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 THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 
 OF CALIFORNIA 
 
 PRESENTED BY 
 
 PROF. CHARLES A. KOFOID AND 
 
 MRS. PRUDENCE W. KOFOID 
 
f 
 
POPULAR TREATISE 
 
 ON 
 
 AGRICULTURAL CHEMISTRY: 
 
 INTENDED 
 
 FOR THE USE OF THE PRACTICAL FARMER. 
 
 BY 
 
 CHARLES SaUAREY, 
 CHEMIST. 
 
 I 
 I 
 
 PHILADELPHIA: 
 
 LEA & BLANCHARD. 
 1842. 
 
 ^i: 
 
!r;i<;ii?aiir) Mnn 
 
0^7 
 
 PREFACE. 
 
 The reasons which have induced me to pub- 
 lish the following treatise are, a desire to sup- 
 ply a want extensively present amongst Agri- 
 culturists, for such general knowledge con- 
 nected with chemistry as may assist them in 
 their various operations, and also the belief 
 that no work of the kind at present exists, in 
 which the subject chosen is either so fully ex- 
 plained or so well adapted for general perusal. 
 
 Until a very recent period, great doubt has 
 existed amongst all writers on Agricultural 
 Chemistry, as to the manner in which plants 
 assimilate the matter composing their struc- 
 ture, not to mention the source from which 
 these matters are derived. In the following 
 pages I have endeavoured to explain these 
 hitherto mysterious operations of nature, in 
 such a way as to be of easy comprehension to 
 all who will take the trouble to investigate the 
 subject. 
 
 I must, however, disclaim all merit to my- 
 self for any discoveries on the subject, all the 
 knowledge I possess has been derived from the 
 works of Davy, Liebig, Daubeny and John- 
 son ; and to all those who may wish to pursue 
 
 m3626^3 
 
IV PREFACE. 
 
 this science farther the above works are con- 
 fidently recommended, especially Liebig's pro- 
 found work " On Organic Chemistry, as ap- 
 plied to Agriculture," which contains all that 
 is at present known on the subject, and in which 
 the important discoveries announced are only 
 equalled by the happy manner in which they 
 are illustrated. 
 
 It must be permitted to me again to notice 
 that my object in compiling the following 
 pages, has been a desire to convey such infor- 
 mation to the Agriculturist as may be found 
 on trial to assist him in his pursuits, and to 
 explain the rationale of some of the processes 
 nature employs in the Vegetable Kingdom — 
 with what success, it is for the reader to deter- 
 mine. With this intention, and this only, have 
 I thrown together the following matter ; and 
 the little merit, if any, to which I may be en- 
 titled, must arise from the circumstance of my 
 having in some measure simplified a subject, 
 which, in its usual form, is too abstruse for the 
 general reader. 
 
 Salisbury, 
 
 November. 1841. 
 
AGRICULTURAL CHEMISTRY. 
 
 CHAPTER I. 
 
 INTRODUCTION. 
 
 mm' 
 
 The subject of the following treatise, is an 
 endeavour to explain, in a familiar manner, 
 the processes nature carries on in the assimi- 
 lation of the various substances employed in 
 the growth and nutrition of plants. 
 
 Until a very recent period the consideration 
 of this subject has been too generally deemed, 
 if not altogether beyond the range of the agri- 
 culturist, at all events, as so distantly con- 
 nected with him, as to be of little direct impor- 
 tance. And although at various periods men, 
 eminent for their talents, and for the success- 
 ful application of those talents to agriculture, 
 have called the attention of the public to this 
 subject; their endeavours have too often been 
 of little avail, and the application of science to 
 agriculture has been almost entirely neglected. 
 
 Now, however, we date from a new era. A 
 variety of circumstances have of late combined, 
 to compel a greater attention on the part of all 
 2 
 
^^mm^'^^^f^mm 
 
 b INTRODUCTION. 
 
 classes to this important study. And the re- 
 sult is, that agriculture as a science has ad- 
 vanced with rapid strides, from darkness to 
 comparative light; and from being the occupa- 
 tion of the lowest class in society, to one that 
 is regarded, and justly so, as affording a field 
 for the employment of the highest intellect; 
 and happily also one in which the greatest ex- 
 ertions may be the most beneficially employed. 
 
 The impetus that this science has received 
 may be safely committed, for its farther im- 
 provement, to the energy that now pervades 
 the agricultural classes, in the full assurance 
 that no exertions will be spared to carry it out 
 to the fullest extent. The only thing neces- 
 sary is to convey such information to the agri- 
 culturist, as shall tend to elucidate the opera- 
 tions of nature, and thus direct his energies in 
 the right path. 
 
 It has hitherto, unfortunately, been too much 
 the habit to consider a knowledge of chemistry 
 necessary, only to those connected in some 
 way or other with the practice of medicine. 
 That such an opinion is founded in error few, 
 in the present day, will be disposed to deny — 
 but when we reflect that no change of any 
 kind in any substance whatever, organized or 
 unorganized, can take place, without such 
 change being governed by chemical laws, — it 
 will be at once admitted, that the study of che- 
 mistry is absolutely essential to enable us to 
 understand either the bodies themselves, or the 
 changes they may undergo. 
 
 Chemistry, is indeed the universal science; 
 
INTRODUCTION. 7 
 
 it concerns every one, and every one ought to 
 study its principles. To every branch of the 
 manufactures of this country, this knowledge 
 has been of the most essential importance : 
 overcoming difficulties hitherto deemed insur- 
 mountable; opening new sources of employ- 
 ment, where none had previously existed; im- 
 proving others to such an extent, that the 
 different productions would scarcely be recog- 
 nised as belonging to the same class, and 
 lastly, doing all these things so much better 
 and so much cheaper than by the old processes, 
 that the national wealth has thereby been im- 
 mensely increased, and comforts and even luxu- 
 ries have been brought within the means of 
 all classes. 
 
 It can hardly be necessary to cite examples 
 in which chemistry has produced these results. 
 We have only to look at the various manufac- 
 tures of iron, glass, porcelain, the powers of 
 steam, and galvanism — destined to surpass 
 steam in its effects, the discovery of the Davy 
 lamp, &iG. to be convinced of the benefits che-. 
 mistry has conferred on mankind, and of its 
 importance as a general study. 
 
 And if this knowledge is beneficial to the 
 generality of persons, of what paramount im- 
 portance must it be to the agriculturist, whose 
 every act entails a chemical operation, and 
 who, unless he is enabled in some measure 
 to understand the cause and effect of these 
 changes, will be pursuing his avocation almost 
 by chance, or at least without the means of 
 availing himself of many advantages that may 
 
8 INTRODUCTION. 
 
 offer ; and farther, when we consider the im- 
 portant interests that are committed to the cul- 
 tivator of the soil, — that from him and his ex- 
 ertions all earthly beings derive their support, 
 either directly or indirectly ; that the produc- 
 tions of the earth constitute the vast majority 
 of the luxuries and comforts we possess ; that 
 commerce depends almost wholly on agricul- 
 ture, in its various branches, for its support; 
 that the happiness and comfort of millions is 
 dependent on the production of the earth, and 
 that human happiness is increased or dimi- 
 nished as the supply of food is abundant or 
 otherwise, we have every stimulus to apply 
 our best energies to the cultivation of the soil, 
 independently of the pleasure and satisfaction 
 with which the study of nature is always ac- 
 companied, and the individual benefits we de- 
 rive therefrom. 
 
 It may not, after what has already been 
 stated, be deemed necessary to point out in 
 what particular instances chemistry has bene- 
 fited agriculture ; but still, as some persons 
 may not see the direct and immediate connex- 
 ion that exists between these sciences, (at the 
 risk of being considered somewhat tedious,) it 
 is suggested, for their consideration, that the 
 analysis of soils is peculiarly a chemical opera- 
 tion, and that as each individual plant requires 
 for its perfection certain substances, the ana- 
 lysis of the soil in which they grow is the 
 only way to discover if such substances are 
 present, and if not, of indicating, what particu- 
 lar one is wanting, which, when discovered, 
 
INTRODUCTION. 9 
 
 may be supplied by the knowledge chemistry 
 gives us 01 other substances which may con- 
 tain it. 
 
 This is, perhaps, the most important fea- 
 ture of chemistry as applied to agriculture, but 
 still in its subordinate functions of enabling us 
 to discover the elements and consequent value 
 of refuse matters, it may be regarded as a valua- 
 ble accessory to the farmer, to say nothing 
 of its importance in pointing out remedies 
 for such minor matters as the prevention of 
 smut in corn, by the use of sulphate of copper — 
 the preservation of plants by the galvanic bat- 
 tery — the preservation of timber by the pro- 
 cess of kyanising, &c. all of which are of con- 
 siderable value in their various applications. 
 
 To these facts may be added instances, 
 where a knowledge of chemistry has created a 
 new branch of trade entirely for the agricultu- 
 rist, when if such knowledge had not existed, 
 serious consequences would have ensued. 
 The manufactures of sugar and saltpetre in 
 France during the revolutionary war are the 
 instances alluded to, and the circumstances 
 which led to tlieir introduction there are briefly 
 these:—-' That vvlien France had lost all her 
 colonies and when her coasts were held in a 
 state of strict blockade by the fleets of England, 
 the supply of sugar necessarily failed. It was 
 then that the chemists to whom the Govern- 
 ment applied in their emergency, pointed out 
 that sugar might be obtained from the grape 
 and subsequently from the beet root, and to 
 
 2* 
 
10 INTRODUCTION. 
 
 such an extent was this manufacture carried, 
 that France, until a recent period (1834,) was 
 supplied exclusively by her home manufac- 
 ture." 
 
 Again, the same causes prevented France 
 from receiving a supply of saltpetre for the 
 manufacture of gunpowder, but the same 
 energy which induced the home manufacture 
 of sugar, found a means of making saltpetre 
 from the refuse matter of farm-yards; and so 
 great was the supply from this source that it 
 enabled France to maintain her gigantic strug- 
 gle for the subjugation of Europe, for a pro- 
 tracted period, with unimpaired vigour, when, 
 had not such means been discovered, she must 
 have submitted to what she would have con- 
 sidered a disgraceful peace. 
 
 Again, chemistry enables us at once to test 
 the real value of any given substance, without 
 the uncertainty and loss of time attendant on 
 a trial ; and when it is considered how much 
 time must have been lost, how unsatisfactory 
 the results must repeatedly have been, when 
 no such knowledge existed whereby to certify 
 the progress of discovery ; the value of this 
 science may in some measure be estimated. 
 
 Other instances might be adduced, if neces- 
 sary, but enough has been said to show the 
 intimate connexion which ought to exist be- 
 tween chemistry and agriculture. Indeed, 
 the knowledge of the one is essential to suc- 
 cess in the other ; and it is hoped that the 
 spirit of inquiry which now exists universally, 
 
INTRODUCTION. . 11 
 
 will induce the establishment of Agricultural 
 Colleges, where young men, after having 
 completed their education, as far as the rou- 
 tine and practical information necessarily con- 
 nected with farming is concerned, may spend 
 a few months in the acquisition of such 
 chemical knowledge for the analysis of the 
 various soils and products, as will prove bene- 
 licial to themselves as well as the community 
 at large. 
 
 In the following pages it is intended to 
 explain, as far as our knowledge already ex- 
 tends, the manner in which plants assimilate 
 their food and the sources of its supply. To 
 do this, some preliminary knowledge is neces- 
 sary ; it is therefore proposed to consider the 
 subjects in the following order. 
 
 First — The structure and functions of the 
 different parts of plants. 
 
 Second — The general attributes of the soil. 
 
 Third — The simple bodies forming the 
 structure of the plant, the sources from which 
 they are obtained, and the manner in which 
 they are assimilated. 
 
 And lastly — The specific action of the va- 
 rious manures now in use. 
 
 In considering these subjects, it will be as- 
 sumed that the reader has no previous know- 
 ledge of the question. No apology is therefore 
 offered for the elementary character which each 
 chapter will exhibit. It has been the desire of 
 the writer to explain every circumstance as 
 fully as possible, and although the use of tech- 
 nical terms is necessarily unavoidable in such a 
 
12 ' INTRODUCTION. 
 
 work, still a moderate degree of attention will 
 overcome all the difficulties, and it is hoped 
 that the information afforded, is of that kind, 
 that no one will regret the trifling efforts it 
 may have cost him to overcome them. 
 

 CHAPTER II, 
 
 DN THE STRUCTURE AND FUNCTIONS OF THE 
 DIFFERENT PARTS OF PLANTS. 
 
 The first step, necessary to the proper com- 
 prehension of the processes nature employs in 
 the assimilation and growth of plants is a per- 
 fect knowledge of the organs each plant pos- 
 sesses, and the functions these organs perform 
 in the development of the different parts of the 
 vegetable structure. 
 
 Without such knowledge it will be impossi- 
 ble to understand how plants derive their nutri- 
 ment from the air and the soil, and indeed it is 
 and must be the basis of all information on the 
 subject. 
 
 It is proposed, therefore, to give such a gene- 
 ral description of the functions of each organ 
 of plants, as connected with the assimilation of 
 their various component parts, before proceed- 
 ing to the consideration of the matter so assimi- 
 lated. 
 
 It is first necessary to note, that certain con- 
 ditions are as necessary in the vegetable as in 
 the animal kingdom for the development of a 
 perfect plant. 
 
 In the latter case a due supply of fresh air. 
 
14 STRUCTURE AND FUNCTIONS 
 
 food and liquid of some kind are the essentials 
 necessary for the sustenance of animal life, and 
 should but one of these be wanting, although 
 the other two may be supplied in excess, death 
 will ensue. So it is with plants; certain con- 
 ditions are necessary to bring them to maturity, 
 and those of each genus require a peculiar 
 treatment to bring them to perfection; and it is 
 the study of these peculiar conditions and the 
 successful application of various manures to 
 forward the development of the different organs, 
 or the application of other substances to neu- 
 tralize any quality in a peculiar soil, which 
 would be prejudicial to the growth of a certain 
 crop, which constitutes agricultural chemistry 
 in its widest and most extended sense. 
 
 As a general rule, all plants consist of a root, 
 stem, and leaves, and these organs again have 
 a direct and distinct reference to the production 
 of a fruit, the which being accomplished, the 
 plant either dies entirely or lies torpid for a 
 season, until a succession of the same circum- 
 stances which gave it life in the first instance, 
 shall again call its productive organs into 
 action. 
 
 The root of a plant performs the two impor- 
 tant offices of retaining it in a fixed position and 
 of supplying it with a great part of its nourish- 
 ment, and it may therefore be considered as 
 analogous in some measure to the mouth and 
 limbs of an animal. 
 
 It is not at all necessary in this place to con- 
 sider the different forms the root assumes in 
 different plants, it is sufficient for our purpose 
 
OF PLANTS. 15 
 
 to know that the roots of all plants perform the 
 same function, that of absorbing nutriment from 
 the surrounding substances for the nutrition of 
 the plant. 
 
 It may be and is matter of wonderment, that 
 such a vast variety of shapes, should be given 
 to an organ, provided in all cases for the same 
 purposes; but here our inquiry must cease, an 
 all- wise Providence has so endowed and created 
 them, and man even with his finite under- 
 standing is capable of appreciating the benefit 
 he derives from such an arrangement. 
 
 A root usually consists of several parts, the 
 body, the crown or collar, the branches and the 
 fibres, which latter seem indispensable in all 
 plants. 
 
 The most essential part of every root is the 
 crown, which is the portion of the plant be- 
 tween the stem or leaves, and the body of the 
 root. In many plants of a hardy nature nearly 
 the whole of the body of the root ma}^ be cut 
 away, and yet, if the crown be uninjured, still 
 the plant will flourish, but in the generality of 
 plants, if the crown be injured, no matter how 
 perfect soever the body may be, the plant is 
 usually destroyed. 
 
 This remark applies to almost all kinds of 
 grasses, but there are some so tenacious of life 
 (such as the common couch-grass and plantain) 
 that they can only be extirpated by removing 
 every portion of the body of the root. 
 
 When the crown of a root is slender it dries 
 up as the seeds ripen, and the plant soon dies; 
 such plants are termed annuals, as wheat, bar- 
 
VB( STRUCTURE AND FUNCTIONS 
 
 ley, oats, &c., but when the crown, from any 
 cause, such as the soil, climate, or culture, is 
 rendered strong, such annuals are brought to 
 grow two years and then are called biennials, 
 or for a succession of years and then are called 
 perennials. 
 
 The fibres, though an essential part of each 
 root, may be removed in most cases without in- 
 jury to the plant, provided the crown is suf- 
 ficiently healthy and vigorous to push out new 
 ones. It is at the tips of these fibres that the 
 spongelets are placed, which absorb the pabu- 
 lum from the soil, and in the event of the 
 spongelet being removed by any cause from the 
 point of the fibre, two lateral shoots imme- 
 diately are thrown out, (provided the plant is 
 sufficiently vigorous to bear the temporary loss 
 it thus sustains,) each provided with its sponge- 
 let, and thus the destruction of the one becomes 
 a source of strength to the plant. It was on 
 this principle that TuU's famous horse-hoeing 
 husbandry was founded: "that by ploughing 
 between the rows of wheat, and thereby cutting 
 off the tips of the fibres, that for every sponge- 
 let thus destroyed two were reproduced by the 
 plant, thus giving the plant two spongelets 
 where one had previously existed." There 
 were other collateral benefits to be derived from 
 this method, but the one in question was one of 
 the principal. 
 
 That plants have the power of accommo- 
 dating themselves to circumstances is proved 
 in a most beautiful manner from the fact, that 
 when planted in a dry and arid soil an infi- 
 
OF PLANTS. 17 
 
 nitely greater number of fibres and spongelets 
 are produced, than when the same plant is 
 grown in a moist and fertile soil. 
 
 The fibres, like the leaves of trees, are pro- 
 duced annually, in some cases falling off like 
 leaves, as in the Dahlia; in others increasing 
 in size, and becoming harder like the parent 
 body of the root, and subsequently throwing 
 out new fibres themselves, as is the case with 
 almost all large trees. 
 
 Besides this property of absorbing nutriment 
 from the soil, these fibres have the power of 
 throwing off that matter absorbed by the 
 spongelets which is either unnecessary or nox- 
 ious to the plant, and this may be one of the 
 causes Vvhich prevents plants of any kind from 
 being successfully cultivated on the same soil 
 during a succession of years. 
 
 It may here appropriately be mentioned that 
 darkness, or at all events the absence of light, 
 is essential to the development of the fibres of 
 the roots. 
 
 The stem is the next part to be considered, 
 but the functions it perforins in the vegetable 
 creation are so subordinate to those performed 
 by the root and leaves, that it will occupy but 
 little time to become acquainted with its of- 
 fices. 
 
 The stem of all plants rises immediately 
 from the crown of the root, and is consequently 
 always above the ground. The same variety 
 prevails in this part of the plant as in the root, 
 for instance : the stems of wheat, barley, and 
 the grasses rise to some height and are termed 
 3 
 
18 STRUCTURE AND FUNCTIONS 
 
 the straw ; the stems of mushrooms, fungi, &c. 
 are termed the stalk, and the stem of the straw- 
 berry is termed a runner, all of them being ap- 
 propriately described from the appearance each 
 presents. 
 
