessary to some functions of vegeta- 
 bles ; but its great importance in nature is in its relation 
 to the economy of animals. It is absolutely necessary 
 to their life. Atmospheric air taken into the lungs of 
 animals, or passed 4n solution in water through the gills 
 of fishes, loses oxygene ; and for the oxygene lost, about 
 an equal volume of carbonic acid appears. 
 
 The effects of azote in vegetation are not distinctly 
 known. As it is found in some of the products of ve- 
 getation, it may be absorbed by certain plants from the 
 atmosphere. It prevents the action of oxygene from 
 being too energetic, and serves as a medium in which 
 the more essential parts of the air act ; nor is this cir- 
 cumstance unconformable to the analogy of nature; for 
 the elements most abundant on the solid surface of the 
 globe, are not those which are the most essential to th& 
 existence of the living beings belonging to it. 
 
 The action of the atmosphere on plants differs at dif- 
 ferent periods of their growth, and varies with the va- 
 rious stages of the development and decay of their or- 
 gans ; some general idea of its influence may have been 
 gained from circumstances already mentioned ; I shall 
 now refer to it more particularly, and endeavour to 
 connect it with a general view of the progress of vege- 
 tation. 
 
 If a healthy seed be moistened and exposed to air at 
 a temperature not below 45°, it soon germinates; it 
 shoots forth a plume which rises upwards^ and a raiU- 
 cle which descends* 
 
14B 
 
 If the ai? be confined, it is found that in the process 
 of germination the oxygene, or a part of it is absorbed. 
 The azote remains unaltered ; no carbonic acid is ta- 
 ken away from tlie air, on the contrary some is added. 
 
 Seeds are incapable of germinating, except when oxy- 
 gcne is present. In tlie exhausted receiver of the air- 
 pump, in pure azote, in pure carbonic acid, when mois- 
 tened they swell, but do not vegetate : and if kept in 
 these gases, lose their living powers and undergo putre- 
 faction. 
 
 If a seed be examined before germination, it will be 
 found more or less insipid, at least not sweet ; but af- 
 ter germination it is always sweet. Its coagulated mu- 
 cilage, or starcli, is converted into sugar in the process ; 
 a substance difficult of solution is changed into one easily 
 soluble : and the sugar carried through the cells or ves- 
 sels of the cotyledons, is the nourishment of the infant 
 plant. It is easy to understand the nature of the change, 
 by referring to the facts mentioned in the third Lecture ; 
 and the production of carbonic acid renders probable 
 the idea, that the principal chemical difference between 
 sugar and mucilage depends upon a slight difference in 
 the proportions of their carbon. 
 
 The absorption of oxygene by the seed in germina- 
 tion, has been compared to its absorption in producing 
 the evolution of foetal life in the egg : but this analogy 
 is only remote. All animals, from the most to the least 
 perfect classes, require a supply of oxygene.* From 
 
 * The impregnated egs^s of insects, and even fishes, do not pro- 
 duce younpj ones, unless they are supplied with air, that is, unless 
 the foetus can respire. I have found that the eggs of moihs did not 
 produce larva: when confined in pure carbonic acid ; and when they 
 were exposed in common air, the oxygene partly disappeared, and 
 carbonic acid was formed. The fish in the egg or spawn, gains its 
 oxygene from the air dissolved in water; and those fishes that spawn 
 in spring and summer in still water, such as the pike, carp, perch, 
 and bream, deposit their eggs upon subaquatic vegetables, the leaves 
 of which, in performing their healthy functions, supply oxygene to 
 the water. Tlie fish that spawn in winter, such as the salmon and 
 trout, seek spots where there is a constant supply of fresh water, as 
 near the sources of streams as possible, and in the most ra])id cur- 
 rents, where all stagnation is prevented, and where the water is satu- 
 rated vvitii air, to which it has been exposed during its deposition 
 from clouds. It is the instinct leading these fish to seek a supply of 
 
p. 148 
 
149 
 
 llie moment the heart begins to pulsate till it ceases to 
 beat, the aeration of the blood is constant, and the func- 
 tion of respiration invariable ; carbonic acid is given off 
 in the process, but the chemical change produced in the 
 blood is unknown ; nor is the reany reason to suppose 
 the formation of any substance similar to sugar. In the , 
 production of a plant from a seed, some reservoir of 
 nourishment is needed before the root can supply sap : 
 and this reservoir is the cotyledon in which it is stored 
 up in an insoluble form, and protected if necessary du- 
 ring the winter, and rendered soluble by agents which 
 are constantly present on the surface. The change of 
 starch into sugar, connected with the absorption of oxy- 
 gene, may be rather compared to a process of fermenta- 
 tion than to that of respiration ; it is a change effected 
 upon unorganized matter, and can be artificially imita- 
 ted ; and in most of the chemical changes that occur 
 when vegetable compounds are exposed to air, oxygene 
 is absorbed, and carbonic acid formed or evolved. 
 
 It is evident, that in all cases of tillage the seeds should 
 be sown so as to be fully exposed to the influence of the 
 air. And one cause of the unproductiveness of cold 
 clayey adhesive soils is, that the seed is coated with 
 matter impermeable to air. 
 
 In sandy soils the earth is always sufficiently pene- 
 trable by the atmosphere ; but in clayey soils there can 
 scarcely be too great a mechanical division of parts in 
 the process of tillage. Any seed not fully supplied with 
 air, always produces a weak and diseased plant. 
 
 The process of malting which has been already refer- 
 red to, is merely a process in which germination is ar- 
 tificially produced; and in which the starch of the coty- 
 ledon is changed into sugar; which sugar is afterwards, 
 by fermentation, converted into spirit. 
 
 It is very evident from the chemical principles of ger- 
 mination, that the process of malting should be carried 
 on no farther than to produce the sprouting of the radi- 
 cle, and should be checked as soon as this has made its 
 distinct appearance. If it is pushed to such a degree as 
 
 air for their eggs which carries them from seas, or hikes into the 
 niountuin country ; which induces them to move against ilie streauj, 
 and to endeavour to overleap weirs, mill-dams, and calarat (s. 
 
15.0 
 
 to occasion the perfect developenient of the radicle and 
 the plume, a considerable quantity of saccharine matter 
 will have been consumed in producing their expansion, 
 and there will be less spirit formed in fermentation, or 
 produced in distillation. 
 
 As this circumstance is of some importance, I made 
 in October 1806, an experiment relating to it. I ascer- 
 tained by the action of alcohol, the relative proportions 
 of saccharine matter in two equal quantities of the same 
 barley ; in one of which the germination had proceeded 
 so far as to occasion protrusion of the radicle to nearly 
 a quarter of an inch beyond the grain in most of the 
 specimens, and in the other of which it had been check- 
 ed before the radicle was a line in length ; the quantity 
 of sugar afforded by the last was to that in the first near- 
 ly as six to five. 
 
 The saccharine matter in the cotyledons at the time 
 of their change into seed-leaves, renders them exceed- 
 ingly liable to the attacks of insects : this principle is at 
 once a nourishment of plants and animals, and the great- 
 est ravages are committed upon crops in this first stage 
 of their growth. 
 
 The turnip fly, an insect of the colyoptera gfiinus, fixes 
 itself upon the seed-leaves of the turnip at the time that 
 they are beginning to perform their functions : and when 
 the rough leaves of the plume are thrown forth, it is in- 
 capable of injuring the plant to any extent. 
 
 Several methods have been proposed for destroying 
 the turnip fly, or for preventing it from injuring th6 crop. 
 It has been proposed to sow radish-seed with the tur- 
 nip-seed, on the idea that the insect is fonder of the 
 seed leaves of the radish than those of the turnip ; it is 
 said that this plan has not been successful, and that the 
 fly feeds indiscriminately on both. 
 
 There are several chemical menstrua which render the 
 process of germination much more rapid, when the seeds 
 have been steeped in them. As in these cases the seed- 
 leaves are quickly produced, and more speedily perform 
 their functions, I proposed it as a subject of experiment 
 to examine whether such menstrua might not be useful 
 in raising the turnip more speedily to that state in 
 which it would be secure from the fly ; but the result 
 
151 
 
 proved tliat the practice was inadmissible; for seeds so 
 treated, though they germinated much quicker, did not 
 produce healthy plants, and often died soon after sprout- 
 ing. 
 
 I steeped radish seeds in September 1807, for twelve 
 hours, in a solution of chlorine, and similar seeds in ve- 
 ry diluted nitric acid, in very diluted sulphuric acid, in 
 weak solution of oxysulphate of iron, and some in com- 
 mon water. The seeds in solutions of chlorine and 
 oxysulphate of iron, threw out the germ in two days ; 
 those in nitric acid in three days, in sulphuric acid in 
 five, and those in water in seven days. But in the 
 cases of premature germination, though the plume was 
 very vigorous for a short time, yet it became at the end 
 of a fortnight weak and sickly ; and at that period less 
 vigorous in its growth than the sprouts which had been 
 naturally developed, so that there can be scarcely any 
 useful application of these experiments. Too rapid 
 growth and premature decay seem invariably connected 
 in organized structures ; and it is only by following the 
 slow operations of natural causes, that we are capable 
 of making improvements. 
 
 There is a number ef chemical substances which are 
 very oflFensive and even deadly to insects, which do not 
 injure, and some of which even assist vegetation. Se- 
 veral of these mixtures have been tried with various suc- 
 cess ; a mixture of sulphur and lime, which is very de- 
 structive to slugs, does not prevent the ravages of the 
 fly on the young turnip crop. His Grace the Duke of 
 Bedford, at my suggestion, was so good as to order the 
 experiment to be tried on a considerable scale at Wo- 
 burn farm : the mixture of lime and sulphur was strew- 
 ed over one part of the field sown with turnips ; nothing 
 was applied to the otlrer part, but both were attacked 
 nearly in the same manner by the fly. 
 
 Mixtures of soot and quicklime, and urine and quick- 
 lime, will probably be more efficacious. The volatile 
 alkali given off by these mixtures is offensive to insects ; 
 and they aftbrd nourishment to the plant. Mr. T. A. 
 Knight* informs me, that he has tried the method by 
 
 * IMr. Knight has been so good as to famish me with tl>e fol!o%v-- 
 ing note on this subject. 
 
152 
 
 ammoniacal fumes with success ; but more extensive iiials 
 are necessary to establish its general efficacy. It may, 
 however, be safely adopted, for if it should fail in de- 
 stroying the fly, it would at least be a useful manure to 
 the land. 
 
 After the roots and leaves of the infant plant are form- 
 ed, the cells and tubes throughout its structure become 
 filled with fluid, which is usually supplied from the soil, 
 and the function of nourishment is performed by the ac- 
 tion of its organs upon the external elements. The con- 
 stituent parts of the air are subservient to this process ; 
 but, as it might be expected, they act differently under 
 different circumstances. 
 
 When a growing plant, the roots of which are sup- 
 
 " The experiment which I tried the year before last, and last year, 
 to preserve turnips from the fly, has not been sufficiently often re- 
 peated to enable me to speak with any degree of decision ; and last 
 year all my turnips succeeded perfectly well. In consequence of 
 your suggestion, when I had the pleasure to meet you some years 
 ago at Holkham, that lime slacked with urine might possibly be 
 found to kill, or drive off, the insects from a turnip crop, I tried that 
 preparation in mixture with three parts of soot, which was put into 
 a small barrel, with gimblet holes round it, to permit a certain quan- 
 tity of the composition, about four bushels to an acre, to pass out, 
 and to fall into the drills with the turnip seeds. Whether it was by 
 affording highly stimulating food to the plant, or giving some flavour 
 which the flies did not like, I cannot tell ; but in the year 1811, the 
 adjoining rows were eaten away, and those to which the composition 
 was applied, as above described, were scarcely at all touched. It is 
 my intention in future to drill my crop in, first, with the composition 
 on the top of the ridge ; and then to sow at least a pound of seed, 
 broad-cast over the whole ground. The expense of this will be ve- 
 ry trifling, not more than 2s. per acre ; and the horse-hoe will instant- 
 ly sweep away all the supernumeraries between the rows, should 
 those escape the flies, to which however they will be chiefly attract- 
 ed; because it will always be found that these insects prefer turnips 
 gixjwing in poor, to those in rich ground. One advantage seems to 
 be the acceleration given to the growth of the plants, by the highly 
 stimulative effects of the food they instantly receive as soon as their 
 growth commences, and long before their radicles have reached the 
 dung. The directions above given apply only to turnips sowed \ipon 
 ridges, with the manure immediately under them ; and I am quite 
 certain, that in all soils turnips should be thus cultivated. The close 
 vicinity of the manure, and the consequent short time required to 
 carry the food into the leaf, and return the organizable matter to the 
 roots, arc, in my hypothesis, points of vast importance ; and the re- 
 sults in practice are correspondent." 
 
153 
 
 plied with a proper nourishment, is exposed in the pre- 
 sence of solar light to a given quantity of atmospherical 
 air, containing its due proportion of carbonic acid, the 
 carbonic acid after a certain time is destroyed, and a 
 certain quantity of oxygene is found in its place. If 
 new quantities of carbonic acid gas be supplied, the 
 same result occurs ; so that carbon is added to plants 
 from the air by the process of vegetation in sunshine ; 
 and oxygene is added to the atmosphere. 
 
 This circumstance is proved by a number of experi- 
 ments made by Drs. Priestly, Ingenhouz and Wood- 
 house, and M- T. de Saussure ; many of which I have re- 
 peated with similar results. The absorption of carbonic 
 acid gas, and the production of oxygene are performed 
 by the leaf; and leaves recently separated from the tree 
 effect the change, when confined in portions of air con- 
 taining carbonic acid; and absorb carbonic acid and 
 produce oxygene, even wlien immersed in water hold- 
 ing carbonic acid in solution. 
 
 The carbonic acid is probably absorbed by the fluids 
 in the cells of the green or parenchymatous part of the 
 leaf; and it is from this part that oxygene gas is produ- 
 ced during the presence of light. M. Sennebier found 
 that the leaf, from which the epidermis was stripped off, 
 continued to produce oxygene when placed in water, 
 containing carbonic acid gas, and the globules of air 
 rose from the denuded parenchyma ; and it is shewn 
 both from the experiments of Sennebier and Wood- 
 house, that the leaves most abundant in parenchymatous 
 parts produce most oxygene in water impregnated with 
 carbonic acid. 
 
 Some few plants* will vegetate in an artificial atmo- 
 sphere, consisting principally of carbonic acid, and ma- 
 ny will grow for some time in air, containing from one- 
 half to one- third ; but they are not so healthy as when 
 supplied with smaller quantities of this elastic sub- 
 stance. 
 
 Plants exposed to light have been found to produce 
 oxygene gas in an elastic medium and in water, con- 
 
 * I found the Arenaria tenuifolia to produce oxygene in carbonic 
 acid, which was nearly pure. 
 
154 
 
 tahiiiie; no carbonic^ acid gas ; but in quantities much 
 smaller tlian when carbonic acid gas was present. 
 
 In the dark no oxygene gas is produced by plants, 
 whatever be tlie elastic medium to which they are expo- 
 sed ; and no carbonic acid absorbed. In most cases, on 
 the contrary, oxygene gas, if it be present, is absorbed, 
 and carbonic acid gas is produced. 
 
 In the changes that take place in the composition of 
 the organized parts, it is probable that saccharine com- 
 pounds are principally formed during the absence of 
 light; gum, Voody fibre, oils, and resins during its pre- 
 sence ; and the evolution of carbonic acid gas, or its 
 formation during the night, may be necessary to give 
 greater solubility to certain compounds in the plant. I 
 once suspected that all the carbonic acid gas produced 
 by plants in the night, or in shade, might be owing to 
 the decay of some part of the leaf, or epidermis; but the 
 recent experiments of Mr. D. Ellis are opposed to this 
 idea; and I found that a perfectly healthy plant of cele- 
 ry, placed in a given portion of air for a few hours on- 
 ly, occasioned a production of carbonic acid gas, and an 
 absorption of oxygene. 
 
 Some persons have supposed that plants exposed in 
 the free atmosphere to the vicissitudes of sunshine and 
 shade, light and darkness, consume more oxygene than 
 they produce, and that their permanent agency upon air 
 is similar to that of animals ; and this opinion is espou- 
 sed by the writer on the subject 1 have just quoted, in 
 his ingenious researches on vegetation. But all expe- 
 riments brought forwards in favour of this idea, and 
 particularly his experiments, have been made under cir- 
 cumstances unfavourable to accuracy of result. The 
 plants have been confined and supplied with food in an 
 unnatural manner; and the influence of light upon them 
 has been very much diminished by the nature of the me- 
 dia through which it passed. Plants confined in limit- 
 ed portions of atmospheric air soon become diseased ; 
 their leaves decay, and by their decomposition they ra- 
 pidly destroy the oxygene of the air. In some of the 
 early experiments of Dr. Priestly before he was ac- 
 quainted with the agency of light upon leaves, air that 
 jiad supported combustion and respiration, was found 
 
155 
 
 purified by the growth of plants when they were expo- 
 sed in it for successive days and nights ; and his expe- 
 riments are the more unexceptionable, as the plants, in 
 many of them, grew in their natural states ; and shoots, 
 or branches from them, only were introduced through 
 water in the confined atmosphere. 
 
 1 have made some few researches on this subject, and 
 I shall describe their results. On the 12th of July, 1800, 
 I placed a turf four inches square, clothed with grass, 
 principally meadow fox- tail, and white clover, in a 
 porcelain dish, standing in a shallow tray filled with 
 water ; 1 then covered it with a jar of flint glass, con- 
 taining 380 cubical inches of common air in its natural 
 state. It was exposed in a garden, so as to be liable to 
 the same changes with respect to light as in the common 
 air. On the 20th of July the results were examined. 
 There was an increase of the voKime of the gas, amount- 
 ing to fifteen cubical inches ; but the temperature had 
 changed from 64° to Tl'' ; and the pressure of the at- 
 mosphere, w^hich on the 12th had been equal to the sup- 
 port of 30.1 inches of mercury, was now equal to that 
 of 30.2. Some of the leaves of the white clover, and 
 of the fox-tail were yellow, and the whole appearance 
 of the grass less healthy than when it was first introdu- 
 ced. A cubical inch of the gas, agitated in lime-wa- 
 ter, gave a slight turbidness to the Avater ; and the ab- 
 sorption was not quite one-one hundred and fiftieth of 
 its volume. 100 parts of the residual gas exposed to a 
 solution of green sulphate of iron, impregnated with ni- 
 trous gas, a substance which rapidly absorbs oxygene 
 from air, occasioned a diminution to 80 parts. 100 parts 
 of the air of the garden occasioned a diminution to 79 
 parts. 
 
 If the results of this experiment be calculated upon 
 it, it will appear that the air had been slightly deterio- 
 rated by the action of the grasses. But the weather was 
 unusually cloudy during the progress of the experiment; 
 the plants had not been supplied in a natural manner 
 with carbonic acid gas; and the quantity formed during 
 the night, and by the action of the faded leaves, must 
 have been partly dissolved by the water ; and that this 
 "was actually the case, I proved by pouring lime-water 
 
156 
 
 into the wattr, when an immediate precipitation was oc- 
 casioned. The increase of azote 1 am inclined to attri- 
 bnte to common air disengaged from the water. 
 
 The following experiment I consider as conducted 
 under circumstances more analogous to those existing in 
 nature. A turf four inches square, from an irrigated 
 meadow, clothed with common meadow grass, meadow 
 fox-tail grass, and vernal meadow grass, was placed in 
 a porcelain dish, which swam on the surface of water 
 impregnated with carbonic acid gas. A vessel of thin 
 flint glass, of the capacity of 230 cubical inches, having 
 a funnel furnished with a stop-cock inserted in the top, 
 was made to cover the grass ; and the apparatus was ex- 
 posed in an open place; a small quantity of water was 
 daily supplied to the grass by means of the stop-cock.* 
 Every day likewise a certain quantity of water was re- 
 moved by a si[)lion, and water saturated with carbonic 
 acid gas supplied in its place ; so that it may be presu- 
 med, that a small quantity of carbonic acid gas was con- 
 stantly present in the receiver. On the 7th of July, 
 1807, the first day of the experiment, the weather was 
 cloudy in the morning, but fine in the afternoon ; the ther- 
 mometer at 67, the barometer 30.2 : towards the evening 
 of this day a slight increase of the gas was perceived, 
 the next three days were bright; but in the morning of 
 the 11th the sky was clouded; a considerable increase 
 of the volume of the gas was now observed : the 12th 
 was cloudy, with gleams of sunshine ; there was still 
 an increase, but less than in the bright days ; the 13th 
 was bright. About nine o'clock A. M. on the 14th the 
 receiver was quite full ; and considering the original 
 quantity in the jar, it must have been increased by at 
 least 30 cubical inches of elastic fluid : at times during 
 this day globules of gas escaped. At ten on the morn- 
 ing of the 15th, 1 examined a portion of the gas; it con- 
 tained less than one-fiftieth of carbonic acid gas : 100 
 parts of it exposed to the impregnated solution left only 
 75 parts ; so that the air was four per cent, purer than 
 the air of the atmosphere. 
 
 I shall detail another similar experiment made with 
 
 * See Fig. \7, 
 
157 
 
 equally decisive results. A shoot from a vine, having 
 three healthy leaves belonging to it, attached to its pa- 
 rent tree, was bent so as to be placed under the receiver 
 which bad been used in the last experiment ; the water 
 confining the common air was kept in the same manner 
 impregnated with carbonic acid gas ; the experiment was 
 carried on from August 6th, till August 14th, 1807 ; 
 during this time, though the weather had been general- 
 ly clouded, and there had been some rain, the volume 
 of elastic fluid continued to increase. Its quality was 
 examined on the morning of the 15tii ; it contained one- 
 forty- second of carbonic acid gas, and 100 parts of it 
 afforded 23.5 of oxygene gas. 
 
 These facts confirm the popular opinion, that when 
 the leaves of vegetables perform their healthy functions, 
 they tend to purify the atmosphere in the common va- 
 riations of weather, and changes from light to dark- 
 ness. 
 
 In germination, and at the time of the decay of the 
 leaf, oxygene must be absorbed ; but when it is consi- 
 dered how large a part of the surface of the earth is cloth- 
 ed with perennial grasses, and that half of the globe is 
 always exposed to the solar light, it appears by far the 
 most probable opinion, that more oxygene is produced 
 than consumed during the process of vegetation; and that it 
 is this circumstance which is the principal cause of the 
 uniformity of the constitution of the atmosphere. 
 
 Animals produce no oxygene gas during the exercise 
 of any of their functions and they are constantly con- 
 suming it; but the extent of the animal, compared to 
 that of the vegetable kingdom, is very small ; and the 
 quantity of carbonic acid gas produced in respiration, 
 and in various processes of combustion and fermenta- 
 tion, bears a proportion extremely minute to the whole 
 volume of the atmosphere : if every plant during the 
 progress of its life makes a very small addition of oxy- 
 gene to the air, and occasions a very small consumption 
 of carbonic acid, the effect may be conceived adequate 
 to the wants of nature. 
 
 It may occur as an objection to these views, that if the 
 leaves of plants purify the atmosphere, towards the, end 
 of autumn, and through the winter, and early spring, 
 
158 
 
 tlie air in our climates must become impure, the oxygeiie 
 iu it diminish, and the carbonic acid ij;as increase, which 
 is not the case ; but there is a very satisfactory answer 
 to tliis objection. The different parts of the atmosphere 
 are constantly mixed toi;ether by winds, which when 
 they are strong, move at the rate of from 60 to 100 miles 
 in an hour. In our winter, the south-west gales convey 
 air, which has been purified by the vast forests and sa- 
 vannas of Houth America, and which, passing over the 
 ocean, arrives in an uncontaminated state. The storms 
 and tempests which often occur at the beginning, and 
 towards the middle of our winter, and which generally 
 blow from the same quarter of the globe, have a salu- 
 tary influence. 15y constant agitation and motion, the 
 equilibrium of the constituent parts of the atmosphere 
 is preserved; it is fitted for the purposes of life ; and 
 those events, which the superstitious formerly referred 
 to the w rath of heaven, or the agency of evil spirits, 
 and in w hich they saw only disorder and confusion, are 
 demonstrated by science, to be ministrations of divine 
 intelligence, and connected with the order and harmony 
 of our system. 
 
 I have reasoned, in a former part of this Lecture, 
 against the close analogy which some persons have as- 
 sumed between the absorption of oxygeue and the for- 
 mation of carbonic acid gas in germination, and in the 
 respiration of the fix'tus. Similar arguments will apply 
 against the pursuit of this analogy, between the functions 
 of the leaves of the adult plant, and those of the lungs 
 of the adult animal. Plants grow vigorously only when 
 supplied Avith light ; and most species die if deprived 
 of it. It cannot be supposed that the production of 
 oxygene from the leaf, which is known to be connected 
 with its natural colour, is the exertion of a diseased 
 function, or that it can acquire carbon in the day-time, 
 when it is in most vigorous growth, when the sap is ri- 
 sing, when all its powers of obtaining nourishment are 
 exerted ; merely for the purpose of giving it off again 
 in the night, when its leaves are closed, when the motion 
 of the sap is imperfect, and when it is in a state ap- 
 proaching to that of (piiescence. Many plants that grow 
 upon rocks, or soils, containing no carbonic matter, can 
 
151^ 
 
 f)iity be supposed to acquire their charcoal from the 
 carbonic acid gas in the atmosphere ; and the leaf may 
 be considered at the same time as an organ of absorption, 
 and an organ in which the sap may undergo different 
 chemical changes. 
 
 When pure water only is absorbed ])y tlie roots of 
 plants, the fluid, in passing into tiie leaves, will proba- 
 bly have greater power to absorb carbonic acid from the 
 atmosphere. When the water is saturated with carbon- 
 ic acid gas, some of this substance, even in the sunshine, 
 may be given off by the leaves ; but a part of it like- 
 wise will be always decomposed, which has been pro- 
 ved by the experiments of M. Sennebier. 
 
 When the fluid taken up by the roots of plants con- 
 tains much carbonaceous matter, it is probable that plants 
 may give off carbonic acid from their leaves, even in 
 the sunshine. In short, the function of the leaf must 
 vary according to the composition of the sap passing 
 through it ; and according to the nature of the products 
 which are formed from it. Wlien sugar is to be pro- 
 duced, as in early spring at the time of the development 
 of buds and flowers, it is probable that less oxygene will 
 be given off, than at the time of the ripening of the seed, 
 when starch, or gums, or oils, are formed; and the pro- 
 cess of ripening the seed usually takes place when the 
 agency of the solar light is most intense. When the 
 acid juices of fruits become saccharine in the natural 
 process of vegetation, more oxygene, there is every rea- 
 son to believe, must be given off, or newly combined, 
 than at other times ; for, as it was shewn in the Third 
 Lecture, all the vegetable acids contain more oxygene 
 than sugar. It appears probable, that in some cases, in 
 which oily and resinous bodies are formed in vegetation, 
 water may be decomposed; its oxygene set free, and its 
 hydrogene absorbed. 
 
 I have already mentioned, that some plants produce 
 oxygene in pure water; Dr. Ingenhouz found this to be 
 the case with species of the confervse, I have tried 
 the leaves of many plants, particularly those tiiat pro- 
 duce volatile oils. When such leaves are exposed in 
 water saturated with oxygene gas, oxygene is given off* 
 in the solar light ; but the quantity is very small and al- 
 
160 
 
 Mays limited ; nor have I been able to ascertain with 
 certainty, whether Uie vegetative powers of the leaf were 
 concerned in tlie operation, though is seems probable. 
 I obtained a considerable quantity of oxygene in an ex- 
 periment made fifteen years ago, in which vine leaves 
 were exposed to pure water ; but on repeating tlie trial 
 often since, the quantities have always been very much 
 smaller ; I am ignorant whether this difference is owing 
 to the peculiar state of the leaves, or to some confervae 
 which might have adhered to the vessel, or to other 
 sources of fallacy. 
 
 The most important and most common products of ve- 
 getables, mucilage, starch, sugar, and woody fibre, are 
 composed of water, or the elements of water, in their 
 due proportion, and charcoal; and these, or some of 
 them, exist in all plants ; and the decomposition of car- 
 bonic acid, and the combination of water in vegetable 
 structures, are processes which must occur almost uni- 
 versally. 
 
 When glutenous and albuminous substances exist in 
 plants,* the azote they contain may be suspected to be 
 derived from the atmosphere : but no experiments have 
 been made which prove this ; they might easily be in- 
 stituted upon mushrooms and funguses. 
 
 In cases in which buds are formed, or shoots thrown 
 forth from roots, oxygene appears to be uniformly ab- 
 sorbed, as in the germination of seeds. I exposed a 
 small potato moistened with common water to 24 cubi- 
 cal inches of atmospherical air, at a temperature of 59^. 
 It began to throw forth a shoot on the third day ; when 
 it was a half au inch long I examined the air ; nearly 
 a cubical inch of oxygene was absorbed, and about tliree- 
 fourths of a cubical inch of carbonic acid formed. The 
 juices in the shoot separated from the potato, had a 
 sweet taste ; and the absorption of oxygene, and the 
 production of carbonic acid, were probably connected 
 with the conversion of a portion of starch into sugar. 
 When potatoes that have been frozen are thawed, they 
 become sweet ; probably oxygene is absorbed in this 
 process ; if so, the change may be prevented by thaw- 
 ing them out of the contact of air ; under water, for in- 
 stance, that has been recently boiled. 
 
161 
 
 In the tillering of corn, that is, the production of new 
 stalks round the original plume, there is every reason 
 to believe that oxygene must be absorbed ; for the stalk 
 at which the tillering takes place, always contains sugar, 
 and the shoots arise from a part deprived of light. The 
 drill husbandry favours this process ; for loose earth is 
 thrown by hoeing round the stalks ; they are preserved 
 from light, and yet supplied with oxygene. I have 
 counted from forty to one hundred and twenty stalks 
 produced from a grain of wheat, in a moderately good 
 crop of drilled wheat. And we are informed by Sir 
 Kenelm Digby, in 1660, that there was in the posses- 
 sion of the Fathers of the Christian Doctrine at Paris, 
 a plant of barley, which they, at that time, kept l)y them 
 as a curiosity, and which consisted of 249 stalks spring- 
 ing from one root, or grain ; and in which they counted 
 above 18,000 grains, or seeds of barley. 
 
 The great increase which takes place in the transplan- 
 tation of wheat, depends upon the circumstance, tjiat each 
 layer thrown out in tillering may be removed, and treat- 
 ed as a distinct plant. In the Philosophical Transac- 
 tions, Vol. Lviii. p. 203, the following statement may 
 be found : Mr. C. Miller, of Cambridge, sowed some 
 wheat on the 2d of June, 1766 ; and on the 8th of 
 August, a plant was taken and separated into 18 partS;, 
 and replanted ; these plants were again taken up, and 
 divided in the months of September and October, and 
 planted separately to stand the winter, which division 
 produced 67 plants. They were again taken up in 
 March and April, and produced 500 plants : the num- 
 ber of ears thus formed from one grain of wheat was 
 21,109, which gave three pecks and three quarters of 
 corn that weighed 471bs. 7ozs. ; and that were estima- 
 ted at 576,840 grains. 
 
 It is evident from the statements just given, that the 
 change which takes place in the juices of the leaf by 
 the action of the solar light, must tend to increase the 
 proportion of inflammable matter to their other consti- 
 tuent parts. And the leaves of the plants that grow in 
 darkness, or in shady places, are uniformly pale ; their 
 juices are watery and saccharine, and they do not afford 
 
 X 
 
162 
 
 oils or icsiuous substances. 1 shall detail an exp6ri- 
 ment on this suhject. 
 
 I took an equal weight, 400 grains, of the leaves of 
 two plants of endive, one bright green, which had grown 
 fully exposed to light, and the otiier almost white, which 
 had been secluded from light by being covered with a 
 box ; after being both acted upon for some time by boil- 
 ing water, in the state of pulp, the undissolved matter 
 was dried, and exposed to the action of warm alcohol. 
 The matter from the green leaves gave it a tinge of olive; 
 that from the pale leaves did not alter its colour. Scarcely 
 any s(did matter was produced by evaporation of the 
 alcohol tliat had been digested on the pale leaves : where- 
 as by the evaporation of that from the green leaves, a 
 considerable residuum was obtained : five grains of which 
 were separated from the vessel in which the evaporation 
 was carried on ; they burnt with flame, and appeared 
 partly matter analogous to resin. 53 grains of woody 
 fibre were obtained from the green leaves, and only 31 
 from the pale leaves. 
 
 It has been mentioned in the Third Lecture, that the 
 sap probably, in common cases, descends from the leaves 
 into the bark; the bark is usually so loose in its texture, 
 that the atmosphere may possibly act upon it in the cor- 
 tical layers ; but the changes taking place in the leaves, 
 appear sufficient to ex[dain the diflerence between the 
 products obtained from the bark and from the alburnum ; 
 the first of which contains more carbonaceous matter 
 than the last. 
 
 When the similarity of the elements of diflferent ve- 
 getable products is considered, according to the views 
 given in the Third Lecture, it is easy to conceive how 
 the different organized parts may be formed from the 
 same sap, according to the manner in which it is acted 
 on by heat, light and air. By the abstraction of oxy- 
 gene, the different inflammable products, fixed and vola- 
 tile oils, resins, camphor, woody fibre, &c. may be pro- 
 duced from saccharine or mucilaginous fluids ; and by 
 the abstraction of carbon and iiydrogene, starch, sugar, 
 the diflerent vegetable acids and substances soluble in 
 water, may be formed from highly corabu«tible and in- 
 
i6^ 
 
 solu?)le substances. Even the limpid volatile oils which 
 convey the fragrance of the flower, consist of different 
 proportions of the same essential elements, as the dense 
 woody fibre ; and both are formed by different changes 
 in the same organs, from the same materials, and at the 
 same time. 
 
 M. Vauquelin has lately attempted to estimate the 
 chemical changes taking place in vegetation, by analy- 
 sing some of the organized parts of the horse-chesnut 
 in their different stages of growth. He found in ti»e 
 buds collected, March 7, 18d2, tanning principle, and 
 albuminous matter capable of being obtained separately, 
 but when obtained, comliining with each other. In the 
 scales surrounding the buds, he found the tanning prin- 
 ciple, a little saccharine matter, resin and a fixed oil. In 
 the leaves fully developed, he discovered the same prin- 
 ciples as in the buds ; and in addition, a peculiar green 
 resinous matter. The petals of the flower yielded a 
 yellowish resin, saccharine matter, albuminous matter, 
 and a little wax : the stamina afforded sugar, resin, and 
 tannin. 
 
 The young chesnuts examined immediately after their 
 formation, afforded a larger quantity of a matter which 
 appeared to be a combination of albuminous matter and 
 tannin. All the parts of the plant afforded saline com- 
 binations of the acetic and phosphoric acids. 
 
 M. Vauquelin could not obtain a sufficient quantity 
 of the sap of the horse-chesnut for examination ; a cir- 
 cumstance much to be regretted ; and he has not stated 
 the relative quantities of the different substances in the 
 buds, leaves, flowers, and seeds. It is probable, how- 
 ever, from his unfinished details, that the quantity of 
 resinous matter is increased in the leaf, and that the 
 white fibrous pulp of the chesnut is formed by the mu- 
 tual action of albuminous and astringent matter, which 
 probably are supplied by different cells or vessels. I 
 have already mentioned* that the cambium, from which 
 the new parts in the trunk and branches appear to be 
 formed, probably owes its powers of consolidation to 
 the mixture of two different kinds of sap ; one of which 
 
 *P. 104. 
 
J (i4 
 
 flo^vs upwards from the roots; and other ol' which pro- 
 bably descends from the leaves. 1 attenipledj in May 
 1804, at the time the cambium was forming in tlie oak, 
 to ascertain the nature of the action of the sap of the 
 alburnum upon the juices of the bark. By perforatine; 
 the alburnum in a youni^oak, and applying an exhaust- 
 ing syringe to the aperture, 1 easily drew out a small 
 quantity of sap. 1 could not, however, in the same way 
 obtain sap from tlie bark. 1 was obliged to recur to the 
 soluti«)n of its principles in water, by infusing a small 
 quantity of fresli bark in warm water; the liquid obtain- 
 ed in this way was highly coloured and astringent ; and 
 produced an immediate precipitate in the alburnous sap, 
 the taste of wliich was sweetish, and slightly astringent, 
 and which was colourless. 
 
 Tlie in(;reasc of trees and plants must depend upon 
 the quantity of sap which passes into their organs ; upon 
 the quality of this sap; and on this modification by the 
 principles of the atmosphere. Water, as it is the vehi- 
 cle of the nourishment of the plant, is the substance 
 principally given off by the leaves. Dr. Hales found, 
 that a sunflower, in one day of twelve liours, transpired 
 hy its leaves one pound fourteen ounces of water, all of 
 Avhich must have been imbi])ed by its roots. 
 
 The powers which cause the ascent of tlie sap have 
 heen slightly touched upon in the Second and Third 
 Lectures. The roots imbibe fluids from the soil by ca- 
 pillary attraction ; but this power aU)ne is insufficient to 
 account for the rapid elevation of the sap into the leaves. 
 This is fully proved by the following fact detailed by 
 Dr. Hales, Vol. 1. of the Vegetable Statics, page 114. 
 A vine branch of four or five years old was cut through, 
 and a glass tube carefully attached to it; this tube was 
 bent as a siphon, and filled with quicksilver; so that the 
 force of the ascending sap could be measured by its ef- 
 fect in elevating the quicksilver. In a few days it was 
 found, that the sap had been propelled forwards with 
 so much force, as to raise the quicksilver to 38 inches, 
 which Is a force considerably superior to that of the usual 
 pressure of the atmosphere. Capillary attraction can 
 only be exerted by the surfaces of small vessels, and 
 can never raise a iluid into tubes above the vessels tliem- 
 selvc.?». 
 
.165 
 
 1 Fefeired in the liegiuiiing of the Third Lecture to 
 Mr. Knight's opinion, that the contractions and expan- 
 sions of the silver grain in the alburnum, are the most 
 efficient cause of the ascent of the fluids contained in 
 its pores and vessels. The views of this excellent ])hy- 
 siologist are rendered extremely probable by the facts 
 be has brought forward in support of them. Mr. Knight 
 found that a very small increase of temperature was suf- 
 ficient to cause the fibres of the silver grain to separate 
 from each other, and that a very slight diminution of 
 heat produced their contraction. The sap rises most 
 vigorously in spring and autumn, at the time the tempe- 
 rature is variable; and if it be supposed, that in expand- 
 ing and contracting, the elastic fibres of the silver grain 
 exercise a pressure upon the cells and tubes containing 
 the fluid absorbed by tlie capillary attraction of tlie roots, 
 this fluid must constantly move upwards towards the 
 points where a supply is needed. 
 
 The experiments of Montgolfier, the celebrated in- 
 ventor of the balloon, have shewn that water may be 
 raised almost to an indefinite height by a very small 
 force, provided its pressure be taken off by continued 
 divisions in the column of fluid. This principle, there 
 is great reason to suppose, must operate in assisting the 
 ascent of the sap in the cells and vessels of plants which 
 have no rectilineal communication, and which every 
 where oppose obstacles to the perpendicular pressure of 
 the sap. 
 
 The changes taking place in the leaves and buds, and 
 the degree of their power of transpiration, must be in- 
 timately connected likewise with the motion of the sap 
 upwards. This is shewn by several experiments of Dr. 
 Hales. 
 
 A branch from an apple tree was separated and in- 
 troduced into water, and connected with a mercurial 
 gage. When the leaves were upon it, it raised the mer- 
 cury by the force of the ascending juices to four inches ; 
 but a similar branch, from which the leaves were remo- 
 ved, scarcely raised it a quarter of an inch. 
 
 Tliose trees, likewise, whose leaves arc soft and of a 
 spongy texture, and porous at their upper surfaces, dis- 
 played by far the greatest powers with regard to the ele- 
 vation of the sap. 
 
166 
 
 The same accurate philosopher whom 1 have just 
 quoted, found that the pear, quince, cherry, walnut, 
 peach, gooseberry, water- elder_, and sycamore, which 
 have all soft and unvarnished leaves, raised the mercu- 
 ry under favourable circumstances from three to six 
 inches. Whereas the elm, oak, chesnut, hazel, sallow, 
 and ash, which have firmer and more glossy leaves, 
 raised the mercury only from one to two inches. And 
 the evergreens and trees bearing varnished leaves, 
 scarcely at all affected it ; particularly the laurel and the 
 lauristinus. 
 
 It will be proper to mention the facts which shew, that 
 in many cases fluids descend through the bark ; they are 
 not of the same unequivocal nature as those which de- 
 monstrate the ascent of the sap through the alburnum ; 
 yet many of them are satisfactory. 
 
 M. Baisse placed branches of different trees in an in- 
 fusion of madder, and kept them there for a long time. 
 He found in all cases, that the wood became red before 
 tlie bark ; and that the bark began to receive no tinge 
 till the whole of the wood was coloured, and till the 
 leaves were affected ; and that the colouring matter first 
 appeared above, in the bark immediately in contact with 
 the leaves. 
 
 Similar experiments were made by M. Bonnet, and 
 with analogous results, though not so perfectly distinct 
 as those of M. Baisse. 
 
 Du Hamel found, that in different species of the pine 
 and other trees, when strips of bark were removed, the 
 upper part of the wound only emitted fluid, whilst the 
 lower part remained dry. 
 
 This may likewise be observed in the summer in fi'uit- 
 trees, when the bark is wounded, the alburnum remain- 
 ing untouched. 
 
 I have mentioned in the Third Lecture, that when 
 new bark is formed to supply the place of a ring that 
 has been stripped off, it first makes its appearance upon 
 the upper edge of the wound, and spreads slowly down- 
 wards ; and no new matter appears from below rising up- 
 wards, if the experiment has been carefully performed. 
 I say carefully performed ; because, if any of the inte- 
 rior cortical layer be suffered to remain communicating 
 -with the upper edge^ new bark chvei'ed \yjth e"pidermis 
 
167 
 
 "Will form below this, and appear as if protruded upoii 
 the naked alburnum, and formed within the wound; and 
 such a circumstance would give rise to erroneous con- 
 clusions. 
 
 In the summer of 1804, 1 examined some elms at Ken- 
 sington. The bark of many of them had been very much 
 injured, and, in some cases, more than a square foot 
 had been stripped oif. In most of the wounds the for- 
 mation of the new cortical layers was from above, and 
 gradually extending downwards round the aperture; 
 but in two instances there had been very distinctly a for- 
 mation of bark towards the lower edge. 1 was, at first, 
 very much surprised at this appearance, so contradicto- 
 ry to the general opinion ; but, on passing the point of a 
 pen- knife along the surface of the alburnum, from below 
 upwards, I found that a part of the cortical layer, which 
 was of the colour of the alburnum, had remained com-, 
 municating with the upper edge of the wound, and that 
 the new bark had formed from this layer. I have had 
 no opportunity of looking at the trees lately ; but I doubt 
 not that the phsenomenon may still be observed ; for some 
 years must elapse before the new formations will be 
 complete. 
 
 In accounting for the experiment of M. Palisot de 
 Beauvois, mentioned in the Third Lecture, it may be 
 supposed that the cortical fluid flowed down the albur- 
 num upon the insulated bark, and thus occasioned its 
 increase ; or it may be conceived that the bark itself 
 contained sufficient cortical fluid at the time of its sepa- 
 ration to form new parts by its action upon the alhur- 
 nous fluid. 
 
 The motion of the sap through the bark seems prin- 
 cipally to depend upon gravitation. When the watery 
 particles have been considerably dissipated by the tran- 
 spiring functions of the leaves, and the mucilaginous, 
 inflammable, and astringent constituents, increased by 
 the agency of heat, light, and air, the continued impulse 
 upwards from the alburnum, forces the remaining in- 
 spissated fluid into the cortical vessels, which receive 
 no other supply. In these, from its weight, its natural 
 tendency must be to descend ; and the rapidity of the 
 descent must depend u|>on the general consumption of 
 
4.68 
 
 the fluids of the bark in the living processes of vegeta- 
 tion ; for there is every reason to believe, that no fluid 
 passes into the soil tlirough the roots ; and it is impos- 
 sible to conceive a free lateral communication between 
 the absorbent vessels of the alburnum in the roots, and 
 the transporting or carrying vessels of the bark ; for if 
 such a communication existed, there is no reason why 
 the sap should not rise through the bark as well as through 
 the alburnum ; for the same physical powers would then 
 operate upon both. 
 
 Some authors have supposed that the sap rises in the 
 alburnum, and descends through the bark in consequence 
 of a power similar to that which produces the circula- 
 tion of the blood in animals ; a force analogous to the 
 muscular force in the sides of the vessels. 
 
 Dr. Thomson in his System of Chemistry, has stated 
 a fact which he considers as demonstrating the irratibi- 
 lity of living vegetable systems. When a stork of spurge 
 (Euphorbia peplis) is separated by two incisions from 
 its leaves and roots, the milky fluid flows through both 
 sections. Now, says the ingenious author, it is impos- 
 sible that this could happen without the living action of 
 the vessels, for they cannot have been more than full ; 
 and their diameter is so small, that if it were to conti- 
 nue unaltered, the capillary attraction would be more 
 than sufficient to contain their contents, and, consequent- 
 ly, not a drop would flow out. Since, therefore, the li- 
 quid escapes, it must be driven out by a force different 
 from a common physical force. 
 
 To this reasoning it may be answered, that the sides 
 of all the vessels are soft, and capable of collapsing by 
 gravitation, as veins do in animal systems long after 
 they have lost all their vitality : which is an effect to- 
 tally different from vital or irritable action ; and the 
 phsenomenon may be compared to that of puncturing a 
 vessel of elastic gum filled with fluid, both above an,d 
 below ; the fluid will make its way tlirough the aper- 
 tures, though in much larger quantity from the lowest, 
 which I have found is likewise the case with the 
 spurge. 
 
 l)r. Jjarton has stated, that plants grow more vigor- 
 misly in water in which a little camphor has been infii- 
 
169 
 
 sed. This has been brought foivvard as a fact in favour 
 of tlie iFritability of the vegetable tubular system. It 
 is said, that camphor can only be conceived to act as a 
 stimulus, by increasing the living powers of the vessels,, 
 and causing them to contract with more energy. But 
 this kind of speculation is very unsatisfactory. Cam- 
 phor, we know, has a disagreeable pungent taste, and 
 powerful smell ; but physicians are far from being 
 agreed whether it is a stimulant or sedative, even in 
 its operation upon the human body. We should have 
 no right whatever, even supposing the irritability of ve- 
 getables proved, to conclude, that because camphor as- 
 sisted the growth of plants, it acted on their living pow- 
 ers ; and it is not right to infer the existence of a pro- 
 perty proved in no other way, from the operation of un- 
 certain qualities. 
 
 That camphor may assist the growth of plants it is 
 easy to conceive ; and why should Ave not consider its 
 efficacy as similar to the efficacy of saccharine and mu- 
 cilaginous matter, and particularly of oils, to which it is 
 nearly allied in composition ; and which afford food to 
 the plant, and not stimulus ; which are materials of as- 
 similation, and not of excitement ? 
 
 The arguments in favour of a contraction similar to 
 muscular action have not then much weight; and besides, 
 there are direct facts which render the opinion highly 
 improbable. 
 
 When a single branch of a vine or other tree is intro- 
 duced in winter into a hot-house, the trunk and the other 
 branches remaining exposed to the cold atmospliere, the 
 sap will soon begin to move towards the buds in the 
 heated branch ; these buds will gradually unfold them- 
 selves, and begin to transpire ; and at length open into 
 leaves. Now if any peculiar contractions of the sap ves- 
 sels or cells were necessary for the ascent of the sap in 
 the vessels, it is not possible that the application of heat 
 to a single branch should occasion irritable action to take 
 place in a trunk many feet removed from it, or in roots 
 fixed in the cold soil : but allowing that the energy of 
 lieat raises the fluid merely by diminishing its gravity, 
 increasing the facility of capillary action, and by produ- 
 cing an expansion of the fibres of the silver grain, the 
 
 Y 
 
171) 
 
 phaenomeuou is iu perfect unison witb tlie views advan- 
 ced in the preceding part of tliis Lecture. 
 
 The ilexj or evergreen oak, preserves its leaves through 
 the winter, even when grafted upon the common oak ; and 
 in consequence of the operation of the leaves, there is a 
 certain motion of the sap towards the ilex, which, as 
 iu the last case, seems to be inconsistent with the theo- 
 ry of irritable action. 
 
 It is impossible to peruse any considerable part of the 
 Yegetable Statics of Hales, without receiving a deep 
 impression of the dependence of the motion of the sap 
 upon common physical agencies. In the same tree this 
 sagacious person observed, that in a cold cloudy morn- 
 ing when no sap ascended, a sudden change was pro- 
 duced by a gleam of sunshine, of half an hour ; and a 
 vigorous motion of the fluid. The alteration of the wind 
 from south to the north immediately checked the effect. 
 On the coming on of a cold afternoon after a hot day, 
 the sap that had been rising began to fall. A warm 
 shower and a sleet storm produced opposite effects. 
 
 Many of his observations likewise shew, that the dif- 
 ferent powers which act on the adult tree, produce dif- 
 ferent effects at different seasons. 
 
 Thus, in the early spring, before the buds expand, 
 the variations of the temperature, and changes of the 
 state of the atmosphere with regard to moisture and dry- 
 ness, exert their great effects upon the expansions and 
 contractions of the vessels ; and then the tree is in what 
 is called by gardeners its bleeding season. 
 
 When the leaves are fully expanded, the great deter- 
 mination of the sap is to these new organs. And hence 
 a tree which emits sap copiously from a wound whilst 
 the buds are opening, m ill no longer emit it in summer 
 when the leaves are perfect ; but in the variable wea- 
 ther, towards the end of autumn, when the leaves are 
 falling, it will again possess the power of bleeding in 
 a very slight degree in the warmest days ; but at no 
 other times. 
 
 Iu all these circumstances there is nothing analogous 
 to the irritable action of animal systems. 
 
 In animal systems the heart and arteries are in con- 
 stant pulsation. Their functions are unceasingly per- 
 
171 
 
 formed hi all climates, aud in all seasons ; in winter, as 
 well as in spring; upon the arctic snows, and under the 
 tropical suns. They neither cease in the periodical noc- 
 turnal sleep, common to most animals ; nor in the long 
 sleep of winter, peculiar to a few species. The power 
 is connected with animation, is limited to beings pos- 
 sessing the means of voluntary locomation ; it co-exists 
 with the first appearance of vitality; it disappears only 
 with the last spark of life. 
 
 Vegetables maybe truly said to be living systems, in 
 this sense, that they possess the means of converting the 
 elements of common matter into organized structures, 
 both by assimilation and reproduction ; but we must not 
 suffer ourselves to be deluded by the very extensive ap- 
 plication of the word life, to conceive in the life of plants, 
 any power similar to that producing the life of animals. 
 In calling forth the vegetable functions, common physi- 
 cal agents alone seem to operate ; but in the animal sys- 
 tem these agents are made subservient to a superior 
 principle. To give the argument in plainer language, 
 there are few philosophers who would be inclined to as- 
 sert the existence of any thing above common matter, 
 any thing immaterial in the vegetable economy. Such 
 a doctrine is worthy only of a poetic form. The imagi- 
 nation may easily give Dryads to our trees, and Sylphs 
 to our flowers ; but neither Dryads nor Sylphs can be 
 admitted in vegetable physiology; and for reasons near- 
 ly as strong, irritability and animation ought to be ex- 
 cluded. 
 
 As the operation of the different physical agents upon 
 the sap vessels of plants ceases, and the fluid becomes 
 quiescent, the materials dissolved in it by heat, are de- 
 posited upon the sides of the tubes now considerably 
 diminished in their diameter ; and in consequence of this 
 deposition, a nutritive matter is provided for the first 
 wants of the plant in early spring, to assist the opening 
 of their buds, and their expansion, when the motion from 
 the want of leaves is as yet feeble. 
 
 This beautiful principle in the vegetable economy was 
 first pointed out by Dr. Darwin ; and Mr. Knigiit has 
 given a number of experimental elucidations of it. 
 
All'. Kfii£;lit made, numerous incisious into tlie albui 
 iium ol* the sycamoie and thebiicb, atditTerent lieiglits; 
 and in cxaminini^ tlie sap that flowed from them, he 
 found it more sweet and mucihtginous in proportion as 
 the aperture from which it flowed was elevated ; which 
 lie could ascribe to no other cause than to its having 
 dissolved sugar and mucilage, which had been stored up 
 through the winter. 
 
 He examined the alburnum in difterent poles of oak 
 in the same forest ; of which some had been felled in 
 winter, and others in summer ; and he always found 
 most soluble matter in the wood felled in winter, and 
 its specific gravity was likewise greater. 
 
 In all perennial trees this circumstance takes place ; 
 and lii^eAvise in grasses and shrubs. The joints of the 
 perennial grasses contain more saccharine and mucila- 
 ginous matter in winter than at any other season ; and 
 this is the reason why the liorin or Agrostis alba, which 
 abounds in these joints, aftbrds so useful a winter 
 food. 
 
 The roots of shrubs contain the largest quantity of 
 nourishing matter in the depth of winter ; and the bulb 
 in all plants possessing it, is the recepticle in which nou- 
 rishment is hoarded up during winter. 
 
 In annual plants the sap seems to be fully exhausted 
 of all its nutritive matter by the production of flowers 
 and seeds, and no system exists by which it can be pre- 
 served. 
 
 When perennial grasses are cropped very close by 
 feeding cattle late in autumn, it has been often observed 
 by farmers, that tliey never rise vigorously in the spring; 
 and this is owing to the removal of that part of the stalk 
 which would have afibrded them concrete sap, their first 
 nourishment. 
 
 Ship builders prefer for their purposes that kind of 
 oak timber afforded by trees that have had their bark 
 stripped off in spring, and wliich have been cut in the 
 autumn or winter following. The reason of tlie supe- 
 riority of this timber is, that tlie concrete sap is expend- 
 ed in the spring in the sprouting of the leaf; and the 
 circulation being destroyed, it is not formed anew ; and 
 
as 
 
 ilie wood having its pores free from saccharine matter, 
 is less liable to undergo fermentation from the action of 
 moisture and air. 
 
 In perennial trees a new alburnum, and consccjuently 
 a new system of vessels, is annually produced, and the 
 nutriment for the next year deposited in them ; so that 
 the new buds like the plume of the seed, are supplied 
 with a reservoir of matter essential to their first de- 
 velopment. 
 
 The old alburnum is gradually converted into heart- 
 wood, and being constantly pressed upon by the expan- 
 sive force of the new fibres, becomes harder, denser, 
 and at length loses altogether its vascular structure ; and 
 in a certain time obeys the common laws of dead mat- 
 ter, decays, decomposes, and is converted into aeriform 
 and carbonic elements; into those principles from which 
 it was originally formed. 
 
 The decay of the heart- wood seems to constitute the 
 great limit to the age and size of trees. And in young 
 branches from old trees, it is much more liable to de- 
 compose than in similar branches from seedlings. This is 
 likewise the case with grafts. The graft is only nou- 
 rished by the sap of the tree to which it is transferred ; 
 its properties are not changed by it : the leaves, blos- 
 soms and fruits are of the same kind as if it had vege- 
 tated upon its parent stock. The only advantage to be 
 gained in this way, is the affording to a graft from an 
 old tree a more plentiful and healthy food than it could 
 have procured in its natural state ; it is rendered for a 
 time more vigorous, and produces fairer blossoms and 
 richer fruits, iiiii it partakes not merely of the obvi- 
 ous properties, but likewise of the infirmities and dis- 
 positions to old age and decay, of the tree whence it 
 sprung. 
 
 This seems to be distinctly shewn by the observations 
 and experiments of Mr. Knight. He has, in a numl>er 
 of instances, transferred the young scions and healthy 
 shoots from old esteemed fruit-bearing trees to young 
 seedlings. They flourished f(U- two or three years; but 
 they soon became diseased and sickly like their parent 
 trees. 
 
 Jt is from fliis cause that s-o many of the applr?s ftn-^ 
 
174 
 
 luei'ly celebmted lor their taste and their uses in the 
 inanulactiire of cider are gradually deteriorating, and 
 many will soon disappear. The golden pippin, the red 
 streak, and the moil, so excellent in the beginning of the 
 last century, are now in the extremest stage of their de- 
 cay ^ and however carefully they are ingrafted, tliey 
 merely tend to multiply a sickly and exhausted variety. 
 
 The trees possessing the firmest and the least porous 
 heart-wood are the longest in duration. 
 
 In general, the quantity of charcoal afforded by woods, 
 oflTers a tolerably accurate indication of their durability : 
 those most abundant in charcoal and earthy matter are 
 most permanent ; and those that contain the largest pro- 
 portion of gaseous elements are the most destructible. 
 
 Amongst our own trees, the chesnut and the oak are 
 pre-eminent as to durability ; and tlie chesnut affords 
 rather more carbonaceous matter than the oak. 
 
 In old gothic buiblings these woods have been some- 
 times mistaken one for the other; but they may be easily 
 known by this circumstance, that the pores in the albur- 
 num of the oak are much larger and more thickly set, 
 and are easily distinguished ; whilst the pores in the 
 chesnut require glasses to be seen distinctly. 
 
 In consequence of the slow decay of the heart- wood 
 of the oak and chesnut, these trees under favourable cir- 
 cumstances attain an age which cannot be much short of 
 1000 years. 
 
 The beech, the ash, and the sycamore, most likely 
 never live half as long. The duration of the apple tree 
 is not, probably, much more than 200 years ; but the 
 pear tree, according to Mr. Knight, lives through double 
 this period ; most of our best apples are supposed to 
 have been introduced into Britain by a fruiterer of Hen- 
 ry the Eighth, and they are now in a state of old age. 
 
 The oak and chesnut decay much sooner in a moist 
 situation, than in a dry and sandy soil ; and tlieir tim- 
 ber i« less firm. The sap vessels in such cases are more 
 expanded, though less nourishing matter is carried into 
 them ; and the general texture of the formations of wood 
 necessarily less firm. Such wood splits more easily, 
 and is more liable to ])e affected by variations in the state 
 M' the atnic»spliere. 
 
t Granite 
 e tineis 
 
 3 'Mictxcotms Sftis 
 
 4 Sie7tife 
 3 Serpeitthte 
 
 6 PlTflhlfTlf 
 
175 
 
 * 
 
 The same trees, in general, are much longer lived in 
 the northern than in the southern climates. The reason 
 seems to be, that all fermentation and decomposition are 
 checked by cold; and at very low temperatures both 
 animal and vegetable matters altogether resist putrefac- 
 tion : and in the northern winter, not only vegetable life, 
 but likewise vegetable decay must be at a stand. 
 
 The antiputrescent quality of cold climates is fully 
 illustrated in the instances of the rhinoceros and mam- 
 moth lately found in Siberia, entire beneath the frozen 
 soil, in which they must probably have existed from the 
 time of the deluge. I examined a part of the skin of 
 the mammoth sent to this country, on which there was 
 some coarse hair ; it had all the chemical characters of 
 recently dried skin. 
 
 Trees that grow in situations much exposed to winds, 
 have harder and firmer wood than such as are considera- 
 bly sheltered. The dense sap is determined, by the 
 agitation of the smaller branches, to the trunk and large 
 branches ; where the new alburnum formed is conse- 
 quently thick and firm. Such trees abound in the crook- 
 ed limbs fitted for forming knee-timberj which is neces- 
 sary for joining the decks and the sides of ships. The 
 gales in elevated situations gradually act, so as to give 
 the tree the form best calculated to resist their effects. 
 And the mountain oak rises robust and sturdy ; fixed 
 firmly in the soil, and able to oppose the full force of 
 the tempest. 
 
 The decay of the best varieties of fruit-bearing trees 
 which have been distributed through the country by 
 grafts, is a circumstance of great importance. There is 
 no mode of preserving them ; and no resourse, except 
 that of raising new varieties by seeds. 
 
 Where a species has been ameliorated by culture the 
 seeds it affords^ other circumstances being similar, pro- 
 duce more vigorous and perfect plants ; and in this way 
 the great improvements in the productions of our fields 
 and gardens seem to have been occasioned. 
 
 Wheat in its indigenous state, as a natural production 
 of the soil, appears to have been a very small grass : 
 and the case is still more remarkable with the apple and 
 the plum. The crab seems to have ]>uen the parent of 
 
I 
 
176 
 
 * 
 
 all our apples. And two fruits cau scarcely be coucei- 
 
 ved more diflerent in colour, size, and appearance than 
 
 the wild plum and the rich magnum bonum. 
 
 The seeds of plants exalted by cultivation always fur- 
 nish large and improved varieties ; but the flavour, and 
 even the colour of the fruit seems to be a matter of ac- 
 cident. Thus a hundred seeds of the golden pippin 
 "will all produce fine large-leaved apple trees, bearing 
 fruit of a considerable size ; but the tastes and colours 
 of the apples from each will be different, and none will 
 be the same in kind as those of the pippin itself. Som« 
 "will be sweet, some sour, some bitter, some mawkish, 
 some aromatic ; some yellow, some green, some red, and 
 some streaked. All the apples will, however, be much 
 more perfect than those from the seeds of the crab, which 
 produce trees all of the same kind, and all bearing sour 
 and diminutive fruit. 
 
 The power of the horticulturist extends only to the 
 multiplying excellent varieties by grafting. They can- 
 not be rendered permanent ; and the good fruits at pre- 
 sent in our gardens, are the produce of a few seedlings, 
 selected probably from hundreds of thousands ; the re- 
 sults of great labour and industry, and multiplied expe- 
 riments. 
 
 The larger and thicker the leaves of a seedling, and 
 the more expanded its blossoms, the more it is likely to 
 produce a good variety of fruit. Short-leaved trees 
 should never be selected ; for these approach nearer to 
 the original standard ; whereas the other qualities indi- 
 cate the influence of cultivation. 
 
 In the general selection of seeds, it would appear that 
 those arising from the most highly cultivated varieties 
 of plants, are such as give the most vigorous produce ; 
 but it is necessary from time to time to change, and as 
 it were, to cross the breed. 
 
 By applying the pollen, or dust of the stamina, from 
 one variety to the pistil of another of the same species, 
 a new variety may be easily produced ; and Mr. Knight's 
 experiments seem to warrant the idea, that great advan- 
 tages may be derived from this method of propagation. 
 
 Mr. Knight's large peas produced by crossing two 
 
177 
 
 varieties, are celebrated amongst horticulturists, and. 
 will, I hope, soon be cultivated by farmers. 
 
 1 have seen several of his crossed apples, which pro- 
 mise to rival the best of those which are gradually dy- 
 ing away in the cider countries. 
 
 And his experiments on the crossing of wheat, which 
 is very easily effected, merely by sowing the different 
 kinds together, lead to a result which is of considerable 
 importance. He says, in the Philosophical Transac- 
 tions for 1799, " in the years 1795 and 1796, when al- 
 most the whole crop of corn in the island was blighted, 
 the varieties obtained by crossing alone escaped, though 
 sown in several soils, and in very different situations. '^ 
 
 The processes of gardening for increasing the num- 
 ber of fruit- bearing branches, and for improving the 
 fruit upon particular branches, will all admit of eluci- 
 dation from the principles that have been advanced in 
 this Lecture. 
 
 By making trees espaliers, the force of gravity is par- 
 ticularly directed towards the lateral parts of tlie branch- 
 es, and more sap determined towards the fruit buds ; and 
 hence they are more likely to bear when in a horizontal 
 than when in a vertical position. 
 
 The twisting of a wire, or tying a thread round a 
 branch has been often recommended as a means of ma- 
 king it produce fruit. In this case the descent of the 
 sap in the bark must be impeded above the ligature ; and 
 more nutritive matter consequently retained and appli- 
 ed to the expanding parts. 
 
 In engrafting, the vessels of the bark of the stock and 
 the graft cannot so perfectly come in contact as the al- 
 burnous vessels, which are much more numerous, and 
 equally distributed ; hence the circulation downwards is 
 probably impeded, and the tendency of the graft to evolve 
 its fruit-bearing buds increased. 
 
 By lopping trees, more nourishment is supplied to the 
 remaining parts ; for the sap flows laterally as well as 
 perpendicularly. The same reasons will apply to ex- 
 plain the increase of the size of fruits by diminishing 
 the number upon a tree. 
 
 As plants are capable of amelioration by peculiar me- 
 thods of cultivation, and of having the natural term of 
 
178 . 
 
 iheir duration extended ; so, in conformity to the gene- 
 ral law of change, they are rendered unhealthy by be- 
 ing exposed to peculiar unfavourable circumstances, and 
 liable to premature old age and decay. 
 
 The plants of warm climates transported into cold 
 ones, or of cold ones transported iulo warm ones, if not 
 absolutely destroyed by the change of situation, are uni- 
 formly rendered unhealthy. 
 
 Few of the tropical plants, as is well known, can be 
 raised in this country, except in hot houses. The vine 
 during the whole of our summer may be said to be in a 
 feeble state with regard to health ; and its fruit, except 
 in very extraordinary cases, always contains a supera- 
 bundance of acid. The gigantic pine of the north, when 
 transported into the equatorial climates, becomes a de- 
 generated dwarf ; and a great number of instances of the 
 same kind might be brought forward. 
 
 Much has been w ritten, and many very ingenious re- 
 marks have been made by different philosophers upon 
 what have been called the habits of plants. Thus, in 
 transplanting a tree, it dies or becomes unhealthj', un- 
 less its position with respect to the sun is the same as 
 before. The seeds brought from warm climates germi- 
 nate here much more early in the season than the same 
 species brought from cold climates. The apple tree 
 from Siberia, where the short summer of three mouths 
 immediately succeeds the long winter, in England, usu- 
 ally puts forth its blossoms in the first year of its trans- 
 plantation, on the appearance of mild weather; and is 
 often destroyed by the late frosts of the spring. 
 
 It is not ditlicult to explain this principle so intimate- 
 ly connected with the healthy or diseased state of plants. 
 The organization of the germ, whether in seeds or buds, 
 must be different according as more or less heat, or al- 
 ternations of heat and cold, have afl'ected it during its 
 formation ; and the nature of its expansion must depend 
 wholly on this organization. In a changeable climate 
 the formations will have been interrupted, and in dif- 
 ferent successive layers. In an equable temperature they 
 will liave been uniform ; and the operation of new and 
 sudden causes will of course be severely felt. 
 
 Tlie disposilion of trees may, however, be chauged 
 
i79 
 
 gradually in many instances; and the operation of anew 
 climate in this way be made supportable. The myrtle, 
 a native of the south of Europe, inevitably dies if ex- 
 posed in the early days of its grov^^th to the frosts of our 
 winter; but if kept in a green-house during the cold 
 seasons for successive years, and gradually exposed to 
 low temperatures, it will, in an advanced stage of growth, 
 resist even a very severe cold. And in the south and 
 west of England tiie myrtle flourishes, produces blos- 
 soms and seeds, in consequence of this process, as an 
 unprotected standard tree ; and the layers from such 
 trees are much more hardy than the layers from myrtles 
 reared within doors. 
 
 The arbutus, probably originally from similar culti- 
 vation has become the principal ornament of the lakes 
 of the south of Ireland. It thrives even in bleak moun- 
 tain situations; and there can ])e little doubt but that the 
 offspring of this tree inured to a temperate climate might 
 be easily spread in Britain. 
 
 The same princijiles that apply to the effects of heat 
 and cold will likewise apply to the influence of moisture 
 and dryness. The layers of a tree habituated to a moist 
 soil will die in a dry one : even though such a soil is 
 more favourable to the general growtli of the species. 
 And, as was stated, page 132, trees that have been raised 
 in the centre of woods, are sooner or later destroyed, if 
 exposed in their adult state to blasts, in consequence of 
 the felling of the surrounding timber. 
 
 Trees, in all cases, in which they are exposed in high 
 and open situations to the sun, the winds, and the rain, 
 as I just now noticed, become low and robust, exhibit- 
 ing curved limbs, but never straight and graceful trunks. 
 Shrubs and trees, on the contrary, which are too much 
 sheltered, too much secluded from the sun and wind ex- 
 tend exceedingly in height; but present at the same time 
 slender and feeble branches, their leaves are pale and 
 sickly, and in extreme cases they do not bear fruit.' The 
 exclusion of light alone is sufficient to produce this spe- 
 cies of disease, as would appear from the experiments 
 of Bonnet. This ingenious physiologist sowed three 
 seeds of the pea in the same kind of soil : one he suf- 
 fered to remain exposed to the free air ; the other he eii- 
 
« losetl in ;i lube of glass ; ami tlie (bird in a tube of 
 Avood. Tbe pea in tlie tube of glass sprouted, and grew 
 in a manner scarcely at all difterent from that under 
 usual circumstances; but the plant in the tube of wood, 
 deprived of light, became white, and slender, and grew 
 to a much greater height. 
 
 The plants growing in a soil incapable of supplying 
 them with sufficient manure or dead organized matter, 
 arc generally very low ; having brown or dark green 
 leaves, and their woody fibre al)ounds in earth. Those 
 vegetating in peaty soils, or in lands too copiously sup- 
 plied with animal or vegetable matter, rapidly expand, 
 produce large bright green leaves, abound in sap, and 
 generally blossom prematurely. 
 
 Where a land is too rich for corn it is not an uncom- 
 mon practice to cut down tlie first stalks, as by these 
 means its exuberance is corrected, and it is less likely 
 to fall before the grain is ripe ; excess of poverty or of 
 richness is almost equally fatal to the hopes of the farm- 
 er : and the true constitution of the soil for the best crop 
 is that in whicli the earthy materials, the moisture and 
 manure, arc properly associated ; and in which the de- 
 composable vegetable or animal matter does not exceed 
 one- fourth of the weight of tbe earthy constituents. 
 
 The canker, or erosion of the bark and wood, is a dis- 
 ease produced often in trees by a poverty of soil ; and 
 it is invariably connected with old age. The cause 
 seems to Jbe an excess of alkaline and earthy matter in 
 the descending sap. 1 have often found carbonate of 
 lime on the edges of the canker in apple trees ; and ul- 
 min, which contains fixed alkali, is abundant in the can- 
 ker of the elm. The old age of a tree, in this respect, 
 is faintly analogous to the old age of animals, in whicli 
 the secretions of solid bony matter arc always in excess, 
 and the tendency to ossification great. 
 
 The common modes of attempting to cure the canker, 
 are by cutting the edges of the bark, binding the new 
 bark upon it, or laying on a plaster of earth ; but these 
 methods, though they have been much extolled, proba- 
 bly do very little in producing a regeneration of the part. 
 Perhaps the application of a weak acid to the canker 
 might be of use ; or, where the tree is of great value, it 
 
181 . 
 
 may be watered occasionally with a very diluted acid. 
 Tlie alkaline and earthy nature of the morbid secretion 
 warrants the trial ; but circumstances that cannot be 
 foreseen may occur to interfere with the success of the 
 experiment. 
 
 Besides the diseases having their source in the consti- 
 tution of the plant, or in the unfavourable operation of 
 external elements, there are many others perhaps more 
 injurious, depending upon the operations and powers of 
 other living beings ; and such are the most difficult to'^ 
 cure, and the most destructive to the labours of the hus- 
 bandman. 
 
 Parasitical plants of different species, which attach 
 themselves to trees and shrubs, feed on their juices, de- 
 stroy their health, aiul finally their life, abound in all 
 climates ; and are perhaps, the most formidable of the 
 enemies of the superior and cultivated vegetable species. 
 The mildew, which has often occasioned great ha- 
 vock in our wheat crops, and which was particularly 
 destructive in 1804, is a species of fungus, so small as 
 to require glasses to render its form distinct, and rapidly 
 propagated by its seeds. 
 
 This has been shewn by various botanists ; and the 
 subject has received a full illustration from the enlight- 
 ened and elaborate researches of the President of the 
 iioyal Society. 
 
 The fungus rapidly spreads from stalk to stalk, fixes 
 itself in the cells connected with the common tubes, and 
 carries away and consumes that nourishment which 
 should have been appropriated to the grain. 
 
 No remedy has as yet been discovered for this disease ; 
 but as the fungus increases by the diff'usion of its seeds, 
 great care should be* taken that no mildewed straw is 
 carried in the manure used for corn ; and in the early crop, 
 if mildew is observed upon any of tlie stalks of corn, 
 they should be carefully removed and treated as weeds. 
 The popular notion amongst farmers, that a barberry- 
 tree in the neighbourhood of a field of wheat often pro- 
 duces the mildev/, deserves examination. This tree is 
 frequently covered with a fungus, which if it should be 
 shewn to be capable of degenerating into the wheat fun-' 
 gus, would offer an easy explanation of tlie effect. 
 
482 
 
 There is every reason to believe, from the researches 
 of Sir Joseph Banks, that the smut in wheat is produ- 
 ced by a very small. fungus which fixes on the grain : 
 the products that it affords by analysis are similar to 
 those afforded by the puff-ball; and it is difficult to con- 
 ceive, that without the agency of some organized struc- 
 ture, so complete a change should be effected in the con- 
 stitution of the grain. 
 
 The misletoe and the ivy, the moss and the lichen, in 
 fixing upon trees, uniformly injure their vcigetative pro- 
 cesses, though in very different degrees. They are sup- 
 ported from the lateral sap vessels, and deprive the bran- 
 ches above of a part of their nourishment. 
 
 The insect tribes are scarcely less injurious than the 
 parasitical plants. 
 
 To enumerate all the animal destroyers and tyrants 
 of the vegetable kingdom would be to give a catalogue 
 of the greater number of the classes in zoology. Every 
 species of plant, almost, is the peculiar resting place, or 
 dominion of some insect tribe ; and from the locust, the 
 caterpillar, and snail, to the minute aphis, a wonderful 
 variety of the inferior insects are nourished, and live by 
 their ravages upon the vegetable world. 
 
 I have already referred to the insect which feeds on 
 the seed-leaf of the turnip. 
 
 The Hessian fly, still more destructive to wheat, has 
 in some seasons threatened the United States with a fa- 
 mine. And the French government is at this time* is- 
 suing decrees with a view to occasion the destruction of 
 the larvas of the grasshopper. 
 
 In general, wet weather is most favourable to the 
 propagation of mildew, funguses, rust, and the small pa- 
 jasitical vegetables ; dry weather to the increase of the 
 insect tribes. Nature, amidst all her changes, is con- 
 tinually directing her resources towards the production 
 and multiplication of life ; and in the wise and grand 
 economy of the whole system, even the agents that ap- 
 pear injurious to the hopes, and destructive to the com- 
 forts of man, are in fact ultimately connected with a more 
 exalted state of his powers and his condition. His in- 
 
 * January, 18 1 3*. 
 
183 
 
 tlustry is awakeiie<i, Iiis activity kept alive, even by the 
 defects of climates and season. By the accidents which 
 interfere with his eflbrts, he is made to exert his talents, 
 to look farther into futurity, and to consider the vege- 
 table kingdom not as a* secure and inalterable inheri- 
 tance, spontaneously providing for his wants ; but as a 
 doubtful and insecure possession, to be preserved only 
 by labour, and extended and perfected by ingenuity. 
 
LECTUKE YL 
 
 Of Manures of vegetable and animal Origin. Of the 
 Manner iyi which they become the nourishment of the 
 Plant. Of Fermentation and Putrefaction. Of the 
 different Species of Manures of Vegetable Origin ; 
 of the different Species of animal Origin, Of mix- 
 ed Manures. General Principles with resjject to the 
 Use and Application of such Manures. 
 
 X HAT certain vegetable and animal substances intro- 
 duced into the soil accelerate vegetation and increase 
 the produce of crops, is a fact known since the earliest 
 period of agriculture ; but the manner in which manures 
 act, the best modes of applying them, their relative va- 
 lue and durability, are still subjects of discussion. In 
 this Lecture I shall endeavour to lay down some settled 
 principles on these objects ; they are capable of being 
 materially elucidated by the recent discoveries in che- 
 mistry ; and I need not dwell on their great importance 
 to farmers. 
 
 The pores in the fibres of the roots of plants are so 
 small, tliat it is with difficulty they can be discovered 
 by the microscope ; it is not therefore proba])le, that solid 
 substances can pass into them from the soil. 1 tried an 
 experiment on this subject ; some impalpable powdered 
 charcoal procured by washing gunpowder, and dissipa- 
 ting the sulphur by heat, was placed in a phial contain- 
 ing pure water, in which a plant of peppermint was 
 growing : the roots of the plant were pretty generally in 
 contact with the charcoal. The experiment was made 
 in the beginning of May, 1805 ; the growth of the plant 
 was very vigorous during a fortniglit, when it was taken 
 out of the phial : the roots were cut through in different 
 parts ; but no carbonaceous matter could be discovered 
 in them, nor were the smallest filnils blackened by 
 
185 
 
 charcoal, though this must have been the case had the 
 charcoal been absorbed in a solid form. 
 
 No substance is more necessary to plants than car- 
 bonaceous matter; and if this cannot be introduced into 
 the organs of plants except in a state of solution, there 
 is every reason to suppose that other substances less es- 
 sential will be in the same case. 
 
 I found, by some experiments made in 1804, that 
 plants introduced into strong fresh solutions of sugar, 
 mucilage, tanning principle, jelly, and other substances 
 died ; but that plants lived in the same solutions after 
 they had fermented. At that time, 1 supposed that fer- 
 mentation was necessary to prepare the food of plants ; 
 but I have since found that the deleterious effect of the 
 recent vegetable solutions was owing to their being too 
 concentrated ; in consequence of which the vegetable or- 
 gans were probably clogged with solid matter, and the 
 transpiration by the leaves prevented. In the beginning 
 of June, in the next year, 1 used solutions of the same 
 substances, but so much diluted, that there was only 
 about one-two hundreth part of solid vegetable or ani- 
 mal matter in the solutions. Plants of mint grew luxu- 
 riantly in all these solutions ; but least so in that of the 
 astringent matter. I watered some spots of grass in a 
 garden with the different solutions separately, and a 
 spot witli common water : the grass watered with solu- 
 tions of jelly, sugar, and mucylage, grew most vigorous- 
 ly; and that watered with the solution of the tanning 
 principle grew better thau that watered with common 
 water. 
 