 The functions performed by the stem are lit- 
 tle more than that of conveying to the different 
 parts of the plant the liquids absorbed by the 
 spongelets of the root. It is somewhat porous, 
 and evaporation of the useless moisture of the 
 plant takes place to some extent on its surface, 
 but compared in this respect with the leaves, 
 its office is unimportant. It consists in all 
 cases of cellular tissue, containing albumen, 
 with a large portion of the earthy and alkaline 
 matter absorbed by the roots, and it partakes 
 largely also of the character of the plant itself 
 in its ultimate analysis, but frequently contains 
 a deposite of resinous or oleaginous matter, dif- 
 fering widely from the products of the other 
 parts of the plant. It possesses the property 
 of throwing out fibres and spongelets under fa- 
 vourable circumstances, and this mode is one 
 of the most common means employed for the 
 propagation of particular shrubs. 
 
 The leaves of plants are the next subject for 
 consideration, and the important offices they 
 perform in the nutrition of all plants will merit 
 a careful investigation. 
 
 Nature, in all her operations, as far as hu- 
 man knowledge extends, is perfect. Sufficient 
 means are always employed to obtain a given 
 result; and hence we may justly infer that 
 leaves from their immense number and from 
 
OF PLANTS. 19 
 
 the great extent of surface that they offer to 
 the action of the air, perforin a most important 
 part in the vegetable kingdom; and it will 
 be seen from the functions now about to be de- 
 scribed, that their importance is not overrated. 
 
 Leaves perform, in the vegetable kingdom, 
 the same offices as the lungs in the animal 
 kingdom. Through them, from the pores co- 
 vering their surface, the respiration of the plant 
 is carried on, and more than this, for at the 
 same time that the respiration is going on 
 through their pores, a constant assimilation of 
 one of the gases of the atmosphere (hereafter 
 to be described) is also taking place — and from 
 this source the plant derives a considerable 
 portion of its nourishment; to this also we 
 must add that a constant chemical action is 
 always in operation in the leaves, in the forma- 
 tion of the resinous, and oleaginous, and acid 
 matters they contain. These processes of the 
 leaves are constantly in operation, from the 
 first formation of the leaf until the seed is per- 
 fected, and they only cease when, from the 
 ripening of the fruit, their assistance is no 
 longer required. 
 
 It is important to remark that light is indis- 
 pensably necessary to this function of plants ; 
 in its presence, both the mechanical action of 
 evaporation of the watery parts and the secre- 
 tion of the various gases is carried on vigor- 
 ously ; but in its absence the plant loses this 
 power, and becomes subject in its turn to the 
 action of the oxygen of the atmosphere. 
 
 In speaking of the root of plants it has been 
 
20 STRUCTURE AND FUNCTIONS 
 
 noticed, that one condition essential to that part 
 of their structure is darkness; and now it is 
 found that light is equally necessary for the 
 stem and leaves and other green parts of the 
 plant. If proof were wanting to convince us 
 of the almighty mind of the Being who has so 
 wisely constituted this world, it might be found 
 in the simple yet perfect arrangement now 
 under consideration. It is a proof of the most 
 perfect adaptation of the plant, to the condi- 
 tions and circumstances necessary for its 
 growth. 
 
 We now come to speak of the seed or fruit 
 of plants. The object to which all the other 
 functions of the plant are subordinate, or to 
 which at least all parts have reference, and one 
 which in its importance to mankind cannot be 
 too highly appreciated. 
 
 Seeds vary in size, colour, shape, &c. to such 
 an infinite extent as to be scarcely within the 
 scope of human understanding; but all of them 
 possess one uniform arrangement for the protec- 
 tion of the germ from injury, and it will be im- 
 portant to consider what this general arrange- 
 ment is, and also the changes that the seed 
 undergoes in the process of germinating. 
 ' All seeds consist of a farinaceous pulpy mat- 
 ter, covered on all sides by two or three mem- 
 branes which serve to protect the seed from 
 any casual injury. The pulpy matter contains 
 at one end, the heart, or as it is more correctly 
 termed the germ or embryo plant, and in all 
 cases it must be remarked that the pulpy fari- 
 naceous matter is the proper food of the nas- 
 
OF PLANTS. Vl 
 
 cci.t germ. Some seeds are farther protected 
 by a hard outer covering; but this remark ap- 
 plies only to the seeds of trees. Although 
 the gradations from the hard external shell of 
 the apricot stone, to the membranous cover- 
 ing of the wheat are so gradual, that the line 
 where the one begins and the other encjs, is 
 difficult to be decided on, and indeed whether 
 inclosed in the shell or membrane, the changes 
 ail seeds undergo in the process of germinating, 
 seems to be precisely the same, and it may be 
 worthy of notice here, that so effectual is the 
 membranous covering in protecting the germ 
 from injury, that seeds found in the mummies 
 taken from the pyramids of Egypt, which 
 must be at least 3000 years old, have vegetated, 
 when planted in favourable circumstances; and 
 farther, seeds brought up from the interior of 
 the earth in sinking wells, mines, and other 
 excavations have also germinated, although the 
 period when such seeds could have been depo- 
 sited in such positions is altogether beyond hu- 
 man conception. 
 
 The circumstances necessary for the germi- 
 nation of the seed depend externally on heat, 
 moisture, air, soil and situation ; although these 
 two latter conditions are not in all cases indis- 
 pensable. 
 
 Moisture is absolutely necessary for the seed 
 when planted, its first action is to swell by ab- 
 sorbing the pulpy matter of the pod, which 
 then bursts open and allows the air to act in 
 concert with the water thus absorbed, in cre- 
 ating new compounds, such as starch, sugar, 
 
 3* 
 
22 STRUCTURE AND FUNCTIONS 
 
 resin, &c. which form the pabulum or nou- 
 rishment necessary for the young plant in its 
 first stage of existence, and before its organs 
 are sufficiently developed to obtain a supply of 
 food elsewhere. 
 
 Heat follows next, and is equally indispen- 
 sable to the germination of the seed. A tem- 
 perature below 32° or much above 120° are 
 the extremes, beyond which vegetation does 
 not take place ; in the one case from the freezing 
 or extreme cold, closing the pores of the seed 
 to the moisture, and in the latter from the ex- 
 treme heat, causing the fluids of the seeds to 
 be too much expanded, when decomposition of 
 the parts takes, place. 
 
 Air is also an essential ingredient in the ger- 
 mination of seeds, from the presence of its oxy- 
 gen. And it is probable, to the absence of 
 this cause, that seeds found buried in the earth, 
 under what would otherwise be considered fa- 
 vourable circumstances for their growth, have 
 lain so long dormant. 
 
 Light, so necessary to the favourable growth 
 of the plant itself, is prejudicial to the deve- 
 lopment of the germ, from its power of disen- 
 gaging the oxygen necessary to the vitality of 
 the embryo of the plant. 
 
 Soil and situation need not here be discussed, 
 as these attributes will be considered more at 
 large in the ensuing chapters. 
 
 Electricity is also presumed to have an im- 
 portant effect in causing the germ to vegetate 
 and assume the functions of an organized plant, 
 but as yet this is only a surmise. The know- 
 
OF PLANTS. 23 
 
 ledge of this omnipresent agent is yet too 
 limited to say if such is the case, and if so, to 
 say how it operates, but that it does extend and 
 exert its influence on such objects is almost 
 beyond a doubt. 
 
CHAPTER III. 
 
 ON SOILS. 
 
 To enter fully into this branch of the sub- 
 ject, and with all the detail which its impor- 
 tance deserves, would require a volume of it- 
 self, and would far exceed either the limits or 
 the intention of this elementary work. 
 
 It must suffice here that a general outline of 
 the characteristics of the soil is given ; that the 
 source from which its fertilizing properties are 
 derived, is pointed out; and that attention is 
 called to the benefit to be always derived from 
 a judicious admixture of the various kinds of 
 soils. This, with a few remarks on the neces- 
 sity that exists for a rotation of crops, and the 
 benefit that arises from allowing the land either 
 to lie fallow or at least to be cropped only with 
 such crops as do not exhaust the soil, and 
 which from this circumstance are termed fal- 
 low crops, will comprise all the information it 
 is proposed to bestow on this subject. 
 
 Soils are distinguished by a variety of names, 
 according as a particular substance predomi- 
 Uratesin them. Thus calcareous soils are those 
 containing lime in greater quantity than any 
 other ingredient. 
 
ON SOILS. "25 
 
 Argillaceous soils are recognised from the 
 clay and the oxides of iron, which predominate 
 in them. 
 
 Peaty soils are those where decayed vegeta- 
 ble matter exists to the exclusion of almost all 
 other matter, and all other soils are equally re- 
 cognised and distinguished from the character 
 of the predominant ingredient. 
 
 Sir Humphrey Davy, in his profound work 
 on Agricultural Chemistry, when speaking of 
 soils, says **That for all useful purposes, the 
 various soils are sufficiently recognised, and 
 that any attempt to class them with scientific 
 accuracy, would be a vain labour, the only thing 
 necessary being a clear comprehension of the 
 terms made use of 
 
 But in quoting this passage it must be dis- 
 tinctly stated, that this opinion does not mili- 
 tate against that previously expressed, in which 
 a correct analysis of the component parts of 
 the soil is considered to be of the first impor- 
 tance, and one on which the value of agricul- 
 tural chemistry mainly depends. It is merely 
 intended to state that to attempt a description 
 with scientific accuracy of the various soils 
 would be a hopeless task, without at all detract- 
 ing from the value of a correct analysis in every 
 position where it is possible. 
 
 It is therefore assumed that the recognised 
 distinctions already existing are sufficient for 
 the purposes of agriculture, and the considera- 
 tion of the functions performed by the soil and 
 the fertilizing properties it contains is at once 
 proceeded with. 
 
26 ON SOILS. 
 
 Soil is the general name applied to the sur- 
 face of all sorts of land. It consists of the fine 
 powdery material formed by the chemical and 
 mechanical action of the air, water, and differ- 
 ent degrees of temperature, from the primitive 
 rocks of the earth, incorporated with each other 
 in an endless variety of proportions, and mixed 
 with decayed and other vegetable matter in 
 every stage of decomposition. 
 
 The soil thus formed affords a place for ve- 
 getable life, by enabling the seed and plant 
 there to fix itself mechanically to one spot, and 
 by its peculiar properties of affording moisture 
 and the other ingredients necessary for the de- 
 velopment of plants in all their stages, to arrive 
 at maturity and thus furnish a supply of food 
 to man and animals. 
 
 The various ingredients necessary for vege- 
 table life all exist in the primitive rocks of the 
 earth, and by their destruction these ingredi- 
 ents are rendered available for plants, and as 
 farther this disintegration is constantly, going 
 on, it must as a matter of necessity arrive that 
 a greater power daily exists for the support of 
 the vegetable creation. 
 
 The substances produced by the decompo- 
 sition of the various strata of the original rock 
 are potash, soda, phosphoric acid, magnesia, 
 lime, and silex. Hereafter, in the consideration 
 of these various substances, their specific mode 
 of action on plants, and the immediate sources 
 of their supply, will be described — here they 
 are only noticed as being set free by the disin- 
 tegration of the original rock of the earth. 
 
ON SOILS. 27 
 
 That such disintegration is constantly going 
 on, is evident from many causes — and one 
 which is, perhaps, the most convincing of any 
 is, that the lavas in Sicily, which have been 
 thrown out from Mount Etna within a compa- 
 ratively recent period, are now found covered 
 with a fertile soil, which could only have arisen 
 from this source — and which is proved to be 
 derived from this cause by the chemical analy- 
 sis of the rock itself, which yields the sub- 
 stances found under other modifications in the 
 soil itself 
 
 This fertility is owing to the alkalis which 
 are contained in the lava, and which, by expo- 
 sure to the combined action of the air and mois- 
 ture, are reduced to a state capable of being 
 absorbed by plants. 
 
 A soil vvliich has been subjected to this influ- 
 ence for ages, and from which no crops have 
 been removed, will be enabled to support a 
 luxuriant vegetation for many seasons succes- 
 sively, without any supply of manure, simply 
 because the soil is full of the alkaline matter, 
 phosphates, and other ingredients necessary for 
 the growth of plants; but when under cultiva- 
 tion and when the crops are removed from it, 
 it must become gradually exhausted, and un- 
 less the alkaline property removed with the 
 crop is restored in the shape of manure to the 
 land, the soil will be eventually quite' unable to 
 support a crop and bring it to perfection. But 
 if when such exhaustion of the land has oc- 
 curred the soil is allowed to lie fallow or 
 cropped only with such plants as do not require 
 
28 ON SOILS. 
 
 such alkaline matter for their nourishment, the 
 soil will, by the continuous action of the air, 
 &c., in effecting the decomposition of the pri- 
 mitive rocks, again acquire a supply of those 
 alkaline salts to be enabled to perfect a crop. 
 
 The plants which may be termed strictly 
 fallow crops are beans, peas, and buckwheat, 
 as the ashes of these vegetables when analyzed 
 scarcely yield a trace of the alkaline salts, or 
 phosphates; next to these may be classed tur- 
 nips, cabbage, beet and potatoes, which exhaust 
 the soil more than the preceding, but still not 
 to the extent that the white crops, such as oats, 
 barley and wheat, which require such a sup- 
 ply of the alkalis and phosphates for perfecting 
 a crop as usually to exhaust the soil in one 
 season. 
 
 A peculiar case of the rotation of crops oc- 
 curs at Manningford, and other places in the 
 neighbourhood of Pewsey in Wiltshire. There 
 the invariable rotation is wheat and beans, and 
 has been so for fifty years past, experience 
 having taught the agriculturist there, that that 
 systeui is the best, and a knowledge of chemis- 
 try explains how it is, that it is so. 
 
 Wheat absorbs the native phosphate and al- 
 kaline salts, leaving the soil, we will suppose, 
 for the sake of argument, quite exhausted of 
 these necessary ingredients, and leaving of 
 course the excrement which all plants exude 
 from the roots during their growth. The suc- 
 ceeding crop beans, does not require for its per- 
 fection either phosphates or alkaline salts, sim- 
 ply a supply of carbon, and therefore as far as 
 
ON SOILS. 29 
 
 the wheat is concerned, the earth is, by the dis- 
 integration of the original matter of the soil, 
 again acquiring a supply of those salts and 
 phosphates, during the growth of the beans; 
 and this, with the manure which is applied, is 
 sufficient to furnish a supply for the w^heat in 
 the succeeding season. In addition to this the 
 excrement of the one may furnish the pabulum 
 for the other, and thus each has a beneficial ef- 
 fect on the succeeding crop. 
 
 Experience also has taught us, that beans 
 alone are not a sufficient food for horses. It is 
 customary always either to w ix chaff, or gene- 
 rally bran with the beans, to supply the neces- 
 sary amount of phosphates required by the 
 horse for supplying the waste of the body ; and 
 thus chemistry explains and confirms the po- 
 licy of this mode of treatment which long ex- 
 perience only has taught. 
 
 Decaying animal and vegetable matters is 
 also another and a very fertile source of the 
 supply of nutriment to plants — and all soils 
 contain more or less of this matter in some 
 state or other — but the consideration of the 
 immediate effects produced on vegetation by 
 these substances, is likewise postponed until 
 its effects are explained in a succeeding chap- 
 ter; their presence is only noted here as form- 
 ino^ one of the principal constituents of the 
 soil. 
 
 From the remarks we have already made, it 
 
 will be evident that no plants which require 
 
 the same substances for their support can be 
 
 successfully cultivated, either together or in 
 
 4 
 
mmmm^mmmmmi'f'^mmm^^Wfm^ ^mm 
 
 30 ON SOILS. 
 
 succession, because the soil requires time to 
 recover itself, or to reproduce a supply of the 
 various substances necessary for their perfec- 
 tion : but in addition to this cause there is ano- 
 ther, which, under the rotation of crops, is 
 indispensable in a judicious system of agricul- 
 ture. 
 
 From experiments that have been made by 
 DecandoUe and others, and repeated by Leibig, 
 it is established beyond all question that the 
 roots of. plants throw off an excrement during 
 the progress of their growth, and that the ex- 
 crement of each plant is peculiar to itself. And 
 farther, that the presence of such matter in a 
 soil, impedes the growth of plants of the same 
 kind, whilst in some instances it becomes a 
 source of nourishment to others. 
 
 This fact is another argument in favour of 
 the necessity of a rotation of crops. And 
 much will depend upon the nature and cha- 
 racter of the soil itself as to what time should 
 elapse before a certain crop may be success- 
 fully repeated. 
 
 If Ihe land is light and porous this excre- 
 mentitious matter will in all probability be so 
 decomposed by the combined action of the air 
 and moisture, as to be entirely dissipated in 
 the course of one or two seasons; but if, on the 
 contrary, the soil is of a stiff retentive charac- 
 ter, four, five, and even six years may elapse 
 before this matter shall be so destroyed as to 
 allow a repetition of the first crop. 
 
 It may be argued against this theory, that 
 many crops, such as Lucerne, for instance. 
 
ON SOILS. 31 
 
 grow for many years successively in the same 
 spot ; but a careful attention even to this crop 
 will convince ev.en the most skeptical of the 
 universality of this law. If, for instance, a 
 field of Lucerne is planted, and no manure of 
 any kind is applied, it will be found after a few 
 years to have lost much of its fertility, and that 
 the produce is lessened considerably in amount; 
 but that, after being in this state for some time, 
 perhaps a year or two, the plant seems to re- 
 cover itself, and even an increased vegetation 
 takes place. 
 
 This is to be accounted for thus — the plant 
 during the first year of its growth throws off a 
 quantity of excrement, which increasing year 
 by year in the soil faster than it is decomposed 
 by the air, at last is so prevalent, that the plant 
 can obtain scarcely any nutriment from the 
 soil, and consequently is enfeebled in its growth, 
 and throws off comparatively no excrementi- 
 tious matter to the soil. When this state of 
 affairs has arrived, the action of the air on this 
 matter gains on it, and in the course of one or 
 two seasons the whole of it is so reduced as to 
 act as a stimulus to the plant itself, and give 
 it apparently a new life, by supplying it with/ 
 a quantity of carbon for its assimilation. 
 
 This decomposition may however be other- 
 wise affected by constantly turning the land, 
 and by adding small proportions of quick lime, 
 which would hasten the process of decay, and 
 thus prevent the barrenness of the plant from 
 taking place. 
 
 Thus the rotation of the crops is necessary 
 
S2 ON SOILS. 
 
 from two causes : the first, that each plant or 
 crop takes away from the soil the matter suited 
 to itself and thereby exhausts it; the other, 
 that it leaves an excrement behind which acts 
 as a poison to plants of the same kind ; but 
 which excrement in some instances serves as 
 the nutriment of other plants, and in all cases 
 may be destroyed by exposing it to the action 
 of the air, or by mixing with it such manures 
 as will readily effect its decomposition. 
 
 After what has been already said on the ex- 
 haustion of soils by a particular crop, it will be 
 hardly necessary for us to point out the advan- 
 tages that may be derived from a judicious ad- 
 mixture of various soils, in which the defi- 
 ciencies of the one may be supplied by the 
 excess of the others. Indeed it is on this 
 principle, that of supplying a soil with the 
 ingredients necessary for the support of plants, 
 and neutralizing other substances, which may 
 be prejudicial to them, that the whole merit 
 of agricultural chemistry belongs, and much 
 may be done in this way, in every situation 
 however destitute ; and at the present time 
 when the facilities for transporting matter of 
 all kinds, by means of railroads, are taken into 
 consideration, it may not be an unreasonable ex- 
 pectation to hope to see eventually the barren 
 hills of one district, manured and covered with 
 the alluvial deposites of others, in a high state 
 of cultivation; and then the benefits which 
 science has conferred on the community at 
 large, and which in this instance serves in 
 some degree to annihilate space, and to equalize 
 
ON SOILS. 33 
 
 the blessings which Providence has so bounti- 
 fully placed at the disposal of its creatures, 
 may in some measure be appreciated. 
 
 There are many other branches into which 
 this subject would lead us, had we the inten- 
 tion to pursue it; for instance, the character of 
 the sub-soil, whether chalk, gravel, clay, or 
 stone, are all matters of paramount importance 
 to the agriculturist. The colour also of a soil, 
 and its capabilities thereby of absorbing and re- 
 taining the rays of the sun, is another circum- 
 stance, to which perhaps too little attention is 
 paid; again, its local position, whether it lies 
 open to the genial south, or is exposed to the 
 north, should be, and is a matter of importance 
 in determining the crops, and the seasons for 
 sowing them ; and another feature is the quality 
 of the water which exists in the neighbour- 
 hood, and its influences, as well on the mea- 
 dows which it irrigates, as on the cattle and 
 stock of the farm. 
 
 All these are subjects of inquiry and of im- 
 portance, which require a careful considera- 
 tion in adapting the crops, best suited to the 
 capacity of the soil to perfect them, and we 
 may feel assured that those persons who pay 
 the greatest attention to these minutiae will be 
 amply rewarded, in the increased produce of 
 their farms, or certainly in not being disap- 
 pointed in the results they may have anti- 
 pated. 
 
CHAPTER IV. 
 
 ON THE ASSIMILATION OF MATTER BY PLANTS. 
 
 The consideration of the phenomena to 
 which this subject will give rise, extends over 
 a wide field of inquiry, and will embrace the 
 consideration of every substance, which in any 
 way either forms a part of the vegetable struc- 
 ture itself, or which serves as a means of con- 
 veying or affording such matter to plants. 
 
 In pursuing this subject, many facts may be 
 communicated to those whose attention has 
 not been turned to this inquiry, which may 
 seem almost beyond the range of credibility; 
 but as nothing will be stated which cannot be 
 vouched for, on the testimony of the first 
 authorities on such subjects, the most complete 
 reliance may be placed on the information it 
 affords ; and if, in the discussion to which this 
 article may give rise, the attention of other 
 parties, better qualified, both by their abilities 
 and the opportunities which they may have 
 of verifying the results, is called to this subject 
 much good will ensue. Truth will be elicited, 
 and society must thereby derive a substantial 
 benefit. 
 
 In the chapter on the structure of plants, it 
 has been stated that the spongelets of the roots 
 
ASSIMILATION OF MATTER BY PLANTS. 35 
 
 and the leaves, are the only means by which 
 plants can derive their supply of food. 
 
 The spongelets of the roots, taking up the 
 liquid matter which is found in the soil, and 
 the leaves absorbing the various gases, which 
 serve as a pabulum for the plant, from the 
 air. 
 
 Thus plants, in contradistinction to the ani- 
 mal tribes which exist on a mixture of solid and 
 liquid food, exist entirely on liquids, as nothing 
 can be absorbed by the root which is not in a 
 fluid state, and the gases taken up by the leaves 
 are equally fluids in a much more subtle state 
 of division. 
 
 From the most careful and recent chemical 
 analysis of the matter, forming the structure 
 of plants, it appears that all the various sub- 
 stances which enter into the composition of the 
 vegetable tribe are reducible into the four fol- 
 lowing simple gases, viz. 
 
 Carbon, 
 
 Nitrogen, 
 
 Hydrogen, 
 
 Oxygen; 
 and that these gases, combined in different pro- 
 portions, and mixed with such earthy matters 
 as potash, soda, lime, phosphorus, and magne- 
 sia, are the simple substances from which all 
 vegetable products are elaborated. 
 
 To give, therefore, such an account of the 
 means employed for this purpose, as shall 
 carry conviction on the subject, it is proposed 
 to consider each body separately, — defining 
 
i||ifl^;!piMII/lliJI|f4'>l 
 
 '!j^'^mmmmmmif 
 
 36 OF CARBON. 
 
 the source from which it is derived, the state 
 in which it exists in nature, its character and 
 general attributes. 
 
 In pursuing this plan each subject will as 
 much as possible be confined to its own limits, 
 but in some cases this will be impossible, as 
 the substances about to be considered are so 
 intimately blended the one with the other, as 
 to render a description of the one necessary to 
 the elucidation of the other. 
 
 One substance, which, although a com- 
 pound body composed of two gases, is yet, in 
 its compound state of water, so important an 
 element in the economy of plants, that the 
 changes it undergoes and the functions it per- 
 forms will be considered when speaking of 
 hydrogen, with which it is so intimately con- 
 nected, as to be incapable of separation. 
 
 OF CARBON. 
 
 Carbon, the first and prime necessary of 
 vegetable life, exists abundantly in nature in 
 three or four states. First, it is a component 
 part of the atmosphere surrounding the globe, 
 one thousand parts of which contain three 
 parts of this gas. In this state it is known as 
 carbonic acid gas, that is carbon united with 
 oxygen gas, and it is one of the most univer- 
 sally diffused substances in nature. It exists 
 in another state, as charooal, which is almost 
 pure carbon, and lastly, in the diamond, whicli 
 is pure carbon in its crystalline state. 
 
OF CARBON. 37 
 
 The difficulty here arises how to prove 
 that substances so dissimilar as carbon in the 
 gaseous state, charcoal, and the diamond, are 
 one and the same substance. To detail the 
 history of all the researches which have justi- 
 lied the first chemists in arriving at such a 
 conclusion, would be to far exceed the limits 
 of this work; this fact must be admitted, and 
 the proof that such may be the case, must 
 be demonstrated by an appeal to a substance 
 which is more familiar, and which in its 
 three states of solid, liquid, and aeriform is 
 quite as dissimilar in its appearance as the dia- 
 mond, charcoal, and carbon. 
 
 Water exists in three states, according to 
 the temperature in which it is placed. It 
 exists as steam at a high temperature, as 
 water at a medium, and as ice at a low tempe- 
 rature ; and yet who, who had not cognizance 
 that such is the case, could have believed that 
 ice and water w^ere merely modifications of 
 the same substance, or that steam was only 
 water in a different state ? So it is with car- 
 bon; an increase of temperature causes the 
 diamond itself to burn and resolve itself into 
 an aeriform state. Charcoal does the same ; 
 the only difference is, that we cannot repro- 
 duce these substances from the gaseous state, 
 with the same facility that we can reduce 
 steam to water, but still this is no argument 
 against the proposition that charcoal, carbon 
 and the diamond are the same substances, 
 produced or existing under a different form ; 
 
38 OF CARBON. 
 
 it is merely an admission of our ignorance in 
 not knowing what circumstances are neces- 
 sary for their production, or in not being 
 enabled as yet so to arrange such circum- 
 stances, so as to produce them. 
 
 In its gaseous state, as carbonic acid gas, 
 carbon is invisible, and has a sour sharp smell 
 and taste. It is destructive of all animal life, 
 not so much apparently from any noxious 
 quality it possesses as from the absence of a 
 due quantity of oxygen to support the vital 
 functions. It is constantly met with, in old 
 wells, brewers' casks, &c. and may be pro- 
 duced at pleasure by mixing a small quantity 
 of whiting or marble with strong vinegar or 
 dilute sulphuric acid, when an effervescence 
 immediately takes place, and the gas so libe- 
 rated, is tolerably pure carbonic acid gas. 
 
 The results of the ultimate analysis of va- 
 rious vegetable substances is here given, that 
 it may be seen how important a part in the 
 vegetable economy carbon performs, and that 
 the importance attached to it, in this work, is 
 not overrated ; and it must be here impressed 
 forcibly on the reader, that no substance what- 
 ever can be produced in plants unless the ele- 
 ments composing it are present, and that al- 
 though plants possess the power of decom- 
 posing one substance, and combining one of its 
 component parts with another substance, or in 
 different proportions with the same matter it 
 was previously combined with, and thereby 
 producing a new compound differing materially 
 
OP CARBON. 39^. 
 
 from its original state ; still that they have not 
 the power of creating new matter, and that all 
 the products of plants are derived from the 
 absorption of their component parts, from the 
 atmosphere, or by the roots, or from the decom- 
 position of other matter in the structure of the 
 plant itself. This fact cannot be too much 
 impressed on the mind, and all the subsequent 
 reasoning herein contained will depend upon 
 this acknowledged truth. 
 
 The ultimate analysis of sugar, a vegetable 
 product of the most useful kind, in its in- 
 fluence on the comforts and luxuries of life, as 
 widely diffused in the vegetable world as it is 
 useful, consists of. 
 
 Carbon 43 parts,* 
 
 Water 57 parts. 
 The better the sugar the larger the quantity 
 of carbon. Hence the trade distinction of 
 high and low sugars, the former containing 
 a large quantity of saccharine matter, and 
 being in every respect a better article than the 
 latter. 
 
 The analysis of starch, another vegetable 
 product almost equally diffused, consists of 
 
 Carbon 38 parts,*. 
 
 Water 62 parts. 
 The analysis of gum which exists in the 
 farina of all seeds, and frequently exudes 
 from the bark of trees which have received 
 any injury, consists of 
 
 Carbon 36 parts,* 
 
 Water 64 parts. .^iutiiu 
 
 * Henry. 
 
n.y||L|j iiiii.yiijiflwppippw'; 
 
 4# 
 
 OF CARBON. 
 
 Woody fibre contains 38 per cent of carbo;i, 
 
 Meadow hay contains 44 per cent of carbon.* 
 
 Tlie analysis of vegetable oils, such as olive 
 or linseed oil yields carbon 77 parts. 
 
 In all these analyses water is stated instead 
 of its component parts of oxygen and hydro- 
 gen, this is done to simplify the subject under 
 consideration; but the analysis of water will 
 be considered in its due and proper place. 
 
 From these results it must be apparent that 
 a due supply of carbon is absolutely necessary 
 to vegetable life, and to enable plants to create 
 such substances as sugar, starch, mucilage and 
 oils. From whence that supply is obtained 
 will now form the next subject for our conside- 
 ration. 
 
 " Vegetable physiologists have hitherto con- 
 sidered the fertility of every soil to depend on 
 the presence of a substance called humus. This 
 substance, hitherto recognised as the nutriment 
 of plants and believed to be extracted by them 
 from the soil in which they grow, is itself the 
 product of the decay of other plants." 
 
 " It has been called by a variety of names, 
 such as humus, humic acid, coal of humus, &c. 
 according to the external characters each spe- 
 cies has presented, and hitherto the opinion, 
 that this substance humus is united in some 
 way or other with the carbon, has been so pre- 
 valent as to seem to require no argument in its 
 favour." 
 
 "The obvious difference in the growth of 
 plants, according as the soil contained a greater 
 
 * Liebig. 
 
OF CARBON* 41 
 
 or lesser quantity of this substance, seemed to 
 afford incontestable proof of its correctness."* 
 
 Yet this position is found to be untenable, 
 and conclusive proofs will be offered to show 
 that humus of itself does not enter into the 
 composition of any plant, or afford them the 
 smallest nourishment. 
 
 It has been already noticed, in considering 
 the structureand functions of vegetables, that 
 the roots, the only source by which humus or 
 humic acid could be introduced into plants, 
 can only absorb nourishaient in the shape of a 
 liquid, and if it can be proved that the sub- 
 stance now under consideration, humus, is in- 
 soluble in water, it must be at once admitted 
 that it cannot perform the ofHce hitherto as- 
 cribed to it, and that search must be made 
 elsewhere for the pabulum of plants. 
 
 It has been demonstrated by Sprugel, a Ger- 
 man chemist, that humic acid is only soluble 
 in 2500 times its weight of water, and even to 
 possess this degree of solubility it must be 
 acted on by the water as soon as it is formed 
 from the humus, and that it forms compounds 
 with potash, soda, lime and magnesia, but none 
 of which possess a greater degree of solubility 
 than the humus itself And it has been farther 
 demonstrated that if by any chance it should 
 become dry by exposure to the atmosphere, or 
 be subjected to a temperature lower than 32° 
 
 * Almost all the arguments in favour of the theory here 
 promulgated are taken from Professor Liebig's work before 
 noticed, and in some cases the exact words of the translation 
 are quoted. 
 6 
 
4^ OF CARBON. 
 
 that it becomes and remains perfectly insolu- 
 ble in water under any circumstances. 
 
 These facts, which demonstrate plainly that 
 humus, or humic acid, cannot enter into the 
 composition of plants, have not been overlooked 
 by vegetable physiologists ; but they have sup- 
 posed, that, under certain circumstances, the 
 alkaline earths might act upon the humus, and 
 render it soluble, and thus in a fit state for the 
 assimilation of plants; but by calculations 
 made by the author of the work before quoted,* 
 it is proved beyond all question, that even sup- 
 posing humus in its most soluble compound, 
 that is as a humate of lime, to be absorbed by 
 plants, still that the produce of a given field so 
 far exceeds the quantity of humate of lime, 
 that could by any possibility either exist or be 
 created on such a field, under the most favour- 
 able circumstances, that some other cause must 
 be assigned for the source of nutrition to plants. 
 
 Another argument that is conclusive on the 
 subject of humus not forming the nutrition of 
 plants is, that as humus is the result of the de- 
 cay of vegetable matter, from whence did the 
 first vegetables derive their supply of this sup- 
 posed necessary substance? 
 
 We have seen in the analysis of hay that 
 100 parts consist of 44 parts carbon. Hence 
 the produce of an acre, weighing one ton must 
 contain about 985 pounds of carbon. An acre 
 of wheat also, yielding eight sacks, and weigh- 
 ing 2000lbs., must produce about 600lbs. of 
 
 * Sprugel. 
 
OF CARBON. 43 
 
 carbon, exclusive of that contained in the straw 
 and roots. Again we have seen that woody 
 fibre contains 38 per cent, of carbon, and wood 
 in its growth continues to assimilate this quan- 
 tity annually for a long series of years, in the 
 production of timber. The question therefore 
 that now arises is, from whence do these or- 
 ganic substances derive their supply of this 
 article? In the case of the hay and the wheat- 
 field, it may be argued that the manure applied 
 to the land furnishes this supply ; but then, 
 it may be asked, whence does the water mea- 
 dow, and the forest derive this supply, seeing 
 that in neither case is any manure applied for 
 many years together, and yet the produce of 
 vegetable matter is equally great. 
 
 It is not intended by this argument to deny 
 the benefit that manures do to the soil, and it 
 will be seen in the sequel, the importance at- 
 tached to them. But here the question is from 
 whence is the "supply of carbon obtained ? and 
 it may be positively affirmed, that the manure 
 applied in any case to the land, does not afford 
 a sufficient quantity of this substance to ac- 
 count for the immense quantity existing in the 
 produce of the land. The answer to this ques- 
 tion embraces a considerable field of inquiry, 
 and one which when fully considered, will 
 open our minds to the great and wonderful 
 powers of nature, in the means employed for 
 equalizing matter, and restoring and keeping 
 up the harmony that should and does exist in 
 all parts of the vast scheme of the creation, and 
 one which cannot fail to impress us with the 
 
miw 
 
 44 OP CARBON. 
 
 omnipotence of that Almighty being, who, for 
 purposes far beyond our finite comprehensions, 
 has placed man at the head of this scheme, in- 
 dued with power to use these influences for his 
 own good, and with necessities which compel 
 their action. 
 
 It has previously been stated, that carbon 
 exists as a gas in the atmosphere which sur- 
 rounds the globe, and although its quantity 
 may appear too limited to produce the effects 
 attributed to it, still when the immense extent 
 of the atmosphere which surrounds the globe is 
 taken into consideration, and the constant sup- 
 ply of carbon which is furnished by mankind 
 and all animals in the process of respiration, 
 and the quantity that is yielded in the process 
 of combustion, our wonder will cease, and .will 
 be directed to that principle of vegetable life 
 which can absorb such a vast amount of nox- 
 ious matter. 
 
 In addition to the carbon, 100 parts of the 
 atmosphere which surrounds the globe, con- 
 sists (in every climate, and in every situation) 
 of 21 parts of oxygen gas, and 79 parts of ni- 
 trogen. Here we have only to speak of oxy- 
 gen, and the consideration of nitrogen and 
 its effects on vegetation, must be postponed* to 
 a succeeding chapter. 
 
 Oxygen is the great supporter of animal 
 life during the process of respiration. In this 
 process the atmospheric air is taken into the 
 lungs, and one portion of the oxygen it contains 
 is absorbed by the blood, and another unites 
 with the carbon of the blood brought up by the 
 
OF CARBON. 45 
 
 veins in their return to the heart from different 
 parts of the body, and is exhaled in the state 
 of carbonic acid gas; and this gas so exhaled, 
 is, of course, unfit for respiration until the car- 
 bon it contains is absorbed in some way or 
 other from the oxygen. 
 
 Now it is calculated* that a man consumes 
 every day, in the usual course of respiration, 
 45,000 cubic inches of oxygen gas ; that a thou- 
 sand millions of men consume in one year 
 rffVo of all the oxygen that exists in the atmo- 
 sphere: and hence, in the course of time, all 
 this gas, the prime necessary of life, would be 
 entirely consumed, if some corrective power 
 did not exist to neutralize this effect. For this 
 power we must look to plants. It has been ex- 
 plained that the gas exhaled from the lungs of 
 all animals is carbonic acid gas — that is, car- 
 l)on combined with oxygen — and we are now 
 ill a position to prove that plants absorb all this 
 carbonic acid gas. That they assimilate the 
 carbon to themselves, and give up the oxygen 
 in a pure state again to support animal life, 
 and again to enter into the state of carbonic 
 acid, and again to be purified in the vegetable 
 structure, and thus to perform its office in an 
 unceasing round of useful operations. 
 
 In the calculations here submitted, all notice 
 of the quantity of carbon emitted by animals, 
 or in the process of combustion is omitted — 
 and yet these sources supply a quantity of 
 carbon considerably greater than those we have 
 
 * Lfebig. 
 
 5* 
 
46 OF CARBON. 
 
 instanced : however, it is enough for the pur- 
 pose proposed, and it only remains to prove 
 that the purification of such effluvia is the of- 
 fice performed by plants. 
 
 This peculiar property of the vegetable tribe 
 is so easy of demonstration that every one may 
 convince himself of its existence with very lit- 
 tle trouble. 
 
 The leaves and green parts of plants absorb 
 carbonic acid gas, and give off an equal volume 
 of oxygen, and this they do quite indepen- 
 dently of the plant itself. For instance, if the 
 stem of a plant is placed in water containing 
 carbonic acid gas, and in this state exposed to 
 the sun's rays, the carbonic acid is found to 
 have entirely disappeared from the water, and 
 if the experiment has been conducted under a 
 glass receiver filled with w^ater, an equal bulk 
 of oxygen gas will be found to have been 
 emitted, and when no more gas is given off, it 
 is a sign that all the carbonic acid gas is de- 
 composed, but the process immediately recom- 
 mences if a new portion of it is added. 
 
 The experiments of De Saussine farther 
 prove that plants increase in weight during 
 this decomposition, but in a greater proportion 
 than can be accounted for by the assimilation 
 of carbon alone; and hence it is referred that 
 hydrogen, one of the elements of water, is assi- 
 milated at the same time, and thus a new source 
 of oxygen arises to supply the loss the air is 
 constantly suffering. 
 