 I endeavoured to ascertain wlietlier soluble vegetable 
 substances passed in an unchanged state into the roots 
 of plants, by comparing the products of the analysis of 
 the roots of some plants of mint that had grqwn, some 
 in common water, some in a solution of sugar. One 
 hundred and twenty grains of the roots of the mint which 
 grew in the solution of sugar, afforded five grains of 
 pale green extract, which had a sweetish taste, but which 
 slightly coagulated by the action of alcohol. One hun- 
 dred and twenty grains of the roots of the mint which 
 had grown in (common water yielded three grains and a 
 half of extract, which was of a deep olive colour ; its 
 
 A a 
 
186 
 
 taste was sweetish, but more astriiigent thati tliat of the 
 other extract, and it coagulates more copiously with al- 
 coliol. 
 
 These results though hot quite decisive, favour the 
 opinion that sohible matters pass unaltered into tlie roots 
 of plants ; and the idea is confirmed by the circumstance 
 that the radical fibres of plants made to grow in infu- 
 sions of madder are tinged red, and it may be consider- 
 ed as almost proved by the fact, that substances which 
 are even poisonous to vegetables are absorbed by them. 
 I introduced the roots of a primrose into a weak solution 
 of oxide of iron in vinegar, and suflcred it to remain in 
 it till the leaves became yellow ; the roots were then 
 carefully washed in distilled water, bruised, and boiled 
 in a small quantity of the same fluid : the decoction of 
 them passed through a filtre was examined by the test 
 of infusion of nut-galls ; the decoction gained a strong 
 tint of purple, which proves that solution of iron had 
 been taken up by the vessels or pores in the roots. 
 
 Vegetable and animal substances deposited in the soil, 
 as is shewn by universal experience, are consumed du- 
 ring the process of vegetation ; and they can only nou- 
 rish the plant by aiTording solid matters capable of be- 
 ing dissolved by water, or gaseous substances capable of 
 being absorbed by the fluids in the leaves of vegetables; 
 but such parts of them as are rendered gaseous, and that 
 pass into the atmosphere, must produce a comparative- 
 ly small eflect, for gases soon become difl['used through 
 the mass of the surrounding air. The great object in 
 the application of manure should be to make it afford 
 as much soluble matter as possible to the roots of the 
 plant; and that in a slow and gradual manner, so that 
 it may be entirely consumed in .forming its sap and or- 
 ganized parts. 
 
 Mucilaginous, gelatinous, saccharine, oily, and extrac- 
 tive fluids, and solution of carbonic acid in water, are 
 substances that in their unchanged states contain almost 
 all the principles necessary for the life of plants ; but 
 there are few cases in which they can be applied as ma- 
 nures in their pure forms ; and vegetable manures, in 
 general, contain a great excess of fibrous and insoluble 
 matter, which nuist undergo chemical changes before 
 they can become the iood of plants. 
 
It will he. proper (o lake a scientific view ol" tin uaim* 
 of these changes ; of tlio causes which occasion them, 
 and which accelerate or retard them ; and of the pro- 
 ducts they atibrd. 
 
 If any fresh vegetable matter which contains sugar, 
 mucilage, starch, or otiier of the vegetable compounds 
 soluble in water be moistened and exposed to air, at a 
 temperature from 55^ to 80°, oxygene will soon be .ab- 
 sorbed, and carl)onic acid formed : heat will be produ- 
 ced, and clastic fluids principally carbonic acid, gaseous 
 oxide of carbon, and hydro-carbonate will be evolved ; 
 a dark coloured liquid, of a slightly sour or bitter taste, 
 will likewise be formed; and if the process lie suffered 
 to continue for a time sufficiently long, nothing solid will 
 remain, except earthy and saline matter, coloured black 
 by charcoal. 
 
 The dark-coloured fluid formed in the fermentation 
 always contains ascetic a'cid; and when albumen or glu- 
 ten exists in the vegetable substance, it likewise contains 
 volatile alkali. 
 
 In proportion as there is more gluten, albumen, or 
 matters soluble in water in the vegetable substances ex- 
 posed to fermentation, so in proportion, all other circum- 
 stances being equal, will the process be more rapid. 
 Pure woody fibre alone undergoes a change very slow- 
 ly; but its tex^ire is broken down, and it is easily resol- 
 ved into new elements, when mixed with substances 
 more liable to change, containing more oxygene and iiy- 
 drogene. Volatile and fixed oils, resins and wax, are 
 more susceptible of change than Avoody fibre, wlien ex- 
 posed to air and water; but much less liable than the 
 other vegetable compounds ; and even the most inflam- 
 mable substances by the absorption of oxygene, become 
 gradually soluble in water. 
 
 Animal matters in general are more liable to decom- 
 pose than vegetable sui)stances ; oxygene is absorbed, 
 and carbonic acid and ammonia formed in the process 
 of their putrefaction. They produce foited com|)oinid 
 elastic fluids, and likewise azote : they afford dark-co- 
 loured acid and oily fluids, and leave a residuum of salts 
 and earths mixed with carbonaceous matter. 
 
 The principal substances which constitute the differ- 
 
e.nt parts of iuiiaiuls, or which arc found in their blooil, 
 their secretions, or their excrements^ are gelatine, fibrine, 
 mucus, fatty, or oily matter, albumen, urea, uric acid, 
 and diiferent acid, saline, and earthy matters. 
 
 Of these gelatine is the substance which when com- 
 bined with water forms jelly. It is very liable to pu- 
 trefaction. Accordini; to M. M. Gay Lussac and The- 
 iiard^ it is composed of 
 
 47.88 of carbon. 
 27.207 - oxyj^ene. 
 
 7.914 - hydrogene. 
 16.998 
 
 These proportions cannot be considered as definite, 
 for they do not bear to each otiicr the ratios of any sim- 
 ple multiples of the number representing the elements ; 
 the case seems to be the same with other animal com- 
 pounds : and even in vegetable substances, in general, 
 as appears from the statements given in the Third Lec- 
 ture, the proportions are far from having the same sim- 
 ple relations as in tlie binary compounds capable of be- 
 ing made artificially, such as acids, alkalies, oxides, 
 and in salts. 
 
 Fibrine constitutes the basis of the muscuLar fibre of 
 animals, and a similar substance may be obtained from 
 recent fluid blood ; by stirring it with a stick the fibrine 
 >vill adhere to the stick. It is not solubl»in water; but 
 by the action of acids, as Mr. Katchett has shewn, it be- 
 comes soluble, and analogous to gelatine. It is less 
 disposed to putrefy than gelatine. According to M. M. 
 Gay Lussac and Thcnard, 100 parts of fibrine contain 
 Of Carbon - 53.360 
 Oxygene - 19.685 
 Hydrogene 7.021 
 
 Azote - 19.934 
 
 Mucus is very analogous to vegetable gmn in its cha- 
 racters ; and as Dr. Bostock has stated, it may be ob- 
 tained by evaporating saliva. No experiments have 
 been made upon its analysis ; but it is probably similar 
 to gum in composition. It is ca|)able of undergoing pu- 
 trefjiction, but less rapidly than fibrine. 
 
 •Animal fat anil oils have not been accurately analy- 
 zed j but there is great reason to suppose that their com- 
 
189 
 
 position is analogous to that of similar substances from 
 the vegetable kingdom. 
 
 Albumen has been already referred to, and its analy- 
 sis stated in the Third Lecture. 
 
 Urea may be obtained by the evaporation of human 
 urine, till it is of the consistence of a syrup; and the ac- 
 tion of alcohol on the crystalline substance which forms 
 when the evaporated matter cools. In this way a solu- 
 tion of urea in alcohol is procured, and the alcohol may 
 be separated from the urea by heat. Urea is very solu- 
 ble in water, and is precipitated from water by diluted 
 nitric acid in the form of bright pearl-coloured crystals ; 
 this property distinguishes it from all other animal sub- 
 stances. 
 
 According to Fourcroy and Vauquelin, 100 parts of 
 urea when distilled yield 
 
 92.027 parts of carbonate of ammonia. 
 4.608 carburetted hydrogene gas. 
 3.225 of charcoal. 
 Urea, particularly when mixed with albumen or gela- 
 tine, readily undergoes putrefaction. 
 
 tiric acidj as has been shewn by Dr. Egan, may be 
 obtained from human urine by pouring an acid into it ; 
 and it often falls down from urine in the form of brick- 
 coloured crystals, it consists of carbon, hydrogene, 
 oxygene, and azote : but their proportions have not yet 
 been determined. Uric acid is one of the animal sub- 
 stances least liable to undergo the process of putrefac- 
 tion. 
 
 According to the different proportions of these princi- 
 ples in animal compounds, so are the changes they un- 
 dergo different. When there is much saline or earthy 
 matter mixed or combined with them, the progress of 
 their d'^composition is less rapid than when they are 
 principally composed of fibrine, albumen, gelatine, or 
 urea. 
 
 The ammonia given off from animal compounds in 
 putrefaction may be conceived to be formed at the time 
 of their decomposition by the combination of hydrogene 
 and azote ; except this matter, the other products of pu- 
 trefaction are analogous to those afforded by the fer- 
 mentation of vegetable substances; and the soluble sub- 
 stances formed abound in the elements, which are the 
 
190 
 
 constitucut parts of vegetables, in carbon, hydrogene, 
 and oxygene. 
 
 Wliencver manures consist principally of matter solu- 
 ble in water, it is evident that their fermentation or pu- 
 trefaction should be prevented as much as possible ; and 
 the only cases in which these processes can be useful, 
 are wlien the manure consists principally of vegetable or 
 animal fibre. The circumstances necessary for the pu- 
 trefaction of animal substances are similar to those re- 
 quired for the fermentation of vegetable substances ; a 
 temperature above the freezing point, the presence of 
 water, and the presence of oxygene, at least in the first 
 stage of the process. 
 
 To prevent manures from decomposing, they should 
 be preserved dry, defended from the contact of air, and 
 kept as cool as possible. 
 
 Salt and alcohol appear to owe their powers of pre- 
 serving animal and vegetable substances to their attrac- 
 tion for water, by which they prevent its decomposing 
 action, and likewise to their excluding air. The use of 
 ice in preserving animal substances is owing to its keep- 
 ing their temperature low. The efficacy of M. Appert's 
 method of preserving animal and vegetable substances, 
 an account of which has been lately published, entirely 
 depends upon the exclusion of air. This method is by 
 filling a vessel of tin plate or glass with the meat or ve- 
 getables ; soldering or cementing the top so as to render 
 the vessel air tight ; and then keeping it half immersed 
 in a vessel of boiling water for a sufficient time to ren- 
 der the meat or vegetables proper for food. In this last 
 process it is probable that tho small quantity of oxygene 
 remaining in the vessel is absorbed ; for on opening a 
 tinned iron canister which had been filled with raw beef 
 and exposed to hot water the day before, I found that 
 the minute quantity of clastic fluid which could be pro- 
 cured from it, was a mixture of carbonic acid gas and 
 azote. 
 
 Where meat or vegetable food is to be preserved on 
 a large scale, for the use of the navy or army for in- 
 stance, I am inclined to believe, that by forcibly throw- 
 ing a quantity of carbonic acid, hydrogene, or azote, into 
 tlie vessel, by means of a compressing pump, similar to 
 that used for making artificial Seltzer water, any change 
 
191 
 
 ill the substance would be more ettectually prevented. 
 \So elastic fluid in this case would have room to form 
 by the decomposition of the meat ; and the tightness 
 and strength of the vessel would be proved by the pro- 
 cess. No putrefaction or fermentation can go on with- 
 out the generation of elastic fluid ; and pressure would 
 probably act with as much efficacy as cold in the preser- 
 vation of animal or vegetable food. 
 
 As different manures contain different proportions of 
 the elements necessary to vegetation, so they require a 
 different treatment to enable them to produce their full 
 effects in agriculture. 1 shall therefore describe in de- 
 tail the properties and nature of the manures in common 
 use, and give some general views respecting the best 
 modes of preserving and applying them. 
 
 All green succulent plants contain saccharine or mu- 
 cilaginous matter, with woody fibre, and readily ferment. 
 They cannot, therefore, if intended for manure, be used 
 too soon after their death. 
 
 When gree7i crops arc to be employed for enriching 
 a soil, they should be ploughed in, if it be possible, 
 when in flov/er^ or at the time the flower is beginning to 
 appear, for it is at this period that tliey contain the 
 largest quantity of easily soluble matter, and that their 
 leaves are most active in forming nutritive matter. 
 Green crops, pond weeds, the paring of hedges or ditches, 
 or any kind of fresh vegetable matter, requires no pre- 
 paration to fit them for manure. The decomposition 
 slowly proceeds beneath the soil ; the soluble matters are 
 gradually dissolved, and the slight fermentation that goes 
 on checked by the want of a free communication of air, 
 tends to render the woody fibre soluble without occasion- 
 ing the rapid dissipation of elastic matter. 
 
 When old pastures are broken up and made arable, 
 not only has the soil been enriched- by the death and 
 slow decay of the plants which have left soluble matters 
 in the soil; but the leaves and roots of the grasses liv- 
 ing at the time and occupying so large a part of the 
 surface, afford saccharine, mucilaginous, and extractive 
 matters, which become immediately the food of the crop, 
 and the gradual decomposition affords a supply for suc- 
 cessive years. 
 
Ili2 
 
 Rajm cake, which is used with great success as a ma- 
 nure, contains a large quantity of mucilage, some albu- 
 minous matter, and a small quantity of oil. This ma- 
 nure should be used recent, and kept as dry-as possible 
 before it is applied. It forms an excellent dressing for 
 turnip crops ; and is most oeconomically applied by be- 
 ing thrown into the soil at the same time with the seed. 
 Whoever wishes to see this practice in its highest de- 
 gree of perfection, should attend Mr. Coke's annual 
 sheep-shearing at Holkham. 
 
 Malt dust consists chiefly of the infant radicle sepa- 
 rated from the grain. I have never made any experi- 
 ment upon this manure ; but there is great reason to sup- 
 pose it must contain saccharine matter, and this will ac- 
 count for its powerful eftccts. Like rape cake it should 
 be used as dry as possible, and its fermentation prevented. 
 
 Linseed cake is too valuable as a food for cattle to be 
 much employed as a manure ; the analysis of linseed 
 was referred to in the Third Lecture. The water in 
 which ^0^ and hemj) are steeped for the purpose of ob- 
 taining the pure vegetable iibre, has considerable ferti- 
 lizing powers. It appears to contain a substance ana- 
 logous to albumen, ancl likewise much vegetable extrac- 
 tive matter. It putrefies very readily. A certain de- 
 gree of fermentation is absolutely necessary to obtain 
 the flax and hemp in a proper state ; the water to which 
 they have been exposed should therefore be used as a 
 manure as soon as the vegetable fibre is removed from it. 
 
 Sea weeds f consisting of diflerent species of fuci, al- 
 gjE, and conferva'., are much used as a manure on the 
 sea coasts of Britain and Ireland. By digesting the 
 common fucus, which is the sea weed usually most abun- 
 dant on the coast, in boiling water, I obtained from it 
 one-eighth of a gelatinous substance which had charac- 
 ters similar to mucilage. A quantity distilled gave 
 nearly four-iifths of its weight of water, but no ammo- 
 nia ; the water had an empyreumatic and slightly sour 
 taste ; the ashes contained sea salt, carbonate of soda, 
 and carbonaceous matter. The gaseous matter afforded 
 was small in quantity, principally carbonic acid and gas- 
 eous oxide of carbon, witli a little hydro-carbonate. 
 This manure is transient in its effects, and does not last 
 
193 
 
 for more than a single crop, which is easily accounted 
 for from the lar£;c quantity of water, or the elements of 
 water, it contains. It decays without producing heat 
 wlien exposed to tlic atmosphere, and seems, as it were, 
 to melt down and dissolve away. 1 have seen a large 
 heap entirely destroyed in less than two years, nothing 
 remaining l)ut a little hlack iihrous matter. 
 
 I suffered some of the firmest part of a fucus to remain 
 iu a close jar, containing atmospheric air, for a fortnight : 
 in this time it had become very much shrivelled ; the 
 sides of the jar were lined with dew. The air examined 
 was found to have lost oxygene, and contained carl)onic 
 acid gas. 
 
 Sea weed is sometimes suflered to ferment before it 
 is used ; but this process seems wholly unnecessary, for 
 there is no fibrous matter rendered soluble in the pro- 
 cess, and a part of the manure is lost. 
 
 The best farmers in the west of England use it as 
 fresh as it can be procured ; and the practical results 
 of this mode of applying it are exactly conformable to 
 the theory of its operation. The carbonic acid formed 
 by its incipient fermentation must be partly dissolved 
 by the water set free in the same process ; and thus be- 
 come capable of absorption by the roots of plants. 
 
 The effects of the sea weed, as manure, must princi- 
 pally depend upon this carbonic acid, and upon tlic so- 
 luble mucilage the weed contains ; and I found that some 
 fucus which had fermented so as to have lost about half 
 its weight, afforded less tlian one-twelfth of mucilaginous 
 matter ; from which it may be fairly concluded that some 
 of this substance is destroyed in fermentation. 
 
 Jhy straw of wheat, oats, barley, beans, and ])eas, 
 and spoiled hay, or any other similar kind of dry vege- 
 table matter, is, in all cases, useful manure. In gene- 
 ral, such substances are made to ferment before th(iy arc 
 employed, though it may be doulited whether the prac- 
 tice should be indiscriminately adoi>ted. 
 
 From 400 grains of dry barley straw 1 obtained eight 
 grains of matter soluble in water, which had a brown 
 colour, and tasted like mucilage. • From 400 grains of 
 wheateu straw I obtained five grains of a similar sub- 
 stance> 
 
 B h 
 
194 
 
 Their (an ho, no doubt Unit tlic straw of (liHevcntcroixs 
 IinmcdiaU'ly |)loiii;'ho(l into the £;rouiul allords noun.sh- 
 nicnt to i»lanLs; hut tlunr is an ohjrciion to this uioihod 
 of usiiii; straw from the difficulty of luiryinj; loui; straw, 
 and from its renchuini:; the, husbaiulry foul. 
 
 When straw is made to ferment, it liccomcs a more 
 inanai;eahle nianure; Init there is likewise, on the whole, 
 a i^reat loss of nutritive matter. More manure is per- 
 liaps sup[)lied for a siiij^le crop; !>nt the land is less im- 
 proved than it wonid he, supposini; the whole of the ve- 
 j^etable matter could be iinely divided and mixed with 
 the soil. 
 
 It is usual to carry straw that can be employed for no 
 other purpose to the dunghill, to ferment, and decom- 
 pose ; but it is worth experiment, whether it may not be 
 more economically applied when chopped small by a 
 proper mat hine, and kept dry till it is plouti;hejl in for 
 the use of a crop. li» this case, thoniijh it would decom- 
 pose much more slowly, and produce less effect at first, 
 yet its inlluence would be mu( h more lasting. 
 
 Mere wood if fibre seems to be the only vegetable mat- 
 ter that reqtiires fermentation to render it nutritive to 
 plants. Tanners' spent bark is a substance of this kind. 
 Mr. Vouui;', in his excellent Kssay on Manures, which 
 gained him the Hedfordian nu'dal of the Hath Agricul- 
 tural Society, states, ^' that si)ent bark seemed rather to 
 injure than assist vegetation;"'' which he attributes to 
 the astringent matter that it contains. Hut, in fact, it is 
 freed from all soluble substances, by the operation of 
 water in the tan- pit; and if injurious to vegetation, the 
 elVect is prohably owing to its agency u[»on water, or to 
 its mechanical etVects. It is a substance very absorbent 
 and retenti^ e of moisture, and yet not penetrable by the 
 roots of plants. 
 
 Inert peatu matter is a substance of the same kind. It 
 renmijis for years exposed to water and air without un- 
 dergoing change, and in this state yields little or no nou- 
 rishment to plants. 
 
 AVoody llbre will not ferment unless some substances 
 are mixed with it, which act the same part as the muci- 
 lage, sugar, and extractive or albuminous matters, with 
 Aviiich it is iisnallv associated in herbs and succulent vc- 
 
195 
 
 getabies. Lord Meadowbank has, judiciousiy recom 
 mended a mixture of common farm-yard dung for the 
 purpose of bringing peats into fermentation; any putres- 
 cible or fermentable substance will answer the end ; and 
 the more a substance heats, and the more readily it fer- 
 ments, the better will it be fitted for the purpose. 
 
 Lord Meadowbank states, that one part of dung is 
 sufficient to bring three or four parts of peat into a state 
 in which it is fitted to be applied to land ; but of course 
 the quantity must vary according to the nature of the 
 dung and of the peat. In cases in which some living 
 vegetables are mixed with the peat, the fermentation 
 will be more readily eflfected. 
 
 Tanners' spent bark, shavings of wood and saw-dust, 
 will probably require as much dung to bring them into 
 fermentation as the worst kind of peat. 
 
 Woody fibre may be likewise prepared so as to be- 
 come a manure, by the action of lime. This subject I 
 shall discuss in the next Lecture, as it follows natural- 
 ly another series of facts, relating to the eflects of Ihne 
 in the soil. 
 
 It is evident from the analysis of woody fibre by M. 
 M. Gay Lussac andThenard, (which shews that it con- 
 sists principally of the elements of water and carbon, the 
 carbon being in larger quantities than in the other vege- 
 table compounds) that any process which tends to ab- 
 stract carbonaceous matter from it, must bring it nearer 
 in composition to the soluble principles ; and this is done 
 in fermentation by the absorption of oxygene, and pro- 
 duction of carbonic acid ; and a similar cftect, it will be 
 shewn, is produced by lime. 
 
 Wood-ashes, imperfectly formed, that is, wpod-ashes 
 containing much charcoal, are said to have been used 
 with success as a manure. A part of their eflects may 
 be owing to the slow and gradual consumption of the 
 charcoal, which seems capable, under other circum- 
 stances than those of actual combustion, of absorbing 
 oxygene so as to become carl)onic acid. 
 
 In April, 1803, I enclosed some well- burnt charcoal 
 in a tube half filled with pure water, and half with com- 
 mon air; the tube was hermetically sealed, 1 opened 
 the tube under pure water, in the spring of 1804, at a 
 
mo 
 
 iiUie wlii'u iho iUiuospIio-iic. icnipoiaLiiie ami pleasure 
 wtue nrai ly the- sanlie as at the commencement of the ex- 
 periment. Some water rushed in ; and on expelling a 
 little air ])y heat from the tube, and analyzing it, it was 
 found to contain only seven percent, of oxygene. The 
 water in the tuhe, when mixed with lime-water, produ- 
 ced a copious precii>itate; so that carbonic acid had evi- 
 dently been formed and dissolved by tlie water. 
 
 Manures from animal substances, in general, require 
 no chemical preparation to fit them for the soil. The 
 greatobjectof the farmer is to blend them with the earthy 
 constituents in a proper state of division, and to prevent 
 their too rapid decompositioti. 
 
 The entire parts of the muscles of land animals are 
 not commonly used as manure, though there are many 
 cases in wliich such an application might be easily made. 
 Horses, dogs, sheep, deer, and other quadrupeds that 
 have died accidentally, or of disease, after their skins 
 arc separated, are often sullered to remain exposed to 
 the air, or immersed in water, till they are destroyed by 
 birds or beasts of prey, or entirely decomposed ; and in 
 this case, most of their organi/alde matter is lost for 
 the land in which they lie, and a considerable portion 
 of it employed in giving off noxious gases to the atmo- 
 sphere. 
 
 By covering dead animals with five or six times their 
 bulk of soil, mixed with one part of lime, and sutlering 
 them to remain for a few months ; their decomposition 
 would impregnate the soil with soluble matters, so as to 
 render it an excellent manure; and by mixing a little 
 fresh quick lime Avith it at the time of its removal, the 
 disagreeable ellluvia will be in a great measure destroy- 
 ed ; and it might be applied in the same way as any 
 other manure to crops. 
 
 Fiifh forms a powerful manure, in whatever state it 
 is applied ; but it cannot be ploughed in two fresii, though 
 the quantity should be limited. Mr. Young records an 
 experiment, in which herrings spread over a field, and 
 ploughed in for wheat, produced so rank a crop, that it 
 was entirely laid before harvest. 
 
 The refuse pilchards in Cornwall are used throughout 
 the county as a manure, with excellent effects. They 
 
are usually mixed with sand or soil, and sometimes w ith 
 sea weed, to prevent them from raising too luxuriant a 
 crop. The effects are perceived for several years. 
 
 In the fens of Lincolnshire, Cambridgeshire, and 
 Norfolk, the little fishjes called sticklebacks, are caught 
 in the shallow waters in such quantities, that they form 
 a great article of manure in the land bordering on the 
 fens. 
 
 It is easy to explain the operation of fish as a manure. 
 The skin is principally gelatine ; which from its slight 
 state of cohesion, is readily soluble in water : fat or oil 
 is always found in fishes, either under the skin or in 
 some of the viscera ; and their fibrous matter contains 
 all the essential elements of vegetable substances. 
 
 Amongst oily substances, blubber has been employed 
 as a manure. It is most useful when mixed with clay, 
 sand, or any common soil, so as to expose a large sur- 
 face to the air, the oxygene of which produces soluble 
 matter from it. Lord Somerville used blubber with 
 great success at his farm in Surrey. It was made into 
 a heap with soil, and retained its powers of fertilizing 
 for several successive years. 
 
 The carbon and hydrogene abounding in oily sub- 
 stances, fully account for their effects ; and their dura- 
 bility is easily explained from the gradual manner in 
 which they change by the action of air and water. 
 
 Bones are much used as a manure in the neighbour- 
 hood of London. After being broken, and boiled for 
 grease, they are sold to the farmer. The more divided 
 they are, the more powerful are their effects. The ex- 
 pense of grinding them in a mill would probably be re- 
 paid by the increase of their fertilizing powers ; and in 
 the state of powder they might be used in the drill Iius- 
 bandry, and delivered with the seed, in the same man- 
 ner as rape cake. 
 
 Bone dust, and bone shavings, the refuse of the turn- 
 ing manufacture, may be advantageously employed in 
 the same way. 
 
 The basis of Bone is constituted by earthy salts, prin- 
 cipally phosphate of lime, with some carbonate of lime 
 and phosphate of magnesia ; the easily decomposable 
 substances in bone are fat, gelatine, and cartilage, which 
 seems of the same nature as coagulated albumen. 
 
198 
 
 According to the analysis of Fourcroy and Vauqueiin, 
 ox bones are composed 
 
 Of decomposable animal matter - 51 
 
 — phosphate of lime . - - 37.7 
 
 — carbonate of lime - - - 10 
 
 — phosphate of Magnesia - - 1.3 
 
 100 
 
 M. Merat Guillot has given the following estimate of 
 the composition of the bones of different animals. 
 
 Bone of Calf 
 Horse 
 
 Sheep 
 
 Elk 
 
 Hog 
 
 Hare 
 
 Pullet 
 
 Pike 
 
 Carp 
 
 Horses' teeth 
 Ivory - - 
 
 Phosphate of l Carbonate of 
 Lime. Lime. 
 
 54 
 
 67.5 
 
 70 
 
 90 
 
 52 
 
 85 
 
 72 
 
 64 
 
 45 
 
 85.5 
 
 64 
 
 1.25 
 5 
 1 
 1 
 1 
 1.6 
 1 
 5 
 
 20.5 
 1 
 
 The remaining parts of the 100 must be considered 
 as decomposable animal matter. 
 
 Hoi^ is a still more powerful manure than bone, as 
 it contains a larger quantity of decomposable animal 
 matter. From 500 grains of ox horn, Mr. Hatchett ob- 
 tained only 1.5 grains of earthy residuum, and not quite 
 half of this was phosphate of lime. The shavings or 
 turnings of horn form an excellent manure, though they 
 are not suflBciently abundant to be in common use. The 
 animal matter in them seems to be of the nature of co- 
 agulated albumen, and it is slowly rendered soluble by 
 the action of water. The earthy matter in horn, and 
 still more that in bones, prevents the too rapid decom- 
 position of the animal matter, and renders it very dura- 
 ble in its effects. 
 
 Hair, woollen rags, and feathers are all analogous in 
 romposition, and principally consist of a substance simi- 
 
199 
 
 lar to albumen, united to gelatine. This is shewn by 
 the ingenious researches of Mr. Hatchett. The theory 
 of their operation is similar to that of bone and horn 
 shavings. 
 
 The refuse of the different manufactures of sHn and 
 leather form very useful manures ; such as the shavings 
 of the currier, furriers' clippings, and the offals of 
 the tan-yard, and of the glue- maker. The gelatine con- 
 tained in every kind of skin is in a state fitted for its 
 gradual solution or decomposition ; and when buried in 
 the soil, it lasts for a considerble time, and constantly 
 affords a supply of nutritive matter to the plants in its 
 neighbourhood. 
 
 Blood contains certain quantities of all the principles 
 found in other animal substances, and is consequently 
 a very good manure. It has been already stated that it 
 contains fibrine ; it likewise contains albumen : the red 
 particles in it which have been supposed by many fo- 
 reign chemists to be coloured by iron in a particular 
 state of combination with oxygene and acid matter, Mr. 
 Brande considers as formed of a peculiar animal sub- 
 stance, containing very little iron. 
 
 The scum taken from the boilers of the sugar bakers, 
 and which is used as manure, principally consists of 
 bullock's blood, which has been employed for the pur= 
 pose of separating the impurities of common brown su- 
 gar, by means of the coagulation of its albuminous mat» 
 ter by the heat of the boiler. 
 
 The different species oicoralsy coralines, and sponges f 
 must be considered as substances of animal origin. 
 From the analysis of Mr. Hatchett, it appears that all 
 these substances contain considerable quantities of a 
 matter analogous to coagulated albumen ; the sponges 
 afford likewise gelatine. 
 
 According to Merat Guillot, white coral contains 
 equal parts of animal matter and carbonate of lime ; red 
 coral 46.5 of animal matter, and 53.5 of carbonate of 
 lime ; articulated coraline 51 of animal matter, and 49 
 of carbonate of lime. 
 
 These substances are, I believe, never used as ma- 
 nure in this country, except in cases when they are ac- 
 cidently mixed with sea weed ; but it is probable that 
 
tlie coijilines might be advantageously employed, as they 
 are found in considerable quantity on the rocks, and bot- 
 toms of the rocky pools on many parts of our coast, 
 where the land gradually declines towards the sea; and 
 they might be detached by hoes, and collected without 
 much trouble. 
 
 Amongst excrementations, animal substances used as 
 manures, urine is the one upon which the greatest num- 
 ber of chemical experiments have been made, and the 
 nature of which is best understood. 
 
 The urine of the cow contains, according to the ex- 
 periments of Mr. Brande, 
 
 Water 65 
 
 Phosphate of lime - - - 3 
 
 Muriates of potassa and ammonia 15 
 
 Sulphate of potassa - - 6 
 
 Carbonates, potassa, and ammonia 4 
 
 Urea 4 
 
 The mint of the liorsc, according to Fouvcroy and 
 Yauquelin, contains, 
 
 Of Carbonate of lime - • 11 
 
 — Carbonate of soda - - 9 
 
 — J$enzoate of soda - - 24 
 
 — Muriate of potassa - - 9 
 
 — Urea - , . - 7 
 
 — Water and mucilage - - 940 
 
 In addition to these substances, Mr. Brande found in 
 it phosphate of lime. 
 
 The urine of the ass, the camel, the rabbit, and do- 
 mestic fowls have been submitted to diflerent experi- 
 ments, and their constitution iiave been found similar. 
 In tiu^ urine of the rabbit, in addition to most of tlic in- 
 gredients above mentioned, Vauquelin detected gelatine; 
 and tlie same chemist discovered uric acid in the urine 
 of domestic fowls. 
 
 Human urine contains a greater variety of constituents 
 thau any other species examined. 
 
 Urea, uric acid, and another acid similar to it in na- 
 ture called rosacic acid, acetic acid, albumen, gelatine, 
 a n:9inous matter, and various salts arc found in it. 
 
/■>,/. /;: 
 
 I'. L><l\ 
 
201 
 
 The human urine differs in composition according to 
 the state of the body, and the nature of the food and 
 drink made use of. In many cases of disease there is a 
 much larger quantity of gelatine and albumen than usual 
 in the urine ; and in diabetes it contains sugar. 
 
 It is probable that the urine of the same animal must 
 likewise differ according to the different nature of the 
 food and drink used ; and this will account for discordan- 
 cies in some of the analyses that have been published on 
 the subject. 
 
 Urine is very liable to change and to undergo the pu- 
 trefactive process ; and that of carnivorous animals more 
 rapidly than that of graminivorous animals. In proper-, 
 tion as there is more gelatine and albumen in urine, so 
 in proportion does it putrefy Aiore quickly. 
 
 The species of urine that contain most albumen, ge- 
 latine, and urea, are the best as manures ; and all urine 
 contains the essential elements of vegetables in a state 
 of solution. 
 
 During the putrefaction of urine the greatest part of 
 the soluble animal matter that it contains is destroyed ; 
 it should consequently be used as fresh as possible ; but 
 if not mixed with solid matter, it should be diluted with 
 water, as when pure it contains too large a quantity of 
 animal matter to form a proper fluid nourishment for ab- 
 sorption by the roots of plants. 
 
 Putrid urine abounds in ammoniacal salts ; and though 
 less active than fresh urine, is a very powerful manure. 
 
 According to a recent analysis published by Eerzcli- 
 us, 1000 parts of urine are composed of 
 
 Water 933 
 
 Urea - - - - - - 30.1 
 
 Uric acid . . . _ ± 
 
 Muriate of ammonia, free lactic ^ 
 
 acid, lactate of ammonia andC 17.14 
 animal matter " ' } 
 
 The remainder different salts, phosphates, sulphates, 
 and muriates. 
 
 Amongst excremenfitious solid substances used as ma- 
 nures, one of the most powerful is the dung of birds that 
 feed on animal food, particularly the dung of sea birds. 
 The guano, v/hich is used to a great extent in Scnth 
 
 c c 
 
202 
 
 America, and which is the manure which fertilizes the 
 sterile ])lains of Peru, is a production of this kind. It 
 exists abundantly, as we are informed byM. Humbolt, 
 on the small islands in the South Sea, at Chinche, Ilo; 
 Iza, and Arica. 50 vessels are laden with it annually 
 at Chinche, each of which carries from 1500 to 2000 cu- 
 bical feet. It is used as a manure only in very small 
 quantities ; and particularly for crops of maize. I made 
 some experiments on specimens of guano sent from South 
 America to the Board of Agriculture in 1805. It ap- 
 peared as a fine brown powder ; it blackened by heat, 
 and gave oft' strong ammoniacal fumes ; treated with ni- 
 tric acid it aflbrded uric acid. In 1806 M. M. Four- 
 croy and Yauquelin published an elaborate analysis of 
 guano. They state that i{ contains a fourth part of its 
 weight of uric acid, partly saturated with ammonia, and 
 partly with potassa ; some phosphoric acid combined 
 with the basis, and likewise with lime. Small quanti- 
 ties of sulphate and muriate of potassa, a little fatty 
 matter, and some quartzose sand. 
 
 It is easy to explain its fertilizing properties : from 
 its composition it might be supposed to be a very pow- 
 erful manure. It requires water for the solution of its 
 soluble matter to enable it to produce its full beneficial 
 effect on crops. * 
 
 The dung of sea birds has, I believe, never been used 
 as a manure in this country; butjt is probable, that even 
 the soil of the small islands on our coast much frequent- 
 ed by them, would fertilize. Some dung of sea birds 
 brought from a rock on the coast of Merionethshire, 
 produced a powerful but transient effect on grass. It 
 was tried, at my request, by Sir Robert Vaughan at 
 Nannau. 
 
 The rains in our climate must tend very much to in- 
 jure this species of manure, where it is exposed to them, 
 soon after its deposition ; but it may probably be found 
 in great perfection in caverns or clefts in rocks, haunt- 
 ed by cormorants and gulls. I examined some recent 
 cormorant's dung which I found on a rock near Cape Li- 
 zard in Cornwall. It had not at all the appearance of the 
 guano; was of a grayish white colour; had a very foe- 
 tid smell like that of putrid animal matter : when acted 
 
203 
 
 on by quicklime, it gave aljiindauce. of ammonia; treated 
 with nitric acid it yielded uric acid. 
 
 J\*ight soiU it is well Ichown, is a very powerful ma- 
 nure^ and. very liable to decompose. It differs in com- 
 position ; but always abounds in substances composed 
 of carbon, hydrogene, azote, and oxygene. From the 
 analysis of Borzelius, it appears that a part of it is al- 
 ways soluble in water ; and in whatever state it is used, 
 whether recent or fermented, it supplies abundance of 
 food to plants. 
 
 The disagreeable smell of night soil maybe destroy- 
 ed by mixing it with quicklime ; and if exposed to the 
 atmosphere in thin layers strewed over with quicklime 
 in fine weather, it speedily dries, is easily pulverised, 
 and in this state may be used in the same manner as 
 rape cake, and delivered into the furrow with the seed. 
 
 The Chinese, who have more practical knowledge of 
 the use and application of manares than any other peo- 
 ple existing, mix their night soil with one-third of its 
 weight of a fat marie, make it into cakes, and dry it by 
 exposure to the sun. These cakes, we are informed 
 by the French missionaries, have no disagreeable smell, 
 and form a common article of commerce of the em- 
 pire. 
 
 The earth, by its absorbent powers, probably prevents, 
 to a certain extent, the action of moisture upon the dung, 
 and likewise defends it from the ejttects of air. 
 
 After night soil, pigeons^ dung comes next in order, 
 as to fertilizing power. I digested 100 grains of pi- 
 geons' dung, in hot water for some hours, and obtained 
 from it 23 grains of soluble matter; which afforded abun- 
 dance of carbonate of ammonia by distillation ; and left 
 carbonaceous matter, saline matter principally common 
 salt, and carbonate of lime as a residuum. Pigeons' 
 dung when moist readily ferments, and after a fermenta- 
 tion contains less soluble matter than before : from 100 
 parts of fermented pigeons' dung, 1 obtained only eight 
 parts of soluble matter, which gave proportionally less 
 carbonate of ammonia in distillation than recent pigeons' 
 dung. 
 
 It is evident tliat this manure should be applied as 
 new as possible ; and when dry, it may be employed in 
 
2U4 
 [|K' hame niiimiicr us the other miiuures papabie of being 
 
 The soil in woods where great flocks of wood-pigeons 
 roost, is often highly impregnated with their dung, and 
 it cannot be doubted, would form a valuable manure. 
 I have found such soil yield ammonia when distilled 
 with lime. In the winter likewise it usually contains 
 abundance of vegetable matter, the remains of decayed 
 leaves ; and the dung tends to bring the vegetable mat- 
 ter into a state of solution. 
 
 The dung of domestic fowls approaches very nearly 
 in its nature to pigeons' dung. Uric acid has been found 
 in it. It gives carbonate of ammonia by distillation, and 
 immediately yields soluble matter to water. It is very 
 liable to ferment. 
 
 The dung of fowls is employed in common with that 
 of pigeons by tanners to bring on a slight degree of pu- 
 trefaction in skins that are to be used for making soft 
 leather ; for this purpose the dung is diffused through 
 water. In this state it rapidly undergoes putrefaction, 
 and brings on a similar change in the skin. The ex- 
 crements of dogs are employed by the tanner with simi- 
 lar eliects. In all cases, the contents of i\\^ grainer, as 
 the pit is called in which soft skins are prepared by dung, 
 must form a very useful manure. 
 
 Rabbits^ dung has never been analysed. It is used 
 with great success a^ a manure by Mr. Fane, who finds 
 it profitable to keep rabbits in such a manner as to pre- 
 serve their dung. It is laid on as fresh as possible, and 
 is found better the less it has fermented. 
 
 The dung of cattle^ oxen^ and cows, has been chemi- 
 cally examined by M. M. Einhof and Thaer. They 
 found that it contained matter soluble in water; and that 
 it gave in fermentation nearly the same products as ve- 
 getable substances, absorbing oxygene and producing 
 carbonic acid gas. 
 
 The recent dung of sheep, and of deer, afford, when 
 long boiled in water, soluble matters, which equal from 
 two to three per cent, of their weights I have examin- 
 ed these soluble substances procured- by solution and 
 evaporation ; they contain a very small quantity of mat- 
 ter analogous to animal mucus ; and are principally com- 
 
205 
 
 posed of a bitter extract, soluble both in water and in 
 alcohol. They give ammoniacal fumes by distillation ; 
 and appear very little in composition. 
 
 I watered some blades of grass for several successive 
 days with a solution of these extracts ; they evidently be- 
 came greener in consequence, and grew more vigorously 
 thangrass in otlier respects, under the same circumstances. 
 
 Ilie part of the dung of cattle, slieep, and deer, not 
 soluble in water, appears to be mere woody fibre, and 
 precisely analogous to the residuum of those vegetables 
 that form their food after they have been deprived of all 
 their soluble materials. 
 
 The dung of horses gives a brown fluid, which when 
 evaporated, yields a bitter extract, which affords ammo- 
 niacal fumes more copiously than that from the dung of 
 oxen. 
 
 If the pure dung of cattle is to be used as manure, 
 like the other species of dung which have been men- 
 tioned, there seems no reason why it should be made to 
 ferment except in the soil ; or if suffered to ferment, it 
 should be only in a very slight degree. The grass in 
 the neighbourhood of recently voided dung, is always 
 coarse and dark green ; some persons have attributed this 
 to a noxious quality in unfermenting dung ; but it seems 
 to be rather the result of an excess of food furnislied to 
 the plants. 
 
 The question of the proper mode of the application 
 of the dung of horses and cattle, however, properly be- 
 longs to the subject of composite manures^ for it is 
 usually mixed in the farm-yard with straw, offal, chafl', 
 and various kind of litter; and itself contains a large 
 proportion of fibrous vegetable matter. 
 
 A slight incipient fermentation is undoubtedly of use 
 in the dunghill ; for by means of it a disposition is 
 brought on in the woody fibre to decay and dissolve, 
 when it is carried to the land, or ploughed into the soil ; 
 and woody fibre is always in great excess in the refuse 
 of the farm. 
 
 Too great a degree of fermentation is, however, very 
 prejudicial to the composite manure in the dunghill ; it 
 is better that there should be no fermentation at all be- 
 fore the manure is used, than that it should be carried 
 
206 
 
 too far. This must be obvious from what has been al- 
 ready stated iu this Lecture. The excess of feriaenta- 
 tion tends to the destruction and dissipation of the most 
 useful part of the manure ; and the ultimate results of 
 this process are like those of combustion. 
 
 It is a common practice amongst farmers to suffer the 
 farm-yard dung to ferment till the fibrous texture of the 
 vegetable matter is entirely broken down ; and till the 
 manure becomes perfectly cold, and so soft as to be easily 
 cut by the spade. 
 
 Independent of the general theoretical views unfa- 
 vourable to this practice, founded upon the nature and 
 composition of vegetable substances, there are many ar- 
 guments and facts which shew that it is prejudicial to 
 the interests of the farmer. 
 
 During the violent fermentation wliicli is necessary 
 for reducing farm-yard manure to the state in which it is 
 called short miicTc^ not only a large quantity of fluid, 
 but likewise of gaseous matter, is lost ; so much so, that 
 the dung is reduced one half, or two thirds in weight ; 
 and the principal elastic matter disengaged, in carbonic 
 acid with some ammonia ; and both these, if retained 
 by the moisture in the soil, as has been stated before, 
 are capable of becoming a useful nourishment of plants. 
 
 In October, 1808, I filled a large retort capable of 
 containing three pints of water, with some hot ferment- 
 ing manure, consisting principally of the litter and dung 
 of cattle ; I adapted a small receiver to the retort, and 
 connected the whole with a mercurial pneumatic appa- 
 ratus, so as to collect the condensible and elastic fluids 
 which might rise from tlie dung. The receiver soon 
 became lined with dew, and drops began in a few hours 
 to trickle down the sides of it. Elastic fluid likewise 
 was generated ; in three days thirty-five cubical inches 
 had been formed, which, when analyzed, were found 
 to contain twenty-one cubical inches of carbonic acid, 
 the remainder was hydrocarbonate mixed with some 
 azote, probably no more than existed in the common 
 air iu the receiver. The fluid matter collected in the 
 receiver at tike same time amounted to nearly half an 
 ounce. It had a saline taste, and a disagreeable smell, 
 and contained some acetate and carbonate of ammonia. 
 
207 
 
 Finding such products given off from fermenting lit- 
 ter, I introduced the heak of another retort filled with 
 similar dung very hot at the time, in the soil amongst 
 the roots of some grass in the border of a garden ; in 
 less than a week a very distinct effect was produced on 
 the grass ; upon the spot exposed to the influence of the 
 matter disengaged in fermentation, it grew with much 
 more luxuriance than the grass in any other part of the 
 garden. 
 
 Besides the dissipation of gaseous matter when fer- 
 mentation is pushed to the extreme, there is another dis- 
 advantage in the loss of heat, which, if excited in the 
 soil, is useful in promoting the germination of the seed, 
 and in assisting the plant in the first stage of its growth, 
 when it is most feeble and most liable to disease : and 
 the fermentation of manure in the soil must be particu- 
 larly favourable to the wheat crop in preserving a genial 
 temperature beneath the surface late in autumn, and du- 
 ring winter. 
 
 Again, it is a general principle in chemistry, that in 
 all cases of decomposition, substances combine much 
 more readily at the moment of their disengagement, 
 than after they have been perfectly formed. And in 
 fermentation beneath the soil the fluid matter produced 
 is applied instantly, even whilst it is warm, to the or- 
 gans of the plant, and consequently is more likely to be 
 efficient, than in manure that has gone through the pro- 
 cess ; and of which all the principles have entered into 
 new combinations. 
 
 In the writings of scientific agriculturists, a great mass 
 of facts may be found in favour of the application of 
 farm-yard dung in a recent state. Mr. Young, in the 
 Essay on Manures, which I have already quoted, ad- 
 duces a number of excellent authorities in support of 
 the plan. Many, who doubted, have been lately con- 
 vinced ; and perhaps there is no subject of investigation 
 in which there is such a union of theoretical and prac- 
 tical evidence. I have myself, within the last ten years, 
 witnessed a number of distinct proofs on the subject. I 
 shall content myself with quoting that which ought to 
 have, and which I am sure will have, the greatest weight 
 amongst agriculturists. Within the last seven years Mr, 
 
208 
 
 Coke has entirely given up the system formerly adopted 
 on his farm, of applying fermented dung; and he in- 
 forms me, that his crops have been since as good as they 
 ever were, and that his manure goes nearly twice as far. 
 
 A great objection against slightly fermented dung is, 
 that weeds spring up more luxuriantly where it is applied. 
 If there are seeds carried out in the dung they certainly 
 will germinate ; but it is seldom that this can be the 
 case to any extent ; and if the land is not cleansed of 
 weeds, any kind of manure fermented or unfermented 
 will occasion their rapid growth. If slightly fermented 
 farm-yard dung is used as a top dressing for pastures, 
 the long straws and unfermented vegetable matter re- 
 maining on the surface should be removed as soon as the 
 grass begins to rise vigorously, by raking, and carried 
 back to the dunghill : in this case no manure will be 
 lost, and the husbandry will be at once clean and eco- 
 nomical. 
 
 In cases when farm-yard dung cannot be immediate- 
 ly applied to crops, the destructive fermentation of it 
 should be prevented as much as possible ; the principles 
 on which this may be effected have been already allu- 
 ded to. 
 
 The surface should be defended as much as possible 
 from the oxygene of the atmosphere ; a compact marie, 
 or a tenacious clay, offers the best protection against the 
 air ; and before the dung is covered over, or, as it were, 
 sealed up, it should be dried as much as possible. If 
 the dung is found at any time to heat strongly, it should 
 be turned over, and cooled by exposure to air. 
 
 Watering dunghills is sometimes recommended for 
 checking the progress of fermentation ; but this practice 
 is inconsistent with just chemical views. It may cool 
 the dung for a short time ; but moisture, as I have be- 
 fore stated, is a principal agent in all processes of de- 
 composition. Dry fibrous matter will never ferment. 
 Water is as necessary as air to the process ; and to sup- 
 ply it to fermenting dung, is to supply an agent which 
 will hasten its decay. 
 
 In all cases when dung is fermenting, there are sim- 
 ple tests by which the rapidity of the process, and con- 
 2«c«iuently the injury done, may be discovered. 
 
209 
 
 If a thermometer plunged into the dung does not rise 
 to above 100 degrees of Fahrenheit, there is little dan- 
 ger of much aeriform matter flying off. If the tempe- 
 rature is higher, the dung should be immediately spread 
 abroad. 
 
 When a piece of paper moistened in muriatic acid 
 held over the steams arising from a dunghill gives dense 
 fumes, it is a certain test that the decomposition is go- 
 ing too far, for this indicates that volatile alkali is dis- 
 engaged. 
 
 When dung is to be preserved for any time, the si- 
 tuation in which it is kept is of importance. It should, 
 if possible, be defended from the sun. To preserve it 
 under sheds would be of great use ; or to make the site 
 of a dunghill on the north side of a wall. The floor 
 on which the dung is heaped, should if possible, be pa- 
 ved with flat stones ; and there should be a little incli- 
 nation from each side towards the centre, in whicli there 
 should be drains connected with a small well, furnished 
 with a pump, by which any fluid matter may be col- 
 lected for the use of the land. It too often happens 
 that a (dense mucilaginous and extractive fluid is suffer- 
 ed to drain away from the dunghill, so as to be entirely 
 lost to the farm. 
 
 Street and road dung, and the sweepings of houses, 
 may be all regarded as composite manures : the consti- 
 tution of them is necessarily various, as they are deri- 
 ved from a number of different substances. These ma- 
 nures are usually applied in a proper manner, without 
 being fermented. 
 
 Soot, which is principally formed from the combus- 
 tion of pit-coal or coal, generally contains likewise sub- 
 stances derived from animal matters. This is a very 
 powerful manure. It affords ammoniacal salts by dis- 
 tillation, and yields a brown extract to hot water, of a 
 bitter taste. It likewise contains an-empyreumatic oiL 
 Its great basis is charcoal, in a state in which it is ca- 
 pable of being rendered soluble by the action of oxy- 
 gene and water. 
 
 This manure is well fitted to be used in the dry state, 
 thrown into the ground with the seed, and requires no 
 preparation, 
 
 Bd 
 
210 
 
 Till'- doctrine of the proper application of nmiiurey 
 from orj:;;iiiis(',<l wiibstanceH, ollVrs an illnstialiou of an 
 important part of the, oi(,on(nny of nature, and of the 
 liappy order in wliicli it is arranej^cd. 
 
 '^I'lie di'Mtli Mtid decay of animal substances lend to 
 resolve ori^aniscd forms into cliemical constituents ; and 
 the pernicious ellluvia diseni!;ai;ed in the process seem 
 to point out the, pnjpriety of buryinjj; them in the soil, 
 where they are fitted tu hecom(j the food of vei:;etables. 
 'i'he fermentation and putrefaction of organised sub- 
 stances in the free atmosphere are noxious processes ; 
 beneath the surface of tiie ground they are salutary 
 operati(uis. In this case the food of ])lants is prepared 
 where it < .'in ]»e used ; and that which would oiVend the 
 senses and injure the, lu-alth, if exposed, is converted 
 by gradual processes into forms of beauty and of use- 
 fulness ; the fo'tid gas is rendered a constituent of the 
 aroma of the ilower, and what might be poison, becomes 
 nourishment to animals and to man. 
 
On Munurp.8 of mineral Orii^in, or fosmln ManmuiH ; 
 their Preparation, and the Mwnncr in which thai/ 
 Act. Of Lime in ita dijf'erent State a ; Opej'ution of 
 Lime as a Manure and, a Cement ; different Comt)i- 
 nations of Lime. Of Gyfisum. ; Ideas respectini:; its 
 Use. Of other JS'eiitro- saline domponnds, emjitoijed, 
 us Manures. Of Alkalies and at k aline Salts; (f 
 Commjm Salt. 
 
 JL HE whole tenor oi' fJie precediui; lieclnrcH shew.s^ 
 that a £;reat variety of suhstaiices (;oiitriljute,.s to the 
 growth of plants, and supplies the materials of their 
 riourislimcnt. The conversion of matter that has he- 
 longed to living structures into organised forms is a pro- 
 cess that can he easily understoorl ; hut it is more dif- 
 iicult to foih>w those operations hy which earthy and 
 saline matters are consolidated in the iihre of plants, 
 and hy which they are made- snhservient to their func- 
 tions. Some inquirers adopting that suhlirnc. generali- 
 zation of the ancient philosophers, that matter is the 
 same in essence, and that the dillcntnt suhstances con- 
 sidered as e.lements hy chemists, are merely diil'erent 
 arrangements of the same indeslruf^tihie particles, have 
 endeavoured to prove, that all the vari(5(.ies of the prin- 
 cijdes found in plants, may he formed from the suhstan- 
 ces in the atmosphere; and that vegcitahh*. life is a pro- 
 cess in which hodies that the analytical philosopher is 
 unahle to change or to form, are ccmstantly com[»osed 
 and decomposed. These opinions have not heen ad- 
 vanced merely as hypotheses; attempts have heen made 
 to supj)ort them i>y experiments. M. Hchra-dar and 
 Mr. J5raconnet, from a series of distinct investigations, 
 have arrived at the same conclusions. They stale that 
 difl'erent seeds sown in fine sand, sulphur, and metallic 
 oxides, and supplied only with atmospherical air and 
 ■water, produced ln'.althy plants, which hy analysis 
 
*i I 'i 
 
 yielded various earthy and saline matters, Avliich eiiliei* 
 were not contained in the seeds, or the material in whicli 
 they grew ; or which were contained only in much 
 smaller quantities in the seeds : and hence they conclude 
 that they must have ])een formed from air or water, in 
 consequence of the agencies of the living organs of the 
 plant. 
 
 The researches of these two gentlemen were conduct- 
 ed with much ingenuity and address ; but there were cir- 
 cumstances which interfered with their results, which 
 they could not have known, as at the time their labours 
 were published they had not been investigated. 
 
 I have found that common distilled water is iar from, 
 being free from saline impregnations. In analysing it 
 by Voltaic electricity, I procured from it alkalies and 
 earths ; and many of the combinations of metals with 
 chlorine are extremely volatile substances. When dis- 
 tilled water is supplied in an unlimited manner to plants, 
 it may furnish to them a number of difterent substances, 
 which though in quantities scarcely perceptible in the 
 water, may accumulate in the plant, which probably per- 
 spires only absolutely pure water. 
 
 In 1801, I made an experiment on the growth of oats, 
 supplied with a limited quantity of distilled water in a 
 soil composed of pure carbonate of lime. The soil and 
 the water were placed in a vessel of iron, which was in- 
 cluded in a large jar, connected with the free atmosphere 
 by a tube, so curved as to prevent the possibility of any 
 dust, or fluid, or solid matter from entering into the jar. 
 My object was to ascertain whether any siliceous earth 
 would be formed in the process of Vegetation ; but the 
 oats grew very feebly, and began to be yellow before 
 any flowers formed : the entire plants were burnt, and 
 their ashes compared with those from an equal number 
 of grains of oats. Less silicious earth was given by the 
 plants than by the grains ; but their ashes yielded much 
 more carbonate of lime. That there was less siliceous 
 earth I attribute to the circumstance of the husk of the 
 oat being thrown oft* in germination ; and this is the part 
 which most abounds in silica. Healthy green oats taken 
 from a growing crop, in a field of which the soil was a 
 fine sand, yielded siliceous earth in a much gieater pro- 
 
'il3 
 
 portion than au equal weight of the corn artificially 
 raised. 
 
 The general results of this experiment are very much 
 opposed to the idea of the composition of the earths, by 
 plants, from any of the elements found in the atmo- 
 sphere, or in water ; and there are other facts contra- 
 dictory to the idea. Jacquin states that the ashes of glass 
 wort {Salsola soda,) when it grows in inland situations, 
 afford the vegetable alkali ; when it grows on the sea v 
 shore, where compounds which afford the fossile or ma- 
 rine alkali are more abundant, it yields that substance. 
 Du Hamel found, that plants which usually grow on the 
 sea shore, made small progress when planted in soils 
 containing little common salt. The sunflower, when 
 growing in lands containing no nitre, does not afford 
 that substance ; though when watered by a solution of 
 nitre, it yields nitre abundantly. The tables of de Saus- 
 sure, referred to in the Third Lecture, shew that the 
 ashes of plants are similar in constitution to the soils in 
 which they have vegetated. 
 
 De Saussure made plants grow in solutions of differ- 
 ent salts, and he ascertained, that in all cases, certain 
 portions of the salts were absorbed by the plant, and 
 found unaltered in their organs. 
 
 Even animals do not appear to possess the power of 
 forming the alkaline and earthy substances. Dr. For- 
 dyce found, that when canary birds, at the time they 
 were laying eggs, were deprived of access to carbonate 
 of lime, their eggs had soft shells ; and if there is any 
 process for which nature ma^be conceived most likely 
 to supply resources of this kind, it is that connected with 
 the reproduction of the species. 
 
 As the evidence on the subject now stands, it seems 
 fair to conclude, that the different earths and saline sub- 
 stances found in the organs of plants are supplied by 
 the soils in which they grow ; and in no cases composed 
 by new arrangements of the elements in air or water. 
 What may be our ultimate view of the laws of chemis- 
 try, or how far our ideas of elementary principles may 
 be simplified, it is impossible to say. We can only rea- 
 son from facts. We cannot imitate the powers of com- 
 position belonging to vegetable structures ; but at least 
 
we can understand them : and as far as our researches 
 have gone, it appears, that in vegetation coin|)ound 
 forms are uniformly produced from simpler ones ; and 
 the elements in the soil, the atmosphere, and the earth 
 absorbed and made parts of beautiful and diversified 
 structures. 
 
 The views which have been just developed lead to 
 correct ideas of the operation of these manures which 
 are not necessarily the result of decayed organised bo- 
 dies, and which are not composed of different propor- 
 tions of carbon, hydrogene, oxygene, and azote. — They 
 must produce their effect, either by becoming a constitu- 
 ent part of the plant, or by acting upon its more essen- 
 tial food, so as to render it more fitted for the purposes 
 of vegetable life. 
 
 The only substances which can with propriety be 
 called fossile manures, and which are found unmixed 
 with the remains of any organised beings, are certain 
 alkaline earths or alkalies, and their combinations. 
 
 The only alkaline earths which have been hitherto 
 applied in this way, are lime and magnesia. Potassa 
 and soda, the two fixed alkalies, are both used in certain 
 of their chemical compounds. I shall state in succession 
 such facts as have come to my knowledge respecting 
 each of these bodies in their applications to the purposes 
 of agriculture ; but I shall enlarge most upon the sub- 
 ject of lime ; and if I should enter into some details 
 which may be tedious and minute, I trust, my excuse 
 will be found in the importance of the inquiry ; and it 
 is one which has been greatly elucidated by late disco- 
 veries. 
 
 The most common form in which lime is found on 
 the surface of the earth, is in a state of combination 
 with carbonic acid or fixed air. If a piece of lime- 
 stone, or chalk, be thrown into a fluid acid, there will 
 be an effervescence. This is owing to the escape of 
 the carbonic acid gas. The lime becomes dissolved in 
 the liquor. 
 
 When limestone is strongly heated, the carbonic acid 
 gas is expelled, and then nothing remains but the pure 
 alkaline earth ; in this case there is a loss of weight ; 
 and if the fire has been very high, it approaches to one- 
 
:ii5 
 
 half the weight of the stone ; but iii comuiou cases, iime- 
 stones, if well dried before burning, do not lose much 
 more than from 35 to 40 per cent., or from seven to eight 
 parts out of twenty. 
 
 I mentioned, in discussing the agencies of the atmo- 
 sphere upon vegetables, in the beginning of the Fifth 
 Lecture, that air always contains carbonic acid gas, and 
 that lime is precipitated from water by this substance. 
 When burnt lime is exposed to the atmosphere, in a cer- 
 tain time it becomes mild, and is the same substance as 
 that precipitated from lime water ; it is combined with 
 carbonic acid gas. Quicklime, when fi^'t made, is caustic 
 and burning to the tongue, renders vegetable blues 
 green, and is soluble in water; but when combined with 
 carbonic acid it looses all these properties, its solubili- 
 ty and its taste : it regains its power of effervescing, and 
 becomes the same chemical substance as chalk, or lime- 
 stone. 
 
 Very few limestones, or chalks, consist entirely of 
 lime and carbonic acid. The statuary marbles, or cer- 
 tain of the rhomboidal spars, are almost the only pure 
 species ; and the different properties of limestones, both 
 as manures and cements, depend upon the nature of the 
 ingi'edients mixed in the limestone ; for the true calca- 
 reous clement, the carbonate of lime, is uniformly the 
 same in nature, properties, and effects, and consists of 
 one proportion of carbonic acid 41.4, and one of lime 
 55. 
 
 When a limestone does not copiously effervesce in 
 acids, and is sufficiently hard to scratch glass, it contains 
 siliceous, and probably aluminous earth. When it is 
 deep brown, or red, or strongly coloured of any of the 
 shades of brown or yellow, it contains oxide of iron. 
 When it is not sufficiently hard to scratch glass, but ef- 
 fervesces slowly, and makes the acid in which it effer- 
 vesces milky, it contains magnesia. And when it is black, 
 and emits a foetid smell if rubbed, it contains coaly or 
 bituminous matter. 
 
 The analysis of limestones is not a difficult matter ; 
 and the proportions of their constituent parts may be ea- 
 sily ascertained, by the processes described in the Lec- 
 ture on the Analysis of Soils ; and usually with suffi- 
 
216 
 
 cient accuracy for all the purposes of the farmer, by the 
 fifth process. 
 
 Before any opinion can be formed of the manner in 
 which the different ingredients in limestone modify their 
 properties, it will be necessary to consider the operation 
 of the pure calcareous element as a manure, and as a 
 cement. 
 
 Quicklime in its pure state, whether in powder, or 
 dissolved in water, is injurious to plants. — I have in se- 
 veral instances killed grass by watering it with lime wa- 
 ter. — But lime, in its state of combination with carbonic 
 acid, as is evident from the analyses given in the Fourth 
 Lecture, is a useful ingredient in soils. Calcareous 
 earth is found in the ashes of the greater number of 
 plants ; and exposed to the air, lime cannot long conti- 
 nue caustic, for the reasons that were just now assign- 
 ed, but soon becomes united to carbonic acid. 
 
 When newly burnt lime is exposed to air, it soon falls 
 into powder ; in this case it is called slacked lime ; and 
 the same effect is immediately produced by throwing wa- 
 ter upon it, when it heats violently, and the water dis- 
 appears. 
 
 Slacked lime is merely a combination of lime, with 
 about one third of its weight of water ; i. e. fifty-five 
 parts of lime absorb seventeen parts of water ; and in 
 this case it is composed of a definite proportion of wa- 
 ter, and is called by chemists hydrate of lime ; and when 
 hydrate of lime becomes carbonate of lime by long ex- 
 posure to air, the water is expelled, and the carbonic 
 acid gas takes its place. 
 
 When lime, whether freshly burnt or slacked, is mix- 
 ed with any moist fibrous vegetable matter, there is a 
 strong action between the lime and the vegetable mat- 
 ter, and they form a kind of compost together of which 
 a part is usually soluble in water. 
 
 By this kind of operation, lime renders matter which 
 was before comparatively inert, nutritive ; and as char- 
 coal and oxygene abound in all vegetable matters, it 
 becomes at the same time converted into carbonate of 
 lime. 
 
 Mild lime, powdered limestone, marles, or chalks, 
 have no action of this kind upon vegetable matter ; by 
 
217 
 
 their action they prevent the too rapid decomposition of 
 substances already dissolved ; but they have no tenden- 
 cy to form soluble matters. 
 
 It is obvious from these circumstances, that the ope- 
 ration of quicklime, and marie or chalk, depends upon 
 principles altogether different. — Quicklime in being ap- 
 plied to land, tends to bring any hard vegetable matter 
 that it contains into a state of more rapid decomposition 
 and solution, so as to render it a proper food for plants. 
 — Chalk and marie, or carbonate of lime, will only im- 
 prove the texture of the soil, or its relation to absorp- 
 tion ; it acts merely as one of its earthy ingredients.—- 
 Quicklime, when it becomes mild, operates in the same 
 manner as chalk ; but in the act of becoming mild, it 
 prepares soluble out of insoluble matter. 
 
 li is upon this circumstance that the operation of lime 
 in the preparation of wheat crops depends ; and its ef- 
 ficacy in fertilizing peats, and in bringing into a state of 
 cultivation all soils abounding in hard roots or dry fibres, 
 or inert vegetable matter. 
 
 The solution of the question whether quicklime ought 
 to be applied to a soil, depends upon the quantity of in- 
 ert vegetable matter that it contains. The solution of 
 the question, whether marie, mild lime, or powdered 
 limestone, ought to be applied, depends upon the quan- 
 tity of calcareous matter already in the soil. All soils 
 are improved by mild lime, and ultimately by quicklime, 
 which do not effervesce with acids ; and sands more than 
 clays. 
 
 When a soil deficient in calcareous matter contains 
 much soluble vegetable manure, the application of quick- 
 lime should always be avoided, as it either tends to de- 
 compose the soluble matters by uniting to their carbon 
 and oxygeue so as to become mild lime, or it combines 
 withjthe soluble matters, and forms compounds having 
 less attraction for water than the pure vegetable sub- 
 stance. 
 
 The case is the same with respect to most animal 
 manures ; but the operation of the lime is different in 
 different cases, and depends upon the nature of the ani- 
 mal matter. Lime forms a kind of insoluble soap with 
 oily matters, and then gradually decomposes them by 
 
 E e 
 
3(8 
 
 separating from them oxygene and carbon. It combines 
 likewise with the animal acids, and probably assists 
 their decomposition by abstracting carbonaceous matter 
 from them combined with oxy£;ene ; and, consequently, 
 it must render them less nutritive. It tends to diminish 
 likewise the nutritive powers of albumen from the same 
 causes ; and always destroys, to a certain extent, the 
 efficacy of animal manures, either by combining with 
 certain of their elements, or by giving to them new ar- 
 rangements. Lime should never be applied with ani- 
 mal manures, unless they are too rich, or for the pur- 
 pose of preventing noxious effluvia, as in certain cases 
 mentioned in the last Lecture. It is injurious when mix- 
 ed with any common dung, and tends to render the ex- 
 tractive matter insoluble. 
 
 I made an experiment on this subject: I mixed a 
 quantity of brown soluble extract, which was procured 
 from sheeps' dung with five times its weight of quick- 
 lime. I then moistened them with water ; the mixture 
 heated very much ; it was suft'ered to remain for four- 
 teen hours, and was then acted on by six or seven times 
 its bulk of pure water : the water, after being passed 
 through a filtre, was evaporated to dryness ; the solid 
 matter obtained was scarcely coloured, and was lime 
 mixed with a little saline matter. 
 
 In those cases in which fermentation is useful to pro- 
 duce nutriment from vegetable substances, lime is always 
 efficacious. I mixed some moist tanner's spent bark with 
 one-fifth of its weight of quicklime, and suffered them 
 to remain together in a close vessel for three months ; 
 the lime had become coloured, and was effervescent : 
 when water was boiled upon the mixture, it gained a 
 tint of fawn colour, and by evaporation furnished a fawn- 
 coloured powder, which must have consisted of lime 
 united to vegetable matter, for it burnt when strongly 
 heated, and left a residuum of mild lime. 
 
 The limestones containing alumina and silica are less 
 fitted for the purposes of manure than pure limestones ; 
 but the lime formed from them has no noxious quality. 
 Such stones are less efficacious, merely because they fur- 
 nish a smaller quantity of quicklime. 
 
 I mentioned bituminous limestones. There is very 
 
2tt> 
 
 seldom any considerable portion of coaly matter in these 
 stones ; never as much as five parts in 100 ; but such 
 limestones make very good lime. The carbonaceous 
 matter can do no injury to the Land, and may^ under 
 certain circumstances, become a food of the plant, as is 
 evident from what was stated in the last Lecture. 
 
 The subject of the application of the magnesian lime- 
 stone is one of great interest. 
 
 It had been long known to farmers in the neighbour- 
 hood of Doncaster, that lime made from a certain lime- 
 stone applied to the land, often injured tlie crops con- 
 siderably, as I mentioned in the introductory Lecture. 
 Mr. Tennant, in making a series of experiments upon 
 this peculiar calcareous substance, found that it contain- 
 ed magnesia ; and on mixing some calcined magnesia 
 with soil, in which he sowed different seeds, he found 
 that they either died, or vegetated in a very imperfect 
 manner, and the plants were never healthy. And with 
 great justice and ingenuity he referred the bad effects 
 of the peculiar limestone to the magnesian earth it con- 
 tains. 
 
 In making some inquiries concerning this subject, I 
 found that there were cases in which this magnesian 
 limestone was used with good effect. 
 
 Amongst some specimens of limestone which Lord 
 Somerville put into my hands, two marked as peculiar- 
 ly good proved to be magnesian limestones. And lime 
 made from the JBreedon limestone is used in Leicester- 
 shire, where it is called hot lime ; and 1 have been in- 
 formed by farmers in the neighbourhood of the quarry, 
 that they employ it advantageously in small quantities, 
 seldom more than 25 or 30 bushels to the acre. And 
 that they find it may be used with good effect in larger 
 quantities, upon rich land. 
 
 A minute chemical consideration of this question will 
 lead to its solution. 
 
 Magnesia has a much weaker attraction for carbonic 
 acid than lime, and will remain in the state of caustic 
 or calcined magnesia for many months, though exposed 
 to the air. And as long as any caustic lime remains, 
 the magnesia cannot be combined with carbonic acid, 
 for lime instantly attracts carbonic acid from magnesia. 
 
220 
 
 Wlieu a magnesian limestone, is burnt, the magnesia 
 is deprived of carbonic acid much sooner than the lime ; 
 and if there is not much vegetable or animal matter in 
 the soil to supply by its decomposition carbonic acid, 
 the magnesia will remain for a long time in the caustic 
 state ; and in this state acts as a poison to certain vege- 
 tables. And that more magnesian lime may be used 
 upon rich soils, seems to be owing to the circumstance^ 
 that the decomposition of the manure in them supplies 
 carbonic acid. And magnesia in its mild state, i. e. 
 fully combined with carbonic acid, seems to be always 
 a useful constituent of soils. I have thrown carbon- 
 ate of magnesia (procured by boiling the solution of mag- 
 nesia in super-carbonate of potassa) upon grass, and 
 upon growing ^\'heat and barley, so as to render the sur- 
 face white; but the vegetation was not injured in the 
 slightest degree. And one of the most fertile parts of 
 Cornwall, the Lizard, is a district in which the soil con- 
 tains mild magnesian earth. 
 
 The Lizard Downs bear a short and green grass, 
 which feeds sheep producing excellent mutton ; and the 
 cultivated parts are amongst the best corn lands in the 
 county. 
 
 Thjrt the theory which I have ventured to give of the 
 operation of magnesian lime is not unfounded, is shewn 
 by an experiment which 1 made expressly for the pur- 
 pose of determining the true nature of the operation of 
 this substance. I took four portions of the same soil : 
 with one 1 mixed ^V of its weight of caustic magnesia, 
 with another I mixed the same quantity of magnesia 
 and a proportion of a fat decomposing peat equal to one- 
 fourth of the weight of the soil. One portion of soil re- 
 mained in its natural state ; and another was mixed with 
 peat without magnesia. The mixtures were made in De- 
 cember 1806 ; and in April 1807, barley was sown ia 
 all of them. It grew very well in the pure soil, but bet- 
 ter in the soil containing the magnesia and peat ; and 
 nearly as well in the soil containing peat alone : but in 
 the soil containing the magnesia alone, it rose very 
 feeble, and looked yellow and sickly. 
 
 1 repeated this experiment in the summer of 1810 with 
 similar results ; and I found that the magnesia in the 
 
221 
 
 soil mixed with peat became strongly eftervescent; 
 whilst the portion in the unmixed soil gave carbonic 
 acid in much smaller quantities. In the one case the 
 magnesia had assisted in the formation of a manure, 
 and had become mild ; in the other case it had acted as 
 a poison. 
 
 It is obvious, from what has been said, that lime from 
 the magnesian limestone may be applied in large quan- 
 tities to peats ; and that where lands have been injured 
 by the application of too large a quantity of magnesian 
 lime, peat will be a proper and efficient remedy. 
 
 I mentioned that magnesian limestones effervesced 
 little when plunged into an acid. A simple test of mag- 
 nesia in a limestone is this circumstance, and its render- 
 ing diluted nitric acid or aqua fortis milky. 
 
 From the analysis of Mr. Tennant, it appears that 
 the magnesian limestones contain from 
 
 20.3 to 22.5 magnesia. 
 ' 29.5 to 31.7 lime. 
 47.2 carbonic acid. 
 0.8 clay and oxide of iron. 
 
 Magnesian limestones are usually coloured brown or 
 pale yellow. They are found in Somersetshire, Lei- 
 cestershire, Derbyshire, Shropshire, Durham, and York- 
 shire. I have never met with any in other counties in 
 England ; but they abound in many parts of Ireland, 
 particularly near Belfast. 
 
 The use of lime as a cement, is not a proper subject 
 for extensive discussion in a course of Lectures on the 
 chemistry of agriculture ; yet as the theory of the opera- 
 tion of lime in this way is not fully stated in any elemen- 
 tary book that I have perused, I shall say a very few 
 w^ords on the applications of this part of chemical know- 
 ledge. 
 
 There are two modes in which lime acts as a cement ; 
 in its combination with water, and in its combination 
 with carbonic acid. 
 
 The hydrate of lime has been already mentioned. 
 When quicklime is rapidly made into a paste with wa- 
 ter, it soon loses its softness, and the water and the lime 
 
222 
 
 form togcllier a solid colicieiit mass, winch consists, us 
 has been staled before, of 17 parts of water to 55 
 parts of lime. When hydrate of lime whilst it is con- 
 solidating, is mixed with red oxide of iron, alumina, 
 or silica, tlie mixture becomes harder and more cohe- 
 rent than when lime alone is used : and it appears that 
 this is owing to a certain degree of chemical attraction 
 between hydrate of lime and these bodies ; and tfiey 
 render it less liable to decompose by the action of the 
 carbonic acid in the air, and less soluble in water. 
 
 The basis of all cements that are used for works 
 which are to be covered with water must be formed from 
 hydrate of lime ; and the lime made from impure lime- 
 stones answers this purpose very well. Puzzolana is 
 composed principally of silica, alumina, and oxide of 
 iron ; and it is used mixed with lime to form cements 
 intended to be employed under water. Mr. Smeaton, 
 in the construction of the Eddystone lighthouse, used a 
 cement composed of equal parts by weight of slacked 
 lime and puzzolana. Puzzolana is a decomposed lava. 
 Tarras, which was formerly imported in considerable 
 quantities from Holland, is a mere decomposed basalt : 
 two parts of slacked lime and one part of tarras forms 
 the principal part of the mortar used in the great dykes 
 of Holland. Substances which will answer all the 
 ends of puzzolana and tarras are abundant in the Bri- 
 tish islands. An excellent red tarras may be procured 
 in any quantities from the Giant's Causeway, in the 
 north of Ireland : and decomposing basalt is abundant 
 in many parts of Scotland, and in the northern districts 
 of England in which coal is found. 
 
 Parker's cement, and cements of the same kind made 
 at the alum works of Lord Dundas and Lord Mulgrave, 
 are mixtures of calcined ferruginous, siliceous, and alu^ 
 minous matter, with hydrate of lime. 
 
 The cements which act by combining with carbonic 
 acid, or the common mortars, are made by mixing to- 
 gether slacked lime and sand. These mortars, at first 
 solidify as hydrates, and are slowly converted into car- 
 bonate of lime by the action of the carbonic acid of the 
 air. Mr. Tennant found that a mortar of this kind in 
 4hree years and a quarter Iiad regained 63 per cent, of 
 
the quantity of carbonic acid gas which constitutes the 
 definite proportion in carbonate of lime. The rubbish 
 of mortar from houses owes its power to benefit lands 
 principally to the carbonate of lime it contains, and the 
 sand in it ; and its state of cohesion renders it particu- 
 larly fitted to improve clayey soils. 
 
 The hardness of the mortar in very old buildings de- 
 pends upon the perfect conversion of all its parts into 
 carbonate of lime. The purest limestones are tlie best 
 adapted for making this kind of mortar ; the magnesian 
 limestones make excellent water cements, but act with 
 too little energy upon carbonic acid gas to make good 
 common mortar. 
 
 The Romans according to Pliny, made their best 
 mortar a year before it was used : so that it was par- 
 tially combined with carbonic acid gas before it was 
 employed. 
 
 In burning lime there are some particular precautions 
 required for the different kinds of limestones. In ge- 
 neral, one bushel of coal is sufficient to make four or 
 five bushels of lime. The magnesian limestone re- 
 quires less fuel than the common limestone. In all 
 cases in which a limestone containing much aluminous 
 or siliceous earth is burnt, great care should be taken 
 to prevent the fire from becoming too intense ; for such 
 lime easily vitrifies, in consequence of the affinity of 
 lime for silica and alumina. And as in some places 
 there are no other limestones than such as contain other 
 eartlis, it is important to attend to this circumstance. 
 A moderately good lime may be made at a low red 
 heat ; but it will melt into a glass at a white heat. In 
 limekilns for burning such lime, there should be always 
 a damper. 
 
 In general, when limestones are not magnesian their 
 purity will be indicated by their loss of weight in burn- 
 ing ; the more they lose, the larger is the quantity of 
 calcareous matter they contain. The magnesian lime- 
 stones contain more carbonic acid than the common lime- 
 stones ; and I have found all of them lose more than 
 half their weight by calcination. 
 