 This simple experiment incontestably proves 
 that carbon is assimilated by the leaves of 
 
OF CARBON. 47 
 
 plants and explains the means nature employs 
 for purifying tne atmosphere of such an amount 
 of noxious matter. The proofs might here be 
 multiplied that such is the case, but the one 
 stated is so easy of comprehension, and so 
 readily exhibited, that it is useless to do so. 
 
 It will be explained farther that the roots 
 also absorb a portion of carbon, which is 
 equally assimilated by the plant, and thus per- 
 form their part in this attribute of the vegeta- 
 ble tribe, but as the carbon so absorbed must 
 be dissolved in water, its consideration will be 
 considered under that head. 
 
 Another source of carbon to plants arises 
 from vegetable matter in a state of decay. 
 Decay is only another word in chemistry, for 
 the slow process of combustion, where in the 
 plants are acted on by the oxygen of the at- 
 mosphere, and give off the carbon they had 
 assimilated during life, in union with a por- 
 tion of the oxygen in the state indeed of car- 
 bonic acid. 
 
 All decaying vegetable matter under favour- 
 able circumstances as to moisture, tempera- 
 ture, &c. is surrounded by an atmosphere of 
 this carbonic acid gas, formed at the expense 
 of the oxygen of the atmosphere, and as this 
 process is carried on equally well in a soil 
 permeable to the air, as in the air itself, it is a 
 continued source of carbonic acid gas, which 
 it emits very slowly, and which is thus en- 
 abled to be absorbed by plants growing near it. 
 
 In the early stages of vegetable life, before 
 any leaves are formed, and when consequently 
 
4S OF CARBON. 
 
 the plant possesses no organs for absorbing, 
 the carbonic acid from the atmosphere, the 
 substance of the seed itself, as before stated, 
 furnishes the necessary pabulum for the for- 
 mation of the root, which once formed imme- 
 diately performs the functions of the leaves as 
 well as root, by absorbing the carbonic acid 
 gas given off by the surrounding decaying 
 vegetable matter, as well as moisture, and the 
 other ingredients of the soil; and as the leaves 
 and other parts of the plant are developed, 
 nutrition is derived by the plant both from the 
 roots and the organs above the ground, and in 
 this stage it advances rapidly to maturity, but 
 when the plant is quite matured and the organs 
 by which it derives its supply of food from the 
 atmosphere are quite perfected, the carbonic 
 acid gas of the soil is no longer required. De- 
 ficiency of moisture does not now arrest the 
 progress of the plant, provided it is enabled to 
 derive from the atmosphere and dews suffi- 
 cient for the purposes of assimilation, and car- 
 bon during the heats of summer is derived ex- 
 clusively from the atmosphere. 
 
 When the supply of food to a plant is greater 
 than it requires for the development of its or- 
 gans already existing, the superfluous nutri- 
 ment is not returned to the soil, but is em- 
 ployed by the plant in the formation of new 
 organs and in increased luxuriance. At the 
 side of a cell already formed, a new cell arises, 
 at the side of a branch and leaf a new branch 
 and leaf are developed, and these new forma- 
 tions owe their existence entirely to an excess 
 
OF CARBON. 49 
 
 of nourishment. The power of absorbing nu- 
 triment therefore from the atmosphere, with 
 which the leaves of plants are endowed, being 
 proportionate to the extent of this surface, 
 every increase in the size and number of those 
 parts is necessarily attended with an increase 
 of power, and, in consequence, to a certain ex- 
 tent, farther development of new leaves and 
 branches. 
 
 This process is continually in operation ; it 
 comaiences with the first formation of the leaf 
 and does not cease with its perfect development; 
 but the matters derived from the continued 
 assimilation by the perfect leaves are no longer 
 employed in their own increase, they now 
 serve for the formation of woody fibre, sugar, 
 starch, &c. in the ripening of the fruit, when 
 the functions of the leaves of most plants 
 cease, because the products of their action are 
 no longer required, and they then yield to the 
 action of the atmosphere, change their colour 
 and fall off, or, as in annuals, they partake of 
 the general decay of the whole plant. 
 
 A vast deal of controversy has taken place, 
 on the subject of the absorption of carbonic 
 acid gas by plants, by authors of considerable 
 ability on both sides; but the details here intro- 
 duced, are, it is imagined, sufficient to prove, 
 both by direct and collateral arguments, that 
 the view now taken is correct, and it is gene- 
 rally admitted to be so by the most eminent 
 physiologists of the present day. It will be 
 desirable however to continue the subject far- 
 ther, and detail some of the experiments made 
 
^mmmm^^m^ 
 
 50 OF CARBON. 
 
 with a view to prove that carbon did not form 
 the pabulum of plants. The circumstances 
 also under which plants yield carbon to the 
 atmosphere instead of absorbing it, must be 
 explained, and in doing so, a very nice, but at 
 the same time a perfectly clear and lucid dis- 
 tinction between the chemical transformations 
 and mechanical operations carried on by plants 
 will have to be considered. 
 
 With a view to determine whether carbon 
 actually formed the principal nutrition of vege- 
 table life, seeds have been planted in fine mar- 
 ble reduced to powder, and in flowers of sul- 
 phur, and watered with water containing 
 carbonic acid gas in solution. Under these 
 circumstances, the seeds have generated and 
 lived to produce two or three leaves, but never 
 more, and in all cases the plant has then died : 
 and such experiments as these have been ad- 
 duced as conclusive evidence that carbon does 
 not form the nutriment of plants; but the par- 
 ties making these experiments have either been 
 willingly or culpably negligent in arriving at 
 this conclusion from such data. 
 
 It will be seen as we proceed that many con- 
 ditions are necessary for the life and develop- 
 ment of the organs of plants, and that it is not 
 enough that one element forming it is admitted, 
 the principal nutriment should be present, but 
 the combined action of all is necessary. 
 
 The organs of plants as well as of animals, 
 consist of a variety of substances, some re- 
 quiring carbon, others nitrogen, others again 
 hydrogen, and all the presence of metallic ox- 
 
OF CARBON. 51 
 
 ides and earthy salts, for their perfection. Is 
 it to be expected, therefore, that when only one 
 of these necessaries is present, that a healthy 
 and vigorous plant is to be the result, or that 
 because such plants did not succeed, that the 
 element spoken of forms no part in the vege- 
 table economy? Certainly not, and the manner 
 in which these experiments were conducted is 
 opposed to all the rules of philosophical inquiry, 
 and to all the laws of modern chemistry. 
 
 The other objection which has been taken 
 to the assimilation of carbon by plants has 
 arisen from the fact, that under certain circum- 
 stances plants give off carbonic acid gas instead 
 of assimilating it. In the chapter on the func- 
 tions of plants it has been explained that light 
 is an essential to the process of the assimilation 
 of carbon, and that the decomposition of carbo- 
 nic acid is arrested by darkness. But then, 
 namely at night, a true chemical action of the 
 oxygen of the atmosphere commences on the 
 leaves and other parts of the plant. This pro- 
 cess is not at all connected with the life of the 
 plant, as it acts in a similar way on the dead 
 plant; indeed, this result must not be consi- 
 dered in any way as the act of the plant itself, 
 but as the effect of the oxygen of the atmo- 
 sphere acting on the plant at a time when its 
 own powers of assimilation are in abeyance; 
 and yet, notwithstanding these adverse circum- 
 stances, it will be demonstrated still that plants 
 absorb more carbon during the day than is 
 given off by them during the night, and that in 
 regarding them as the great purifyers of the at- 
 
62 OF CARBON. 
 
 mospbere of the carbon exbaled by all animals, 
 their proper attribute is only assigned to them. 
 
 A soil in which plants vegetate vigorously 
 contains moisture, which is indispensably 
 necessary to their existence. Carbonic acid 
 also is always present in such a soil, whether 
 it has been abstracted from the air, or gene- 
 rated by the decay (as before explained) of 
 vegetable matter, and water also, from what- 
 ever source in nature it is derived, invariably 
 contains carbonic acid gas. 
 
 Plants during their life possess the power 
 of absorbing, by the spongelets of the roots, 
 moisture, and this moisture contains carbonic 
 acid gas, derived from either of the sources 
 above described. Is it therefore surprising 
 that plants should again give off this carbonic 
 acid, when light, the power which enabled the 
 plant to decompose and assimilate this carbon, 
 is absent ? 
 
 Carbonic acid thus absorbed by the roots is 
 dissolved in the sap which pervades all 
 parts of the plant, and evaporates every 
 moment through the leaves with the water, in 
 quantity corresponding to such evaporation. 
 
 *' Neither this emission of carbonic acid nor 
 the absorption of oxygen has any ccmnexion 
 with the process of assimilation. The former 
 is a mechanical, the latter purely a chemical 
 process." If this view of the subject is correct, 
 those plants which require the presence of 
 oxygen to convert their volatile constituents 
 into resins, should absorb the most when the 
 influence of the light is withdrawn, and such 
 
ON CARBON. 53 
 
 we find to be the case, for while the tasteless 
 leaves of the American aloe absorb only 0.3 of 
 their bulk of oxygen during the dark, the 
 leaves of some of the fir tribe which contain 
 volatile and resinous oils absorb ten times and 
 the leaves of the oak containing tannic acid, 
 fourteen times that quantity. 
 
 This chemical action is shown also very 
 plainly in the leaves of the Cacalia ficoides 
 and others, which are sour in the morning 
 from the absorption of oxygen during the 
 night, tasteless at noon from the assimilation 
 of carbon during the sun's light, and bitter in 
 the evening, w^hen in addition to the carbon a 
 portion of the hydrogen of the water, a com- 
 ponent part of all bitter substances, has been 
 assimilated. 
 
 Indeed the quantity of oxygen absorbed can 
 be estimated pretty nearly by the length of 
 time which the green leaves of plants require 
 to undergo an alteration in colour, by the in- 
 fluence of the atmosphere. Those which con- 
 tinue longest green will abstract less oxygen 
 from the air, than those which change colour 
 more rapidly. 
 
 Thus the leaves of the beech and poplar 
 absorb eight or nine times their bulk of oxygen 
 in the same time that others, whose durability 
 as to colour is greater, absorb only two or three 
 times that quantity, and when these leaves are 
 dried, in the dark, in the vacuum of an air 
 pump, moistened with water and placed in a 
 vessel filled with oxygen, they are found to 
 change colour exactly in the proportion in 
 6 
 
54 ON CARBON. 
 
 which the gas is absorbed. The chemical 
 nature of this process is thus completely esta- 
 blished. 
 
 There are other facts which prove in a de- 
 cisive manner that plants yield more oxygen 
 to the atmosphere than they consume, but 
 these proofs must be drawn from those plants 
 which live under water. 
 
 '' When pools and ditches, the bottoms of 
 which are covered with plants, freeze on their 
 surface in winter, so that the water is com- 
 pletely excluded from the air by a stratum of 
 ice, small bubbles of gas are observed to escape 
 continually during the day from the points of 
 the leaves and twigs. These bubbles are seen 
 most distinctly during the day when the sun's 
 rays fall on the ice, they are very small at 
 first, but eventually form large bubbles. These 
 consist of pure oxygen gas, and neither during 
 the night nor during the day even, when the 
 sun does not shine, are they observed to dimi- 
 nish in quantity. The source of this oxygen 
 is the decomposition of the carbonic acid gas 
 by the plant, the carbon of which is assimilated, 
 and the oxygen evolved, and the water is again 
 supplied with carbonic acid by the continuous 
 decay of vegetable substances contained in the 
 soil." 
 
 The principal sources of carbon, and the 
 manner in which it is assimilated by plants in 
 the beautiful system of nature have now been 
 considered, and yet many questions may arise 
 respecting it; one of the most obvious is, that 
 if plants are intended by nature to perform the 
 
ON CARBON. 55 
 
 functions here described and to be the puri- 
 fyers of the atmosphere, how can it be ex- 
 plained that a larger proportion of carbonic acid 
 does not exist in the atmosphere during the 
 winter, when vegetation is completely torpid, 
 than in the summer; seeing that in the one 
 case every source for the supply of carbon 
 exists in excess, and in the other that all the 
 sources for the supply of oxygen are in abey- 
 ance ? 
 
 " This would certainly form a cogent argu- 
 ment did we not look on the whole field of cre- 
 ation at once. The proper, constant, and in- 
 exhaustible sources of oxygen gas are the 
 tropics and warm climates; w^here a sky, sel- 
 dom clouded, permits the sun to shine upon an 
 immeasurably luxuriant vegetation. The tem- 
 perate and cold zones must on the contrary pro- 
 duce a superabundance of carbonic acid, which 
 serves as a supply to the tropical plants, and the 
 same current of air which in its constant pas- 
 sage from the equator to the poles, brings with 
 it a supply of oxygen, also takes away the ex- 
 cess of carbon, and thus equalizes the bless- 
 ings of a pure air to the whole earth." 
 
 Thus plants not only afford the means of 
 nutrition to all animals, but they likewise per- 
 form an important part in the creation in puri- 
 fying the atmosphere from all noxious matter, 
 and furnishing an inexhaustible source of pure 
 oxygen. 
 
 Animals, on the contrary, consume the oxy- 
 gen and expire the carbon, which furnishes 
 
5d ON NITROGEN. 
 
 nutrition to plants ; and thus the medium in 
 which both exist, namely, the atmosphere, is 
 maintained constantly unchanged. 
 
 " The presence of a rich and luxuriant ve- 
 getation may be conceived without the pre- 
 sence of animal life. But the existence of 
 animal life, constituted as we now are, is un- 
 doubtedly dependant on vegetable life for its 
 support;'^ but both are interwoven in such a 
 manner as to call forth our highest expression 
 of admiration of the system, and devotional 
 feelings of gratitude to the Being who has so 
 constituted this scheme, and who has given to 
 man the power in some measure to compre- 
 hend its perfections. 
 
 ON NITROGEN. 
 
 Nitrogen, the next in order and in necessity 
 for the development of plants, is only known 
 in its gaseous state, or in combination with 
 other gases in a fluid or solid state, as in ni- 
 tric acid and salammoniac, or combined with 
 salts in a solid form, such as nitrate of potash, 
 &c. 
 
 Nitrogen also forms the great bulk of the 
 atmosphere surrounding the earth, 100 parts 
 containing 79 parts nitrogen, and 21 oxygen; 
 and it is remarkable, that although these 
 gases possess very different specific gravities, 
 that the atmosphere under all circumstances 
 is composed of exactly these proportions, 
 
ON NITROGEN. 67 
 
 united with the portion of carbon before no- 
 ticed, bat which need not here be farther 
 discussed. 
 
 It appears to possess of itself a negative 
 effect on the animal frame ; its only use being 
 apparently to dilute the oxygen: but in the 
 vegetable economy its functions are far more 
 important, as it enters into combination with 
 many other substances composing the struc- 
 ture, and is itself assimilated, and constitutes 
 the most nutritious part of plants. 
 
 It differs, however, materially from carbon, 
 the subject of the last section, in this respect, 
 that it is never absorbed by the leaves, or the 
 green parts of plants ; its only access is by the 
 roots in a fluid state : and this, therefore, will 
 simplify materially the consideration of this 
 substance. 
 
 It is to the presence of this gas, assimilated 
 and combined, in the farina of wheat, oats, 
 barley, &c., as well as in the flesh of animals, 
 that the nutritive qualities of these substances 
 are to be attributed, and in proportioK as this 
 gaseous body is present in each case so is the 
 nourishment the food contains. 
 
 The form in which nitrogen generally pre- 
 sents itself to our senses is in combination 
 with hydrogen, (one volume of the former 
 combining with three volumes of the latter) 
 and in this state it is known as ammonia; this 
 substance again combines with carbonic acid 
 gas, and forms carbonate of ammonia, one of 
 the most universally diffused substances in 
 
 6 * 
 
58 ON NITROGEN. 
 
 nature, and one, as this article will demon- 
 strate, of the most vital importance in the 
 economy of animal and vegetable life. The 
 process by which vegetables have the power 
 of forming this compound, and the sources 
 from which it is obtained, will now form the 
 subject for our consideration. 
 
 The portion of farinaceous matter in which 
 the nutriment resides, is what is termed the 
 gluten, and it may be easily prepared from 
 wheat flour, by mixing it into a paste, and 
 washing it constantly with water until the 
 water runs away quite transparent. The pure 
 gluten then remains, and when dried, it some- 
 what resembles glue, and is in every respect 
 perfectly analogous to animal gluten. 
 
 This substance has never yet been analyzed 
 with a view to obtain its ultimate constituents; 
 but Dr. Henry, in speaking of it, says, " It 
 closely resembles animal gluten, especially in 
 the large quantity of nitrogen which enters into 
 its composition." It may here be stated that 
 the value and weight of wheat, and all grain 
 depends on the quantity of gluten it contains, 
 the best wheats containing the greatest quan- 
 tity of gluten, and the smallest quantity of 
 starch ; its weight and value as an article of 
 food, depending on the relative proportion of 
 the two ingredients. 
 
 The following tables prepared by Sir H. 
 Davy, give the result of an analysis of various 
 kinds of corn, and they may in some degree as- 
 
ORIGIN AND ASSIMILATION OF NITROGEN. 59 
 
 sist the agriculturist in forming a judgment on 
 the quality of the seed to be sown : — 
 
 starch. Gluten. 
 
 n 
 
 19 
 
 70 
 
 24 
 
 74 
 
 23 
 
 75 
 
 21 
 
 79 
 
 6 
 
 6 
 
 5 
 
 100 parts of full grained wheat sown in 
 
 the autumn yielded 
 100 parts of wheat sown in the spring 
 100 parts of Barbary wheat . 
 1 00 parts of Sicilian wheat . 
 1 00 parts of full and fair Norfolk barley 
 100 parts of Suffolk rye 
 
 ON THE ORIGIN AND ASSIMILATION OF NITROGEN. 
 
 The analysis above given must amply de- 
 monstrate the fact, that nitrogen exists in the 
 most valuable part of the vegetable structure, 
 viz. the seeds. The first and most important 
 question therefore is, how and in what form 
 does nature furnish nitrogen to the various 
 parts of plants? 
 
 There is not the slightest reason for be- 
 lieving that the nitrogen of the atmosphere in 
 its simple state, takes any part in the process 
 of assimilation in plants or animals; on the con- 
 trary, it is known that many plants emit the 
 nitrogen which is absorbed by the roots, either 
 in its gaseous state, or as atmospheric air dis- 
 solved in water. And also, it must be stated, 
 that the nitrogen of the atmosphere cannot by 
 any known chemical process be made to unite 
 with any other gas than oxygen. But it is also 
 known that nitrogen united with hydrogen and 
 
60 ORIGIN AND 
 
 thus forming ammonia, enters largely into the 
 composition of vegetable gluten, and that this 
 compound is invariably evolved in the decom- 
 position of animal matter. 
 
 Ammonia is farther the simplest of all the 
 compounds of nitrogen and hydrogen, and un- 
 der all circumstances, when these two gases 
 are disengaged in contact, the one with the 
 other, they unite together to form ammonia. 
 
 As all animal matter consists principally of 
 nitrogen, it must therefore in its decay yield it 
 again (combined with hydrogen in the state 
 of ammonia) to the atmosphere, and when the 
 vast amount of animal matter which is con- 
 stantly in a state of decay is considered, our 
 wonder at the source of its supply will cease. 
 
 The ammonia thus liberated or formed by 
 the decomposition of animal matter enters the 
 atmosphere in a gaseous state, which com- 
 bining with the carbonic acid gas, which, as 
 exemplified in the preceding chapter exists 
 also abundantly in the air, forms carbonate of 
 ammonia. 
 
 Ammonia in its gaseous form, as well as in 
 all its compounds with carbon, is exceedingly 
 soluble in water; hence, it cannot long remain 
 in the atmosphere, but must be dissolved and 
 carried into the earth by the first rain which 
 falls after it is evolved. — Hence also rain water 
 must at all times contain ammonia, though 
 not always in equal quantities. It must be 
 greater in summer than in winter, from the 
 double cause, that the showers are more rare 
 in the former case than in the latter, and also 
 
ASSIMILATION OF NITROGEN. 61 
 
 that the decay of all animal matter takes place 
 with greater rapidity during the increased 
 heats of summer, and it may be that to this 
 cause is to be attributed the grateful feeling of 
 the purity and freshness of the air which can- 
 not fail to have struck even the most insensi- 
 ble, when a long summer's drought is termi- 
 nated by a refreshing shower. 
 
 The author before quoted,* and whose work 
 is again recommended to all who wish to mas- 
 ter the subject under consideration, here enters 
 into a variety of calculations to prove the ex- 
 tent to which ammonia exists in the atmosphere. 
 It is hardly necessary for us here to follow all 
 the details he gives, but the result may be ac- 
 ceptable. 
 
 It is calculated that if a pound of rain water 
 contains only the fourth part of a grain of am- 
 monia, and this is a low calculation, then that 
 a field containing 40,000 square feet, would 
 receive 80lbs. of ammonia annually, presuming 
 that the fall of rain over such a surface 
 amounted to 2,500,000 pounds, the quantity 
 which on an average usually falls on such a 
 space. This is a larger quantity of nitrogen 
 than would be required by a crop of copse 
 wood, hay or turnips; but less than a field of 
 corn including the straw and roots, contain; 
 and it must here be stated, that although this 
 quantity of ammonia would be dissolved in the 
 rain that may fall, still some portion of it would 
 again enter the atmosphere with the water 
 
 * Liebig. 
 
62 .ORIGIN AND 
 
 which might be evaporated, and also that the 
 ammonia which is thus abstracted from the at- 
 mosphere, would as constantly be supplied by 
 the decay of animal matter. 
 
 The ammonia thus dissolved and carried me- 
 chanically into the earth, is then absorbed by 
 the spongelets of the roots, and in the course of 
 its assimilation by the plant, enters into com- 
 bination in a variety of ways, forming the vari- 
 ous substances containing nitrogen, such as 
 albumen, gluten, quinine, &c. into all of which 
 it is known to enter from the ultimate analysis 
 to which they have been subjected. It now only 
 remains to be considered, as far as proving the 
 presence of ammonia is required, whether plants 
 in the various processes to which they are sub- 
 jected to render them useful to mankind, ever 
 give off ammonia; if it be found they do, the 
 proof will be regarded as certain, and the other 
 circumstances connected with nitrogen will 
 at once be discussed. 
 
 It is accordingly found that the juices of the 
 maple tree and the birch, when mixed with 
 lime, which decomposes the compound contain- 
 ing the ammonia in such juices, emit a strong 
 smell of ammonia, and in the manufactory of 
 sugar from the beet-root, such a quantity of 
 ammonia is given off, as to strike everyone who 
 has ever entered such an establishment, and the 
 products also of all medicinal herbs, whether 
 produced by distillation or consisting of extrac- 
 tive matter, yield ammonia during such process- 
 es. The sap also which exudes from the vine 
 when cut, being first mixed with muriatic acid 
 
ASSIMILATION OF NITROGEN. 63 
 
 and then with lime, gives off ammonia in its 
 free state. 
 
 All these examples must convince even the 
 most skeptical that ammonia does exist in al- 
 most all plants. 
 
 Hitherto the presence of ammonia in the at* 
 mosphere only has been considered, but we 
 shall now enter into detail rather more fully, 
 as to the sources from whence the atmosphere 
 derives its supply. 
 
 In the analysis before given it has been seen 
 that the muscle or flesh of all animals is com- 
 posed almost entirely of nitrogen, and that an- 
 imal matter in its decay, always yields this sub- 
 stance in the form of ammonia; hence, if w^e 
 reflect that a generation of a thousand millions 
 of men is renewed every thirty years, and that 
 in the same period thousands of millions of ani- 
 mals cease to live and are reproduced, the ques- 
 tion will then arise, what becomes of the ammo- 
 nia which mustbe generated by their decay? But 
 the examination of this subject must be carried 
 still farther, to show that the liquid excrement 
 of all animals, and especially of those which are 
 carnivorous, contains an excess of ammonia, in 
 the state most useful for the assimilation of the 
 plant, and in that state also in which it may 
 most readily be applied and collected by agri- 
 culturists, for use as a manure. 
 
 It is desirable here to explain why it is that 
 the liquid excrement, that is the urine of all 
 carnivorous animals, is richer in this principle 
 of ammonia than that of herbiferous animals. 
 It has been previously noticed that flesh con- 
 
64 ORIGIN AND 
 
 sists almost entirely of nitrogen. Those anin als 
 therefore which exist on the flesh of other ani- 
 mals consume a much larger quantity of this 
 nitrogea, than those which exist on vegetables 
 alone, and the system of the former not re- 
 quiring all the nitrogen for its support, the excess 
 must be carried off by the natural vents, and 
 accordingly it is found that in proportion as the 
 animal is either carnivorous or otherwise, so is 
 the urine rich in ammonia; and farther it is re- 
 marked that amongst herbiferous animals, in 
 proportion as the food is rich in nitrogen, (and it 
 has been shown that wheat and all grains con- 
 tain that principle) so will be the contents of 
 the urine. 
 
 Acting on this principle then, it is found that 
 100 parts of wheat grown on a field manured 
 with cow-dung, (manure containing the small- 
 est portion of ammonia) yielded on its analysis 
 only 12 parts of gluten, whereaslOO parts grown 
 on the same field, but manured with human 
 urine (the manure containing the largest quan- 
 tity of ammonia) yielded the maximum of 
 gluten, viz. 35 parts.* 
 
 From this it will be seen that it is perfectly 
 within the power of the agriculturist to make 
 his crops nutritious or otherwise. 
 
 If manured with urine or with other ma- 
 nures, which will furnish a supply of this most 
 important ingredient, the grain will be nutri- 
 tious and heavy. If on the contrary this pabu- 
 lum is not supplied to the growing crop, the 
 
 *Liebig. 
 
ASSIMILATION OF NITROGEN. 65 
 
 grain may be equally large, but it will weigh 
 lighter and be less nutritious. The agriculturist, 
 therefore, has it in his power to grow his crops, 
 his wheat especially, to suit his customers; for 
 example, if he lives in the vicinity of a starch 
 manufactory, where his wheat may be required 
 for the purpose of making that article, it will 
 be the more valuable, the less nitrogen and the 
 more carbon it contains, but if required as an 
 article of food, or for making vermicelli, the 
 very reverse of this is the case, an abundant 
 supply of nitrogen being the requisite to give 
 it that quantity of gluten on which its value as 
 an article of food entirely depends. 
 
 These results may be obtained from the same 
 seed and the same soil, wholly by the applica- 
 tion of the proper manures, viz. of decaying 
 vegetable matter, in the one case to furnish a 
 due supply of carbon for the wheat intended for 
 the starch-maker, and of urine or the nitrates 
 of soda or potash in the other case to supply the 
 gluten for the miller. 
 
 These subjects will again come under our 
 notice under the subject of manures. We now 
 proceed to point out other matters connected 
 with the supply of nitrogen or ammonia to the 
 soil. 
 
 The solid excrement of animals contains com- 
 paratively very little nitrogen, especially that 
 from herbaceous animals, as almost all the ni- 
 trogen contained in vegetables which is not as- 
 similated in the passage of the food through 
 the stomach passes off through the urinary pas- 
 sages in a liquid form. And as the value of 
 7 
 
66 ORIGIN AND 
 
 manure depends almost as much on the form 
 in which it is presented to plants, as on the ma- 
 nure itself, it is desirable to notice that nitrogen 
 when combined in this, the liquid state, has lost 
 almost all its tendency to assume its gaseous 
 form, and that it exists in urine in the state of 
 carbonate urate and phosphate of ammonia, in 
 those forms in which it is most easily absorbed 
 and assimilated by plants. 
 
 Another source for the supply of ammonia 
 to the vegetable creation, arises from the gases 
 constantly emitted by volcanoes from their cra- 
 ters, and the fissures in their sides in all parts 
 of the world, and which gases always contain 
 ammonia to a greater or less extent. 
 
 Professor Daubeny supposes this to be one 
 of the principal sources for supplying the in- 
 creased quantity of hydrogen, which a con- 
 stantly increasing number of living animals on 
 the earth's surface must require, and the theory 
 has this peculiar merit, that it obviates the dif- 
 ficulty of supposing the atmosphere to have 
 been charged at any time in excess with this 
 gas, and which excess has been gradually ab- 
 sorbed in the structure of the increased num- 
 ber of living animals, to which civilization has 
 given birth in all parts of the world. It also 
 tends to unite the whole scheme of the creation 
 into one vast whole, and to reconcile our minds 
 to these hitherto mysterious operations of na- 
 ture, by explaining the intimate connexion that 
 exists between volcanoes, and the living orga- 
 nization on the earth's surface. The former of 
 which in their eruptions, and at all times, af- 
 
ASSIMILATION OF NITROGEN. 67 
 
 ford, by the emission of these ammoniacal gases, 
 a constant supply of an ingredient necessary 
 for the continual increase of the animal crea- 
 tion. 
 
 To explain the theory of the causes which 
 generate the ammoniacal gases in the bowels 
 of the earth, would be foreign to the purposes 
 of this w^ork. It is sufficient to notice here, 
 their existence and the benefits they are sup- 
 posed to confer on the living organization of 
 the earth.* 
 
 To this cause also, namely the evolution of 
 ammoniacal jgases in the neighbourhood of vol- 
 canoes, Professor Daubeny attributes the lux- 
 uriance which vegetation possesses in all 
 volcanic regions. It may, however, be remem- 
 bered that this luxuriance has already been 
 attributed to the presence of the alkaline pro- 
 perties, which the disintegration of the volca- 
 nic matters in the soil affords to the plant, (page 
 28.) It is possible however and probable, that 
 both these causes united tend to produce this 
 result, which is especially observable in the 
 neighbourhoods of Mount Etna and Vesuvius. 
 
 The effects produced by carbon and nitro- 
 gen on plants, and collaterally on animals, have 
 now been explained, but there is one circum- 
 stance in the assimilation of these substances 
 by animals in their food, which may not be 
 misplaced to notice here. 
 
 It has been before stated that every part of 
 a plant contains nitrogen as well as carbon, but 
 
 * See Daubeny's work " On active and extinct Volcanoes." 
 
68 ORIGIN AND ASSIMILATION OF NITROGEN. 
 
 as an invariable rule, the seed of all plants con- 
 tains a much larger quantity of nitrogen, than 
 the leaves and stalks, and a lesser quantity of 
 carbon, and inversely, the leaves and stalks 
 contain a much greater quantity of carbon, 
 and a lesser quantity of nitrogen. Now when 
 a horse is fed on grass, his food consists almost 
 entirely of carbon, and the result is, that when 
 he has a sufficient supply he gets fat ; that is, 
 that particles of oily fatty matter are deposited 
 on the muscles under the skin, but as it is well 
 known, a horse in this condition is quite un- 
 equal to any work, and the least exertion re- 
 duces his bulk. But when the same horse 
 under other circumstances is fed on corn, his 
 food consists principally of nitrogen, and al- 
 though he may never under this keep, get as 
 fat as under the other, still the increase he does 
 acquire will be pure muscle, or as it is techni- 
 cally called, sound flesh ; and on this keep he 
 can perform infinitely more work with less 
 fatigue, than on food containing no nitrogen. 
 
 A more comiplete instance could not be ad- 
 duced to show^ that animals as well as plants 
 can only assimilate that food which is pre- 
 sented them: in the first case, carbonaceous 
 matters being the food of the horse, carbon is 
 deposited in the shape of fat; in the latter, 
 when more nitrogen enters into the composi- 
 tion of his food, the deposite of muscle prepon- 
 derates. So it is with wheat. With a manure 
 that only supplies carbonaceous matter, starch 
 is the result. With a manure containing ni- 
 trogen, gluten is formed — both cases being 
 
ON WATER. 69 
 
 completely analogous, and affording unerring 
 proof of one simple and uniform law. 
 
 ON WATER. 
 
 Water is next to be considered, and its im- 
 
 fortance in every sense cannot be overrated, 
 t acts in a triple way : First, by its moisture 
 affording a supply of a necessary article in the 
 economy of plants. Secondly, by its solvent 
 properties, it is one of the means employed by 
 nature for rendering salts and other solid mat- 
 ters in a fit state to be absorbed and assimilated 
 by plants. And lastly, by its decomposition, 
 it furnishes hydrogen to combine with carbon, 
 nitrogen, and the various salts which enter 
 into the composition of vegetable products, and 
 restores its oxygen to the atmosphere, to sup- 
 ply the place of that consumed by man, and 
 all animals in the process of respiration. 
 
 This is a mere outline of the important parts 
 it performs, and therefore it will merit some 
 farther consideration to comprehend its chemi- 
 cal analysis. In its ordinary state, water is 
 never pure; that is, it always contains carbonic 
 acid gas, the salts of lime, soda, magnesia, pot- 
 ash, and frequently ammonia; all of which are 
 essentially useful to promote vegetation — in- 
 deed, water in its pure state, will not of itself 
 support vegetable life, and its solvent power 
 is, therefore, one of its most important attri- 
 butes. 
 
 In its chemical analysis, water yields oxy- 
 7* 
 
to ON HYDROGEN. 
 
 gen and hydrogen in the proportion of nearly 
 89 parts of the former to 1 1 parts of the latter. 
 It may be produced at any time artificially, 
 by a mixture of these gases in their relative 
 proportions, and then passing an electric shock 
 through the mixture. This effects the chemi- 
 cal union of the two gases, and the product is 
 water of the utmost purity, and of the exact 
 weight of the two gases employed. 
 
 Part of. the water when absorbed by plants, 
 remains as a fluid in the substance of the 
 plant, and is evaporated from the leaves after 
 having deposited the salts it may contain, and 
 yielded up all the carbonic acid gas it may 
 have held in solution for the nutriment of the 
 plant. Another part undergoes chemical de- 
 composition, and is resolved into' its elements 
 oxygen and hydrogen ; the former passes off 
 through the leaves, and tends to supply the 
 place previously occupied by the carbon ab- 
 sorbed by the plant; the latter, hydrogen, en- 
 ters into composition with the carbon, and 
 tends to form the resinous and oleaginous mat- 
 ter of the plant, and under other circumstances 
 combines with nitrogen to form ammonia, — 
 after carbon the nutriment the most necessary 
 to the growth and development of vegetable 
 life. 
 
 The most positive proof exists, that plants 
 do decompose the water absorbed by their 
 roots, and assimilate the hydrogen, from the 
 fact that caoutchouc or Indian-rubber, the vo- 
 latile oils, wax, and other matters, the products 
 of vegetalDles, consist almost wholly of hydro- 
 
ON OXYGEN. 7L 
 
 gen without any oxygen, and that there is no 
 other source from which this supply can be 
 obtained. 
 
 The hydrogen, therefore, necessary for the 
 formation of an organic compound, is supplied 
 to the plant by the decomposition of the water 
 absorbed by the roots. The process of assimi- 
 lation in its most simple form, consists in the 
 extraction of hydrogen from water, and carbon 
 from carbonic acid gas. The oxygen resulting 
 in both cases from such decomposition, being 
 either assimilated in the production of the acid 
 properties common to some plants, or rejected 
 to supply the necessary waste, or to re-form 
 water with the hydrogen emitted by- plants in 
 the process of decay. 
 
 Oxygen, the other constituent of water, and 
 the vivifying principle of the atmosphere sur- 
 rounding the globe, is one of the most active 
 agents in nature-— it is the supporter of com- 
 bustion, the source of life to all living animals, 
 and acting as the prime agent in decomposing 
 other matters, and rendering it fit for other 
 processes, it enters into compounds with almost 
 every substance known, forming a class of sub- 
 stances called oxides, which from the variety 
 of forms under which they are found, and the 
 important new combinations they again enter 
 into with other substances, may fairly be reck- 
 oned as the most prolific in nature. 
 
 The part this gas performs in the vegetable 
 economy is certainly subordinate to that per- 
 formed by carbon, nitrogen, and hydrogen ; its 
 
72 ASSIMILATION OF 
 
 effects indeed seem rather to be of a negative 
 quality than otherwise, resulting only in a de- 
 ficiency of power, in the various classes of 
 plants, to assimilate the carbon and exhale the 
 oxygen set free by such assimilation ; but in 
 the effects it produces in rendering other mat- 
 ter in a fit state to become or afford the pabulum 
 to plants, it is equally important with the gases 
 before named. 
 
 All the oxygen gas set free in plants by the 
 assimilation of the hydrogen and carbon, in the 
 manner before noticed, appears under favoura- 
 ble circumstances, to be given off in its pure 
 state, but when such circumstances are not 
 favourable, when indeed the plant may be con- 
 sidered to be in an unhealthy state, from the 
 absence of a sufficient quantity of light to al- 
 low the assimilation of carbon and the decom- 
 position of the water, the oxygen then remains 
 in the plant, and enters into- combination with 
 the salts and other substances it may find 
 there, and gives its peculiar character, that of 
 acidity, to the products of the plant. 
 
 A familiar proof of the effects of oxygen 
 under such circumstances, is the sour acid 
 taste and watery flavour which fruits possess 
 when clouds and rain, during a cold wet sum- 
 mer, intercept the sun's rays and prevent the 
 influence of light on the fruits. 
 
 In this case the water absorbed by the root 
 of the plant exists in its watery state and gives 
 the vapid flavour, whilst the carbon imper- 
 fectly assimilated and the oxygen thus set free, 
 
OXYGEN. 73 
 
 not being exhaled, remains to give the acid 
 taste fruits, under such circumstances invaria- 
 bly possess. 
 
 That such is the result oT the absence of light 
 and heat will be obvious, if it is considered of 
 what the 'analysis of sugar consists, viz. car- 
 bon 43 parts and water 67 parts; thus, if 
 plants, from the absence of that cause which 
 enables them to assimilate their carbon and 
 dispose of their oxygen, are unable to do so, 
 the results must be as is found they are, that 
 under such circumstances the acid taste must 
 predominate over the sweet; and in corrobo- 
 ration of this view it may be noticed that the 
 sugar cane, the plant of all others which yields 
 the greatest amount of carbon, can only be pro- 
 fitably cultivated in the tropics, where a burn- 
 ing sun and unclouded sky enable it to assimi- 
 late a sufficient quantity of ^carbon to produce 
 its due supply of sugar. 
 
 That the cultivation of the beet root in 
 France is no argument against this view of the 
 subject, can be satisfactorily proved from the 
 circumstance that the moment the protective 
 duties which long existed in France for the 
 protection of the home manufacture were 
 abolished, that moment the manufacture from 
 beet root ceased, thus proving that a given 
 quantity of labour in Europe could not pro- 
 duce the same quantity of sugar as in the 
 tropics, simply because the climate is not 
 sufficiently clear to facilitate the assimilating 
 of a sufficient quantity of carbon. 
 