 Besides being used in the forms of lime and carbon- 
 ?ite of lime, calcareous matter is applied for the pur- 
 poses of agriculture iu other combinations. One of thesis 
 
224 
 
 bodies is gyijsum or sulphate of lime. This substance 
 consists of sulphuric acid (the same body that exists 
 combined with water in oil of vitriol) and lime ; and 
 when dry it is composed of 55 parts of lime and 75 
 parts of sulphuric acid. Common gypsum or selenite, 
 such as that found at Shotover Hill, near Oxford, con- 
 tains, besides sulphuric acid and lime, a considerable 
 quantity of water ; and its composition may be thus ex- 
 pressed : 
 
 Sulphuric acid, one proportion - 75 
 Lime, one proportion - - 55 
 
 Water, two proportions - - 34 
 
 The nature of gypsum is easily demonstrated ; if oil 
 of vitriol be added to quicklime, there is a violent heat 
 produced ; when the mixture is ignited, water is given 
 off, and gypsum alone is the result, if the acid has been 
 used in sufficient quantity; and gypsum mixed with 
 quicklime, if the quantity has been deficient. Gypsum, 
 free from water, is sometimes found in nature, when it 
 is called anhydrous solenite. It is distinguished from 
 common gypsum by giving off no water when heated. 
 
 When gypsum, free from water, or deprived of wa- 
 ter by heat, is made into a paste with water, it rapidly 
 sets by combining with that fluid. Plaster of Paris is 
 powdered dry gypsum, and its property as a cement, 
 and in its use in making casts, depends upon its solidi- 
 fying a certain quantity of water, and making with it a 
 coherent mass. Gypsum is soluble in about 500 times 
 its weight of cold water, and is more soluble in hot wa- 
 ter ; so that when water has been boiled in contact with 
 gypsum, crystals of this substance are deposited as the 
 water cools. Gypsum is easily distinguished by its 
 properties of affording precipitates to solutions of oxa- 
 lates and of barytic salts. 
 
 Great difference of opinion has prevailed amongst 
 agriculturists with respect to the uses of gypsum. It 
 has been advantageously used in Kent, and various tes- 
 timonies in favour of its efficacy have been laid before 
 the Board of Agriculture of Mr. Smith. In America 
 it is imployed with signal success ; but in most coun- 
 ties of England it has failed, though tried in various 
 ways, and upon different crops. 
 
 Very discordant notions have been formed as to the 
 
225 
 
 mode of operation of gypsum. It has been supposed 
 by some persons to act by its power of attracting mois- 
 ture from the air ; but this agency must be compara- 
 tively insignificant. When combined with water, it re- 
 tains that fluid too powerfully to yield it to the roots 
 of the plant, and its adhesive attraction for moisture is 
 inconsiderable ; the small quantity in which it is used 
 likewise is a circumstance hostile to this idea. 
 
 It has been said that gypsum assists the putrefaction 
 of animal substances, and the decomposition of manure. 
 I have tried some experiments on this subject which are 
 contradictory to the notion. I mixed some minced veal 
 with about one-one hundredth part of its weight of gyp- 
 sum, and exposed some veal without gypsum under the 
 same circumstances ; there was no diff'erence in the time 
 in which they began to putrify, and the process seem- 
 ed to me most rapid in the case in which there was no 
 gypsum present. I made other similar mixtures, em- 
 ploying in some cases larger, and in some cases smaller 
 quantities of gypsum ; and I used pigeons' dung in one 
 instance instead of flesh, and with precisely similar re- 
 sults, it certainly in no case increased the rapidity of 
 putrefaction. 
 
 Though it is not generally known, yet a series of ex- 
 periments has been carried on for a great length of time 
 in this country upon the operation of gypsum as a ma- 
 nure. The Berkshire and the Wiltshire peat-ashes con- 
 tain a considerable portion of this substance. In the 
 Newbury peat-ashes I have found from one-fourth to 
 one-third of gypsum, and a larger quantity in some 
 peat-ashes from the neighbourhood of Stockbridge : the 
 other constituents of these ashes are calcareous, alumi- 
 nous, and siliceous earth, with variable quantities of 
 sulphate of potassa, a little common salt and sometimes 
 oxide of iron. The red ashes contain most of this last 
 substance. 
 
 These peat-ashes are used as a top dressing for cul- 
 tivated grasses, particularly sainfoin and clover. In ex- 
 amining the ashes of sainfoin, clover, and rye grass, I 
 found that they afforded considerable quantities of gyp- 
 sum ; and this substance, probably, is intimately com- 
 bined as a ncccssai-v part of their woody fibre. If this 
 
 F f 
 
326 
 
 l<b allowed, it is easy to explain tlie reason why it ope- 
 rates in such small quantities; for the whole of a clover 
 crop, or saiufoiu crop, on an acre, according to my es- 
 timation, would aiford hy incineration only three or four 
 Itusliels of gypsum. In examining the soil in a field 
 near Newbury, which w^as taken from below a foot-path 
 near the gate, where gypsum could not have been arti- 
 ficially furnished, I could not detect any of this substance 
 in it; and at the very time I collected the soil, the peat- 
 ashes were applied to the clover in the field. The rea- 
 son why gypsum is not generally efficacious, is probably 
 because most cultivated soils contain it in sufficient 
 quantities for the use of the grasses. In the common 
 course of cultivation gypsum is furnished in the manure ; 
 for it is contained in stable dung, and in the dung of all 
 cattle fed on grass ; and it is not taken up in corn crops, 
 or crops of peas and beans, and in very small quanti- 
 ties in turnip crops; but where lands are exclusive- 
 ly devoted to pasturage and hay, it will be continually 
 consumed. I have examined four different soils culti- 
 vated by a series of common courses of crops, for gyp- 
 sum. One was a light sand from Norfolk ; another a 
 •clay, bearing a good wheat, from Middlesex ; the third 
 a sand, from Sussex ; the fourth a clay, from Essex. I 
 found gypsum in all of them ; and in the Middlesex soil 
 it amounted nearly to one per cent. Lord Dundas in- 
 forms me, that having tried gypsum without any benefit 
 on two of his estates in Yorkshire, he was induced to 
 have the soil examined for gypsum, according to the 
 process described in the Fourth Lecture, and this sub- 
 stance was found in both the soils. 
 
 Should these statements be confirmed by future inqui- 
 ries, a practical inference of some value may be derived 
 from them. It is possible that lands which have ceased 
 to bear good crops of clover, or artificial grasses, may 
 be restored by being manured with gypsum. I have 
 mentioned that this substance is found in Oxfordshire ; 
 it is likewise abundant in many other parts of England; 
 in Gloucestershire, Somersetshire, Derbyshire, York- 
 shire, &c. and requires only pulverization for its prepa- 
 ration. 
 
 Some very interesting documents upon the use of sul- 
 
lihaie of ii'oii or green vilriol, wliich is a salt producid 
 from peat in Bedfordshire, have been laid belore tiie 
 Board by Dr. Pearson; and I have witnessed the fer- 
 tilizing effects of a fcrrnginous water used forirrijijatini;; 
 a grass meadow made by the Duke of Manchester at 
 Priestly Bog, near Woburn, an account of tiie produce 
 of which has been published by the Board of Agricul- 
 ture. 1 have no doubt that the peat salt and the vi- 
 triolic water acted chiefly l)y pro(hicing gypsum. 
 
 The soils on which both are eflicacious are calcare- 
 ous; and sulphate of iron is decomposed l)ythe carbon- 
 ate of lime in sucli soils. The sulpliatc of iron con- 
 sists of sulphuric acid and oxide of iron, and is an acid 
 and a very -soluble salt; when a solution of it is mixed 
 with carbonate of lime, the sulphuric acid quits tlje ox- 
 ide of iron to unite to the lime, and the compounds pro- 
 duced are insipid and comparatively insoluble. 
 
 I collected some of the decomposition from the ferrugi- 
 nous water on the soil in Priestley meadow. I found 
 it consisted of gypsum, carbonate of iron, and insoluble 
 sulphate of iron. The principal grasses in Priestley 
 meadow are, meadow fox-tail, cock's foot, meadow fes- 
 cue, fiorin, and sweet scented vernal grass. I have ex- 
 amined the ashes of three of these grasses, meadow fox- 
 tail, cock's foot, and fiorin. They contained a consi- 
 derable proportion of gypsum. 
 
 Vitriolic impregnations in soils where there is no cal- 
 careous matter, as in a soil from Lincolnshire, to which 
 I referred in the Fourth Lecture, are injurious; but it 
 is probably in consequence of their supplying an excess 
 of ferruginous matter to the sap. Oxide of iron in small 
 quantities forms a useful part of soils ; and, as is evi- 
 dent from the details in the Third Lecture, it is found 
 in the ashes of plants, and probably is hurtful only in 
 its acid combinations. 
 
 I have just mentioned certain peats, the ashes of which 
 afford gypsum; but it must not be inferred from this 
 that all peats agree with them. I have examined vari- 
 ous peat-ashes from Scotland, Ireland, Wales, and the 
 northern and western parts of England, ^vhich contain- 
 ed no quantity that could be useful: and these ashes 
 
,i2b 
 
 aboiuitled in silicious, aluminous earths, and oxide of 
 iron. 
 
 Lord Charleville found in some peat-ashes from Ire- 
 land sulphate of potassa, i. e. the sulphuric acid combi- 
 ned with potassa. 
 
 Vitriolic matter is usually formed in peats ; and if the 
 soil or substratum is calcareous, the ultimate result is 
 the production of ii;ypsum. In general, when a recent 
 peat-ash emits a strong smell resembling that of rotten 
 eggs when acted upon by vinegar, it will furnish gyp- 
 sum. 
 
 Phosphate of lime is a combination of phosphoric acid 
 and lime, one proportion of each. It is a compound in- 
 soluble in pure water, but soluble in water containing 
 any acid matter. It forms the greatest part of calcined 
 bones. It exists in most excrementitious substances, 
 and is found both in the straw and grain of wheat, bar- 
 ley, oats, and rye, and likewise in beans, peas and 
 tares. It exists in some places in these islands native, 
 but only in very small quantities. Phosphate of lime is 
 generally conveyed to the land in the composition of 
 other manure, and it is probably necessary to corn crops 
 and other white crops. 
 
 Bone ashes ground to powder will probably be found 
 useful on arable lands containing much vegetable mat- 
 ter, and may perhaps enable soft peats to produce 
 wheat ; but the powdered l)one in an uncalcined state 
 is much to be preferred in all cases when it can be pro- 
 cured. 
 
 The saline compounds of magnesia will require very 
 little discussion as to their uses as manures. The most 
 important relations of this subject to agriculture have 
 been considered in the former part of this Lecture, when 
 the application of the magnesian limestone was exam- 
 ined. In combination with sulphuric acid magnesia 
 forms a soluble salt, This substance, it is stated by 
 some inquirers, has been found of use as a manure ; but 
 it is not found in nature in sufficient af)undance, nor is 
 it capable of being made artiiicially sufficiently cheap to 
 be of useful application in the common course of hus- 
 bandry. 
 
229 
 
 Wood ashes consist principally of the vegetable alkali 
 united to carbonic acid ; and as this alkali is found in al- 
 most all plants, it is not difficult to conceive that it may 
 form an essential part of their organs. The general 
 tendency of the alkalies is to give solubility to vegetable 
 matters ; and in this way they may render carbonace- 
 ous and other substances capable of being taken up by 
 the tubes in the radical fibres of plants. The vegeta- 
 ble alkali likewise has a strong attraction for water, 
 and even in small quantities may tend to give a due de- 
 gree of moisture to the soil, or to other manures ; though 
 this operation from the small quantities used, or exist- 
 ing in the soil, can be only of a secondary kind. 
 
 The mineral alkali, or soda, is found in the ashes of 
 sea-weed, and may be procured by certain chemical 
 agencies from common salt. Common salt consists of 
 the metal named sodium, combined with chlorine ; and 
 pure soda consists of the same metal united to oxy- 
 gene. When water is present, which can afford oxy- 
 gene to the sodium, soda may be obtained in several 
 modes from salt. 
 
 The same reasoning will apply to the operation of 
 the pure mineral alkali, or the carbonated alkali, as to 
 that of the vegetable alkali ; and when common salts 
 acts as a manure, it is probably by entering into the 
 composition of the plant in the same manner as gypsum, 
 phosphate of lime, and the alkalies. Sir John Pringlc 
 has stated, that salt in small quantities assists the de- 
 composition of animal and vegetable matter. This cir- 
 cumstance may render it useful in certain soils. Com- 
 mon salt likewise is offensive to insects. — That in small 
 quantities it is sometimes a useful manure, 1 believe it 
 fully proved ; and it is probable that its efficacy depends 
 upon many combined causes. 
 
 Some persons have argued against the employment 
 of salt; because when used in large quantities, it either 
 does no good, or renders the ground sterile ; but this is 
 a very unfair mode of reasoning. That salt in large 
 quantities rendered lands barren, was known long be- 
 fore any records of agricultural science existed. We 
 read in the Scriptures, that Abimclech took the city of 
 Shechem, ^^ and ]>eat down the city and sowed it with 
 
2m 
 
 salt J*' that the soil might be for ever unliuitful. Vir- 
 gil reprobates a salt soil ; and Fliny, though he recom- , 
 mends giving salt to cattle, yet affirms, that when strew- 
 ed over land it renders it barren. But these are not ar- 
 guments against a proper application of it. Refuse salt 
 in Cornwall, which, however, likewise contains some 
 of the oil and exuviae of fish, has long been known as 
 an admirable manure. And the Chesliire farmers con- 
 tend for the benefit of tlie peculiar produce of their 
 country. 
 
 It is not unlikely, that the same causes influence the 
 eflects of salt, as those which act in modifying the ope- 
 ration of gypsum. Most lands in this island, particu- 
 larly those near the sea, probably contain a sufficient 
 quantity of salt for all the purposes of vegetation ; and 
 in such cases the supply of it to the soil will not only 
 be useless, but may be injurious. In great storms the 
 spray of the sea has been carried more than 50 miles 
 from the shore ; so that from this source salt must be 
 often supplied to the soil. 1 have found salt in all the 
 sandstone rocks that I have examined, and it must ex- 
 ist in the soil derived from these rocks. It is a constitu- 
 ent likewise of almost every kind of animal and vegeta- 
 ble manure. 
 
 Besides these compounds of the alkaline earths and 
 alkalies, many others have been recommended for the 
 purposes of increasing vegetation ; such are nitrPy or 
 the nitrous acid combined with potassa. Sir Kenelin 
 Digby states, that he made barley grow very luxuriantly 
 by watering it with a very weak solution of nitre ; but 
 he is to speculative a writer to awaken confidence in his 
 results. This substance consists of one proportion of 
 azote, six of oxygene, and one of potassium ; and it is 
 not unlikely that it may furnish azote to form albumen, 
 or gluten, in those plants that contain them ; but the 
 nitrous salts are too valuable for other purposes to be 
 used as manures. 
 
 Dr. Home states, that sidphate of potassa, which as 
 1 just now mentioned, is found in the ashes of some 
 peats, is a useful manure. But Mr. Naismith* ques- 
 
 * Elements of A^'iiculture, p. 78. 
 
2ai 
 
 tions his results ; and quotes experiments hostile to bis 
 opinion, and, as he conceives, unfavourable to the eflB- 
 cacy of any species of saline manure. 
 
 Much of the discordance of the evidence relating to 
 the eiTicacy of saline substances depends upon the cir- 
 cumstance of their having been used in different pro- 
 portions, and in general, in quantities much too large. 
 
 I made a number of experiments in May and June, 
 1807, on the effects of different saline substances on bar- 
 ley and on grass growing in the same garden, the soil 
 of which was a light sand, of which 100 parts were 
 composed of 60 parts of siliceous sand, and 24 parts 
 finely divided matter, consisting of seven parts carbon- 
 ate of lime, 12 parts alumina and silica, less than one 
 part saline matter, principally common salt, with a 
 trace of gypsum and sulphate of magnesia : the remain- 
 ing 16 parts were vegetable matter. 
 
 The solutions of the saline substances were used 
 twice a week, in the quantity of two ounces, on spots of 
 grass and corn, sufficiently remote from each other to 
 prevent any interference of results. The substances 
 tried were siqier-carhonate^ sulphate, acetate, nitrate^ 
 and muriate of potassa ; sulphate of soda, sulphate, 
 nitrate, muriate, and carbonate of ammonia. 1 found, 
 that in all cases when the quantity of the salt equalled 
 one-thirtieth part of the weight of the water, tlie effects 
 were injurious ; but least so in the instances of tlie car- 
 bonate, sulphate and muriate of ammonia. When the 
 quantities of the salts w^ere one-three hundredth part of 
 the solution the effects were different The plants wa- 
 tered with the solutions of the sulphates grew just in 
 the same manner as similar plants watered with rain 
 water. Those acted on by the solution of nitre, acetate, 
 and super-carbonate of potassa, and muriate of ammo- 
 nia, grew rather better. Those treated witli the solu- 
 tion of carbonate of ammonia grew most luxuriantly of 
 all. This last result is what might be expected," for 
 carbonate of ammonia consists of carbon, hydro^enc, 
 azote, and oxygene. There was, however, another re- 
 sult which I had not anticipated ; the plants watered 
 with solution of nitrate of ammonia did not grow better 
 than those watered with rain water. The solution red- 
 
2^2 
 
 dened litmus paper; and probably the free acid ex- 
 erted a prejudicial effect, and interfered with the re- 
 sult. 
 
 Soot doubtless owes part of its efficacy to the ammo- 
 niacal salt that it contains. The liquor produced by the 
 distillation of coal contains carbonate and acetate of am- 
 monia, and is said to be a very good manure. 
 
 In 1808, I found the growth of wheat in a field at 
 Koehampton assisted by a very weak solution of acetate 
 of ammonia. 
 
 Soapers' waste has been recommended as a manure, 
 and it has been supposed that its efficacy depended upon 
 the different saline matters it contains ; but their quan- 
 tity is very minute indeed, and its principal ingredients 
 are mild lime and quicklime. In the soapers' waste 
 from the best manufactories, there is scarcely a trace of 
 alkali. Lime moistened with sea water affords more 
 of this substance, and is said to have been used in some 
 cases with more benefit than common lime. 
 
 It is unnecessary to discuss to any greater extent the 
 effects of saline substances on vegetation ; except the 
 ammoniacal compounds, or the compounds containing 
 nitric, acetic, and carbonic acid ; none of them can af- 
 ford by their decomposition any of the common princi- 
 ples of vegetation, carbon, hydrogene, and oxygene. 
 
 The alkaline sulphates and the earthy muriates are 
 so seldom found in plants, or are found in such minute 
 quantities, that it can never be an object to aj)ply them 
 to the soil. It was stated in the beginning of this Lec- 
 ture, that the earthy and alkaline substances seem ne- 
 ver to be formed in vegetation ; and there is every rea- 
 son, likewise, to believe, that they are never decompo- 
 sed ; for after being absorbed they are found in their 
 ashes. 
 
 The metallic bases of them cannot exist in contact 
 •with aqueous fluids ; and these metallic 1)ases, like other 
 metals, have not as yet been resolved into any other 
 forms of matter by artificial processes ; they cortibinc 
 readily with other elements ; but they remain undes- 
 tructible, and can be traced undiminished in quantity^ 
 tlirouffh tlieir diversified combinations. 
 
LECTURE VIll. 
 
 On the Improvement of Lands by Burning ; chemical 
 Principles of this Operation. On Irrigation and its 
 Effects. On Fallowing ; its Disadvantages and 
 Uses. On the convertible Husbandry founded on re- 
 gular Rotations of different Crops. On Pasture ; 
 Views connected with its Application. On various 
 Agricultural Objects connected with Chemistry. Con- 
 clusion, 
 
 i HE improvement of sterile lauds by burning, was 
 known to the Romans. It is mentioned by Virgil in 
 the first book of the Georgics : " Sfepe etiam steriles 
 incendere profuit agros." It is a practice still much in use 
 in many parts of these Islands ; the theory of its opera- 
 tion has occasioned much discussion, both amongst sci- 
 entific men and farmers. It rests entirely itpon chemi- 
 cal doctrines ; and 1 trust I shall be able to ofier you 
 satisfactory elucidations on the subject. 
 
 The basis of all common soils as I stated in the Fourth 
 Lecture, are mixtures of the primitive earths and oxide 
 of iron ; and these earths have a certain degree of at- 
 traction for each other. To regard tliis attraction in its 
 proper point of view, it is only necessary to consider the 
 composition of any common siliceous stone. Feldspar, 
 for instance, contains sjliceons, aluminous, calcareous 
 earths, fixed alkali, and oxide of iron, which exist in 
 one com|)Oinid, in consequence of their chemical attrac- 
 tions for each other. Let this stone be ground into im- 
 palpable powder, it then becomes a substance like clay: 
 if the powder l)e heated very strongly it fuses, and on 
 cooling forms a coherent mass similar to the original 
 stone ; the parts separated by mechanical division ad- 
 here again in consequence of chemical attraction. If 
 the |)owder is heated less strongly the particles only su- 
 perficially combine with each other, and form a gritty 
 
234 
 
 mass, which, when broken into pieces, has the charac- 
 ters of sand. , 
 
 If the power of the powdered feldspar to absorb wa- 
 ter from tlie atmosphere before, and after the applica- 
 tion of the heat, be compared, it is found much less in 
 the last case. 
 
 The same eflect takes place when the powder of other 
 siliceous or aluminous stones is made the subject of ex- 
 periment. 
 
 I found that two equal portions of basalt ground into 
 impalpable powder, of which one had been strongly ig- 
 nited, and the other exposed only to a temperature equal 
 to that of boiling water, gained very difterent weights 
 in the same time when exposed to air. In four hours 
 the one had gained only two grains, whilst the other 
 had gained seven grains. 
 
 When clay or tenacious soils are burnt, the effect 
 is of the same kind ; they are brought nearer to a state 
 analogous to that of sands. 
 
 In the manufacture of bricks the general principle is 
 well illustrated ; if a piece of dry brick earth be appli- 
 ed to the tongue it will adhere to it very strongly, in 
 consequence of its power to absorb water ; but after it 
 has been burnt there will be scarcely a sensible adhe- 
 sion. 
 
 The process of burning renders the soil less com- 
 pact, less tenacious and retentive of moisture ; and 
 when properly applied, may convert a matter that was 
 stiff, damp, and in consequence cold, into one pow- 
 dery, dry, and warm ; and much more proper as a bed 
 for vegetable life. 
 
 The great objection made by speculative chemists to 
 paring and burning, is, that it destroys vegetable and 
 animal matter, or the manure in the soil ; but in cases 
 in which the texture of its earthy ingredients is perma- 
 nently improved, there is more than a compensation for 
 this temporary disadvantage. And in some soils where 
 there is an excess of inert vegetable matter, the de- 
 struction of it must be beneficial ; and the carbonace- 
 ous matter remaining in the ashes may be more useful 
 to the crop than the vegetable fibre, from which it was 
 prod u fed. 
 
235 
 
 I have exauiiiied by a chemical analysis three spe- 
 cimens of ashes from dillerent lands that had under- 
 gone paring and burning. The first was a quantity sent 
 to the Board by M. Boys of liellhanger, in Kent, 
 .whose treatise on paring and burning has been pub- 
 lished. They were from a chalk soil, and 200 grains 
 contained 
 
 80 Carbonate of lime. 
 11 Grypsum. 
 ! 9 Charcoal 
 
 15 Oxide of iron. 
 3 Saline matter. 
 Sulphate of potash. 
 
 Muriate of magnesia, with a minute quan- 
 tity of vegetable alkali. 
 The remainder alumina and silica. 
 
 Mr. Boys estimates that 2660 bushels are the com- 
 mon produce of an acre of ground, which, according 
 to his calculation would give 172900 lbs. containing 
 
 Carbonate of lime 
 
 69160 lbs. 
 
 Gypsum 
 
 9509.5 
 
 Oxide of iron 
 
 12967.5 
 
 Saline matter 
 
 2593.5 
 
 Charcoal - 
 
 7780.5 
 
 In this instance there was undoubtedly a very consi- 
 derable quantity of matter capable of being active as 
 manure produced in the operation of burning. The 
 charcoal was very finely divided ; and exposed on a 
 large surface on the field, must have been gradually 
 converted into carbonic acid. And gypsum and oxide 
 of iron, as I mentioned in the last Lecture, seem to 
 produce the very best effects when applied to lands con- 
 taining an excess of carbonate of lime. 
 
 The second specimen was from a soil near Coleor- 
 ton, in Leicestershire, containing only four per cent, of 
 carbonate of lime, and consisting of three-fourths light 
 siliceous sand, and about one-fourth clay. This had 
 
> 
 been iuii:' bcfurc burning, and 100 parts uf the ashes 
 
 gave. 
 
 6 parts charcoal 
 
 3 Muriate- of soda and sulphate of potash, 
 
 Avitli a trace of vegetable alkali. 
 9 Oxide of iron. 
 And the remainder the earths. 
 
 In this instance, as in the otlier, iinely divided char- 
 coal was found ; the solubility of wliich would be in- 
 creased by the presence of the alkali. 
 
 The tiiird instance was, that of a stiif clay, from 
 Mount's Kay, Cornwall. This land had been brought 
 into cultivation from a lieath by burning about ten years 
 before ; but having been neglected, furze was spring- 
 ing up in diifercnt parts of it, which gave rise to the se- 
 cond paring and burning. 100 parts of the ashes con- 
 tained 
 
 8 parts of charcoal. 
 
 2 of saline matter principally common s^t, 
 witli a little vegetable alkali. 
 
 7 Oxide of iron. 
 
 2 Carbonate of lime. 
 Remainder alumina and silica. 
 
 Here the quantity of charcoal was greater than in 
 the other instances. The salt, I suspect, was owing to 
 the vicinity of the sea, it being but two miles off. In 
 this land there was certainly an excess of dead vegeta- 
 ble fibre, as well as an i\nprofitable living vegetable 
 matter ; and I have since heard that a great improve- 
 ment took place. 
 
 Many obscure causes have been referred to for the 
 purpose of explaining the effects of paring and burning; 
 but I believe they maybe referred entirely to the dimi- 
 nution of the coherence and tenacity of clays, and to the 
 destruction of inert, and useless vegetable matter, and 
 its conversion into a manure. 
 
 Dr. Darwin, in his Phytologia, has supposed, that 
 
clay during torrelaction, may absorb some nutritive prin- 
 ciples from the atmosphere that afterwards may be sup- 
 plied to plants; but the earths are pure metallic oxides, 
 saturated with oxygene; and the tendency of burning is 
 to expel any other volatile principles that they may con- 
 tain in coml)ination. If the oxide of iron in soils is not 
 saturated with oxygene, torrefaction tends to produce 
 its further union with this principle; and hence in burn- 
 ing, the colour of clays changes to red. Tl^e oxide of 
 iron containing its full [iroportion of oxygene has less 
 attraction for acids than the other oxide, and is conse- 
 quently less likely to be dissolved by any fluid acids in 
 the soil ; and it appears in this state to act in the same 
 manner as the earths. A very ingenious author, whom 
 I quoted at the end of the last Lecture, supposes that 
 the oxide of iron when combined with carbonic acid is 
 poisonous to plants ; and that one use of torrefaction is 
 to expel- the carbonic acid from it ; but the carbonate of 
 iron is not soluble in water, and is a very inert substance; 
 and I have raised a luxuriant crop of cresses in a soil 
 composed of one-fifth carbonate of iron, and four-fifths 
 carbonate of lime. Carbonate of iron abounds in some 
 of the most fertile soils in England, particularly the red 
 hop soil. And there is no theoretical ground for sup- 
 posing, that carbonic acid, which is an essential food of 
 plants, should in any of its combinations be poisonous 
 to. them ; and it is known that lime and magnesia are 
 both noxious to vegetation, unless combined with this 
 principle. 
 
 All soils that contain too much dead vegetable fibre, 
 and which consequently lose from one- third to one- half 
 of their weight by incineration, and all such as contain 
 their earthy constituents in an impalpable state of divi- 
 sion, i. e. the stiff clays and marles, are improved by 
 burning; but in coarse sands, or rich soils containing a 
 just mixture of the earths; and in all cases in which the 
 texture is already sufficiently loose, or the organizablc 
 matter sufficiently soluble, the process of torrefaction 
 cannot be useful. 
 
 All poor siliceous sands must be injured by it ; and 
 here practice is found to accord with theory. Mr. 
 Young, in his Essay on Manures, states, " that he found 
 
26S 
 
 burning injure sand ;" and the operation is never per- 
 formed by good agriculturists upon siliceous sandy 
 soils, after they have once been brought into cultiva- 
 tion. 
 
 An intelligent farmer in Mount's Bay told me, that 
 he had pared and burned a small field several years ago, 
 which he had not been able to bring again into good con- 
 dition. 1 examined the spot, the grass was very poor 
 and scanty, and the soil an arid siliceous sand. 
 
 Irrigation or watering land, is a practice, which at 
 first view appears the reverse of torrefaction ; and in ge- 
 neral, in nature the operation of water is to bring earthy 
 substances into an extreme state of division. But in the 
 artificial watering of meadows, the beneficial effects de- 
 pend upon many different causes, some chemical, some 
 mechanical. 
 
 Water is absolutely essential to vegetation ; and when 
 land has been covered with water in the winter, or in 
 the beginning of spring, the moisture that has penetra- 
 ted deep into the soil, and even the subsoil, becomes a 
 source of nourishment to the roots of the plant in the 
 summer, and prevents those bad effects that often hap- 
 pen in lands in their natural state, from a long continu- 
 ance of dry weather. 
 
 When the water used in irrigation has flowed over a 
 calcareous country, it is generally found impregnated 
 with carbonate of lime ; and in this state it tends, in 
 many instances, to ameliorate the soil. 
 
 Common river water also generally contains a certain 
 portion of organizable matter, which is much greater 
 after rains, than at other times ; and which exists in 
 the largest quantity when the stream rises in a cultiva- 
 ted country. 
 
 Even in cases when the water used for flooding is 
 pure and free from animal or vegetable substances, it 
 acts by causing the more equable diffusion of nutritive 
 matter existing in the land ; and in very cold seasons it 
 preserves the tender roots and leaves of the grass from 
 being affected by frost. 
 
 Water is of greater specific gravity at 42® Fahren- 
 heit, than at 32°, the freezing point ; and hence in a 
 meadow irrigated in winter, the water immediately in 
 
239 
 
 contact with the grass is rarely below 40^; a degree of 
 temperature not at all prejudicial to the living organs of 
 plants. 
 
 In 1804, in the month of March, I examined the tem- 
 perature in a water meadow near Hungerford, in Berk- 
 shire, by a very delicate thermometer. The tempera- 
 ture of the air at seven in the morning was 29*^. The 
 water w^as frozen above the grass. The temperature of 
 the soil below the water in which the roots of the grass 
 were fixed, was 43^. 
 
 In general those waters which breed the best fish are 
 the best fitted for watering meadows ; but most of the 
 benefits of irrigation may be derived from any kind of 
 water. It is, however, a general principle, that waters 
 containing ferruginous impregnations, though possess- 
 ed of fertilizing effects, when applied to a calcareous 
 soil, are injurious on soils that do not effervesce with 
 acids; and that calcareous waters which are known by 
 the earthy deposit they afford when boiled, are of most 
 use on siliceous soils, or other soils containing no re- 
 markable quantity of carbonate of lime. 
 
 The most important processes for improving land, are 
 those which have been already discussed, and that are 
 founded upon the circumstance of removing certain con- 
 stituents from the soil, or adding others or changing 
 their nature ; but there is an operation of very ancient 
 practice still much employed, in which the soil is expo- 
 sed to the air, and submitted to processes which are 
 purely mechanical, namely , fallowing. 
 
 The benefits arising from fallows have been much 
 over-rated. A summer fallow, or a clean fallow, may 
 be sometimes necessary in lands overgrown with weeds, 
 particularly if they are sands which cannot be pared 
 and burnt with advantage; but is certainly unprofitable 
 as part of a general system in husbandry. 
 
 It has been supposed by some writers, that certain 
 principles necessary to fertility are derived from the at- 
 mosphere, which are exhausted by a succession of crops, 
 and that these are again supplied during the repose of 
 the land, and the exposure of the pulverized soil to the 
 influence of the air ; but this in truth is not the case. 
 The earths commonly found in soils cannot be combined 
 
240 
 
 with move oxygeuc ; none of them unite to azote ; and 
 such of them as arc capable of attracting carbonic acid, 
 are always saturated with it in those soils on which the 
 practice of fallowing is adopted. The vague ancient 
 opinion of the use of nitre, and of nitrous salts in ve- 
 getation, seems to have been one of the principal spe- 
 culative reasons for the defence of summer fallows. 
 ^Nitrous salts are produced during the exposure of soils 
 containing vegetable and animal remains, and in greatest 
 abundance in hot weather ; but it is probably by the 
 combination of azote from these remains with oxygene 
 in the atmosphere that the acid is formed ; and at the 
 expense of an element, which otherwise would have 
 formed ammonia ; the compounds of which, as is evi- 
 dent from what was stated in the last Lecture, are much 
 more efficacious than the nitrous compounds in assisting 
 vegetation. 
 
 When weeds are buried in the soil, by their gradual 
 decomposition they furnish a certain quantity of soluble 
 matter ; but it may be doubted whether there is as 
 much useful manure in the land at the end of a clean 
 fallow, as at the time the vegetables clothing the sur- 
 face were first ploughed in. Carbonic acid gas is form- 
 ed during the whole time by the action of the vegeta- 
 ble matter upon the oxygene of tlie air, and the greater 
 part of it is lost to the soil in wliich it was formed, and 
 dissipated in the atmosphere. 
 
 The action of the sun upon the surface of the soil 
 tends to disengage the gaseous and the volatile fluid 
 matters that it contains ; and heat increases the rapidity 
 of fermentation : and in the summer fallow, nourish- 
 ment is rapidly produced, at a time when no vegetables' 
 are present capable of absorbing it. 
 
 Land, when it is not employed in preparing food for 
 animals, should be applied to the purpose of the pre- 
 paration of manure for plants ; and this is effected by 
 means of green crops, in consequence of the absorption 
 of carbonaceous matter in the carbonic acid of tl/e at- 
 mosphere. In a summer's fallow a period is always 
 lost in which vegetables may be raised, cither as food 
 for animals, or as nourishment for the next crop ; and 
 the texture of the soil is not so much improved by its 
 
241 
 
 exposure as in winter, when the expansive powers of 
 ice, tlie gradual dissolution of snows, and the alterna- 
 tions from wet to dry, tend to pulverize it, and to mix 
 its different parts together. 
 
 In the drill husbandry the land is preserved clean by 
 the extirpation of the weeds by hand, and by raising 
 the crops in rows, which renders the destruction of the 
 weeds much more easy. Manure is supplied either by 
 the green crops themselves, or from the dung of the cat- 
 tle fed upon them ; and the plants having large sys- 
 tems of leaves, are made to alternate with those bear- 
 ing grain. 
 
 It is a great advantage in the convertible system of 
 cultivation, that the whole of the manure is employed ; 
 and that those parts of it which are not fitted for one 
 crop, remain as nourishmeut for another. Thus, in Mr. 
 Coke's course of crops, the turnip is the first in the or- 
 der of succession ; and this crop is manured with recent 
 dung, which immediately affords sufficient soluble mat- 
 ter for its nourishment ; and the heat produced in fer- 
 mentation assists the germination of the seed and the 
 growth of the plant. After turnips, barley with grass 
 seeds is sown ; and the laud having been little exhaust- 
 ed by the turnip crop, affords the soluble parts of the 
 decomposing manure to the grain. The grasses, rye 
 grass, and clover remain, which derive a small part 
 only of their organized matter from the soil, and proba- 
 bly consume the gypsum in the manure which would be 
 useless to other crops : these plants likewise by their 
 large systems of leaves, absorb a considerable quantity 
 of nourishment from the atmosphere; and wlien plough- 
 ed in at the end of two years, the decay of their roots 
 and leaves affords manure for tlie wheat crop ; and at 
 this period of the course, the woody fibre of the farm- 
 yard manure which contains the phosphate of lime and 
 the other difficultly soluble parts, is broken down ; and 
 as soon as the most exhausting crop is taken, recent ma- 
 nure is again applied. 
 
 Mr. Gregg, iwliose very enlightened system of culti- 
 vation has been published by the Board of Agriculture, 
 and who has the merit of first adopting a plan similar 
 to Mr. Coke's upou strong clays, suffers tlie ground af- 
 
 M b 
 
242 
 
 ter barley to remain at rest for two years in grass ; sows^ 
 peas and beans on the leys; ploughs in the pea or bean 
 stubble for wheat ; and in some instances, follows his 
 wheat crops by a course of winter tares and winter bar- 
 ley, which is eat off in the spring, before the land is 
 sowed for turnips. 
 
 Peas and beans, in all instances, seem well adapted 
 to prepare the ground for wheat ; and in some rich 
 lands, as in the alluvial soil of the Parret, mentioned 
 in the Fourth Lecture, and at the foot of the South 
 Downs in Sussex, they are raised in alternate crops for 
 years together. Peas and beans contain, as appears 
 from the analysis in the Third Lecture, a small quan- 
 tity of a matter analogous to albumen ; but it seems that 
 the azote which forms a constituent part of this matter, 
 is derived from the atmosphere. The dry bean leaf, 
 when burnt, yields a smell approaching to that of de- 
 composing animal matter; and in its decay in the soil, 
 may furnish principles capable of becoming a part of 
 the gluten in wheat. 
 
 Though the general composition of plants is very an- 
 alogous, yet the specific difference in the products of 
 many of them, and the facts stated in the last Lecture, 
 prove that they must derive different materials from the 
 soil; and though the vegetables having the smallest 
 systems of leaves will proportionably most exhaust the 
 soil of common nutritive matter, yet particular vegeta- 
 bles when their produce is carried oft", will require pe- 
 culiar principles to be supplied to the land in which they 
 grow. Strawberries and potatoes at first produce lux- 
 uriantly in virgin mould, recently turned up from pas- 
 tufe ; but in a few years they degenerate, and require a 
 fresh soil ; and the organization of these plants is such, 
 as to be constantly producing the migration of their lay- 
 ers : thus the strawberry, by its long shoots, is constant- 
 ly endeavouring to occupy a new soil ; and the fibrous 
 radicles of the potato produce bulbs at a considerable 
 distance from the parent plant. Lands, in a course of 
 years, often cease to aflbrd good cultivated grasses; 
 they become (as it is popularly said) tired of them^ and 
 one of the probable reasons for this was stated in the 
 last Lecture. 
 
24:i 
 
 The most remarkable instance of the powers of ve- 
 getables to exhaust the soil of certain principles neces- 
 sary to their growth is found in certain funguses. Mush- 
 rooms are said never to rise in two successive seasons 
 on the same spot; and the production of tlie phsenome- 
 na called fairy rings has been ascribed by Dr. Wollas- 
 ton to the power of the peculiar fungus which forms it, 
 to exhaust tlie soil of the nutriment necessary for tlie 
 growth of the species. The consequence is, that the 
 ring annually extends ; for no seeds will grow where 
 their parents grew before them ; and the interior part of 
 the circle has been exhausted by preceding crops ; but 
 where the fungus has died, nourishment is supplied for 
 grass, which usually rises within the circle, coarse, and 
 of a dark green colour. 
 
 When cattle are fed upon land not benefited by their 
 manure, the eflPect is always an exhaustion of the soil ; 
 this is particularly the case where carrying horses are 
 kept on estates ; they consume the pasture during the 
 night, and drop the greatest part of tlieir manure in the 
 day during their labour in the daytime. 
 
 The exportation of grain from a country, unless some 
 articles capable of becoming manure are introduced in 
 compensation, must ultimately tend to exhaust the soil. 
 Some of the spots, now desart sands in northern x^fri- 
 ca, and Asia Minor, w^ere anciently fertile. Sicily was 
 the granary of Italy ; and the quantity of corn carried 
 off from it by the Romans, is probably a chief cause of 
 its present sterility. In this island, our commercial 
 system at present has the effect of affording substances, 
 which in their use and decomposition must enrich the 
 land. Corn, sugar, tallow, oil, skins, furs, Avine, silk, 
 cotton, ^c. are imported, and iish are supplied from 
 the sea. Amongst our numerous exports woollen, and 
 linen, and leather goods, are almost the only substances 
 which contain any nutritive materials derived from the 
 soil. 
 
 In all courses of crops it is necessary that every part 
 of the soil should be made as useful as possi!)le to the 
 different plants ; but the depth of the furrow in plough- 
 ing must depend upon the nature of the soil, and of the 
 
244 
 
 subsoil. Ill I'ich clayey soils the furrow can scarcely 
 be too deep ; and even in sands, unless the subsoil con- 
 tains some principles noxious to vegetables, the same 
 practice should be adopted. When the roots are deep, 
 they are less liable to be injured, either by excess of 
 rain, or drought ; the layers shoot forth their radicles 
 into every part of the soil ; and the space from which 
 the nourishment is derived is more considerable, than 
 "when the seed is superficially inserted in the soil. 
 
 There has been much diflference of opinion with re- 
 spect to permanent pasture ; but the advantages or dis- 
 advantages can only be reasoned upon according to the 
 circumstances of situation and climate. Under the cir- 
 cumstances of irrigation, lands are extremely produc- 
 tive, with comparatively little labour ; and in climates 
 where great quantities of rain falls, the natural irriga- 
 tion produces the same effects as artificial. When hay 
 is in great demand, as sometimes happens in the neigh- 
 bourhood of the metropolis, where manure can be easily 
 procured, the application of it to pasture is repaid for 
 by the increase of crop ; but top-dressing grass land 
 with animal or vegetable manure, cannot be recommend- 
 ed as a general system. Dr. Coventry very justly ob- 
 serves, that there is a greater waste of the manure in 
 this case, than when it is ploughed into the soil for seed 
 crops. The loss by exposure to the air, and the sun- 
 shine, offer reasons in addition to those that have been 
 already quoted in the Sixth Lecture, for the application 
 of manure even in this case, in a state of incipient, and 
 not completed fermentation. 
 
 Very little attention has been paid to the nature of 
 the grasses best adapted for permanent pasture. The 
 chief circumstance which gives value to a grass, is the 
 quantity of nutritive matter that the whole crop will af- 
 ford ; but the time and duration of its produce are like- 
 wise points of great importance ; and a grass that sup- 
 plies green nutriment throughout the whole of the year, 
 may be more valuable than a grass which yields its pro- 
 duce only in summer, though the whole quantity of food 
 supplied by it should be much less. 
 
 The grasses that propagate themselves by layers, the 
 
245 
 
 different species of Agrostis, supply pasture throughout 
 the year ; and, as it has been mentioned on a former 
 occasion, the concrete sap stored up in their joints, ren- 
 ders them a good food even in winter. I saw four square 
 yards of iiorin grass cut in the end of January, this year, 
 in a meadqw exclusively appropriated to the cultivation 
 of florin, by the Countess of Hardwicke, the soil of 
 which is a damp stiff clay. They afforded 28 pounds 
 of fodder ; of which 1000 parts afforded, 64 parts of 
 nutritive matter, consisting nearly of one-sixth of sugar, 
 and five- sixths of mucilage, with a little extractive mat- 
 ter. In another experiment, four square yards gave 27 
 pounds of grass. The quality of this grass is inferior 
 to that of the florin referred to in the Table, in the lat- 
 ter part of the Third Lecture, which was cultivated by 
 Sir Joseph Banks in Middlesex, in a much richer soil, 
 and cut in December. 
 
 The florin grass, to be in perfection, requires a moist 
 climate or a wet soil, and it grows luxuriantly in cold 
 clays unfltted for other grasses. In light sands, and in 
 dry situations, its produce is much inferior as to quan- 
 tity and quality. 
 
 The common grasses, properly so called, that afford 
 most nutritive matter in early spring, jwe the vernal mea- 
 dow grass, and meadow fox-tail grass ; but their pro- 
 duce at the time of flowering and ripening the seed are 
 inferior to that of a great number of other grasses ; their 
 latter- math, is, however, abundant. 
 
 Tall fescue grass stands highest, according to the ex- 
 periments of the Duke of Bedford, of any grass, proper- 
 ly so called, as to the quantity of nutritive matter afford- 
 ed by the whole crop when cut at the time of flowering ; 
 and meadow cat's-tail grass affords most food when cut 
 at the time the seed is ripe; the highest latter-math pro- 
 duce of the grasses examined in the Duke of Bedford's 
 experiments is from the sea meadow grass. 
 
 Nature has provided in all permanent pastures a mix- 
 ture of various grasses, the produce of which differs at 
 different seasons. Where pastures are to be made ar- 
 tificially, such a mixture ought to be imitated; and, per- 
 haps, pastures superior to the natural ones may be made 
 
•Mb 
 
 by selecting due proportions of those species of gi'asses 
 fitted for the soil, which afford respectively the greatest 
 quantities of spring, summer, latter-math, and winter 
 produce ; a reference to the details in the Appendix will 
 shew that such a plan of cultivation is very practica- 
 ble. 
 
 In all lands, whether arable or pasture, weeds of every 
 description should be rooted out before the seed is ripe ; 
 and if they are suffered to remain iu hedge rows, they 
 should be cut when in flower, or before, and made into 
 heaps for manure ; in this case they will furnish more 
 nutritive matter in their decomposition ; and their in- 
 crease by the dispersion of seeds will be prevented. 
 The farmer, who suffers weeds to remain till their ripe 
 seeds are shed, and scattered by the winds, is not only 
 hostile to his own interests, but is likewise an enemy to 
 the public : a few thistles neglected will soon stock a 
 farm ; and by the light down which is attached to their 
 seeds, they may be distributed over a whole country. 
 Nature has provided such ample resources for the con- 
 tinuance of even the meanest vegetable tribes, that it is 
 very difficult to ensure the destruction of such as are 
 hostile to the agriculturist, even with every precaution. 
 Seeds excluded from the air, will remain for years in- 
 active in the soil,* and yet germinate under favourable 
 circumstances ; and the different plants, the seeds of 
 which, like those of the thistle and dandelion, are fur- 
 nished with beards or wings, may be brought from an 
 immense distance. The fleabane of Canada has only 
 lately been found in Europe ; and Linnseus supposes 
 that it has been transported from America, by the very 
 light downy plumes with which the seed is provided. 
 
 * The appearance of seeds in places where their parent plants are not 
 found may be easily accutinted for from this circumstance and olher 
 circumstances. Many seeds are carried from island to island by cur- 
 rents in the sea, and are defended by their hard coats from the im- 
 mediate acdon of the water. West Indian seeds (of this description) 
 are often found on our coasts, and readily germinate : their lcu>g voy- 
 af;e having been barely sufficient to afford the cotyledon its due pro- 
 portion of moisture. Other seeds are carried indigested in the sto- 
 mach of birds, and supplied with food at the moment of their depo- 
 sition. The light seeds of the mosses and lichens probably float in 
 every part of the atmosphere, and abound on the surface of the sea. 
 
247 
 
 In feeding cattle with green food, there are many ad- 
 vantages in soiling, or supplying them with food, where 
 their manure is preserved, out of the field ; the plants 
 are less injured when cut, than when torn or jagged by 
 the teeth of the cattle, and no food is wasted by being 
 trodden down. They are likewise obliged to feed with- 
 out making selection ; and in consequence the whole 
 food is consumed : the attachment, or dislike to a par- 
 ticular kind of food exhibited by animals, offers no proof 
 of its nutritive powers. Cattle at first refuse linseed 
 cake, one of the most nutritive substances on which they 
 can be fed.* 
 
 * For the following observations on the selection of different kinds 
 of common food by sheep and cattle I am obliged to Mr. George 
 Sinclair. 
 
 " Lolium fierenne, rye grass. Sheep eat this grass when it is in 
 the early stage of its growth, in preference to most others ; but af- 
 ter the seed approaches towaijds perfection, they leave it for almost 
 any other kind. A field in the Park at Woburn was laid down in 
 two equal parts, one part with rye grass and white clover, and the 
 other part with cock's-foot and red clover : from the spring till mid- 
 summer the sheep kept almost constantly on the rye grass ; but after 
 that time they left it, and adhered with equal constancy to the cock's- 
 foot during the remainder of the season. 
 
 Dactylis glomerata^ cock's-foot. Oxen, horses, and sheep, eat this 
 grass readily. The oxen continue to eat the straws and flowers from 
 the time of flowering till the time of perfecting the seed ; this was 
 exemplified in a striking manner in the field before alluded to. The 
 oxen generally kept to the cock's-foot and red clover, and the sheep 
 to the rye-grass and white clover. In the experiments published in 
 the Aiiioeuitates Academicae, by the pupils of Linnaeus, it is asserted 
 that this grass is rejected by oxen ; the above fact, however, is in 
 contradiction of it. 
 
 Alofiecurus firatensis, meadow fox-tail. Sheep and horses seem 
 to have a greater relish for this grass than oxen. It delighls in a soil 
 of intermediate quality as to moisture or dryness, and is very produc- 
 tive. In the water-meadow at Priestley, it constitutes a considerable 
 part of the produce of that excellent meadow. It there keeps inva- 
 riably possession of the top of the ridges, extending generally about 
 six feet from each side of the watercourse ; the space below that, to 
 where the ridge ends, is stocked with cock's foot, rough stalked mea- 
 dow grass, Festuca /iratensis, Fcstuca duriuscuia^ ji[^rostis stolonijc- 
 ra Agrostis /talus tris, and sweet-scented vernal grass, with a small 
 admixture of some other kinds. 
 
 P/ileuDi firatense, meadow cat's-tail. This grass is eaten without 
 reserve, by oxen, sheep, and horses. Dr. Pulteney says, that it is dis- 
 liked by sheep ; but in pastures where it abounds, it does not appear 
 robe rcjijcted bv these animals; but etucn ia cotninon viih S;ucb 
 
248 
 
 When food artificially composed is to be given to 
 cattle, it should be brought as nearly as possible to the 
 state of natural food. Thus, when sugar is given to 
 
 others as are growing with it. Hares are remarkably fond of it. The 
 Phleum nodosum^ Fhleum alfiinum,, Foa fertilise and Poa comfiressa^ 
 were left untouched, although they were closely adjoining to it. It 
 seems to attain the greatest perfection in a deep rich loam. 
 
 jigrostis stolonifera, florin. In the Experiments detailed in the 
 Amoenitates Academicse, it is said, that h-irses, sheep, and oxen, eat 
 this grass readily. On the Duke of Bedford's farm at Maulden, flo- 
 rin hay was placed in the racks belore horses in small distinct quan- 
 tities ; alternately with common hay ; but no decided preference for 
 either was manifested by the horses in this trial. But that cows and 
 horses prefer it to hay, when in a green state, seems fully proved by 
 Dr. Richardson, in his several publications on Fiorin ; and of its pro- 
 ductive powers in England (which has been doubted by some,) there 
 are satisfactory proofs. Lady Hardwicke has given an account of a 
 trial of this grass, wherein twenty-three milch cows, and one young 
 horse, besides a number of pigs, were kept a fortnight on the pro- 
 duce of one acre. 
 
 Poa (rivialis, rough-stalked meadow. Oxen, horses, and sheep, 
 eat this grass with avidity. Hares also eat it ; but they give a de- 
 cided preference to the smooth-stalked meadow-grass, to which it is, 
 in many respects nearly allied. 
 
 Poa /iratensis, smooth-stalked meadow grass. Oxen and horses 
 are observed to eat this grass in common with others ; but sheep 
 rather prefer the hard fescue, and sheeps' fescue, which affect a si- 
 milar soil. This species exhausts the soil in a greater degree than 
 almost any other species of grass ; the roots being numerous, and 
 powerfully creeping, become in two or three years completely matted 
 together ; the produce diminishes as this takes place. It grows 
 common in some meadows, dry banks, and even on walls. 
 
 Cijnosurus cristatus^ crested dog's-tail grass. The South Down 
 sheep, and deer, appear to be remarkably fond of this grass: in 
 some parts of Woburn Park this grass forms the principal part of 
 the herbage on which these animals chiefly browse : while another 
 part of the Park, that contains the Jgrostis cafiilaris, Jgrostis, fiu- 
 miliSy Festuca ovina, Fentuca duriuscula, and F'estuca cambrica^ is 
 seldom touched by them ; but the Welch breed of sheep almost 
 constantly browse upon these, and neglect the Cynosurus cristatusy 
 Lolium perenne^ and Poa trivialis. 
 
 Agrostis vulgaris [cafiillariSf Linn.,) fine bent ; common bent. 
 This is a very common grass on all poor dry sandy soils. It is not 
 palatable to cattle, as they never eat it readily, if any other kinds be 
 within their reach. The Welch sheep, however, prefer it as I be- 
 fore observed ; and it is singular, that those sheep being bred in the 
 park, when some of the best grasses are equally within their reach, 
 should still prefer those grasses which natuially grow on the Welch 
 mountains ; it seems to argue that such a preference is the effect ot 
 some other cause, than that of habit. 
 
 Festuca ovina, sheeps' fescue. All kinds of cattle relish this 
 
249 
 
 them; some dry fibrous matter should be mixed with it, 
 such as chopped straw, or dry withered grass, in order 
 that the functions of tiie stomach and bowels may be 
 
 grass; but it appears from the trial that has been made with it on 
 clayey soils, that it continues but a short time in possesbion of such, 
 being soon overpowered by the most luxuriant kinds. On diy shal- 
 low soils that are incapable of producing the larpjer sorts, this should 
 form the principal crop, or rather the whole ; for it is seldom or 
 never, in its natural state, found intimately mixed with others; but 
 by itself. 
 
 Festuca duriuscula, hard fescue grass. This is certainly one of 
 the best of the dwarf sorts of grasses. It is grateful to all kinds of 
 cattle ; hares are very fond of it : they cropped it close to the roots, 
 and neglected the Fustuca ovina., and Fustuca rubra, which were 
 contiguous to it. It is present in most good meadows and j)astures. 
 
 Festuca firatensis, meadow fescue. Tiiis gruss is seldom absent 
 from rich meadows and pastures ; it is observed to be highly grate- 
 ful to oxen, sheep, and horses, particularly the former. It appears 
 to grow most luxuriantly when combined with the hard fescue, and 
 Foa trivialis. 
 
 jivena eliator, tall oat-grass. This is a very productive grass, fre- 
 quent in meadows and pastures, but is disliked by cattle, particularly 
 by horses ; this, perfectly, agrees with the small portion of nutritive 
 matter which it affords. It seems to thrive best on a strong tena- 
 cious clay. 
 
 Avena JIavescens, yellow oat-grass. This grass seems partial to 
 dry soils, and meadows, and appears to be eaten by sheep and oxen, 
 equally with the meadow barley, crested dog's tail and sweet-scented 
 vernal grasses, which naturally grow in company with it. It nearly 
 doubles the quanlity of its produce by the application of calcareous 
 manure. 
 
 Holcus lanatus^ meadow soft grass. This is a very common grass, 
 and grows on all soils, from the richest to the poorest. It affords an 
 abundance of seed, wiiich is light, and easily dispersed by the wind. 
 It appears to be generally disliked by all sorts of cattle. The pro- 
 duce is not so great as a view of it in fields would indicate ; but 
 being left almost entirely untouched by cattle, it appears as the most 
 productive part of the herbage. The hay which is made of it, from 
 the number of downy hairs which cover the surface of the leaves, 
 is soft and spongy, and disliked by cattle in general. 
 
 Anthoxanthum odoratum., sweet-scented vernal grass. Horses, 
 oxen, and sheep, eat this grass; though in pastures where it is com- 
 bined with the meadow fox-tail, and white clover, cock's-foot, rough- 
 stalked meadow, it is left untouched, from which it would seem un- 
 palatable to cattle. Mr. Grant, of Leighton, laid down one half a 
 field of a considerable extent with this grass, combined with white 
 clover. The other half of the field with foxtail and red clover. 
 The sheep would not touch the sweet-scented vernal, but kept con- 
 stantly upon the fox-tail. The writer of this, saw the field when the 
 grasses were in the highest state of perfection ; and hardly any tiring 
 
 I i 
 
250 
 
 performed in a natural manuer. The principle is the 
 same as that of the practice alluded to ia the Third 
 Lecture, of giving chopped straw with harley. 
 
 In washing sheep, the use of water containing car- 
 bonate of lime should be avoided ; for this substance de- 
 composes the yolk of the wool, which is an animal soap, 
 the natural defence of the wool ; and wool often washed 
 in calcareous water, becomes roagli and more brittle. 
 The finest wool, sucli as tliat of the Spanish and Saxou 
 sheep, is most abundant in yolk. M. Vauquelin has 
 analysed several different species of yolk, and has found 
 the principal part of all of them a soap, with a basis of 
 potassa, (i. e. a compound of oily matter and potassa,) 
 with a little oily matter in excess. He has found in 
 them, likewise, a notable quantity of acetate of potassa, 
 and minute quantities of carbonate of potassa and mu- 
 riate of potassa, and a peculiar odorous animal matter. 
 
 M. Vauquelin states, that he found some specimens 
 of wool lose as much as 45 per cent, in being deprived 
 of their yolk ; and the smallest loss in his experiments 
 was 35 per cent. 
 
 The yolk is most useful to the wool on the back of 
 the sheep in cold and wet seasons ; probably the appli- 
 cation of a little soap of potassa, with excess of grease 
 to the sheep brought from warmer climates in our win- 
 ter, that is increasing their yolk artificially, might be 
 useful in cases where tiie fineness of the wool is of great 
 importance. A mixture of this kind is more conforma- 
 ble to nature, than that ingeniously adopted by Mr. 
 Blakewell ; but at the time his labours commenced, the 
 chemical nature of the yolk was unknown. 
 
 could be more satisfactory. Equal quantities of the seeds of white 
 clover, were sown with each of the grasses; but from the dwarf na- 
 ture of the sweet-scented vernal grass, the clover mixed with it had 
 attained to greater luxuriance, than that mixed with the meadow 
 foxtail." 
 
251 
 
 I have now exhausted all the subjects of (li.scussiouj> 
 which my experience or information has been able to 
 supply on the connexion of chemistry with agriculture. 
 
 1 venture to hope, that some of the views brought 
 forward, may contribute to the improvement of the most 
 important and useful of the arts. 
 
 I trust that the inquiry will be pursued by others ; 
 and that in proportion as chemical philosophy advances 
 towards perfection, it will afford new aids to agriculture. 
 
 There are sufficient motives connected both with 
 pleasure and profit, to encourage ingenious men to pur- 
 sue this new path of investigation. Science cannot 
 long be despised by any persons as the mere specula- 
 tion of theorists ; but must soon be considered by all 
 ranks of men in its true point of view, as the refine- 
 ment of common sense, guided by experience, gradually 
 substituting sound and rational principles, for vague 
 popular prejudices. 
 
 The soil offers inexhaustible resources, which, when 
 properly appreciated and employed, must increase our 
 wealth, our population, and our physical strength. 
 
 We possess advantages in the use of machinery, and 
 the division of labour, belonging to no other nation. 
 And the same energy of character, the same extent of 
 resources which have always distinguished the people 
 of the British Islands, and made tliem excel in arms, 
 commerce, letters, and philosophy, apply with the hap- 
 piest effect to the improvement of the cultivation of the 
 earth. Nothing is impossible to labour, aided by in- 
 genuity. The true objects of the agriculturist are like- 
 wise, those of the patriot. Men value most what they 
 have gained with effort ; a just confidence in their own • 
 powers results from success ; they love their country 
 better, because they have seen it improved by their own 
 talents and industry ; and they indentify with their in- 
 terests, the existence of those institutions which have 
 afforded them security, independence, and the multiplied 
 f^njoyments of civilized life. 
 
APPENDIX. 
 
 VCCOUNT OF THE RESULTS 
 
 EXPERIMENTS ON THE PRODUCE AND NUTRITIVE Ql^LI- 
 TIES OF DIFFERENT GRASSES, 
 
 AND OTHER PLANTS, 
 
 ISED AS THE FOOD OF ANIMALS. 
 
 ISSTITtTTED BT 
 
 JOHN. DUKE OF BEDFORD. 
 
INTRODIIC rrioN 
 
 nr Tin: Kin toil 
 
 Of the 215 proper grasses which are capahle of being 
 cultivated in this climate two only have heen employed 
 to any extent for niakini; artificial |)astnres, rye grass 
 and cock's-foot grass; and their a[)j)lication for this pur- 
 pose seems to have heen rather the result of accident, 
 than of any proofs of their superiority over other grasses. 
 
 A knowledge of the comparative merits and value of 
 all the dillerent species and varieties of grasses ciiririot 
 fail to he of the highest importance in practical agricul- 
 ture. The hope of obtaining this knowledge was the 
 motive that in(lu('ed the Duke of Jiedford to institute 
 this series of experiments. 
 
 Spots of ground, each containing four square feet, in 
 the garden at Woburn Abbey, were enclosed by iioards 
 in such a manner that there was no lateral communica- 
 tion between the earth included by the boards, and that 
 of the garden. 'I'he soil was removed in these enclo- 
 sures, and new soils supplied ; or mixtiire of soils were 
 made in them, to furnish as far as possible to the diller- 
 ent grasses those soils which seem most favourable to 
 their growth; a few varieties being adopted for the pur- 
 pose of ascertaining the eil'ect of diilereut soils in the 
 same plant. 
 
 The grasses were either planted or sown, and their 
 produce cat and collected and dried, at the pro[)er sea- 
 sons, in summer an<l autumn, by Mr. Sinclair, his 
 Grace's gardener. For the purpose of determining as 
 far as possible the nutritive powers of the dilfei eiit spe- 
 cies, equal weights of the dry grasses or vegetable sub- 
 stances were acted upon by hot water till all their solu- 
 ble parts were dissolved ; the solution was then evapu 
 
256 
 
 rated to dryness by a gentle heat in a proper stove, and 
 the matter obtained carefully weighed. This part of 
 the process was likewise conducted witli much address 
 and intelligence by Mr. Sinclair, by whom all the fol- 
 lowing details and calculations are furnished. 
 
 The dry extracts supposed to contain the nutritive 
 matter of the grasses, were sent to me for chemical ex- 
 amination, lihe composition of some of them is stated 
 in the table, page 106; 1 shall offer a few chemical ob- 
 servations on others at the end of this Appendix. It 
 will be found from the general conclusions that the mode 
 of determining the nutritive power of the grasses, by the 
 quantity of matter they contain soluble in water, is suffi- 
 ciently accurate for all the purposes of agricultural in- 
 vestigation. 
 
BOOKS QUOTED IN THE FOLLOWING PAGES. 
 
 Curt. Lond. — Flora Lomlincnsis. By William Curtis, 2 vols. London ir98, fol. 
 FI. Dan, — Flora Danica, or Icones Plantarum sponte nascentium in Regnis 
 
 Daniac et Norvegix, editae a Ge. ^?ider. Hafnise 1761, f'ol. 
 Engl. Bot. — English Botany, by J. E Smith, M. D. ; the Figures by J. Sower- 
 
 by, London 1790, 8vo. 
 W. B. — Botanical arrangements By Dr. Withering. London 1801, 4 vol. 
 Huds. — Hudson! Flora Anglica, 1778, vol. ii. 
 Host. G. A. — Nic 'J lioniae Host Iconcs et Descriptiones Gramlnum Austria- 
 
 coruni, vol. i. — iii. ^'illdobollae, 18U1, fol. 
 Hort. Kew. — Hortus Kewcnsis. By \V. J. Aiton, vol. i. London 1810. 
 
 K k 
 
258 
 
 Betaik of experiments on Grasses. By George Sinclaib, Gardener to his Grace 
 the UiTKE of Bbdfokd, and Corresp07iding Member of the Horticultural Society 
 of Edinburgh. 
 
 1. Anthoxanth7im odoratum, Eng'l, Bot. 647. — Curt. Lond. Sweet-scented ver- 
 nal grass. Nat. of Brit. 
 
 At the time of flowering', the produce from the space of an acre equal to 
 ,000091827364 of a brown sandy loam with manure, is 
 
 oz. or lbs per acre 
 
 Graes 11 oz. 8 Jr.* The produce per acre - 125235 = 7827 2 
 
 80 rfr. of irrass weigh when dry 21^ dr 1 ggg^g q = 2103 8 
 The produce of the space, ditto 49.1-j-o 3 
 The weight lost by the produce of one acre in 
 
 diying 5723 10 
 
 64</r. of gras- afford of nutritive matter 1 f/r. > jg^g jg „ i22 4 12 
 
 The produce of the space, ditto - 2.3-^1^ 5 " '^ 
 
 At the time the seed is ripe the produce is Grass, 
 
 9 oz. The produce per acre - - - 
 
 80 dr. of grass weight when dry 24 dr ■> 
 
 The produce of the space ditto - ^TS j 
 
 The weight lost by the produce of one acre in drying 
 
 64 dr. of grass afford of nutritive matter 3.1 dr. > 
 
 The produce of the space, ditto - 7.H dr. ^ 
 
 The weight of nutritive matter which is lost by 
 
 taking the crop at the time the grass is in 
 
 flower, exceeding half its value - - 188 12 _ 4 
 
 The proportional value which the grass at the time of flowering bears to 
 that at the time the seed is ripe, is as 4 to 13. 
 
 The latter-math produce is 
 Grass, 10 oz. The produce per acre - - 108900 = 6806 4 
 64 dr. of grass afford nutritive matter, 2.1 dr. 3828 8 = 239 4 8 
 
 The proportional value which the grass of the latter-math bears to that, at 
 the time the seed is ripe, is nearly as 9 to 13. 
 
 The smallness of the produce of this grass renders it improper for the pAr- 
 pose of hay ; but its early growth, and the superior quantity of nutritive mat- 
 ter which the latter-math affords, compared with the quantity afforded by 
 the grass at the time of flowering, causes it to rank high as a pasture grass, 
 on such soils as are well fitted for its growth ; such are peat-bogs, and lands 
 that are deep and moist. 
 II. Hokvs odoratus. Host. G. A. Growing in wooils. Sweet-scented soft 
 
 grass Nat of Germany. Flo Ger. — H borealis. Growing in moist meadows. 
 
 At the time of flowering, the produce from a rich and sandy loam is 
 
 Grass, 14 oz. The produce per acre ... 
 80 dr. of grass weigh when dry - 20.2 dr. f 
 The produce of the space, ditto - 57.1 y > 
 The weight lost by the produce of one acre in drying 
 
 • The weight is avoirdupois ; lbs. pounds, or. ounces, dr. drachms. The 
 weights not named are, quarters of drachms, and fractions of drachms ; tlius 
 7.1 V mieaiis 7 drachms 1 qvrarter of a drachm and i of a quarter. 
 
 98010 = 6125 10 
 
 
 
 29403 = 1837 11 
 
 
 
 = 4287 15 
 
 
 
 4977 10 = 311 1 
 
 1 
 
 oz. 
 152460 
 
 or lbs. per acre. 
 = 95 J8 12 
 
 39067 14 
 
 = 2441 11 14 
 
 . 
 
 7087 2 
 
v., 
 
 10124 13 
 
 or (hs. per acre 
 =. 610 15 6 
 
 35600 = 
 152460 
 
 35732 13 
 
 = 27225 
 
 <= 9528 12 
 
 17696 4 
 
 = 2233 4 1.1 
 
 APPENDIX. >i59 
 
 ^4 Jr. of grass afford of nutritive matter 4.1 dr. 7 
 The produce of the space, ditto 14.3^ > 
 
 At the- time the seed is ripe the produce is 
 Grass, 40 oz. Ti>c j.rodiice per acre - - *. 
 :64idr ofgrusSj .. ngh when dry - 28 rfr. > 
 
 Tlie produce of the space, ditto - 224 dr. $ 
 The weightiest uytlie produce of one acre in drying 
 64 dr. of grass afford nutritive matter 5.1 dr. 1 
 The produce of the spuce, ditto - 52.2 dr. 3 
 The weight of nutritive matter wiiich is lost by 
 
 taking the crop at the time tlie grass is in flower, 
 
 being more than half of its value 1600 8 10 
 
 The proportional value which the grass at the time of flowering beai-s to 
 that at the time the seed is ripe is as 17 to 21. 
 
 The produce of la\ter-malh is Grass, 25 oz. The 
 
 produce per acre 272250 =. 17015 10 
 
 64</r. of grass afford of nutritive matter 4.1 (/r. 18079 1= 1129 15 I 
 
 The grass of tlie latter-math crop, and of the crop at the time of flowering, 
 taking the whole quantity, and their relative proportions of nutritive matter, 
 are in value nearly as 6 to lU ; the value of the grass at tlie time the seed is 
 ripe, e-xceeds that of tlie latter-math, in proportion as 21 to 17. 
 
 Though this is one ot the earliest of tlie flowering grasses, it is tender, and 
 the produce in the spring is inconsiderable. If however, the quantity of nu- 
 tritive matter which it affords, be compared with that of any of those species 
 which flower nearly at the same time, it will be found greatly superior. It 
 seijds forth but a small number of flower stalks, which are of a slender structure 
 compared to the size of the leaves. This will accoiiut in a great measure for 
 the equal quantities of nutritive matter afforded by tiie grass at the time of 
 flowering, and the latter-math. 
 
 III. Cynosurus cxrulous. Eng;! Rot. 1613. Host. G. A. 2. t. 98. 
 Blue more-grass. Nat. of Britain. Sesleria caerulea. 
 
 At the time the seed is ripe the produce from a light sandy soil is 
 
 oz. ir. lbs. per acrCi 
 
 Grass, 10 oz. The produce per acre - - 108900 = 6806 4 
 64 dr. of grass afford of nutritive matter 3.3 </r. 6380 13= 398 12 13 
 
 The produce of this grass is greater than its appearance would denote ; the 
 leaves seldom attain to more than four or five inches in length, and the flower 
 stalks seldom arise to moi'e. Its growth is not rapid after being cropped, nor 
 does it seem to withstand the effects of frost, which if it happen to be 
 severe and early in the spring, checks it so much as to prevent it from flower- 
 ing for that season ; otherwise the quantity of nutritive matter which the 
 grass affords (for the straws are very inconsiderable,) would rank it as a va- 
 luable grass for permanent pasture. 
 
 IV. Jilopecurus pratends: Curt. Lond. Alo. myosuroides, 
 Meadow fox-tail- grsas. Nat. of Britain. Eng. Bot. 848. 
 
 At the time of flowering, the produce from the cl^ey loam is 
 
 Grass, 30 oz. The produce per acre - - - 
 80 dr. of grass weigh when dry - 24 dr. "> 
 
 The produce of the space, ditto - 336 dr. 3 
 The weig'it lost by the produce of one acre in drying 
 64 dr. of grass afford of nutritive matter 1 2 dr. ) 
 The produce of the space ditto - 11.1 dr,^ 
 
 The produce from :i sandy loam is 
 Grass, 12 oz 8 dr. The produce per aore 
 80 dr of grass weigh when dry 24 dr.") 
 
 The produce of tlie space, ditto 60 dr. ^ 
 
 60 dr. of grass afford of nutritive matter 1 dr. 5 
 The produce of the space, ditto 3.0i 5 
 
 oz. 
 326700 
 
 or lbs. per acre 
 = 20418 12 
 
 93010 
 
 = 1256 61 
 
 
 
 
 14293 2 
 
 
 
 7657 
 
 = 478 9 
 
 
 
 136125 
 
 = 8517 13 
 
 
 
 40837 
 
 9 - 2552 5 
 
 8 
 
 2126 
 
 15 ^ 132 H 
 
 1-5 
 
12931 
 
 u 
 
 
 
 5819 
 
 5 
 
 2 
 
 7111 
 
 8 14 
 
 461 
 
 
 
 4 
 
 26© AFl»liN131X. 
 
 At the time the seed is ripe, the produce from the clayey loam is 
 
 ox. or lbs. per acre 
 
 Grass, 19 ox. The produce per acre - - 2G6910 
 
 80 dr. of grass wcigli wlien dry 36 dr. \ o-^.^n 
 
 The produce of tlie space, ditto 136 3;^ 3 y-3l\J9 8 
 
 The welglu lost by the produce of one acre in drying 
 
 64. f/)\ of g-russ afford of nutritive matter 2.1 <//•.> ».^_^ . 
 
 The produce of the space, ditto 9.975 $ 
 
 The weiglit of nutritive matter which is lost by 
 
 leaving the crop till the seed be ripe, being 
 
 one twenty-fifth part of its value - If 8 11 
 
 The proportional value whicli the grass, at the time of flowering, bears to 
 that at the time the seed is ripe, is as 6 to 9. 
 
 The latter-math profluce, from the clay loam is 
 Grass, 12 02. '['he produce per acre - - 130680 = 8167 8 
 
 64 </)•. of grass afford of nutaitive matter 2dr.\ ,^„„ ,^ ^ 
 
 The produce of the space, ditto 6 dr. $ ^"""^ ^^ = -^^^ ^ ^^ 
 
 The proportional value which tlie wliole of the latter-math crop bears to that 
 
 at the time the seed is ripe, is as 5 to 9, and to that at the time of flowering, 
 
 proportionably as 13 to 24. 
 
 The above statement clearly shews that tliere is nearly three-fourths of pro- 
 duce greater from a clayey loam than from a sandy soil, and the grass from 
 the latter is comparatively of less value, in proportion as 4 to 6. The straws 
 produced by the sandy soil are deficient in number, and in every respect less 
 than those from the clayey loam : which will account for the unequal quantities 
 of nutritive matter afforded by them ; but the proportional value in which 
 the grass of the latter-math exceeds that of the crop at the time of flowering, 
 is as 4 to 3 : a difference whicii appears extraordinary, when the quantity of 
 flower-stalks which are in the grass at tlie time of flowering is considered. In 
 the Anthoxanthum odoratum the proportional difference between the grass of 
 these crops is still greater, nearly as 4 to 9 ; in the poa pratensis they are 
 equal ; but in all the latter flowering grasses experimented upon, the flower- 
 ing straws of which resemble those of the Alopeciirus pratensis or Anthoxanthum 
 odoratum, the greater proportional value is always on the contrary found in 
 the grass of the flowering crop. Whatever the cause may be, it is evident 
 that the loss sustained by taking the crops of these grasses at the time of 
 flowering is considerable. 
 
 V. Alopecurns alfnnus. Engl. Bot. 1126. 
 Alpine fox-tail grass. Nat of Scotland. 
 
 At the time of flowering, the produce from a sandy loam with a small por- 
 tion of manure, is 
 
 oz. or lbs. per acre 
 
 Grass, 8 oz. The produce per acre - - 87120 -= 5445 5 
 
 60 dr. of grass weigh when dry 16 dr. -) „o„.,„ ^ _ - . ,„ „ 
 
 The produce of the space, ditto 34j-|5 ^^^^ 0-1452 
 
 The weight lost by the produce of one acre in drying 3993 5 
 
 64rfr. of grass afford of nutritive matter 1 dr.\ ,o^, . qk ^ a 
 
 The produce of the space, ditto 2 dr.^ ^^^^ * == »5 1 4 
 
 VI. Poa alpina. Engl. Bot. 1003. Flo. Dan. 107, 
 Alpine meadow grass, Nat. of Scotland. 
 
 At the time of flowering, the produce from a light sandy loam, is 
 
 OS. or lbs. per acre 
 
 Grass, 8 oz. The produce per acre 87120 = 5445 
 
 64 dr of grass afford of nutritive matter 1.2 dr. 2041 14 = 127 9 14 
 
 VII. Avena pubeseens. Engl. Bot. 1640. Host. G. A. 2, t. 50. 
 Downy oat grass. Nat. of Britain. 
 
APPENDIX. ^t)t 
 
 At the time of flowering, the produce from a rich sandy soil is 
 
 oz. lbs. per acre 
 
 Grass, 23 oz. The produce per acre - - 250470 = 15654 6 
 80 f/r.ofgrass weigh when dry - SO t/r. > =. s«70 6 A 
 
 The produce ofthe space, ditto - 138</r.5 ^^^-^ U = 5870 4 
 
 The weight lost by the produce of one acre in 
 
 ■ drying - - 9783 15 12 
 
 64 dr. of grass afford of nutritive matter 1.2 rf''- } ^ 
 
 The produce of the space, ditto - 8.2,^5 ^^^^ ^= ^^^ ^^ ^ 
 
 At the time the seed is ripe, the produce is 
 Grass, 10 oz. Tlie produce per acre - - 108900 = 6806 4 
 . 80 </r. of grass weigh when dry - 16 dr.~i o,,oa n i^c, a r, 
 
 Tlie produce ofthe space, ditlo - 32 dr. $ 21780 = lo61 4 
 
 The weight lost by the produce of one acre in 
 
 drying 5445 
 
 64 Jr. of grass afford of nutritive matter 2 dr.") 3403 2 = 212 11 
 Tlie produce of the space, ditto 5 dr. $ "^ 
 
 The weiglit of nutritive matter which is lost by leaving the crop 
 
 till the Si ed be ripe, being more than half of its value - 154 6 3 
 
 The proportional value which the grass, at the time of flowering, bears to that 
 at the time the seed is ripe, is as 6 to 8. 
 
 The produce of latter-math is 
 Grass, 10 oz. The produce per acre - - 108900 = 6806 4 
 64 </»•. of grass afford of nutritive matter 2 dr. 3403 2 = 212 11 
 
 The proportional value which the grass, at the time of flowering, bears to 
 that of the latter-math, is as 6 to 8. The grass of tlie seed-crop, and that of 
 the latter-math, are of equal value. 
 
 The downy hairs which cover the surface of the leaves of this grass, when 
 growing on poor light soils, almost entirely disappear when it is cultiva- 
 ted on a richer soil. It possesses several good qualities which recommend it 
 to particidar notice ; it is hardy, early, and more productive than many otliers 
 which affect similar soils and situations. Its growth, after being cropped, is 
 tolerably rapid, although it does not attain to a great length if left growing ; 
 like the Poa pratensis, it sends forth flower stalks but once in a season, and it 
 appears well calculated for permanent pasture on rich light soils. 
 
 Vni. Poa pratensis. Curt. I^nd. Engl. Bot. 1073. 
 
 Smooth stalked meadow grass. Nat. of Britain. 
 