 There are several classes of plants which 
 
74 ASSIMILATION OF 
 
 assimilate oxygen^ or rather oxygen enters 
 into combination with the salts they contain, 
 and gives them their acid taste ; such plants 
 are the common sorl^el and the vine, the one 
 yielding oxalic, the other tartaric acid ; but in 
 these combinations it must be distinctly un- 
 derstood, that although the acid seems to be 
 and is a necessary consequence of the absence 
 of light, and thereby a constituent of the plant, 
 still that it never exists of itself, but always in 
 connexion with some salt termed its base — 
 and it is desirable farther to notice that 
 whether that base be soda, potash, magnesia 
 or lime, that provided a base exists (which 
 ^hereafter will be noticed as a necessary con- 
 stituent of the vegetable economy) the oxygen 
 will unite with it to form its peculiar acid. 
 
 From this it may be inferred, that the pre- 
 sence of the base is always necessary for the 
 assimilation of the oxygen or acidifying 
 principle, that without such base no oxygen 
 could be assimilated ; but the base may and 
 constantly does exist, where the plant is fully 
 developed without any such assimilation of 
 oxygen. 
 
 That these bases are the causes of the 
 acidity of plants, may be demonstrated from 
 the fact that the acid is always in proportion 
 to its base, a definite quantity of the one com- 
 bining with a definite proportion of the other ; 
 thus, in the grape for example, the quantity 
 of potash contained in its juice is less when it 
 is ripe than when unripe, so likewise the pota- 
 toe plant contains more potash before blossom- 
 
OXYGEN. 75 
 
 ing than after.* The leaves are the part of 
 the plant which contains the greatest quantity 
 of these bases, and hence their absorption of a 
 larger quantity of the gases forming the va- 
 rious salts met with in the vegetable tribe. 
 
 There are many other peculiar acids which 
 are found by analysis to exist in the substance 
 of plants, but as they do not exist ^er se^ in a 
 gaseous or other state, but as a general rule 
 are composed of various proportions of oxygen 
 combined with other gases and united with 
 some base, it is not intended to pursue this 
 branch of the subject farther, as the considera- 
 tion of each, peculiar acid would lead us far- 
 beyond the limits proposed. It is simply 
 necessary to repeat that in almost every case* 
 oxygen forms the acidifying principle. 
 
 * Liebig. 
 
CHAPTER V. 
 
 ON THE SOLID EARTHY SUBSTANCES WHICH ARE 
 ASSIMILATED BY PLANTS. 
 
 The solid earthy matters, such as potash, 
 soda, magnesia, lime, silex, phosphorus, all of 
 which perform important oflSces in the growth 
 jof plants, are next to be considered ; and here 
 it must be observed that these substances differ 
 materially from the gases already discussed. 
 In this latter case it has been seen how the 
 gaseous bodies exist as solids, as liquids, and 
 as gases, in each state performing important 
 functions in the vegetable economy; but, in 
 noticing the earthy salts, it must be distinctly 
 understood that they exist only as solids, and 
 that the soil exclusively contains them. Hence, 
 the only way in which they can be absorbed 
 into the plant is, by the spongelets of the roots 
 when in a state of solutioti.* 
 
 The analysis of a few vegetable structures is 
 
 * This iact as a general rule is perfectly true ; but the at- 
 inoq>here over the sea contains a very small portion of the 
 saline matter of the ocean in sc^ution, which may serve to ac- 
 count for the circumstance that all (dants growing on or near 
 the sea-shore, assimilate soda in their structure. 
 
ANALYSIS OF PLANTS. TT 
 
 now given, that the importance of these earthy 
 matters in the vegetable economy may be fully 
 appreciated. 
 
 100 parts of the ashes of wheat straw yield 
 
 Saline matter, principally carbonate and sul- 
 phate of potash .... 22$ parts 
 Phosphate of lime .... 6| parts 
 Silicate of potash or flint . . . 611 parts 
 Carbonate of lime, metallic oxide and loss . 94 parts 
 
 100 
 
 4i 100 parts of the bran of wheat yield 44 parts 
 of^he phosphates of lime and magnesia, 100 
 parts of barley yield 32 parts of these phos- 
 phates. — (.Johnson.) 
 
 100 parts of the ashes of the grain of wheat 
 contain 76 parts of these phosphates. — {De 
 Saussure,) 
 
 The ashes of beech-wood yield 20 per cent, 
 of their weight of the phosphates of lime and 
 magnesia. — {Berthier. ) 
 
 Nearly one-half the weight of the ashes of 
 oak leaves consists of soda and potash. — {De 
 Saussure. ) 
 
 100 parts of the fir grown in Norway yielded 
 on analysis, 
 
 Potash 
 
 , 
 
 U 
 
 Soda 
 
 . 
 
 20 
 
 Lime 
 
 , 
 
 12 
 
 Magnesia . 
 
 . 
 
 4=50 parts or one half 
 
 The above analysis of vegetable substances, 
 must demonstrate that these earthy salt« are 
 8 
 
78 ANALYSIS OF PLANTS. 
 
 essential to the development of plants in a va- 
 riety of ways. 
 
 First. As one or more of these salts is a com- 
 ponent part of every plant that exists, it may 
 be thence fairly presumed that its presence is 
 absolutely necessary. 
 
 Again. Plants growing in a situation where 
 these substances are not to be met with, are 
 diminutive in size, their organs are not fully 
 developed, and in many instances they perish 
 altogether after having attained a certain 
 growth; and lastly, soda, lime, magnesia, and 
 phosphorus, enter largely into the structure of 
 the bones and teeth ; and as all animals are de- 
 pendant on vegetation for their support, either 
 directly or indirectly, and as no other means 
 naturally exist for supplying these necessaries 
 to the animal frame, it is not, perhaps, saying 
 too much, when it is humbly presumed that 
 this property of plants, may have been intended 
 as the means of supplying these substances to 
 the animal frame. And if this view of the case 
 is correct, it cannot fail to exalt our ideas of 
 the harmony that exists in all parts of the cre- 
 ation, of the admirable adaptation of the means 
 to obtain a given end, in thus making the ne- 
 cessities of one part of the creation serve as a 
 benefit to the other. 
 
 It is here also worthy of remark, that plants 
 generally possess the power of assimilating, 
 either of the principal alkalis, soda, or potash 
 indiscriminately, and either appears equally 
 adapted to the nutrition of the plant ; for in- 
 stance, wheat manured with either the nitrates 
 
ON POTASH. 79 
 
 of soda or potash, appears almost equally be- 
 nefited ; and this circumstance also shows a 
 power of adaptation, which, in its results, is 
 most beneficial. 
 
 ON POTASH. 
 
 Potash, the first in order of the salts exist- 
 ing in the soil, exists abundantly as a natural 
 product. It enters into a combination with al- 
 most all the acids and gases, forming a variety 
 of compounds differing materially from each 
 other, but it is never met with in its pure state. 
 In its natural state it exists most abundantly 
 as a nitrate of potash ; that is, potash combined 
 with nitrogen and oxygen, and in this state it 
 is found in almost every region of the globe ; 
 being, however, present in greater abundance 
 as we approach the tropics. It is found in two 
 states, the one in a perfectly crystallized state 
 in the fissures of limestone rocks. Sec. and the 
 other as a salt in the vegetable soil of the earth. 
 Calcareous strata, containing this crystallized 
 nitrate of potash are found in France, Spain. 
 Germany, South A merica, and the East Indies ; 
 and it is in the soil of the latter country espe- 
 ciall}^ from that contiguous to, and existing in 
 the valleys of the great rivers, that our princi- 
 pal supply is derived. 
 
 In its native crystallized state, it is formed 
 by an efflorescence of the salt itself from the 
 rock containing it, and in every instance where 
 the rock is highly charged with this salt a 
 
80 EXISTENCE OF POTASH. 
 
 fresh efflorescence occurs every day. At a 
 celebrated nitre cave, as it is termed, near Na- 
 ples, the efflorescence formed a deposite of one 
 inch in thickness in the course of a few days, 
 and this, too, in constant succession the one de- 
 posite after the other. 
 
 A familiar exemplification of this efflore- 
 scence takes place when Roman cement is 
 used ; the delicate needle shaped crystals 
 which appear on its surface a few days after it 
 has been applied as an external coating prove, 
 that the stone from which this cement is prepared 
 must contain potash, which thus effloresces, 
 and exemplifies the way in which the natural 
 deposites of this salt are produced. 
 
 Spain of all the countries in Europe is said 
 to contain the greatest quantity of nitre in the 
 vegetable soil. Nearly one-third of the uncul- 
 tivated lands in the southern and eastern pro- 
 vinces yielding a rich supply of it when treated 
 in the following manner. During the winter 
 and spring, the land is ploughed two or three 
 times to the depth of two or three inches. It 
 is then allowed to lie fallow until the middle of 
 September when it is lixiviated or washed with 
 water. The liquor is then evaporated down in 
 the usual manner, and deposites a quantity of 
 nitre, mixed however with from thirty to forty 
 per cent, of common salt. 
 
 In Hungary there are several springs and 
 wells so impregnated with this salt as to be 
 quite unfit for drinking, and indeed in almost 
 every soil in every country it exists to a greater 
 or less extent. 
 
PRODUCED ARTIFICIALLY. 81 
 
 England derives her supply of nitre exclu- 
 sively from her East Indian possessions. Hol- 
 land also does the same, and has done so for 
 ages past; but the other Continental States, 
 having no colonial povssessions, being driven to 
 their own resources to produce this article, 
 have discovered a variety of means of pro- 
 ducing it. In the course of these researches 
 it was found that the superficial soil of farm 
 yards, cattle stalls, cellars, privies, and other 
 places long exposed to the vapour of putrefy- 
 ing animal matter, afforded a supply of this ar- 
 ticle, and farther that the supply was much 
 increased when these soils were mixed with 
 wood ashes. In consequence of these disco- 
 veries various oppressive laws were created in 
 France and elsewhere, giving the crown a 
 right and possession to these nitrous soils 
 wherever they might be found, and companies 
 were formed and charters granted for the sup- 
 ply of this necessary article to the government 
 magazines, but as a necesvsary consequence the 
 land became impoverished from the abstraction 
 of one of its best manures, and the vexations 
 and annoyances to the parties subject to these 
 extortions became so vehement, that a com- 
 mission was appointed by 'I'urgot, the then 
 Minister in France, of which Lavoisier was 
 the head, having for its object to discover the 
 best means to obtain a supply of tliis article. 
 The following is believed to have been the 
 manner in which this important article was 
 produced, or at all events these means may 
 readilv be adopted for forming it. 
 
 8-^ 
 
82 FORMATION OF POTASH. 
 
 The nitre beds in France are composed of 
 nitrous earth taken from farm-yards, stables, 
 privies, &c,, of street sweepings, mild calca- 
 reous earth (chalky soil) or old mortar, plaster, 
 or even of the sweepings of roads paved with 
 limestone, of animal matter, such as night 
 soil, blood, refuse from the skinner's or tan- 
 ner's yards, offal, &c., and of vegetable matter, 
 such as straw, stable litter, saw-dust, spent 
 tanner's bark, leaves, &c., these are all mixed 
 together in somewhat casual proportions, care 
 being taken that a sufficient quantity of calca'- 
 reous matter is present, the heap is then made 
 up into a long bed, protected from the weather 
 by a suitable roof, and is then duly moistened 
 with putrid water or urine. In this way a 
 large'quantity of nitrate is every year produced 
 by lixiviation, but great part of it is now in 
 the state of nitrate of lime, and it requires the 
 addition of a quantity of wood ashes to supply 
 the necessary potash, and convert the result 
 into a pure nitrate of potash, or the wood ashes 
 might be added at the time of forming the 
 bed, using only a small proportion of the cal- 
 careous earth, and this would at once combine 
 and produce in the soil the desired nitrate of 
 potash. 
 
 ^ . The proportion of nitre afforded by these 
 beds is about 12 ozs. for every 100 lbs. of 
 material employed, but the proportion varies 
 both above and below this quantity, accord- 
 ing to the value of the materials employed to 
 form it, and the care subsequently taken in 
 managing it. 
 
NITRATE OF POTASH 83 
 
 There are many other modifications of this 
 manufacture, some infinitely more scientific 
 in their process, and requiring greater care 
 during the different stages of the manufacture, 
 but the one now quoted appears to combine 
 great simplicity with a certain result, and one 
 moreover which is quite within the reach of 
 all agriculturists, to some extent at least, and 
 its adoption as a source of manure to their 
 farms generally, would be sure to prove a pro- 
 fitable speculation, and if this result should 
 only be attained in a few instances, where 
 these things are now neglected, the object of 
 this work will be accomplished. 
 
 It may here be desirable to explain why 
 wood ashes are necessary for the successful 
 production of this salt. It has been stated that 
 all animal matter in its decay yields a copious 
 supply of nitrogen to the atmosphere or soil, 
 all of which would readily combine with pot- 
 ash, to form the nitrate of potash, were it pre- 
 sent; but as the supply of nitrogen, is under 
 almost all circumstances infinitely more abun- 
 dant than the potash, the wood ashes are added 
 to afford such supply and to fix the nitrogen 
 which would otherwise be evolved in a gaseous 
 state. 
 
 This is the constant practice in the East 
 Indies; where the excess of nitrogen after 
 having combined with all the potash existing 
 in the soil, forms a new compound with lime, 
 called nitrate of lime, and to correct this, wood 
 ashes, containing carbonate of potash, are 
 added, and this effects a double decomposition. 
 The nitrogen of the lime unites with the pot- 
 
84 POTASH. 
 
 ash, and the carbon of the potash unites with 
 the lime, thus forming carbonate of lime and 
 nitrate of potash. 
 
 In this case it may appear that, although 
 little or no potash might be present, still that 
 all the nitrogen would be absorbed by the lime, 
 and hence it might be inferred, that as far as 
 the agriculturist was concerned that no loss 
 would accrue to him ; but this is a dangerous 
 doctrine, it is not only a necessary condition 
 that a certain substance should be present in a 
 soil to become the nutriment of the plant ; but 
 it is also necessary that it should be present 
 there in that state in which it most readily fur- 
 nishes such nutriment, and in the present case, 
 with the knowledge already possessed, there is 
 no doubt but that the nitrate of potash is a 
 more efficient manure than the nitrate of lime. 
 
 Potash is, as we have previously noticed, 
 never met with in its free state, but always in 
 combination with some acid or gas. Thus it 
 has been explained that the potash contained in 
 wood ashes is a carbonate of potash, whilst 
 that in the soil is a nitrate of potash, and it 
 exists in an impure state, in a variety of com- 
 binations, but the two just specified are those 
 most frequently and commonly met with. In 
 its ultimate analysis nitrate of potash, is an 
 oxide of the metal potassum combined with ni- 
 trogen, and the carbonate of potash is an oxide 
 of the same metal united to carbon. This is 
 not exactly the way in which it would be che- 
 mically expressed, but it is sufficiently clear 
 and distinct for the purpose here required. 
 
 In whatever state it may exist in the soil, its 
 
SODA. 85 
 
 assimilation by the plant is the same, that is, 
 it must be taken up by the roots when in a 
 state of solution, and thus be distributed over 
 the whole plant, when its decomposition will 
 at once take place; in the case of the nitrate of 
 potash, the nitrogen is set free to combine with 
 other matters to form the gluten of the seed, 
 and in the state of carbonate, the carbonic acid 
 gas is assimilated as carbon, giving off the 
 oxygen, and in both cases the potash is set free 
 to form a base for the peculiar acid of the plant, 
 be it malic, oxalic, or any other. 
 
 ON SODA. ) 
 
 The next salt in the solid substances neces- 
 sary for the development of plants is now to be 
 explained, and its presence is so universal, that 
 the remarks we have made respecting potash 
 will equally apply to soda. 
 
 It is found in almost all soils combined 
 with potash, but generally in a lesser propor- 
 tion and as a muriate of soda instead of a 
 nitrate. 
 
 The sea is the great source of this salt, and 
 all marine plants, as well as plants growing 
 on or near the sea coast, assimilate this salt 
 instead of potash. It exists also abundantly 
 combined with chlorine (common salt) in va- 
 rious parts of the globe, and in our own coun- 
 try the native rock salt is a source of a consi- 
 derable commerce, and is the basis of many 
 changes. 
 
86 COMMON SALT. 
 
 Soda like potash is never found in its pure 
 state, but always combined with some acid, 
 indeed it is with difficulty obtained in any 
 other form. 
 
 We purpose here to consider this salt in 
 the three states only in which it exists most 
 abundantly, viz. — ^as common salt, a combi- 
 nation of chlorine and sodium ; common soda, 
 such as is sold in the shops for washing and 
 other purposes; and nitrate of soda: — all of 
 which have an important influence on vegeta- 
 tion. 
 
 In its combinations with other acids this salt 
 is quite unimportant as far as its uses in agri- 
 culture are concerned. 
 
 Common Salt. — The first state of soda that 
 comes under our notice is a compound of chlo- 
 rine gas and sodium, in the proportion of 36 
 atoms of the former to 24 of the latter. It ex- 
 ists abundantly as a native product in many 
 parts of the globe ; but in others it is almost 
 deficient. 
 
 In our own country it forms an immense 
 source of traffic, not only with those places 
 distant from its sources, but also with many 
 European states where it does not so abun- 
 dantly exist. 
 
 There are three sources from which this 
 salt is derived, first as a native rock salt at 
 Northwich in Cheshire, next from the brine 
 spring at Droitwich in Worcestershire, and 
 lastly by evaporating the sea water and thereby 
 obtaining the salt held in solution. 
 
 Some idea may be formed of the immense 
 
COMMON SALT. 87 
 
 consumption of this necessary article by stating 
 that upwards of 140,000 tons of salt are annu- 
 ally exported from Liverpool alone, and that 
 from the salt springs at Droitwich, upwards of 
 16,000 tons more of pure salt are annually pro- 
 duced, to say nothing of the immense quantity 
 manufactured from sea-water in various parts 
 of the kingdom. The first kind, the rock salt, 
 is extensively used for agricultural purposes, 
 principally for the use of sheep and cattle ge- 
 nerally, and there can be no doubt of the utility 
 of this substance for them, if only exhibited 
 by the fondness of sheep, horses, and generally 
 all herbiferous animals for it. The last two 
 kinds, obtained by evaporating the brine to the 
 state of common salt, are those which are ge- 
 nerally used as a manure, and perhaps there is 
 no one article that has been more the subject 
 of discussion than this, and one about which 
 greater unc^jrtainty seems even now, notwith- 
 standing all that has been said, to prevail. It 
 is not our province to add more here on the 
 subject, than to express a decided conviction 
 that its use in many cases would be very bene- 
 ficial ; but greater care is perhaps necessary in 
 its application than in any other of the salts of 
 soda. 
 
 One complaint that is made constantly 
 against the use of this salt is, that it produces 
 absolute sterility if the quantity is at all in 
 excess, and the fear of this result interferes 
 with its use. This effect arises from the 
 caustic nature of the gas with which the soda 
 is combined, viz. the chlorine, and as this body 
 
88 COMMON SALT. 
 
 is not necessary to vegetable life, it acts when 
 in excess as a poison. 
 
 Various suggestions have been made for 
 modifying this effect of the common salt One 
 of the latest writers on the subject is a Mr. 
 Henrj Kemp of Poole, who states that he has 
 discovered a ready and efficacious means of 
 decomposing common salt and neutralizing its 
 caustic property, and he speaks of the success 
 that has attended its use in his own immediate 
 neighbourhood as having been very decided. 
 This is precisely what our previous reasoning 
 would have led us to anticipate, as when decom- 
 posed, the noxious property of the gas is got 
 rid of, and its beneficial property onty retained 
 to act on vegetation. 
 
 Mr. Kemp unfortunately, in his pamphlet, 
 does not say how or in what manner he has 
 succeeded in thus decomposing salt at such 
 a rate of expense as would alTov^ of its use 
 in agriculture. He merely states the fact that 
 he had done so, and speaks of the beneficial 
 results he has attained, but declines describing 
 his process unless he is remunerated for it. 
 Whether he has as yet divulged this secret, 
 or whether there is any probability of his doing 
 so is not known, as, since the publication 
 of his pamphlet, which deservedly attracted 
 attention at the time (1832,) we have heard 
 nothing about it. 
 
 Mr. Johnson, in his valuable work on 
 manures, gives all the information that is 
 known, and a great variety of experiments 
 that have been made with common salt, and to 
 
COMMON SODA. 89^ 
 
 that work the reader is referred for farther in- 
 formation as to the success that has attended 
 its use, — the quantity applied, — its mode of 
 application, &lc. Here it is only our province 
 to explain the chemical effects produced by 
 this substance on vegetation. 
 
 Common Soda is an impure sub-carbonate of 
 soda, that is, soda united with carbonic acid 
 gas. In this state it is sometimes found in na- 
 ture, but the principal source of supply arises 
 from lixiviating the ashes of burnt sea- weed, 
 such as kelp and barilla, &c. Extensive ma- 
 nufactories exist for the production of this ne- 
 cessary article in Scotland and various other 
 parts of the kingdom, and it is also produced 
 as a refuse matter from other salts of soda, in 
 the alkaline manufactories throughout the 
 country. 
 
 It is to the presence of this salt that the fer- 
 tilizing properties of the ashes of sea- weed may 
 be attributed, and its addition to the compost 
 heaps spoken of in page 82, would furnish the 
 alkali necessary for fixing the nitrogen, and 
 thus afford a more certain result than can be 
 obtained from the use of wood ashes. The 
 combination however in this ca§e would be a 
 nitrate of soda instead of nitrate of potash. 
 
 The use of this salt as a manure would be 
 valuable to any soil deficient in alkaline matters, 
 to w^hich by its solution in the first rain it 
 would afford an ample supply, whilst the car- 
 bonic acid gas, that would at the same time be 
 9 
 
90 NITRATE OF SODA. 
 
 set free, would furnish a necessary ingredient 
 in the economy of plants. 
 
 Its use however as a manure is very limited, 
 the results it is presumed not being adequate 
 to its price (about £^I1. per ton.) It might 
 however in certain cases be found a ready 
 means of supplying an alkali to the soil, and we 
 are inclined to believe that it* has not in all 
 cases received that attention from agriculturists 
 which its merits would warrant. 
 
 JVitrate of Soda. — This salt, which of late 
 has attracted so much attention amongst agri- 
 culturists, is a native production of Peru. It 
 is there met with in large quantities about four- 
 teen leagues from the port of Iquicque, where 
 it forms a stratum from two to three feet thick, 
 lying close beneath the surface, and following 
 the margin of a grand basin or plain elevated 
 3300 feet above the level of the Pacific Ocean, 
 but which nevertheless appears at one time to 
 have been a lake or inland sea. 
 
 When first introduced into this country, some 
 ten or twelve years since, a few tons only were 
 imported, and then not with any view to its use 
 for agricultural purposes, but merely as a sub- 
 stitute for the nitrate of potash, in making nitric 
 acid, &c., and even Dr. Henry in his Elements 
 of Chemistry, (published in 1829,) when speak- 
 ing of this article says, " its only use is as a 
 substitute for gunpowder in making fire- 
 works." So little can even the first abilities 
 foresee the uses to which any substance may 
 be subsequently employed. 
 
NITRATE OF SODA. 91 
 
 The few tons thus imported laid on hand for 
 some time, no profitable use having been dis- 
 covered for the article, when it was suggested 
 that it might be profitably employed for agri- 
 cultural purposes. A trial was made, and the 
 immense benefits resulting from its use became 
 at once apparent, and from that time to the pre- 
 sent a continually increasing demand for it has 
 existed, which has raised the annual importation 
 into the port of Liverpool alone, to upwards of 
 55,000 bags, and at the present time there seems 
 to be no limit but its price to its universal use. 
 
 In its analysis 100 parts yield, 
 
 Nitric Acid, 58 parts. 
 Soda, 42 parts. 
 
 and 100 parts of nitric acid are again resolva- 
 ble into 
 
 Nitrogen, 26 parts. 
 
 Oxygen 74 parts. 
 
 So that each 100 parts of the nitrate of soda, 
 contains about 15 parts of pure nitrogen. 
 
 It would be foreign to our purpose to note 
 here the various results that have followed the 
 use of this manure, and even were it not, it 
 would bo a work of supererogation, as it is 
 now so established and so universally used, 
 that each parish almost throughout England 
 can furnish some evidence of the benefits de- 
 rived from its use. 
 
 Our object here will be to prove that grasses 
 
92 NITRATE OF SODA. 
 
 and corn of all kinds, and wheat especially, 
 are benefited to a great extent by the nitrate 
 of soda, and that its use materially increases 
 the weight of the wheat itself, and by a neces- 
 sary consequence its nutritive properties. 
 
 It has been demonstrated (page 58,) that the 
 gluten of wheat is that part of the grain which 
 contains the greatest nourishment, and that 
 which gives to wheat its great specific gravity. 
 Now if we can establish the fact, that the use 
 of this manure not only increases the quantity, 
 but at the same time improves the quality of 
 the corn; we think we shall have said all that 
 need be necessary to urge its continued use, 
 and if millers and bakers especially, the parties 
 to whom, in a commercial point of view, these 
 attributes are indispensable, were fully cogni- 
 zant of the individual benefit they, as well as 
 the public, would derive from the application 
 of this substance to the corn, they would pur- 
 chase no other wheat, but such as had been so 
 manured. 
 
 To prove this position we must go into some 
 detail, and illustrate this subject with the re- 
 sults of some experiments introduced by Pro- 
 fessor Daubeny in his third lecture delivered 
 at Oxford. 
 
 In an analysis of 100 parts of two different 
 specimens of wheat, which were grown in the 
 same field, one of which had been dressed with 
 the nitrate of soda, and the other not, the re- 
 sult was — 
 
NITRATE OF SODA. 93 
 
 
 Wheat on which 
 
 
 Wheat on which no 
 
 
 nitrate was used, 
 
 
 nitrate was used, 
 
 
 gave 
 
 
 gave 
 
 Bran . 
 
 . 25 
 
 — 
 
 24 
 
 Gluten 
 
 23i 
 
 J— 
 
 19 
 
 Starch 
 
 . . 49.1 
 
 — 
 
 55i 
 
 Albumen . 
 
 . . u 
 
 — 
 
 1 
 
 Extract, loss and water . 1 
 
 — 
 
 1 
 
 100 100 
 
 Thus it is seen that the wheat so nitrated, 
 contains 4| per cent, more gluten, and | per 
 cent, more albumen than the wheat not so 
 nitrated ; and, as it has been stated, that gluten 
 is the substance to which flour owes its nutri- 
 tious qualities — this alone would prove our po« 
 sition. But if we carry our investigation far- 
 ther, and see its results as to the real produce 
 of bread, we shall be more fully convinced 
 than ever of the utility of this manure : and, 
 here again, we rescrt to experiments made by 
 the same distinguished professor for an elu- 
 cidation of this fact. 
 
 Three pounds and a half of flour, made from 
 wheat dressed with nitrates, produces 4 lbs. 
 14 ozs. of bread ; whilst three and a half pounds 
 of flour, made from wheat where no nitrate 
 was used, yielded only 4 lbs. 4 oz.s. of bread : 
 thus leaving ten ounces of bread in favour of 
 the wheat so nitrated.* 
 
 ♦ The flour from which Professor Daubeny's experiments 
 were made, was obtained from wheat manured with the ni- 
 trate of potasli. But still as wheat manured with the nitrate 
 
 0^ 
 
94 NITRATE OF SODA. 
 
 No other argument can be necessary to con- 
 vince even the most skeptical of the value of 
 this article as a manure. Its benefits to the 
 individual, as well as to the nation at large, are 
 incalculable; and it only ought to serve as a 
 stimulus to all parties to exert their influence 
 in extending its general use. 
 
 The action of soda and potash on vegetables, 
 and the way in which they act on vegetable 
 life are so similar, that a description of the one 
 will suffice for both. It is intended, therefore, 
 to describe the action of soda only. 
 
 It has been stated in the analysis of various 
 plants, that both these salts exist in almost all 
 plants, generally as carbonates; but potash fre- 
 quently combines with other acids, and is then 
 found in various states. Neither ever exist in 
 the structure of plants as nitrates; this variety 
 being generated only by the process of decom- 
 position of vegetable matter in the soil. 
 
 When the ashes of burnt vegetables, or de- 
 caying vegetable matters in any state, are scat- 
 tered over a field as manure, the salts of soda 
 or potash they may contain are dissolved by 
 the first rain, and carried into the soil, and then 
 are absorbed by the spongelets of the roots of 
 the plants, and here the first process in their 
 assimilation commences. If the salt is present 
 as a carbonate, it is decomposed; the soda 
 being assimilated by the plant in connexion 
 
 of soda is equally rich, as a general rule, in gluten, this cir- 
 cumstance does not at all affect the conclusion we have ar- 
 rived at. 
 
NITRATE OF SODA. 95 
 
 with the peculiar acid each plant contains, and 
 the carbon thus set free, performs the functions 
 attributed to it in a preceding chapter. 
 
 But if the soda is applied in the state of a 
 nitrate, as is now generally the case, especially 
 as a top dressing for white crop, its action is 
 somewhat different. 
 
 In this state the salt, after having been dis- 
 solved and absorbed by the roots, is decom- 
 posed, but in this latter case, nitrogen is assi- 
 milated to form the gluten in the seed, and to 
 enter into the other parts of the plant. 
 
 It is a popular opinion that these salts act on 
 the various soils as stimulants, and that al- 
 though they may increase the vegetation for a 
 season, still that their use is injurious, as they 
 exhaust the soil in the same degree in which 
 the crops are improved. A greater fallacy 
 than this it is scarcely possible to conceive, and 
 even had we not the experience of facts to fall 
 back on, it could be satisfactorily proved that 
 the action of soda and potash, and especially 
 of the nitrates of these salts, are of themselves 
 the cause of the increased luxuriance, and that 
 the soil is, and must be benefited by their ap- 
 plication. Thus, when the nitrate of soda is 
 applied as a top dressing, it is absorbed and 
 decomposed, as already seen ; and, of itself is 
 the cause of the increased weight of the crop 
 and the luxuriant vegetation. It may possibly, 
 and does by giving increased vigour to every 
 part. of the plant, enable it thereby to absorb 
 more nutriment from the air, but it has been 
 already, and it is hoped, sufficiently explained, 
 
96 NITRATE OF SODA. 
 
 that plants after a certain stage, derive their 
 principal nutriment from the atmosphere, and 
 not from the soil; and the increased action 
 that is given to plants from the supply of ni- 
 trogen and soda, enables them to assimilate 
 more carbon from this source. 
 
 A farther proof that the application of -ni- 
 trate of soda has a contrary effect, is known 
 from the circumstance, that crops growing on 
 land that had been dressed during the pre- 
 ceding year with this manure, have during 
 the second season showed the beneficial result 
 of the application, in increased luxuriance, 
 and by their rank deep colour ; a circumstance 
 entirely to be attributed to a portion of the 
 manure still remaining in the soil. Another 
 circumstance corroborative of the truth of these 
 opinions may be collected by reflecting on the 
 routine that is too frequently observable on 
 farms, where a judicious system of agriculture 
 is overlooked ; for instance, many crops are an- 
 nually removed from a certain pasture, and no 
 manure applied until the land becomes entirely 
 exhausted, and w^hen in this state, the applica- 
 tion of the nitrate of soda or potash, at once 
 restores abundance and a rank vegetation. In 
 such instances as these, it cannot force the soil, 
 because on all hands it must be admitted that the 
 land was entirely exhausted; any increase, there- 
 fore, must be entirely attributable to the efforts 
 produced by the presence of these salts. The 
 same remarks will apply to other manures, 
 such as chalk, lime, &c. and will be mentioned 
 under their respective h^ads. 
 
NITRATE OF SODA. 97 
 
 It is only necessary farther to remark, that 
 every crop removed from a soil contains these 
 salts, and unless they are again restored to 
 such soil in the state of manure, or as a pure 
 nitrate, the land must become impoverished 
 and eventually barren. 
 
 In the few cases where the nitrate has failed 
 to produce the effect anticipated, it may pos- 
 sibly be attributed to the absence of the phos- 
 phates of lime and magnesia, and the silicate 
 of potash, all of which are essential to the 
 ffrowth of a white crop, and without which, 
 howsoever abundant the nitrate may be, no 
 crop could be produced. 
 
 It may be, but of this further experience is 
 necessary, that the application of these salts, the 
 nitrates of soda and potash, stimulates peren- 
 nial plants to such an excess, that they are un- 
 able for a time after the action of the salt is 
 over, to compete with similar plants not ex- 
 posed to its action ; but this requires much more 
 observation to confirm the fact, and it does not 
 in any way apply to its use on those crops 
 where it is not only most needed, but at the 
 same time most beneficial. It is only men- 
 tioned here to explain how it is, that in one or 
 two cases where the nitrate of soda was applied 
 during the last spring (1841) to old pastures, 
 and where it produced the most marked and 
 decided effect, that, after the grass was cut and 
 the produce harvested, the after grass was a 
 long time before it came away, and that the 
 grass not manured with this soda then appeared 
 the most luxuriant. This effect however was 
 
98 PHOSPHORUS. 
 
 only for a time, but it serves to convince us that 
 the stimulus is to the plant and not to the soil. 
 
 ON PHOSPHORUS. 
 
 This elementary matter is never found in its 
 pure state. Combined with oxygen gas, it 
 forms phosphoric acid, and this again united 
 with such bases as lime, soda, magnesia, &c., 
 forms the salts termed phosphates, which are 
 met with in animal, as well as in vegetable 
 products. 
 
 Phosphate of lime is, as will hereafter be no- 
 ticed , the principal i ngredient of bones, of which 
 it forms the hard part. A native phosphate of 
 lime occurs abundantly in Spain, under the 
 name of Apatite, and other native combinations 
 of this acid occasionally are met with. 
 
 Phosphorus is an ingredient in urine, and 
 affords another argument in favour of the use 
 of this matter (hereafter to be noticed) as a ma- 
 nure ; as the presence of the phosphates is es- 
 sential to the growth of vegetables, especially 
 of wheat, barley, oats, and rye, in the grain of 
 which it always occurs, and without which no 
 such crop could be perfected, and from this 
 source also the human frame derives its supply 
 of this necessary matter. 
 
 The native phosphates exist in a greater or 
 less degree in all soils, and vegetables there 
 find the supply they require for their growth 
 and development. But as this essential is as 
 easily exhausted by a crop, as the other salts 
 
LIME. 99 
 
 spoken of, it behoves the agriculturist to see 
 that a return of this matter is made to the soil, 
 and in no way can it be either more efficiently 
 or more economically restored, than by the use 
 of urine and animal excrements. 
 
 The specific action of the phosphates of lime 
 and magnesia, the two combinations in which 
 it is most frequently met with will be described 
 under their respective heads, any notice of 
 them here, therefore, would be superfluous. 
 It is simply necessary to note that the phos- 
 phates contained in the urine of all carnivorous 
 animals are the excess over and above that re- 
 quired to supply the waste of the body, and 
 which is thus thrown oflf as refuse matter. 
 
 ON LIME. 
 
 Lime exists abundantly, combined with va^ 
 rious acids, in all parts of the globe, and there 
 are few districts in which this essential sub- 
 stance is not abundant. Indeed so universally 
 diffused is this salt, that every plant that has 
 yet been analyzed, with only one exception, 
 contains a portion of lime in some state or 
 other, which it must have derived from the 
 soil in which it grew. Wheat in flower, when 
 ripe, the straw, the bran, all yield lime when 
 analyzed ; so likewise do barley, oats, vetches, 
 the leaves of various trees, the bark, timber, 
 &c. ; indeed this substance is so universally 
 present in all parts of the vegetable structure, 
 that it may be fairly assumed to be an integral 
 
100 CARBONATE OF LIME. 
 
 portion of all, varying however according to 
 the quantity existing in the soil in w^hich the 
 plants are cultivated. 
 
 One of the most obvious purposes it serves, 
 is to give stability and substance, from its 
 earthy nature, to those parts of the plant, 
 which otherwise would not perhaps have 
 sufficient strength to perform the functions 
 allotted to them ; but that it possesses other 
 properties, there is little doubt, as it is found 
 not only in the stalk, but in the leaves, fruit, 
 and indeed in almost all parts of the plant. 
 
 Carbonate of Lime, that is, lime combined 
 with carbonate acid gas, is the state in which 
 the substance most commonly exists ; in this 
 combination it is known to us under the names 
 of marble, chalk, marl, limestone &c., all being 
 lime combined to a greater or less extent with 
 carbonic acid gas. Chalk, we believe, is the 
 substance of this class which is most commonly 
 used as a manure, or in promoting vegetation. 
 We therefore shall confine ourselves to de- 
 scribing its use, and its mode of action, but, 
 with a fev/ slight modifications, the same re- 
 marks will apply to any of these substances. 
 In its ultimate analysis chalk yields, 
 55 parts of lime, and > .^ ^ ^^^ 
 
 45 parts of carbonic acid gas, 5 j f ' 
 
 and some extraneous matter, such as silex, and 
 oxide of iron. 
 
 In this state it is very sparingly soluble in 
 cold water, but if water charged with carbonic 
 acid gas is present (and all water, as we have 
 before seen, (page 69) does contain this gas,) 
 
CARBONATE OF LIME. 101 
 
 its solvent powers are much increased, and in 
 this way it is absorbed by the spongelets of the 
 roots, and assimilated by the plants; and its slow 
 solution by water is one reason why its eftects 
 are so lasting when applied to a soil. Chalk 
 has been and is extensively used as a manure, 
 and even in some cases on calcareous soils 
 themselves with advantage. 
 
 It produces a mechanical as well as a che-* 
 mical action wherever it is applied. Mecha- 
 nically by dividing the soil, and rendering it 
 more light or friable as it is termed, and che- 
 mically by absorbing moisture from the atmo* 
 sphere and giving it out slowly as vegetation 
 subsequently requires it, as well as by its solu- 
 tion affording a necessary ingredient to the 
 development of all plants. 
 
 All these carbonates of lime w^hen burnt lose 
 their carbonic acid gas, and pure lime is left. 
 The heat destroying the affinity, previously 
 existing between them. Lime in this state is 
 most extensively used for agricultural pur- 
 poses, and as it loses nearly 44 per cent, in 
 weight in burning, it may be well worth the 
 consideration of those agriculturists who live 
 at a distance from chalk to know whether in 
 this state it may not be equally beneficial, as 
 the saving in carriage on such a substance, is 
 a material item in the expense. 
 
 The same remarks we have applied to chalk 
 will equally explain how lime acts on vegeta- 
 tion. 
 