 At the time of flov/ering, the produce from a mixture of bog-earth and 
 clay, is 
 
 oz. or lbs. per acre 
 
 Grass, 15 oz. The produce per acre - - 163350 = 10209 6 
 80 </r. of grass weigh when dry - 22.2 dr.\ ..g 
 
 The produce of the space, ditto - 67.2 dr. ^ ^ ' ° -^ 
 The weight lost by the produce of one acre in 
 
 drying 7337 15 13 
 
 64 f/r. of grass afford of nutritive matter 1.3 t/r. 7 ^Acc n o^n ^ 
 
 The produce of the space, ditto - 6 2. J 5 '^'^'°° 9 = 279 2 9 
 
 At the time the seed is ripe the produce is 
 
 Grass, 12.8 oz. The produce per acre - 136825 
 
 80 dr. of gcass weigli when dry - 32 dr. 7 ,. , . _ 
 The produce of the space, ditto - 80 dr. $ * 
 
 The weight lost by tlie produce of one acre in drying 
 64 dr. of grass afford of nutri'Tve matter 1.2 <ir. ) 
 The produce of the space, ditto - 4.2 j\ S 
 The weight of nutritive matter which is lost by leaving the croo 
 till the seed be ripe, being nearly one fourth of its value - ' 79 12 
 
 == 8507 13 
 
 
 
 = 3403 2 
 
 
 
 5104 11 
 
 
 
 6 = 199 6 
 
 
 
262 APl'BNDIX. 
 
 The produce of latter-math is 
 
 oz. or Iba per acre 
 
 Grass, 6 oz. The produce per acre 653-10 ™ 4U83 12 
 
 64 »/r. of grass aHonl of outritiNc matter 1.3 </r. 1786 10 11110 
 
 Thr proportioiKil vahie iii which the prass of the latter-math exceeds tliat 
 of the flowering' crop, is as 6 to 7. I'lie grass of the seed crop and that of 
 the latter matli are of eipiai value 
 
 This jjniss is therefore of least vahic at the time the seed is npc ; a loss of 
 more than one-fourth of the value of the wliole crop is susiainetl if it is not 
 cut till that period : the straws are then dry, and tlie root leaves in a ickly 
 decaying state ; those of the unler-inath, on tlie contrary, are luxuriant and 
 healthy. This species sends Ibrth flower-staiks but once in a season, and 
 these being the most valuabh part of tiie plant for ilie purpose of hay ; it 
 will, from tiiis circumstance, ahd the superior value of tlu- grass of the latter- 
 matli, compared to tliat of the seed crop, appear well adapted for permanent 
 pasture. 
 
 IX. Poa ccentlea. — \sLr. Poa pratensis. Engl. Bot. 1004. Poa subcxrulea. 
 
 Short blueish meadow grass. Nat. of Britain. H. Kew. 1 — 155. Poa 
 humilis. 
 
 At the time of flowering, the produce from a soil of the like nature as the 
 preceding, is 
 
 Grass, 11 oz. Tiie produce per acre 
 64 dr. of grass aiford of nutritive matter 2 dr. ') 
 The produce of the sjiace, ditto 5.2 dr. 5 
 
 80 dr. of grass weigh wiieii ilry 24 <''• ) 
 
 The protluce of the space, ditto 52.3 jg 5 
 
 The weight lost by the produce of one acre in 
 
 drying - - 5240 13 
 
 If the produce of this variety be compared with that of the preceding one, 
 it will be found less ; nor does it seem to possess any superior excellence. The 
 superior nutritive power does not make up for tlie deficiency of produce by 
 80 lbs. of nutritive matter per acre. 
 
 X. Frstuca hordifurinis. Poa hordiformis. H. Cant. 
 Barley -like fescue grass. Nat. of Hungary. 
 
 At the time of flowering, the produce from a sandy soil, with manure is 
 
 oz or lbs. per acre 
 
 Grass, 20 oz The produce per acre - - 217800 0—13612 8 
 
 80 rfr.ofgt-ass weigh when dry - 24dr.^ 65340 =. 4083 12 
 The produce ot tlie space, ditto - Vo dr. y 
 The weight lost by the produce of one acre in 
 
 drying . 9528 12 
 
 • 64 </r. of grass aflbrd of nutritive matter 2 1 rfr. ^ -^.^ ^ .-o q . 
 
 The produce of the space, ditto 11.1 </r. 5 = 4/0 1/0 
 
 This is rather an early grass, though later than any of the preceding' spe- 
 cies ; its foliage is very fine, resembling the P. ditriiisciild, to which it seems 
 nearly allied, dilfering only in the length of the awns, and the glaucous colour 
 of the whole plant The consiilerable produce it alVords, and the nutritive 
 powers it appears to possess, joined to its early growth, are qualities which 
 strongly recommend it to further trial. 
 
 XI. Poatrivialis. CUirt. Lond. Kngl B 't. 1072. Host. G. A. 2. t. 62. 
 Roughish meadow grass. Nat. of Britain. 
 
 11970 
 
 or lbs. per acre 
 ^ 7486 14 
 
 3743 
 
 7 = 233 15 
 
 35037 
 
 =. 2246 1 
 
APFENDIX. 
 
 2m 
 
 At the time of flowering, the produce from a liglit brown loam, with ma- 
 
 nure, IS 
 
 119790 
 35937 
 
 or Iba. per acre 
 - 7486 14 
 
 
 
 374-3 7 
 
 125235 
 
 56355 12 
 
 5381 3 
 
 2246 1 
 
 5240 13 
 233 15 
 
 7827 3 
 3522 3 
 
 4304 15 
 336 5 
 
 Grass, 1 1 oz. The produce per acre 
 80 dv. of grass weigh wlicn dry - 24 fir. ) 
 
 The produce of tlie fTpace, ditto - ^'^luS 
 
 The weight lost by the produce of one acre in 
 
 dryini^ 
 
 64 dr. of grass afTonl of nutritive matter 2 dr. } 
 Thr produce of llu* space, ditto - 5.2 dr. 5 
 
 At the time tiic seed is ripe the produce is 
 Grass, 11.8 oz. The produce per acre 
 80 dr. of grass weigh when dry - 36 dr- f 
 
 The prochice of tlie spac<', ditto - 82.3-ig^3 
 The weight h)3t by the produce of one acre in 
 
 drying ..._... 
 64 dr. of grass afford of niitritire matter S-S^i ^ 
 The produce of lh(^ space, ditto - 7.3j 5 
 
 The weigiit of nutritive niatttr which is h)st by taking tiie crop at 
 
 the time of flowering, exceeihiig me fourth of its vaKie - 102 5 
 
 The proportional value in which the grass of the seed crop exceeds that at 
 the time of flowering is as 8 to 11. 
 
 The produce of latter math is 
 Grass, 7 oz. The pr-.duce per acre - - 76230 == 4764 6 
 
 64 dr of grass afliird of nutritive matter 3 dr. 3573 4 ■= 223 5 4 
 
 The proportional value by which the grass of the latter-math exceeds that 
 of thi flowering crop is as 8 to 12, and that of the seed crop as 11 to 12. 
 
 Mere then is a satisfactory proof of the superior value of the crop at the 
 time the seed is ripe, and of the consequent loss sustained by taking it when 
 in flow* r ; tiie produce of each crop being nearly ecpial. The deficiency of 
 hay in the flowering crop, in proportion to that of tl»e seed crop, is very stri- 
 king Its superior produce, the highly nutritive powers which the grass seems 
 to possess, and the season in which it arrives at perfection, are merits which 
 distuiguish ii xs one of tlie most valuable of those grasses, which affect moist 
 rich sods, and slieltered situatious ; but on dry exposed situations it is altoge- 
 ther inconsiderable ; it yearly diminishes, and ultimately dies off, not unfre- 
 quently in the space of four or five years. 
 
 XII. 
 
 Festuca glavca. Curtis. 
 
 Glaucous fescue gra-.s. Nat. of Britain 
 
 152460 
 60984 
 
 or Ibn. per acre 
 =. 9528 12 
 
 == 3811 8 
 
 5.1 rf)-. 5 
 
 32 *•> 
 89.2| 5 
 
 2573 4 
 
 Grass, 14 oz. The produce per acre 
 80 dr. of grass w 'i^h when dry 32 dr. 
 The produce of t ' space, ditto 89.2t^.'3j 
 
 The weight lost by die produce of one acre in 
 
 drying 
 
 64 dr. of gra.ss afford of imtritive matter 1.2 dr. '} 
 
 The produce of the space, ditto 
 
 At the time of flowering the produce is 
 
 Grass, 14 oz. The produce per acre 
 
 80 dr. of grass weigh when dry 
 
 The produce of the space, ditto 
 
 The weight lost by the produce^JP' one acre in 
 
 drying 
 
 64 dr of grass afford of nutritive matter 3 dr. 
 The produce of the space, ditto - 10.2 dr 
 The weight of nutritive matter which is lost by leaving the crop 
 
 till the seed be ripe, being half of the value of the crop - 223 
 
 152460 
 60984 
 
 7146 9 - 
 
 5717 4 
 223 5 
 
 9528 12 
 4811 8 
 
 5717 4 
 446 10 
 
264 • APPENDIX. 
 
 The propoilionul value by which the grass, at the time of flowering exceed? 
 that at the time the seed is ripe, is as 6*0 12. ^ 
 
 The proportional difference in the value of the flowering and seed crops of 
 this grass is directly the reverse of that of the preceding species, and affords 
 another strong proof of the value of the straws in grass which is intended for 
 hay. The straws, at the time of flowering, are of a very succulent nature ; 
 but from that period till the seed be perfected, they gradually become dry and 
 wiry. Nor does the root leaves sensibly increase in number or in size, but a 
 total suspension of increase appears in every part of the plant, the roots and 
 seed vessels excepted. The straws of the Poa trixrialis are, on the contrary, 
 at the time of flowering, weak and tender ; but as they advance towards the 
 period of ripening the seed, they become firm and succulent ; after that peri- 
 od, however, they rapidly dry up and appear little better than a mere dead 
 substance. 
 
 XIII. Festuca glabra. Wither. B. 2. P. 154. 
 Smooth fescue grass. Nat. of Scotland. 
 
 At the time of flowering, the produce from a clayey loam with manure is 
 
 or. or lbs. per acre 
 
 Grass, 21 or. The produce per acre - 228690 0=14293 
 
 80 tfr of gi-ass weigh when diy ^2 *?»-. ^ „. y,g -^^ S7\7 4 
 
 The produce of the space, ditto 134.1i%,t5 ^^*'° v-=:}fu 4 u 
 
 The weight lost by the produce of one acre in 
 
 drying - - 8576 14 
 
 64 dr. of gi-ass afft)rd of nutritive matter 2 dr. 7 "-iaa t\ jlaf. in n 
 
 The produce of the space, ditto 10.2 dr. 5 ^ 140 U = 440 lu u 
 
 At the time the seed is ripe the produce is 
 Gnss. 14 oz The produce per acre - - 152460 <= 9521 12 
 80 rfr.ofgrass weigh when dry . 32 Jn^ g^gg q == 3811 8 
 The producp of the space, ditto 89.2y 3 
 
 The weight lost by the produce of one acre in 
 
 drying 5717 4 
 
 64 dr. of grass afford of nutritive matter 1 1 <^''' ^ ocr 1 1 •• t o<: in 
 The produce of the space, ditto - 4.1tV5 ^^' ' ^^ =" ^^^ 1 ii 
 The weight of nutritive matter which is lost by leaving the crop 
 
 till the seed be ripe, exceeding half of its value - - 260 9 
 
 The proportional value which the grass at the time the seed is ripe, bears 
 to that of the crop at the time of flowering, is as 5 to 8. 
 
 The produce of latter-math is 
 Grass, 9 oz. The produce per acre 
 6t dr. of gi'ass afford of nutritive matter 2 ^r '^ 
 The produce of the space, ditto - l.O^Jr. 3 
 
 The proportior.al value which the grass of the latter-math be«rs to that of 
 the crop at the time of flowering, is as 2 to 8, and to that of the crop, at 
 the time tlie seed is ripe, is as 2 to 5. 
 
 The general appearance of t!»is grass is very slinihrr to that of the Featma 
 duriiMcafa : it is however, specifically dift'erent, and inferior in many respects, 
 which will be manifest on comparing their sevcnil prodiico with each other . 
 but if it be compared with some others, now under (jenct-a! ctillivation, the re- 
 sult is much in its favour, the soil which it affects being duly attended to. The 
 Anthoxunthum odovatum being taken as an example, it. appears that 
 
 Ids. per acre 
 Festuca glabra, affords of nutritive matter 
 
 From the crop at the time of fioweriivg - - - 446. > ,^^ 
 
 oz. 
 
 
 or 
 
 lbs. per acre 
 
 98010 
 
 
 
 ^ 
 
 6125 
 
 10 
 
 
 
 765 
 
 U 
 
 = 
 
 47 
 
 1.3 
 
 
 
APPENDIX. 
 
 265 
 
 Anthoxanthum odoratum, 
 
 ?:^ 
 
 At the time of flowering, ditto - - - - - 122. 
 At the time the seed is ripe, ditto .... 31 
 
 The weight of nutritive matter, which is afforded by the produce 
 of one acre of the Festuca glabra exceeding tliat of the Anthox- 
 anthum odoratum, in proportion nearly as 6 to 9, 
 
 lbs. per acre 
 
 433. 
 
 199. 
 
 XIV. 
 
 EesUica rubra. Wither. B. 2. P. 153. 
 Purple fescue grass.Nat. of Britain. 
 
 At the time of flowering, the produce from alight sandy soil, is 
 
 oz. 
 163350 
 
 
 56923 12 
 
 or tbs. per acre 
 = 102U9 6 
 
 3557 11 
 
 3828 8 
 
 6651 U 
 239 4 
 
 174240 
 r8408 
 
 =10890 
 = 4900 
 
 
 8 
 
 5445 
 
 5989 
 
 340 
 
 8 
 
 Grass, 15 oz. The produce per acre 
 80 dr. of grass weigh when dry - 34 dr. ") 
 
 The produce of the space, ditto - 102 dr. ^ 
 The weight lost by the produce of one acre in 
 
 drying ....... 
 
 64 dr. of grass afford of luitritive matter 1.2 dr. \ 
 The produce of the space, ditto - 22^ dr. 
 
 At the time the seed is ripe the produce is 
 Grass, 16 or The produce per acre 
 80 dr. of grass vVeigh when dry - 36 dr. ^ ^ 
 
 The produce of the space, ditto 115 3 //,.. 3 
 
 The weight lost by the produce of one acre in 
 
 drying 
 
 64 dr. of grass afford of nutritive matter 2 dr. , 
 The produce of the space, ditto - 8 dr. '. 
 
 The weight of nutritive matter which is lost by taking the crop 
 
 when the grass is in flower, being nearly one-third part of its 
 
 value - 101 
 
 The proportional value which the grass, at the time of flowering, bears to 
 that at the time the seed is ripe, is as 6 to 8. 
 
 This species is smaller in every respect than the preceding. The leaves 
 are seldom more than from three to four inches in length ; it affects a soil si- 
 milar to that favourable to the growth of the Festuca ovina, for which it would 
 be a profitable substitute, as will clearly appear on a comparison of their pro- 
 duce with each other 
 
 The produce of latter-math is 
 Grass, 5 oz. The produce per acre - . 54450 = 3403 2 
 
 64 t/r. of grass afford of nutritive matter 1.2 dr. 1276 2= 79 12 
 
 The proportional value which the grass of the latter-math bears to that at 
 the time the seed is ripe is as 6 to 8, and is of equal value with the gi-ass at the 
 time of flowering. 
 
 XV. Festuca ovina. Engl.fBot. 585. Wither. B. 2. P. 152. 
 Sheep's fescue grass. Nat. of Britain. 
 
 8 
 
 At the time the seed is ripe the produce is 
 
 Grass, 8 oz. The produce per acre 
 64 dr. of grass afford of nutritive matter 
 The produce of the space, ditto 
 The produce of latter-math is 
 Grass, 5 oz. The produce per acre 
 64 dr. of grass afford of nutritive matter 
 
 1.2 Jr.? 
 3dr.S 
 
 1.1 dr. 
 
 87120 
 2031 14 
 
 or lbs. per acre 
 
 
 = 5445 
 = 127 
 
 9 
 
 54450 
 1063 
 
 = 3403 
 
 7 = 
 
 66 
 
 The dry weight of this species was not ascertained, because the smallness 
 of the produce renders it entirely unfit for hay. If the nutritive powers of this 
 species be compared with those of the preceding, the inferiority will appear 
 thus : 
 
 l1 
 
1.21 
 
 1.1 5 
 
 266 APPENDIX. 
 
 Festuca ovina, (as above) ufToi'ds of nutritive matter 
 Ditto ditto ditto 
 
 Festuca nibra ditto ditto ~ < "12 
 
 Ditto > ditto ditto 1.2 5 
 
 The coniijarative degree of nourishment which the grass of the Festuca ru- 
 bra affords, exceeds therefore that aflorded by the F. ovina, in proportion as 
 11 to 14. 
 
 ^ From the trial that is here detailed, it does not seem to po.ssess the nutri- 
 tive powers generally ascribed to it ; it has the advantage of a fine foliage, and 
 may, therefore, very probably be better adapted to the masticating organs of 
 sheep, than the larger gi-asses, whose nutritive powers are shewn to be great- 
 er : hence on situations where it naturally gi'ows, and as pasture for sheep, it 
 may be inferior to few others. It possesses natural characters very distinct 
 from F. rubra. 
 
 XVI. Briza media. Engl. Bot. 340. Host. G. A. 2. t. 29. 
 Common quacking-grass. Nat. of Britain. 
 
 At tlie time of flowering, the produce from a rich brown loam, is 
 
 oz. or lbs. per acre 
 Grass, 14 oz. The produce per acre - - 152460 = 9528 12 
 80 f/r. of grass weigh when dry - 26 rfr. ^ ..oeAo o nnac ti a 
 
 The produce ofthe space, ditto 72.2-^^^,-. 5 *^^*^ 8=3096 13 8 
 
 The weight lost by the produce of one acre in 
 
 drying - ". - - 6431 14 8 
 
 64 </r. of grass aflbrd of nutritive matter 2.3 t/c.^ .^.^ „ .„„ _ ^ 
 
 The produce of the space, ditto - 9.2^*^5 ^^^^ U = 4Uy 7 U 
 
 At the time the seed is ripe the produce is 
 Grass, 14 oz. The produce per acre - - 152460 = 9528 12 
 80 Jr.ofg.-ass weigh when dry - 28. /r. 7 53362 = 3335 1 
 
 The produce of the space, ditto - 78.1|. 3 
 
 The weight lost by the produce of one acre in 
 
 drying - 6183 11 
 
 64 </r. of grass afford of nutritive matter 3.1 dr.') "jfrn \ = 483 14 1 
 
 The produce of the space, ditto - 11.1^) 
 
 The weight of nutritive matter which is lost by taking the crop at 
 
 the time of Howering, being nearly one-fourth part of its value 109 1 
 
 The proportional value wliich the grass at the time of flowering, bears to 
 tliat at tlie time the seed is ripe, is as 11 to 13. 
 
 The latter math produce is 
 
 oz. or Ihs. per acre 
 
 Grass, 12 oz. The produce per acre - - 130680 = 8167 8 
 64 <//•. of grass afford of MU'ritivi- niiiltcr Idr. 4083 12== 255 3 12 
 
 The pro])ortional value in which the grass at the time of flowering, exceeds 
 that of the latter math, is as 8 to 11; and thelatter-math stands to that at 
 tlie time the seed is ripe in proportion as 8 to 13. 
 
 The merits of this grass seem to demand notice ; its nutritive powers are 
 considerable, and its produce large when cbmpai-ed with others which affect 
 a similar soil. 
 
 XVII. Bactulis glomerala. Engl. Bot. ?35. Fl. Dan. 743. 
 Round-headed cocks-foot grass. Nat. of Britain. Wither. B. 2. E. 149. 
 
 At the time of flowering, the j)roduce from a rich sandy loam is 
 
 oz. lbs. per acre 
 
 Grass, 41 ox. The produce per acre - - 446490 0=27905 10 
 
APPENDIX. 
 
 267 
 
 'r.S 
 
 189758 4 
 
 or lbs. per acre 
 =11859 14 4 
 
 17424 
 
 16045 11 
 = 1089 
 
 424710 
 212355 
 
 = 26544 6 
 
 
 
 = 13272 
 13272 
 
 23SJ26 5 = 1451 10 
 
 80 dr. of grass weigh when dry - 34 dr. 
 
 The produce of the space, ditto 278^^ dr, 
 
 The weight lost by the produce of one acre in 
 
 drying 
 
 64 dr. of grass afford of nutritive matter 2.2 dr. ') 
 The produce of the space, ditto - 25.2^' > 
 
 At the time the seed is ripe the produce is 
 Grass, 39 oz. The produce per aci"e 
 80 dr. of grass weigh when dry - 40 dr. ^ 
 
 The produce of the space, ditto - 312 dr. 3 
 
 The weight lost by the produce of one acre 
 64 dr. of grass afibrd of nutritiv e matter 3.2 dr. ') 
 The produce of the space, ditto - 34.0^ 3 
 The weight of nutritive matter which is gained by leaving the crop 
 
 till the seed be ripe, being more than one-third part of its value, is 362 10 5 
 
 The proportional value which the grass at the time of flowering, bears to 
 that at the time the seed is ripe, is as 5 to 7, nearly. 
 
 The produce of the latter-math is 
 Grass, 17 oz. 8 ./r. The produce per acre - 190575 0=11910 15 
 64 Jr. of grass afford of nutritive matter 1.2 dr. 4466 9 = 281 10 9 
 
 The proportional value which the grass of the latter-math bears to that at 
 the time of flowering, is as 6 to 10 ; and to that at the time the seed is ripe, 
 as 6 to 14. 64. dr. of the' straws at the time of flowering afford of nutritive 
 matter 1.2 dr. The leaves or latter-math, and the straws simply, are there- 
 fore of equal pnoportional value; a circumstance which will point out this 
 grass to be more valuable for permanent pasture than for hay. The above de- 
 tails prove, that a loss of nearly one-third of the value of the crop is sustained, 
 if it is left till the period when the seed is ripe, though the proportional value 
 of the grass at that time is greater, i. e. as 7 to 5. The produce does not in- 
 crease if the grass is left growing after the period of flowering, but uniformly 
 decreases ; and the loss of latter-math, which, (from the rapid growth of the 
 foliage after the grass is cropped) is very considerable. These circumstances 
 point out the necessity of keeping this grass closely cropped, either with the 
 scythe or cattle, to reap the full benefit of its great merits. 
 
 XVIII. Bromus tectonm. Host. G. A. 1, t. 15. 
 
 Nodding pannicled brome-grass. Nat. of Europe Litroduced 1776. 
 H. K. 1. 168. 
 
 At the time of flowering, the produce from a light sandy soil, is 
 
 or lbs. per acre 
 Grass, 11 oz. The produce per acre 
 80 dr. of grass weigh when dry • 42 dr- ^ 
 
 The produce of the space, ditto - 92.1^3 
 
 Tlie weight lost by the produce of one acre in 
 
 drying 
 
 oz. 
 119790 = 7486 14 
 
 62889 12 == 3930 9 12- 
 
 3556 4 4 
 
 64 dr. of grass afford of nutritive matter 
 The produce of the space, ditto 
 
 3 dr. I 
 .1 dr. 3 
 
 5615 2 
 
 350 15 2 
 
 This species being strictly annual, affords no latter-math, which renders it 
 comparatively of little value. ^ 
 
 ZIX. Festuca cambrica. Hudson. W B. 2. P. 155. Nat. of Britain 
 
 At the time of flowering, the produce from a light sandy soil, is 
 
 oz. or lbs. per acrfe 
 
 Grass, 10 05, The produce per acre - - 108900 ..--6806 4 
 
268 APPENDIX. 
 
 oz. or IBe. per acre 
 
 80 r/r. of grass weigh when dry - 34 .A-. ? ^^^^^ 8=2892 10 8 
 
 1 he produce ot the space, ditto - 68 dr. > .v 
 
 The weight lost by the produce of one acre in 
 
 dr\ing - 3913 9 8 
 
 64 dr. of grass afford of nutritive matter 2.1 dr. ') 'laoa a _ 239 4 8 
 Tlie produce of the space, ditto - 5.2^ 5 '" 
 
 This species is nearly allied to the Festuca ovina, from which it differs little, 
 except that it is larger in every respect. The produce, and the nutritive mat- 
 ter which it affords, will be found superior to those given by the F. ovi7ia, if 
 they are brought into comparison. 
 
 XX. Brovms dlandnis. Curt. Lond. Engl. Bot. 1006. Nat. of Britain. 
 
 At the time the grass is ripe flower, the produce from a rich brown loam, is 
 Grass, 30 os. The produce per acre - - 326700 =20418 12 
 80 r/r.ofgrass weigh when dry - 34 Jr.? 138347 8 = 8677 15 
 
 The produce or the space, ditto ^04 dr. 3 
 
 I'he weight lost by the produce of one acre in 
 
 drying - 11740 13 
 
 64 </r. of grass afford of nutritive matter 3 f/r. > iroiA \ oer 9 1 
 
 The produce of the space, ditto - 22.2 5 1 =» vo/- ~ 1 
 
 This species, like the preceding, is strictly annual ; the above is therefore 
 the produce for one year, which, if compared to that of the least productive 
 of the perennial grasses, will be found inferior, and it must consequently be rC" 
 garded as unworthy of culture. 
 
 XXI. Poa angmtifolia. With. 2. P. 142. 
 Narrow-leaved meadow grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a brown loam, is 
 
 oz. or lbs. per acre 
 
 Grass, 27 02. The produce per acre - - 294030 0=18376 14 
 80 f/r. of grass weigh when dry - "* '^'•- ? 104962 12 - 7810 2 12 
 
 The produce ofthc space, ditto - 183.2| 5 1-*^°^ ^^ - '»^" ^ ^^ 
 
 The weight lost by the produce of one acre in 
 
 drying 10566 11 4 
 
 64 dr. of grass afford of nutritive matter 5 dr. ') ooscfi 11 1 A.'in « 11 
 
 The produce ofthe space, ditto - 33.3 5 ^-^»»o ^^ = i*ju on 
 
 At the time the seed is ripe, the produce is 
 
 Grass, 14 oz. The produce per acre - - 152460 = 9528 12 
 
 80 Jr. of grass weigh when dry - 32 Jr. ? f-r^Qf.. r. oo„ „ -. 
 
 The produce of the space, ditto - 89.2^ 5 ^"^^* = 08U 8 
 The weight lost by the produce of one acre in 
 
 drying 5717 4 
 
 64 Jr. of grass afford of nutritive matter 5.1 Jr.? lotAC t ■rni fi t 
 
 The produce of the space, ditto - 18.1^ 5 ^"^^^^ / - 7ui o 7 
 
 The weight of nutritive matter wliich is lost by leaving the crop 
 
 tiU the seed be ripe, exceeding one-third part of its value - 649 4 
 
 In the early growth of the leaves of this species of Poa, there is a striking 
 proof that early flowering in grasses is not always connected with the most 
 abundant early produce of leaves. In this respect all the species which have 
 already come under examination, are greatly inferior to that now spoken of. 
 Before the middle of April the leaves attain to the length of more than twelve 
 inches, and are soft and succulent ; in May, howevei", when the flower-stalks 
 make their appearance, it is subject to the disease termed rust, which af- 
 fects the whole plant ; the consequence of which is manifest in the great defi- 
 ciency of produce in the crop at the time the seed is ripe, being one-half less 
 than at the time of the flowering of the grass. Though this disease begins in 
 
APPENDIX. 269 
 
 the straws, the leaves suftcr most from its effects, being al the time tlie seed 
 is ripe completely dried up : the straws, therefore, constitute the principiil 
 part of the crop for mowing, and they contain more nutritive matter in propor- 
 tion than the leaves. This grass is evidently most valuable for pernjancnt jias- 
 ture, for which, in consequence of its srpcrior, rapid, and early growtii, and 
 the disease beginning at the straws, nature seems to have designed it. The 
 , grasses which approach neaiest to this in respect of early produt:e of leaves, 
 are tlie Poa fcrtilis, Dac'.ijlis glomerata, PIdcum pralenac, Jilofiecunta pralemis, 
 Jlvena etiator, and Bromus littoreus, all grasses of a coarser kind. 
 
 XXII. Avi-iM eliator. Curtis 191. Engl. Bot. 813. — Holcus avenaceus. 
 Tall oat -grass. Nat. of Britain. 
 
 At the time tlie seed is ripe, the produce is 
 
 oz. or Ihs, per acre 
 
 Grass,, 24 or. The produce per acre - - ,261360 0=16335 
 8 i *•. of grass weigh when dry - 28rf,-.> 91475 14 _ 5717 <i 14 
 
 The produce of the space, ditto 134.13 5 'dll.lti it - oiu J 14 
 
 e weight lost by the produce of one acre in 
 
 '.niag , - . . . 10617 12 2 
 
 (ir. of grass afford of nutritive matter 1 dr.') >inpo «<> nee o 10 
 
 The produce of the space, ditto - 6 Jr. 5 *iJ»J l^ - ^55 6 IZ 
 
 The produce of latter-math is. 
 Grass, 20 oz. The produce per acre - - 217800 0=13612 8 
 64 dr of grass afford of nutritive matter 1.1 dr. 4ii53 14 = 265 13 14 
 
 The weight of nutritive matter which is afforded by the crop of 
 
 the latter-math, exceeding that afforded by the grass of the seed 
 
 crop in proportion nearly as 26 to 25. - - - - 10 9 2 
 
 This grass sends forth flower straws during the whole Season ; the latter- 
 math contains nearly an equal number with the flowering crop. It is subject 
 to the rust, but the disease does not make its appearance till after the period 
 of flowering; it affects the whole plant, and at the time the seed is npe the 
 leaves and straws are withered and dry. This accounts for tlie superior value 
 of the latter-math over the seed crop, and points out the propriety of taking 
 the crop when the grass is in flower. 
 
 XXIII. Poa eliator. Curtis, 50. 
 Tall-meadow grass. Nat, of Scotland. 
 
 At the time of flowering, the produce from a rich clayey loam, is 
 
 Grass, 18 02. The produce per acre 
 80 dr. of grass weigli when dry 28 dr. ") 
 
 Tlie produce of the space, ditto 100.3 .? ^ 
 
 64 dr. of grass afford of nutritive matter 3.2 dr. " 
 Tlie produce of the space, ditto - 15.3 
 
 The weight lost by the produce of one acre in 
 
 drying .... .... 36I7 15 3 
 
 The botanical characters of this g^ass are almost the same as those of thf^ 
 ^vena eliator, differing in the want of the awns only. It has the essential cha 
 racter of the Hold (Florets male, and hermaphrodite. Calyx husks two-valved 
 with two florets) and since the Aveiia eliator is now referred to that ^cw\^ Ibis 
 may with certainty be considered a variety of it. 
 
 XXIV. Fentuca duriusada. Engl. Bot. 470. W. B. 9. P. 153. 
 Hard fescue grass Nat. of Britain. 
 
 oz. 
 196020 
 
 or lbs. per acre 
 =-12251 4 
 
 60607 
 
 =- 4287 15 
 
 10719 
 
 13 = 669 15 13 
 
270 APPENDIX. 
 
 At the time of flowering, tlie produce from a light sandy loam, is 
 
 or. or Ids. per acre 
 
 Grass, 27.8 or. The produce per acre - 294030 0=18376 14 
 80 f/;-. of grass weigh when dry - 26 dr.-^ ,„„,,„ 
 
 The produce of the space, ditto 194 l| $ ^''^'^^^ 8 = 8259 9 
 The weight lost by the produce of one acre in 
 
 drying - . . 10106 4 8 
 
 <J4 ^/r. of grass afford of nutritive matter 3.2 Jr. ^ i/jnro io inri/i m: to 
 
 The produce of the space, ditto 23.2^ 5 ^°^7y ^^ = ^^^* ^^ ^"^ 
 
 At the time the seed is ripe the produce is 
 
 Grass, 23 o:. The produce per acre - - 304920 0=19075 8 
 
 80 if/r. of irrass weitih when dry - 36dr. 1 io-oi.< n o«^-r«: ia n 
 ,p. f £. ., *^ , y,: cm o2 c 1'37214 = 8j75 14 
 
 The produce ot the sjntcc, ditto «01..Jy3 
 
 The weight lost by tlie produce of one acre in 
 
 drying ... - 10481 10 
 
 64 Jr. of grass afford of nutritive matter 1.2 Jr.^ .y,^/- „ aac ^n n 
 
 The produce of the space, ditto 10.2 Jr. 5 /^^^ ^= ^"^^ ^^ ^ 
 
 The weight of nutritive matter which is lost by leaving the crop 
 
 till the seed be ripe, exceeding one-half of its value - 558 5 3 
 
 The proportion.ll value which tlie grass, at the time the seed is ripe, beai'S to 
 
 that at the time of flowering, is as 6 to 14, nearly. 
 
 The produce of latter-math is, 
 Grass, 15 or. The produce per acre - - 163350 =.10209 6 
 64 Jr. of grass afford of nutritive matter 1.1 Jr. 3190 4= 199 6 4 
 
 The proportional value wliich the grass of the latter-math bears to that at 
 the time of flowering, is as 5 to 14, and to that at the time the seed is ripe, 
 5 to 6. 
 
 The above particulars will confirm the favourable opinion which was given 
 of this grass when speaking of the Festuca hordifovmis, and F. glabra. Its pro- 
 duce in the spring is not very great, but of the finest quality, and at the tim« 
 of flowering is considerable. If it be compared with" those affecting similar 
 soils such as Foa pratensis, Festuca ovina, &,c. either considered as a grass for 
 hay, or permanent pasture, it will be found of greater \iJuc. 
 
 XXV. Bromns erectus. Engl. Bot. 471. Host. G. A. 
 Upright perennial brome glass. Nat. of Britain. 
 
 At the time of flowering, the produce from a rich sandy soil, is 
 
 oz or lbs. per acre 
 
 Crass, 19 or. The produce per acre - - 206910 0=1293114 
 «0 Jr. of grass weigh when dry - ^^ :';-l 93109 8 = 5819 5 8 
 
 the produce of tlie space, ditto - 136. oy > 
 The weight lost by the produce of one acre in 
 
 drying - " 7112 8 S 
 
 ji4 Jr. of grass .-ifl-ord of nutritive matter 2.3 Jr. ^ 8890 10= 555 10 10- 
 The produce of the spiice, ditto - lo.Oj > 
 
 XXVI. Milivm efusunu Curt. Lond. Engl. Bot. 1106. 
 Common millet grass. Nat. of Britain 
 
 At the time of flowering, the produce from a light sandy soil, is 
 
 oz, or llis. per acre 
 
 tJrass, 11 or. 8 Jr. The produce per acre - 196020 0=12251 4 
 
 80 Jr. of grass u-eigh when dry ^^Irf^J 7595712=4747 5 li 
 The produce of the space, ditto lll.Sg- y 
 
 64 dr. of grass allord of nutritive matter 1.3 Jr. ^ ^r, -q ,^ _ no^ , - j^ 
 
 The produce of the space, ditto 7.3* S ~ 
 
APPENDIX. 
 
 271 
 
 ' This species in its natural state seems confined to woods as its place of 
 ^jTowth ; but the trial that is here mentioned, confirms the opinion that it will 
 grow and tlirive in open exposed situations. It is remarkable for the light- 
 ness of the produce, in proportion to its bulk. It ])r()duces foliage early in tlie 
 spring- in considerable abundance ; but its nutritive powers appear compara- 
 tively little. 
 
 XXVII. Festnca pratensis. Engl. Bot. 1592. C.Long. 
 Meadow fescue grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a bog soil, with coal ashes for 
 taanure, is 
 
 or lbs. per acre 
 
 
 dr. ■) 
 
 dr-S 
 
 oz. 
 217800 
 
 
 
 103455 8 
 
 .13612 
 6465 15 
 
 15314 1 
 
 304920 
 121968 
 
 7146 
 = 957 
 
 =19057 
 -= 7623 
 
 7146 9 
 
 11434 8 
 446 10 
 
 Grass, 20 oz. The produce per acre 
 
 80 dr. of grass weigh when dry - 38 dr 
 
 The produce of the space, ditto - 152 
 
 The weight lost by the produce of one acre in 
 
 drying - - - ' - 
 
 64 dr. of grass afford of nutritive matter 4.2 dr. ') 
 The produce of the space, ditto 22.2 dr. > 
 
 At the time the seed is ripe the produce is 
 
 Grass, 28 oz The produce per acre 
 80 dr. of gi-ass weigh when dry 32 dr. ') 
 
 The produce of the space, ditto 179.0* 5 
 
 The weight lost by the produce of one acre in 
 
 drying ........ 
 
 64 dr. of grass afford of nutritive matter 1.2 dr. ~) 
 The produce of the space, ditto 10.2 dr. 5 
 
 The weight of nutritive matter which is lost by leaving the crop 
 
 till the seed be ripe, exceeding one-half of its value - 510 7 8 
 
 The value of the grass at the time the seed is ripe, is to that of the grass at 
 the time of flowering, as 6 to 18. . 
 
 The loss which is sustained by leaving the crop of this grass till the seed be 
 ripe, is very great. That it loses more of its weight in drying at this stage of 
 growth, than at the time of flowering, perfectly agrees with the deficiency of 
 nutritive matter in the seed crop, in proportion to that in the flowering crop : 
 the straws being succulent in the former, they constitute the greatest part of 
 the weight ; but in the latter they are compat atively withered and dry, conse- 
 quently the leaves constitute the greatest part of the weight. It may be ob- 
 served here, that there is a great difference between straws or leaves that 
 have been dried after they were cut m a succulent state, and those which arc 
 dried (if I may so express it) by nature whde growing. The former retain all 
 their nutritive powers ; but the latter, if completely dry, very little, if any. 
 
 XXVIII. Lolium perenne. Engl. Bot. 315. Flo. Dan. 747. 
 Perennial rye-grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a rich brown loam is 
 
 oz. or lbs. per acre 
 
 Grass, 11 o:. 8 (/n The produce per acre - 125235 = 7827 3 
 
 80 dr. of grass weigh when dry 
 The produce of the space, ditto 
 
 78 
 
 34 dr. ■ 
 
 4 
 
 53156 13 = 3322 4 li 
 
 The weight lost by the produce of one acre in 
 
 drying -.-.... 
 
 64 dr. of grass aflTord of nutritive matter 2.2 '/'•• V 
 The pro<iuce of the space, ditto - 7.0| $ 
 
 At the time the seed is ripe, the produce is 
 
 drass, 22 oz. The produce per acre 
 
 4891 15 
 
 4494 14 3 
 305 11 15 
 
 239580 =14973 12 
 
272 
 
 APPSNDIX. 
 
 I 5 
 
 or. or llis. pel" acre 
 
 71874 = +492 2 
 
 10294 
 
 10481 
 7 = 643 
 
 8 8 
 
 80 dr. of grass weigh when thy - 24 
 
 The proch'ce of the space, ditto 105.2| 
 
 I'ht weight lost by the produce of one acre in 
 
 drying - - 
 
 64 til- of grass afford of nutritive matter 2.3 "''• ; 
 The produce of the space, ditto - 15.0-iV; 
 
 The weight of nutritive matter which is lost by taking the crop 
 at the time of flowering, nearly one-half of its value - - S3T 
 The proportional value whicii the grass, at the time of flowciing, bears to 
 
 that at ilie time the seed is ripe, is as 10 to 11. 
 
 The [)roduce of latter-math is 
 
 Grass, 5 nz. The produce per acre - - 54450 =-= 3403 2 ' 
 
 64 </f. of gi-ass afford of nutritive matter 1 </>•. 850 12.== 53 2 12 
 
 The proportional value wiiich the grass of the lalter-matli bears to that at 
 the time of flowering, is as 4 to 10, and to that at the time the seed is ripe, as 
 4 to 11. 
 
 XXIX. Poa maritima. Engl. Rot. 1140. 
 
 Sea meadow grass. Nat. of Britain. 
 
 At tlie time of flowering, the produce fi-om a light brown loam, is 
 
 •Grass, 18 or. The produce per acre 
 80 dv. of grass weigh when dry 
 The produce of the space, ditto 
 The weight lost by the produce of one acre in 
 drying 
 
 32 dr. 
 115.5J 
 
 196020 
 78408 
 
 or lbs. per aci-e 
 
 =12251 
 = 4900 
 
 13782 
 
 7350 
 861 
 
 64 dv. of grass afford of nutritive matter 4.2 dr. 1 
 The produce of the space, ditto - 20.1 </r. 5 
 
 The produce of latter-math is 
 
 Grass, 18 or. The pi-oduce per acre - - 196020 0=12251 4 
 64 «/r. of grass afford of nutritive matter \ dr. SU62 13 = 191 6 31 
 
 The proportional value which the grass of the latter-math bears to that at 
 the time of flowering, is as 4 to 18. 
 
 XXX. Cyitomi-us cristatns. Engl. Bot. 316. Host. G. A. 2, t. 96. 
 Ci-ested dog's-tail grass. 
 
 At the time of flowering, the produce from the brown loiun, with ma- 
 
 YMVC, is 
 
 Grass, 9 or. The produce per acre 
 
 80 dr. of grass weigh when dry - 24 dr. \ 
 
 The produce of the space, ditto - 43 dr. [ 
 
 The weight lost by tlie produce of one acre in 
 drying 
 
 oz. or lbs. per acre 
 
 0= 6125 10 
 
 29403 = 1837 11 
 
 64 dr. of grass afford of nutritive matter 4.1 dr.\ 
 The produce of the space, ditto ^"tV J 
 
 At the time the seed is ripe the produce is 
 
 Grass, 18 oz. The produce per acre 
 SO dr. of grass weigh when dry - 32 dr. ") 
 
 'l"he produce of tlie space, ditto 115.0-*, 3 
 
 I'lie weight lost by the proilucc of one acre ir\ 
 drying - - - 
 
 4287 15 a 
 6508 7 == 406 13 7 
 
 196020 =12251 
 78408 = 4900 
 
 4 
 
 
 7350 12 
 
6806 
 
 4 
 
 
 
 1871 
 
 11 
 
 8 
 
 4934 
 
 8 
 
 8 
 
 239 
 
 4 
 
 8 
 
 9528 
 
 12 
 
 
 
 2858 
 
 10 
 
 
 
 6670 
 
 2 
 
 
 
 148 
 
 14 
 
 o 
 
 APPENDIX. 273 
 
 ez. or lbs. per acre 
 
 64 dr. of f^ass afford of nutritive matter 2.2 <fr. 7 ^g^- q^ ^^g g q 
 The produce of the space, ditto. 11.1 r/r. 5 ^ 
 
 The weight of nutritive matter wliich is lost by 
 takintf the crop at the tune of flowering, ex- 
 ceeding one-sixth of its v;due 71 12 9 
 
 XXXI. Jivena pratends. Engl. Kot. 1204. Fl. Dan. 1083. 
 Meadow oat-grass. Nat. of Britaui. 
 
 At the time of flowering, the produce from a rich sandy loam, is 
 
 Gra^s, 10 ox. The produce per acre - - 108900 = 
 
 80 dr. of grass weigh when dry 22 dr. > 9004.7 o 
 
 Thf produce of tiie space, ditto 44 dr. > ^-^y*' ^ — 
 
 Tlie wt-igiit lost by the produce of one acre in Irving 
 
 64 </r. of grass afford of nutrive matter 2.1 dr. ) "Ri^q « 
 
 The produce of the space, ditto 5.2^ 5 "^^^^ " " 
 
 At the time the seed is ripe the produce is, 
 Grass 14 oz. The produce per acre 152460 = 
 
 80 dr. of g-rass ueigh when dry 2'^ dr. 7 a'-'^ih n 
 
 The produce of tiie space, ditto 67.0| 5 ^» u = 
 
 Tlie weight lost by the produce of one acre in drying 
 
 64 dr. of grass afford of nutritive matter 1 dr. ') o^qo " 
 
 The- produce of tiie space, ditto .'3.2 dr 3 ■'JO'* ^ — 
 
 The weight of nutritive matter which is lost by 
 leavmg the crop till the seed be ripe, exceed- 
 ing one third part of iis value - - 90 6 
 
 The proportional value which the crops, at the time the seed is ripe, bear 
 to that at the time of flowering, is as 4 to 9. 
 
 XXXII. Bromug multiftorus. Engl. Bot. 1884. Host. G. A. 1, t. 11. 
 
 Many flowering brome-grass. Nat. of Britain. 
 
 At the time of flowering, the produce fi*om a clayey loam Is 
 
 Grass, 33 oz. the produce per acre 359370 = 22460 10 
 
 SO </r. of grass weigli when dry - A4 dr. ) ,r,-,/--o p 10-. -<j « o 
 
 'I'he produce of the space, ditto 29u.0| $ -^'"''^ i> -^ i.ioo^ b « 
 
 The weigiit lost by the produce of one acre in drying 10107 4 8 
 
 64</r. of grass afford of nutritive matter 5 dr. \ oony- .0 i-r-A -n ■,<:t 
 
 The produce of 'the space, ditto 41.1 5 ^"^'^■^ ^^ ~ 1/^4 11 12 
 
 This species is annual, and no valuable properties have as yet been disco- 
 vered in the seed. It is only noticed on account of its bemg frequently found 
 in poor grass lands, and sometimes in meadows. It appears from tlie above 
 particulars to possess nutritive powers equal to some of the best perennial 
 kinds, if taken when in flower ; but if left till the seed tie ripe (which, from 
 its early growth, is frequently the case,) the crop is comparatively of no value 
 the leaves and straws being then completely dry. 
 
 XXXm. Festuca loliacea. Curt. Lond. Engl. Bot. 1821. 
 Spiked fescue grass. Nat. of Uritain. 
 
 At the time of flowering, the produce from a brown rich loam, is 
 
 Grass, -24 02. the produce per acre - - 261360 0=16335 
 
 80 Jr. of grass weigh when dry 35 </r. "J i^^nAs n t,^/: 
 
 The produce of the space, ditto 168 dr. $ ^**^*^ = 7146 
 
 The weight lost by the ])roduce of one acre in drj-ing 9188 
 
 64 Jr. of grass afford of nil tritive matter 3 dr. "> ir,n«, j 
 
 The produce of the space, ditto 18 Jr. j ^^^^ * "= 7&5 11 
 
 M m 
 
 
 
 
 
 9 
 
 
 
 7 
 
 
 
274 APPENDIX. 
 
 At tlie time the seed is ripe, the produce is 
 
 or. or lbs. per aci-e 
 
 Grass, 16 oz. the produce per acre 174240 = lOS'K) 
 
 80 ^/r, of grass weis,'h when dry 33 dr. > 71874.0 4492 2 
 
 The produce of tlic space, ditto lOSy 5 
 
 The weight lost by the produce of one acre in drying- 6397 14 
 
 ()4 (//-. of grass afiord of nutritive matter 3.1 dr. \ hrah o =» 55" 2 
 Tlie prochice of the space, ditto 13 dr. 5 
 
 The latter-math produce is 
 Grass, 5 oz. The produce per acre - - 54450 = 3403 2 
 
 64 dr. of grxss afford of nutritive matter 1.1 dr. 1063 7 = 66 7 7 
 
 The weigiit of oytritivc matter which is lust by 
 leaving tlie cro|) till the seed be ripe, exceed- 
 ing one fourth part of its value -..--. 212 11 
 
 The proportional value which the grass, at the time of flowering, bears to 
 that at the time the seed i-i ripe, is as 12 to 13 ; and the value of the latter- 
 math stands ih proportion to tliat of the crop at the time of flowering, as 5 to 
 12, and to that of the crop taken at the time the seed is ripe, as 5 to 13. 
 
 This species of fescue greatly resembles the rye grass, in habit and 
 place of growth : it has excellencies which make it greatly superior to that 
 grass, for the pur[)oses of either hay or permanent pasture. This species 
 seems to improve in produce in proportion to its age, which is directly the re- 
 verse of the Lolium pereime. 
 
 XXXIV. Poa cristata. Host. G. A. 2, t. 75.— Aira Cristata. Engl. Bot. 648. 
 Crested meadow grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a sandy loam is 
 
 ox. or lbs. per acre 
 
 Grass, 16 or. The produce per acre - - 174240 = 10890 
 80 ^r. of grass weigh when dry 36 rfr ^ ^g^g q = 4900 Si 
 
 Ihe produce oi the space, ditto H^TB" j 
 
 The weight lost by the produce of one acre in drying - - 5989 8 
 
 64 r/r. of grass afford of nutritive matter 2 dr. 'i e/tAe n lAri K Q 
 
 The produce of the space, ditto 8 dr. 5 ^'**^ U — JW ^ u 
 
 The prochice of this species, and the nutritive matter that it affords, are 
 equal to those of the Festuca ovina at the time the seed is ripe : they equally 
 delight in dry soils. The greater bulk of grass in proportion to tlie weight, 
 with the comparative coarseness of the foliage, render the Poa cristata infe- 
 rior to the Festuca ovina. 
 
 XXXV. Festuca mijiirus. Engl. Bot, 1412. Host. G. A. 2, t. 93. 
 Wall fescue grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a light sandy soil is 
 
 oz, or Jbs. per acre 
 
 Grass, 14 oz. The ])roduce per acre - - 152460 
 80 dr. of grass weigh when dry 24 dr. "i ^c-oo n. 
 
 The produce of the space, ditto 67||y 5 ^^'"^^ " 
 
 The wt ight lost by the produce of one acre in drying - 
 64 rfr. of grass afford of nutritive matter 1.2 </r. } "^/q a, 
 The produce of the space, ditto 5.1 </r. $ "^ 
 
 This species is strictly annual ; it is likewise subject to the nist; and the 
 above being its whole produce for one year, it ranks as a very inferior grass. 
 
 XXXVI. Mra flexuosa. Engl. Bot. 1519. Host. G. A. 2, t. 43. 
 Waved mountain hair-grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a heath soil is 
 
 oz. or lb». per acre 
 
 Grass, 12 oz. The produce per acre - - 130680 8167 8 (J 
 
 9528 
 
 12 
 
 
 
 2858 
 
 10 
 
 
 
 6670 
 
 2 
 
 
 
 223 
 
 5 
 
 4 
 
APPENDIX. 275 
 
 oz. or lbs. per acre 
 
 80rfr,of ^asswe5ghwhendry - 31 ^/r.^ ? 5^638 0=3164 14 8 
 The produce of the space, ditto - 74y S 
 
 The weigiit lost by the produce of one acre in drying - - 5002 9 8 
 64 f/r. of prass afford of nutritive matter \.2 dr. > 3062 13 191 6 13 
 
 The produce of the space, ditto 4.2 dr. ) 
 
 XXXV^II. ffordeitm hulbomm. Hort. Kew. 1, P. 179. 
 
 Bulbous barley grass. Nat. of Italy and the Levant. Introduced 1770, by 
 
 Mons. Richard. 
 
 I 
 
 At the time of flowering, the produce from a clayey loam with manure, is 
 
 ' OS, or lbs. per acre 
 
 Grass, 35 oz. The produce per acre - - 381150 =23821 
 
 80 ./r. of grass weigh when dry - 93 ./r. 7 ^^.^^224 q = 9826 8 6 
 The produce or tlie space, ditto - 2:>l dr.- 3 
 
 The weight lost by tlie produce of one acre in drying - - 13994 7 10 
 
 64 </r of grass afford of nutritive matter 3.2 ^A". } 20844 2 1302 12 2 
 The produce of the space, ditto - 30.2 1 5 
 
 XXXVIII. Festuca calamaria. Engl. Bot. 1005. 
 Reed-like fescue grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a clayey loam is 
 
 Grass 80 oz. The produce per acre 
 80 dr. of grass weiglit when dry 28 dr. 7 
 
 The produce of the space ditto - 448 dr. 3 
 The weightlostby the produce of one acre in drying 
 64 dr. of grass afford of nutritive matter 4.2 dr. > 
 The produce of the space, ditto - 90 dr. 5 
 
 At the time the seed is ripe the produce is 
 Grass, 75 oz. The produce per acre ... 
 80 dr. of grass weigh when dry 19 dr. '} 
 
 The produce of the space, ditto 283 dr. 3 
 
 The weight lost by the produce of one acre in drying - 
 64 dr. of grass afford of nutritive matter 3 dr. ^ 
 The produce of the space, ditto 56,1 dr. 5 
 
 The weight of nutritive matter which is lost by 
 
 leaving the crop till tiic seed be ripe, being 
 
 nearly one third part of its value 1435 11 2 
 
 The proportional value which the grass of the time the seed is ripe, bears 
 to that, at the time of flowering, is as 12 to 18. 
 
 This grass, as has alrea<ly been remarked, produces a fine early foliage in the 
 spring. The produce is very great, and \U nutritive powers are considerable. 
 It appears, from the above particulars, to be best adapted for hay. A very sin. 
 gular disease attacks, and so'Tietimes nearly destroys the seed of this grass : 
 the cause of this disease seems to be unknown ; it is denominated Clavus, by 
 some ; it appears by the seed swelling to three times its usual size in length 
 and thickness, and the want of the carcle. Dr. VVilldenow describes f wo dis- 
 tinct species of it : 1st, the simple clavus, which is mealy and of a dark colour, 
 without any smell or taste ; 2d, the malignant clavus, which is violet blue, or 
 blackish, and internally too has a bluish colour, a ftetid smell, and a sharp pun- 
 gent taste. Bread made from grain affected with this last species, is of a bluish 
 colour ; when eaten, produces cramps and giddiness. 
 
 XXXIX, Bromus liltormts. Host. G. A. P. 7, t. 8, 
 
 Sea-side brome grass. Nat. of Germany, grows on the banks of the Da- 
 nube and other rivers. 
 
 At the time of flovvenng, the produce from a clayey loam is 
 
 oz. or Ibx. per acre 
 
 Grass, 61 oz. The produce per acre - - - 6642&0 =41518 2 
 
 oz. 
 871200 
 
 
 
 or lbs. per acre 
 = 54450 
 
 304920 
 
 
 
 = 19057 8 
 
 
 
 . 
 
 . 
 
 35392 8 
 
 
 
 61256 
 
 4 
 
 = 3828 8 
 
 4 
 
 816750 
 
 
 
 =51046 14 
 
 
 
 193978 
 
 2 
 
 =12123 10 
 
 
 
 s - 
 
 . 
 
 38923 4 
 
 
 
 38285 2 
 
 =2392 13 
 
 2 
 
276 
 
 APPENDIX. 
 
 oz. or Ibsi per acne 
 
 80 r/r. of grass weiffh when dry - 41 rfr. / o^o.^o ,/^ r.. wr> « .« 
 Ti.e p.oauce of the si)ace, ditto - 50U«^ \ "^^^^^S 10 ==21:>78 10, 
 
 The weight lost by the produce ot'one acre in drying 
 64 (//'. ot )<rass afford ot" nutritive matter l.J dv. 
 The prodnce ot the space, ditto 22.3J 
 
 At the; time the seed is ri[)e, the produce is 
 Grass, 56 oz. The produce per acre 
 8U dv of ffrass vveij;h when dry 32 dr. 
 
 The prochice of tl»e space, (htto 358| 
 
 The weig'iit lost by tlie pnxhice of one acre in drying 
 64 (Iv. of grass afford of nutritive mailer >.<! ilr. ^ 
 Tile prochice of ti>e spuce, (htto 196 dr. 3 
 
 Tlie weig-i\t of nuti-ilive matter which is lost by 
 taking the cro]) at the time of flowering, 
 eJJceeding one half of its value - ... - 1111 5 6 
 
 The proportional value which the grass at the time of flowering bears to 
 that at the time the seed is ripe, is as 6 to 14. 
 
 Tiiis species greatly resembles the preceding in habit and manner of 
 growth ; but is inferior to it in value, which is evident from the deficiency of 
 its produce, and ol tiu' nutritive matter afforded liy it. The whole plant .is 
 likewise coarser and of greater bulk m j)roporlion to its weight. The seed 
 is alfecied with the same disease which destroys that of the former spe- 
 cies. 
 
 - 
 
 - 
 
 20540 
 
 1 
 
 6 
 
 15567 
 
 4 
 
 = 973 
 
 1 
 
 4 
 
 6U9840 
 
 
 
 =38115 
 
 
 
 
 
 243936 
 
 
 
 =15246 
 
 
 
 
 
 
 - 
 
 22869 
 
 
 
 
 
 33350 
 
 
 
 = 2084 
 
 6 
 
 10 
 
 XL. Festnca eliator. Engl. Rot. 1593. Host. G. A. 2, t. 79. 
 
 Tall fescue grass. Nat. of liriiain. 
 
 At the time of flowering, the produce from ablack rich loam, is 
 
 oz, or lbs. per acre 
 
 Grass, 7S oz. The produce per acre 
 80 </;•. of grass weigh when dry - 28 dr. ') 
 
 . 'i'he proiUicc of the space, ditto • 420 dr. $ 
 The weight which is lost by the produce of one ) 
 acre in drying .--..- 3 
 64 (/;•. of grass afford of nutritive matter 5 dr. } 
 Tlie produce of the space, ditto - 93.3 dr.y 
 
 816750 
 285862 
 
 =51046 14 
 
 8 -17866 6 8 
 
 33180 7 8 
 
 63808 9 — 3988 9 
 
 816750 
 285862 
 
 =.51046 4 
 8 =17866 6 
 
 3 dr. I 
 
 38285 2 
 
 33180 7 
 ' 2392 13 
 
 At the time the seed is ripe the produce is 
 Grass, 75 or. The produce per acre 
 80 <fr. of grass weigh when dry - 28 dr. 
 
 The produce of the space, ditto 420 dr 
 
 The weight lost by the produce of one acre in 
 
 dryii g . - . - • 
 
 64 dr. of gTass aflbrd of nutritive matter 3 
 The produce ot' the space, ditto - ^^ , 
 
 The weight of nutritive matter which is lost by'leaving the crop 
 
 till the seed be ripe, exceechng one-tliird part of its value 1595 3 7 
 
 The proportional value which the grass at the time the seed is ripe, bears 
 to that at the time of flowering, is as 12 to 20. 
 
 The prodvice of latter-math is 
 (irass, 23oi. The produce per acre - - 250470 0=15654 6 
 64 dr. of grass aflbrd nutritive matter 4 dr. - 156,i4 6 = 978 6 6 
 
 The proportional lalue which the grass of the latter-math bears to that of 
 the crop, is as 16 to 20 ; and to that at the time the seed is ripe, as 12 to 16, in- 
 verse. 
 
 This species of fescue is closely allied to the Festnca pratensin, from which 
 it diife.rs in little, except t!iat it is larger in every rtspect. The produce is 
 nearly three times that of the F. fttatcii.v.s. and the nutritive powers of the 
 grass arc superior in direct proportion, as 6 to 8. 
 
APPENDIX. 277 
 
 XLI. J^rnrdva stricta. Eng. not. 290. Host. G. A. 2, t. 4. 
 Uprifj^ht mat-grass. Nut. of IJritain. 
 
 At the time the seed is ripe the produce is 
 
 oz. or lbs. per acre 
 
 Grass, 9 oz. The prorhice per acre - - 98010 = 6125 10 
 
 80 dr. of cfrass wei^h when dry - 32 t'"- > .->mA^ « « ^ 
 
 Th.^ produce of th<- space, ditto - 57 2} ^ = 24o0 4 
 
 The v/cifi^ht lost by the produce of one acre i'l drying 3675 6 
 
 64 f/r. of grass afford of nu'ritive matter 2.1 '^r.^ oa^c in •.•^ ^r -r. 
 
 The produce of the space, ditto - 5.0J j 3445 10-= 215 5 10 
 
 XLII. Triticnm, Sp. 
 Wheat grass. 
 
 At the time of flowering, the produce from a rich sandy loam is 
 
 oz. or lbs. per acre 
 
 Grass, 18 oz. The produce per acre - . - 196020 =12251 4 
 SO (h'. of grass w^igh when drv - 33 '/'"O 
 
 the produce of the space, ditto - 115^ S ~^'*^^ = 4900 8 
 
 Tlie weight lost by the produce of one acre in drying - 7350 12 
 
 64 </r. of grass afforil of nutritive matter 2.2 /•/»•. ) 7fi«7 n /17k q a 
 
 The produce of the space, ditto - 11.1 Jr. 5 ' ' u =- *^e y O 
 
 XLIU. Festncafuitans. Curt. Lond. Engl. Bot. 1520. Poa fluitans. 
 Floating fescue grass. Nat. of Britain. 
 
 At the time of flowering, tlie produce from a strong tenacious clay, is 
 
 oz. or lbn. per acre 
 
 Crass, 20 or. The produce per acre - - 217800 0=^13612 8 
 80 r/r. of grass weigli when dry - -24 Jr./ g^ 4fis<> to n 
 
 The produce of the space, ditto - - 96 Jr. $ °'^'^^" = 4083 12 
 The weiglit lost by the pt'oduce of one acre in drying - - 9528 12 
 64 J;-, of grass afford of nutritive matter l.o Jr. ? ^^q^ ^ „ „ 
 
 The produce of the space, ditto - 8.3 Jr. S ^^ = o72 o 7 
 
 The above produce was taken from grass tliat liad occupied the ground for 
 four years, during wliich time it had increase<l every year; it tlierefore ap- 
 pears contrary to what some have supposed to be capable of being cultivated 
 in perennial pastures. 
 
 WAV. nolcmbtnatnu. Curt. Lond. El. Dan. 1181. 
 
 Meadow soft grass. Yorkshire grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a strong clayey loam is 
 
 oz. or Ihn. per acre 
 
 Grass, 28 oz. The produce per acre - . 304920 0=19057 8 
 80 Jr. of grass weigh wiuMi dry - 26 rfr. ") m^toc ia cr^r, « ... 
 
 The produce of the space, ditto - 157.2? $ 106585 14=6661 9 14 
 The weight lost by t!ie produce of one acre in drying - - lj395 14 2 
 fi-l Jr. of grass afford of nutritrve matter 4 Jr. ) ,„.,,_ q ,,„, , „ 
 'i'he produce of the space, ditto - 28 Jr. 3 ^^^^' 0=1191 1 8 
 
 At the time the seed is ripe, the produce is 
 
 Grass, 28 or. The produce per acre • - 304920 ==19057 8 
 80 Jr. of grass vveigli when dry - 16 </r. ^ 
 
 Ihe produce of the space, ditto - 89.;^ 5 0^984 0=3811 8 
 
 The weight lost by the produce of one aorc m drying - - 15246 
 
 64 dr. of grass afford of nutritive matter 2. > dr. ? ijino => 818 14 • 
 The produce of the space, ditto - 19.1 Jr. 5 
 
278 APPENDIX. 
 
 Uc. per acre 
 The weight of nutritive matter which is lost by leaving the crop 
 
 till the seed be ripe, exceeding one-third part of its value - 372 3 8 
 The proportional value which the grass at the time the seed is ripe, bears 
 to that at tlie time of flowering, is as 11 to 12. 
 
 XLV. Festuca ditmelorum. Flo. Dan. 700. 
 
 Pubescent fescue grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a black sandy loam, is 
 
 oz. or lbs. per acre 
 
 Grass, 16 oz. The pr :duce per acre - - 174240 =10890 
 
 80 rfr. of grass weigh when dry . - - 40 dr."} q-,oA n -a Mr n n 
 
 The produce of the space, ditto - 120 Jr. 5 ^^^^0 = o44.5 9 
 The weight lost by the produce of one acre in 
 
 drying - -' 5445 
 
 64 </r. of grass aflTord of nutritive matter Ir/r. "> __„ „ im o c 
 
 The produce of the Si >ace, ditto - - 4 Jr. 5 ^'^^ " "^ UU ^ a 
 
 XLVI. Poafirtilis Host. G. A. 
 
 Fertilis meadow grass. Nat. of Germany. 
 
 At the time of flowering the produce from a clayey loam, is ' 
 
 oz. or lbs. per acre 
 
 Grass, 22 oz. The produce per acre - - 239580 =14973 12 
 80 ./,-. of grass weigh when dry - ' ff'l U5779 ^ = 78&1 3 8 
 The produce 01 the space, ditto - lo4y 3 
 
 The weiglit lost by the produce of one acre in 
 
 drying --..-..--- 7111 8 8 
 
 64rfnof grass afford of nutritive matter 4 2 Jr. ^ jjg845 7 _ io52 13 7 
 The produce of the space ditto - 24.3 dr. 5 
 
 If the nutritive powers and produce of this species, be compared with any 
 other of the same family, or sucli as resemble it in habit and the soil which it 
 affects, a superiority will be found, which ranks this as one of the most valuable 
 grasses ; next to the Poa angitstifolia, it produces the greatest abundance of 
 early foliage, of the best quality, which fully compensates for the comparative 
 lateness of flowering. 
 
 XLVII. Jlrundo colorata. Hort. Kew. I.P. 174. Engl. Bot, 402. Phalaris 
 ai'iuidinacea. 
 Striped-leaved reed grass, Nat. of Britain. 
 
 At the time of flowering, the produce from a black sandy loam is 
 
 oz. or lbs. per acre 
 
 Grass, 40 or. The produce per acre - - 435600 0=27225 
 
 80 f/r. of grass weigh when dry 56 dr.'> mcnon n i99ci A. n 
 
 The produce ofthe space, ditto - 28.8 Jr. 5 ^^^^^^ 0=12251 4 
 
 64 Jr. of grass afford of nutritive matter . 4 Jr 7 otooc n I7ni Q n 
 
 The produce of the space, ditto - 40 Jr. 5 '^'^^^ u = i/'ui y u 
 
 The strong nutritive powers which this grass possesses recommend it to 
 the notice of occupiers of strong clayey lands, which cannot be drained. Its 
 produce is great, and tlie foliage will not be denominated coarse, if compared 
 with those which afford a produce equal in quantity. 
 
 XLVm. Trifolmm prntmse. W. Bot. 3, P. l."7. 
 
 Broad-leaved cultivai ed clover. Nat of Britain. 
 
 At the time the seed is ripe flower, the produce from a rich clayey 
 loam is 
 
 oz. or lbs. per acre 
 
 Grass, 72 oz. The produce per acre - - 784080 =49005 
 
APPENDIX. 
 
 279 
 
 80 dr. of grass weigh when dry - 20 dr. 7 
 
 The produce of the space, ditto - 288 dr. $ 
 
 The weight lost by the produce of one acre in 
 
 drying - - 
 
 64 dr. of grass afford of nutritive matter 2.2 dr. 
 The produce of the space, ditto - 45 dr, 
 
 9z. «F lbs. per acre 
 
 196020 =12251 
 
 30628 2 
 
 3675 
 1914 
 
 If the weight which is lost by the produce of this species of clover, in 
 drying, be compared with that of many of the natural grasses, its inferior va- 
 lue for the purpose of hay, compared to its value for green food, or pasture, 
 will appear ; for it is certain that the difficulty of making good hay increases 
 in proportion with the quantity of superfluous moisture which the grass may 
 contain. Its value for green food, or pasture, may further be seen by com- 
 paring its nutritive powers, with those manifested by other plants generally 
 esteemed best for this purpose. 
 
 Trifolium pratense (as above) affords of nutritive matter - 2.2 dr. 
 
 XLIX. Trifolinm ripens (white clover) from an equal quantity of 
 grass •.. 
 
 2.0*. 
 
 L. Ditto, variety, with brown leaves, ditto . - - - . 2.2 dr. 
 Tile grass of the T*. pratense, therefore, exceeds in value that of the T. 
 repens, by a proportion as 8 to 10 ; but it is of equal proportional value with 
 the brown variety. 
 
 LI. Burnit (Poterium sanguisorba) affords of nutritive matter - 2.2 dr. 
 LII. Bunias orientalis (a newly introduced plant,) ditto - - - 2.2 dr. 
 
 The proportional value of these two last, and of the T. pratense, and the 
 brown-leaved variety of T. repens, are equal ; they exceed the T. repens as 8 
 to 10. 
 
 The comparative produce of these four last-mentioned species, per acre, 
 has not been ascertained. 
 
 LIU. Trifolium macrorhizum. 
 
 Long-rooted clover. Nat. of Hungary, 
 
 At the time the seed^is ripe, the produce from a rich clayey loam is 
 
 Grass, 144 oz. The produce per acre 
 80 dr. of grass weigh when dry - 34 <fr. 
 
 The produce of the space, ditto - 979y 
 The weight lost by ihe produce of one acre in 
 
 drying 
 
 64 dr. of grass afford df nutritive matter 2 3 dr. } 
 The produce of the space, ditto - -99 dr. 5 
 
 1568160 
 666468 
 
 67381 14 
 
 or lbs. per acre 
 =98010 
 
 =41654 4 
 
 56355 12 
 = 4211 5 14 
 
 The root of this species of clover is biennial : it penetrates to a great depth 
 in the ground, and is in consequence little affected by the extremes of wet 
 or dry weather. It requires good shelter, and a deep soil. The produce, 
 when compared to that of others that are allied to it in habit, and place of 
 l^owth, proves greatly superior. The following particulars, some of which 
 refer to results stated in the next two pages, will make this manifest : 
 
 Trifolium pratense 
 Broad leaved clover 
 
 Medicago sativa. 
 Lucern. From ia soil of the 
 like nature -^ 
 
 ("Produces per acre. Grass 
 
 < Ditto, Hay, - 
 
 ( Affords do. of nutritive matter 
 C Produces per acre. Grass 
 
 < Ditto, Hay, 
 CAfl[»rds mi nutri^ye matter - 
 
 lbs. 49005 
 12251 
 
 1914 
 707^5 
 28314 
 
 1659 
 
280 APPENDIX. 
 
 Hedysarum ombvycha C Produces per acre. Grass - • - ».. 8R48 
 CAliords oi nutritive matter - - bl4 
 
 The weight of nutritive matter affonled by the produce of the T. 
 macrovhizum, excsreding that of the T. pruteme, in proportion, 
 
 nearly as T to 15 2297 
 
 The uroponionul vahie of the grass of T. pratense to that of T. 
 macrorhiziim, is lU to 11. 
 
 The wcijjht of niitiitlve matter aflTorded by the T. macrorhzuin, ex- 
 ceeding that of the jyiedicago sutiva, in proportion nearly as l3 
 
 tooj - -. - - 2552 
 
 The proportional value of the grass is as 11 to 6. 
 The vveigiit of nutritive matter which is aiibrdcd by the produce of 
 tlie 7'. tiiacror/iizimh, exceeding thp.t of the Hedysarum onobrydiis in 
 
 proportion nearly a£5tofi7 - 3897 
 
 The proportional value of the grass, like that of the 2\ pratense, 
 is as 11 to 10. 
 
 The produce of each of the above-mentioned species was taken from a 
 similar soil, and in the same situation, the conchisions must thereture be con- 
 sidered positive, with respect to such soils only. It is evident that more than 
 twice the quantity of nutritive matter is afibrded by the produce of one acr« 
 of the T. macruvldzuiii, than from the produce ot an equal space covered by 
 the T. prutense. Us short diuation in the soil (for it sown early in the au- 
 tumn, on a rich light soil, it is oidy an annual plant) renders it lit only for 
 green food or hay ; this in some measure lessens its value, when compared 
 with the T. pratense. It possesses tlie essenUal property of aflordini^ abun- 
 dance of good seed ; and if the ground be kept clear of weeds, it sows itself, 
 vegetates, and grows rapidly, without coveringin, or any operation whatever. 
 For four years it has propagated itself in tl'is manner, on the space of ground 
 which it now occupies, and from wliich tli;s statement of its comparative va- 
 lue is made. The produce of lucern in grass, comes nearer to this species in 
 quantity, but is gTeath deficient in nutritive matter, as much as 13 to 33. 
 The long conthiuance of hicern in the soil is therefore the onU merit which 
 it possesses above the two last-itientioned species ; and when that is the object of 
 the cultivator, it will of necessity have the preference. 
 
 The value of the grass of saintfoin is ecjual to tliat of the T. pratense ; and 
 projiortionally less than that of the TrifAu/m macrorfdzimi, as 10 to .11. The 
 quantity of gTass is very small, and on soils of the nature above described, it 
 is doubtless inferior. However, from the superior vaiue oi ciie gra^.s, on dry 
 hilly situations or chalky soils it inaj' in such situations possibly be their supe- 
 rior in every respect. 
 
 LIV. Medic/igo Saliva. Wither. B. 3, P. 643. 
 Lucern. Nat. of Britain. 
 
 At the time the seed is ripe, the produce frcm a rich ckiyer loam is 
 
 oz or lbs. per acre 
 
 Grass, 104 oz The produce per acre - - 1132560 =-70785 
 
 80 c/,^r,fgrass weigh when dry - "i^? ,<"••? 453024 0-28314 
 The produce of the space, ditto - 66D.Cf 5 
 The weight lost by the produce of one acre in 
 
 dicing . . - 42471 
 
 64 f/r. of gr.t.ss afibrd of nutritive matter 1.2 dr. 1 nc:-AA c -jt^-n a c 
 
 The produce of the space, ditto - 39 ./,-. $ ^^^"^ 6 = 7bo9 6 
 
 LV. Hedysanmi onobrychis. Wither. 3. P. 628. 
 Saintfoin. Nat. of Britain. 
 
 At the time the seed is ripe; the produce from a rich clayey loam is 
 
 oz. or lbs. per acre 
 
 Grass, 13 as. The produce per acre - . 141570 == 8848 2 
 
oz. 
 130680 
 
 
 
 _- 
 
 lbs. per acre 
 8167 8 
 
 52272 
 
 
 
 = 
 
 3267 
 
 
 
 
 
 . 
 
 
 . 
 
 4900 
 
 8 
 
 
 
 7657 
 
 
 
 ^ 
 
 478 
 
 9 
 
 
 
 APPENDIX. 281 
 
 oz- or lbs. per acre 
 
 80 f/r. of grass weigh when dry - 32 '/'•• > ^gggS = 35J9 4 
 
 I'he produce of Uie space, ditto - 83-5- 3 
 
 Tlie wciarlit lost by tiie produce of one acre in 
 
 drying - - - - - 5308 14 
 
 64 dr. of grass afford of nutritive matter 2.2 dr. ') ^^^q j^ ^ 045 IQ 1 
 
 The produce of the space, ditto - 8.04 > 
 
 LVl. Ifordeiim pratense. Engl. Bot. 409. Host. G. A. 1. 1. 33. 
 Meadow barley-grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a brown loam, with manure, is 
 
 Grass, 12 oz. The produce per acre 
 80 dr. of grass weigh wlien dry - 32 dr. ■) 
 
 The [)roduce of the space, ditto - 67.1 dr.^ 
 The weight lost by the produce of one acre in ■ 
 
 drying - - - - - 
 
 64 dr. of grass afford of nutritive matter 3.3 dr. ^ 
 The produce of the sp;.; c^ ditto - 11.1 dr. 3 
 
 LVII. Poa compressa. Engl. Bot. 365. 
 
 Flat-stalked Meadow-grass. Nat. of Britain, 
 
 At the time of flowering, tlie produce from a gravelly soil, with manure, is 
 
 oz. or lbs. per acre 
 
 Grass, 5 oz. The produce per acre - - 54450 = 3403 2 
 80 ,/r. of grass Avcigh when dry - 34(/r.J 23^^^ 4 = 1446 5 4 
 
 The produce or tlve space, ditto - o4 dr. > 
 The weight lost by the produce of one acre in 
 
 drying - '- 1956 12 12 
 
 64 dr. of grass afford of nutritive matter - 5 dr. > .2^0 ^^ ^ 265 13 14' 
 The produce of the space, ditto - 6.1 5 "^ •■ 1 
 
 The specific characters of this species are mucli the same as those ot the 
 roafc-rtilis, differing in the compressed figure of the straws and creeping 
 root onlv. If the produce was of magnitude, it would be one of the most 
 valuable" grasses ; for it produces foliage e^rly in the spring, and possesses 
 strong nutritive powers. 
 
 LVIII. Poa aqiialica. Curt. Lond. Engl. Bot. 1315. 
 Heed Meadow-grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a strong tenaciou.s clay, is 
 
 oz. or lbs. per acre 
 
 Grass, 186 oz. The produce per acre - - 20225540 .==126596 4 
 
 SO Jr. of grass weigh when dry - 48 f/i-. ^ 1215324 = 75957 12 
 
 The produce of the space, ditto - 1785.2^^. S 
 l"]je weight lost by the produce of one acre in 
 
 drying 
 
 50638 8 
 
 64 dr. of grass afford of nutritive matter 2.2 dr. } 7C)122 = 4945 2 10 
 
 The pro hice of tlie space, ditto - 116.1 dr. j 
 
 LIX. ^ra aqnatica. Curt. Lond. Engl. Bot. 1557- 
 Water hair grass. Nat. of Britain. 
 
 \t tlie time of flowering, the produce from water, is 
 
 oz. or lbs. per acre 
 
 (h-ass, 16 oz. 'I-he produce per acre - - 1742400 ---= 10890 
 
 N II 
 
282 APPENDIX. 
 
 oz. or iis. per acre 
 
 80 rfr. of grass weigh when dry - 24*0 o = "^^fiT .. o 
 
 The produce of the space, ditto - 76.3,V 5 ' 
 
 The weighi lost by the produce of one acre in 
 
 drying - - 7623 
 
 64 (//■. fff grass afford of nutritive matter 2.1 dr.'i - _ ^ „„_ .,„ ^(. 
 
 Tiie produce of the space, ditto - 9 dr. $ , ^ ^ 
 
 LX. Brotniis cristatus. Triticum cristatum, H. G. A. 2, t. 24. 
 Secale prostratum. Jacquiu. Nat. of Germany. 
 
 At the time O'' flowering', the produce from a clayey loam, is 
 
 oz. or lbs. per acre 
 
 Grass, 13 oz. The produce per acre - - 141570 = 8848 
 
 80 Jr. of grass weigh when dry - - o6dr.\ rt:cno a ^.-on a n 
 
 The produce of the space, ditto - 83.1 dr. ^ ^^°^^ = od>3U * U 
 The weight lost by the produce of one acre in 
 
 drying - - 5308 14 
 
 64 J)', of grass afford of nutritive matter 2.2 dr.'i re^n i "At: in n 
 
 The produce of the space, ditto - 8.0^?^ ^ ^^"^ '■ = ^*^ ^" ^ 
 
 LXI. Elyrmis Sibiricus. Hort. K. 1, P. 176. Cult. 1758, by William P. Millar. 
 Siberian lyme grass. Nat. of Siberia. 
 
 At the time of flowering, the produce from a sandy loam, with manure, is 
 
 oz. or lbs. per acre 
 
 Grass, 24 oz. The produce per acre ' - - 261360 = 16335 
 
 80 d,-. of grass weigh when dry - -^S^-] 91476 = 5717 4 
 The produce ot the space, ditto - lo4.1j 3 
 The weight lost by the produce of one acre in 
 
 drying ,- 10617 12 
 
 64 rf)\ of grass afford of nutritive matter 2.1 dr.'i 91 SR 7 = 511 7 
 The produce of the space ditto - 13.2 dr. $ 
 
 fcXII. Mra cxspiiosa. Host. G. A. 2. t. 42. Engl. Bet. 1557. 
 'llirty hair grass. Nat. of Britain. 
 
 At the time the seed is ripe, the produce from a strong tenacious clay is 
 
 oz. or lbs. per acre 
 
 Grass, 15 oz. The produce per acre - - 163350 6 =10209 6 
 80 rf,-. of grass weigh when dry - -26rfr.7 53088 12=3318 12 
 1 he produce ot the space, ditto - ^'^^■r ^ 
 
 The weiarht lost by the produce of one acre in 
 
 drying -...------ ooyi 5 4 
 
 64 (/)•. of grass afford of nutritive matter 2 dr.\ e^\{^^ \y = 319 11 
 The produce of the space, ditto - 7.2 dr. 3 
 
 LXni, Hordeum murinum. Curt. Lond. Engl. Bot. 1971. 
 Wall barley grass. Way Bennet. Nat. of Britain. 
 
 At the time of flowering, the produce from a clayey loam, is 
 
 oz. or lbs. per acre 
 
 Grass, 18 oz. The produce per acre - - 196020 0=12251 4 
 80 dr. of grass weigh wlieii dry - 28 dr. } gggQj, q _ ^287 15 
 
 The produce of the space, ditto 100.O.J. 3 
 
 The weight lost by the produce of one acre in 
 
 drying . " - - - , 7963 5 
 
 64 Jr of grass afford of nutritive matter 3 dr.'i 2679 15 = 167 7 15 
 The produce of the space, ditto - ^-^^g ^ 
 
APPENDIX. 283 
 
 LXIV. Avena flavesceiis (Jurt. Lond. Engl. Bot. 952. 
 Yellow oat grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a clayey loam, is 
 
 oz. or Ibs^tv acre 
 
 Grass, 12 oz. The produce per acre - - 130680 ' = 8157 8 
 80 Jr. of Krass weigh when dry - 28 J,..-> ^.^„g 0=2858 10 
 
 1 he produce ot the space, ditto - o/.l dr. 3 
 
 The weight lest by the produce of one acre in 
 
 dtying - 5308 14 
 
 64 c/r of grass afford of nutritive matter 3.3 </n^ •vp.r'r n A78 Q n 
 
 The produce of the space, ditto ll.l dr. S '^^' "~ 
 
 At the time the seed is ripe the produce is 
 Grass, 18 OS. The produce per acre - - 196020 0=12251 4 
 80 rfr. of grass weigh when dry - 32 *0 ^^^^ 0=4900 8 
 
 The produce of the space, ditto - 115.0y 5 
 The weight lost by the produce of one acre in 
 
 drying ...- - 7350 12 
 
 64 r/r of grass afford of nutritive matter 2.1 rfr.^ gg^. ^ _ ^30 ^l. 5 
 
 The produce of the space ditto - IO.O5 5 
 
 The weight of nutritive matter which is lost if the crop be left till 
 
 the seed be ripe, exceeding oue-tenl!i part of its value - 47 13 11 
 
 The proportional value which the grass, at the time the seed is ripe, bears 
 to that at the time of flowering is as 9 to 15. ^ 
 
 The produce of latter-math is 
 
 Grass, 6 oz. The produce per acre - - 65340 = 4803 12 
 
 64 i/r. of grass afford of nutritive matter 1.1 </r. 1276 2 = 79 12 2 
 
 The proportional value which the grass of the latter-math bears to that at 
 the time of flowering, is as 5 to 15 ; and to that at the time the seed is ripe, as 
 5 to 9. 
 
 This species is pretty generally cultivated in many parts of this kingdom ; 
 and it appears from the above details to be a valuable grass, though inferior to 
 many others. 
 
 LXV. Bromiis sterilis. Engl. Bot. 1030. Host. G. A. 1. t. 16. 
 Barren brome grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a sandy soil, is 
 
 oz. or lbs. per acre 
 
 Grass, 44 oz. The produce per acre 479160 =29947 8 
 
 80 ffr. of grass weigh when dry - 45 dr.^i „ ,, ..„ _ j. 
 
 The produce ofthe space, ditto 396 rfr.5 '^'^^527 8=16845 7 S 
 
 The weight lost by the produce of one acre in 
 
 drpng 13102 8 
 
 64. //-.of grass afford of nutritive matter Jdr.J 3^43^ 6=2339 10 
 The produce or the space, ditto - 55 dr. y 
 
 64 dr. of the flowers afford of nutritive matter 2.2 dr. The nutritive powei-s 
 of the straws and leaves are, therefore, more than twice as great as those of 
 the flowers. This species, being strictly annual, is of comparatively little va- 
 lue. The above particulars shew that it has very considerable nutritive pow- 
 ers, more than its name would imply, if taken at the time of flowering ; but if 
 left till the seed be ripe, it is, like all other annuals, comparatively of no 
 value. 
 
 LXVI. Holcua mollis. Curt. Lond. Wither. B. 2. P. 134. 
 Creeping soft grass. Nat. of Britain. » 
 
284 
 
 APPENDIX. 
 
 At the time of flowering", the jModuce fVom a sandy soil, is 
 
 544500 
 217800 
 
 or lbs. per acre 
 
 
 in 
 
 =34031 4 
 =13612 
 
 8 
 
 20418 12 
 2 = 2392 13 
 
 357590 
 135036 
 
 =21099 
 = 8439 
 
 6 
 12 
 
 Grass, 50 oz. The produce per acre 
 80 (Ir of g-rass weigli whgn dry - 32 dr. 
 
 The proi^uce of the space, ditto 320 dr. 
 
 The weigl)t lost by the produce of one acre in 
 
 drying- .._..- 
 
 64 dr. of grass afford of nvitritive matter 4.2 dr.] 
 The produce of the space, ditto 56.1 dr. 
 
 At the time the seed is ripe tlie produce is 
 
 Grass, 31 oz. The produce per acre 
 80 dr. of grass weigh when dry - 32 dr. ') 
 
 The produce of the space, ditto ' 198. 1|. 5 
 The weight lost by the produce of one acre in 
 
 drying 
 
 64 dr. of grass afford of nutritive matter 3.2 dr. ') 
 The produce of the space, ditto 27. OA 5 
 
 The weight of nutritive matter which is lost by leaving the crop 
 
 t')] the seed be ri])e, being nearly one-half of its value - 1238 
 
 64 ih, of the roots afford of nutritive matter 5.2 dr. 
 
 Tlie proportional value which the grass, at the time the seed is ripe, bears to 
 that at the time of flowering, is as 14 to 18. 
 
 The above details prove this grass to have merits, which, if compared with 
 those of other species, rank it with some of the best grasses. The small loss 
 of weight wJiich it sustains in drying might be expected from the nature of 
 the substance of the grass ; and the loss of weight at each period is equal. 
 The grass alfords the greatest quantity of nutritive matter when in flower, 
 which makes it rank as one of those best adapted for hay. 
 
 12659 10 
 18461 15 = 1153 13 15 
 
 15 
 
 LXVII. Poa fertilis. Var. B. Host. G. A. The species. 
 
 Fertile meadow g-rass. \'ariety 1. Nat. of Gei-many. 
 
 At the time of flowering, the produce from a brown sandy loam, is 
 
 34 dr. 
 1561 
 
 Grass, 23 oz. The produce per acre 
 
 80 dr. of grass weigli when dry 
 
 The produce of the space, ditto ■^•"-'■s 
 
 The weight lost by the produce of one acre in 
 
 drying .,..--- 
 
 64 dr. of grass afford of nutritive matter 3 dr. ^ 
 The produce of the space, ditto - 17.1 dr. S 
 
 At the time the seed is ripe, the produce is 
 
 250470 
 106448 
 
 or lbs. per aci-e 
 =15654 6 
 
 = 6653 8 
 
 9000 14 
 11740 12 = 733 12 12 
 
 lr.$ 
 
 239580 
 131769 
 
 44973 
 = 8235 
 
 18717 
 
 6738 
 1169 
 
 Grass, 22 oz. The produce per acre 
 
 80 (/r. of grass weigh when dry - 44 dr. 
 
 The produce of the soace, ditto 193.2 <// 
 
 The weight lost by the produce of one acre in 
 drying ...--.- 
 
 64 dr. of grass afford of nutritive matter 5dr 
 
 The produce of tl>e space, ditto 27.2 dr 
 
 The weight of nutritive matter which is lost by taking the crop 
 
 at tlie time of flowering, exceeding one-third part of its value is 436 1 3 
 Tlie proportional value which the gra.ss, at the time of flowering, bears to 
 
 that at the time the seed is ripe, is as 12 to 20. 
 
 The i-Toduce of latter-math is 
 
 Grass, 7 oz. The produce per acre - - 76230 = 4764 6 
 
 64 </r. of grass afford of nutritive matter 1.2 dr. J 786 10 = 111 10 10 
 
APPENDIX. 285 
 
 The proportional value which the g^rass of the latter-math bears to that at 
 the time of ilowering, is as 6 to 12, and to that at the time the seed is ripe, as 
 6 to 2U. 
 
 LXVIII. Cynomnis ernciefurmis. Beckmannia erucasformis. Host. G. A. 3, 
 t. 6. ■ 
 
 Linear spiked dog's-tail grass, ^at. of Germany. 
 
 At the time the seed is ripe the produce is 
 
 oz. or //w. per acre 
 
 Grass, 18 oz. The produce per acre - - 196020 =12261 4 
 80 f/r. of grass wcisfh when dry - 36 dr. ') ooor.n n ' eei'^ i a 
 ine produce of the space, ditto 129. -y 3 
 
 The weight lost by the produce of one acre in 
 
 dryii.g 6738 3 
 
 64 (/r. of grass afford of nutri'ive matter* 3.1 «''■• "/ qc;^ 9 _ r99 9 9 
 The produce ofthe space, ditto 14.2| 5 " ~ 
 
 LXIX. PMeiim nodosum. W. B. 2, P. 118. 
 
 Bulbous stalked cat's-tail grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a clayey loam, is 
 
 oz . or lbs. per acre 
 
 Grass, 18 or. The produce per acre - - 196020 0=12251 4 
 
 80 c/r. of -grass weigh when dry - 38rf'-? 'jqiq < « 
 
 The produce of the space, ditto 136| 5 ^^ 8 = 5819 5 S 
 The weight lost by the produce of one acre in 
 
 drjing . 6431 14 8 
 
 64 f/r. of grass afford of nutritive matter 2.2 f/r.^ yA^r n _ 4~« Q n 
 
 The produce of the space, ditto ll.lJr.5 4^0 ^ u 
 
 This grass is inferior in many respects to the Phleum pratense. It is sparing- 
 ly found in meadows. From the number of bulbs which grow out ofthe straws, 
 a greater portion of nutritive matter might have been expected. This seems 
 to prove, that these bulbs do not form so valuable a part of t'.e plant as the joints,, 
 wliicli are so conspicuous in the Phlevm pratense, the nutritive powers of whicb 
 exceed those of the P. nodosum, as 8 to 28. 
 
 LXX. Pldeum pratense. Wither. 2. P. 117. 
 
 Meadow cat's tail grass Nat. of Britain, 
 
 At the time of flowering, the produce from a clayey loam. Is 
 
 Grass, 60 or. The produce per acre 
 80 dr. of grass weigh when dry - 34 dr. ■? 
 
 The produce of the space, ditto - 408 dr. 3 
 
 The vveigiit lost by the produce of one acre in 
 
 drying . - 
 
 64 dr. of grass afford of nutritive matter 2.2 dr. ) 
 Tlie produce ofthe space, ditto 37.2 dr. 5 
 
 The weight of nutritive matter which is lost by leaving the crop 
 
 till the seed be ripe, exceeding one-half of its value - 2073 11 
 
 At the time the seed is ripe the produce is 
 
 Grass, 60 oz. The produce per acre - • 643400 =40837 8 
 
 80 Jr. of grass weigh when dry - 28 dr.-) „,03fi5 10^.07 T? n 
 
 The produce of the space, ditto ^:'b dr.S 0=19^97 13 
 The weight lost by the produce of one acre in 
 
 drying . - 21439 11 e 
 
 oz. 
 653400 
 
 or lbs. per acre 
 =40837 8 
 
 277695 
 
 = 17355 15 
 
 . 
 
 23481 9 
 
 25523 7 
 
 = 1595 3 
 
286 
 
 APPENDIX. 
 
 oz. or lbs. per acre 
 
 64 Jr of ffrass afford of nutritive matter 5.3 dr ') ^—..^ ,j „^,a ,^ ,^ 
 Th£ produce of the space, ditto . 86.1 dr.^ ^^'^"^ ^* == 3b68 15 14 
 
 The produce of latter math is 
 
 Grass, 14 oz The produce per acre - - 152460 = 95^28 12 
 64 (/r. of grass afford of nutritive matter 2 dr 4764 6 = 297 12 6 
 
 64 dr: of the straws affoid of nutritive matttrr 7 dr. The nutritive powers of 
 the straws slm]3ly, therefore, exceed those of tiie leaves, in proportion as 28 
 to 8 ; and the grass at the rime of flower. ng-. to t..at at the time the seed is 
 ripe, as lU to 23 ; and the latter math to tlie grass of the flowering crop, us 8 
 to 10. . 
 
 The comparative merits of this grass will appear, from the above particulars, 
 to bd very great; to which may be added the aiitindance of tine foliage tha' it 
 produces early in the spring. In this respect it is inferior to the Fou JevtHis, 
 and Poa ang^isitfoHa only. The value of tlie straws at the time the seed is 
 ripe, exceeds that of the grass at the time of flowering, as 28 to 10 ; a circnm- 
 stance v/hich increases its value above many others; for, by this projx'rt} , its 
 valuable early foliage may be cropped, to an ad\anced period of the season, 
 without injury to the crop of hay, which, in other grasses which send I'orth 
 their flowering straws early in the season, would cause a loss of nearly one-half 
 of the value of the crop, as is clearly proved by former examples ; and -his 
 property of the straws, makes the plant peculiarly valuable for the purpose 
 of hay. 
 
 LXXI. PMeum pratense. Var, minor. Wither. B. 2, 118. Var. 1. 
 Meadow cat's-tail grass. Var. Smaller. Nat. of Britain. 
 
 At the time of ripening the seed, the produce from a clayey loam, is 
 
 ■\ 
 
 Grass. 40 oz. The produce per acre 
 
 80 dr of grass weigh when dry - 34 dr. 
 
 The produce of the space, ditto 272 dr. 
 
 The weight lost by the produce of one acre in 
 
 drying 
 
 64 dr. of grass afford of nutritive matter 2.3 dr. 
 
 The produce of the space, ditto 272 dr 
 
 The produce of latter-math is, 
 Grass, 14 or. The produce per acre 
 
 64 dr. of grass afford of nutritive matter 1.2 dr. 
 
 oz. 
 
 435600 
 
 or lbs. per acre 
 =27225 
 
 185130 
 
 =11570 10 
 
 
 
 . 
 
 15654 6 
 
 
 
 1817 
 
 3 = 1169 13 
 
 3 
 
 152460 
 3573 
 
 = 9528 12 
 4 = 223 5 
 
 
 4 
 
 LXXII. FAymus arenarivs. Engl. Bot. 1672. 
 
 Upright sea lyme grass. Nat. of Britain 
 
 At the time the seed is ripe, the produce from a clayey loam, is 
 
 Grass, 64 oz. The produce per acre 
 80 dr. of grass weigh when thy • , 45 dr. I 
 
 The produce of the space, ditto • 576 dr. 5 
 
 The weight lost by the produce of one acre in 
 
 drying 
 
 64 dr. of grass afford of nutritive matter 5 
 
 The produce of the space, ditto - 80 
 
 696960 
 392040 
 
 dr.1 
 dr.S 
 
 54450 
 
 or /6s. per acre 
 =43560 
 
 =24502 8 
 
 18957 
 = 3403 
 
 LXXIII. Elymus geniculatus. Pendulous 13'me grass. Engl. Bot. 15S6. 
 Pendulous sea lyme grass. Nat. of England, 
 
APPENDIX. 
 
 287 
 
 At tlie time of flowering, the produce from a sandy soil, is 
 
 Grass, 30 oz. The produce per acre 
 80 dr of grass weigh when dry - 32 Jr. ^ 
 
 Tlic produce of the space, ditto 192 dr. 3 
 
 I'he weight lost by the produce of one acre in 
 dryuig 
 
 oz. or lbs. per acre 
 
 326r00 =20418 12 
 
 I0O68O = 8167 8 
 
 64 df. of grass afford of nutritive matter 3.1 dr.\ 
 The produce of the sp.ice, ditto 24.1^ 5 
 
 16590 
 
 12251 4 
 = 1036 14 
 
 LXXIV. Bromus inermis. Host. G. A. 1, t. 9. 
 
 Awnless brome gTass. Nat. of Germany, 
 neman in 1794. 
 
 Introduced by Mr. Ilua- 
 
 At the time the seed is ripe, tlie produce from a black sandy soil, is 
 
 t;l 
 
 Grass, 18 oz. The produce per acre 
 80 (//•. of grass weigh when dry 35 dr. 
 
 The produce of the space, ditto 126 c?; 
 
 The weight lost by the produce of one acre in 
 
 drying- 
 
 64 dr. of grass afford of nutritive matter 4 1 dr. '> 
 The produce of the space, ditto l^-'Jy 3 
 
 The produce of latter-math is 
 
 Grass, 13 oz. Tlie produce per acre 
 
 64 dr. of grass afford of nutritive matter 1.1 dr. 
 
 oz. 
 196020 
 
 or lbs. per acre 
 = 12251 4 
 
 85758 12 
 
 == 5359 14 12 
 
 . 
 
 6891 5 4 
 
 13016 15 
 
 = 813 8 15 
 
 141570 
 2765 
 
 = 8848 2 
 = 172 13 
 
 LXXV. .^igrostis vulgaris. Wither. Bot. 2, 132. Hud. A. capllaris. Dr. Smithy 
 A. arenaria. 
 Fme bent grass. Nat. of. Britain. 
 
 At the time the seed is ripe, the produce from a sandy soil, is 
 
 152460 
 76230 
 
 or lbs per acre 
 = 9528 12 
 
 4764 6 
 
 .2^%dr.l 
 
 4019 15 
 
 4764 
 251 
 
 6 
 3 15 
 
 Grass, 14 oz. The produce per acre 
 80 dr. of grass weigh when dry - 40 dr. 
 
 The produce of the space, ditto 112 dr. 
 
 The weight lost by the produce of one acre in 
 
 drying 
 64 dr. of grass afford of nutritive matter 1.2-^ 
 The produce of the space, ditto 5 
 
 This is one of the most common of the bents, likewise the earliest; in these 
 respects, it is superior to all others of the same family, but inferior to seveml 
 of them in produce, and the quantity of nutritive matter it affords. As the 
 species of this f:\mily are generally rejected by the cultivator, on account of the 
 lateness of their flowering ; and this circumstance, as has alreadj' been obser- 
 ved, does not always imply a proportional lateness of foliage, their compara- 
 tive merits in this respect may be better seen, by bringing them into one vieWj 
 as to the value of tiieif early foliage. 
 
 The 
 
 aj>parept difference 
 
 Tlieir nutritive 
 
 
 of time. 
 
 powers. 
 
 Agrostis vulgaris 
 
 Middle of April 
 
 - 1-2^ 
 
 palustris 
 
 One weel;' later 
 
 - 2.3^ 
 
 siolonifera 
 
 Two, ditto 
 
 - 3.2 
 
 canina 
 
 Ditto, ditto 
 
 1.3 
 
 ■itricia 
 
 Ditto, ditto 
 
 ' 1.2 
 
288 APPENDIX. 
 
 The apiiarenl 
 
 ■ difference 
 
 Their nutritive 
 
 (if time. 
 
 
 
 jjoweis. 
 
 nivea Tliree 
 
 weeks, 
 
 ditto 
 
 2 
 
 littoralis Ditto, 
 
 
 ditto 
 
 o 
 
 repcns Ditto, 
 
 
 ditto 
 
 o 
 
 mt'xicana Ditto, 
 
 
 ditto 
 
 2 
 
 fasciculans Ditto, 
 
 
 ditto 
 
 2 
 
 T.XXVI. Agrostis palmtns. Wither. Bot. 2, P. 129. Var. 2, alba. Engl. Bot. 
 1189. A. alba. 
 Marsh bent grass. 
 
 At tlie time of flowering', the produce from a bog-earth, is 
 
 oz. or lbs. per acre 
 
 Grass, 15 or. The produce per acre - - 163350 6 =102u9 6 
 80 f/r. of errass weiHi when dry 36 dr.') ,-.-,, n'r q ,itn.t o o 
 
 The produce ot the space ditto - lOo dr.^ 
 Tlie weight lost by the produce of one acre in 
 
 drying -.....:..- 5615 2 3 
 
 64 Jr of grass afford of nutritive matter 2.3 rfr. > 7018 15 = 4""? 10 15 
 The produce of the space, ditto - 10. H 3 _ a 
 
 At the time the seed is ripe the produce is 
 Grass, 20 oz. The produce per acre - - - 217800 =13612 8 
 80 rfr. of grass weigh when dry 32rf..J ^ = 5445 
 
 The produce 01 the space, ditto 128 dv.$ 
 
 The weight lost by the produce of one acre in 
 
 drying 8167 8 
 
 64 f/?'. of grass afford of nutritive matter 2.j dr.') q"\q q _ '>P4 14. Q 
 
 The produce of the space, ditto 13 3 dr. 5 ^ ~ 
 
 The weight of nutritive matter which is lost by taking the crop at 
 
 tlie time of flowering, being one-fourth part of its value - 146 3 10 
 
 The proportional value of grass, in each crop is equal. 
 
 T.XXVII. Panicum dactijhm. Engl. Bot. 850. Host. G. A. 2, t. IS. 
 Creeping Panic grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a sandy loam, with manure, is 
 
 oz. or lbs. per acre 
 
 fJrass 46 oz. The produce per acre - - 500940 =31308 12 
 
 Hi; dr, of grass weigh when dry 36 dr. ") gor^oa « 
 
 Tlie produce of the space, ditto 33l.0| 5 "^^^^^^^ ^ 
 'I'he weight lost by the produce of one acre in 
 
 drying -• 
 
 64 dr. of grass afford of nutritive matter 2 dr. 7 -i rg^x .5 
 The produce of the space, ditto - 23 dr. $ 
 
 .LXX\'ni. Aqmslis utolonifi'ra. Engl. Bot. 1532. Wither. Bot. 2, 181. (Fiorln, 
 l)r. Richardson.) 
 Creeping bent. Nat. of Britain. 
 
 At the time of flowering, the produce from a bog soil, is 
 
 oz. or lbs. per acre 
 
 Crass, 26 or. The produce per acre - - 283140 =17696 4 
 
 80 Jr. of grass weigh when dry - .35 Jr.") ,^^07- 10 77.10 1 19 
 The produce of the space, ditto - i82,/r.5^ 
 
 '>■'".£ weight lost by the jjroducc of one acre - - - 9732 15 O 
 
 14088 15 
 
 
 
 17219 13 
 
 
 
 97866 6 
 
 
 
APPENDIX. 
 
 289 
 
 <54 dr. of grass afford of nutritive matter 3.2 dr. 
 The produce of the space, ditto 22.3 dr 
 
 :] 
 
 oz. 
 15484 
 
 or lbs. per acre 
 = 967 1.2 3 
 
 36 dr. 
 20I.2| 
 
 504920 
 137214 
 
 =19057 8 
 = 8575 14 
 
 10481 10 
 16675 = 1042 3 
 
 At the time the seed is ripe the produce is 
 
 Grass, 28 oz. The produce per acre 
 
 80 dr. of grass weigh when dry 
 
 I'he ])roduce of the space, ditto 
 
 'I'he weight lost by the produce of one acre in 
 
 drying ....... 
 
 64 dr. of grass afford of nutritive matter 3.2 di 
 The produce of the space, ditto 24.2 dr 
 
 The weight of nutritive matter which is lost by taking the crop at 
 
 the time of flowering, being nearly one-fourteenth of its value, 74 7 3 
 
 I.XXIX. ^groxtis stolonifera. Var. angnstilblia. 
 
 Creeping bent, with narrow leaves. Nat. of Britain. 
 
 At the time the seed is ripe, the produce fnmi a bog soil, is 
 
 Grass, 24 oz. The produce per acre 
 80 dr. i)f grass weigh when dry 36 dr. > 
 
 The produce of the space, ditto 172.3y 5 
 
 The weight lost by the produce of one acre in 
 drying ... . . . . . 
 
 64 dr. of grass afford of nutritive matter 3 dr. ") 
 
 The produce of the space, ditto 18 dr. 5 
 
 I'he weight of nutritive matter afforded by tlie produce of one 
 
 acre of the Agrostis stolonifera, exceeding that of the variety in 
 
 proportion, is 6 to 8 - 276 8 1 
 
 The above details will assist the farmer in deciding on the comparative va- 
 lue of this gi"ass. From a careful examination it will dovibtless appear to pos- 
 .sess merits well worthy of attention, though perhaps not so great as has been 
 supposed, if the natural place of its growth and habits be impartially taken 
 into the account. From the couchant nature of this grass, it is denominated 
 couch-grass, by practical men, and from the length of time that it retains the 
 vital power, after being taken out of the soil, is called squitch, quick, full of 
 life, &c. 
 
 LXXX. Agrostis camia. Engl. Bot. 1856. 
 Brown bent. Nat. of Britain. 
 
 oz. 
 261360 
 
 or lbs. per acre 
 =16335 
 
 117612 
 
 = 7350 12 
 
 . 
 
 8984 4 
 
 12251 
 
 4 = 765 11 4 
 
 At the time of flowering, the produce from a brown sandy loam, is 
 
 \i \ 43013 =- 2688 5 
 
 oz. or /6s. per acre 
 
 98ulG = 6125 10 
 
 
 
 
 3437 
 3828 8 = 239 
 
 Grass, 9 oi. The produce per acre 
 80 dr. of grass weigh when dry 34 dr. 
 
 The produce of the space, ditto - 63-j- . 
 The weight lost by the produce of one acre in 
 
 drying 
 
 '64 dr. of grass afford of nutritive matter 2.2 dr. \ 
 The produce of the space, ditto - 5.21^ 3 
 
 LXXXI. Agrostis canina. Var. muticae. 
 
 Awnless brown bent. Nat. of Britain. 
 
 At the time the seed is ripe, the produce from a sandy soil, is 
 
 oz. or lbs: per acre 
 
 Grass, 21 oz. The produce per acre - ^-- - 
 
 O 
 
 228690 =14293 2 
 
290 
 
 APPENDIX. 
 
 w. 
 
 80 dr. of grass weigh when dry - 24 dr. "> 
 The produce of the space, ditto 100.3-y ^ 
 
 The weight lost by the produce of one acre in 
 
 drying 
 
 64t/r. of grass afford of nutritive matter 1.3 dr. ^ 
 The produce of tlie space, ditto - 9.0j 5 
 The weight of nutritive matter which the produce of one acre of 
 
 the awnless variety, exceeds that of the last mentioned species 151 
 
 68607 
 
 6253 
 
 or lbs. per acre 
 = 4287 15 
 
 10005 3 
 = 390 13 
 
 
 
 
 8 11 
 
 1.XXXII. Agrostis stricta. Curt. A. rubra. 
 
 Upright bent grass. Nat. of Britain. 
 
 At the time the seed is ripe the produce from a bog soil, is 
 Grass, 11 or. The produce per acre - - 119790 = 7486 14 
 80 dr. of grass weigh when dry - 29 dr. "> 43433 ^^ ^ 2713 15 
 
 The produce 01 the space, ditto - oo* dr.y 
 
 The weight lost by the produce of one acre in 
 
 drj'ing - 4772 15 
 
 64 dr. of grass afford of nutritive matter 1.2 dr.\ 0007 o — it*? r 
 The produce of the space, ditto - * '' " ^ "^^^^ ^~ ^'^ ' 
 
 .2 dr.\ 
 
 LXXXni. Agrostis nivea. 
 
 Snowy bent grass. Nat. of Britain. 
 
 At rhe time the seed is ripe, the produce from a sandy soil, is 
 
 Gra-iS, 7 oz. The produce per acre 
 80 ./' . of grass weigh when dry - 22 dr. i 
 The pvoduce of the space, ditto - 30.S-|- 3 
 The weight lost by the produce of one aci'e in 
 
 dryiig - 
 
 64 dr. of grass afford of nutritive matter 2 dr. 7 
 The produce of the space, ditto - o^dr. 3 
 
 76230 
 20963 4 
 
 or lbs. per awe 
 = 4764 6 
 
 1310 3 
 
 3454 3 
 2382 3 == 148 14 
 
 LXXXIV. Agrostis fascicularis. ILids. Var. canina. Curt. 
 Tufted leaved bent. Nat. of Britain. 
 
 At the time of flowering, the produce from a light sandy soil, is 
 
 Grass, 4 oz. The produce per acre 
 
 80 ^r. of grass weigh when dry - 20 dr.') 
 
 The produce of the space, ditto - 16 dr. 5 
 
 The weight lost by the produce of one acre in 
 
 drying 
 
 64 dr. of grass afford of nutritive matter 2 dr. 7 
 
 The produce of the space, ditto - 2 </r. 3 
 
 43560 
 10890 
 
 or lbs. per acre 
 = 2722 8 
 
 = 680 10 
 
 2041 14 
 1361 4 = 85 1 4 
 
 LXXXV 
 
 Festiica pirmatn. Bromus pinnatus. Engl. Bot. 730. 
 Spiked fescue. Nat. of Britain. 
 
 At the time the seed is ripe, the produce from a light sandy soil, with ma- 
 nure, is 
 
 Grass 30 oz. The produce per acre 
 
 80 dr of grass weigh when dry - 32 d> 
 
 The produce of the space, ditto - 192 
 
 dr. I 
 dr.^ 
 
 oz. or lbs. per acre 
 
 326700 —20418 12 
 
 130680 « 8167 8 
 
APPENDIX, 291 
 
 0^, OP lbs. per acre 
 
 4:he weiffht lost by tlie produce of one acre in 
 
 drying - - 12251 4 
 
 64 dr. of grass afford of nutritive matter 1.1 dr.'> g^gn it «. 398 to 13 
 Tlie produce of the space, ditto - 9.1 ^ 5 
 
 LXXXVI. Panicum viride. Curt. Lond. Engl. Bot. 875. 
 Green Panic grass. Nat. of Britain. 
 
 At the time the seed is ripe, the produce from a light sandy soil, is 
 Grass, 8 oz. The produce per acre - - 87120 = 5445 
 
 80 rfr. of grass weigh when dry - 32 dv.} ^^^^^ Q »= 2178 
 The produce or the space, ditto - 51^ 3 
 The weight lost by the produce of one acre in 
 
 drying 326/ ' 
 
 64 Jr. of grass afford of nutritive matter 1.2 dr.") nr, ., ^. iot q i^ 
 
 The produce of the space, ditto - 3 dr. 5 -^^^^ ^^' °° 1-^' ^ ■^* 
 
 LXXXVII. Panicum sanguinale. Curt. Lond. Engl. Bot. 849. 
 Blood coloured panic grass. Nat. of Britain. 
 
 At the time the seed is ripe, the produce from a sandy soil, is 
 
 Grass, 10 oz. The produce per acre - - 108900 0. = 6806 4 
 64 dr, of grass afford nutritive matter ■'^•^■^g- 1914 4 = 119 IQ 4 
 
 This and the prec«dmg species are strictly annual, and from tlie results of 
 this trial their nutritive powers appear to be very inconsiderable. The seed 
 of this species, Mr. Schreber describes (in Beschreibung der Graser) as the 
 manna grass. In Poland, Lithuania, 8tc. it is collected in great abundance when 
 after being thoroughly separated from the husks, it is fit for use. When boil- 
 ed with milk, or wine, it forms an extremely palatable food, and is most com- 
 monly made use of wliole, in the manner of sago, to which it is in general pre. 
 ferred. 
 
 LXXX^^II. Agrostis lobata. Curtis, lobata carenai'ia, 
 Lobed bent grass. 
 
 At the time of flowering, the produce from a sandy soil, is 
 
 0-. or ibs. per acfe 
 
 Grass, 10 oz. The produce per acre - - 108900 = 6806 4 
 80 dr. of grass weigh when dry - - 40 dr. "> 
 
 The produce of the space, ditto - -BOdr.S ^4450 = 3403 2 
 Tlie weight lost by the pi'oduce of one acre in 
 
 drying -".-.-.-... 3403 2 
 
 64 dr. of grass afford of nutritive matter 3 dr.\ ,.,„. ., _ ^ 
 
 The produce of the space, ditto - 7.2dr,S ^^"* ^^ -^ -^^^ ^ 1^ 
 
 LXXXIX. Agrostis repens. Whitlier. Bot. A. nigra. 
 
 Creeping rooted bent, black bent. Nat. of Britain. 
 
 At the time of flowering the produce from u clayey loam, is 
 
 oz. or lbs. per acr^e 
 
 Grass, 9 oz. The produce per acre - - 98010 = 6125 10 
 
 80 dr. of grass weigh when dry - - 35 dr. > Acyom e. o«-q 1 « •; 
 
 The produce ofthe space, ditto - -63 d;. 5 ^^^^ 6=26/9 15 6 
 The weiglit lost by the produce of one acre in 
 
 drying 3445 \Q IQ 
 
 64 rfc. of grass afford of nutritive matter 3 dr. \ >■£■« o 00^ a « 
 
 The produce of the space, ditto - 6.3 dr. $ '*^594 o = 287 3 o 
 
304920 
 
 = 19057 
 
 8 
 
 106722 
 
 = 670 
 
 2 
 
 - 
 
 12387 
 
 6 
 
 9528 12 
 
 595 
 
 8 12 
 
 292 APPENDIX. 
 
 XC. Jgrontis JMexicana. Hort. Kew. 1. P. 150. 
 
 Mexican bent grass. Nat. of S. America. Introduced, 1780, by M. tl 
 Alexander. 
 
 At the time of flowering, the produce from a black sandy soil, is 
 
 oz. or lbs. per acre 
 
 Grass, 28 oz. The produce per acre 
 80 dr. of grass weigli when dry - 28 '^r. ~i 
 
 The produce of the space, ditto - 156.33- 5 
 The weight lost by the produce of one acre in 
 
 drying - 
 
 64 dr. of grass afford of nutritive matter 2 dr. \ 
 The produce of the space, ditto - - 14 c/r 5 
 
 XCI. Stipa pennata. Eng. Bot. 1356. 
 
 - Long-awned feather gi-ass. Nat. of Britain. 
 
 At the time of flowering, the produce from a heath soil is 
 
 or. or lbs. per acre 
 
 Grass, 14 oz. The produce per acre - - 152460 = 9528 12 
 
 80 Jr. of grass weigh when diy - '- 29 f'?'. 1 ,.o/;<; ,« ^aha o io 
 
 The produce of thi space, ditto - 81 } 5 ^^^66 12 = 3454 2 12 
 The weight lost by the produce of one acre in 
 
 drying - . . . . 6074 9 4 
 
 64 f/r. of grass afford of nutritive matter 2.3 dr. 7 .^ ac\q t n 
 
 The produce of the space, ditto - 9.2^ 3 0^51 u — 4uy 7 U 
 
 XCII. Triticiim repens. Engl. Bot. 909. 
 
 Creeping rooted wheat grass. Nat. of Bi'itain. 
 
 At the time of flowering, the produce from a light clayey loam is 
 
 or. or lbs. per acre 
 
 Grass, 18 oz. The produce per acre 
 80 dr. of grass weigh when clry - 32 ''f. ") 
 
 The produce of the space, ditto - 115j- 3 
 The weight lost by the produce of one acre in 
 drying -.--... 
 
 64 dr. of grass afford of nutritive matter 2 dr. \ 
 The produce of the space, ditto - - 9 </r. > 
 64 dr. of the roots, afford of nutritive matter 5.'i dr. The proportional value 
 of the roots, is therefore to that of the grass, as 23 to 8. 
 
 XCin. Mopecunts ngrostis. Engl. Bot. 848. A. myosuroides. 
 Slender fox-tail grass. Nat. of Bi-itain, Curt. Lond. 
 
 At the time of flowering, the produce from a light sandy loam is 
 
 oz. or lbs. per acre 
 
 Grass, 12 oz. The produce per acre - - 130680 = 8167 8 
 
 80 c/r. of grass weigh when dry - - ol *0 "ira ia r 
 
 The produce of the space, ditto - 74.l| 5 ^"^'^^ ^ ~ ""^^^ ^* ^ 
 
 64 Jr. of grass afford of nutritive matter 1.3 Jr. > _,._„ . „„,-, - . 
 
 The produce of the space, ditto - 5.1 Jr. 3 '^^''^ ' '^'^'^ ^ * 
 
 XCIV. Bromus asper. Engl. Bot. 1172. Curt. Lond. Bromus hirsutus. H«ds. 
 Bromus ramosus. B. sylvaticus, volger. B. altissimus. 
 H^ry stalked brome grass. Nat. of Britain. 
 
 196020 
 
 = 12251 4 
 
 78408 
 
 = 4900 8 
 
 - 
 
 . 7350. 12 
 
 6125 10 
 
 = 382 13 10 
 
or. 
 
 
 or lbs. per acre 
 
 217800 
 
 
 
 =,13612 8 
 
 65340 
 
 
 
 =. 4083 12 
 
 - 
 
 
 9528 12 
 
 6806 
 
 4 
 
 = 425 6 4 
 
 871200 =54450 
 416 J:} 283177 8 =17697 
 
 
 9 8 
 
 - 36752 
 -30rt:| ^0418 12 = 1876 
 
 6 6 
 
 2 12 
 
 APPENDIX. - 293 
 
 At the time of flowering the produce from a light sandy soil, is 
 
 Grass, 20 oz. The produce per acre 
 80 dr of grass weigh when dry - - 24 dr. > 
 The produce of the space, ditto - - 96 dr. ^ 
 The weight lost by the produce of one acre in 
 
 drying ..----. 
 
 64 dr. of grass afford of nutritive matter 2 dr. 
 The produce of the space, ditto 10 dr. 
 
 XCV. Phalaris canardensis. Engl. Bot. 1310. 
 Common Canary grass. Nat. of Britain. 
 
 At the time of flowering, the produce from a clayey loam, is 
 
 oz. or lbs. per acre 
 
 Grass, 80 oz. The produce per acre 
 80 dr. of grass weigh when dry 
 The produce of the space, ditto 
 The produce in weight lost by drying 
 64 dr. of grass afford of nutritive matter 
 The produce of the space, ditto 
 
 XCVI. MeUca ccernlea. Curt. Lond. Engl. Bot. 750. 
 Purple Melic grass, Nat. of Britain. 
 
 At the time of flowering, the produce from a light sandy soil, is 
 
 oz or lbs, per acre 
 
 Grass, 11 or. The produce per acre - 119790 = 7486 14 Q 
 
 80 dr. of grass weigh when dry - - 30 dr.') 
 
 The produce of the space, ditto - • 66 dr. 5 ^^^^l 4 -= 2807 9 4 
 The weight lost by the produce of one acre in 
 
 drying 4679 4 3 
 
 64 Jr. of gi'ass afford of nutritive matter 1.2 rf^o 07?/- o 
 
 The produce of the space, ditto ■- 4.0| J ^'^^ " =" I'^S 4 8 
 
 XCVII. Dactylis cynosuroides. Linn. fil. fasci. 1. P. 17. 
 
 American cock's foot grass. Nat. of N. America, 
 
 At the time of flowering, the produce from a clayey loam, is 
 
 oz. or lbs. per acre 
 
 Grass, 102 oz. The produce per acre - ^ 111780 =69423 1 
 
 80 rfr. of errass weiffh when dry - -48 ^ cccAro n a-^^. . 
 
 The produce of thi space, ditto - 979^ ^ ^^6468 =41654 4 
 The weight lost by the produce of one acre in 
 
 drying - - - 27769 8 
 
 64 Jr. of grass afford of nutritive matter 1.3 rfr.l on'^'o n lono a 
 
 The produce of the space, ditto - 44.2| 3 '" u = I6y8 4 
 
 Of the Time in lohich different Grasses produce Flowers and Seeds. 
 
 To decide positively the exact period or season, when a grass always comef; 
 into flower, and perfects its seed, will be found impracticable ; for a variety of 
 circumstances interfere. Each species seems to possess a peculiar life in 
 which various periods may be distinctly marked, according to the varieties of 
 its age, of the seasons, soils, exposure, and mode of culture. 
 
 The following Table, which shews the time of flowering, and the time 
 of ripening the seed of those grasses growing at Woburn, which are meu' 
 tioned in the Experiments, must therefore only be considered as serving for 
 a test of comparison, for the different grasses, growing under the same qircum- 
 stances. 
 
294 
 
 APPENDIX. 
 
 r^ 
 
 Time of flowering. 
 
 Time of ripeitiog the 
 Seed. 
 
 Anthoxant'mim odoratum 
 
 llolcusodoratus - 
 
 Cynosurus caeruleus - 
 
 Alopecurus pratensis 
 
 Alopecurus aipinus 
 
 Poa alpina 
 
 Poa pratensis 
 
 Poa cserulea 
 
 Avena pubescens 
 
 Festuca hordiformis 
 
 Poa trivialis - 
 
 Festuca g-lauca 
 
 Festuca glabra 
 
 Festuca rubra • 
 
 Festuca ovina 
 
 Briza Media 
 
 Dactylus glomerata 
 
 Bromus tectorum 
 
 Festuca oambrica 
 
 Bromus diandrus - 
 
 Poa angustifblia 
 
 Avena elatior 
 
 Poa elatior 
 
 Festuca duriuscula 
 
 Milium etl'usum 
 
 Festuca pratensis 
 
 Lolium perenne 
 
 Cynosurus cristatus 
 
 Avena pratensis 
 
 Bromus multiflorus 
 
 Festuca loliacea 
 
 Poa cristata 
 
 Festuca myurus 
 
 Aira flexuosa 
 
 Hordeum bulbosum - 
 
 Festuca calamaria 
 
 Bromus littoreus 
 Festuca elatior 
 Nardus stricta 
 Triticum, (species of) 
 Festuca fluitans 
 Festuca dumctorum 
 Holcus lanatus 
 Poa fertilis 
 Arundo colorata 
 Poa (species of) - 
 Cynosurus erucseforniis 
 Plileum nodosum 
 Phleuni protcnse 
 Elymus arenarius 
 Elyinus geniculatus 
 Trifolium pratense 
 Trifolium pratense «^ 
 Trifoliiim niacrorhi/.UTP 
 Sanguisorba canadensis 
 Bunias oricntalis - 
 Medicago sativa 
 Hedysaruni onobrychis 
 
 20 
 30 
 
 April 29 
 
 April 29- 
 
 April 30 
 
 May 20 
 
 May 
 
 May 
 
 May 30 
 
 ftlay 30 
 
 June 13 
 
 June 13 
 
 June 13 
 
 June 13 
 
 June 16 
 
 June 20 
 
 June 24 
 
 June 24 
 
 June 24 
 
 June 24 
 
 June 28 
 
 June 28 
 
 June 28 
 
 June 28 
 
 June 28 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 Julv 
 
 July- 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 July 
 
 Jii]v 
 
 June 
 
 21 
 
 June 
 
 25 
 
 June 
 
 20 
 
 June 
 
 24 
 
 June 
 
 24 
 
 June 
 
 30 
 
 July 
 
 14 
 
 July 
 
 14 
 
 July 
 
 8 
 
 July 
 
 10 
 
 July 
 
 10 
 
 July 
 
 10 
 
 July 
 
 10 
 
 July 
 
 10 
 
 July 
 
 10 
 
 July 
 
 10 
 
 July 
 
 14 
 
 July 
 
 16 
 
 July 
 
 16 
 
 July 
 
 16 
 
 July 
 
 16 
 
 July 
 
 16 
 
 July 
 
 16 
 
 July 
 
 20 
 
 July 
 
 20 
 
 July 
 
 20 
 
 July 
 
 20 
 
 July 
 
 28 
 
 July 
 
 20 
 
 July 
 
 28 
 
 July 
 
 28 
 
 July 
 
 28 
 
 July 
 
 28 
 
 July 
 
 28 
 
 July 
 
 28 
 
 July 
 
 28 
 
 Aug. 
 
 6 
 
 Aug. 
 
 6 
 
 Aug. 
 
 b 
 
 Aug. 
 
 10 
 
 Aug. 
 
 12 
 
 July 
 
 20 
 
 July 
 
 26 
 
 July 
 
 28 
 
 July 
 
 28 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 July 
 
 30 
 
 Aug 
 
 6 
 
 Aug. 
 
APPENDIX. 
 
 295 
 
 Hordeum pratense 
 Poa compressa 
 Poa aqiiatica - 
 Rromus cristatus - 
 Elymus sibiricus 
 Aira csespitosa 
 Avena flavescens 
 Bromus sterilis 
 Holcus mollis - . 
 
 Bromus inermis - 
 Aijrostis vulgaris 
 Agrostis palustris 
 Panicum dactylon 
 Agrostis stolonifera 
 Agrostis stolonifera (var.) 
 Agrostis canica 
 Agrostis stricta 
 Festuca pennata 
 Panicum viride 
 Panicum sanguinale - 
 Agrostis lobata 
 Agrostis repens 
 Agrostis fascicularis 
 Agrostis nivea - 
 Triticum repens - 
 Alopecurus agrestis 
 Bromus asper 
 Agrostis mexicana 
 Stipa pennata - 
 Melica caerulea 
 Phalaris cananiensis 
 Dactylus cynosuroidcs' 
 
 Time of flowerinp. 
 
 July 20 
 July 20 
 Julv 20 
 July 24 
 July '24 
 July 24 
 Julv 24 
 July 24 
 July 24 
 July 24 
 July 24 
 July 28 
 July 28 
 July 28 
 July 28 
 July 28 
 July 28 
 July 28 
 Aug. 2 
 Aug. 6 
 Aug. 6 
 Aug. 8 
 Aug. 10 
 Aug. 10 
 Aug. 10 
 Aug 10 
 Aug. 10 
 Aug. 15 
 Aug. 15 
 Aug. 20 
 Aug. .30 
 Aug. 30 
 
 Time of ripeniiifr the 
 
 Seed 
 
 
 Aug. 
 
 8 
 
 Aug. 
 
 8 
 
 Aug. 
 
 8 
 
 Aug. 
 
 10 
 
 Aug. 
 
 10 
 
 Aug. 
 
 10 
 
 Aug 
 
 15 
 
 Aug. 
 
 20 
 
 Aug. 
 
 20 
 
 Aug. 
 
 20 
 
 Aug. 
 
 •20 
 
 Aug. 
 
 28 
 
 Aug. 
 
 28 
 
 Aug. 
 
 28 
 
 Aug. 
 
 28 
 
 Aug. 
 
 28 
 
 Aug. 
 
 30 
 
 Aug. 
 
 30 
 
 Aug. 
 
 15 
 
 Aug. 
 
 20 
 
 Aug. 
 
 20 
 
 Aug. 
 
 25 
 
 Aug. 
 
 30 
 
 Aug. 
 
 30 
 
 Aug. 
 
 30 
 
 Sept 
 
 8 
 
 Sept 
 
 10 
 
 Sept 
 
 25 
 
 Sept 
 
 25 
 
 Sept 
 
 30 
 
 Sepi 
 
 30 
 
 Oct. 
 
 20 
 
 * In the experiments made on the quantity of nutritive matter in the 
 grasses, cut at the time the seed was ripe, the seeds were always separa- 
 ted ; and the calculations for nutritive matter, as is evident from the de- 
 tails, made for grass and not hay. 
 
 Of the different Soils referred to in the Appendix. 
 
 Iv books on agriculture and gardening much uncertainty and confusion 
 arises from the want of regular definitions of the various soils, to distinguish, 
 them specifically by the names generally used : thus the term bog-earth, is 
 almost constantly confounded with peat-moss, and heath-soil ; also the term 
 • light loam,' * heavy soil,' &c. are given, without distinguishing whether that 
 be ' light' from sand, or this • heavy' from clay In minute experiments, it is 
 doubtless of consequence to be as explicit as possible in those particulars. 
 The following short descriptions of such soils as are mentioned in the details 
 of the experiment are here given for the above purpose. 
 
 1st. By ' loam' is meant any of the earths combined with decayed animail, 
 or vegetable mattter. 
 
 2nd. ' Clayey-loam,' when the greatest proportion is clay. 
 
 ord. ' Sandy-loam' when the greatest proportion is sand. 
 
 4th. 'Brown-loam' when the greatest proportion consists of decayed vege- 
 *able matter. 
 
 5th, ' Rich-black loam,' when sand, clay, animal and veg'ctable matters are 
 
296 APPENDIX. 
 
 combined in unequal proportions, the clay greatly divided, being in the least 
 proportion, and the sand and vegetable matter in the greatest. 
 
 The terms ' light sandy soil,' ' light brown loam,' ^c. are varieties of the 
 above, as expressed. 
 
 Observations on the chemical Compositions of the nutritive ^fatter afforded by the 
 Grasses in their different States. By t/ie Editor. 
 
 X HAVE made experiments on most of the soluble products supposed to con- 
 tain the nutritive matter of the grasses, obtained by Mr. Sinclair ; and 1 have 
 analysed a few of them. Minute details on this subject would bt- little inter- 
 esting to tlie agriculturist, and would occupy a considerable space ; 1 shall 
 therefore content myself with mentioning some particular facts, and some ge- 
 neral conclusions, which may tend to elucidate the inquiry respecting the fit- 
 ness of the different grasses for permanent pasture, or for alternation, as grecu 
 crops with grain. 
 
 The only substances which I have detected in the soluble matters procured 
 from the grasses, are mucilage, sugar, bitter extract, a substance analogous to 
 albumen, and diflferent saline matters. Some of the products from the after- 
 math crops gave feeble indications of the tanning principle. 
 
 The order in which these are nutritive has been mentioned in the First 
 Lecture ; the albumen, sugar, and mucilage, probably wlien cattle feed on 
 grass or hay, are for the most part retained in the body of the animal ; and the 
 bitter principle, extract, saline maiter, and tunnin, when any exist, probably 
 for the most part voided in the excrement, with the woody fibi-e. The ex- 
 tractive matter obtained by boiling the fresh dung of cows, is extremely similar 
 in chemical characters to that existing in the soluble products from the grasses. 
 And some extract, obtained by Mr. Sinclair, from the dung of sheep and of 
 deer, which had been feeding upon the Lolium perenne, Dactylis glomerata, 
 and Trifolium repens, had quahties so analogous to those of the extractive 
 matters obtained from the leaves of the grasses, that they might be mistaken 
 for each other. The extract of the dung, after being kept for some weeks, had 
 still the odour of hay. Suspecting that some undigested grass might have re- 
 mained in the dung, which might have furnished mucilage anc' sugar, as well 
 as bitter extract, 1 examined the soluble matter very carefully for these sub- 
 stances. It did not yield an atom of sugar, and scarcely a sensible quantity of 
 mucilage. 
 
 Mr. Sinclair, in comparing the quantities of soluble matter afforded by the 
 mixed leaves of the Lolium perenne, Dactylis glomerata, and Trifolium repens, 
 and that obtained from the dung of cattle fed upon them, found their relative 
 proportions as 50 to 13 
 
 It appears probable from these facts, that the bitter extract, though soluble 
 in a large quantity of water, is very little nutritive ; but probably it serves the 
 purpose of preventing, to a certain extent, the fermentation of the other ve- 
 getable matters, or in modifying or assisting the function of digestion, and may 
 thus be of considerable use in forming a constituent part of the food of cattle. 
 A small quantity of bitter extract and saline matter is probably all that is need- 
 ed, and beyond this quantity the soluble matters must be more nutritive in 
 proportion as they contain more albumen, ^ugar, and mucilage, and less nutri- 
 tive in proportion as they contain other substances. 
 
 In comparing the composition of the soluble products afforded by different 
 crops from the same grass, I found, in all the trials I made, the largest quanti- 
 ty of truly nutritive matter, in the crop cut when the seed was ripe, and least 
 bitter extract and saline matter ; most extract and saline matter in the autumn- 
 al crop ; and most saccharine matter, in proportion to the other ingredients, in 
 the crop cut at tlie time of flowering. I shall give one instance : 
 
 100 parts of the soluble matter obtained from the Dactylis glomerata, cut in 
 Sower, afforded. 
 
 Of sugar . . . - - 18 parts 
 Of mucilage - ... 67 
 
APPENDIX. 
 
 29T 
 
 Of coloured extract, and saline matters, 
 with some matter rendered insoluble 
 by evaporation - - . 15 
 
 100 parts of the soluble matter from the seed crop, afforded, 
 
 Sugar ..... 9 parts 
 
 Mucilage ..... 8.5 
 Extract, insoluble, and saline matter 6 
 
 100 parts of soluble matter from the after math crop, give, 
 
 Of sugar . . - . . 11 parts 
 
 Of mucilage - - - - 59 
 Of extract, insoluble, and saline mat- 
 ters. 30 
 
 The greater proportion of leaves in the spring, and particularly in the late 
 autumnal crop, accounts for the difference in the quantity of extract ; and thp 
 inferiority of the comparative quantity of sugar in the summer crop, probably 
 depends upon the agency of light, which tends always in plants to convert sac^ 
 charine matter into mucilage or^ starch. 
 
 Amongst the soluble matters afforded by the different grasses, that of the 
 Elymus arenarius was remarkable for the quantity of saccharine matter it con- 
 tained, amounting to more than one-third of its weight. The soluble matters 
 .'S'om the different species of Festuca, in general afforded more bitter extractive 
 matter than those from the different species of Poa. The nutritive matter from 
 tlie seed crop of the Poa compressa was almost pure mucilage The soluble 
 matter of the seed crop of Phleum pratense, or meadow cat's tail, afforded 
 more sugar than any of the Poa or Festuca species. 
 
 The. soluble parts of the seed crop of the Holcus mollis and Holcus lanatus, 
 contained no bitter extract, and consisted entirely of mucilage and sugar. 
 Those of the Holcus odoratus afforded bitter extract, and a peculiar substance 
 having an acrid taste, more soluble in alcohol than in water. All the soluble 
 extracts of those grasses that are most liked by cattle, have either a saline or 
 subacid taste ; that of the Holcus lanatus is similar in taste to gum arabic. Pro- 
 bably the Holcus lanatus, which is so common a grass in meadows, iittght bft 
 madt palatable to cattle by being sprinkled over with salt. 
 
 I have found no differences in the nutritive produce of the crops of the dif- 
 ferent grasses cut at the same season, which would render it possible to esta. 
 blish a scale of their nutritive powers ; but probably the soluble matters of the 
 after-math crop are alway,s from one-sixth to one-third less nutritive than those 
 from the flower or seed crop. In the after math the extractive and saline mat- 
 ters are certainly usually in excess ; but the after-math hay mixed with sum-- 
 mer hay, particularly that in which the fox-tail and soft grasses are a^iundant, 
 would produce an excellent food. \ 
 
 Of the clovers, the soluble matter from the Dutch clover contains mbst muci- 
 lage, and most matter analogous to albumen : all the clovers contain more bittei- 
 extract and saline matter than the common proper grasses. When ptiit-e clover 
 is to be mixed as fodder, it should be >.vith siimmc" hav, rath'^rthan alter-nrafh 
 
 51? 
 
ait ID ]s So 
 
 • 
 
 Page. 
 
 Acids, account of those found in vegetables 76 
 
 Age of trees, by what limited --.-.-- 17^ 
 
 Alcohol, theory of its formation ........ 94 
 
 Alburnum, uses of - - - 46, 173 
 
 Alkalies, method of ascertaining their presence in plants - - 79 
 
 effects produced by, in vegetation ..... 20 
 
 Animal substances, their composition, &c 188 
 
 ■ ________^ decomposition of -...,. 187 
 
 Atmosphere, nature and constitution of - - - - - . I43 
 
 Animal matter, mode of ascertaining its existence in soils - . 118 
 
 Bark, its oiRce and uses 44j 166 
 
 Barks, their relative value for tanning skin ..... 65 
 
 Blight in Corn, its cause 181 
 
 Bread, its manufacture, theory of its production - - . . 98 
 
 Burning, its use in improving soils - 233 
 
 Canker in trees, probable mode of curing - - . . . J80 
 
 Carbonic acid, a part of the atmosphere ...... 145 
 
 necessary to vegetation ...... ^^2 
 
 Cements, on those obtained from limestone 221 
 
 Chemistry, its application to agriculture - 9 
 
 ' importance in agricultural pursuits - - . . gS 
 
 Combustibles, simple, referred to- 36 
 
 Combustion, supporters of, mentioned 35 
 
 Courses of crops, particular ones recommended .... 242 
 
 Corn, its tillering, theory of this operation . - - - _ I6I 
 
 Diseases of Plants, their causes discussed ..... igQ 
 
 Earths, on those found in plants 81 
 
 Electricity, its influence on vegetation - - - . . . 33 
 
 Elements chemical, of bodies 34 
 
 ■ — '■ — laws of their combinations .... 40 
 
 Excrements, use of as manures - 201 
 
 Fairy rings, their causes - -. 243 
 
 Fallowing, theory of 22, 239 
 
 Fermentation, phaenomena of- 94 
 
 Fly-turnip, plan for destroying or preventing 152 
 
 Flowers, their parts and office - 51 
 
 Geology, referred to as teaching the nature of rocks • - - 134 
 
 Crafting, gencK^ views on this process - 173 
 
800 INDEX. 
 
 Pag^ 
 Grasses, on those iit tor pasture - - - - - - 244 
 
 Gravitation, its effects on plants 27 
 
 Green crops recommended - - - -- - - - 242 
 
 Gypsum, its use as a manure 224 
 
 Heat, its effects on vegetables ' - - 32, 125 
 
 Husbandi-y diill, its advantages ....-,. 241 
 
 Ice, its anti-pulrcscent powers ....... 190 
 
 trrigation, theory of its effects 238 
 
 Irritability, vegetable, its existence doubted - - ■ - - - 168 
 
 Land, causes of its fertility 139 
 
 '■ ^ ban-eiincss --.-.... 141 
 
 Leaves, tiieir functions .--•-..... 45 
 
 Light, its effect on vegetation 153 
 
 tiimestone, its nature and uses ---.--. 20, 215 
 
 _ action in the soil - 21 
 
 ■' mode of burning 223 
 
 •— ■ magnesian, its jjeculifer properties ... - 22, 219 
 
 Lime, mode of ascertaining the quantity, in limestones and soils - 116 
 salts of, on the mode of detecting them in soils ... 120 
 
 Manures, on their applications --*..... 184 
 
 how taken into the vegetable system .... 185 
 
 fei'mentation of-------- 10, 205 
 
 in what state to be used •■ 207 
 
 animal .......... 201 
 
 ~ mineral 218 
 
 ■ > vegetable -.-.-.--.. 191 
 
 saline 199, 213 
 
 jSIalting, theory of the process of ---*--- - 149 
 
 Matter, powers of discussed --...--. 27 
 
 Metals, account of -... 37 
 
 Metallic oxides, those found in plants ..--.. 81 
 
 Mildew, cause of -------.. . 181 
 
 Meat, method of preserving it ....... jgo ^ 
 
 Oils, fixed, their nature and production ...... 72 
 
 Oxygene, its presence in the atmosphere, and uses . . « I47 
 
 . necessary to gerjniuation ..... 147^ igQ 
 
 Faring and burning, theory of their operation - - - - . 234 
 
 Pasture, where advantageous ........ 244 
 
 Plants, organization of 43, 98 
 
 Plants, parasitical, described as the cause of disease in corn - . 181 
 
 Peat mosses, on tlieir formation - 132 
 
 on tiieir improvement ....._ 142 
 
 Putrefaction, methods of jjreventing ... . . . . 190 
 
 Pith nature of ---.---.-. . 47 
 
 Plants, parts of - 43 
 
 Quicklime, injurious to soils ...._... 216 
 
 Rocks, their number and arrangement ...... 134 
 
 those from which soils are derived, or on which they rest - 137 
 
 Sap, cause of its ascent discussed - -164 
 
 course of ^ 13, 162 
 
 -•"— - its composition discussed -- 104 
 
i:nD£:^» 
 
 301 
 
 Pagft 
 
 ^alte, thtir uses as manure ^"9, 21S 
 
 — — on such as are found in vegetables ... - - ol 
 
 on tliose found in soils, account of - - - • ■ " ^^^ 
 
 Seeds, on those produced by crossing ^' " 
 
 germination of 148 
 
 their nature and uses -» ^-^ 
 
 Simple substances desci'ibed ..-.---- 36 
 
 Sods, properties of -- ^"^f ^}'f 
 
 composition of .-.----- Hlj 1~^> 
 
 — — method of analysing 11* 
 
 formation of ------**"* I'' ^ 
 
 their constituent parts 1^^ 
 
 improvement of -- 1^1 
 
 — — their classification ..------- lo-' 
 
 Subsoils, varieties of, and their effects ..---- 130 
 
 Soot, pi'operties of as a manure .--.--- 209 
 
 Sugar, mode of refining .-- - 59 
 
 Tanning principle, its application to taiming 64 
 
 ■ 1 quantity in different baij^ ..... 65 
 
 artificial -•■ 67 
 
 Temperature of soils discussed 125 
 
 Trees, habits of, discussed ...-.--. 178 
 
 ■ M . cause of their decay _-.----. 173 
 
 . age of 174 
 
 tJrine, its use as a manure 200 
 
 ■\'^egetables, their chemical composition S5 
 
 — — improvement of, by cultivation 176 
 
 •' renovation of the atmosptiere ..... 158 
 
 . the causes of their growth discussed .... 171 
 
 Vegetable matter, mode of ascertaining its quantity in soils - - 118 
 
 — — — its analysis -- 85 
 
 — — — — decomposition of, described - - - - 1 87 
 
 — principles, their arrangement in plants ■ . - - - 98 
 
 • life, phaenomena of discussed - . . . . - 171 
 
 - - matter, decomposition of -. 186 
 
 Vegetation, influenced by gravitation 27 
 
 influence of light in 161 
 
 progress of 152, 227 
 
 its effect on a soil 242 
 
 Veins or mines, their situations 136 
 
 Water, absorption of by soils -- 127 
 
 its state in the atmosphere 143 
 
 Wheat, transplantation of .....-<.- 16j. 
 
 crossing of--------e- 177 
 
 Wines, theory of their formation 93 
 
 ■ ■ quantity of spirits they contain -.-... 5g 
 
IXIiEX TO TKE APP¥iKl>lX- 
 
 Pag-e 
 
 ^^I'rosiis canina, brown bent ----»--- 289 
 
 canina var. vmtica, awnless brown bent - - - - 289 
 
 ■ fascicularis, tufted-leaved bent .-.--- 290 
 — — — lobata, lobed bent grass ---_-.-- 291 
 — — ^— mexicana, mexican bent grass - - - - ' - - 292 
 — — nivea, snowy bent gi'ass .-.-_-. 289 
 
 ' palustris, March bent grass ------ 288 
 
 repens, creeping rooted bent ____-- 291 
 
 ■ stricta, upriglit bent grass -.--.-. 290 
 — — — stolonifera, fiorin creeping bent ------ 288 
 
 ■ stolonifera var. angustifolia, creeping bent narrow leaves - 289 
 
 " vulgaris, fine bent grass --__.-- 287 
 
 Aira aguatica, water hair grass .-_---- 281 
 
 cxspitosa, turfy hair grass --___-- 282 
 
 jlexuosa, waved mountain hair grass - - - - - 37*4 
 
 Alopeciirus agrostis, slender fox-tail grass _ - - - - 292 
 
 alpint^, alpine fox-tail grass ------ 26O 
 
 pratensis, meadow fox-tail grass ----- 259 
 
 Anthoxaiithum odoratum, sweet scented vernal grass _ - _ 258 
 
 Arundo colorata, striped-leaved reed grass - - - - - 278 
 
 Avena elatior, tall oat grass ----____ 269 
 
 - flavescens, yellow oat grass ------- 283 
 
 pratensis, meadow oat grass --__--_ 273 
 
 pubescens, dc^wny oat grass .-_---- 26O 
 
 Briza media, quaking grass ----»-__ 266 
 
 Bromus aspei^ .--.--_--_ 299 
 
 ' cristatus ---------- 282 
 
 diundrus - - -.- - . - - - _ 268 
 
 erecuis, upright perennial brome grass . - - - 270 
 
 inerniis, awnless brome grass ------ 287 
 
 littoreiis, sea-side brome grass ------ 275 
 
 muhiflonis, many-flowering brome grass - - - - 273 
 
 ■ ■ •- tectorum, nodding pannicled brome grass - - - - 267 
 
 sterilis, barren brome grass -..--_ 283 
 
 Bunias orientaUs - - --.--___ <^'7Q 
 
 Cynosurus cieruleus, blue moor grass ---,-__ 259 
 
 cristatus, crested dog's-tail grass . . - . _ 272 
 
 enicaformis, linear spiked dog's-tail grass - - - 285 
 
 Dactylis cymsuroides, American cock's-foot grass ... - 293 
 glomerata, round-headed cock's-foot grass - - . - 266 
 
 Elymus armnrixis, upright sea lyme grass ----- 28G 
 
 geniculatus, pendulous sea lyme grass .... 286 
 
 —— — sibericds, Siberian lyme grass "^ ■• - . - 389 
 
304 INDEX. 
 
 ifage 
 
 Festuca cahvnaria, reed-like fescue grass -•-... 275 
 
 camhrica ....--...-^ 267 
 
 (.uriuscula, hard fescue grass .---.. 269 
 
 dumetonim, pubescent fescue grass ..... 278 
 
 elatior, tUll fescue grass - - 276 
 
 fliiitans, floating fescue grass ...... 277 
 
 glabra, smooth fescue grass ...... 264 
 
 glmica, glaucous fescue grass - 263 
 
 hordiformis, barley-like fescue grass ..... 262 
 
 — — — loUacea, spiked fescue grass ...... 273 
 
 inyurus, wall fescue grass - - - - - - ' - 274 
 
 "^— — ovina, sheep's fescue grass - - - ... . - 265 
 
 pemiata, spiked fescue grass ...-,.. 290 
 
 pratensis, meadow fescue grass - - - - > . 271 
 
 — — — rjibra, purple fescue grass - 265 
 
 Hedysarwn onobri/chis, sainfoin - - . - - .- . 280 
 
 Hordeuin bidbnsum, bulbous barley grass -.--.. 275 
 
 — — — murinum, wall barley grass - , - - - - . - 282 
 
 ■ pratense, meadow barley grass . - . ... 281 
 
 Holcus lanatns, meadow soft grass ....... 277 
 
 • ■■ mollis, creeping soft grass . - - . - . . 283 
 
 odoratns, sweet scented soft grass ...... 258 
 
 Lolium peremie, perennial rye grass ....... 271 
 
 Jifedicago sativa, lucerne - .. . . . . . . 5S0 
 
 J^elica aerulea, purple malic grass -...-.. 293 
 
 Jyfiliu7n effusuvi, common millet grass ...... 270 
 
 JVarJjw striata, upright mat grass --..-.. 27r 
 
 JPanicum dactylum, creeping panic grass ...... 288 
 
 ' ■ ■- sangidnale, blood coloured panic grass - -• . . 291 
 
 viride, green panic grass -_..... 291 
 
 Phalaris canaviensis, common canai'y grass ..... 293 
 Phlenm nodosum, bvilbous- stalked cat's- tail g^-ass .... 285 
 pratense, meadow cat's-tail grass ...... 285 
 
 • var. miliar, meadow cat's-tail grass, van smaller - 285 
 
 Poa alpina, alpine lueadow grass ....... 260 
 
 (ingusiifolia, narrow-meadow grass - - - • . - - 268 
 
 aquatica, reed meadow grass - 281 
 
 ctendea, v. p. pratense, short bluish meadow grass ... 262 
 
 cnmpressa, flat-stalked meadow grass 281 
 
 cristnta, crested meadow grass ....... 274 
 
 elatior, tall meadow grass ........ 269 
 
 fertihs, fertile meadow grass ....... 278 
 
 • var. b. fertile meadow gn^ss, var. 1. .... 284 
 
 marifima, sea meadow grass ....... 272 
 
 /)!'ato;47,9, smooth-stalked meadow grass ..... 261 
 
 ♦ ?riTva/j,s, roughish meadow grass . . - . - . 262 
 
 Potirinm sauguisorba, burnet ........ 279 
 
 Slipn pennata, long armed feather grass ...... 29i 
 
 TrIfoHum r.ncrorhiznm, long-rooted clover ..... 279 
 
 pratense, broad-leaved cultivated clover .... 278 
 
 repens, white clover --...... 279 
 
 Tritiaim repens, creeping rooted wheat grass 29^ 
 
 ^^ sp. wheat ^yvass - 277 
 
TUlEiATl^¥i 
 
 ON 
 
 AS 
 
 FOUNDED ON ACTUAL EXPERIENCE:, 
 
 AND 
 
 AS COMBINED WITH THE LEADING PRINCIPLES 
 
 OB 
 IN WHICH THt 
 
 THEORY AND DOCTRINES OF SIR HUMPHRY DAVY, 
 
 AND OTHER AGRICULTXJEAL CHEMISTS, 
 
 AKE RENDERED FAMILIAR TO THE EXPERIENCED lARMER- 
 
 BY A PRACTICAL AGRICULTURIST. 
 
 PHILADELPHIA: 
 
 I'UBIISUED BY B. WARNEIl, 171, HIKH STKA'KJ . 
 
 182^^1 
 
IPIBISI^ii'lPISc 
 
 IflEORY would always coincide with practice, if 
 the speculator could hold to the mind's eye a complete 
 model of the subject discussed ; could see all the parts 
 in action together, as a machine is surveyed ; and mea» 
 sure excitements and obstructions precisely as they ope- 
 rate. But, in treating of arts which depend for their 
 success on natural operations, the most difficult part of 
 the task is, to assign the proper degree of influence to 
 the many causes and qualities which act invisibly, and 
 cannot be controlled by man. Hence, the philosopher 
 who exercises the strongest intellect on previous systems 
 of Jigriculture, and on the knowledge accumulating 
 from the progress of practical experience and scientific 
 discovery^ cannot be certain that some latent interme- 
 diate impulse in tl\e machine of vegetation, has not elu- 
 ded bis anxious inquiry, or that he is aware of all the 
 causes which exist, and of their conducing to a general 
 effect. 
 
 Amidst these difficulties, the Theorist cannot advance 
 any considerable way beyond the track of experience^ 
 in the pursuit of materials for a new system, without be- 
 ing liable to move on a line which subsequent experience 
 may be compelled to abandon- Meanwhile, an in- 
 dependent and equally specious hypothesis may uphold 
 the reasonableness 'of some branch of established prac- 
 tice impeached by the new system, and vindicate from 
 
IV I'UEFACE. 
 
 the name of prejudice that slow and circumspect transi- 
 tion from tried courses to alleged improvements, which 
 prevents a whole country from being involved in the 
 speculations and risks of an experimental farm. 
 
 The views of Sir Humphry Davy in regard to Soils 
 and Manures may, on many fundamental points, be re- 
 ceived without dispute, as no less sound and practical 
 than they are original and ingenious : but he has advan- 
 ced some new doctrines, and become the advocate of 
 some recent partial practices, which do not accord with 
 the general experience of Gardeners and Agriculturists. 
 Nevertheless, by the connection with the subtile princi- 
 ples and problems of Chemistry under which these are 
 given, the Practical Farmer who may feel dissatisfied 
 with a particular part of the professor's theory, because 
 it is at variance with his own maxims derived from ex- 
 perience, is perplexed and silenced by the reasoning, 
 being unable to enter with perspicuity into the grounds 
 of argument drawn from the depths of philosophy : 
 thus he is asliamed to question a train of deductions by 
 "which he is conducted to a doctrine in which he does 
 not confide. But when theory is opposed to theory, 
 the practical man is disembarrassed, and raised to the 
 situation of an arbiter. 
 
 It may be added, that some few points among the 
 difliiculties of Chemistry, treated by Sir Humphry Davy 
 as fundamental principles, are not yet considered as es- 
 tablished by all the great Chemists; consequently, the 
 speculative deductions from these must stand over for 
 approval, until the assumed principle be exploded or 
 confirmed. 
 
PREFACE. V 
 
 In the following Treatise, the leading doctrines of 
 this illustrious Contributor to the formation of an en- 
 lightened system of Agriculture are brought under re- 
 view; in order that such as are obviously well founded^ 
 or tenable against superficial objections, may be recom- 
 mended to general practice ; as well by corroborating 
 facts and observations, as by the connected order and 
 simplified form in which they are presented ; — and that 
 such as are open to considerable objection, either on prac- 
 tical grounds, or by collision with a contrary hypothe- 
 sis, may be exhibited at the tribunal of reason, and sub- 
 jected to the test of experience, in so plain a shape as 
 shall bring them within the grasp of the Practical Ag- 
 riculturist who may have formed no previous acquaint- 
 ance with Chemical Science. 
 
^m^§, 
 
 PAOIi 
 
 Use op the Sort -- 9 
 
 On the Basis of Soils 10 
 
 Terms for Soils Defined ..-.---• 11 
 On the Improvement of Soils : 
 
 I. Jiy the Admixture of Earths, to improve the Texture of tlie Soil - 13 
 
 Teats of Sniln - 15 
 
 CoiTectiven of ill-conntiliitcd Soils .- 
 
 1. Iron in its Acid Combinations ..... 22 
 
 2. Fixcess of pure Calcareous Matter - ... - 22 
 
 3. Excess of Carbonate of Lime .----- 23 
 
 4. Redundant Sand 23 
 
 5. Excess of Vegetable Matter ...--- 23 
 
 6. liedundancy of Clay -- 23 
 
 n. By Druininff ------.--- 23 
 
 III. By Vanng and Bxirni'ng ...... 24 
 
 IV. By Turmng-in Green Crops us Manure ... - - 25 
 V. By Fallo-wintf .....---. 26 
 
 VI. By Irrigation ......... 35 
 
 VII. By applying Earths as Manures : 
 
 1. I.ime as a Solvent (Quick-lime) 42 
 
 2. Mild Lime - ■ 43 
 
 Time of laying on Lime .--•.. 46 
 
 3. Magnesia -- - 47 
 
 4. I'liospliate of Lime 47 
 
 5. Gypsum ..-. 47 
 
 6. Burnt Clay 54 
 
 Considered as the Food of Plants - - - . 38, 39 
 
 VIII. By introducing Mineral or Saline Substancest as Manures : 
 
 1. Common Salt --.------ 57 
 
 2. Comparative Elfect of different Salts .... 57 
 
 IX. By Manuring -with Refusp. Substances not excrementitiom : 
 
 1. Street and RoaflDirt, and the Sweepings of Houses - 58 
 
 2. Soot 58 
 
 3. fJoal ashes 58 
 
 4. Coal-water -...----- 59 
 
 5. Wood-ashes 59 
 
 6. Carbonate of Ammonia - 59 
 
 7. Coal-tar - - - 59 
 
 8. Rones 59 
 
 9. Horn 59 
 
 10. Hair, Feathers, and Woollen Rags 59 
 
 11. Refuse of Skin and Leather ..-.-. 60 
 
 12. Bleacher'8 Waste .--.-■- 60 
 
Vm CONTENTS, 
 
 Pagb 
 
 13. Soaper's Waste, 60 
 
 14. Fluids of dissolved Animal Substances - - . - 60 
 
 Rlood 60 
 
 Sugar-baker's Scum 60 
 
 Graves 61 
 
 Oily Substances — Train Oil and Blubber ... 61 
 
 Oil-cake 62 
 
 15. Refuse Fish 62 
 
 16 Carrion -- - -•- - - - . . 62 
 
 17. Rape-seed Cake 63 
 
 18. Malt Dust 63 
 
 19. Sea weed 63 
 
 20. Dry Straw, and Spoiled Hay .-...- 63 
 
 21. Vegetable Mould -.--.-.- 64 
 •22. Woody Fibre : ........ 64 
 
 Tanner's Spent Bark ....... 6^1 
 
 Inert Peaty Matter - 64 
 
 Shavings of Wood and Saw.dust 65 
 
 The Fibre and Grain of Wood ..... 65 
 
 23, Ashes of Vegetables not Woody ..... 65 
 
 Burnt Straw 65 
 
 Peat-ashes 65 
 
 X. By Excremcntitiorts Substances applied as J\Ianure : 
 
 1. Dung of Sea-birds 66 
 
 2. Night-soil 66 
 
 3. Pigeon's Dung ........ 67 
 
 4. Tlie Dung of Domestic Fowls ..... 67 
 
 5. Rabbit's-Dung 68 
 
 6. The Dimg of Cattle 68 
 
 7. Hog-dung 70 
 
 8. Urine 70 
 
 JManagement of J\Iamire From the Homestead : 
 
 Professor DaA7's Theory of Composite Manure - - . 71 
 
 Objection noticed by the Professor . - . . . 72 
 
 His own Practical Application of the above Theory • - 72 
 
 Free Remarks on the Theory, and on its Practical Application 72 
 
 Recapitulation 83 
 
 Additional Notes, gee. -.--••- , 85 
 
TREATISE 
 
 ON 
 
 ^Olli^ AXU MAX^IVE^. 
 
 USE OF THE SOIL. 
 
 OORRECT views of the office of the soil disclose the ration- 
 ale of approved modes of tillage ; if one mode is found supe- 
 rior to another, they lay open the cause of it ; and proceeding 
 from courses which are experienced to l)e beneficial, a principle 
 is thus obtained for extending their application. 
 
 One great use of the soil, is to afford a bed for the plant, 
 and a cover for its roots from the sun and from the wind ; while 
 the roots, by taking hold of the ground, act as stays and supports 
 for the trunk of the plant. A second important office is that 
 both of a depository and a channel of nutriment : In these rela- 
 tions, the soil ought to contain a certain proportion of common 
 vegetable basis, and of peculiar substances found in plants on 
 analysis ; it ought again to be easily permeable to air ; also po- 
 rous, for the percolation of water and passage of fluid manures ; 
 well fitted for allowing a plant| by the fine tubes within its-roots, 
 to derive sustenance slowly and gradually from the dissolved 
 and soluble substances mixed with the earths. 
 
 As the systems of roots, branches, and leaves, are very dif- 
 ferent in different vegetables, so specific plants have a preference 
 for peculiar soils in which they flourish most. The plants that 
 have bulbous roots require a looser and lighter soil than such as 
 have fibrous roots : and those of the latter, which have short 
 and slender fibrous radicles, demand a firmei soil than such as 
 have tap roots or extensive lateral roots. Hence, when succes- 
 sive crops of the same plant have drawn out from a soil the pe- 
 culiar properties most adapted to its individual nature, the bed 
 of earth becomes less fit for the same plant, until it has been 
 rested and recruited : while it may be fitter for some other plant 
 of a different constitution than it originally was ; though ex- 
 hausted in regard to the crop which it has long l)orne, it may be 
 fresh for a new sort of vegetable. In short, the principles laid 
 down in the " Practical Gardener," (Introduction to the Knv 
 CHEN Garden, under the head Rotation of Crops^ are more or 
 fess applicable to all the branches of Gardening and Agriculture. 
 
 B 
 
10 
 
 BASIS 01' SOILS. 
 
 Sir Humphrey Davy, an illustrious ornamant of the English 
 school of Chiiinistry, is not more distinguished by his discoveries 
 in philosophy, than by seeking, with true ambition, to make pro- 
 found knowledge subservient to the common arts by which the 
 common wants of mankind are supplied ; he has contributed 
 largely to the service of agriculture, by publishing his scientific 
 researches into the composition of earths, and the true food of 
 plants. With the object of founding a course of agricultural 
 improvement on fixed principles, he has communicated, in the 
 Elements of Agricultural Chemistry/'^ some very important re- 
 sults from a systematic train of experiments. We propose to 
 lay before the Reader the substance of his leading conclusions, 
 divested, as much as possible, of chemical terms ; and to re- 
 view the peculiarities of his system with candour and indepen- 
 dence ; concentrating, for unity of method, scattered articles 
 belonging to the same branch of rural economy. 
 
 In the extensive field of his inquiry, he touches on the prin- 
 ciples of many other arts ; it therefore becomes necessary, in 
 sketching an outline after him, which shall embrace only the 
 department of agriculture, to connect the extracts by details and 
 observations for which Sir H. Davy is not responsible. 
 
 " Soils, in all cases, consist of, either a mixture of finely di- 
 vided earthy matter,| — or of earthy matters not reduced to pow- 
 der, such as gravel and other stones ; more or less combined 
 with decomposed animal or vegetable substances; saline ingre- 
 dients, also, frequently lodge in a soil ; and the earthy matters 
 are frequently accompanied with the oxides of minerals, parti- 
 cularly the oxide of iron.:!: The earthy matters form the true 
 basis of the soil ; the other parts, whether naturally present, or 
 artificially introduced, operate in the same manner as manures. 
 
 Four Earths generally abound in soils :<^ 1. The. aluminous^ 
 j. e- Clay, including alum ; 2. The siliceous^ i. e, Flint, in va- 
 rious stages of decomposition, including flinty sand; 3. The 
 calcareous^ i. e. Limestone, under various modifications,including 
 marie, chalk, and chalky sand ; 4. The magnesian^ i. e. Magne- 
 sia, a stone sometimes mistaken for commonlimestone, but when 
 burnt and applied to land it is much longer in passing from 
 a caustic to a mild state, and under most circumstances is 
 highly pernicious to vegetation. 'llie small proportion in 
 
 • This work, which will be frequently referred to. Is entitled, Elanents of 
 ^gricnltiiral Cliemistry, in a Cowsf of Lfcturcs for the Board of ^igricultitre. 
 By Sir Humphry Davy, LL.D. F.H.S. &c. &.c. 8vo. American, 1820. 
 
 t Ibid. p. 15. , 
 
 t Ibid. pp. Ill, 123. 
 
 § Ibid. p. 15. 
 
TERMS FOR SOILS. 11 
 
 which it may be sometimes bentficial, will be afterwards ex- 
 plained. 
 
 The above are the only earths which have been hitherto found 
 in plants. 
 
 Other primitive earths sometimes enter into soils by the pul- 
 verization of rocky materials. 
 
 TERMS FOR SOILS DEFINED. 
 
 The popular terms for soils are seldom applied with precision. 
 What one man c;(lls a marie, another will call a clay ; and so on. 
 But if a general circulation and acceptance could be obtamed 
 for the principles of definition judiciously laid down by Profes- 
 sor Davy — according to which a soil is to be styled a clay, sand,, 
 or chalk ; a marie, loam or peat ; or a compound of these — the 
 characteristic terms would be every where intelligible. 
 
 In framing a system of definitions, a soil is to take a particular 
 denominationfrom a particular kind of earth, not exactly in pro- 
 portion as that earth may preponderate, or not, over others in form- 
 ing the basis of the soil, but rather in proportion to the influence 
 which a particular kind of earth, forming part of the staple, has 
 on tillage and vegetation. Thus, as clay is a substance of which 
 a comparative small quantity will give a cold and stubborn cha- 
 racter to a soil, the name claifey is often properly bestowed, 
 where the quantity of pure clay to be collected from a given 
 piece of land, is but as 8 to 42, compared with the quantity of 
 sand which another field may contain, and yet barely deserve 
 the denomination of sajidi). 
 
 "The term clayey should not be given to a soil which con- 
 tains less than one-sixth of aluminous matter ;" because less 
 than that will not be attended with the common effects which 
 govern the culture, and limit the crops, for a clayey sod. 
 
 The epithet sandy is not an appropriate distinction for any 
 soil that does not contain at least seven-eight parts of sand ; and 
 sandy soils are to be distinguished into .siliceous sandy or flinty 
 sand, and calcareous sandy or chalky sand. 
 
 The word calcareous, or any denomination implying the 
 presence of mild lime or chalk, is not properly applied unless a 
 specimen of the soil is found stronglv to effervesce with acids, 
 or unless water having a channel in the soil affords a white 
 earthy deposit when boiled. 
 
 A marle consists of mild lime with a small proportion of 
 clay, and sometimes of peat, with a mixture of marine sand 
 and animal remains ; the lime having originated, for the m.ost 
 part, from the decomposition of sea-shells. 
 
 A soil maybe treated as maonesian, where but a small 
 
12 . IMPROVEMENT OF SOILS. 
 
 comparative quantity of magnesian stone is present ; as will be 
 explained in treating of Magnesia as a manure. 
 
 Hie combination of animal or vegetable matter in an inferior 
 proportion with earthy matter, but not lower than one-sixth, 
 makes a loam : the word loam should be limited to soils con- 
 taining at least one-third of impalpable earthy matter (distin- 
 guishable by the touch from sand, chalk, or clay,) combined 
 with decayed animal or vegetable substances not exceeding half 
 the weight of the mere earth; the earthy matters may compre- , 
 hend aluminous, siliceous, or calcareous ingredients, and in 
 some cases be mixed with mineral oxides: according to the pro- 
 portions of which, the soil may be red loam, brown loam, ot 
 black loam ; and in regard to the basis, a clayey loam, a sandy, 
 or a chalky loam. 
 
 A superior proportion of vegetable matter, that is to say, an 
 excess of this above half the bulk of the earthy basis, makes a 
 PEAT. To bring this kind of soil into successful cultivation, 
 the quantity of vegetable matter must, in most cases, either be 
 reduced or counterbalanced by the admixture of some of the 
 simple earths. 
 
 Where a slight tincture of any particular mineral substance 
 has a strong effect on vegetation, this quality should be indica- 
 ted by a corresponding word prefixed to the principal name for 
 the soil. Thus the presence of either salts of iron, or sulphate 
 of iron, ought to be marked by prefixing the term ferruginous 
 to the denomination taken from the basis, to remind the culti- 
 vator that the effect on vegetation will be pernicious, unless he 
 has recourse to an effective remedy. If on the contrary, oxide 
 of iron be found in the soil, there is seldom any occasion to no- 
 tice it in the name: in small quantities, it forms a useful part 
 of soils, and has been found to constitute from a 15th to a 10th 
 part of several highly fertile fields : it is found in the ashes of 
 plants. To persons unacquainted with chemistry it may be use- 
 ful to add, that salt of iron exhibits the crystals obtained from 
 iron by the action of an acid fluid. Sulphate of iron is Cop- 
 peras, a native kind of which is produced in some soils by the 
 effect of the springs and earths on each other. Black oxide of 
 iron is the substance that flies off from red-hot iron when ,it is 
 hammered. Iron appears to be only hurtful to vegetation in 
 Its acid combinations. See Tests of Soils. 
 
 IMPROVEMENT OF SOILS. 
 
 Almost all the expedients 'for improving, enriching, or cor 
 recting a soil, known to agriculturists, may be comprehended 
 under one of the following heads : 
 
IMPROVEMENT OP SOILS. 13 
 
 1 . The admixture of Earths to improve the Texture of the 
 
 Soil. 
 
 2. Draining. 
 
 3. Paring and burning. 
 
 4. Turning in Green Crops as Manure. 
 
 5. Fallowing. 
 
 6. Irrigation. 
 
 7. Applying Earths as Manures. 
 
 8. Introducing Mineral or Saline Elements as Manures. 
 
 9. Manuring with Refuse Substances not excrementitious; 
 10. Manuring with Excrementitious Substances. 
 
 I. By the Admixture of Earths^ to improve the Texture of the 
 
 Soil. 
 
 This is a distinct thing from applying Earths as a manure. 
 It is of avail in proportion as the smallness of the tract, or the 
 value of the plant, to be cultivated, allows the free introduction 
 of new earths, until the staple of the land is composed as desired. 
 Almost all sterile soils are capable of being thus improved ; and 
 sometimes the latent pernicious quality which destroys the va- 
 lue of an extensive tract of land, can be corrected without much 
 expense. 
 
 The best constitution of a soil, is that in which the earthy 
 materials are properly balanced, so as to combine as many ad- 
 vantages of different ingredients as are compatable, and so as 
 to obviate the defects attending any single kind of earth. 
 
 The ground, or basis of the soil, should be well adapted for 
 the admission of air, and for the percolation of moisture, with- 
 out retaining it in winter. 
 
 A well-tempered aptness in the soil to absorb water frofn air, 
 and to retain it in a latent form, is clearly connected with fer- 
 tility. The power to absorb water by attraction, and to hold 
 moisture without being wet, depends on the mechanical struc- 
 ture of the particles of earth, and the balancing effect of diffe- 
 rent earth. Thus sand will attract moisture, but will not keep 
 it lonjr under the influence of heat. Clay will long retain wa- 
 ter which has fallen upon it, and always keep moist under a hu- 
 mid atmosphere : but in continued dry weather, with summer 
 heats, the surface of it, being baked into an almost impenetrable 
 crust, is little capable of absorbing moisture. Hence crude 
 clays form equally bad lands in extremely wet or extremely dry 
 seasons. Chalk is of a middle nature, in this respect. It re- 
 sults, that the soils best adapted for supplying the plant witli 
 moisture by atmospheric exhaustion are compositions*' of ?an(l 
 
 * Elements of AgricuUurul ('hemistry, p. 141. 
 
14 IMPROVEMENT OF SOILS. 
 
 fmel}^ divided clay, and pulverized chalk, with a proportion of 
 animal or vegetable matter.* 
 
 There is besides, in particular earths, an agency subservient 
 to vegetation, which depends on chemical affinities, in those 
 earths, for elementary substances floating in the air, or de]}osited 
 in the soil. Thus, both pure clay and carbonate of lime have 
 an attraction for volatile oils and solutions of oil and sapona- 
 ceous matters, and for much of the pulpy stuff fust disengaged 
 from organic remains. Hence a limited pifoportion of these 
 earths contributes to form a rich and generoufi soil ; because they 
 long preserve in their pores the prepared nourishment of vege- 
 tables, parting with it gradually as it is drawn by growing plants,- 
 and refusing it to the fainter action of air or water. 
 
 The properties of a soil may be aggravated or tempered by 
 the nature of the Subsoil. When the upper layer rests upon 
 a bed of stone, or of flinty gravel, it is much sooner rendered 
 dry by evaporation ; an efl^ect which is beneficial, or otherwise, 
 as the climate is moist in excess, or inclined to aridity. A clayey 
 foundation counteracts the readiness of flinty sand to part with 
 moisture to a drier climate ; so does a bed of chalk in a less 
 degree. 
 
 A soil is neither fit for tillage nor pasture, if it consist en- 
 tirely of impalpable matters,! or of pure clay, pure silica, or 
 pure chalk. Sand may abound in a higher proportion than the 
 more tenaceous earths, without causing absolute barrenness. 
 Thus a tolerable crop of turnips has lieen raised on a soil of 
 which eleven parts in twelve were sand. A good turnip soil 
 from Holkham was found to contain f parts of siliceous sand. 
 If the quantity of impalpable earth and finely divided organic 
 matter l)e a little increased beyond what a sand plant requires, 
 it will suffice for good returns of barley. Although wheat de- 
 pends more on a rich staple, happilj' the constituents of land fit 
 for it are combined with very great diversity. An excellent 
 wheat soil, from Middlesex, afforded ^ of sand ; the rest was 
 chalk, silica, and clay, pretty equally distributed, with a propor- 
 tion of organic matter so surprisingly small (only 22 parts in 
 500) that it may be apprehended some considerable substance, 
 convertible into food for a growing plant, might be included in 
 the chalk. Chalk may in the next degree form the prepondera- 
 ting earth of good soil. A large portion of England is chalk ; 
 
 * The compound of carlli, which seems every where most fiivonrable to 
 ve.G^etation, is that which consists of one-third of chalk, half of sand, and a 
 fifth of clay : from a Paper on the Chemical .^Inali/fiis of Soils, translated from 
 the Italian of Tahbroni, hy Arthur Young-, lisq. (^Jhinals of .^s'l'icullitir, vol. 
 viii. 173.)— " A fifth of clay :" this proportion is too larj^e ; independent of 
 consumable or cropping manure ; by which the clay should be reduced to one- 
 sixth or lower. 
 
 •J Elements of Agricultural Chemistry, p. Ij."!, 
 
TESTS OF SOILS. i5 
 
 and many of the districts where it is the staiile earth, liberally 
 repiiy cultivation.*" 
 
 The Warp-land ^^ alluvial soil) in the East Riding of York- 
 shire, is a strong clayey loam, the fertility of which can hardly 
 be equalled. The sediment gradually adding to the depth of 
 this warp-land, being brought from the higher country by the 
 numerous rivers and streams which open into this common es- 
 tuary, is composed of a variety of substances. Decomposed 
 vegetable and animal matter should be from one-ei^g-hth to a 
 fourth of the bulk of the earthy substances, according to the 
 dependence of the expected crop on the nutritive power of the 
 soil. 
 
 Many soils (observes Sir H. Davy) are in popular language 
 distinguished as cold ; and the distinction, though at first view 
 it may appear to be founded on prejudice, is as just on philoso- 
 phical principles as it is consonant to the experience of the 
 farmer. Some soils are constituted for imbibing a much 
 greater degree of heat from the rays of the sun ; and of soils, 
 brought to the same degree of heat, some cool much faster 
 than others. Soils that consist chiefly of a Stipf white clay, 
 take heat slowly ; and being usually very moist, they retain 
 their heat only for a short time. Chalks are similar in be- 
 ing slowly heated : but being drier, they retain heat longer. 
 A Black soil containing much soft vegetable matter, 
 if the site and aspect dispose it to dryness, is most heated 
 by the sun and air : all the coloured soils, especially those 
 containing much carbonaceous matter (charcoal,) or ferru- 
 ginous matter (iron,) are disposed for acquiring a much higher 
 temperature than pale-coloured soils. When soils are per- 
 fectly dry, those that most readily become heated by the solar 
 rays, likewise cool most rapidly. Moisture without fermenta- 
 tion retards the accession of heat, and accelerates its escape. 
 The faculty of absorbing and retaining moisture has been al- 
 ready brought under tiotice. The method of detecting the pre- 
 sence of some ingredient in the soil which the eye cannot per- 
 ceive, and which escapes the touch when a portion of mould is 
 rubl)ed between the fingers, is by having a specimen of the earth 
 of such cubical dimensions as may be thought proper, dug out ; 
 and finding the materials of it by various chemical tests. 
 
 TESTS OF SOILS. 
 For the common purposes of agriculture, the natural consti- 
 
 • Mr. Stricklund states the remarkable fact, that the .c^reat vein of clialk tci'- 
 minates in the East Hiding; of Yorkshire ; and beyond it northward, no chalk 
 is found ill the island. See also a Map Delineatm^ the Strata of Enjlund and 
 Wales, with part cf Scotland, by W. Sinitii, 1815. 
 
16 TESTS OP SOILS. 
 
 tution of a virgin soil, or the state of improvement which 
 land under tillage has acquired from artificial causes, can, in 
 the great majority of cases, be sufficiently determined by 
 taking up portions of earth in different parts of a field, regard- 
 ing the soil as a separate layer from the subsoil, or strata un- 
 disturbed by cultivation ; and examining these by the common 
 lights which persons employed in agriculture have derived from 
 experience. But when the nature of a virgin soil is entirely 
 unknown, no previous trials of its powers having been made ; or 
 when a cultivated field unaccountably baffles the ordinary course 
 of skilful husbandry, while lands constituted apparently like it 
 make good returns under similar treatment; it is proper to 
 have recourse to the aid which modern chemistry offers to 
 agriculture, for a full and accurate knowledge of the grounds 
 on which success may be expected, or the causes of failure ex- 
 plained and rectified. 
 
 The instruments required for the analysis of soils are few, 
 and of small cost : — a pair of scales, large enough to weigh a 
 quarter of a pound of common earth, and so delicately exact as 
 to turn when loaded with a grain ; a set of weights, correspond- 
 ing with the same limits ; a wire sieve, just coarse enough to 
 pass mustard-seed ; a comuion kettle, or small boiler ; an Ar- 
 gand lamp and stand ; two or three Wedgwood crucibles ; eva- 
 porating basins ; a pestle and mortar ; a bone knife ; some fil- 
 ters, made of half a sheet of blotting-paper, folded so as to con- 
 tain a pint of liquid, and greased at the edges. 
 
 The principal tests, or chemical re-agents for separating the 
 constituents of the soil, are : Muriatic acid (spirits of salts ;) 
 sulphuric acid (oil of vitriol ;) pure volatile alkali, dissolved in 
 water ; solution of prussiate of potassa ; solution of potassa 
 (soap ley ;) solution of neutral carbonate of potassa ; succinate 
 of ammonia ; nitrate of ammonia ; solution of carbonate of am- 
 monia ; solution of muriate of ammonia. Dry carbonate of 
 potassa is sometimes wanted in fusing earths. 
 
 The quantity of soil conveniently adapted for a perfect ana- 
 lysis is from 200 to 400 grains. It should be collected in dry 
 weather, and exposed to the atmosphere till it becomes dry to 
 the touch. 
 
 Independently of regular analysis, the specific gravity of a 
 soil assists to indicate the quantity of animal and vegetable mat- 
 ter it contains ; because the atoms of either are lighter than the 
 atoms of cla}', of sand, or of lime. In proportion as a soil is 
 light, it maybe presumed to be rich. Before a soil is analysed, 
 the other physical properties of it should also be examined ; be- 
 cause they denote, in a sensible degree, the sorts of earth in its 
 composition, and serve to guide the order in which the chemi- 
 cal tests are applied. Siliceous soils are generally rough to the 
 touch, and scratch glass, when rubbed upon it ; calcareous soils 
 (besides effervescing with acids, a trial to be afterwards descri- 
 
TESTS OF SOILS. 17 
 
 bed,) when in the shape of sand, do not scratch glass ; and clay^ 
 while it is generally distinguishable by the touch, neither 
 scratches glass nor effervesces with acids ; ferruginous soils are, 
 for the most part, of a red or yellow colour, or rusty-brown. 
 
 1. Measure of Absorbent Power by the Dissipation 
 OF Latent Water. — After soils have been dried by continu- 
 ed exposure to the air, they still contain a considerable propor- 
 tion of water which adheres to the earths, and to the animal and 
 vegetable rudiments, in such obstinate combination, that it can 
 only be driven off by a high degree of heat. To free a spe- 
 cimen of soil from as much of this water as may be, without 
 otherwise affecting its constitution, let it be heated for ten or 
 twelve minutes over an Argand's lamp, till its temperature at- 
 tain 300° of Fahrenheit. If a thermometer t)e not used,* the 
 proper maximum of heat may be measured by keeping a piece 
 of wood in contact with the bottom of the dish : While the co- 
 lour of the wood remains unaltered, the heat is not excessive : 
 as soon as the wood begins to be charred, discontinue the pro- 
 cess. If a higher heat were applied, the vegetable or animal 
 matter would be decomposed, and all the following train of ex- 
 periment be rendered illusory. 
 
 The loss of weight in the soil thus dried should be noted, as 
 Indicating the absorbent power of the S(jil. Supposing the spe- 
 cimen to have previously weighed 400 grains, the loss of fitty 
 (or an eigth part) denotes a soil absorbent and retentive ot wa- 
 ter in the greatest degree : such a soil will generally be found to 
 contain either much vegetable or animal m.atter, or a large pro- 
 portion of aluminous earth, in which two respects this indica- 
 tion is equivocal ; but the tests to follow will decide. When the 
 loss is onlv from a twentieth to a fortieth part of the whole, the 
 soil is but slightly, absorbent, and siliceous earth probably forms 
 the greatest part of it. 
 
 2. Separation of Gross Fragments. — Loose stones, gra- 
 vel, and vegetable fibres, are artfully kept in the specimen im- 
 til after the water is dissipated: for they participate, in different 
 degrees, in that power of alisorbing moisture which affects the 
 fertility of land. After the process of heating, detach these ; 
 by bruising the soil gently in a mortar, and passing it through 
 the sieve. Take separate minutes of the weights of the vegeta- 
 ble fragments, and of the gravel and stones ; distinguishing the 
 nature of the latter. If calcareous, they will effervesce with 
 acids ; if siliceous, the-y will scratch glass ; and if aluminous, 
 
 .they will be easily cut with a knife, and will refuse the tests^of 
 lime and flint. 
 
 3. Separation of the Sand. — The greater numher of soils 
 '.ontain varying proportions of sand more or less granulated. It 
 
 * FJem^nts of Agricultural Chemistry, p. 112. 
 C 
 
18 TESTS OF SOILS. 
 
 is necessary to separate the sand from the impalpable or more 
 finely divided matters; such as clay, loam, marie, vegetable and 
 animal atoms. Uo do this, boil the silted mass in four times its 
 weight of water : when the texture of the soil is broken, and the 
 water cooled, alternately shake the sediment in the vessel, and 
 suffer it to settle ; for in subsiding, the different parts will be 
 distributed in layers. Thus treated, the coarse sand will gene- 
 rally separate in a minute, and the finer in two or three minutes, 
 while the infinitely small earthy, animal, or vegetable matters, 
 will continue in state of mechanical suspension: so that by pour- 
 ing the water from the vessel after three minutes, the sand will 
 be found divided from the other substances. The other sub- 
 stances, with the water containing them, must be deposited in a 
 filter, to be analysed as under 4. Meanwhile the sand is to be 
 examined, and its quantity registered. It is either calcareous 
 or siliceous ; and its nature may mostly be detected as that of 
 stones and gravel, without a minute analysis. If it consist whol- 
 ly of carbonate of lime, it will rapidly dissolve in muriatic acid, 
 with effervescence ; but if it consist partly of this, and partly of 
 siliceous sand, the latter will be found unchanged after the acid 
 dissolving the lime has ceased to effervesce. This residuum 
 must be washed, dried, and heated strongly in a crucible. Its 
 weight is then ascertained by the balance ; and that, deducted 
 from the weight of the whole, indicates the quantity of calcare- 
 ous sand dissolved. 
 
 4. Analysis of the Finkly-divided Matters. — The 
 water passing through the filtre is to be preserved ; for if any 
 saline particles or soluble animal and vegetable elements exist- 
 ed in the soil, it will be, found to contain them. Meanwhile the 
 fine solid matter^eft on the filter must be collected, and dried. 
 This is usually a compound exceedingly multifarious ; it some- 
 times contains all the four primitive earths, as well as animal 
 and vegetable matter. To ascertain the proportions of these 
 with tolerable accuracy, is the most difficult part of the assay. 
 
 I. Test of Lime in a Solid State. — Of muriatic acid 
 take twice the weight of the promiscuous soil ; and dilute the 
 acid with double the measure of water. Let the mixture remain 
 for an hour and a half, stirring it frequently. 
 
 By this time, if any carbonate of lime or of magnesia existed 
 in the soil, they will have been dissolved in the acid ; which 
 sometimes takes up likewise a little oxide of iron, but very 
 seldom any alumina. 
 
 The fluid should be passed through the filter. Then let the 
 solid matter be collected, washed with rain water, dried under 
 a moderate heat, and weighed. The loss denotes the quantity 
 of solid matter taken up. 
 
 II. Test of Ikon. — Add the washings to the solution, which, 
 if not sour to the taste, must be made so by the addition of fresh 
 
TESTS OF SOILS. 19 
 
 acid. The test now to be added to the whole, is some triple so- 
 lution of prussiate of potassa and iron. If a blue precipitate oc- 
 curs, it indicates the presence of oxide of iron ; and more of the 
 triple solution must be dropped in till this effect ceases. In or- 
 der to weigh the precipitate, it must be collected and heated red. 
 The result is oxide of iron, with perhaps a little oxide of man- 
 ganiisum. 
 
 III. Test of Lime suspended in a Fluid : — also of Mag- 
 nesia. — Having taken out all the mineral oxide, next pour into 
 the fluid a solution of neutralized carbonate of potassa, continu- 
 ing to do so until it will effervesce no longer, and- till both the 
 taste and smell of the mixture indicate an excess of alkaline 
 salt. 
 
 The precipitate that falls down is carbonate of lime : it must 
 be collected on the filter, and dried at a heat below that of red- 
 ness. 
 
 The remaining fluid must be boiled for a quarter of an hour; 
 when the magnesia, if any exist, will be thrown down, combined 
 with carbonic acid. To bring it into a state for being weighed, 
 treat it as the carbonate of lime.* 
 
 IV. Test of Alumina incidentally dissolved and pre- 
 cipitated. — If any minute proportion of alumina should have 
 been dissolved by the acid employed in the first test, it will be 
 found with the carbonate of lime in the precipitate obtained by 
 the third. To separate it from the carbonate of lime, boil it for 
 a few minutes with as much soap lye, or solution of caustic so- 
 da, as will cover the solid matter. Soap lye thus applied dis- 
 solves alumina without acting upon carbonate of lime. 
 
 v. Measure of the Matter destructible by Red- 
 IHEAT. — After the finely-divided promiscuous soil has been act- 
 ed upon by muriatic acid, the next step is to ascertain the quan- 
 tity of insoluble animal and vegetable matter which the residu- 
 um contains. 
 
 Set it in a crucible over a common fire ; and let it be ignited 
 till no blackness remains in the mass ; stirring it often with a 
 metallic rod so as to expose new surfaces successively to the air. 
 The loss of weight ultimately caused, shews the quantity of sub- 
 stance destructible by fire and air. 
 
 When the smell emitted during the incineration resembles 
 that of burnt feathers, it is a certain indication either of animal 
 
 • In case the soil be sufficiently calcareous to efTervesce very strongly with 
 acids, ProfeSsoi- Davy gives us a method of measuring the quantity of carbon- 
 ate of lime, by collecting the carbonic gas expelled by the acid in a pneumatic 
 apparatus described verbally in the Lectures, p. 116. This gas is to be either 
 measured or weighed ; and it will bear the proportion of 43 to 100 to the ori- 
 ginal weight of the carbonate of lime. This may be a very simple process to 
 an expert chemist; but it is neither so easy to describe, nor so cheap to practice 
 in occasional experiments, as that above. In an outline like this, for popular 
 use, it is therefore sufficient to notice it. 
 
20 TESTS OF SOILS. 
 
 matter or of some substance analogous to it : on the other hand, 
 a (.opious blue flame unitormly denotes a corresponding propor- 
 tion of vegetable rudiment. It will accelerate the destruction 
 of matter decompcjsable by ignition, to throw gradually upon 
 the heateu mass some nitrate of ammonia, in the proportion of 
 one-fifth to the weight of the residual soil. 
 
 VI. Separation of the Parts indestructible by Heat. 
 — The remaining parts are generally minute atoms of earthy 
 matter, comprehending alumina and silica, combined with oxide 
 of iron, or of manganesum. 
 
 To separate these, boil them in little more than their weight 
 of sulphuric acid, diluted with four times its weight of wa- 
 ter. 
 
 The substance keeping a solid form after this treatment, may 
 be considered as siliceous. Let it be collected on the filter, 
 washed, dried, and wtighed. 
 
 If the residuum contained any oxide of iron, or of mangane- 
 sum, ihey will have been dissolved by the sulphuric acid. To 
 throw down the oxide of iron, add in excess succinate of am- 
 monia. Whrn this has been done, introduce soap lye, to dis- 
 solve the alumina, and to precipitate the oxide of manganesum. 
 Heat the oxides to redness, and then eigh them. 
 
 Should any magnesia and lime have escaped solution by the 
 first test, that of muriatic acid, (which is rarely the case,) they 
 will be found in the sulphuric acid. Their quantities are ascer- 
 tained by a similar process to that above. 
 
 (Course sometimes substituted for "v. and vi." — If 
 very great accuracy be the object, dry carbonate of potassa must 
 be -mploved as the agent ; of which four times the weight of 
 the subject must be put with it into the crucible, and heated red 
 for half an hour. The mass indestructible by heat must then 
 be dissolved in muriatic acid, and the solution evaporated till it 
 is nearly solid. In this state, add to it distilled water, by which 
 the oxide of iron, and all the earths, except silica, will be dis- 
 solved in combination as muriates. The silica, after filtration, 
 must be heated red. The other substances are separated as from 
 the muriatic and sulphuric solutions above. Where the soil to 
 be analysed contains stones of doubtful composition, this pro- 
 cess is well fitted to determine their charactt-r.) 
 
 VII. Evaporation of the Digesting Water. — The wa- 
 ter first used for boiling the earth as under L 3. (and which was 
 directed to be kept for a separate trial) will contain whatever sa- 
 line matter, or soluble vegetable and animal rudiments, existed 
 in the soil. 
 
 This water must be evaporated to dryness at a heat below 
 boiling. 
 
 If the solid matter obtained be brown in colour and inflam- 
 mable, it may be regarded as vegetable extract, unless in com- 
 
tESTS OF SOILS. 21 
 
 bastion it emit a smell like tnat of burnt feathers, which indi- 
 catts animal or uiouminous matter. If any portion be white, 
 crystalline, and not destructible by heat, it may be considered as 
 saline m its properties. The saline matter altogether bears a 
 muiute proportion to the other constituents; and as most of it is 
 generally common salt, the following tests need seldom be re- . 
 sorted to. Salts of potassa are thrown down by a solution of 
 platina. Sulphuric acid combined with any salt is detected in a 
 solution of baryta by a dense white precipitate. Salts of lime 
 assume a cloudy appearance in a solution containing oxalic acid. 
 Salts of magnesia cause a similar cloudiness in a solution of am- 
 monia. Muriatic acid is discovered by forming clouds in a so- 
 lution of nitrate of silver. Salts containing nitric acid sparkle 
 when thrown on burning coals. 
 
 VIII. Process for detecting Sulphate of Lime, and 
 Phosphate of Lime. — Sulphate of Lime (Gypsum) is to be 
 detected by another independent process ; on which is engrafted 
 a method of 'getting at Phosphate of Lime in a separate state. 
 First, put the residuum, with one-third of jts weight of powder- 
 ed charcoal, into a crucible : and heat the mixture red for half 
 an hoar. The mass is afterwards to be boiled in water, (half a 
 pint to 400 grains,) for a quarter of an hour. Filter the whole : 
 expose the collected fluid for some days to the atmosphere ; and 
 so much gypsum as the soil comprised will be gradually depo- 
 sited as a white precipitate. 
 
 Then to separate the Phosphate of Lime from the solid resi- 
 duum, digest upon it muriatic acid more than sufficient to satu- 
 rate the soluble earths. Evaporate the solution, and pour wa- 
 ter upon the remains. The result will dissolve the earthy com- 
 pounds, and leave the phosphate of lime untouched. 
 
 When Sulphate of Lime and Phosphate of Lime have been 
 thus disengaged in a solid form, it is sometimes necessary to de- 
 duct a sum equal to their weight from the amount of the Car- 
 bonate of Lime ; but that is only when the latter has been cal-> 
 culated by the loss sustained in solid matter, part of which en- 
 ters into the new compounds from which the Sulphate and Phos- 
 phate have been recovered. 
 
 IX. Formula for recapitulating the Results. — When 
 the analysis of a soil is finished, add the quantities together ; 
 and if they nearly equal the original portion of soil,* the assay 
 maybe confided in as accurate. 
 
 Four hundred grains of a good siliceous sandy soil from a hop 
 garden near Tunbridge, Kent, gave these results : — 
 
 Grains 
 
 Water of absorption -...19 
 
 Iioose stones and gravel, chiefly flinty -.•..- S3 
 
 Can-ied over, .... - 72 
 • Elements of Agricultural Chemistry, p. 120. 
 
32 CORRECTIVES OF SOIL&. 
 
 Brought forward, . - - . 72 
 
 Undecomposed vegetable fibres 14 
 
 Fine siliceous sand ---- 212 
 
 S.i. /'Carbonate of lime 19 
 
 1 1 1 Carbonate of magnesia --..... 3 
 
 "3 s 1 Matter destructible by heat, chiefly vegetable - - . 15 
 
 :|^s J Silica 21 
 
 ^3*5"% Alumina ..--......13 
 
 •J a J Oxide of iron --........ S 
 
 g 2 m Soluble matter, principally common salt and vegetable extract 3 
 
 •gS* V^Gypsum ..---.-..- 2 
 
 Loss • - 21 
 
 . 400 
 
 X. Popular Application or DEt ached Steps in the Pro- 
 cess. — The assay may be very much simplified, when the inqui- 
 ry is confined to one leading object. Thus, il it be merely wish- 
 ed to know, whether a soil contain already so much lime as to 
 make it inexpedient to bring on lime as a manure, it will be 
 enough to put the specimen into a dish, and to pour upon it a 
 quantity of muriatic acid : indeed when no other experiment is 
 to be grounded on this trial, good white-wine vinegar may be 
 employed. If the soil immersed in acid effervesces strongly, it 
 is sufficiently charged, or perhaps overcharged, with lime. In 
 a similar way, one or two essential questions may be sometimes 
 solved by resorting to any of the other tests, either alone, or two 
 or three connectedly, in a different order from that which has 
 been set down. 
 
 CORIlECTIVliS OF ILL-CONSTITUTED SOILS. 
 
 The following are simple and efficacious correctives of some 
 bad ingredients in soils, or the excess of some good constituent; 
 the presence of which frequently disappoints even the skilful 
 cultivator, when either the true cause is not suspected, or an ap- 
 propriate remedy is not known. 
 
 1. A farmer with a great portion of common skill is often baf- 
 fled by Iron in its acid combinations. If on washing the 
 specimen of a sterile soil, it is found to contain the Salts of 
 IRON, Sulphate of iron, or any Acid matter, it may be 
 ameliorated by a top-dressing of quick lime ; which converts 
 the sulphate of iron (copperas) into a manure. 
 
 2. If there be an Excess of pure calcareous matter 
 (<JHALK OF lime) in a soil, its constitution maybe improved by 
 turning in, in a green state, some of those vegetables which pos- 
 sess the greatest quantity of acid; also by the application of sand 
 or of clay, with a small proportion of oxide of iron (blacksmith's 
 sweepings) not exceeding ^^ part. The same object may be ob- 
 tained by irrigating with any calybeate water (water containing 
 
CORREqTIVES OF SOILS. 23 
 
 iron,) or by the addition of peat containing vitriolic (i. e. sul- 
 phuric) salts ; both which are calculated to turn lime or chalk 
 into gypsum.* See under VIL 5. why gypsum is sometimes 
 beneficial and sometimes not. 
 
 3. When an Excess of carbonate of lime (charcoal uni- 
 ted to lime) requires the quality of the soil to be modified, gyp- 
 sum applied as a manure, also oxide of iron applied as a cor- 
 rective, seems to produce the very best effects. Carbonate of lime 
 is mild lime in cumbination with charcoal absorbed from decay- 
 ed vegetable or animal matter. The diversified effects of lime 
 as a manure are explained under VII. 1. 
 
 4. Soils REDUNDANT IN SAND are benefited by a top dressing 
 of peat or other vegetable matter, or of decayed animal matter, 
 or by a mixture of clay. Also, if the sand be not calcareous, 
 by marie. 
 
 5. An Excess of vegetable matter is to be removed ei- 
 ther by burning, (See III. Paring and Burning^ or by the ap- 
 plication of earthy materials. The fundamental step in the im- 
 provement of peat land, or a bog or marsh, is draining. Soft 
 BLACK peats, after being drained, are often made productive 
 by the mere application of sand or clay, as a top dressing : sand 
 is greatly to be preferred. When peats are acid, or contain 
 FERRUGINOUS SALTS, calcareous matter is absolutely necessary 
 in bringing them into cultivation. When they abound in the 
 ROOTS AND branches OF TREES, the wood must either bc grub- 
 bed up and carried off, or destroyed by burning ; so when the 
 face of peat is incumbered by living plants containing much 
 WOODY FIBRE, and therefore not proper to be ploughed in the 
 ground, the field must be cleared l;y one of thf same methods. f 
 
 6. Where there is a redundancy of clay in a soil, (and if 
 the quantity of clay exceed one-sixth of the general mass, it is 
 desirable to reduce the proportion,) one of the best dressings 
 which can be applied is a mixture of sand and mild lime; the 
 rubbish of mortar containing both these materials, is an excel- 
 lent thing to improve the texture of a clayey soil. Clay appears 
 to receive no improverrvent from lime alone. Sea-sand may he 
 used alone with good effect. It would be also highly beneficial 
 to introduce as much fermented dung or decayed vegetable mat- 
 ter as would entitle the land to the denomination of a loam. 
 
 II. Bij Draining. No perennial crops, and but few annual 
 plants, can be successfully cultivated where the land is exposed 
 to winter floods, or Vv'here the subsoil is rendered wet by under- 
 springs, or by heavy leakage from neighi)ouring pieces of water 
 lying higher and imperfectly banked off. The importance ol 
 
 * Elements of A'^TicultinV, (;lir'tT)istrv, p. 141, 2-5. 
 t Ibid, p- 142. 
 
24 PARING AND BURNING. 
 
 draining peat land has been adverted to under I. 5. Where 
 open drains woujd he unsightly or inconvenient, as in the inte- 
 rior of a domestic garden, or ornamented ground, a paved 
 brick drain is in the end cheaper than a rubble drain, because 
 the latter is liable to be soon choked by the roots ot" trees. 
 
 III. By Paring and Burning. It is obvious, that in all ca- 
 ses the process of Burning must destroy a certain quantity of 
 vegetable matter ; and it must principally be useful where an 
 excess of this matter renders the soil too rank. It must be of 
 eminent service in reducing to charcoal, or wood ashes, a great 
 accumulation of woody fibre already overrunning the field ; for 
 woody fibre is very slowly reduced to the state of vegetable 
 mould, if left to the process of a natural dissolution : nor is it 
 very rapidly reduced by lime or other solvents artificially ap- 
 plied. 
 
 Burning likewise renders clays less coherent ; and in this 
 way greatly improves their texture, and causes them to be more 
 permeable to water,* and consequently, less retentive of it in 
 stagnant masses. Another cause of the unproductiveness of 
 cold clayey adhesfve soils, is, that the seed is coated with mat- 
 ter impenetrable to air.f When clayey or tenacious soils are 
 burnt, their power or tendency to absorb water from the atmos- 
 phere is diminished in the proportion of 7 to 2 ; and they are 
 brought nearer to a state analagous to that of sands ; the parti- 
 cles are less adhesive, and the mass less retentive of moisture. 
 Thus the process of burning, properly applied may convert a 
 matter that was stiff, damp, and in consequence cold, into one 
 powdery, dry, and warm ; altogether more fitly constituted as 
 a bed for vegetable life. The great objection made by specu- 
 lative Chemists to paring and burning is, that the animal and 
 vegetable matter in the soil is diminished : — But where the tex- 
 ture of the earthy ingredients is permanently improved, thert 
 is more than a compensation. To meet the objection still more 
 dii'ectly, where an excess of inert vegetable matter is present, 
 the destruction of a part of it must be beneficial ; and the car- 
 bonaceous matter in the ashes may be more useful to the crop, 
 than the unreduced vegetable fibre, of which it is the remains,^ 
 could have been. 
 
 The most speedy way of bringing under tillage a meadow 
 overrun with rushes is ; first to drain it, and then to pare oft 
 a thick turf and burn it. 
 
 The cases in which burning must incontestably be prejudi- 
 cial, are those of sandy dry flinty soils containing little ani- 
 mal or vegetable matter : here it can only be destructive ; icK 
 
 ' Klements of Agricultural Chemistiy, p. 22. 
 t Ibid. p. 149. 
 t Ibid. p. 234. 
 
TURNING-IN GUEEN CROPS. 2^5 
 
 it decomposes that constituent which is already below the mini- 
 mum proportion, and on the presence of which, in a limued de- 
 • gree, the productiveness of a soil depends.* 
 
 " Burning without fire." A new method has lately been 
 discovered of substituting quick lime for fire ; and experiments 
 made upon it before the Workington Agricultural Society gave 
 general satisfaction. The lime in its most ciustic state, fresh 
 from the kiln, is laid upon the vegetable surface to be consumed ; 
 and before it is weakened by exposure to the air, water, just in 
 sufficient quantity to put it powerfully intp action, is applied. 
 This fierce compound will not only consume the vegetable co- 
 A'ering, but affects the clay, or other upper stratum, as if it had 
 been in contact with fire. It supersedes the trouble which has 
 hitherto attended burning ; and in respect to poor soils which 
 •would be improved by the two distinct operations of burning 
 and liming in the common mode, it bids fair to bring them 
 sooner on a par with those of superior quality. 
 
 IV. By Tiirnhig-in Green Crops as Manure, — This is di- 
 rectly opposed to Burning Turf, in regard to intention and ef- 
 fect I and is particularly serviceable where the basis of vegeta- 
 ble mould is to be augmented, being an extension of the prin- 
 ciple on which Paring Turf without Burning is resorted to. — 
 When Green Crops are turned into the clod, besides enriching 
 the staple with nutritive matter, they promote the fermentation 
 and decomposition of woody fibre buried near the surface ; and 
 which is a useless incumbrance in an undecayed state. 
 
 " When GREEN CROPS are to be employed for enriching a 
 soil, they should be ploughed in, if possible, when in flower, or 
 at the time when the flower is opening ; for in this stage, they 
 contain the largest quantity of soluble matter. Green Crops, 
 pond-weeds, the paring of hedges or ditches, or any kind of 
 fresh vegetable matter not woody, require no preparation! to 
 be fitted for manure. When old pastures are broken up for til- 
 lage, not only is the soil enriched by the death and slow decay 
 of the plants which have previously deposited soluble matters 
 in the clod ; but the leaves and roots of the grasses (vegetating 
 just before the change of culture) afford saccharine, mucilagin- 
 ous, and extractive matters, which become hnviecUutelu the food 
 of tlie crop J also the gradual decomposition of the grasses af- 
 fords a supply of vegetable mould for several years. ^'' 
 
 After giving the substance of Sir H. Davy's theory on any 
 
 specific subject in agriculture, it will not be often necessary to 
 
 ncur the hazard of questioning some incidental deduction from 
 
 ae system; because the principal branches of his theory are so 
 
 )nsonant with experience, that they incontestJbly contribute 
 
 ound and intelligible principles for applying more extcnsivelv, 
 
 • Elements of Agricultuial fihemistw, p, 22. 
 
26 lALLOWlNtJ. 
 
 and with niuie certain eilcct, entire classes of means at the 
 ct)ui.iiand of the culti\'atur, — where the resources to which 
 the practical larmer had arrived, by the empirical course 
 of laying different ingredients on land without knowing ttieir 
 precise operation, were previously few and limited, or their 
 utility doubtful. 
 
 But in regard to the effect of vegetable matters as ma- 
 nures, there is a vein of doctrine jjervading the theory ol this 
 great chemist, which seems to l)e taken up independently of ex- 
 pjixience, and without calculating all the principal relations be- 
 lolfging to the subject : — which doctrine is*, that to bury vegeta- 
 ble manure without' fermenting, and leave it gradually to de- 
 compose in the soil, will prolong its fertilizing power for 
 several se^isons. So it will : — but what will be the intermedi- 
 s^t state of the soil ? Surely the capacity of the land for grow- 
 ing healthy jilants cannot be equal to that of a clean soil where 
 the manure is not applied till it is ready to afford nutriment. 
 
 This part of the theory is in opposition to the practice of 
 rotting turf before it is turned into the soil, or of waiting till it 
 has become rotted before a new crop is introduced. There 
 will be several occasions of adverting to this principle again^ 
 and of viewing every side of it as it may catch different lights 
 in different positions, particularly under Sect. V. By Follow- 
 ini[>\ and the head Management of Manure from the 
 Homestead. j 
 
 V. Bif Fallorving. — Sir Humphry Davy seems to under-rate 
 the utility of fallowing, and to be disposed to recommend the 
 non-fallowing system. 
 
 The following is the substance of the observations occurring 
 in different j^arts of his Work on this subject. (1st.) '* The 
 chemical theory of fallowing is very simple. Fallowing affords 
 no new source of riches to the soil. It merely tends to pro- 
 duce an accumulation of decomposing' matter . which in the com- 
 mo7i course of crops xvoiild be employed as it is formed ; and it 
 is scarcely possible to imagine a single instance in which a culti- 
 vated soil can lie fallow for an entire vear with advantage to 
 the farmer. The only cases where this practice is beneficial 
 seems to be in the destruction of weeds, and for cleansing foul 
 soil ^ 
 
 "• i'lie benefits arising from fallows have been much over- 
 rated. A suinmer fallow, or a clean fallow, may be sometirnes 
 nect-ssury in lands overgrown with ^veeds, particularly if they 
 are sands, — which cannot be pared and burnt with advantage: 
 but it is certainly unprofitable as part of a general system of 
 hustiandry."! , 
 
 (2dly.) " It has been supposed hy some writers, that certam 
 
 * Elemcvits of AgTicultural Chemisty, p. 22. 
 
 tlbid,2?9, 
 
FALLOWING. 27 
 
 principles necessary to fertility are derived from the atmos- 
 phj-rc, .viu;.h are uXiaasted by a succession of crops, and that 
 these are again supplied duriiig the repose of the land, and the 
 exposure of the pulverized soil to the influence of the air : but 
 this, in truth, is not the case. The earths commonly found in 
 soils cannot be combined witn more oxygen ; none of them will 
 unite to azote ; and such of them as are capable of attracting 
 carbonic acid, are always saturated with it on those soils on 
 which the practice of fallowing is adopted. The vague ancient 
 opinion of the use of nitre, and of nitrous salts in vegetation, 
 seems to ha -e been one of the principal speculative reasons for 
 the defence of summer fallows. Nitrous salts are produced 
 during the exposure of soils containing animal and vegetable 
 remains, a id in greatest abundance in hot weather : but 
 it is PROBABLY by the com!)ination of azote, escaping from 
 those remains, with oxygen in the atmosphere that the acid is 
 formed ; and at the expense of an element v/hich would otlier- 
 wise have been converted into ammonia; the cosnpounds of 
 which, as is evident from what is stated under VIII. 2, are 
 much more efficacious than the nitrous compounds in assisting 
 vegetation."* 
 
 (3dly.) " When weeds are buried in the soil, by their gra- 
 dual decomposition they furnish a certain quantity of soluble 
 matter: but it may be doubted, whether there in as- much use- 
 ful manure in the land at the end of a clean falloxv^ as at the 
 time the vegetables clothing the surface were first ploughed in. 
 Carbonic acid gas is formed during the whole time by the action 
 of the vegetable matter upon the oxygen of the air ; and the 
 greater part of it is lost to the soil in which it -was formed^ and 
 dissipated in the atmosphere. 
 
 " The action of the sun upon the surface of the soil tends to 
 disengage the gaseous and tnt- volatile fluid matters contained 
 in it ; and heat increases the rapidity of fermentation : and in 
 the summer fallow^ nutriment is rapidly produced at a time 
 when no vegetables are present capable of absorbing it."f 
 
 (4thly.) "■ Land when it is not employed in preparing food 
 for animals, should be applied to the preparation of manure for 
 plants ; and this is effected bv means of green crops, in con- 
 sequence of the absiorption of carbonaceous matter from the 
 carbonic acid of the atmosphere. In a summer^ s falloxv^ a pe- 
 riod is always lost in which vegetables may be raised, either as 
 food for ani rials, or as nourishment for the next crop ; and the 
 texture of the soil is not so much improved by its exposure as 
 in winter, when the expansive powers of ice, the gradual dis- 
 solution of snows, and the alternations from wet to dry, tend to 
 pulverize it, and to mix its different parts together.":|; 
 
 * Elements of Agricultural Chemistry, p, 240. 
 tTb.id. ^ Ibid. 
 
2H TALLOW IN tt. 
 
 The Reader has now before him the arguments directed hy 
 Sir H. Davy against the praetice ot fallowing, as part of a ge- 
 neral system of husbandry. 
 
 But cannot some of the above object;ions to the giving of a 
 periodical rest to land after an exhausting crop be obviated ? 
 and are not the benelits of a summer fallow, when admitted to 
 be necessary, in some respects undervalued ^ 
 
 In the first place, this eminent philosopher observes, that fal- 
 lowing " MERELY tends to produce an accumulation of decom- 
 posing matter, which in the common course of crops would be 
 employed as it is formed.'" But this accumulation of decom- 
 posing matter is alone a great acquisition ; it is in many cases 
 the precise restorative wanted to keep up the proportion oi ve- 
 getable mould necessary to fertility. Supposing the milder 
 course of crops to employ the decomposing matter as it is 
 formed, — how are plants which depend still more on the nutri- 
 ment lodged in the :-.oil, to be grown in full crops, where the 
 quantity of manure is limited by local circumstances, unless 
 the elements of vj:getation are allowed to accumulate for a sea- 
 son, at periods adjudged proper by a manager acquainted with 
 the power of the soil and the course of crops ? 
 
 Secondly, in opposition to the idea that certain principles ne- 
 cessary to fertilit)- are derived from the atmosphere. Sir Hum- 
 phry enters on a speculative train of reasoning, — against which 
 it would be presumptuous to appeal, had he offered a positive 
 conclusion as a great chemical authority : but some of the as- 
 sumed data — such as that the " earths commonly found in soils 
 cannot be combined with more oxygen" — seem to skirmish with 
 the conclusion [" Nitrous salts". . . to the end of the para- 
 graph ;] — nor has the " vague ancient opinion of the use of nitre 
 and of nitrous salts in vegetation'' been subverted or discoun- 
 tenanced b)- the experiments of modern physiologists, many of 
 whom have found that plants will grow in nitre alone, which is 
 more than the ancient opinion requires in its support. And as 
 to the final inference, — " but it is probably by the combina- 
 tion," &c. the uncertainty disclosed in the word " probably," 
 deprives the argument ot all decisive effect in a practical point 
 of view for although the Professor is acquainted witl\ the ope- 
 . ration of gases as far perhaps as experiment will ever trace it^ 
 the manner in which nitrous salts are produced in soils contain- 
 ing animal and vegetable remains, is but guessed at by him, and 
 not explained to us with the authority of certain knowledge. 
 
 Thirdly, this distinguished Chemist, after virtually admit- 
 ting, that the weeds which were overrunning the land must en- 
 rich it by being buried in its bosom, further observes : — " But 
 it may be doubt r.D, whether tliere is as much useful manure in 
 the land at the end of a clean fallow, as at the time the vegeta- 
 bles clothing the surface were first ploughed in." . , . he Scj:. 
 
FAI.LOWIXG'. 29 
 
 To this speculative objection the answer must necessarily 
 take a speculative turn. 
 
 If there be less manure in the land at the dose of a fallow, 
 the quantity lost must have escaped in the shape ot vapour, and 
 been dispersed in the atmosphere. It may be wortii while t(j 
 inqvjire how far this is to be estimated as a loss i 
 
 In opposition to the theory of Sir Humphry Davy on this 
 point, it is quite consistent with good logic to suppose, that 
 whatever escapes from the dissolviu)^ mass of a dead plant in 
 the form of vapour, and does not fall down to the earth by con- 
 lensation, is easily and most naturi.lly taken up by a new grow- 
 nj; plant from the atmosphere, throu;i;h the leaves ; that is to 
 ^ay, whatever has^ tendency to fly oil' into the air is to be re- 
 ';ovcred by communication with the air. 
 
 On this subject the theory of the author of these remarks is 
 as Ibllows : — 
 
 To form the bulk of a growing plant, — certain Substances 
 comprehended under some of the descriptions of matter com- 
 mon to vegetables, and which appear on analysis to be combined 
 differently in different' species, are taken up by the roots from 
 the soil, and by the leaves from the air, tlirough the medium of 
 congenial fluids : in succulent plants a greater proportion of 
 food is received by the leaves than by the roots, so that even 
 the bulk of the plant, or the basis of the sap, is in such kinds 
 increased chiefly by derivations from the air. 
 
 To imbue a common insipid basis with those distinguishing 
 peculiarities which make different species growing in the same 
 ,oil differ in scent, flavour, and the qualities which are salutary 
 or pernicious in food and medicint, — certain Specific Essen- 
 ces, or volatile aeriform atoms, invisible either from being co- 
 lourless or minutely divided, are taken up entirely by the leaves 
 from the air; the character of the plant having been originally 
 fixed by a portion of the peculiar essence being lodged in the 
 seed so as to attract to it only volatile particles of its own na- 
 ture.* 
 
 H';nce in mixed masses of manure, the manure may be con- 
 sidered better adapted for general purposes, when the volatile 
 properties peculiar to specific plants and to animal bodies have 
 ::scaped, and when the residuum is nothing more than the mat- 
 ter common to vegetable and animal bodies. 
 
 It may seem to be a loss, that the gaseous essence, escaping 
 into the atmosphere, is dispersed over an immeasurable region 
 of air, and carried by winds over the face of the earth, instead 
 of being retained for the enrichment of a particular field. To 
 
 • 'I'liis tlicon' will f^o a considerable way towards afTording a solution why 
 Jic hlossoms and fruit of" a graft should preserve their distingiiishinjj pcouliari- 
 .ics, unaltered by connexion with the stock* 
 
so FALLOWING. 
 
 this it may be answered, that che ^ases of which the air is con- 
 stitued — oxygen, azote, and carbonic acid gas — though differing 
 in ilieir specific gravity ar rather levity, arc found to be com- 
 bined in any cubical quantity of air in a proportion which ne- 
 ver materially varies ;* and it is quite reasonable to suppose, 
 that the volatile salts or spirits, or aromatic principles, which 
 constitute the essences of plants, arc distributed equally over 
 the atmosphere by the same law. The quantil^ of volatile essence 
 floating within reach of the attraction ol an individual plant must, 
 ^indeed, be allowed to be evanescent even to the confines of no- 
 thingness, when the transparency of the air is considered, and the 
 tnultiplicity of difl'erent essences of which infinitel) small divi- 
 sions are supposed to be floating in it. But if^on the other hand, 
 we advert to the elastic nature of the air, and the jiroperty 
 which it is found to have ot always preserving its natural equi- 
 librium, the most scanty provisions of volatile food in the vici- 
 nity of a plant is abundance. Thus, suppose a plant to take up 
 carbonic acid gas with great avidity ; although the proportion of 
 carbonic acid gas is extremely small, yet the plant cannot drink 
 tip the quantity in immediate contact so fast, but the same quan- 
 tity will be constantly preserved in the air surrounding it ; for 
 gas of the same nature is incessantly pressing into the temporary 
 void where the interchange of natural air is unrestricted. The 
 supply of a peculiar essence to plants, by the medium of the 
 common air, may be rendered sufficiently ample by obedience 
 to the same law. 
 
 It may therefore be one of the benefits of a fallow, to lose 
 every thing which can escape by a free exposure of the putrefy- 
 ing remains which promiscuously accumulate in a soil. 
 
 On the hypothesis which has just been sketched, the objec- 
 tion of Sir H. Davy, that " the action of the sun upon the sur- 
 face of the soil tends to disengage the gaseous and the volatile 
 fluid matter that it contains, and heat increases the rapidity of 
 fermentation," — may be enlisted among the arguments in favour 
 of a summer fallow. In cases where a restorative course is de- 
 sirable, the objector also becomes an ally who urges, that " in 
 the summer fallow nutriment is rapidiiy produced at a time 
 when no vegetables are present capable of absorbing, it." 
 
 Fourthly, with regard to the superior utility of ploughing in 
 Green Crops, as recommended in the Elements of Agricultu- 
 ral Chemistrv, instead of a fallow : — There can be no difference 
 of opinion where the land is poor, or exhausted, without being 
 foul; that is to say, when it wants recruiting with manure, but not 
 cleaning of root-weeds to the full depth of the soil. Plants which 
 quickly decompose, such as the lettuce, are most conducive to 
 
 * In a given volume of air, their pro^jortions arc usually found to be : Oxygen 
 3^^ ; azote J^^ ; carbonic acid gas ^^^ max. ^^^ min. 
 
FALLOWING. 31 
 
 ihe object of exciting a fermentation in fibrous woody remainis 
 as well as enriching the land. This subject has been already 
 touched under Sect. IV. 
 
 To return to 'the question of fallowing. It is merely to dis- 
 embarrass the practical manager, that so much has been said by 
 way of theory against an hypothesis on non-JflUowing^ which 
 is made to depend on assumptions from chemical principles 
 too little capable of proof from experiment to be safely adopted 
 in this branch of agriculture. 
 
 Some of the incidental statements, in the above abstract from 
 the Professor's Lectures, are decidedly adverse to practical 
 maxims in which most farmers, and the majority of writers on 
 husbandry, including the Reports from Agricultural Societies, 
 concur ; — the statements, for example, that ' sands are benefited 
 by a summer fallow more than clays ;' and that the ' land is not 
 richer at the end of such a fallow than it was before.' On the 
 contrary, the conclusion to which the registered courses of pro- 
 fitable husbandry lead, is very much like the following sum- 
 mary. 
 
 1. Land is uniformly recr^iited during a fallow : this is pro- 
 ved by the circumstance, that, in all soils, a much leas quantity 
 of dung is necessary after a sutnmer fallow ; and on some lands 
 none is wanted ; nay, the experienced Cally is of opinion, that 
 dunging naked fallows is in many cases better dispensed with, 
 and has often, in tolerable loam^, made the crop to fail. 
 
 2. Clays are unfit for green crops, the substitute for a sumr 
 mer fallow ; and hence are necessitated to adopt the latter, in 
 rotation with white crops.* A winter fallow merely is, indeed, 
 an excellent thing in light grounds, and as a preparation for 
 spring wheat ; but it will not do with clays, which require a 
 thorough drying and pulverizing, before they can profit by the 
 falling juices, which would only render the earth more hard and 
 compact. A summer fallow is, therefore, more proper for this 
 soil.f 
 
 3. Light soils only can dispense with fallows. The ques- 
 tion therefore is narrowed to this compass : Whether the benefit 
 of a summer fallow, on a sandy or other light soil fit for green 
 crops, is equal to the loss of a year's rent» or to the difference 
 between the profit of a green crop and the rent for one year 
 paid on a naked fallow ? The general conclusion is, — that it i? 
 not ; and that a summer fallow for light soils is too costly. 
 
 By a rotation of crops, every ingredient in the manure ap- 
 plied is successively turned to profit; for those parts of it 
 which are not fitted for one crop remain as nourishment for 
 another. 
 
 • Letter by tlie President of the Workington Agricultural Society, dated TSav, 
 2D, 1814. 
 
 t Pfiilosophical Magazine for Jan. 1815. A<>. 1. p. 12. 
 
IJ2 FALLOWING. 
 
 Different soils refiuJrc a diiriient rotation, and the ])vacttce of 
 one district allord no ubsolutr rule lor another. Local circiim- 
 rilances will always nilluenci- the course of crops ; jet a survey 
 of some of" the rotati(jns, which alter long trial are found lo be 
 repeatedly beneficuil on the principal sorts (<f land, tends lo en- 
 large the resources of farming ; and if brought from a distant 
 part of the island, the chance of" a benificial exchange of infor- 
 mation, in some respects new, is increased. 'J'lie following 
 coinii.unioations are gathered from a voluminous w()rk, entitled 
 (unicral Ril)ort oj' the Ai^-riculturc of Scolland^ published under 
 the superniteiidanee ol bir John Sinclair. 
 
 Bknkj IT oi' (jRCKN Cuoi's. — " ''I'he introduction of Turnips 
 and Clover has been the means of" rendering productive those 
 inferior soils which it was impossible to cultivate under the old 
 system of successive corn crops. Even on land of a better 
 quitlity, the crops which succeed these are so much more abun- 
 dant, that it is probable as many bushels of corn now grow on 
 the half of a given extent of ground as were formerly raised' 
 on the whcile. In this vie w alone, almost the whole value of 
 the turnips and clover may be said to be a clear gain. Fallow 
 has been banished from all dry soils by turnips ; and where land- 
 is laid down to pasture, one acre of cloVer and rye-grass will 
 fatten more cattle than could barely exist on ten acres left full 
 of weeds to be casually sown, after several years, with natural 
 grasses. 
 
 " When turnips were first introduced on farms, and for some 
 time after, the most common apj^lication of them was to the 
 fattening of cattle. Sheep did not then form any important 
 part of the stock of arable land : but on light soils the full be- 
 nefit of this crop was not ol)tained, until it had become the. 
 practice to consume the greater i)art of the crop on the ground 
 by sheep. The poorest sandy soils seldom fail to yield an abun- 
 dant croj) of corn after turni])s thus consumed on the ground. 
 They are thus at once manured and strengthened in the sta- 
 ple. 
 
 " On dry loams, the best practice is a medium between the 
 old and the new ; and the crop is divided between the sheep- 
 and the fbld-yard, by drawing off and leaving a fe\v ridglelt. 
 alternately. 
 
 " I'he vast addition made both to the quantity and the qua- 
 lity of the dunghill, by the (onsumption of green clover and 
 turnips, powerfully recommends them; and turnips accordingly 
 arc cultivated for this very purpose, on soils but little adapted 
 to their growth as an edible root. "When grown on clayey soils, 
 the wholg crop is still carried to the fold-yard, for the object of 
 converting the haulm into manure. 
 
 '^ So the best mode of consuming clover and rye-grass is II 
 Ivibture it, especially on tlun dry soils; compared with whicli 
 
FALLOWING. 33 
 
 the mode of reserving the entire crop for hay is very unprofita- 
 ble. 
 
 " On lands less fit for pasturing, deep loams and clays, soil- 
 ing is resorted to. A considerable portion of the grass is cut 
 green for horses and milch cows ; and in some instances, both 
 for rearing and fattening ot cattle. This economical use of the 
 grass in the homestead augments and enriches the dunghill." 
 
 ROTATION WITHOUT A SUMMER FALLOW. 
 
 " The most common rotation on the best dry soils is one of 
 four years. 1. Wheat or oats (assuming the previous crop to 
 have been an artificial grass.) — 2. Turnips. — 3. Wheat, barley, 
 or oats. — 4. Clover and rye-grass ; one moiety of the farm be 
 ing under green crops, and the other under white crops. But 
 on siliceous sandy soils (flinty sand being the abounding ingre- 
 dient) it is necessary to retain the clover and rye-grass division 
 for some years in pasture, unless more manure is applied to such 
 land than can be returned jrom its own produce.''^ 
 
 ROTATIONS WITH A FALLOW. 
 
 ** On clayey loams the rotations are more varied. On strong 
 clays, beans is the best relieving succession crop ; and although 
 it cannot be proposed as a perpetual substitute for a summer 
 fallow, in alteration with wheat or any other exhausting culmi- 
 ferous crop, — yet when drilled, and hand and horse-hoed, beans 
 supersede the necessity of fallowing oftener than once in a 
 rotation of six or eight years. Wheat and beans have been 
 taken alternately for a series of years, even as many as eight, 
 on the best soils ; but the most frequent courses art of four 
 and six years. The four years' course is renewed in this 
 order: 1. Fallow; 2. Wheat; 3. Clover; 4. Oats. The six 
 years' course revolves, with nice adaption to every crop, thus : 
 1. Fallow; 2. Wheat; 3. Clover and Rye-grass; 4. Oats; 
 5. Beans ; 6. Wheat. Or the six years' rotation is some- 
 times varied thus : 1. Fallow; 2. Wheat; 3. Beans; 4. Bar- 
 ley or Oats ; 5. Clover and Rye-grass ; 6. Oats : but by this 
 arrangement the land is neither so clean, nor so w ell pulverized, 
 as it should be in preparation for clovers. On clayey soils a 
 nomplete fallow is considered as the basis of every profitable ro- 
 tation crop by the most judicious farmers of Scotland ; and 
 according to their concurring experience, on wet cohesive soils, 
 however good the course of tillage, no trials, made upon a large 
 scale, to postpone a fallow for more than eight years, have hi- 
 therto been successful in that part of the island." 
 
 Some of the Papers in the above-mentioned General Report^ 
 which record this result, allude to the climate as being wjet, 
 
 r 
 
S4 I^ALLOVVING. 
 
 and humid for a greater portion of the year than in most parts 
 of England ; and in some degree attribute the failure, with 
 them, of the jion-fallowijig system to that cause. But having 
 no system to manufacture for universal and perpetual applica- 
 tion, without regard to the quality of the land, or the local re- 
 sources for manure, — comprehensive views, a candid indepen- 
 dence of theory, and an exact balance of the adventure, and 
 returns under both methods, may have a greater share than 
 the climate in their decision. 
 
 Indeed it would be easy to multiply quotations from intelli- 
 gent writers on this side the Tweed, the tenor of which agrees 
 with the above, both in the inclination to dispense with fallow- 
 ing, as far as it can be done with profit, and in the admis- 
 sion that on certain lands a periodical fallow conduces to 
 eventual gain. 
 
 Very striking circumstances are connected with the Letters 
 on Agriculture^ from which we are going to borrow almost the 
 counterpart of the above. First, these Letters are not behind 
 the intelligence of the present day, though written five-and- 
 twenty years ago : for rejecting some of the speculative notions 
 which were then in fashion, the writer took at once the tfenable 
 ground to which experimental agriculturists have in general 
 reverted. Secondly, they are attributed to the pen of His 
 Majesty George the Third ; — a king who, though placed by 
 afflictions beyond the reach of flattery, is still praised and revered 
 by his people.* ^ 
 
 Extracts relating to Rotations without Fallow. 
 
 " The dispute which has lately arisen on the subject of sum- 
 mer fallows has made me secretly wish that Mr. Ducket, the 
 able cultivator, of Petersham in Surrey, would have communi- 
 cated his thoughts not only on that subject, but would have be- 
 nefited the public by a full explanation of that course of hus- 
 bandry which has rendered his farm at Petersham, which has 
 been now above nineteen years in his hands, so flourishing, 
 though his three predecessors had failed in it.'' 
 
 " His course of husbandry seems to be the employing clover, 
 turnips^ and rye, as fallow crops, and as intermediate ones be- 
 tween wheat, barley, oats, and rye ; changing them according 
 to the nature and quality of the land." — Letter dated 1st Jan. 
 1787. 
 
 " He would in general reject the practice of falloiving on 
 light soils ; as feeding-crops are better, — from the cattle, while 
 
 * Mr. Young had the honour of givh>g them to the public in his Annals of 
 ^griciiUue. 7th vol., to whom they were sent with all the exterior marks of an 
 ordinary correspondent : they were subscribed " Ralph Robinson," and dated 
 from Windsor. 
 
FALLOWING. 35 
 
 -consuming the crop, treading the soil, and rendering it more 
 compact and firm, which a light soil requires. . . . Besides, this 
 enables the farmer to keep a larger stock of cattle, which increases 
 his quantity of manure." 
 
 " Thus his land, although never dormant, is continually re- 
 plenished with a variety of manures, and thus unites the system 
 of continued pasture with cultivation." — Letter dated otii Mc(rchf 
 1787. 
 
 Extract relating to Winter Fallows. 
 
 It is to be premised that the texture of some lands gives them 
 a middle nature between light and heavy ; or else from local 
 causes- there is no dependence that they can be kept sufficiently 
 dry in winter for a feeding-crop. " Many soils may be impro- 
 ved by winter fallows. This may be practiced by ploughing 
 immediately after the grain crop is off in a dry season ; and by 
 being well water-furrowed during the winter ; and by proper 
 dressings in the spring : but Mr. Ducket does not think this 
 method equal to a feeding-crop of rye, turnips, or tares." — Let- "*" 
 ter dated 5th March^ 1787. ^* . 
 
 Extract relating to Summer Fallows. 
 
 The joint effect of this and the preceding passage is the more 
 remarkable, because the Editor of the Annals of Agriculture 
 appended to the first Letter the Note which is exhibited below.* 'v 
 The note bespeaks the echo of a preconceived opinion : but his ''^,^, 
 Correspondent had a mind independent of that system which *i- 
 
 would invert, instead of modifying and augmenting, the " ga- 
 thered wisdom" of a hundred generations. This reply is a 
 pointed correction of the mistake in regard to Mr. Ducket. 
 
 " He thinks fallows necessary for strong soils, as the clods 
 of the earth cannot be well broken to pieces without being some- 
 time exposed to the air." — Letter dated 5th March^ 1785. 
 
 As in gardens the land can be kept clean by the hoe, and the 
 renovation by manure is more under the power of the cultiva- 
 tor, a winter tallow is in most cases sufficient. 
 
 VI. By Irrigation. — Irrigation is often found to be beneficial 
 under two different kinds of circumstances ; being resorted to 
 with different intentions : 
 
 • " I have at various times, during tlie last fifteen years, viewfed with groat 
 attention the husbandry of the very ingenious Mr, Ducket. I took notes of 
 what I saw for my private information, but did not publish them, as I thought 
 I perceived a disinchnation in that gentleman to have them so brought for- 
 ward ; and on some points, he expressly desired me not. I am glad to find by 
 this memoir (fpr which the Pubhc is much indebted to the author) that he has 
 relaxed in this particular. I wish much that Mr. Robinson, as he has broken 
 the ice, would proceed, and in particular give his courses of crops; and ex^ 
 plain, in particular, his nUer rejection offalloivs," 
 
36 IRRIGATION. 
 
 1. To obtain an alluvial deposit left by the water. In winter, 
 on land where no crop or seed is lodged, but where annual or 
 other plants are to be cultivated in the following season : or in 
 autumn, whenever the crop is off the ground ; or at any time 
 when the soil of a fallow requires to be strengthened, this sub- 
 stituted for a more expensive manure may be applied. Also 
 meadows may be floated at the seasons judged proper, accord- 
 ing to the circumstances ot the land, the quality of the water, 
 and the constitution of the grass. The practice of the Fiorin 
 School (founded by Mr. Richardson,) as reported in the Agri- 
 cultural Magazine, N. S. No. 6. is in substance thus : " Some 
 par s of the Fiorin to be irrigated in November : others in Feb- 
 ruary : the floating to be continued at intervals throughout the 
 summer ; the water to be one xveek^ or less^ on the meadow, and 
 txvo weeks off it : but the grass not to be mown till October." 
 The result is not stated, in the most favourable event, this me- 
 thod could only be proper for grass which naturally grows on 
 bogs, and where it is intended to be husbanded as a winter food. 
 
 2. In summer, a light shallow irrigation may be directed over 
 land occupied with growing plants, where a long continuance of 
 dry weather makes it desirable to draw out such a resource. 
 This is merely watering ; and not irrigating, to obtain an allu- 
 vial manure. 
 
 The winter irrigation of meadows is, in many districts, the 
 effect ot a local flood, which the farmer cannot prevent nor ma- 
 terially control : but the temporary mischief is followed with a 
 rich compensation. AH plants which are not aquatic, if they 
 are covered over the tops with water, have their growth imme- 
 diately arrested ; and if they thus continue inundated during, 
 the winter months, the majority die down to the root, having 
 the herb completely dissolved, and even the roots of others pe- 
 rish : but the vegetable matter of the plants thus decomposed 
 adds to the depth and fertility of the soil ; and such plants as 
 survive to shoot again in spring, derive an advantage from the 
 decayed substance of the others, as well as from the alluvial 
 soil deposited by the water. 
 
 Sir Humphry Davy's, theory on irrigation partly corresponds 
 with the above ; but one good effect which he attributes to the 
 flooding of meadows in winter, is quite opposed to the admis- 
 sion of temporary injury to plants not aquatic. His words are : 
 *' In very cold seasons it [the inundation] preserves the roots 
 
 and leaves of the grass from being affected by frost 
 
 Water is of greater specific gravity at 42** of Fahrenheit than 
 at 32**, the freezing point ; and hence in a meadow irrigated in 
 winter, tht water immediately in contact with the grass is rarely 
 below 40°, a degree of temperature not at all prejudicial to the 
 living organs of plants. [He proceeds to relate the following 
 experiment.] In 1804, in the month of March, I examined the 
 
IRRIGATION. 37 
 
 « 
 
 temperature of a water meadow near Hungerford, in Berkshire, 
 by a vvr^ delicate thermometer. The temperature of the air, 
 at seven in the morning, was 29">. The water was frozen above 
 the grass. The temperature of the soil below the water, in 
 which the roots of the grass were fixed,* was 43°." — This in- 
 sulated observation is certainly not enough to support the prin- 
 ciple laid down by the Professor. As the water is reduced in 
 depth, in the course of its subsiding and evaporating, there 
 must happen many occasions on which the grass would lie al- 
 ternately in shallow water, and alternately in thin ice, partly 
 covered and partly exposed, and ready to dissolve as soon as 
 any heat acts upon the moisture. 
 
 It concerns the practical farmer who has meadows which ht 
 can either float, or keep dry, to decide by close persoral exami- 
 nation, in what manner gi'asses not aquatic are affected by lying 
 under water during the frosts and other vicissitudes of v. inter : 
 of this the state of the grass at the subsiding of the water in 
 sprmg, and the weight of the crop, is the proper criterion.] 
 
 The Professor says in another place : "■ When land has been 
 covered by water in the winter, or m the beginning of spring, 
 the moisture that has penetrated deep into the soil, and even 
 the subsoil, becomes a source of nourishment to the roots of 
 the plant in summer ; and prevents those bad effects that often 
 happen to lands in their natural state from a long continuance 
 of dry weather.":}: The alluvial matters which the water may 
 have diffused through the veins of the land is undoubtedly be- 
 neficial : but, were the water which has conveyed them to stag- 
 nate in the subsoil, it would be more pernicious to most plants 
 than the droughts of summer. 
 
 We now come to some other communications by this distin- 
 guished Chemist ; the substance of which may be given with- 
 out protest or comment as principles consistent with experience 
 — although they are placed on an original foundation, which 
 enlarges the sphere in which irrigation may be safely applied. 
 
 " When the water used in irrigation has flowed over a calca- 
 reous bed, it is generally found impregnated with carbonate of 
 lime ; and such water tends, in that respect, to ameliorate a soil 
 in proportion as any of the modifications of lime and charcoal 
 v/ere deficient ; but where these are already in excess, water 
 charged with a limy sediment should be withheld j while wa- 
 
 • Elements of Agricultural Chemistry, p. 239. 
 f " Should the frost set in when the water is on the land, so that some spots 
 should be covered with ice for some days, the spot so covered with ice will 
 be of a darker green, and appear more healthy in the spring than the rest of 
 the field. But when they come to mow the hay, the crop will be considerably 
 less than that on the other parts of the field that were not covered with ice." 
 0)1 Watering JMeadoivs in Brecknockshire. Report by J\lr, John Clark to tile 
 Board of Jlgricidture, 1794. 
 
 ^ Elements of A^icultural Chemistry, p. 238. 
 
38 APPLYING EARTHS AS MANURES. 
 
 ter impregated with sand, clay, gypsum, or particles of iron, 
 would be beneficial. 
 
 " Common river water generally contains a certain portion of 
 the constituents of vegetables and animal bodies ; and after 
 rains this portion is greater than at other times : it is habitual- 
 ly largest when the source of the stream is in a cultivated 
 country.* 
 
 " In general, those waters which breed the best fish are the 
 best fitted for watering meadows ; but most of the benefits of 
 irrigation may be derived from any kind of water — -provided 
 the soil be not already overcharged with the prevailing ingredi- 
 ent in the deposit left by the water ; and provided, on the other 
 hand, that the matter of the soil and the matter of the depo- 
 sit are not pernicious when combined. These are general prin- 
 ciples : 1. That waters containing ferruginous impregnations 
 (particles of iron) tend to fertilize a calcareous soil. 2. Fer- 
 ruginous waters are injurious on a soil that does not effervesce 
 with acids, which is one of the tests of the presence of lime. 
 3. Calcareous waters, which are known by the earthy deposit 
 they afford when boiled, are of most use on siliceous soils, or 
 other soils containing no considerable proportion of carbonate 
 of lime.f 
 
 Supposing the farmer to have a complete command over con- 
 tiguous water containing a suitable alluvial deposit, he may 
 render a cultivated level, which requires rest and a cheap ma- 
 nure, extremely productive with comparatively little labour, by 
 irrigating on the above principles. 
 
 VII. By applying' Eafths as Manures. — When any decom- 
 ' posed mass of stone or earth is laid upon or turned into the 
 cultivated clod, with the object — eitherof furnishing a solvent 
 to the remains of animal or vegetable matter which encumber 
 the soil by their slow decay, or of enriching the land with some 
 substance which is apparently taken up by specific plants as 
 FOOD ; then the earthy matter is applied as manure. This is a 
 distinct province from that of merely applying earths to mend 
 the texture of the soils as under I. But sometimes the two 
 designs will coincide. Closely connected with the theory of 
 manures is the inquiry. What is the true food of plants ? 
 
 " The chemistry of the more simple manures, the manures 
 which act in very small quantities — such as gypsum, the alka- 
 lies (which include potash and soda,) and various saline sub- 
 /Stances — has hitherto been exceedingly obscure. It has been 
 generally supposed, that these materials act in the vegetable 
 economy in the same manner as stimulants in the animal econ- 
 omy, or perhaps in some relations as solvents ; but that in ei- 
 ther case they merely render the common food more nutritive. 
 
 * Elements of Agricultural Chemistry, p. 238, 
 t^bid, 239. 
 
ON THE FOOD OF PLANTS. 39 
 
 It seems, however, a much more probable idea, that they are 
 actually a part of the true food of plants, and that they 
 supply that kind of matter to the vegetable Jibre rvhich is analo- 
 gous to the bony 7natter in animal structures.''''* The probability 
 that Sir H. Davy has assigned to these substjmces their true 
 office in vegetation, is much heightened by the earthy matters 
 aftbrded by different plants on analysis. On a similar principle, 
 the benefit of a small proportion of shell marl, in the compost 
 for the pine apple, is accounted for in Abercrombie's " Practi- 
 cal Gardener."! 
 
 The epidermis of the rattan is stated to contain a sufficient 
 quantity of flint, to give light when struck by steel ; and some 
 small proportion of minutely pulverized flint exists generally in 
 the epidermis of hollow stalked plants, where it is of great use in 
 serving as a support, and seems to perform an office in the feeble 
 vegetable tribes analagous to that of the fine thin shell by which 
 many insects are defended. 
 
 As a prelude to a survey of the effects of different earths as 
 manures, it may be serviceable to glance at those constituents 
 in the kingdom of nature, which appear to be the chief agents 
 in vegetation. 
 
 Before the true constitution of Water was known, some phi- 
 losophers and speculative horticulturists had supposed, that all 
 the products of vegetation might be generated from water ; an 
 opinion which practical experiments have shown to be falla- 
 cious. This ancient error, and the revival of it by several 
 eminent physiologists in the 17th and 18th centuries,:|: was 
 founded on correct observations, in regard to the following 
 points : — 1. The presence of moisture is necessary to germina- 
 tion. 2. Water is the vehicle of various particles of nourish- 
 ment derived both from the air and from the soil ; ^nd no ma- 
 nure can be taken up by the roots of plants unless it is present. 
 3. Various vegetables, a greater number than can be easily na- 
 med, have been found to grow vigorously with the roots in con- 
 tact with water without earth. 
 
 In the same manner, the existence of air-plants, — the misin- 
 terpretation of various phsenomena observed in experiments on 
 
 * Elements of Agricultural Chemistry, p. 19. 
 
 ■f Hot-house, Pinery, p. 601. The first edition of tlie " Practical Garden- 
 er," was published before tlie Elements of AgriculUiral Chemistry appeared. 
 
 + Van Helinont, Boyle, Bonnet, Duhamel, Tillet, and Lord Karnes, zealously 
 endeavoured to establish the theory of water being the only food of plants -, 
 and Braconnot quite recently, by experiments with distilled water. Margraf, 
 Bergman, Kirwan, Hassenfratz, Saussure, San Martiuo, and Davy, have expo- 
 sed the fallacies of this theory. Every pound of rain water contains one grain 
 of earth, besides other impregnations. Plants raised from pure water will 
 vegetate only a certain time, and never perfect their seeds. Bulbous roots, 
 which are made to grow in water, if not planted in earth every other year, 
 refuse at last to flower, and even to vegetate. 
 
40 ON THE FOOD OF PLANTS^ 
 
 the atmosphere, and the repeated demonstrations that without 
 the presence ot" ah', or of oxygen gas, neither the germination 
 of seeds can commence, nor the offices of vegetation proceed, 
 — have led many inventors of' new hypotheses on the growth 
 and food of plants, to attribute to the agency of Air greater 
 effects than is consistent with the daily evidence that many 
 other things are equally indispensable. 
 
 So the productive power of mere Earth has been exagge- 
 rated. Jethro TuU, the ingenious author of the system 
 of horse-hoeing, and after him Duhamel, having observed 
 the excellent effects produced in tillage by a minute di- 
 vision of the soil, and by the pulverization of the broken clod 
 by exposure to dew and air, were misled by carrying these 
 principles too far. Supposing earth to be the only food ot 
 plants, they contended, that by finely dividing the soil, any 
 number of crops might be raised in succession from the same 
 land, so as to render periodical fallows unnecessary, Duhamel 
 attempted to prove that vegetables of every kind could be raised 
 without manure : but he lived long enough to alter this opin- 
 ion ; his subsequent trials led to the mature conclusion, that 
 no single material constituted the food of plants. The general 
 experience of farmers had long before convinced unprejudiced 
 theorists of that as a fundamental principle ; and also that ma- 
 nures were absolutely consumed in the growth of plants. 
 
 The principles of Sir Humphry Davy are nearly, but not im- 
 plicitly adopted in the following recapitulation and synthesis. 
 
 Water, and air, and earth (as the chief depository of solid 
 organic materials,) all operate in the process of \«getation. 
 No one principle affords the pabulum of plants : it is neither 
 water, which may form the basis of their fluids, for it exists 
 in all the products of vegetation; nor air, of which they give 
 out various forms on distillation, such as oxygen, and azote, 
 and inflammable gas ; nor charcoal, which is found on analy- 
 sis to be a principal constituent of plants ; nor the particles of 
 flint, and of gypsum, at other times of lime, found in the stems 
 of most vegetables. In all cases, the ashes of plants contain 
 some of the earths of the soil in which the plant grew ; but 
 the earthy particles never exceed y^ in weight of the vegeta- 
 ble burnt. The soil is the great laboratory in which the main 
 part of the food for common plants, or that which conduces to 
 their gross bulk, is lodged and prepared. In proportion as 
 some kinds of vegetables are found not to exhaust a soil, 
 they must be supposed to derive organic materials from the air, 
 as well as from the rain or other water with which their vessels 
 may come in contact ; further, some contrilmtions to the sub- 
 stantial juices of all plants may float among the constituents of 
 air. To all kinds of leaves and fruit, the atmosphere may pos- 
 
ON THE FOOD OP PLANTS. 4l 
 
 iibly be the medium of the subtile and volatile parti- 
 
 cles WHICH constitute FLAVOUR AND AROMATIC ESSENCE 
 
 * 
 
 The colour of plants, in regard to the constant repetition of 
 habitual tints, may depend greatly on their free communication 
 with light : but the colour of the foliage, flowers, and fruit, is 
 also affected by accidents in the soil and climate. The princi- 
 ples of vegetable matter which escape from putrefying plants, 
 are either soluble in water or aeriform ; in the one state, they 
 form the most useful part of manure j in the other, they swim 
 in the atmosphere ; in both states, they are capable of being as- 
 similated by the organs of contiguous vegetables : for plants 
 take up the elements found in thtir composition, either by their 
 roots from the soil, or by their leaves from the air. 
 
 The substances found in plants on analysis may be divided 
 into — 1. Those which constitute the hard mattf-r or frame of 
 the plant. 2. Those wbich are eminently, if not soLly, the 
 nutritive materials, whether in the form of dry solids, soft 
 pulp, or juice. 3. Those which serve as condiments, and con- 
 tribute to diversify the scent, flavour, colour, and medical 
 properties. 
 
 The first class includes the simple earths, the earthy bases of 
 compound substances, metallic oxides, and the basis of woody 
 and vegetable fibre, great part of which is carbon. It has been 
 already mentioned that the eartliy , matter never exceeds one 
 fiftieth part in weight of the whole plant, and it is commonly 
 much less ; lime and flint are found the most frequently ; mag- 
 nesia more rarely ; and clay most seldom of all. No other 
 metallic oxides occur than those of iron and manganesum. — ■ 
 Charcoal is a principal constituent in all plants. 
 
 The second class comprehends several substances which are 
 common to the animal as well as the vegetable kingdom, and 
 therefore may be regarded as directly nutritive to animals ; 
 along with a great number not generally present in vegetables 
 to any sensible degree, although abundant in particular plants : 
 these are, farina, or the basis of starch ; gluten, or paste ; gura, 
 or mucilage ; gelatine, or the matter of jelly ; (these three are 
 not always distinguishable;) albunen, resembling the white of 
 an egg ; sugar ; water ; wax ; resin ; fixed oils ; fungin, a prin- 
 ciple detected in the cucumber, abundant in mushrooms ; and 
 extract an indefinable substance, changing with the plant ana- 
 lysed. 
 
 The third class consists of acids, alkalies, and soluble salts ; 
 — of these the most usual is sulphuric acid, combined with sul- 
 phate of potassa ; likewise common salt, and phosphate of lime. 
 The following seem to belong to this class, though sometimes 
 
 • That is, such as are proper to the plant ; for a rank soil may deteriorate 
 the flavour of edible produce by conveying through the roots some remaining 
 juices of % foreign substance. 
 
 F 
 
42 CAUSTIC LIME AS A MANURE. 
 
 in intimate combination with substances under the first or 
 second : — tannin, or the matter tanning leather ; indigo, and the 
 various colouring matters ; camphor ; the bitter principle ; the 
 narcotic principle, or opiate ; volatile oils. 
 
 In addition to all the elementary parts actually found, some 
 aroma, or fugitive essence, which would belong to the third 
 class if it could be detained, may go off in a form thinner than 
 air, too subtile to be weighed or measured. 
 
 The accumulation in a plant of the first class of things in a 
 due and healthy proportion, may depend principally upon the 
 soil, as a mixture of earth ; of the second, upon the manure ; 
 of the third, in a slight degree upon the local climate, but emi- 
 nently upon the power natural to the plant for attracting pecu- 
 liar particles in the earth and air. 
 
 After these introductory remarks on the chief agents in ve- 
 getation, it will be more easy to explain the operation of the 
 different earths, or species of decomposed stone, which are laid 
 upon lands as manure. 
 
 1. Lime as a solvent. (Quicklime.) — Lime, when first 
 burnt, has a caustic property, speedily decomposes vegetable 
 and animal fibre, and is soluble in water. After burnt lime 
 has been exposed to the atmosphere a determinate time, it be- 
 comes mild, by taking up Ciirbonic acid ; loses its solubility ; 
 and becomes chalk, or carbonate of lime. 
 
 When newly burnt lime is exposed to the air, it soon falls 
 into powder; in this case it is called Slakt-d Lime. The same 
 effect is at once produced by pouring water upon it, when it 
 heats violently, and the water disappears. 
 
 Slaked lime was used by the ancient Romans for manuring 
 the soil in which fruit-trees grew. Nevertheless caustic lime 
 is pernicious to vegetation, as far as it comes in contact with a 
 growing plant. Where acid vegetable mould — a radical bane 
 in some marshes, moors, and peat-lands — requires correction, 
 proceed as under I. 1. 
 
 When quicklime, i. e. lime either freshly burnt or slaked, is 
 mixed with any moist fibrous vegetable matter, there is a strong 
 action between the two substances ; and they form a kind of 
 compost, of which a part is usually soluble in ater. Thus 
 lime renders matter, which was comparativeh' inert, nutritive ; 
 and as charcoal and ox}^gen abound in vegetable matters, the 
 lime is at the same time converted into carbonate of lime.* 
 So burnt lime, in its first effect, decomposes animal matter, 
 and seems to accelerate the progress of such matter to a capa- 
 city of affording nutriment for vegetables : gradually^ however, 
 the lime is neutralized by carbonic acid, and converted into a 
 substance analagous to chalk ; but in this case it more perfectlv 
 
 • Elements of Agricultural Chemistry, p. 216. 
 
MILD, LIME AS A MANURE. 43* 
 
 Vnixes with the other ingredients ot the soil, and is more ]ier- 
 vadingly diffused, more finely divided, than mere chalk artifi- 
 cially applied. Burnt lime is probably more benelicial to land 
 tontaining much woody fibre or animal fibrous matter^ than any 
 calcareous subsiance in its natural state.* Thus is quicklime 
 efficacious in iertiiizing peats, and in reducing under tillage soils 
 abounding in hard roots. But when animal or vegetable re- 
 mains are destitute of fibrous matter, so as not to require a 
 powerful solvent, or when their bulk is not in too large a pro- 
 portion, or their tendency to putrescency excessive and noxious, 
 the application of quicklime is an unnecessary reduction of their 
 strength ; therefore to cover or mix them with any simple 
 earth, or stone pulverized without burning, will be better. — See 
 " 2. Mild Lime:" Lime moistened with sea-water yields 
 more alkali (soda) than when treated with common water ; and 
 is said to have been used in some cases with more benefit as 
 manure. f 
 
 It is most important to the Agriculturist to be apprised of the 
 difference in the operation of common limestone, which is of a 
 pure white colour, and another kind of limestone which has a 
 brown or pale yellow tincture : for a disclosure of the cause of 
 this difference, the public are indebted to Mr. Tennant. It had 
 long been noticed, that a particular species of limestone found 
 in the north of England, when applied in its burnt and slaked 
 state to land, in considerable quantities, either occasioned abso- 
 lute sterility, or considerably injured the crops for many years. 
 Mr. Tennant, by a chemical analysis, discovered that this kind 
 of limestone differed from the common, by containing magne~ 
 ■Stan earth : and from several horticultural experiments, he as- 
 certained that magnesia, applied in large quantities, in its caus« 
 tic state, is pernicious to vegetation. Under common circum- 
 stances, the lime from the niagnesian quarry is, however, used 
 in small doses, upon fertile soils, with good effect ; and it may 
 be applied in greater quantities to soils containing a very large 
 proportion of vegetable matter.:): See, fui'ther, " 3. Magne- 
 sia ;" also soaie restraints on the use of quicklime, in th^ 
 fourth paragraph of the next article. 
 
 2. Mild Lime, powdered unburnt limestone, marles, and 
 chalks, have no solvent action upon animal or vegetable re- 
 mains : on the contrary, they prevent the too rapid composition 
 of substances already dissqlved ; and they have no tendency to 
 form solublejl matters. § Calcareous matter, in some propor*- 
 
 • Elements of Agricultural Chcmistiy, p. 21. 
 
 t Ibid. p. 232. 
 
 i Ibid. p. 21. 
 
 II Ibid. p. 216. 
 
 § That is to say, not in a direct manner : but where there is any mineral or 
 ■saline acid in the staple earth or ordinary manure, tlie radical evil in what is 
 -called .so?/?' lajid, a top drosfsing- of litne, (set abcivcj 1. 1.} ^\-ill nenfralizc tlm 
 
44 MILD LIME AS A MANURE, 
 
 tions, seems to be an essential ingredient in all fertile soils ; ne- 
 cessary perhaps to their proper ttxtui^e, or as a constituent iu 
 the organs of plants.* 
 
 Although lime, when rendered mild by the recovery of the 
 carbonic acid which was expelled in burning the limt- stone, does 
 not undergo any further change in itself by continued exposure 
 to the air, yet when saturated with moisture descending in 
 showers or otherwise conveyed to it, it has the property of at- 
 tracting an additional quantity, or second dose, of carbonic 
 acid : this — not entering into its constitution, but hanging loose- 
 ly about it by a transient association — the mild lime readily 
 parts with to vegetables growing near ; at the same time the 
 bulk of the mild lime is a little lessened by the action of mois- 
 ture dissolving part of its crust. Lime in every state has also 
 the property of attracting volatile oils floating in the air, as well 
 as fluid oils in contact with it. 
 
 The efficacy of a dressing of mild lime is proportioned to 
 the deficiency of calcareous matter in the natural soil. All 
 soils which do not effervesce with acids, are improved by mild 
 lime, and sands more than clays. The rubbish of mortar, on 
 account of the quantity of sand which it contains along with 
 the chalk, is peculiarly fitted to benefit clayey soils. Marie, 
 though the basis of it is mild lime, is to be distinguished from 
 a pure calcareous dressing, because it usually contains the re- 
 mains of some animal matter, with a little clay or peat. 
 
 When a soil which requires an accession of calcareous mat- 
 ter, at the same time contains much vegetable manure, which is 
 already soluble by the ordinary agency of moisture and natural 
 heat, without any ingredient that calls for quicklime, — the cal- 
 careous dressing should consist of chalk, marie, or mild lime .; 
 
 acid matter. Quicklime is more efficacious tlian mild lime for this purpose ; 
 but simple chulk, also marie, applied in large quantities, will correct the evil. 
 These manures, by neutralizini;' tlie acids combined with the mould, qualify 
 the vegetable and other soluble substances also present, to be converted by 
 the influence of the atmosphere and of moisture into nutriment for plants. — . 
 All the experiments yet made render it probable, that the food of plants, as 
 it is taken up from the soil, is imbibed by the extremities of the roots only. 
 Hence, as the extremities of the roots contain no visible opening, we may 
 conclude that the food wliich they imbibe must be in a stale of solution first. 
 And, in fact, the carbonaceous matter, in all active manures, is in such a state of 
 combination as to be soluble in water whenever a beneficial effect is obtained. 
 AH the salts which we can suppose to make part of the food of plants, are so- 
 luble in water. This is the case also with lime, whether it be pure or in the 
 state of a salt : magnesia, and alumina may be rendered so by carbonic acid 
 gas ; and even miiuUe flinty sand may be dissolved in water. We can see, 
 therefore, in general, though we have no precise notions of the veiy combi- 
 nations that are immediately imbibed by plants, that all the substances which 
 form essential parts of their food 7nay be dissolved in water. Sijstem of Che- 
 misinj, by Thomas Tliomson, M. D. F. R. S. E. Vol. V. p. 376. 3d. edit. Edin. 
 1807. 
 
 • Elements of Agricultural Chemistry, p. 21. Compare with " Practical 
 Gardener," p. 601. 
 
UNBURNT LIME AS A MANURE. 45 
 
 and the application of quicklime should be avoided ; as quick- 
 lime is disposed to unite with the soluble matter of dead jjlants, 
 destitute of woody fibre, before the latter can have benefited 
 the soil, and thus forms a compound insoluble in water. Quick- 
 lime also, while it purifies, diminishes the strength of animal 
 manures ; it should never be applied with these, unless they 
 are too rich, or for the purpose of preventing noxious effluvia, 
 as in the cases of reducing carrion, or qualifying night-soil, af- 
 terwards mentioned : it is calculated to render soft animal ma- 
 nures less nutritive, and to make oily matters insoluble.* 
 
 Quicklime is also injurious when mixed with any common 
 dung, and tends to render the extractive matter insoluble. Fur- 
 ther, when it unities with oily matters, it produces a soap not 
 easily dissolved, like the less tenaceous compound formed by 
 mild lime. 
 
 Limestones that contain flinty or clayey particles, are not so 
 good as others for burning into lime j but they possess no nox- 
 ious quality. 
 
 Bituminous limestones contain a fraction of coally matter, 
 never amounting to one-twentieth. They make good lime : and 
 the coally matter, so far from injuring land, may, under favour- 
 able circumstances, be converted into food for plants. 
 
 Nothing yet has been said in regard to unburnt limestone. 
 In a district where limestone is plentiful, and fuel scarce, a far- 
 mer, anxious to leave no local resource neglected, might natu- 
 rally fall upon the idea that lime, in an uncalcined state, if re- 
 duced to powder, or ground into small calcareous gravel, would 
 be beneficially applied as a manure where mild lime would be 
 serviceable, without being aware that the same practice had 
 been already partially tried. 
 
 The first attempt to convert unburnt limestone into a manure, 
 was made by Lord Kames : no account, however, is known to 
 be extant, from which we can learn how far it succeeded ; and 
 the trial must be supposed to have proved abortive, if made 
 upon moss or moorish lands, which, owing to the great quan 
 tity of imperfectly decomposed vegetable remains imbedded in 
 them, cannot possibly be benefited by any substaiice possessing 
 less activity in destruction than caustic lime. 
 
 Many years afterwards a large machine was erected in the 
 county of Perth, which was furnished by three pounding-instru- 
 ments of iron from the Carron Foundry, worked by a stream 
 of water, for breaking unburnt lime into small rubble. This 
 machine was unfortunately carried away by a flood before 
 the eff"ects of such lime as a manure could be decisively appre- 
 ciated ; but as far as the intervening time allowed of experi- 
 
 • Elements of Agricultural Cliemistry, p. 218 
 
46 TIME or LAYING ON MANURE. 
 
 ments, the conclusions were favourable. Much of it had been 
 expended o.) a farm of Colonel Alexander Kobertson. 
 
 As the thewry of the thing, those who are sanguine in recom- 
 mendiiig a fartaer trial of it, suppose that unburnt limestone 
 must ue more powerful in its effects than mild lime, which has 
 gOi.e through the double process of burning and conversion into 
 chalk. Any given quantity of raw limestone, say they, — a bush- 
 el, tor uistance. — contains twice as much calcareous earth as 
 the same bulk of slaked lime. Further, it is commonly ima- 
 gined by persons who have used both kinds, without making' 
 any accurate experiments, that the effects of the raw limestone 
 are slow, but more lasting ; of the calcined limestone, more ex- 
 peditious, but not so permanent. But they seem to overlook 
 the true grounds of comparison. Limestone, in burning, loses, 
 it is true, considerably in weight by the carbonic acid gas which 
 is expelled : Lime, in passing from a caustic to a mild state, 
 recovers this gas from the atmosphere ; but it does not regain 
 the qualities of hardness and cohesion ; and differs from what 
 it originally was, as powdered chalk from marble, or nearly so, 
 according to the texture of the. fossil burnt. Unburnt lime- 
 stone, therefore, has neither the solvent activity of quicklime, — •- 
 nor the absorbing power of chalk, — nor the minute division ol 
 mild lime mixed with eai'th, while an impalpable powder. 
 
 ihie of laying on Lhne. — Nothing has been said of the 
 stages in husbandry at which the application of lime is most 
 beneficially mad^ : because this is quite distinct from an inquiry 
 into the principles on which the good or ill effect of lime on 
 different soils can be accounted for. Indeed it depends on con- 
 siderations which the gardener and agriculturist, each alone in 
 his own province, is qualified to weigh, from an intimate know- 
 ledge of their respective lands, and by the professional expe- 
 rience gained in raising the intended crops. Nevertheless, in 
 the valuable collection of Papers which conveys the gathered 
 wisdom of the school of Scottish agriculture, some information 
 occurs on this subject, which it may be useful to disseminate, 
 as marking the general lines of a successful practice. 
 
 " Li the best cultivated counties, lime is now most generally 
 laid on finely pulverized land, while under a fallow, or imme- 
 diately after being sown with turnips. In the latter case, the 
 lime is uniformlv mild ; in the former, quicklime, as pernicious 
 to vegetation, may be beneficial in destroying weeds. Sometimes 
 mild lime is applied in the spring to land, and harrowed in with 
 gr'.ss-seeds, instead of being covered with the plough; and under 
 this management, a minute quantity has produced a striking and 
 permanent improvement in some of the hiil pastures of the south- 
 eastern counties. Its effects are yet perspicuous, after the lapse 
 of nearly half a century. In some places, lime is spread on grass 
 
MAGNESIA. PHOSPUATE OP LIME. 4T 
 
 land, a year or more before it is brought under the plough ; by 
 which the pasture in the first instance, and the cultivated crops 
 subsequently, are found to be greatly benefited. But in v^hat- 
 ever manner this powerful stimulant is applied, the soil is never 
 exhausted afterwards by a cuccession of grain-bearing crops, a 
 justly exploded practice, which has reduced some naturally fer- 
 tile tracts to a state of almost irremediable sterility."* 
 
 3. Magnesia in a caustic state (burnt magnesian stone) is 
 pernicious to vegetation: mild magnesia is in no respect hurt-- 
 ful, provided there is a deficiency of calcareous matter in the 
 soil. Caustic magnesia, applied to lands charged highly with 
 rich nianure, in a proportion not exceeding one-hfth of the ani- 
 mal or vegetable remains, is speedily rendered mild by the car- 
 bonic acid with which it is supplied, as the nianure decomposes : 
 but it should never be thrown on land where a portion of quick- 
 lime already occupies the surface; because, while the quicklime 
 is becoming mild by its readier attraction for carbonic acid, the 
 magnesia retains its caustic property, and acts as a poison to 
 most plants. Caustic magnesia will destroy woody fibre the 
 same as quicklime; and in conabination with strong peat, assists 
 in forming a manure. If the peat equal one-fourth of the 
 weight of the soil, and the magnesia do not exceed j^jth, the 
 proportion may be considered as safe. Where lands have been 
 injured by too large a quantity of magnesian lime, peat will be 
 an efficient remedy. See also above, 1. Lime as a Solvent, 
 Magnesian limestones are usually coloured brown, blue, or 
 pale yellow : they are found in the counties of Somerset, Lei- 
 cester, Derby, Salop, Durham, Northumberland, and York : 
 they are abundant in many parts of Ireland. f 
 
 4. Phosphate of Lime. — This is a compound of phosphoric 
 acid and lime, one proportion of each ; it is insoluble in pure 
 water, but soluble in water containing any acid matter. It 
 forms the greatest part of calcined bones. It exists in most 
 excrementitious substances ; and is found both in the straw and 
 grain of wheat, barley, oats, and rye ; and likewise in beans, 
 peas, and tares. In some places in these islands, it exists in a 
 native state, but in very small quantities ; it is generally con- 
 veyed to the land by the medium of other manure; and is pro- 
 bably necessary to corn crops, and other white crops.:[: In soft 
 peats, or other lands which contain an excess of vegetable mat- 
 ter, phosphate of lime is one of the most serviceable manures. 
 See IX. 6. : 
 
 5. Gypsum, Selenite, or Sulphate of Lime, is found na- 
 tive at Shotover Hill, Oxfordshire ; and abounds in many other 
 parts of England. Natural gypsum commonly consists of wa- 
 
 * Tteneral Report of the Agriculture of Scotland, &c. 
 f Elements of Agricultural Chemlstrj', pp. 220, 221. 
 T Ibid. p. 228. 
 
4S GYPSUM AS A MANURE. 
 
 ter, sulphuric acid and lime ; 22 parts of water, 46 of sulphuric 
 acid, and 32 of lime. Wh.-n the water is expelled by heat, the 
 other constituents keep their proportion unaltered. As a ma- 
 nure, it is the subject of much difference of opinion. It may 
 unravel some perplexities, and conduce to a fair estimate, it we 
 treat of it under the four following heads : 
 
 I. Theory of its Operation. — Gypsum meets in few soils any 
 thing which can decompose it; and while its elements remain 
 fixed, it neither assists the putrefaction of animal remains, nor 
 the decomposition of manure. The ashes of particular sorts 
 of peat contain a considerable quantity of gypsum ; some kinds, 
 a- third part : and such ashes have been applied with good ef- 
 fect as a top dressing for cultivated grasses. In correspondence 
 with this, the ashes of sainfoin, clover, and rye-grass, afford 
 considerable proportions of gypsum : but only a very minute 
 quantity of it is found in barley, wheat and the turnip. The 
 reason why the artificial mixture of gypsum with soils is not ge- 
 nerally effice^ceous, is probably, because most cultivated soils 
 contain sufficient quantities of it for the use of the grasses, and 
 an excess of it above what other crops absorb in their growth. 
 Gypsum is contained in stable dung, and in the dung of all cat- 
 tle fed on grass ; and it is not taken up in corn crops, or crops 
 of pulse, and in very small quantities in turnip crops. 
 
 It is possible that lands which have ceased to bear good crops 
 ai cultivated grass, maybe restored by a dressing of gypsum.* 
 As to a general standard for the application of gypsum, those 
 plants seem most benefited by its application which always af- 
 ford it on analysis : such as lucerne, clover, and most of the 
 artiffcial grasses : But where the soil already contains a sufficient 
 quantity of this substance for the use of the grasses, its appli- 
 cation even on pasture cannot be advantageous : for plants re- 
 quire only a determinate quantity of manure ; an excess may 
 be detrimental, and cannot be useful. f 
 
 It has lately been asserted, on the authority of a gentleman resi- 
 dent at Pittsburgh, in Pennsylvania, that gypsum is only useful 
 as a manure in those parts of the United States that are distant 
 from the sea not less than eighty miles. On the hypothesis that 
 sea-air destroys the fertilizing principle in gvpsum, Mr. R. 
 Bake^^^ell, a correspondent of the Monthly Magazine,:}: pro- 
 ceeds to account for its failure as a manure in so many parts of 
 England. It is enough to dispel this opinion to name the county 
 of Kent, as the place where it has most fully succeeded. 
 
 Sir H. Davy in directing our attention to the constituents of 
 this manure, the composition of the soil, and the nature of the 
 plant, has contributed material aids for judging when to apply 
 
 • Elements of Agricultural Chemisty, p. 224. 
 
 t Ibid, 19 
 
 t For October, 1815. 
 
GYPStJM AS A MANURE. 49 
 
 k :'— But perhaps he has not adverted sufficiently to the inimita- 
 ble chemistry of Nature, by which she may disengage the ele- 
 ments of gypsum when buried in a suitable soil, and enable par- 
 ticular plants to extract them in a simpler form. It therefore 
 becomes important to recollect, that the sulphuric acid^ which 
 lodges in gypsum in a solid state, can be resolved into — sulphur' 
 oils acid gas^ about 40 parts ; and oxygen, 60 parts ; and that 
 when the water suspended with the two gases is dissipated, thfe 
 proportions will be nearly, 
 
 Condensible into sulphur ----- 16 parts. 
 
 Oxygen ___.._ 54 
 
 Water ------...-.20 
 
 100 
 
 Now, instead of confining the possible benefit to such plants as 
 afford gypsum in an unaltered state, may we not conclude that a 
 large number of vegetables, constituted to reject the calcareous 
 base altogether, may appropriate some modification of the other 
 elements ? " The saline compounds (as professor Davy in 
 another place notices) contained in plants, or afforded by their 
 ashes, are very numerous. The sidphuric acid^ combined with 
 potassa, or sulphate of potassa, is one of the most usual. Com- 
 pounds of the nitric, muriatic, sidphuric^ and phosphoric acids, 
 exist in the sap of most plants." In analogy with some late ex- 
 periments of DeSaussure,we may further suppose that sulphuric 
 acid, diluted with water by the chemistry of Nature, may be 
 instrumental in converting the starch of plants into sugar. " As 
 starch boiled in water with sulphuric acid, and thereby changed 
 into sugar, increases in weight without uniting with any sul- 
 phuric acid or gas, or without forming any gas, we are under the 
 necessity of ascribing the change solely to the fixation of water. 
 Hence we must conclude, that starch-sugar is nothing else than a 
 combination of starch with water in a solid state. The sul- 
 phuric acid is neither decomposed, nor united to the starch as 
 a constituent ; nevertheless it is likewise found that long boiling 
 in pure water does not convert the starch into sugar."* This 
 fact opens a large field for rational speculation qn the physiology 
 of vegetables ; as it renders it possible that some of the mineral 
 acids in the sap of plants, after acting chemically^ on the juices 
 concocted into pulp, may be thrown out unchanged : they may al- 
 ter the flavour without entering into the essence of the fruit. 
 
 Another step in the process of conversion brings us to pure 
 sulphur. Some plants yield this on analysis. Seeds, sown by 
 way of experiment on nothing but this mineral, have produced 
 
 * See a Translation of the original Paper in Jminls of Philosophy for De- 
 cember 1815. (No. XXXVI. pp. 425, 426.) 
 
 G 
 
50 GYPSUM AS A MANURE. 
 
 healthy plants ; and many soils, which nature has inr.pregnatetl. 
 with sulphur, are highly fertile. 
 
 The peats or loams on which gypsum has been most success- 
 ful, niav contain vegetable acids calculated to decompose it. It 
 is true that the means by which human art can at present sepa- 
 rate its elements are very limited. It is decomposed, 1. by the 
 oxalic acid ; 2. by carbonates of potash ; 3. by carbonate of stron- 
 tium ; 4. by muriates of barytes. The second and third solvents 
 are only mentioned to be dismissed, as unlikely to be of .ny use 
 in agriculture : the carbonate of lime generated by the second, 
 being less soluble in water than the sulphate ; and chalk, when 
 wanted, can be had at a cheaper rate. The third, carbonate of 
 strontian, is a newly-discovered earth, of rare occurrence. As 
 to the compound produced by the fourth, sulphate of barytes is 
 perfectly insoluble in water : and it is a reasonable suspicion th'at 
 it would be pernicious to vegetable life. 
 
 To recur to oxalic acid, the first-mentioned solvent. This 
 is naturally present in wood-sorrel, and is procured artificially 
 by the action of nitric acid upon sugar, and several other vege- 
 table substances. Peat-moss, in an unreclaimed state, usually 
 abounds with oxalic acid : hence there is a mutual action be- 
 tween that sort of peat and gypsum. Perhaps such a compound 
 might be cheaply imitated, by mixing vegetable mould and wood- 
 ashes, urine and gypsum ; or short muck, old cow-dung, sea- 
 Wi-ed, and gvpsum, — substituting, where sea-weed cannot be 
 oonv.ned, soap-lye ; or bleacher's lees ; or salterns refuse, vege- 
 c: I :' ashes, and water. 
 
 It may be worth' while also to try, whether in those cases 
 vhcre quicklime would form an insoluble compound, or dimin- 
 ish the nutritive richness of a compost, gypsum may not be a 
 apital ingredient ; for instance, with some of the following sub- 
 stances t oiiif vrtitters ; — animaLncids; — all artitnahrtamtres^ par- 
 ticularlv such ms contain allnoffen, (one element in the white of 
 eg}j;s is sulphur;) — the common dung- of cattle. 
 
 Furtliur, as mild lime and gypsum seem to be as unlike each 
 other as two substances with the same base can well be, it may 
 be of practical benefit to compare their effects in various com- 
 posts of the same strength. 
 
 To clone this theoretical part, sulphuric acid has a great at- 
 traction for water, and may be useful in a soil in summer. Where 
 the sulphur cannot be decomposed, it may diminish the cold- 
 .ness ot soii'.e lands. Gypsum may be offensive to delicate aphides 
 by the same impregnation; and it may kill some hardy insects 
 by setting into a hard crust upon them. 
 
 In addition to the common case of land being already satura- 
 ted with gypsum or lime, are there any descriptions of soil on 
 which decomposed gypsum might have a liad effect? 1. Would 
 it not deteriorate a soil containing particles of iron ? This may 
 
GYPSUM AS A MANUllE. 51 
 
 be put as a caution ; for sulphate of iron is pernicious to vege- 
 tation ; but as lime is the antidote to that vice in a soil, decom- 
 posed gypsum seems, even in this case, to contain its own re- 
 medy, unless the proportion of lime be thought too low. 2* 
 Might not the sulphuric acid hurt the texture of a soil almost 
 livhoUy composed of pure clay ? Sulphate of alumina is not 
 . baneful to plants as a salt, though, as a mineral earthy compound, 
 it is not the most tractable under tillage : but here again lime is 
 pi'esent, to prevent its formation, or to dissolve it. 
 
 II. Experience of it abroad. — It is about half a century since 
 gypsum was discovered to have in Pennsylvania almost a 
 magical influence on the growth of red clover; and it is there 
 held in rising estimation. The Pennsylvanian farmers seem to 
 have derived from Europe the first suggestions for applying this 
 manure to artificial grasses. M. Gilbert, from whom a quota- 
 tion is given in Sect, iv., states the practice to have long pre- 
 vailed in France with signal success. In Germany, Mr. Mayer, 
 a clergyman, discovered the use of gypsum as a manure about 
 the year 1768 ; and in Voghtland, in Saxony, gypsum-earth is 
 said to have converted several barren tracts into fruitful fields. 
 The agriculture of Switzerland has also reaped much benefit 
 from the same resource. 
 
 III. Experience of it in this Island. — Perhaps it has not yet 
 received a fair trial here ; but as far as experiments in different 
 counties of England and Scotland are reported, the mass of evi- 
 dence is against it. 
 
 [As the FinsT ExPEniMEUT of Arthur Young relates to a particular point in 
 ihe " Method of Pi'cparing and Applying it," it is given under that head.] 
 
 SECOND EXPERIMENT by the EDITOR of ANN. AGRIC. 
 ^Marked five square Rods of Clover on a good Turnip Loam -with a gravelly bot' 
 toiii, luorth lOs. an acre, in JYIcirch, 1791. 
 "No. 1. Sprinkled with one quart of gypsum. 
 
 2. Two quaris. 
 
 3. Three. 
 
 4. Four. 
 
 5. Five quarts of wood a.shes. 
 
 '* Nos. 1 and 2 were equal, and ratlier superionr to any of tlie rest. No. 5. 
 was the worst. The clover manured (compared with tlie adjoining land that 
 had no manure) was not only considerably higher, but thicker, of a deeper and 
 more luxuriant colour, and of a bi'oader leaf. 
 
 " One quart to a rod, is five bushels to an acre. I am confident that neither 
 •iuch a quantity of night-soil, pig-dung, peat-ashes, nor any other manure with 
 which I am acquainted would liave had an equal effect. The result of this ex- 
 periment is therefore quite contrary to that of last year.* A. Y." 
 
 EXPERIMENT by JOHN ALLEN, Esq. on four square Rods, First Year's 
 
 clean Clover. 
 Nos. 1 and 4. No manure. 
 No. 2. Four quarts of sifted cinder-ash which had never been exposed tp 
 
 the atmosphei'e. 
 No. 3. One quart of gypsum. 
 
 * Annals of Agriculture, Vol. XVI. p. 184. ' 
 
'52 GYPSUM AS A MANURE. 
 
 When the clover was in full head, all^being mown, the produce of Nos. 1 
 and 4. averaged 38 /6s. 6 oz. each. , 
 
 No. 2. weighed 50 lbs. 
 No. 3. 54 i lbs.*- 
 
 Another gentleman, Mr. R. Procter Anderdon, of Henlade, 
 Somerset, atter detailing some trials, says, — " Hence I conclude, 
 s's tar as my experiments go, that on many plants, or on many 
 soils, gypsum powder will have no effect ; but that it has an ef- 
 fect on old clover, on a loamy soil ; and that a greater effect may 
 be reasonably expected from it, when applied to younger plants of 
 the same sort."f 
 
 From a subsequent Letter of the same Correspondent, it 
 seems greatly to promote the growth of Chicory, and to be de- 
 structive to the slug. 
 
 A farmer, near Epping, in ITQl, found it greatly to increase 
 the returns from a sowing of oats. 
 
 The extensive experiments made by a Kentish farmer, in the 
 years 1792, 1793, and 1794, are reported in the Bath Papers., 
 vol. VIII. The first states generally that they were chiefly up- 
 on " light loams and poor calcareous soils, especially of the 
 chalky kind.'' It is therefore very important that the following 
 observation, which occurs in detailing a particular experiment, 
 should have a conspicuous and prominent place. " A light 
 loamy earth to the depth of three feet on chalk, produced much 
 better crops, than a shallow surface on chalk, both having been 
 manured with gypsum." The plants were chieHy sainfoin, cow- 
 grass, and Dutch clover ; and repeated trials were attended with 
 favourable results. / 
 
 To these might be opposed many instances of the failure of 
 gypsum as a manure, in various parts of England, even when 
 applied to grass-lands : but the failures uniformly consist, not 
 in any pernicious effect, but in the want of any superiouj;, re- 
 turns, compared with unmanured lands of the same quality. 
 
 Whether it is that in North Britain the farmers find it more 
 profitable to pare off peat, and use it as a compost for lands un- 
 der tillage, than to attempt the reclaiming of entire beds of 
 soft peat by immediate cultivation,— or whether they have 
 cheaper top-dressings, — the sum' of their experience in regard 
 to gypsum, is expressed in the following sweeping conclusion : 
 " Gypsum has not hitherto been attended with any success in 
 Scotland.":]: As to grass-lands not abounding in vegetable re- 
 mains, what has been stated under head i. makes it less surpri- 
 sing that a dry powder, so hard to decompose, should not have 
 produced any effect corresponding to its reputation in Ame- 
 rica. 
 
 • Annals of Agriculture, vol. XVI. 303. 
 t Ibid. vol. XVII. p. 297. . • 
 
 k General Report of the Agricultural State on Scotland, vol. II. p. 537, 
 
GYPSUM AS A MANURE. 53 
 
 IV. Method of preparing and applying it. — Even those wri- 
 ters who maintain that there is nothing like gypsum, pointedly 
 differ in their instructions for preparing and applying it. One 
 in the opposite hemisphere says : " The spring oi the year has 
 been esteemed the best season for sowing it; but Ihave sown 
 it in March, April, May, June, July, August ; and 1 know no 
 difference in its effect. You will observe, it is only a top ma- 
 nure, therefore must be sown on a sward of grass : it is parti- 
 cularly good for white and red clover. It may be broken by- 
 hand, and afterwards sifted ; but we stamp it, and afterwards 
 pass it through our mill-stones : it must not be calcined"* 
 
 " Six bushels to the acre I use, and it is preferable 
 
 to fifty loads of the best dung. This you must think extrava-* 
 gant ; it is so, and yet true."f 
 
 M. Gilbert, author of a Treatise on Artificial Grasses^ pub- 
 lished in France,:]: says, that " it produces the same effect whe- 
 ther IT IS CALCINED OR ROUGH, if it is but powdercd ; that 
 six bushels, Paris measure, manure very well an acre for a year; 
 and that half that quantity does for the two following years. 
 The only thing to be attended to, is, not to sprinkle this manure 
 before the seeds which are mixed in the herbage are near ripe : 
 if sowed sooner, it makes the trefoil grow so fast as to smother 
 
 the grass with which it is mixed It only produces^ 
 
 beneficial effects when sowed after or before rain ; sowed on dry- 
 land which continues such, its effects are nothing." 
 
 As to CALCINING : It is not likely to make any difference, be- 
 cause the sulphuric acid in gypsum cannot be expelled by the 
 most violent heat of the furnace ; and an experiment of Arthur 
 Young§ countenances the assertion, that the effects of gypsum 
 are the same, whether calcined or rough. It is thus stated ; 
 
 " Spots -were staked out on an upland meatlo-,a of clover. 
 
 No^l. A perch iincalcined. The grass weighed, green, 112 lbs, 
 No. 2. Calcined. 114 lbs. 
 No. 3. No manure. 113 lbs." 
 
 The produce is vincommonly great ; but the equal success ol 
 the unmanured piece makes this experiment a comparative 
 failure. 
 
 The American farmers employ it upon netu ground., and 
 strew it upon the surface. In reclaiming a peat not already dis- 
 posed to form sulphate of lime, it may qualify an excess oi^oft 
 vegetable matter very beneficially. It does not follow, however, 
 that on lands differently circumstanced, particularly upland 
 
 • Extract of a Letter from Philadelphia, dated Sept. 16, 178S, A/inals of 
 Agriculture, vol. XV. p. 109, 
 t Ibid. June 1, 1790, p. 110. 
 
 t Reviewed in J/inals of Jlgricnlturp, vol. XV. p. 444. 
 ^ Annals ^f Agriculture, vol. XIV, p. 319. 
 
54 ON CLAY-BURNINCJ. 
 
 pastures, which aecm to be worn out, the same mode of appli- 
 cation ought to be adhered to ; and it a restorative is sought in 
 gypsum, the history both of its successes and its faikires, would 
 recommend a compost containing peat, or some imitation of it. 
 This will be a fair test of what it can effect. 
 
 6. Burnt Clay. — Of late, very flattering reports have been 
 circulated of the practice of burning clay into ashes, for a top 
 dressing. It is not a recent invention : for very pai-ticular in- 
 structions for doing it are given in a small Treatise, published 
 near a century ago.* Revived lately in Scotland, the process, 
 described in a letter by Mr. Craig, has excited much attention, 
 and induced many spirited agriculturists, in various parts of the 
 island, to adopt it on a large scale. The expectations from it 
 are sanguine ; although the experience had of it is not yet ex- 
 tensive enough to form a ground of recommending it for gene- 
 ral application, it is called " Burning Clay for Manure : yet, as 
 the torrefied powder is not valued for any vegetable ashes suppo- 
 sed to be contained in it, as in the common practice of paring and 
 burning, but is simply to operate as burnt earth, it were more 
 correct to modify the term to " Burning Clay to improve the Tex- 
 ture of the Soil." This is not a verbal distinction, but a practical 
 difference. If attention to it should much contract the field for the 
 operation, it may prevent many disappointments. Thus, suppose 
 the agriculturist is induced, from his system of farming, to cul- 
 tivate turnips on a clayey soil, not well adapted to their gi-owth, 
 it is plain that the ashes of burnt clay, copiously distributed over 
 the surface, would immediately consult the ^habits of the plant, 
 by dividing a tenacious, and rendering drier a humid soil ; and 
 thus, without supposing the burnt clay to act as a manure, the 
 texture of the staple would receive a permanent improvement. 
 On the other hand, if on a soil not rich in the common basis of ve- 
 getables, and which is to be planted with any of the exhausting 
 culmiferous crops, or other crops dependent on a generous soil, 
 the panacea of mere burnt earth is resorted to, as a substitute 
 for the long tried proportions of consumable manure, the result 
 of such an ill-timed application of fire must be disappointment. 
 
 Indeed the operation of burning clay for ashes is so tedious 
 and expensive, that even where the circumstances of the land 
 demand such an improvement, the outlay would overwhelm the 
 farmer — unless he intermit the practice during those stages of 
 rotation in which he can raise beans, and other crops fit for clay 
 
 * Tlie Practical Farmer ; or, the Hertfordshire Jliisbandman. See a Let Icr in tlie 
 Farmer's Magazine, No. LXllI. with ilie si.tynivtiire " J.-G. F." It is also men- 
 tioned in The Coitntrii Gentletna/i'ii Conipanioii, b_v Stejjhen Switzer, Gardener. 
 (London, 8vo. 1732) 'I'liis latter work slates, lliat the Earl of Halifax was 
 the inventor of this resource : and it gives several letters, written in 1730 
 and 1731, attesting- its success in several ]5arts of Kiii^-land; with accounts from 
 Scotland that it had answered better than lime or dung !— but was found too 
 expensive. 
 
ON CLAY-BUllNING. 55 
 
 oils, by easier modes of tillage. If, however, he is satisfied 
 to prepare land, by this practice, for the green crop, or other 
 stage of a rotation which most requires it, and is attentive at 
 other times to keep up the vegetable strength of the staple by 
 soluble manures adapted to repair the exhaustion of preceding- 
 harvests, and to meet the appetite of the expected crop, the 
 texture of the soil will be gradually improved, while the dan- 
 ger of relying upon burnt earth as a manure will be avoided. 
 If the surface burnt is a peat, or moss, or contains the roots or 
 other remains of plants, the ashes may be truly a manure ; but 
 then the principle and its application are assimilated to the 
 practice of paring and burning tuif, and the useful commerce 
 in peat ashes ; neither of which is a novelty. So a marl, fraught 
 with animal remains, is decidedly a manure. 
 
 The clay may. be either burnt in heaps, or in kilns. For this 
 purpose, it is dug or pared off in shallow spits, ab-.ut four in- 
 ches thick. Two layers of these are commonly taken. Whe- 
 ther any part of the subsoil should or should not be also dug 
 up, depends upon its composition. See above, Sect. IV. It 
 accelerates the process of ignition to set the spitfuls first to dry, 
 either separately or in open piles. The kiln may be fired with 
 furze, wood, cinders, coal, or any combustible refuse. As to 
 the quantity of ashes to be applied, the Hertfordshire Husband- 
 man says, — " About forty bushels, sown on an acre by the hand, 
 out of the seed-cot, and harrowed in with barley and grass 
 seeds, does vast service." The Scottish agriculturists assign 
 from twenty to twenty-five cubic yards per acre, as a dressing 
 for turnips. 
 
 When kilns are used, limestone may be burnt with the clay. 
 
 If this practice be combined with that of burning with lime 
 instead of fire, the expense will be lessened, and a manure of 
 better composition obtained. It may be acceptable to describe 
 a good method of doing both together.* 
 
 Pare off the sods, or turf, and surface clay, with the skim- 
 coulter plough, or other convenient instrument, and dry the 
 parings ready for burning. Get quicklime fresh from the kiln 
 in the following proportion : having marked out a base for the 
 pile, for every square superficial yard, three Winchester bush- 
 els of lime ; or for a mound seven yards in length, three yards 
 :md a half in breadth, 72 bushels. In building, begin with a 
 layer of dry parings, six inches in height ; on which spread half 
 the lime intended to be used, about five inches thick, mixing sods 
 with it; then a covering of eight inches of sods ; on this the other 
 half of the lime is spread, and covered a foot thick ; the height 
 of the mound at this stage being about ayard. Mr. Curwen deems 
 it better to suffer it to ignite of itself, than to effect the combustion 
 
 * The following- is derived from the Letter of Mr. Curwen, of Workington- 
 Hall, to Mr. Dempster, of Diinichen, publi.shed, by permission, in the Farmer'^ 
 Magazinp, No. LXJV. p. 411. 
 
5(5 AllNERAL SUBSTANCES. 
 
 by applying water. In twenty-four hours it will take fire. When 
 the fire is fairly kindled, fresh sods must be applied. Mr. C. 
 recommends obtaining a suflicient quantity of ashes, before any 
 clay is put upon the mounds. The lire naturally rises to the 
 top. It takes less time in piling, and effects more work, to draw 
 down the ashes from the top, and not carry the mound higher 
 than six feet. The clay if not sufficiently burnt is lumpy, and 
 unlractable under tillage : on the other hand, Mr. C. regards 
 calcined ashes as of no value ; but they ought certainly to be burnt 
 to a powdery state, or until they will fall to powder from a slight 
 stroke ; and it does not appear that the calcination of any earth 
 lessens its absorbmg power. The finer clav-ashcs arc, the great- 
 er is their capacity of absorption from the atmosphere. 
 
 Some idea may be formed of the spirit with which Mr. C. 
 lias taken up the trial of this system of surface-soil and clay- 
 burning, when he says, " I have just completed paring twenty- 
 six acres of clover lea of the second crop, which I intended 
 next year for turnips. The sods were well broken with the 
 harrows, which freed them of the greatest part of the mould. 
 The residue was burnt, and has afforded me above a thousand 
 single-horse carts of ashes. There are twelve mounds with se- 
 venty-two Winchester bushels of lime each I have ma- 
 nufactured for use this season, two thousand single carts of 
 ashes." 
 
 On lands thus manured, while turnips and clover have, in the 
 most favourable cases, surpassed expectation, wheat has fallen 
 below it. At present the balance of experience from the recent 
 trials seems to have this inclination : the advantage of bunnng 
 clay alone is questionable, as a measure of general applica- 
 tion ; and unless vegetable matter or lime is burnt with it, the 
 benefit will seldom repay the expense. When clay has been 
 burnt alone, dung, or other manure containing vegetable nutri- 
 ment, should be spread with it, especially in preparing land for 
 an exhausting crop. 
 
 Many discoveries in tillage fall into disrepute by being ap- 
 plied without regard to local circumstances, or by being con- 
 tinued after a suflicient change has been effected in the original 
 constitution of the soil. Burnt clay can only be what physicians 
 would call a topic:vl remedy. 
 
 VlII. Bij introducing Mineral or Saline Elements as Ma- 
 nures. — Mineral substances are more or less contained in 
 decayed animal or vegetable matters. When these sub- 
 stances have been extracted in a pure state, by a chemical pro- 
 cess, they are in general too expensive and too useful in the arts 
 or* in the ordinary affairs of life, to be applied as manures: on 
 which account the following experiments will serve rather to 
 slicw the principle or cause of a fertilizing, or contrary effect, 
 from the gross matters in which they are found, than for the 
 purpose of expending the pure extract on any soil, as in the ex- 
 
DIFFERENT SALTS COMPARED. 57 
 
 jvcriments : on the other hand, it will appear, from some of the 
 details under this article, vvhy'an earthy mass, or heap ol reluse 
 matter, containing a particular chemical sui)stance,may he bene- 
 ficial, — while that substance in a pure state is pernicious. 
 
 1. Common Salt, or Muriaie or Soda. — The Mineral 
 Alkali of Soda is tlie basis oi' Marine Salt. " When common 
 salt acts as a manure, it is probably l)y enterinjj into the com- 
 position of the plant in the same manner as gypsum, phosphate 
 of lime, and the alkalies. It has been proved to have been 
 sometimes useful in small quantities. It is likewise oftensiveto 
 insects. Some persons have argued against the employment ot 
 it, Ijecause, when used in Inri^e quantities, it either does no 
 good, or r(;nd(;rs the land sterile ; but this is not a cause lor en- 
 tirely rejecting it. In Cornwall, the n fuse salt from the large 
 ■works of dry-salters — which, it is to be reme>Ml)ered, contains 
 some of the oil and scales or other parts of the juices and skins 
 of fish — has long been known as an admirable manure. But 
 as latent muriate of soda is one of the constituents m almost 
 every kind of animal and vegetable manure, the cultivated lands 
 of these islands may be supposed to contain, in general, a sufTi- 
 cient quantity for the purposes of vegetation, (not to mention 
 that the surrounding sea must have an effect on the air and soil 
 to a considerable distance inland ;) so that a direct supply of it 
 to the soil may be found, in most cases, not only useless but in- 
 jurious.* In the water given to plants which are natives of the 
 sea-coast, a minute infusion of common salt would consult the 
 natural circumstances of that description of vegetables : indeed 
 they languish without it.f 
 
 2. Comparative Effect or oifferknt Salts. — Profes- 
 sor Davy confirms and illustrates the above and affords a general 
 principle for the solution of contradictory results under altered 
 circumstances, by an experiment on the effect of different salts 
 conveyed in water to the roots of plants. 
 
 The subjects of trial were separate spots in a garden, on 
 which grass and corn were growing. The soil of the place was 
 a light sand, — of which 100 parts contained 60 of flinty sand, 
 24 of finely divided earth or chemical elements of earth, and 
 j 16 of vegetable matter; and of the whole, less than one part in 
 100 was saline matter, principally common salt. The saline 
 substances tried were super -carhonutc of potassa^ (crystals of 
 soda,) sulphate of potassa^ (vitriolated tartar,) acetate ofpotassa^ 
 (foliated earth of tartar,) nitrate of potassa^ (prismatic nitre,) 
 and muriate of potansa ; sulphate of soda^ (glauber's salt or vi- 
 triol of soda ;) sulphate^ nitrate^ muriate and carbonate of am- 
 monia. The quantities applied were two ounces to each spot 
 
 • Elements of Agricultural Chemistry, p. 230, 
 
 t System of Chenmtry, by Thomas Thoniso/i, M.D. F.U.S.R, vol. V. p. 364. 
 od edit. Edlnburgli. 
 
 H 
 
58i SOOT. — COAL-ASHES. 
 
 twice a week. In all cases wlicrt- Uk quantity equalled j^tfa 
 part ot the water, the eflect was injurious ; i)Ui least so in the 
 instances ot the carbonate, sulphate, and muriate ot ammonia. 
 When the quantities ot the salts were y^tj '^^ ^^^ solution, the 
 effects were different : — i'hen, the plants watered with the solu- 
 tions ot the sulphates grew just in the same manner as similar* 
 plants watered with rain water : Those acted upon by sokuions of 
 nitre; acetate, and super-carbonate ot potassa; and muriate ot" 
 ammonia ; grew rather better ; those treated with the solution of 
 carbonate ot" ammonia grew most luxuriantly of all : The plants 
 watered with the solution of nitrate of ammonia did not grow 
 better than those watered with rain water ; " probably (says Sir 
 H. Daw,) the free acid had a prejudicial effect, and intertered 
 with the result." But if tlu- effect was equal to that ot rain 
 water, there was no proof of a pernicious agency ; the ill effect 
 was mereh'^ negative, and seems rather to have prescribed a 
 slight increase in die quantity dissolved in the water. 
 
 IX. Bij Manuring' with RifuHv Sitbtitanccs not exxrcineti- 
 titioits. — ileaps ot refuse matter, which contain excrementitious 
 substances incidentallv, and l)ut in a small proportion, will be 
 included under this article. 
 
 1. SruKKT andRoa.!) Dirt and the Swkepingsof Houses 
 may be all regarded as composite manures. As they are de- 
 rived from different sulistances, their constitution varies ; but 
 in all cases they refresh and strengthen a soil. Scrapings of 
 roads not clayey are i)eneficial without exception : those from 
 high-roads are enriched in far the greater degree by the drop- 
 pings of cattle. The promiscuous dung which is gradually in- 
 corijorated with the sludge, is so jjerfectl}' reduced by exposure 
 to the weather, that it takes the appearance of e;!J th. The effects 
 of road-drift are in many cases Ijeneficial in a higher degree 
 than the cultivator miglit expect from its known composition : 
 but the greatness of the benefit may ht well accounted for, by 
 considering that the gravel, or slate, or stone, which is ground 
 into earth l)y the i)assing of carriages along a road, is neccssa- 
 rilv virg-in-f(irt/t^ having never been in a state to support vege- 
 tation. Fine road-stuff is ix'tter than dung on pasture land. 
 
 2. Soor is a very jjowerful manure ; its great basis is char- 
 coal, in a state of solubility In' the action of air and water. It 
 contains also salt of ammonia, with a portion of oil. To mix 
 soot witli quicklime is a bad practice ; because much volatile 
 alkali is thus disengaged, without any benefit to the land. This 
 manure requires no preparation ; and is well fitted to be used in 
 a drv state, as a top-dressing (a ])eck to four square poles of 
 land) tiirown in with the seed. It is a good improver of cow- 
 dung and goose-dung ; either of which alone, and in a fresh 
 state, are of little power. I'urther, its alkali tends to make oily 
 particles miscible with water. 
 
 3. CoAL-AsiiES. — It appears from an experiment of Mr. 
 
Coal-water. — bones. — hair, &c. 59 
 
 Wright, afterwards particularly adverted to, that coal-ashes on 
 a plot wht;re barley is to be grown has the same efficacy as hog- 
 dung ; while it is inferior to the dung of sheep, and something 
 better than that of horses. 
 
 4. Coal-Watkr, or the liquor produced by.; the distillation 
 of coal, is said to be a good manure. 
 
 5. WooD-AsHES consist principally of the vegetable alkali 
 •united to carbonic acid : and as this alk;ili is found in almost all 
 plants, it may be an essential constituent in the organs of the 
 greater part. The vegetable alkali has a strong attraction for 
 water. See the comparative efficacy of wood-ashes with that 
 of coal-ashes and the dungs of several kinds of cattle and do- 
 mestic fowls, under X. 6. 
 
 ft. Ca.kbonati: of Ammonia. — The liquor produced in the 
 distillation of coal at the C^as Esta!)lishments, may be recom- 
 mended as a valuable manure on the following accounts. First, 
 it principally contains carbonate of ammonia ; (see the experi- 
 ments by professor Davy already sketched :) secondly, it con- 
 tains also a little sulphur. In the proportion of one gallon to 
 16 or 18 of water, this liquor may be applied to all green crops 
 as a manure, with good effect. When the object is to destroy 
 insects, three gallons only of v/ater should be added to one of 
 the liquor. 
 
 7. Coal Tar. — The tar produced in making carburetted hy^- 
 drogen gas is beneficial as a manure, conveyed in proportion- 
 ate heaps of earth or marie. One gallon of this tar being mix- 
 ed with about a wheelbarrow full of mould or fit earthy materi- 
 als, will form a compost of great activity. This may be either 
 ploughed in or used as a top-dressing, as the nature of the land 
 and crop may render expedient. 
 
 8. Bonks consist of phosphate of lime and decomposable ani- 
 mal matter. Bone powder, bone shavings, and bone ashes, are 
 serviceable where phosphate of lime is to be supplied to a soil. 
 Bone ashes ground to powder will impart a reduced share of 
 benefit to aral)le lands, containing much vegetable matter, and 
 may perhaps enable soft peats to produce wheat ; but powdered 
 bone, in an uncalcined state, is always to be preferred to bone 
 ashes, because the oil and other animal matter with which bones 
 are richly charged has not been dispelled. 
 
 9. Horn is still a more powerful manure than bone, as it con- 
 tains a larger quantity of decomposable animal matter :* it is 
 very durable in its effects on a soil. 
 
 10. Hair, Feathers, and Woollen Rags, are all analo- 
 gous in composition ; they are more nearly allied to horn than 
 to bone ; they contain a great quantity of albumen (a substance 
 similar to white of egg,) gelatine (basis of jelly,) with some, oil.. 
 Woollen rags act powerfully for one year. 
 
 * RIemcnfs of .AjrriOTlfijral Cliemistry, p. t9S. 
 
60 liLEACHUll'S WASTE, &C. 
 
 11. }\EFUSK OF Skin and Le.vTher, accumulating in differ- 
 ent manufactories — such as furriers' clippings, the shavings ■ f the 
 currier, and the offals of the tan-yard, and the glue-maker — form ^ 
 highly useful manures ; any one of which, buried in the soil, 
 operates for a considerable time.* 
 
 12. Bleacher's Waste. — it is usual to cast away the resi- 
 duum of the stills as a worthless article : but surely if some 
 competent person were employed to separate the sulphate of soda 
 from the sulphate of manganese, the former might be turned to 
 a good account. The waste solutions of the oxy-muriatic salts 
 are also convertible into a valuable manure. See the experi- 
 ments of Professor Davy, above. Humboldt, about 1810, dis- 
 covered that a weak solution of such preparations, has the pro- 
 perty of accelerating and enlarging the growth of vegetables. 
 Gardeners whose grounds are in the neighbourhood of bleach- 
 fields, would do well in availing themselves of all the advanta- 
 ges their situation affords them for making experiments on this 
 interesting and important subject.f The waste lees, after boil- 
 ing linen yarn or cloth, may also be used for alkalizing com- 
 posts. 
 
 13. Soaper's Waste has been recommended as a manure, 
 under, the supposition that its efficacy depended upon the differ- 
 ent saline substances which it contains : but the quantity of these 
 is very minute indeed ; its chief ingredients are mild lime and 
 quicklime, either of which, when a supply of calcareous materi- 
 als, or when a caustic solvent is wanted in a soil, may be had at 
 a cheaper rate. 
 
 14. The Fluid, or Dissolved Parts, of Animal Sub- 
 stances, require some preparatory process to fit them for ma- 
 nure. The great object is to blend them with the soil in a pro- 
 per state of minute division. When these have been applied in 
 a rank or unreduced state, bad effects have followed. Perhaps 
 while they retain the combinations of animal matter unchanged^ 
 or not ejitirely broken^ they are ill adapted to promote the func- 
 tions of vegetable life. Thus tallows and oils, received in a crude 
 state by the roots, may clog the pores of the bloated plant, repel 
 dews and aqueous fluids, and obstruct the free communication 
 of the kaves with the atmosphere. 
 
 One mode is, to spread the animal fluid thinly on the land un- 
 der tillage, and previous to putting iji the seed or plants^ to suf- 
 fer the free escape of the volatile particles that will go off by ex- 
 halation. The better mode is to convey animal matter in a com- 
 post of earthy or vegetable materials. 
 
 Blood is a good manure. The Scum taken from the boilers 
 of Sugar-bakers consist principally of bullocks'' blood. 
 
 When sugar-baker's waste has been reduced to the finest state 
 
 • Elements of Agricultural Chemistry, p 199. . 
 
 t Chemical Essays, by Samuel Parkes, F. L. S. London, 1815. vol. IV. jO^ 
 
 160. 
 
OIL AND BLUBBER. 61 
 
 possible, it will still be improper for application as a manure^ 
 until it has been mixed and incorporated with three or four 
 times its bulk of some earthy substance, which may be enriched 
 with a proportion of vegetable mould or desiccated dung. 
 
 Graves also are too rank both for corn and grass, unless con- 
 veyed in a compost of earthy materials ; wood ashes may be 
 profitably added, as having a tendency to divide and correct the 
 particles of tallow. 
 
 Oily substances contain a deal of carbon, and are employ- 
 ed as manures with great advantage. Animal or vegetable al- 
 kali increases their fertilizing power, by converting them into 
 soaps. Quicklime diminishes their, efficacy, tending to make 
 them insoluble. — Train-oil and Blubber, All the practical 
 writers on the application of train-oil and blubber, and similar 
 refuse, agree that to rectify it, it must be made into a compost 
 with a great body of earth, though they may recommend differ- 
 ent proportions under the diversified circumstances on which in- 
 dividual experience is founded. 
 
 The ingenious Dr. Hunter* advises a compost thus formed ; 
 Let \2lbs. of American potash be dissolved in four gallons of 
 water : mix the solution with twenty bushels of dry mould, and 
 fourteen gallons of train-oil. 
 
 A Correspondent of the Farmery's Magazine^ found that blub- 
 ber in a crude state, as he applied it in a first essay, destroyed, 
 instead of assisting, vegetation. Twelve years' experience has 
 led him to a most successful method of using it, which he pre- 
 sents to the notice of other agriculturists. His plan is to make 
 it into a compost in the proportion of nine loads of earth to one 
 load of blubber. He first makes a layer of earth two feet thick, 
 — building it a foot higher at the sides, three feet inward, like a 
 solid wall, to form a cavity for the blubber. When the blubber 
 has been laid on a foot in depth, similar layers ai"e repeated to a 
 convenient height till the blubber is expended, leaving three feet ' 
 of earth for the top layer : The entire heap is then beat down 
 close at the top and sides to exclude the air. In this state it 
 will ferment, and the earth becomes impregnated with the foul 
 air of the blubber. When this fermentation abates, which it 
 will do in about two mouths, the heap is to be turned over from 
 top to bottom. The bottom layer of earth, which thus becomes 
 the cover, will require some addition in thickness, to prevent 
 the escape of air by the second fermentation : When this abates, 
 the compost is again turned over ; and after a third fermenta- 
 tion, becomes fit for use. The communicator of this method 
 then adds : " The mixing or applying lime therewith, I have 
 found detrimental, as the lime reduces the blubber, and prevents 
 fermentation. I never use this compost until it is nine or twelve 
 
 * Georgical Essays. 
 
 t No. LXIIL (dated Aug. 7, 1815,) p. 287. 
 
62 REFUSE FISH. — CARRION'. 
 
 months old. In this state, 1 have applied — to both grass and. 
 tillage land — about 10 or 15 loads of the compost per acrr, tach 
 load weighing two tons ; and have cut from the grass land tliree 
 tons of hay per acre, and after-grass in proportion. I have, 
 also used it to tillage crops of Avheat, beans, and potatoes, 
 on a field of 20 acres, that has not been fallowed for ten years, 
 until this present summer, but manured annually in the above 
 proportion; and from which I have reaped five quarters of wheat 
 per acre, — five quarters of beans, — and from 1300 to 1500 pecks 
 of potatoes, — with those crops in succession. The land is a 
 strong clay ; and the only difficulty from constant cropping is in 
 keeping it clear from short twitch grass, of which if left in the 
 land, the blubber encourages the growth." 
 
 Pulverized Oil-cake has been used with advantage as a ma- 
 nure : it is an antidote to the wire-worm, especially if mixed 
 •with elder or wormwood, when it proves a certain means of de- 
 -stroying the worm ; an effect which is explained by reflecting 
 that oil is destructive to most insects. A mill has been invent- 
 ed for pulverizing oil-cake as a manure, which, with one horse, 
 will, crush five tons per day. 
 
 15. Refuse Fish forms an excellent manure, provided the 
 quantity be limited, — and, that sufficient time intervene, before 
 the plants are put in, for the combinations of animal matter to 
 be destroyed. In an instance, recorded by Mr. Young, of too 
 great a quantity of herrings having been ploughed in for wheat, 
 so rank a crop was produced, that it was entirely laid before har- 
 vest. In order to prevent a dressing of fish from raising too 
 luxuriant a crop, they should be mixed r ith earth, or sand, and 
 sea-weed. Their effects are perceptible for several years. 
 
 *•' The manure produced in the fishing villages from the mix- 
 ture of all oily and fishy substances, favours bear [barley] and 
 green crops; but when used much, renders the soil unfit for pro- 
 ducing oats : hence that soil is called poisoned.''* 
 
 16. Carrion is not commonly used as a manure, though 
 there are many cases in which such an applicatioTi might easily 
 be made. Horses, dogs, sheep, deer, and other quadrupeds, 
 that have died accidentally or by disease, are too often suffered 
 to lie exposed to the air, or immersed in water, till they are de- 
 voured by birds or beasts of prey, or entirely decomposed : 
 meanwhile, noxious gases are given off to the atmosphere, and 
 the land where they lie is not benefited. By covering a dead 
 animal with six times its bulk of soil, mixed with one part of 
 lime, and suffering it to remain for a few months, the decompo- 
 sing carcase is made to impregnate the superincumbent mould 
 •with soluble mattei's, so as to render the compound an excellent 
 manure; and by .nixing a little quicklime with it at the time of 
 
 * Sinclair's i^latintical Acccount of Scotland, vol. VII. p. 301. 
 
MALT DUST. SEA W'KED. 63 
 
 its removal, the clisagretable effluvia would be in a great mea- 
 sure destroyed. Any waste carcase may also be dissolved by 
 enclosing it in a heap of vegetable matter in a state of fermenta- 
 tion : but it is advisable to urge and sustain the fermentation at 
 a heat high enough to kill gentles and caterpillars. 
 
 17. Rape-Seed Cake, composed of the husks or bran of 
 rape-seed, is a restorative manure for arable land. It should be 
 vised when fresh, and turned in with the seed. 
 
 There is also a rape-cake formed of the ashes from burnt rape- 
 straw, which contain a deal of alkali. This is a good dressing 
 for turnips. 
 
 18. Malt Dust is a manure of great power and vivacity. 
 It answers best as a spring top-dressing. Provide for wheat ten 
 quarters per acre; barley, eight; grass-land, four. It excels in 
 stimulating a cold soil. 
 
 19. Sea weed. — In some of the maritime counties' a great 
 deal of sea weed comes in on the shore. This manure is tran - 
 sient in its effects, and docs not last for more than a single crop. 
 But for one crop it has been found to be the most productive of 
 any.* It is sometimes suffered to ferment before it is used : but 
 this seems wholly unnecessary; for there is no fibrous matter ren- 
 dered soluble in the process, while a part of the manure is lost. 
 The best farmers use it as fresh as it can be procured. Where 
 it cannot be immediately applied, a good resource to save the 
 juices draining from it is to lay it on a flattened heap of- earth 
 preparing for compost. — Sea-weed, as a manure, improves the 
 growth and taste of esculent herbs. 
 
 20. Dry Straw and Spoiled Hay, with every sort of haulm, 
 is convertible into manure for all lands. In general, such sub- 
 stances are made to ferment before they are employed; " though 
 it may be doubted (says Sir H. Davy) whether the practice 
 should be indiscriminately adopted. There can be no doubt that 
 the straw of different crops immediately ploughed into the ground 
 affords nourishment to plants : but there is an objeciion to this 
 method, from the difficulty of burying long straw, and from its 
 rendering the husbandry foul. When straw is made to ferment, 
 it becomes a more manageable manure : but there is likewise a 
 great loss of nutritive matter. More manure is perhaps sup- 
 plied for a single crop : but the land is less improved than it 
 would be, supposing the whole of the vegetable viatter could be 
 finely divided and mixed with the soil. It is usual to carry straw 
 that can be employed for no other purpose to the dunghill to fer- 
 ment and decompose : but it is worth experiment, whether it may 
 not be more economically applied when chopped small by a proper 
 machine, and kept dry till it is ploughed ih for the use of a crop. 
 In this case, though it would decompose much more slowly^ and 
 
 * Sinclair's Statistical Account of Scotland, vol. VII. p. 202.,, 
 t Elements of Agricultural Chemistry, p. 1&4. 
 
64 VEGETABLE MOULD. WOODY I'lBRE, &C. 
 
 produce less ejfftct at Jirstf yet its injincnce xvould be much more 
 /asttn^y* 
 
 On this question, and the proposed artifice for preserving the 
 whole quantity of rtluse straw or hay as manure for the soil, 
 the Reader's attention is invited to the Strictures and Sugges- 
 tions annexed to the article, Management of Manure from 
 THE Homestead. 
 
 21. Vegetable Mould, or tree-leaves decomposed, is a 
 manure so nearly fit for universal application, that no other ex- 
 ception need be made to it than the case of a soil being already 
 too rich. It is too valuable to be used on common occasions, 
 alone. It may be mixed with sand, perfectly rotted dung, ex- 
 hausted bark, or other ingredients, according to the wants of 
 the soil. 
 
 22. Woody Fibre. — "Mere woody fibre (says Professor 
 Davy) seems to be the only vegetable matter that requires fer- 
 mentation, to render it nutritive to plants. 
 
 "Tannkrs' spent Bark is a substance of this kind. Mr. 
 Young, in his Essay on Manures, which gained him the Bed- 
 fordian Medal of the Bath Agricultural Society, states that, 
 * spent bark seeyns rather to injure than to assist vegetatwn ;' 
 which he attributes to the astringent matter that it contains. 
 But, in fact, (remarks the Professor) it is freed from all soluble 
 substances by the operation of water in the tan-pit. If injurious 
 to vegetation, the effect is owing either to its agency upon wa- 
 ter ; or more probably, to its mechanical structure and effect, 
 being very absorbent and retentive to moisture, and yet not pene- 
 trable by the roots of plants."! 
 
 By * Tanners spent Bark,' in the above passage, it is to be 
 understood only the bark from which the tanning principles has 
 been extracted in a tanner's vat. This substance, when fer- 
 mented^ as directed under ••* Hot-house," in Abercrombie's 
 *' Practical Gardener," is a great auxiliary to vegetation : in 
 general, the excitement from it is only safely given through the 
 medium of mould ; but the offsets and cuttings of many plants, 
 struck into the surface of a bark-bed, will vegetate without earth. 
 See " Pinery," and Grape-house." With regard to its applica- 
 tion in the open garden, it is not a fit dressing for^ommon beds, 
 till reduced to an earthy state. 
 
 Inert Peaty Matter is similar, in respect to the absolute 
 necessity of fermenting it before it can be beneficial as a manure. 
 It remains for years exposed to vater and air without under- 
 going change ; and, in this state, yields little or no nourishment to 
 plants. Lord Meadowbank has recommended a mixture of 
 farm-yard dung for the purpose of bringing peats into fermcnta- 
 
 • Elements of Agricultuial Chemistry, p. 194. 
 flbid. 
 
SHAVINGS OF WOOD.— I'EAT ASHES. 65 
 
 tlon ; for this end, clung is well adapted, but any putrescible 
 substance will serve equally well ; and the more readily any re- 
 fuse litter heats, the bettt-r will it answer the purpose. In or- 
 dinary cases, one part of dung is sufficient to decompose three, 
 and from that to six, parts of peat : green vegetables, mixed 
 with the peat, will accelerate the fermentation. In the height of 
 summer it will take about three months — and in the season 
 comprehending winter, six months — to reduce fermented peat 
 to the state of vegetable mould, 'len cubic yards per acre may 
 be ploughed in for wheat. 
 
 Shavings of Wood, anij Saw-oust, will require as much 
 dung, or green vegetable refuse, to bring them into fermentation, 
 as the worst kinds of peat. 
 
 The FIBRE and grain of avood can be much' sooner decom- 
 posed by the action of caustic lime, than by the process of fer- 
 mentation. The young shoots of pruned trees, and similar ve- 
 getal c refuse, may be speedily converted into a manure, by be- 
 ing laid in a pit, with alternate layers of quick-lime. Mr. Brown, 
 of Derby, has been honoured with a medal, from the Society of 
 the Adelphi, for this contrivance, extending the application of 
 a principle which has been immemorially known, and recently 
 much adverted to. See above. Lime as a solvent. 
 
 23. Ashes of vegetables not woody. — The conversion 
 into ashes by combustion of vegetable refuse matter, otherwise 
 easily reducible into manure by fermentation, may sometimes 
 increase its fertilizing power in one of thfese ways : either by 
 augmenting the tendency in the manure to produce carbonic 
 acid, under the combined action of charcoal, moisture, and air, 
 — or by the effect of the alkali in relation to some other manure, 
 or the texture of the soil,— or by some ingredient which would 
 be pernicious in combination being expelled in the burning. 
 Vegetable ashes, applied as a top-dressing, may also contribute 
 to the destruction of insects and their larva;. 
 
 Burnt Straw is said, by an intelligent practical farmer,* to 
 be a manure that will insure a crop of turnips. The compara- 
 tive efficacy of burnt straw is shewn by an experiment of Mr. 
 Wright, recorded in a subsequent page. 
 
 Peat Ashes have a local utility as a top-dressing for culti- 
 vated grasses. The peat ashes of Berkshire and Wiltshire, in 
 particular, are sold at a considerable price for manuring artifi- 
 cial grass-lands, and are much celebrated for their good effect. 
 Professor Davy, having analysed as well these ashes as the soils 
 to which they are successfully applyed, found in the soils 
 themselves no sensible quantity of gypsum;) the ashes, on the 
 other hand, consisted in great part of gypsum, with a little iron, 
 a little common salt, and variable quantities of calcareous, alu- 
 
 • Jl General View of the JlgncuUurc of the East Hiding of VorkMre, bv H. K. 
 Strickland, Esq. 
 
 t Elements of Agricultural Chemistry, p. 19. 
 
 J 
 
66 NIGUT-SOIL. 
 
 minous, and siliceous earth, and sulphate of potassa. But such 
 is not generally the case with peat ashes : to produce this pre- 
 ponderating quantity ot gypsuiu, the peat must be charged with 
 vitriolic matter, and lie on a substratum of calcareous eartli. — 
 Turl-ashes are used in the Netherlands for manuring clover and 
 other grass lands; and force great crops." 
 
 X. By Excrementitioiis Substances applied as Manure. — The 
 potency of dung as a manure varies with the animal affording it. 
 
 1. Dung ov Sea-bikds.— One of the most powerful dungs 
 is that ot such sea-birds as feed on animal food. The naturally 
 sterile plains of Peru are fertilised by guano^ a species of dung 
 collected Irom small islands in the Soudi Sea, frequented by 
 sea-birds. It is used over a great extent ot South America, 
 applied in very small quantities, and chiefly for crops of maize. 
 
 The dung of sea-birds had not been used in this country as u 
 manure until a trial of it was made in Wales, at the recom- 
 mendation of Sir H. Davy ; in which instance it produced a 
 powerful but transient effect on grasses. 'I'hat sagacious and 
 candid experimentalist hence conjectures, that the rains in out- 
 climate materially injure that species of manure, unless where it 
 happens to be deposited in caverns or fissures of rock, out of 
 reach of the weather. 
 
 2. NiGHT-SoiL, in whatever state used, whether recent ot 
 fermented, is a very powerful manure, and capable of supplying 
 abundant food to plants. Saw-dust is a good vehicle for it. 
 The disagreeable smell of night-soil may be destroyed by mix- 
 ing it with quick-lime; and if exposed to the atmosphere in. 
 thin layers, strewed over with quick lime, in fine weather, it 
 speedily dries, and is easily pulverized : so prepared, it may be 
 used in the same manner as rape-seed. The Chinese mix their 
 night-soil with one third of its weight of a fat marie, make it 
 into cakes, and dry it by exposure to the sun. These cakes, 
 which are said to have>no disagreeable smell, form an article 
 ot commerce. In the neighbourhood of London, this manure 
 is prepared for sale in a concentrated state, so as to be inoffen- 
 sive in the carriage, even Avhen conveyed in bulk. The Cona* 
 pressed Night-soil may be commodiously used as a top-dressing 
 lor wheat in the spring of the year, and for all kinds of spring 
 corn, for young clovers, and other green crops ; one hogshead 
 will be sufficient for an acre, when it has been prepared with 
 due attention to the preservation of its fertilizing properties. 
 As an enriching manure, many experiments have established, 
 tliat human ordure is to be ranked many degrees before the 
 dung of the pigeon, hen, sheep, or swine ; powerful as all these 
 are. But its effects are .not so permanent as those of many other 
 substances. From recent experiments, Mr. Middleton con- 
 cludes, that no other manure can compete with it for the first 
 year after its application ; in the second year, the benefits from 
 it are very much diminished ; in the third, its effects, nearly, if 
 
DUNG OF FOWLS. 0< 
 
 not quite, disappear. Much depends on the depth of soil. 
 There can be no doubt that a substance in which the pi'inciple 
 of vegetable nutriment is highly concentered, is in pro|jortion 
 well calculated for speedily restoring or enriching land, and ior 
 forcing great crops without detriment, — supposing the staple to 
 be deep enough for tillage, and to be fidy constituted as to tex- 
 ture. On the other hand, a shallow dip of mould requires con- 
 tributions of new earth, without which forcing manures v.'ill 
 but exhaust it sooner. 
 
 On the authority of trials which seem to be convincing, 
 some writers have insisted that an inconceivable loss of valua- 
 ble fluid is incurred by exsiccating night-soil. Though thi§ 
 may be a good reason for forming this sul)stance into a compost 
 with earth, where it can be consumed on the spot ; yet it is none 
 against the use of the article in a cgncentrated state, in which 
 the loss, a*? far as the escapirig fluids are not transferred to some 
 absorbent compost, falls upon the preparer ; while the expense 
 of carriage, in regard to the solid essential part, is materially 
 lessened. 
 
 3. Pigeon's Dung is next in fertilizing power. When dry, it 
 may be employed as other manures capable of being pulverized. 
 One tenth part of pigeon's dung, four parts of sand, and five parts 
 of vegetable mould, is a good compost for a cold heavy soil. 
 
 The foUo'-.ing interesting quotation must recommend pigeon's 
 dung as a fine ingredient in a compost for melons. " The pro- 
 duce of the sub-district of Linjan (in the province of l;;ak) 
 is not inferior to that 'of the most fertile spots in Persia, 'i'his 
 iub-district is about seventy miles in length and forty in breadth : 
 it is irrigated hy canals cut out from the Zeinderood, and covered 
 with villages, which are surroimded with gardens and prodigi- 
 ous numbers of pigeon-houses. On inquiry I found that these 
 birds are kept principally for the sake of their dung, and that 
 the acknowledged superiority in the flavour of the melons at 
 Ispahan, is alone to be ascribed to this rich manure. The lar- 
 gest of the pigeon-towers will sell for three thousand pounds ; 
 and many of them \ield to the proprit-tors an annual income of 
 two or three hundred pounds each."* 
 
 4. The Dung of Domestic Fowls approaches very nearly 
 in quality to pigeon's-dung. It is very liable to ferment.f 
 
 Sir Humphrey Davy here ranks the dung of domestic fowls 
 next to pigeon's dung, without dciining what species of fowls 
 IS intended, or discriminating between the different kinds of do- 
 mestic fowls. It appears from a set of comparative experi- 
 ments recorded in the Agricultural Magazine, that Hen dung, 
 
 ' fieographicaKMcDi'jiv of the Persian Emfn're, hy Jolm Macilnnald Kennirr. 
 rolitical Assistant to Sir .lohn Malcolm, in his Mis.4ion to tl^e f;o\in of Persia, 
 4to. London, 1813. p. 110. 
 
 i F-Icmonts of A frri cultural Chemistry, p. 204 
 
68 KXI'KRIMENTS WITH MANUUES. 
 
 or the dung of the common fowl, is most efficacious ; Duck 
 clung is to.be rated second ; while Goose dung was found so in- 
 ferior that the produce from a spot manured with it was not 
 much above the average of three patches sown without manure. 
 See the statement at length, under article 6. 
 
 5. Rabbit's Dunc has been used with great success as a 
 manure ; so much so, that it has been found profitable to keep 
 rabbits chiefly for the sake of the dung, and to have the hutches 
 constructed in subservience to the object of accumulating it with- 
 out waste. 
 
 6. The DuNc; ov Cattle. — " Of the dung of cattle (says 
 Sir H. Davy,) that of hard-fed horses appeal's to be the strongest. 
 The dung of sheep and deer is thought to be more efficacious 
 than that of oxen. The dung of oxcji is supposed, by many, 
 to require a long preparation to fit it for manure. 
 
 To combat the opinion that ox-dung requires a long prepara- 
 tion. Sir Humphry then enters upon a course of argument 
 against the general practice, in regard to fermenting promiscu- 
 ous dung-heaps. " If the dung of cattle is to be used as a ma- 
 nure, like the other species of dung which have been mentioned, 
 there seems no reason why it should be made to ferment except 
 in the soil ; or if suffered to ferment, it should be only in a 
 slight degree. The grass in the neighbourhood of spots where 
 unfermented dung has been dropt, is always coarse and dark 
 green : some persons have attrilnited this to a noxious quality 
 in unfermented dung ; but it seems to be the result rather of aa 
 excess of food furnished to the plants." 
 
 The estimate founded on the experiments adverted to under 
 article 4. above, does not correspond with the order in which 
 the dung of horses and that of s^Jieep are mentioned by Sir H. 
 Davy ; and it countenances the objection held in common by 
 many practical men against the use of fresh cow-dung. Nine 
 different kinds of manure having been tried on patches of bar- 
 ley, the result was as follows : — 
 
 Hen-dwig Most efficucious. 
 
 [hick-dimg Second in power. 
 
 Sheep-dung Thii-d. 
 
 LI . 1 ^ \ ...Exactly alike. Fomth 
 
 Ihrse-dmg Fifth. 
 
 IVood-ashea Sixtii. 
 
 ^ , C Seventh. Not much above tlie averaffc of three patches 
 
 Goosc-dmi:t..< -.i . & i 
 
 ^ I sown witliout manure. 
 
 Cow-dutig Evidently prejudicial. 
 
 The quality of the land is not stated ; but possibly one cause 
 of the cow-dung being prejudicial, was the natural coldness of 
 the soil. Moreover, barley is extremely impatient of dung that 
 is not well digested and divided. But on warm arid soils, cow- 
 dung may be an improving manure, if fermented with other 
 
EXPERIMENTS WITH MANURES. 6!) 
 
 dung, or kept alone till it can be pulverized. In canvas3in[i 
 this point with an eminent liorticulturist, he informed me^ that 
 it is his own practice, and that of many gardeners skilled in pre- 
 paring choice composts, to keep cow-dung for a period of three 
 years, before they apply it either alone as a manure, or as an in- 
 gredient in a composite mould. When used in a fresh state, as a 
 manure, it shoiiTd never be alone, but mixed with any such arti- 
 cles as the following, of a warm nature, and easily pulverized : 
 the dung either of the sheep, the hog, the horse, the rabbit, the 
 pigeon, the hen, the duck, with "some of the animal manures ; or 
 with lime and sand, marie, soot, coal-ashes, the ashes of any 
 burnt vegetable, or other substance ; as the soil may want either 
 to be strengthened, or to be cooled with as much cow-dung as 
 can I)e applied without its peculiar disadvantages. Properly, 
 qualified, it is a good dressing for most shrubs and fruit-trees. 
 As the texture of the soil varies, or as a plant of a different 
 nature forms the crop, so the proportion of fertilizing power 
 which a comparative trial of manures has fixed in one instance 
 will vary in another. Still some manures seem to be universally 
 inferior ; while others, though not always standing in the first 
 place, may be relied on for conducing to a profitable return. 
 A paper by the Rev. James Willis, President of the Christ' 
 Church Agricultural Society, records two valuable experiments, 
 made to ascertain the positive effect of different manures on the 
 product of potatoes, in the same soil, with the same sort, and 
 under the same management. One experiment was on the eyes 
 alone^ or small cuttings ; and the other on the xvfiole root ; so 
 that the increase from these also may be compared. The sort 
 planted was the White Round, on a clean sandy loam, well 
 pulverized, in rows two feet asunder, twelve inches distant in 
 the row, and six inches deep. 
 
 TABLE o/EXPERIMENTS ivith the EYES only, plantedon tJic 12th Jlpril 18«). 
 
 MAMJUE. rnOTtUCT. 
 
 .1. Pig-'s (lung -..--. 1 Ijag and liulf, //er /j<^. 
 
 2. M(nvn f^ass ------ 1 bag- and 2 bushels. 
 
 3. Sheep's dung ----- 1 bag and 1 peck. 
 
 4. Coal-a.shc.s ------ 1 bag and 1 peck. 
 
 5. Hen's dung 1 bag and 1 peck. 
 
 6. ^>ld rags 1 bag 2 gallons. 
 
 7. Garden rubbish 1 bag 1 gallon. 
 
 8. Horse-dung ------ 1 bag 1 gallon, 
 
 9. Turf-asliea »----- I bag 1 gallon, 
 
 10. Turf-dust -...--. 1 bag. 
 
 11. River mud ..--.. 1 bag. 
 
 12. Cow dung 1 bag. 
 
 TABLE of EXPERIMENTS -mth the WHOLE ROOT, planted on the XOtV 
 
 Afml 1811. 
 
 MANUnU. PRODUCT. 
 
 I. Pig's dang _..,,. ^ bag ." pcckj, per Ivrf^ 
 
70 EXPERIMENTS WITH MANURES. 
 
 MAVUllE. PUOTiUCT. 
 
 2. Sheep's dting 1 ba^ and half. 
 
 3. Coal-ashes 1 bag- and half 
 
 • 4. Old rags 1 bag and half. 
 
 5. Mown grass 1 bag, 2 busii. 2 pecks, 1 gail. 
 
 6. Hen's dung 1 bag 2 bushels. 
 
 7. River mad 1 bag 1 buslicl. 
 
 8. Turf ashes 1 bag, 3 pecjp, 1 gallon. 
 
 9. Horse-dung 1 bag 3 pecks. 
 
 10. Garden rubbish ----- 1 bag 3 gallons. 
 
 11. Turf-dust 1 bag 3 gallons. 
 
 12. Cow-dung - 1 bag 3 gallons. 
 
 On reviewing the two Tables, we may perceive, that though 
 the relative powers of the manures may vary a little, Ironi ac'' 
 cidental causes, yet the increase from the Whole Root, us tried 
 against that from the Eyes with the same manure, is uniformly 
 so much greater as to prove decisively that it is more profitable 
 to set either a Half or Whole Root, than to plant Eyes. The 
 author of the Experiments also informs us, that in digging up 
 the potatoes, he found those produced from the eyes much 
 smaller. 
 
 To the passage above quoted (p. 68,) Sir H. Davy subjoins : 
 " The question of the proper mode of the application of the 
 dung of horses and cattle, however, properly belongs to the ar^ 
 tide of composite manures ; for it is usually mixed in the farm- 
 yard with straw, offal, chaff, and various kinds of litter ; and 
 itself contains a large portion of fibrous vegetable matter." See 
 next section, Management of Manure from the Home- 
 stead. 
 
 7. Hog-dung— according to the comparative statement above, 
 Cp. 68,) ranks immediately after sheep-dung, and before horse- 
 dung. 
 
 8. Urine. — All urine contains the essential elements of ve- 
 getables in a state of solution : but the various species of urine 
 from different animals difff^r in their constituents ; and the urine 
 of the same animal alters when any material change is made in 
 its food. During the putrefaction of urine, the greatest part of 
 the soluble vegetable matter contained in it is dissipated : it 
 should consequently be used as fresh as possible; but if not 
 mixed with solid compost, it should be diluted with water ; as 
 when undiluted, it contains too much animal matter to form a 
 proper fluid nutriment for absor]>tion by the roots of plants. 
 Putrid ui^ine abounds in ammoniacal salts j and though less ac- 
 tive than fresh urine, is a very powerful manure.* 
 
 MANAGEMENT OF MANURE FROM THE HOMESTEAD. 
 Composite Manure. — Under the head X. 6. it has been no- 
 ticed, that the consideration of the right mode -of applying the 
 
 * Elements of Agricultural Chemistry, p. 201. 
 
HOMESTEAD MANURE. 71 
 
 DunjT of Cattle, on a large scale, belongs to the article Compo- 
 site Manure; because it is mixed ni the farm-jar d with straw- 
 litter, and with various kinds of vegetable offal, which itself 
 contains a large proportion of hard fibrous matter. 
 
 The remarks scattered in the Elements of Agricultural Che- 
 niisiry on this subject are thrown together in the following ab- 
 stract. 
 
 Professor Davifs Theory on Composite Manure. 
 
 A slight incipient fermentation is undoubtedly ot use in the 
 dunghill ; for by means of it a disposition is brought on in the 
 woody fibre to decay and dissolve, when it is carried to the 
 land, or ploughed uiio the soil, — and -woody jihre is always in 
 .p-eat t;xccss m the refuse of the farm. Too great a degree of 
 fermentation is, however, very prejudicial to the composite ma- 
 nure in the dung-hill : it is better that there should be no fer- 
 mentation at all before the manure is used, than that it should 
 be carried too far. This must be obvious, from the following 
 considerations. The Professor's arguments may be arranged 
 under five heads : four theoretical j and one practical. 
 
 I. " An immeasurable quantity of substance disposed for con- 
 version into iood tor plants is then suffered to escape in the 
 form of drainings and vapour. During the violent fermentation 
 which is necessary for reducing farm-yard manure to the state 
 in which it is called short-muck^ not only a large quantity of 
 fluid, but like .vise of gaseous matter, is lost ; so much so, that 
 the dung is reduced one-half, and from that to two-thirds or 
 more in weight : now the principal elastic matter disengaged is 
 carbonic acid ith some ammonia; and both these, if attracted 
 by the moisture in a soil, and retained in combination with it 
 are capable of becoming nutriment to plants." — In aid of this 
 reasoning, the Professor relates an experiment, from which he 
 considers that he has obtained particular proof that the gaseous 
 matter from fermenting dung is of great utility to growing 
 plants. He introduced the beak of a retort filled with ferment- 
 ing manure, consisting principally of the litter and dung of cat- 
 tle, into the'border of a garden among the roots of some grass. 
 In less than a week, a very distinct effect was produced upon 
 the spot exposed to the influence of the matter disengaged in 
 fermentation ; the grass gr ;w with much more luxuriance than 
 in, any other part of the garden. 
 
 II. ••' There is (continues the author of the experiment) an- 
 other disadvantage in the loss of heat ; which, if excited in the 
 soil, is useful in promoting the germination of the seed, and in 
 assisting the plant in the first stage of its growth, whf-ii it is 
 most feeble and liable to disease ; and the fermentation of ma- 
 nure in the soil must be particularly favourable to the wheat 
 
72 MANAGEMENT Of 
 
 crop, in preserving a genial temperature beneath the surfacCj 
 late in the autumn, and during winter." 
 
 III. " Again, it is a general prniciple in chemistry, that in 
 all cases oi decomposition, substances combine much more 
 readily at the moment of their disengagement than after they 
 have been perfectly formed. And in fermentation beneath the 
 soil, the fluid matter is applied instantly, even whilst it is warm, 
 to the organs of the plant ; and consequently is more likely to 
 be efficient than in manure that has gone through the process of 
 fermentation, and of which all the principles have entered into 
 new combinations.'* 
 
 IV. The Professor, in another place, reminds us, that the 
 ultimate results from an excess of fermentation in a heap of 
 manure are like those of combustion. 
 
 V. " A great mass of facts may be found in favour of the 
 application of farm-yard dung in a recent state. Within the 
 last seven years, Mr. Coke has entirely given up the system 
 of applying fermented dung; and he informs me (says Sir H. 
 Davy) that his crops have been since as good as ever they were, 
 and that his manure goes nearly twice as far." 
 
 VI. Objection noticed by the Professor. — Sir Humphry then 
 candidly states an objection made by many practical Agricul- 
 turists to his system for managing composite manure. " A great 
 objection against dung but slightly fermented, is, that weeds 
 spring up more luxuriantly where it is applied." 
 
 To which he answers : " If seeds are carried out in the dung, 
 they certainly will germinate ; but it is seldom that this can be 
 the case to any extent: and if the land is not cleared of weeds, 
 any kind of manure, fermented or unfermented, will occasion 
 their rapid growth." 
 
 VII. His oxvn sPractical Application of the above Theory. — It 
 is to be observed, that the Professor admits the beneficial ten- 
 dency of a slight or incipient fermentation in mixed heaps. To 
 regulate the practice of fermenting composite manures, as the 
 basis of the heap may vary, these are his two general principles : 
 1. Whenever manures, consist principally of matter soluble in 
 WATER, their ferltientation or putrefaction should be prevented 
 as much as possible. 2. The only cases in which putrefaction 
 can be useful, are when the manure consists chiefly of animal or 
 vegetable fibre. 
 
 Agreeably to the al)ove principles. Sir H. Davy then gives 
 Directions for the Manageynent of Farm.yard Dung in the Hcap^ 
 and for its Application to the Soil: of which the following is the 
 substance. 
 
 " Where farm-yard dung cannot be immediately applied, the 
 destructive fermentation of it should be prevented as much as 
 possible. For this end, the dung should be kept dry, and unex- 
 posed to the air ; for moisture and contact with the oxygene of 
 
HOMESTEAD MANURE. 73 
 
 the atmosphere tends to excite fermentation. To protect a heap 
 irotu rain, a covering of compact marie, or of a tenacious clay, 
 should be spread over the surface and sides of it.* 
 
 " Watering dunghills is sometimes recommended for check- 
 ing fermentation : but this practice, although it may cool the dung 
 for a short time, is inconsistent with just views ; for moisture is 
 a principal agent in all processes of decomposition : dry fibrous 
 matter will never ferment. 
 
 " If a thermometer plunged into the dung does not rise to above 
 100° of Fahrenheit, there is little danger of much aeriform mat- 
 ter flying off. If the temperature is higher, the dung should be 
 immediately spread abroad. 
 
 When dung is to be preserved for any time, the site of the 
 dunghill is of great importance. In order to have it defended 
 from the sun it should be laid either under a shed, or on the 
 north side of a wall. To make a complete dung repository, the 
 floor should be paved with flat stones, a little inclination being 
 made from each side towards the centre : in the centre there 
 should be drains, connected with a small well, furnished with a 
 pump, by which any fluid matter may be collected for the use of 
 the land. It too often happens that the drainings of the dung- 
 hill are entirely wasted." 
 
 The Professor then adverts to the application of littery dung 
 on pastures. " If slightly fermented farm-yard dung is used as 
 a top dressing for pastures^ the long straws and unfermented ve- 
 getable matter remaining on the surface should, as soon as the 
 grass begins to rise vigorously, be removed and carried back to 
 the dunghill : in this case no manure will be lost, and the hus- 
 bandry will be at once clean and economical." 
 
 Free Remarks on the Theory^ and on its Practical Applica- 
 tion. — Having finished the above compendium of Sir H. l)avy*s 
 Views on the Management of Manure from the Homestead, 
 the Writer subjoins a few Strictures and Suggestions in regard 
 to the five principal grounds on which the Professor recommends 
 that composite manure should be, under common circumstances, 
 but slightly fermented before it is spent on land. 
 
 The first objection of the Author of the Elements to the re- 
 duction of farm-yard dung to the state o{ short-muck^ relates to 
 the loss of FLUID, and of gaseous matter. 
 
 Every person must admit that the subtraction of a fluid sub- 
 stance from a mass of dung must diminish the strength and rich- 
 ness of the intended manure ; and though in some cases the bulk 
 of the fluid may be rain water or waste water accidentally fall- 
 ing upon the dunghill, yet it cannot be denied that part of the 
 essence of the dung must be carried away in the drainings. Ne- 
 vertheless, where the drainings of the dunghill can be saved in 
 
 • Elements of Agricultural Chemistry, p. 20fl. 
 K 
 
74 MANAGEMENT OP 
 
 a proper receptacle, in order to be applied to heaps of dry com- 
 post, or to land under tillage, thtre is no loss to the Agricultu» 
 rist in the separation of the fluid part of the manure. 
 
 Sir Hampry Davy's plan of a well to catch the drainings of a 
 dur.ghill is sufficiently practical; and where the nature of the te- 
 nure makes it worth the cultivator's while to have such a well, 
 is perhaps as good a method as can be devised for obviating the 
 loss of fluid matter. 
 
 In other cases, where a reservoir cannot be formed for the 
 drainings from an accumulating mass of dung, it will be a ser- 
 viceable expedient to prepare a thick layer of good earth (cul- 
 tivated mould or rich loam,) raised at the edges as the basis of 
 the intended dunghill: which layer of earth, by continually recei- 
 ving the moisture draining from the superincumbent dung,will be 
 as valuable for manure, when the whole is removed as the dung 
 itself. 
 
 The escape of gaseous matter forms another part of the ob- 
 jection to fermenting Uung, above cited from Sir H. Davy. Un- 
 der a previous head, Impkovement of Soils, V. By FalloW' 
 i7ig\ the writer, in endeavouring to meet a speculative objection 
 to fallowing, founded on the escape of gaseous matter, has offer- 
 ed some considerations why that should not be estimated as a 
 loss. (p. 28 31.) 
 
 As to the escape of gaseous matter from fermenting dung, it 
 is not easy to prevent it, if the dung lie any where but in the 
 very bosom of the land. Perhaps, however, when dung must 
 be partly decomposed before it is applied, a case of mould over 
 the heap would attract, and hold in combination, much of the 
 caibonic acid and ammonia which would else escape in vapour. 
 Such mould, like that laid underneath, would be imbued with 
 sustenance for plants, but in a less degree, and only in propor- 
 tion to the completeness of the fermentation. But the coverir.g 
 of earth, would in some instances be liable to be burnt, and in 
 others be apt to prevent the free fermentation necessary to dis- 
 solve woody fibre. 
 
 As to the experiment of the vapour directed frorn the beak 
 6f a retort on some grass growing in a border, as recorded by 
 the Professor ; it may be in place to observe, that the effect on 
 grass, of which the species is not mentioned, fails to afford a 
 sufficient criterion : — had the subject of experiment been a kit- 
 chen esculent requiring a rich soil and yet impatient of rank ma- 
 nure, and had the trial been protracted till the time of flowering 
 or fruiting, some satisfactory conclusion might have been form- 
 ed with regard to the influence of the gas on the growth of the 
 plant and the flavour of its edible produce. 
 
 The second objection to the fermentation of a heap of dung 
 intended for manure, at a temperature exceeding 100 degrees of 
 Fahrenheit as a maximum, adverts to the loss of heat. The 
 
HOMESTEAD MANURE. 7$ 
 
 way in which the loss of heat is supposed by the Professot to 
 operate, involves so much that is hypothetical, that an appeal to 
 the result of trials in which the different causes that may ope- 
 rate are not distinctly measured will not be decisive in favour of 
 the theory ; because it frequently happens that an effect which 
 pretty constantly attends a particular practice is attributed to the 
 wrong cause. Now it appears contrary to nature, and to the 
 principle on which a warm climate is imitated in any forcing de- 
 partment, to excite the roots of a plant with any degree of arti- 
 ficial heat, unless there be some cover or weather-screen to de- 
 tani the warm vapour and create an atmosphere corresponding 
 to the soil ; and the seed or root ought to be protected from the 
 fermenting substance by a coat of earth. 
 
 The disadvantage from the loss of heat in manure may there- 
 fore be more correctly attributed to the. entire exhaustion of the 
 fermenting principle, and to the want of its influence in commu- 
 nicating a kindred fermentation to dry fibrous .natter already in 
 the clod, and so reducing it to a state of aliment for plants. On 
 the other hand, it may conduce to the health and vigour of the 
 plants to have the fermentation in the soil conipleted before the 
 new crop is put in, so that the growing roots may not be in con- 
 tact with putrefying substances. 
 
 The third ground of argument for postponing the decompo- 
 sition of manure till it be imbedded in the soil is drawn from a 
 principle in chemistry, that substances kscaping -from de- 
 composed BODIES ENTER INTO NEW COMBINATIONS MOST REA- 
 DILY WHEN FIRST DISENGAGED. There seems no reason for 
 contesting the practical inference deducible from this principle 
 — provided the intention be confined to promoting the combina- 
 tion of the matter disengaged from the dissolving body intimate- 
 ly with the soil : either by casing the dunghill with mould to be 
 used as compost, or by burying the manure in a clod when par- 
 tially fermented, and before it is much exhausted of the rudi- 
 ments of vegetable matter iiy drainings or vapour ; taking care 
 to have the manured soil afterwards properly turned and expo- 
 sed to the air before it is sown or planted, so that whatever gase- 
 ous matter has a natural tendency to fly off into the air may free- 
 ly escape. But the theory on which a beneficial influence is an- 
 ticipated from applying the *' fluid matter while it is warm to 
 the organs of the plant," seems to be repugnant to the process 
 of nature, and closely allied to that hypothetical branch of the se- 
 cond ground of argument already objected to. Nor is there any 
 proof that a fermenting substance is fit food for a living plant ; 
 the residuum of animal and vegetable substances purified by free 
 exposure after decomposition seems, in the circle of natural ope- 
 rations, to contribute chiefly to the bulk of ne^v plants : but w hen 
 crude animal or vegetable remains. Or the fluid or solid sub- 
 Stances rejected in the composition of animals, are administer 
 
76 MANAtiENEJSX OF 
 
 ed to growing plants, the rank manure appears, irom numerous 
 experiments, to make them flourish unnaturally at first, and then 
 to induce disease and premature decay. To give an instance 
 from each class, this is the known effect of oil, tree-leaves, urine, 
 night-soil. 
 
 The utmost extent of the fourth objection will bring the dung 
 which has cuswdWy fir e-fanged on a par with the ashes of various 
 burnt vegetables. How far the condensed power of these (a 
 specific sort being chosen for the desired effect) has been found 
 on particular soils cropped with suitable plants, to exceed that 
 of the very same sort of manure in an unfermented state, or in 
 any stage of decomposition short of combustion, is well known 
 to practical cultivators, and has been partly noticed in p, 65. 
 This objection is again adverted to under Recapitulation^ sect. 5. 
 Fire-fanging, regarded as a mischief, as an excess beyond the 
 farmer's design is easily prevented. 
 
 The fifth argument is entirely practical, and the authority ad- 
 duced in its support one of the highest. If, under different lo- 
 cal circumstances, other cultivators are led to the same conclu- 
 sion by similar experiments carried on for a sufficient course of 
 time, this single argument will have more weight than the other 
 three ; because there can be no competition between theory and 
 experience. 
 
 It is nevertheless to be observed, that the statement made 
 above, after Mr. Coke, is not clear in its import : it can have the 
 weight just conceded to it only on the construction, either that 
 some of the manure made on the farm that was expended under 
 the old system is disposable for some other purpose under the 
 new, — or that some expense in fetching manure from distant 
 places, that had used to be incurred, is saved : but if the state- 
 ment, " that the crops are as good as ever they were, and that 
 the manure goes nearly twice as far," mean only that the dung 
 when now expended is nearly twice as much in bulk or weight, 
 and covers the surface of the field more thickly in the same pro- 
 portion, the benefit is merely illusory, — the crop is confessedly 
 not increased ; while the carriage of the dung to the land must 
 be heavier, and the labour of spreading it greater. 
 
 The following Experiment of Mr. Wright, recorded in the 
 Agricultural Magazine^ N. S, No. 3, is a valuable contribution 
 on this subject. 
 
HOMESTEAD. 
 
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78 MANAGEMENT OP 
 
 To complete this experiment, there wants a notice of propor- 
 tion of weight which a heap ot rotten dung would lose in eight 
 months : three tons of strawey dung would scarcely make more 
 than a ton and a half of completely rotted dung : but when dung, 
 is reduced one-third in weight, the fermentation may be consi- 
 dered far enough advanced for agricultural pur|'Oses in general. 
 
 Supposing the original quantity to have been on a par, the 
 above experiment would be, in every instance but the first, in 
 favour of thcrotted dung: the small inferiority in the case ot 
 the turnips may be attributed to there being an excess of manure 
 above what the plant required; so that had but one ton been put 
 on for the turnips, and the other ton been reserved for the se- 
 cond crop, the benefit to both crops might have been much en- 
 hanced. It appears from the Experiments of Mr. Hassenfratz, 
 cited in Dr. Thomson's System of Chemistry^ that the times in 
 which manures begin to produce, their effects, and the length of 
 time for which they operate, are proportioned to the degree of 
 putrefaction under which they are applied. Having manured 
 two pieces of the same kind of soil, the one with a mixture of 
 dung and straw highly putrefied, the other with the same pro- 
 portions of dung and straw newly mixed, and the straw almost 
 fresh, he observed, that during the first year, the plants which 
 grew on the putrefied dung produced a much better crop than 
 the other ; but the second year (no new dung being added) the 
 ground which had been manured with the uii putrefied dung pro- 
 duced the best crop : the same thing took place the third year ; 
 after which, both seemed to be equally exhausted. Ano- 
 ther experiment of the ^ame chemist made on shavings of wood, 
 places in a striking light the slow progress of the effects of ma- 
 nure which decomposes slowly. He allowed shavings of wood 
 to remain for about ten months in a moist place, till they began 
 to putrefy, and then spread them over a piece of ground, by way 
 of manure. The first two years, this spot produced nothing 
 more than others which had not been manured at all ; the third 
 year it was better ; the fourth year it was still better ; the fifth 
 year it reached its maximum of fertility ; after which it decli- 
 ned constantly till the ninth, when it was quite exhausted. 
 
 When dung moderately fermented has been applied to land 
 sown with turnips, it has been observed that the fly is not so apt 
 to take the turnip as when the dung has been fermented in a de- 
 ficient or excessive degree. This is not to be attributed so much 
 to the vapour from the dung being offensive to the fly, for a high 
 heat is congenial to the insect, as to the plants making such quick 
 progress from a free but well-tempered excitement as to get 
 into the rough leaf and past danger before the insect lights 
 upon it. 
 
 In the sixth place, the abstract above presented from Sir H. 
 Davy's Lectures, notices a main objection to the expenditure of 
 
llOMESTEAD MANURE. 79 
 
 "lung on land when but slightly Jermented, which is, that weeds 
 spring up more luxuriantly when dung in that state is applied. 
 By way of rei)elling this objection, the Proi'essor mere iy alleges, 
 that " it can seldom be the case to any extent that seeds are 
 carried out in the dung. 
 
 Not to dismiss an important objection without obviating it, — 
 If the system of using composite dung when green, or but slight- 
 ly fermented, be adopted, the following precautions and limita- 
 tions seem necessary in collecting the materials. From the 
 dunghill intended to be so expended must be excluded many 
 things naturally mixing in the refuse heaps of a farm and gar- 
 den. These things may be comprehended under three classes : 
 — 1. Weeds; 2. Vegetable remains, containing woody fibre ; 3. 
 Particular kinds of dung which are pernicious without being 
 pulverised. But articles which contribute so materially to the 
 mass of vegetable manure need not be lost. Let one dunghill 
 be set apart as £i rot-heap for such substances as it is requisite 
 entirely to decompose before they are carried to the land, par- 
 ticularly weeds and woody fragments. 
 
 The heap to which litter and dung is carried for u^e when 
 slightly fermented should be kept at a distance from the rot-heap, 
 and nothing should be admitted into it but what is easily solu- 
 ble from the effects of heat and moisture. 
 
 An intelligent friend named in the Preface to the " Practical 
 Gardener," as a contributor of several valuable additions to that 
 posthumous work of Abercrombie — who derives his opinions 
 on practical points from a long course of experience in the di- 
 rection of large horticultural and farming establishments, en- 
 lightened by a general acquaintance with the best authors on ru- 
 ral economy — has communicated to the Writer several observa- 
 tions in respect to the application of dry litter and unfermented 
 dung on land. 
 
 In the above review of Sir H. Davy's system, under the head, 
 Imi'Rovementof Soils, IX. 17, " Dry straw and spoiled hay," 
 a method of employing these materials without fermenting is 
 suggested. If the expense of cutting dry straw by a machine to 
 prepare it for manure should not prove too great, it may be worth 
 the cultivator's while to employ it as above recommended on 
 LAND UNDER THE PLOUGH OR SPADE, provided the soU is rich 
 enoitifh in vegetable aliment to sustain the expected crop without 
 ajiu ifntnediate benefit fro fu the mamire. Manure so applied will 
 rather assist the second crop than the first. 
 
 Incontestable Exception. In land to be sown with barley, lit- 
 terv unreduced dung has a remarkably bad effect. 
 
 With regard to pastures, the agriculturist above alluded to 
 entertains, from experience, from observation, and from reason- 
 ing on theoretical grounds, a decided opinion, that neither hay 
 nor straw, nor any haulm, should be applied to the surface of 
 
80 MANAGEMENT OP 
 
 grass-land before it has undergone a sufficient fermentation to 
 ensure its easy and expeditious decoiuposition when spread 
 abroad. On grass-land, the object of combining as much as pos- 
 sible of the manure with the soil is more likely to be promoted 
 by spending it in a stage already advancing toward complete de- 
 composition, than by lodging on the gr^ound strawy litter nut at 
 all fermented ; while the face of the verdure will not be so long 
 encumbered. Nor will the gaseous matter escaping from litter 
 left slowly to rot in a pasture more benefit the land than if it had 
 exhaled from a dunghill in the homestead. It is altogether dif- 
 ferent in relation to land under the plough or spade ; by turning 
 in the manure as soon as circumstances may render fit, when 
 fermentation has just commenced and the long litter is some- 
 what reduced, the fluid matter is secured for the enrichment of 
 the land without any extraordinary pains and without injury, be- 
 cause the crop is aftcrxvards put in : the gaseous matter is also 
 secured , but whether permanently or not, may be doubted, be- 
 cause substances disposed to take a volatile form will fly off 
 whenever the bosom of the soil is opened to the air by tillage. 
 
 In order to preserve the fluids draining from dung, without 
 the expense of a reservoir, or the trouble of laying a terrace of 
 mould as the site of a dunghill, — the composite dung or litter, 
 previous to fermentation, may be laid in heaps on the field where 
 it is to be spent, and then brought to ferment by the same means 
 as dung preparing for a hot-bed, and kept fermenting for about 
 the same time before it is spread. This might be done even on 
 pasture : but it is worth consideration, 1". Whether the spread- 
 ing of a substance which has to go through the whole process of 
 fermentation over a surface of grass may not materially injure 
 the life oi* the health of the herb. 2°. Whether a smaller pro- 
 portion of manure, if laid on pasture in a state approaching that 
 of vegetable mould, may not be more beneficial, by soon mixing 
 with the soil, and doing no injury to the crop, than the larger 
 quantity of litter, which has to lie for a length of time heating and 
 partially rotting before it is dissolved and imbibed by the sward. 
 This is stated as a subject for further inquiry, in deference to 
 the Professor : but a practical farmer who has tried the matter 
 is decidedly of opinion that dung must be considerably reduced 
 to be of unqualified benefit to pasture. 
 
 To obviate one princii)al objection against employing strawy 
 unfermented dung as a top dressing for pasture^ Sir H. Davy 
 proposes to carry back to the dunghill the long straws and un- 
 fermented remnants of vegetable matter. This mode of re- 
 moving the encumbering litter would be attended with an ex- 
 pense hir be}'ond the value of the strawy refuse : and yet, were 
 such litter left in a pasture after the new herbage shoots, the 
 husbandry would be foul ; and, in the loss of manure, with ia- 
 jury to the crop, doubly unprofitable. 
 
HOMESTEAD MANURE. 81 
 
 With respect to the dung of cattle in a green or unfermented 
 state, it is said, under the head Improvement of Soils, X. 6. 
 as a quotation from Sir H. Davy : " If the pure dung of cat- 
 tle is to be used as a manure, like the other species of dung 
 which have been mentioned, there seems no reason why it should 
 be made to ferment, except in the soil." 
 
 The first ground of exception to this, is offered by Mr. 
 Wright's experiment already quoted, proving that green cow- 
 dung is pernicious on land sown with barley. 
 
 As to sheep-dang, deer-dung, hog-dung, and horse-dung, in 
 a green state, they may be applied, either singly or mixed, to 
 ploughed land in general with a good effect. The hot and fiery 
 kinds of dung should not be laid on pasture, unless tempered 
 by mixture with the colder sorts, or unless the quantity applied 
 can be minutely divided so as to facilitate both the equal dis- 
 tribution of it over the field, and its speedy sinking into the sur- 
 face. 
 
 Thus the dung of hard-fed horses should not be used green 
 on pasture land, because of its heating quality ; but it may be 
 turned into ploughed land with obvious advantage. If, how- 
 ever, an arable field is in want of instant benefit frOm manure, 
 such part of the manure as consists of horse-dung ought to be 
 fermented ; because the dung of an animal not chewing the cud 
 contains much undigested inatter, — straws of grasses, or grains 
 of corn, according to its food, broken into small parts, but not 
 dissolved : whereas the dung of most cattle that ruminate soon 
 putrefies in the soil. Cow-dung alone forms an exception ; some 
 of its peculiarities are noticed below. 
 
 Sheep's dung may be applied green, either to pasture or 
 ploughed land. The urine of sheep, richer than that of other 
 cattle, except perhaps deer, is of equal utility with their dung. 
 The dung of deer is as well adapted to improve pasture with- 
 out long encumbering the surface, as that of sheep. If sheep 
 are folded, the sooner the dung is ploughed into the land the 
 better. 
 
 Neat's dung in a recent state is cold. Another cause of its 
 bad effect alone is its tendency to cake, so that it has a tenacity 
 like that of clay : hence it is not easilv pulverized, so as to be 
 equally distributed over a field, and intimately blended with the 
 soil. When laid pure in a mass, it does not naturally heat ; but 
 it may be brought to ferment b)' a mixture of straw and hot 
 dung. If kept for a long time vmmixed with other dung, it 
 undergoes a change within itself, without losing the vegetable 
 part of its substance by fermentation. When the dung of oxen 
 is prepared as the main ingredient for exotic fruit-bearing shrul^s, 
 it should be kept for three years by itself, to lose its tenacity : 
 after which period it is full of aliment for plants, perfectly 
 
82 MANAGEMENT (>V 
 
 divested of th.it rankness which is offensive to the roots of trees, 
 and easily pulverized. 
 
 Where several dung-heaps are collected near a homestead, 
 it niay be proper to distribute the litter to each, with some 
 attention tw the kind ot crops lor which the manure is to be 
 spent. Stable dung, also the straw of corn and j)ulse crops, 
 might be set apart to augment the bulk of manure preparing 
 for arable land : offal hay, the sweepings of the hay-loft, and 
 the decayed substance of green crops, Would revert, with 
 much fitness, in the shape of compost, to fields of pasture. 
 This is only an extension of the principle on which malt-dust 
 has been employed as a manure for barley, with peculiar success. 
 Lands laid down under grass merely to prepare them for corn 
 should be treated when manured as arable, in respect to the 
 quality of tlie manure, especially when on the point of being 
 broken up. 
 
 The following practical outlines on important points in the 
 Management of Manure from the flomestead are drawn from 
 a recent work of great authority, to which e have more than 
 once appealed. As far as they correspond with communications 
 already given, it is a satisfactory corroboration : if they manifest 
 any shade of rei)ugnance to practices or opinions detailed in 
 this treatise, the circumspection of the Rt^ader will be usefully 
 awakened. 
 
 " In the Southern counties of Scotland at the present time, 
 the crops are cut very low : the straw and haulm is used for 
 absorbing the excrementitious matter of domestic animals. The 
 juices of the dunghill are carefully preserved from waste ; 
 while the heap is greatly augmented and enriched by the con- 
 sumption of green clover and turnips, and made to undergo 
 a greater or less degree of fermentation and putrefaction accord- 
 ing to the crops and soils to which it is to be applied. Dung is 
 never laid on foul land, — very rarely on pasture or hay grounds, 
 as in England ; but it is distributed economically over a third 
 or fourth part of the land in tillage, and thus over thie whole 
 farm in regular succession, at a tiine when the soil is in a state 
 to receive the greatest benefit from its operation, and in that 
 stage of a rotation when the land most demands that method 
 of recruiting it. 
 
 " For a drilled turnip crop, it is indispensable that the dung 
 be well rotted, and capable of instantly hastening the growth 
 of a plant which in its infancy is exposed to the attack of seve- 
 ral deadly eneniics. ~ But an abundant crop of potatoes may he 
 raised by the use of fresh unfermented manure ; and for clay 
 soils generally, whether tlie manure be aiiplied to a fallow unde.r 
 
HOMESTEAD MANUIIE. 83 
 
 preparatf(Mi for nn autumn sowing of wheat, or for beans, as it 
 has a much longer time to decompose in the. soil, a less degree 
 of putrefaction is required than for a turnip crop."* 
 
 Recapitulation. — For the management of manure from the 
 homesteacl, tne following rules of practice seem to result from 
 the preceding discussion of theoretical print ipks, in connection 
 with some recorded experiments. 
 
 1. To ferment dung-heaps from which mown or pulled weeds 
 and woody fibrous' refuse are excluded, until they have lost one- 
 third of their weight ; and even this in districts where manure 
 is scarce, and where the motives for spending it in the most 
 economical way are the strongest. To ferment it to this mini- 
 mum degree previously to spending it on arable land in au- 
 tumn, or at a season when some tinxe will elapse before the seed 
 is put in. To ferment and purify it in a greater degree when 
 intended for use just before a spring sowing. To ferment dung to 
 be spent on grass-land until the strawy materials begin to dis- 
 solve. 
 
 2. To ferment dung-heaps in which weeds and fibrous vege- 
 table remains or woody offal are laid to rot, until the roots and 
 seeds of the weeds and the fragments of woody matter are de- 
 composed. This kind of heap may properly be set apart for 
 pasture as far as it will extend. 
 
 3. To save the drainings from dunghills as much as possi- 
 ble. 
 
 4. To disregard the loss of gaseous and volatile matters, both 
 from the dunghill and from the surface of land ; and to estimate 
 it rather as a benefit, for the reasons givt-n under " Fallowing.""' 
 (pp. 28 — 31.) To make trial, nevertheless, low far a covering 
 of earth upon a dunghill can be converted into a manure, where 
 the matter of a dense and rapid exhalation niav seem worth in- 
 tercepting. 
 
 5. To avoid fermenting the dung-heaps described under 1. 
 until the fibrous texture is totally destroyed, and the mass of ma- 
 nure becomes cold and soft, — where the manure is to be expend- 
 *;d on a large tract, particularly on lands under the plough, — 
 chiefly for these two reasons : first, to oln-iate the loss of fluid 
 matter where a reservoir cannot he contrived ; and secondly, on 
 account of the exhaustion of the fermenting- principle, which 
 would be usefully set in action in foul soils ; rather than for the 
 ♦jther causes theoretically assigned in the Elements of AgricidtU' 
 ral Chemistry : because, admitting a principle urged by Profes- 
 sor Davy, meriting a distinct notice, that the " ultimate results 
 of excessive fermentation, are like those of combustion," it is 
 
 • r,f>rf>v:il Rf'poil o'.i tlin Agricullurftl State of PcoUand, in five vols. 4to. 
 
84 MANAGEMENT, &G. 
 
 reasonable to conclude, from the experiment related above, on 
 the ashes of 15 cvvt. of Barley Straw, that if the quantity of 
 burnt straw had equalled the weight of strawy dung, the ashes 
 would have surpassed the strawy manure in fertilizing effect. 
 The ashes of various burnt vegetables are celebrated for their 
 fertilizing power. To return to the object of checking fermenta- 
 tion beyond the proposed degree, spread the heap abroad. Heavy 
 watering Avill at once abate the heat ; but the heat will after- 
 wards revive with increased fury, unless the stack be either trod 
 down to exclude the air, or scattered and partially dried before 
 it is again allowed to ferment. 
 
 6. In gardens, and on grounds cultivated on a small scale, 
 and even on arable farms where rest by summer fallowing can 
 be superseded by a constant full supply of manure, the utility of 
 rotted dung is far above that of strawy unfermented litter or 
 slightly fermented dung ; because the latter is a nidus for in- 
 sects ; also because putrefying remains, if in contact with grow- 
 ing plants, must tend to injure the health of many species, and 
 to deteriorate the flavour of the edible parts of plants, and espe- 
 cially of esculent roots. 
 
Al>DlT10A*Ali KOTE^. 
 
 Page 26. " By Fallowing."] — While this Treatise was in the press, an ori' 
 ginal critique on the ' Elements of Agricultural Chemistry,' appeared in the 
 ' P'armer's Magazine.' The Conductor of it, who possesses great advantage 
 for comparing the projects of theory with the results of practice, has ex- 
 pressed a deliberate dissent from Sir H. Davy's doctrine ' on Fallowing.' The 
 grounds of opposition there taken coincide so closely in a few fundamental 
 points — and so substantially in their tenor and conclusion — with the observa- 
 tions made on the same subject in the preceding pages, that it may be expe- 
 dient to state that the passage in the Ti'eatise (pp. 26 — 34) was printed oft" 
 before the publication of the Magazine, and that the MS. of it had been in 
 the hands of some friendly critics sufficiently long to establish for it an inde- 
 pendent origin ; having been dissected by a surgeon, weeded and pruned by 
 a gardener, and examined for a degree by the principal of a college. This 
 still leaves to the critique in the Magazine all the force of a corroborating 
 authority; in which light I adduce an extract from it, with much satisfaction. 
 The coincidence chiefly to be remarked, is in admitting many of the Lec- 
 turer's positions advanced as chemical facts, and in deriving from them counter 
 arguments. But the points on which the Reviewer enlarges are not the same, 
 and some forcible passages in his parallel course struck me as;new, the natural 
 effect of free deduction without communication. 
 
 " But with regard to his doctrine concerning fallowing, we diffier from him 
 entirely. He thinks a clean fallow ' may be sometimes necessary in lands 
 ' overgrown with weeds, particularly if they are sands which ca.inot be pared 
 
 * and burnt with advantage ; but that it is certainly unprofitable as a general 
 
 * system of husbandry.' Now, we think naked fallow to be chiefly useful on. 
 strong tenacious clay soils ; and although it be true that the mineral earths in 
 the composition of the soil, attract no new principles of fertility from the air, 
 there are inferences deducible from his own doctrines which seem to recom- 
 mend fallows for such soils. Waving the destruction of weeds, which can be 
 more effectually accomplished by fallow, than by any drilled or green crop, 
 we observe, 1st, That by exposing soil in large clods, to the action of the 
 sun's rays, in spring and summer, it is heated to 120'' of Fahrenheit, and often 
 ■much more. By this its moisture is exhaled, and the clay comes somewhat to 
 resemble that described by our author, which had been burnt with fire. It 
 becomes more brittle, and less apt to cohere with subsequent moisture. Hence, 
 the oftener our carse soils are treated with fallow, the more friable they be- 
 come. 2d, When our author pronounced this severe censure upon fallows, 
 he seems to have forgotten what he so often states in the course of his work, 
 that after all the soluble matter in a Soil is exhausted by cropping, there still 
 remains much charcoal, the remains of woody fibre ; that this charcoal im- 
 bibes a large proportion of oxygen when the air has access to it, but that it 
 I'emains inert in the soil, unless a new fermentation be excited in it, by various 
 means which he describes. Now, in clay soils this charcoal is effectually ex- 
 cluded from imbibing oxygen from the air, but is brought into a condition to 
 do so by fallowing. The effect of this, and of its imbibing moisture, is its 
 gradual conversion into carbonic acid, and carburetted hydrogen, for the nou- 
 rishment of plants. Accordingly, esperjencetl farmer* have assured us, tfaa'. 
 
86 ADDITIONAL, NCKfES. 
 
 they have known kuid that liad been long manured, and aftenvards exhausted 
 by cropping, have its fertility more restored by a fallow than if it had re- 
 ceived a full dose of p\itrescent manure. Their experience may be accounted 
 for by data furnished by our author; and we are sorry that, in this case, 
 his conclusions seem to be in direct opposition to his premises. We so 
 far, Lowever, agree with him, that tallows are sometimes too often repeated, 
 especially on sandy soils, where drilled crops may, in general, serve their 
 purpose ; but on cohesive soils we hold them to be occasionally indispensable." 
 Farmer's Jila^asine, No. LXIV. (dated 6 Nov. 1815.) p. 48y. 
 
 P. 50. It is decomposed, &c.] — The sulphuric acid in gypsum will also com- 
 bine with ammonia. Manufacturei*s of sal ammoniac liave availed them- 
 selves cf this, afterwards disengaging the ammonia with muriatic acid. 
 This strengthens the motives for trying with gypsum composts containing 
 animal filaments. Composts, rightly proportioned, are in general moi-e effi- 
 cacious than any simple"" manures. 
 
 P. 76. The fijih argimxent is entirely practical, and the authority adduced in 
 its support one of the highest.] — The Author of the Lectures might have cited 
 anotlier great name, as an advocate for expending putrescible manure in 
 a fresh state. From the ' Hints on Agricultural Subjects,' (by .1. C. Curwen, 
 M. P. of Workington Hall, Cumberland, Esq. 2d edit. London, 1809,) it may 
 be collected, that tiie practice at the Schoose Farm was shaped upon this 
 principle, but with many capital divergencies from the broad .and indiscrimi- 
 nate track which owes its ease and simplicity to the nature of mere specula- 
 lion. 
 
 " 1 should say, . . . bury the manure as deep as possible, and then sow the 
 tui'nips directly on the manure, leaving twenty-four Inches between the rows : 
 this will afford ample room for the plough to work, v/hioh will not only 
 admit complete cleaning, but in the operation furnish that degi-ee of nourish- 
 ment to the turnip, which in very dry seasons would be highly serviceable, 
 and contribute greatly to (he weight of the crop " Hints, p. 221. 
 
 " This method would also permit of fresh stable-litter being made use of, 
 without the necessity of its undergoing that degree of fermentation which 
 reduces it at least one-third in bulk ; and, in my opinioji, still more in effi- 
 cacy. . . I have taken great care in having horse and cow dung mixed in equal 
 quantities, and the muck-heajis formed into pyramidal shapes, so as to admit 
 of their being easily covered with earth, whicli is collected for this purpose 
 from head-lands and ditclies. This method prevents the evaporation ; and 
 the gas imbibed with tlie earth makes it equally valuable with the dung. The 
 making what is called manure pies is a common practice in Ireland. It serves 
 «Teatly to increase the quantity, which must always be acceptable to the far- 
 mer." Hints, ^.222. 
 
 Mr. Curwen's method of applying manure in the field is but part of a sys- 
 tem ; therefore, before giving that method, it will be ))roper to state, thai his 
 first principle for bringing foul land into good tilth, and for superseding a na- 
 ked fallow, by the i-elief of alternate green crops, is, — to leave such a space 
 between the stitches of the green crops as will admit of working both with 
 the plough :ind hoe throughout the season -, a space double to what is com- 
 monly allowed. He holds, that by constantly turning the vacancies between 
 the rows or beds, in every direction, he can in dry weather procure for the 
 ])lants something like a compensation for rain, in the evaporation of m.oisture 
 from the earth. " The first day's exhalation from ploughincr is in the propor- 
 tion of 950lf)s of water per hour front an acre. Tne evaporation decreases on 
 the second day a third part, and continues to diminish for three or four days 
 according to the lieat of the weather, when it entirely ceases ; and is again 
 renewcil by fresh ploughing." Hints, pp 211, 212. 
 
 " A field of cabbages were this year set on a very strong stiff clay, which 
 previous to their being planted was in high tilth. The severe drought which 
 succeeded the rains that fell soon after setting, baked the ground perfectly 
 hard. The plants made little or no progress; they were seen by a friend of 
 mine, on Monday the 26th of May, as I was commencing the breaking of th(^ 
 
ADDITIONAL NOTES. 87 
 
 ground with the ploughs. I'hey were worked for the whole week. On the 
 baturday they were seen again by the same gentleman, and he could scarcely 
 be persuaded tiiey were tlie same plants The week had been very dry, with a 
 hot sun, and strong norlii-east wmds. Tlie crop of last year was allowed to have 
 been u very extraordmary one, and weighed thirty-five tons and a half jjcv 
 acre. Some of the cabbages were fifty-live pounds ; they had only fourteen 
 tons of manure upon the acre. My second principle is, to bury the dung as 
 deep as possible, in order to retard the evaporation, and keep the heat in tlie 
 ground, by preventing tlie atmosphere from acting upon it. It is a point to be 
 particularly attended to, that the manure should be kept quite dry, w hich is 
 done by having a deep trench in tUe centre of tiie sijuce between tlie rows. 
 By these two combined principles, 1 expect 1 sliall succeed in obtaining equal 
 crops, though but one lialf, and in some instances, only a third of my ground 
 is occupi'id. To pronounce decidedly tiiat this will be the case would require 
 furtiier experience than 1 can prc'cnd to boast of. So many circumstances 
 ougli! to be taken into consideration in every expei'iment, that many trials 
 must be had before it can be pronovinced altogetlier successful. 1 have the 
 tesiiniony of a very meritorious agrlouliurist, wlio iias made several experi- 
 ments upon this plan in garden husbandry, and wlio states the most favourable 
 result. 'I'lie gentleman I allude to is the Itevcrend E. lilkrton, of Colston, 
 near Ulverstone. To such as iiave no option, hke myself, but are obliged to 
 set their potatoes on wet ground, the plan 1 have followed has in one parti- 
 cular been found to answer a most admirable purj)ose. it keeps the potatoes 
 so perfectly dry, that in tliis unparalleled year of wet, where in most dry 
 grounds tlie loss by decayed potatoes has been very great, 1 have had no loss 
 whatever. 1 cannot boast of the weiglit of my crop, but indeed it was not to 
 be expected, being set a month later than the usual time, and the vegetation 
 destroyed by the frost in the very beginning of September, which is a month 
 belbre what is common. I am by no means discouraged or dubious of the prin- 
 ciple on wliich it was undertaken ; and I hope to give il -i very fair trial." 
 Mnts, pp. 213, 214. 
 
 " Dung, and .ill the animal mixtures, 1 bury as deep as possible, taking care 
 lliat they shall he deep. Lime, (the little 1 use being solely in compost,) 
 schistus, . . . sand, &c. are used for top-dressings." /{iiUs^ p. ^22. " 1 am 
 strongly inclined to believe, that where the ground is laid dry, that manure 
 can scared)' be deposited too deep , by so doing the evaporation is retarded, 
 and consequently, the manure continues for a greater length of time to fui-- 
 nish nourishment to the crop." HhUs, p. 26S. 
 
 " The experiments I have made tend to establish the double advantage of 
 well cleaning and working the ground. First, as it frees the land from weeds ; 
 and secondly, as it conduces to the growth of the crop. It aftbrds likewise a 
 very strong demonstration in favour of using the manure in its freshest state, 
 by which not only the great usual expense of making dunghills will be saved, 
 but the manure made to extend to the improvement of a third more land. 
 
 " Most of the farm 1 occupy was in that state of foulness as to require, ac- 
 cording to genei-cal practice and opinion, a succession of fallows to clean it. Be- 
 ing unwilling to adopt a system which is attended with such loss, 1 determined 
 to attempt to clean a part of it by green crops, and for such purpose to allow 
 a much greater distance between tlie stitches than Isad ever been in practice. 
 My first experiment on this plan was made on a crop of cabbages ; they were 
 planted in a quincunx form, allowing four feet and a half between each piant, 
 in order to allow room for the plough to wn-k in all directions. 1 adopted, tliis 
 plan of field husbandry, as alfording the greatest fiicility in cleaning the crop, 
 though I believe it was never before practised. Two thousand three hundred 
 and fifty plants were set per acre (eight thousand is not unusual in the com- 
 mon method,) and each plant had, by computation, an allowance of a stone of 
 manure, or less than fourteen tons per acre ; though the common quantity is 
 generally from tliirty to forty tons per acre. The manure was deposited as 
 (leep as the ]d(Migh could penetrate, drawn by four horses, and the plant set 
 directl)'^ above it. 
 
 " The plough and harrow, constructed to work betwixt the rows, were con- 
 stantly employed during the summer, and the ground was as completely freerl 
 
88 ABBITIONAL NOTES. 
 
 from weeds as it could have '"een by a naked t;illow. Tlie very surprising- 
 weight of my crop, whioli ia October was thh"ty-five tons and a half per acre, 
 and many of the cabbages fifty-five pounds each, were matter of surprii^e to all 
 who saw them, as well as to me ; and I could assign no satisfactory reason for 
 the fact. The quahty of tlie land was very indift'erent, being a poor cold clay, 
 —the manure was very deficient of the usual quantity, — the plants when set by 
 no means good, — in short, there was nothing to justify tlie expectation of even 
 a tolerable crop. 1 did not find any thing in the accounts from cultivators of 
 cabbages to afford me a solution of my difficulties, or any clue to explain it. 
 By mere accident 1 met with the Bishop of Landatl's experiment, ascertaining 
 the great evajioration from the earth, as related in his admirable Treatise on 
 Chymistry ; singular as it may appear, this very uiteresling" experiment had re- 
 mained for thirty years without any practical interences being drawn from it 
 applicable to agriculture. It apj^eared to me highly probable, that the rapid 
 advance in growth made after the hoemg of drilled grain, was attributable to 
 the absorption of the evaporation produced from the earth, and was the cause 
 of the growth of my Cabbages. With great impatience and anxiety, as I had 
 the honour to inform you last year, I looked forward to tiie ensuing season to 
 afford me an opportunity of continuing my experiment. I had long been a 
 strenuous advocate for deep burying of manure, tliough my sentiments rested 
 chiefly on opinion ; this appeared to open a field for incontestable proofs of its 
 advantage. My cabbages were last year planted on the same plan as the for- 
 mer year. Fortunately 1 extended the same principle to my potatoes, whicli 
 I was obliged to set on wet strong ground, from want of a choice of land. My 
 annual quantity of potato ground is from sixty to seventy acres. They were 
 set in beds three feet long, and two feet broad, leaving four feet and a half be- 
 tween each bed lengthways, and; hree feet endways. On eacli acre there 
 were 1230 beds, and 615(J sets, or five to each bed, viz. one at each corner, 
 and one in the middle. I'he sets of potatoes, when planted according to the 
 usual most approved practice, in three feet stitches, and nine inches apart, 
 amount to about twenty thousand. In the present, and indeed in all seasons 
 when potatoes are scarce, the savmg in planting is a considerable object A 
 great advantage also arises in being able to keep the potatoes and manure from 
 wet. In the late uncommonly wet season I sustained little or no loss in my 
 mode, which was not the case in many of the driest grounds. This plan unites 
 hand hoeing with horse culture, and will be found serviceable in wet soils. 
 
 " The lateness of planting, together with the premature frosts, prevented 
 my forming a fair judgment as to the quantity per acre which might be obtain- 
 ed by this method. My view in fixing upon this plan was, to enable me to 
 judge of the effects of evapor.ition, by being able to continue my operations 
 for a longer period. I have no doubt but that in common seasons, notwith- 
 standing the increased distance, the whole ground would be covered. 
 
 ' " My experiments on cabbages this season, commenced by planting them 
 early in April. From the rain which fell subsequently, and continued till the 
 beginning of .May, succeeded by severe east winds, the earth became so hard 
 and baked, that the plants had made very little progress. 
 
 " In the first week in June the ploughs were set to work : as they started, 
 Mr. Ponsonby, of Hail Hall, was .present, and saw the crop ; it was with diffi- 
 culty that the ground was first broken, but by the end of the week it was 
 brought into fine tilth. Notwithstanding the whole week had been dry, with 
 a strong sun antl severe east wind, yet such was the progress in growth of 
 the cabbage, that when seen again by that gentleman on the Saturday, he coidd 
 scarce be persuaded they were the same plants. 
 
 " During these operations I had been making constant experiments with 
 glasses, contrived for the purpose, to ascertain the quantity of evaporation from 
 the land, which I found to amount, on the fresh ploughed ground, to nine hun- 
 dred and fifty pounds per hour on the surface of a statute acre, whilst on the 
 ground unbroken, though the glass stood repeatedly for two hours at a time, 
 there was not the least cloud upon it which proved that no moisture then 
 arose from the earth. 
 
 " The evaporation from the ploughed land was found to decrease rapidly af- 
 I tei" the fil'bt and second day, and ceased after five or six days, depending ou 
 
ADDITIONAL NOTES. 
 
 89 
 
 \We; wind and sun. These experiments were carried on for many inontlis. Af« 
 ter July the evaporation decreased, yvliich proves tliut though the heat of the 
 atmosphere be equal, the air is not so dense. The evaporation, after the most 
 abundant rains, was not advanced beyond what tlie earth afforded on being 
 fresh turnevl up. The rapid grow th of my potatoes corresponded perfc-ctly 
 with the previous exjjerinicnts ; and their growth in dry weather visibly ex- 
 ceeded that of other crops where tiie earth was not stirred." Hints, pp. 
 269 . . 274. 
 
 " The evaporation from dang is five times as mucli as from earth, and is 
 equal on the surface of an acre to 50Uu pounds per hour. By making use of 
 dung in its freshest state, the farmer may extend his cropping to one-third 
 more land with the same quanti:y of manure. It is with regret that 1 have 
 viewed in many parts of the kingdom the quantity of manure wliich is exposed 
 on the surface, and tends to no good. I am strongly of opinion, that in all' 
 light soils, if the manure was buried in trenches as I propose, and the turnips 
 sowed above it, that more abundant crops would be procured. By cleaning 
 with the plough, great advantage would be derived to the crop, from the eva- 
 poration yielded by the eai th. Hot manure might also be used. By fermenta- 
 tion dung is reduced to one half its bulk, and its (quality reduced in a much 
 greater proportion. The manure now con)monly taken for one acre of broad- 
 cast, would if deposited whilst hot in drills, answer for four acres, and the crop 
 produced be much more." Jtints, p. 275. 
 
 These extracts embrace three important things : 1. Grekn chops with wide 
 
 INTEIIVALS. 2. TaV. APPLICATION OF TUTRESCIBLE MAXUUE IN A FUESH STATE. 3. 
 
 The pnoposEi) extension ot this puactice to light soils. 
 
 In relatiori to the first head, the copious evaporation of moisture from new- 
 ly turned earth is an important disc overy. The wide inttrvals in the green 
 crops are to provide for its free application. The iutention is judicious : but 
 in leaving intervals wide enough for a plough to work, tlie sacrifice of area 
 may outweigh the benefit, especially if the plants are not capable of reaching 
 a size in proportion to the space between them. The large field cabbages are 
 perhaps most likely to aflTord a compensation in weight, in what degree the 
 usual field crops would be thus diminished is highly requisite to be computed; 
 for if the produce from an acre is diminished every alternate year in a mate- 
 mi proportion, the sacrifice in even or eight years may be equal to one na- 
 ked fallow in the same time, or may exceed it. VViien potatoes are planted^ 
 Jn the manner above described, 
 
 3 feet by 2 
 
 Intervals of four feet and a half. 
 
 3 feet by 2 
 
 The unplanted ground is as 11 to 2; and can it be expected that the roots 
 will send out runners halfway across the wide intervals .'' or that the weight of 
 crop can sustain a competition with one raised from closer beds ? We" may 
 fionclude that further experiments produced the conviction that such green 
 fallows are on the average unprofitable ; for at the date of the letter cited in 
 the preceding treatise, (p. 31. n.) The President of the Workington Agncul- 
 tural Society had become reconciled to a summer fallow in rotation with white 
 crops, on a clay soil. But the history of experimental farming is a history of 
 revolutions in which practices which seem to be the very same are alternately 
 abandoned and resumed — seem to be, but they arc not, the very same ; lor the 
 cu'cumstances of positive knowledge are different by the a<lvancement of a 
 stage, and the preponderating obstacle which last turned the scale, is removed 
 fcy a new contrivance. Thus, a clay soil can be rendered fit for green crops 
 by a top dressing of clay ashes; (^Treatise, p. 54) and whether the system of 
 
 M 
 
90 ADDITIONAL NOTES. 
 
 summer fallowing' is cnlirtly superseded by this resource, will depend sow 
 upon a fair comparison ofllie expense and benefits found to atteml botb courses,. 
 Tlie letter of Mr. (Un-wcn to Air, Dempster, (adverted to in the preceding 
 treatise, j). 55. r.) has these two pass:i}^-es. " ( conceive that 1 am justified in 
 anticipating a rapid increase of j^reen crojjs, the means of producing them be- 
 ing now within the reach of every one." — " 1 do not think I am too sanguine 
 in viewing tlie general adoption of the system of surface soil and clay-burn- 
 ing, as dkely to be the most impoitaut discovery for the interests of agricul- 
 ture, that lias ocxurred since the introduction of the turnip into Norfolk by 
 Lord Townscnd." 
 
 The second subject wliieh wc are stimuTated to consider anew by Mr. Cur- 
 wen's f/i/iix, is, The application of putrescible manure In a fresh state. It is 
 plain tiiiit all the ins;a:ices, above collected, of this appFication relate only to 
 :irable land. 
 
 Now, if we ad* ert to the local climate, and the soil, at the Schoose Farm, 
 we may see caues wliysuch a practice, as part of a system, may confer partial 
 benefits ; and why its positive defects may be compensated, its disadvantages 
 cour.cractcd. 1. i'he climate is moist: "42 inches of rain fall in the twelve 
 months, whilst in Norfolk ihey have but 22." (Hints, p. 211.) 2. The sod is 
 "a stiff loam, partaking in a great measure of clay." (p. 262) 3. Deep 
 plougliing for tlie winter tjillow is practiced there ; the furrow at the first: 
 plougliuig for a green crop is described as from 11 to 14 inches deep, (p- 211.) 
 The .\uthor of the JJi?its notices, however, the objections which tiie advoca:es 
 of other systems have made to this part of his : " More diversity of opinion 
 is fomid to exist as to deep and shallow ploughing' than might be expected. I 
 should deem .shallow ploughing four inches; niediiun, ^ix; deep, nine: but 
 every six years I siiotdd advist- making tiie winter fallow twelve ; 1 have found 
 it in\ari:ibly to answer, and it is with satisfaction 1 see it becoming* very gene- 
 ral in tlie cou!ity of Ciunberland." (p. 237.) 
 
 To, connect these circtimstances. — If strawy litter is buried in a deep fur- 
 row under a drilled ridge, the channel thus created will at least operate as a 
 drain ; which must be a benefit on a clay soil in a moist climate. Supposing 
 the fresh litter, dung, or animal refuse lying deep from the surface, not to be 
 decomposed till tlie following season, yet if there be already in tlie soil suffi- 
 cient aliment of any kind for the plants the first year, the farmer will not be 
 di-sappointed at h.irvest time : me:inwhile there is a |)ri)vislon of manure for 
 the following year; and the same course m;iy be annually repeated with a di- 
 minished haziutl of starving tlie crop. Supposing, on the contrary, the fresh 
 manure to decompose in that silu;ition, the first season, the deep burying of 
 it leaves a l.iyer of earth for the growing roots : thus the banefid contact 
 of hot dung," putrefying vegetables, and rank animal fluids, will be eluded. 
 Stid let all the accidents be fortunate, some losses and waste must attend this 
 way of de]iositing manure, either from fibrous matter getting too deep to be 
 acted u])on by the atmosphere, or by rich fluids irrecoverably sinking into the 
 subsoil beyond the .attraction of annual crops. 
 
 As to grass-lands, the practice .it the Schoose Farm appears to be, to manure 
 these with imputrescible substances, in a shape for sinking presently into the 
 surface ; such as coal-ashes— streetrakings— sea-sand — and schistus (coal-slate) 
 previously pulverized by mixture with caustic lime, six parts to one of lime. 
 In this, there is nothing to coiuitenance the project of spreading fresh litter 
 on pasture It ma}' be observed, that although all these articles must improve a 
 soil of clay, yet only the street rakings can have niiicii jjower as containing 
 manure fbr a ])lant to consume. If clover and rye grass, under treatment which 
 decidedly improves the texture of the soil, now and then turn out a bad crop, 
 it niav be attributed to a deficiency of aliment ; plants cannot get plump on a 
 good lodging, if poorly fed. The least rapacious feeders have some ap- 
 petite. 
 
 Thiiilly, our exti'acts from the Hints contain this important suggestion : " I 
 am strongly of opinion, thiU in all light soils, if the manure was buried in 
 trenches as I jM'opose, and the turnips sowed above it, tliat more abundant 
 crops w oulil be produced." The agTiculturisl who combines knowledge with 
 invention, enlerpnze with experience, liberal communication wltlx vigilant in- 
 
ADDITIONAL NOTES. 91 
 
 *[viiiy, and candidly declares tlie results of his own experiments, will necessa- 
 rily frame a system of far.O'ng^ liolli benclicial to liis own estate, and that may 
 be transf<.-rrcfl witli benefit to lanls similar to tliose which lie has long- mana- 
 ged. If he propijse to tiunsf-r the system to an opposite sort of soil, a mere 
 opinion from sucii an autnority, strong'ly expressed, may mislead. Practical men. 
 wJK) have tried tlie application of loiij"- littery diin}^, and seen it extensively 
 tried, on light sous, pronounce decidedly that it is inferior in cificacy to weli 
 fermented manure. With rej^ard to t!ie soil itself, the want of <luc tenacity, 
 one of the inconveniences of lij^ht sandy land, i^ increased by loose litter, so 
 that the seeds are more exposed to be Ijlovvn out, or the plants unrooted. As 
 to tiie crop, it consults the hab.t of hardly ^ny jjlaiit but the potato ; and even 
 for tiiis the long litter should be cither slji;lilly fermented, or but ju)*t covered, 
 witli earth, that air, heat, and moisture, may help it to decompose. 
 
 P. 83. 7'o disregard the loss nf trasrons and vo'atile matters, both from thf dmif. 
 
 hill, and from the surface of the land ,■ and to estimate it rutlier us a henrfit.] 
 
 One of lln' principal fjaseous matters cscapinj,' from dunghills and fallows is. 
 ammonia or volatile alkali. The Author of tl^e elements dwells miicii on the 
 magnitude of this loss. But what is Ammonia ? And is it to be valued lor its 
 con'rjbutioiis to the loots o' the living plants.-' or for its cliemical agency on 
 vegetable, animal, aiul mineral substances, lodged in tiie manure or in the soil.^ 
 Ammonia is composed of nitrog'. n (or azote) and hydrogen, both gascs; the 
 first an abounding element of common air; the .second the basis of water, and 
 though not pr' perly a < onstituent of ilie atmosphere, frequently suspended in 
 it; say eigiit parts of azote to two of hydrogen ; for the proportions given by 
 chemists vi'.ry. Sir II. Davy has also separated from ammonia a .substance that 
 will unite with mercury \without destroying its n.etallic lustre. It may help us 
 to form a clearer notion of ammonia for pracuea! purposes, merely to trace 
 some of the methods of procuring ic artiiicially. The Egyptians obtained what 
 Pliny calls sal ammoniac by .sublimation from t^ie urine of camels ; and in mo- 
 dern times, the sal ammoniac of commerce, by sublimation trom fuel formed of 
 the dried dung of cattle which had been fed on a spring grass, described as 
 somewhat like clover. The European chemi.sts have successively extracted 
 t, by varied processes, from bones divested of fat— fiom urine — from promis- 
 cuous animal solids — from liai;-, fur, feathers — peltry dressed with the hair 
 
 burnt in furnaces, and sublimed ; also from soot. This pungent aroma is a1- 
 wa\'. generated by the combustion of animal iilament, especially those hollow 
 tubes and fii)res whicli ov.e their consistency to a portion of lime It occurs 
 constantly and .bundiintly in animal matt r ; wh le pure vegetable substances 
 (those which have not been mixed witii .Hnimal matter) do not invarlablv con- 
 tain it, and such as give it out on distillation afford minute or evanescent quan- 
 v.ities. The fruit of the Green (.gooseberry {KHjch (jrossuhmn) yields it on 
 analysis; also the pollen of tulips, 1 pi-rt in 2(J. From the higlily volatile na- 
 ture of ammonia, tli • plants in wliich it is found may e.isily derive it from the 
 atmos|)here ; nor can its presence in the soil be considered necessary to the 
 growth of any plant, as aliment. 
 
 Is volatile alkali to be valued for its chemical agency in a dunghill, or other 
 heap of putrescible manure ? As man\ auima' and vegetable substances, and 
 some fo.ssil.salfs, can be decomjiosid by this alkali, its presence in dmig-heaps 
 in fallows, and in all grounds preparing for crops, must be esteemed higidy 
 useful. Hut then its utility would be obslrucied, not promoted, bv arresting 
 its free action. To attempt to detain it by avoiding' fermentation is to prevent 
 its developement, if not its formation. Ammonia in action will decompose 
 the crystals of salts of iron. 'I'hus, if peat containing that pernicious com- 
 pound be laid upon a putrefying dungliill, the peat, as soon as it has been tho- 
 roughly steamed with ammal alkali as well as fermented, will be rectified no 
 less than if it had been mixed with lime. .So decayed tree-leaves, or wood 
 containing tannin, will be sooner fitte<l for manure than if fermented alone. In 
 all this we find additional motives to cover a fermenting dunghill with a case 
 of earth, or compost co .ta'ning dry vegetable matter, tliatthe fugitive vapours 
 may be intercepted before their virtue is exhausted. 
 
 To detain ammonia in the bosom of land, except in the shape of a salt, mav 
 
92 . ADDITIONAL NOTES. 
 
 require a talisman, like that which confined the genie in a coppervessel. From 
 the number ot" animal substances, inchulinp;' dungs, which evolve it, when ci- 
 tlicr burnt, or highly fermented, or mixed with caustic lime, it may be expect- 
 ed to be redundant rather than deficient in most cultivateil soils ; and the ex- 
 periments noticed in p. 5", shew that a small quantity of any salt of ammonia 
 must be diluted to great weakness, by mixture with water, not to be in excess., 
 I believe those soils in which sal ammoniac is found native, are not very fer- 
 tile ; but nothing positive can be stateil on this head, until the travellers in 
 countries which atlbrd it, give us more particular information. Muriate of am- 
 monia has been found native in some of the mountains of Bucharia, and Thi- 
 bet ; and in the waters of some lakes in Tuscany. It occurs also in small 
 quaiUities near the neighboui hood of some volcanoes. The sal ammoniac of 
 Pliny has been found in a fossil state, below the sand, in a district of Cyrenai- 
 ca, the modern Desert of Karca. 
 
 The agency of free unconfined ammonia must be of unqualified benefit to 
 fallow land, as tar as dormant vegetable matter, or other substances of which 
 the decomposition is desirable, lie in the way to intercept this stimulating va- 
 poiu' ; nor is it easy to imagine a case of exception previously to putting in 
 the ])lants. Although in a glebe which is freely turned and exposed to the 
 atmospliere, the volatile alkali, latent in animal m^unires before fermentation, 
 has a tendency to dissipate into thin air, why should we seek to obstruct its 
 spontaneous (light, at the expense of losing many cei-tain advantages, by lea- 
 ving the surface bound and indurated for want of tillage ? Could we seal up 
 the pores of the earth, two powerful considerations might reconcile us to the 
 liberation of this alkali from the bosom of a fallow, before the plants are put 
 in. On the one hand, as far as any substance is active in decomposing vegeta- 
 ble niatter, its presence in a copious degree cannot be accounted serviceable 
 to the roots of growing plants. It is true that most annual plants are Jess sus- 
 ceptible of injury from the contact of putrifying vegetable matter than slirubs 
 jmd trees; perhaps because in a small plant, of which every part is growing, 
 the principle of life is stronger ; whereas the hard roots of a tree contain wood 
 that has done growing, and is therefore unable to resist the contagion of a rot- 
 ling substance. Still even summer annuals or tender exotics are injured by 
 the steams of recent dung; and in the pivparation of stable dung for hot-beds, 
 it is found indispensable to let the first fermentation expend its strength, un-. 
 til it has come to what gardeners call a sweet heat .- meanwhile, liberated am- 
 moniac goes ofl" in clouds of vapour, betraying itself by an oflensive smell : in 
 this the object commonly proposed is merelv to expend a furious heat; but the 
 Joss of ammonia is an inseparable effect, ami no doubt of equal benefit The 
 time which elapses before common weeds will grow on a dunghill is anothei" 
 indication not to be disregarded : it seems alone a confutation of the doctrine 
 that fresh putrescible manure is at once food for plants. On the other hand^ 
 it is reasonable to conclude, that, whatever plants are constituted for receiving 
 into their growing substance, a portion of ammonia can separate from air and 
 from water sufficient supplies of its two elements, and appropriate them by 
 tlie admirable provisions of Nature's chemistry. 
 
 In regiird to the soil, it does not seem to be m.aking the most of manures con- 
 taining ammonia, to \ny them on the surface of fallow land. If they ju-e turn- 
 ed in at a slight depth, so as not to obstruct the reijuired fermentation, the am- 
 monia will steam many fragments of vegetable, anim.il, and fossil remains, be- 
 fore it e.scapes through the covering of eai'th. But ;dl such manures «re capa* 
 ble of more complete management in a compost dunghill. 
 
 THE END. 
 
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