 It is soluble to a slight extent in water^ 
 more largely in cold than in hot water, and 
 10 
 
102 SULPHATE OF LIME. 
 
 more so in water charged with or containing 
 carbonic acid, than in other, — it is then ab- 
 sorbed and assimilated by the plant; but it 
 also is supposed to assist materially in decom- 
 posing dry hard vegetable matter, from its great 
 attraction, when in this its caustic state, for 
 the gases combined with other substances, and 
 hence its use on peaty soils. Care should al- 
 ways be taken to procure this article as fresh 
 and as perfectly burnt as possible, and as short 
 a time as possible before it is made use of, as 
 lime when only just taken from the kiln can 
 be said to be pure, for immediately on its re- 
 moval it begins to absorb the carbonic acid gas 
 of the atmosphere, and to resume its original 
 state of a carbonate of lime. 
 
 It has also a great affinity for nitrogen, with 
 which it readily unites to form nitrate of lime, 
 and although in this state it still produces in a 
 moderate degree the effects produced by lime, 
 its effects are not superior to chalk, which ge- 
 nerally can be obtained at a less cost. 
 
 Sulphate of Lime, or Gypsum composed of 
 sulphuric acid and lime, the next in order and 
 in importance of the compounds of lime, oc- 
 curs native in various districts of England, the 
 most abundant quarries or pits being in Derby- 
 shire. It is found also abundantly in the 
 neighbourhood of Paris, from whence its popu- 
 lar name, "plaster of Paris," is derived. 
 
 The beneficial results arising from the use 
 of this manure on grass lands are admitted 
 on all hands, and even in the few instances 
 where no good results have followed its use, it 
 
SULPHATE OF LIME. 103 
 
 has txK) frequently arisen from the presence of 
 this earth in the native soil itself, where con- 
 sequently its application could do no good; 
 and a more urgent argument for the necessity 
 of a knowledge of chemistry to the agricul- 
 turist, than is furnished by this simple fact, 
 which has occurred more than once in the his- 
 tory of this manure, cannot be cited. 
 
 The action of this earth, gypsum, in pro- 
 ducing such luxuriant effects on grasses arises 
 entirely from its power of absorbing the am- 
 monia of the atmosphere (page 60,) which im- 
 portant article by its solution in water and sub- 
 sequent absorption by the spongelets is thus 
 yielded to the plant itself. 
 
 The ammonia existing in rain water is, when- 
 ever it comes in contact with gypsum, at once 
 absorbed, and a new compound is formed called 
 sulphate of ammonia. In this state the am- 
 monia is fixed, that is, it has no volatile pro- 
 perties, and water is the only thing needed to 
 dissolve this new compound for the use of 
 vegetation, and the absence of moisture will fre- 
 quently explain why gypsum produces either 
 a less effect or no difference at all in dry fields 
 or meadows. The lime disengaged by this 
 action is either dissolved with the sulphate of 
 ammonia and absorbed by the roots, or it com- 
 bines with other gases to form carbonate or ni- 
 trate of lime. 
 
 In order to give some idea of the effect to be 
 produced by gypsum, it may be stated* that 
 
 * Liebig. 
 
104 PHOSPHATE OF LIME. 
 
 100 lbs. of gypsum has the power of fixing as 
 much ammonia as 6000 lbs. of horses urine, 
 even assuming that no loss would occur in the 
 absorption by the plants of all the nitrogen of 
 the latter manure. And if again it is admitted, 
 and anlysis proves that it is so, that 100 
 pounds of grass contain one pound of nitrogen, 
 then every pound of nitrogen that is added to 
 a soil, must produce 100 pounds of grass, and 
 this increased produce is effected by little more 
 than four pounds of gypsum. 
 
 The decomposition of gypsum by this pro- 
 cess of absorption of ammonia, goes on very 
 slowly, and this explains why the action of 
 gypsum lasts for so many years. 
 
 The benefits arising from the use of burnt 
 clay and the fertility of ferruginous soils may 
 all be explained on the same principle, the 
 power these matters possess oY fixing the am- 
 monia of the atmosphere, and subsequently by 
 their solution in water, yielding it to the plant ; 
 indeed all soils, to a greater or less extent, pos- 
 sess the power of absorbing gaseous matter. 
 It has been proposed to sprinkle sulphuric 
 acid over calcareous soils to produce gypsum 
 artificially, but the experiment has not, we 
 believe, ever been tried. 
 
 It would be alike foreign to the purpose in- 
 tended in the publication of this treatise, and 
 useless, to cite examples of the beneficial effects 
 which have resulted from the use of this valua- 
 ble agent. All who wish to know every thing 
 that relates to this and other manures will do 
 well to consult Mr, Cuthbert Johnson's work 
 on Fertilizers. 
 
PHOSPHATE OF LIME. 105 
 
 Phosphate of lime, consisting of lime 65 parts, 
 and phosphoric acid 45 parts, enters largely 
 into the structure of turnips, wheat, and many 
 other crops. It occurs in many composite 
 rocks, and it exists in its native state in Corn- 
 wall, in the north of England, and Spain, and 
 is known by the name of Apatite; in the latter 
 country it is abundantly present in Estrema- 
 dura, where it is so common, that the divisions 
 of the fields are said to be formed of it. In this 
 state, however, it has never been used as a ma- 
 nure, we are therefore unable to speak positive- 
 ly as to its value; but reasoning from analogy, 
 from the beneficial effect that this substance 
 produces in the state of bone dust, there can be 
 little doubt but that its use would prove highly 
 advantageous. 
 
 The chief source of this manure in this coun- 
 try arises from the use of bones; the beneficial 
 effects of which are attributed almost entirely 
 to the phosphate of lime they contain. In their 
 analysis, calcined bones yield between fifty and 
 sixty per cent of* this earth, and when it is 
 found that phosphate of lime exists in almost 
 every part of the grass tribe, in the seed, tho 
 bran and the stem, there is every reason to 
 believe that this is the fertilizing property; 
 and added to this, we have the fact before us, 
 that bones, whether used fresh from the slaugh- 
 ter-house, without having been subjected to 
 any calcining process, whether taken from the 
 kitchen after having been either boiled or 
 roasted, or from the manufactory, where every 
 portion of oil or fatty matter is extracted, or 
 from caves, or other existing deposites of bones, 
 
 10* 
 
106 NITRATE OF LIME. 
 
 where they must have laid for centuries, that 
 bones taken from any of these sources, crushed 
 and applied to the land, are equally beneficial 
 in their results. 
 
 Having thus established the presence of this 
 earth in plants, and its importance as a stimu- 
 lus, the next consideration is to explain its mode 
 of action ; and more difficulty exists in doing 
 this satisfactorily, than in any of the previous 
 substances that have been noticed. 
 
 Phosphate of lime is described as an insipid 
 white powder, insoluble in water, but soluble 
 in dilute nitric, muriatic, and acetic acids, but 
 this does not . at all help to solve the question 
 as to how it is to dissolved in the laboratory of 
 nature. . It is supposed either that the salts and 
 gases which (page 70) are constantly present 
 in water, have a sufficient solvent power to 
 enable the plant to take up this substance, or 
 that the electricity which we know is always 
 present, during any change in the state of mat- 
 ter, and consequently always in action during 
 the germination of seeds and the growth of 
 plants, that this agent exerts an influence in 
 some way or other to allow of the solution of 
 this phosphate of lime in water. 
 
 It is admitted at once and frankly that the 
 theory here set forth is liable to many objec- 
 tions, but so is the subject, and we are by no 
 means yet in a position to explain how the so- 
 lution and assimilation of this substance is 
 effected. 
 
 Nitrate of lime, (nitric acid 66 parts, and lime 
 34 parts, ) exists also in a state of nature. There 
 it is formed by the nitrogen of decaying, ani- 
 
MAGNESIA. 107 
 
 mal and vegetable matter uniting itself with 
 the calcareous matter of the soil ; it is also found 
 to exist in the plaster of old buildings, which 
 have been long inhabited, especially it is abun- 
 dant in the plaster and cement of walls and 
 ceilings near privies, where, from the quantity 
 of nitrogen constantly exhaling, a considerable 
 portion is assimilated. 
 
 Of its use as a manure nothing can be said ; 
 it is not known to exist in any state in plants, 
 and the few experiments I myself have insti- 
 tuted with a view to test its effects, have been 
 so unsatisfactory as to leave little hope of its 
 being beneficially employed hereafter. 
 
 ON MAGNESIA. 
 
 Magnesia^ the next earthy matter we have 
 to consider, is a constituent of almost all 
 plants, and exists abundantly in all parts of 
 the world, in various states of combination. 
 We have only to " recognise it here in the state 
 of a phosphate of magnesia, in which com- 
 bination it is found in the grain of all white 
 crops, and of which it forms a considerable 
 part. 
 
 A native phosphate of magnesia is unknown, 
 the magnesia which we find therefore existing 
 as a phosphate in the corn and husks of all 
 grain, must be absorbed in the state of a car- 
 bonate, that is, dissolved in water by means of 
 carbonic acid gas, or it may be taken up in 
 combination with other acids, in which state 
 it is very soluble, and then being assimilated, 
 
108 MAGNESIA. 
 
 decomposition must take place, the carbonic 
 or other gas being liberated or assimilated, 
 and the magnesia united with the phosphoric 
 acid derived from the lime, or from other 
 sources, as has been explained when speaking 
 of phosphorus. 
 
 Magnesia exists also abundantly in lime- 
 stone, and care should be taken by every per- 
 son about to apply a dressing of lime to his land 
 to know whether the stone or chalk from which 
 it may be burnt, contains magnesia or not, as 
 its use combined with lime is very prejudicial 
 to many soils, whilst on others, its use would 
 be equally beneficial. 
 
 Sir Humphrey Davy explains satisfactorily 
 the reasons why the magnesian limestone is to 
 be avoided, or used with great care as a ma- 
 nure. The reasons he gives are, " That the 
 magnesia of the limestone is much sooner de- 
 prived of its carbonic acid than the lime; and, 
 that when applied to land, it rapidly absorbs 
 the gas from the surrounding humus: but if 
 there should not be a sufficient supply of this 
 carbon, the magnesia will then remain in its 
 caustic state, and in this state it acts as a poi- 
 son to many vegetables. '^ 
 
 Mr. Johnson also, in his able work before 
 quoted, has proved that such is the effect of 
 the magnesian limestone, and acting on Sir 
 Humphrey Davy's experiment, he judiciously 
 recommends its use to restore peaty soils, and 
 vice versa^ the use of peat as a remedy to land 
 where the magnesian limestone has been ap- 
 plied. 
 
SILEX. 109 
 
 ON SILEX. 
 
 Silex, or pure flint, is the next constituent of 
 vegetable matter to be explained. 
 
 It may seem to those whose attention has 
 never been called to the structure and consti- 
 tuents of plants, that the presence of this sub- 
 stance is impossible ; but yet the analysis of 
 wheat straw, which yields upwards of 60 per 
 cent., (the remaining 40 parts consisting of car- 
 bonate of lime (chalk,) phosphate of lime, 
 potash, or soda and iron) prove beyond all ques- 
 tion its presence; and the mode which nature 
 in her vast laboratory employs for the assimila- 
 tion of this substance, will, therefore, be our 
 next consideration. 
 
 Silex, in its pure state, is perfectly insoluble 
 in water; but silex combined with potash, is 
 perfectly so : indeed, there is a species of glass 
 manufactured from these ingredients, which 
 dissolves perfectly in boiling water. And as 
 potash and silex equally abound in almost every 
 soil, it only remains for us to endeavour to ex- 
 plain how this substance may be formed in na- 
 ture; but this, however desirable, is with our 
 present knowledge unattainable. 
 
 We know that nature has the means in her 
 immense galvanic power, which is constantly 
 in operation, in the powerful auxiliaries that 
 she has in the summer's sun, the winter's frost, 
 and the daily variations of moisture, to reduce 
 the most obdurate substances to a state fitting 
 them for change. And we must be content, at 
 present, with the knowledge that such a power 
 
1 10 SILEX. 
 
 is present, and that by its means combinations 
 are produced; but the manner of their produc- 
 tion is as yet a mystery. 
 
 It is, however, probable that a silicate of 
 potash is formed by some process in nature, 
 which is either entirely or sparingly soluble in 
 water; and this admitted, the difficulty at once 
 ceases. In this state it is absorbed by the 
 spongelets of the roots, the silex is assimilated 
 in the straw, and the potash exists to enter into 
 compounds with the various other substances 
 present, and to perform the functions elsewhere 
 described. 
 
 Silex is one of the most abundant products 
 in nature; it constitutes a principal ingredient 
 in granite, it composes a large portion of the 
 sand found in beds of rivers, and on the sea 
 shore, and it enters largely into several mine- 
 rals of rarer occurrence, such as rock crystal, 
 quartz, cornelian, &c. 
 
 Its mechanical use in agriculture is very 
 great, as it serves to render heavy soils porous, 
 and open to the transmission of moisture, and 
 with this view it is extensively used ; although 
 this action must not be confounded with the use 
 of the calcareous sand in Cornwall, the western 
 part of Ireland, and other places, where the be- 
 nefit derived arises entirely from the calcareous 
 nature of the sand so employed. 
 
 This then concludes the description of those 
 substances which are assimilated by plants. 
 
 It has been showed, it is hoped satisfactorily, 
 the sources from which these simples are de- 
 rived, their mode of action, and the compounds 
 they enter into, and the analysis of the various 
 
SILEX. Ill 
 
 vegetable products that have been given in 
 treating of this subject, must convince even the 
 most skeptical, how all-important these sub- 
 stances are; and that no plant or vegetable 
 structure can ever exist without the agency of 
 the simples thus imperfectly described. 
 
 Farther experience will probably tend to 
 elucidate much that is now obscure in the pro- 
 cesses nature employs, and each fresh dis- 
 covery that is made not only simplifies the 
 subject, but is a double step in advance; as 
 such discovery not only tends to simplify what 
 is already comprehended, but gives us a firmer 
 footing on v^hich to base our future operations. 
 
CHAPTER VI. 
 
 ON MANURES. 
 
 To render the subject of the preceding chap- 
 ters as complete as possible, it is desirable that 
 the specific action of each individual manure 
 should be perfectly understood. Without a 
 full understanding on this point, it is impossi- 
 ble for the agriculturist to decide with a cer- 
 tainty of success on the manure for a certain 
 crop, or the best management to be adopted, 
 and although a keen habit of observation vt^ill 
 and does go far to supply this deficiency ; still 
 an explanation of the peculiar action of each 
 manure on the soil or crop, cannot but be use- 
 ful, to say the least : and, in the majority of 
 cases, such knowledge will be eminently ser- 
 viceable to determine the time proper for the 
 application of any particular substance, the 
 quantity to be used, and the best manner of 
 applying it. 
 
 Having thus premised, it only remains to 
 say, that all substances, whether liquid or 
 solid, which are applied to the soil to promote 
 the growth and vegetation of plants, will be 
 considered as manure ; and although the sub- 
 joined list is far from containing all the mat- 
 ters thus made use of, still, a sufficient selec- 
 tion is given, from which the effects of others 
 not mentioned may be inferred. 
 
ON MANURES. 113 
 
 It is, therefore, proposed to consider these 
 substances in the following order : — 
 
 Ammonia, 
 
 Guano, 
 
 Ashes — Wood, 
 
 Gypsum, 
 
 Coal, 
 
 Lime, 
 
 •* Peat, 
 
 Liquid Manure, 
 
 Blubber, 
 
 Night soil, 
 
 Bones, 
 
 Clarke's do. 
 
 Chalk, 
 
 Potash, 
 
 Charcoal, 
 
 Salt, 
 
 Dung — Farm-yard, 
 
 Saltpetre, 
 
 ♦* Birds, 
 
 Soda, 
 
 Dogs, 
 
 Soot, 
 
 Fish, 
 
 Urine, 
 
 Fish-oil, 
 
 Urate, 
 
 Gas liquor, 
 
 Woollen rags. 
 
 " lime. 
 
 Irrigation. 
 
 Ammonia. — Already under the head " nitro- 
 gen," (p. 60) this substance has been fully 
 discussed, and the important part it performs 
 in vegetable economy fully described, and 
 to this article therefore we beg to refer the 
 reader. 
 
 The chemical analysis of ammonia yields 
 three volumes of hydrogen and one of nitro- 
 gen, and it is to the presence of this latter sub- 
 stance that the effects produced on vegetables 
 are to be attributed. This combination is one 
 of the most simple compounds of nitrogen that 
 exists, and yet certain conditions are necessary 
 for its union with hydrogen. It is not at all 
 necessary here to detail what these conditions 
 are, it is only necessary to repeat what we have 
 previously stated, that the nitrogen of the atmo- 
 sphere does not in any way combine with hy- 
 drogen to form ammonia; it is only formed 
 11 
 
114 WOOD ASHES. 
 
 when these two gases are liberated in contact, 
 as in the decay of animal and vegetable mat- 
 ter, where it is always present ; the nitrogen 
 being set free by the decomposition of the 
 matter itself, and the hydrogen being evolved 
 from the decomposition of water, which is 
 always and under all circumstances necessary 
 to produce the ultimate decay of matter. 
 
 Its price as an article of commerce will, it is 
 feared, always prevent its use in a manufac- 
 tured state, and indeed, if we only reflect on 
 the immense quantities of this manure which 
 are now wasted, and which might and ought 
 to be saved, we shall be convinced that we 
 never need apply to the manufactured article 
 for a due supply of this important matter. 
 
 Ashes — Wood. — The benefit arising from the 
 use of wood-ashes arises entirely from the pot- 
 ash they contain, which being dissolved by the 
 first rain that falls after they are appUed, dis- 
 solves the salt and carries it into the earth, 
 there to be absorbed and assimilated as pre- 
 viously described. 
 
 Some kinds of wood (and in wood we should 
 include all plants) yield in their lixiviation a 
 much larger quantity of this salt than others, — 
 thus the ashes of dried wormwood contain 30 per 
 cent, of this salt, and are consequently very bene- 
 ficial. The ashes of nettles, and generally the 
 ashes of all plants which flourish on rubbish 
 heaps, the ruins of old buildings, and in hedge 
 rows are rich in these salts, as their luxuriant 
 growth testifies to the abundant presence of the 
 potash in the soil where they exist, and it would 
 amply repay the agriculturist to collect such ve- 
 
COAL ASHES. 116 
 
 getables, merely for the sake of the potash they 
 contain, to help to form the compost heap be- 
 fore mentioned. 
 
 The ashes of beech seem to possess a pecu- 
 liar quality in addition to the salts of potash, 
 viz. phosphates; and it is calculated that 100 
 lbs. of the lixiviated ashes of the beech, would 
 yield as much phosphate as 400 lbs. of fresh 
 human excrement, or enough to supply suffi- 
 cient phosphoric acid for the production of 
 3S20 lbs. of straw, or from 15 to 18,000 lbs. 
 of corn. 
 
 Coal ashes — yield, on analysis, a small por- 
 tion of sulphate of lime (gypsum,) charcoal 
 and lime. The beneficial results arising from 
 the use of these ashes are generally attributed 
 to the sulphate of lime they contain ; but as 
 these results are so much greater, than are 
 produced by an equal proportion of the sul- 
 phate, when applied in its pure state (that of 
 gypsum,) the cause must be sought for in 
 some other ingredient they contain ; and with 
 deference to those who have previously written 
 on this subject, the greater portion of the good 
 effect attending the use of coal ashes, may be 
 attributed to the presence of the charcoal they 
 contain. Elsewhere, the power possessed by 
 charcoal of absorbing other gases, and again 
 yielding them to the soil, will be alluded to, 
 and it is to this power and the presence of car- 
 bon and nitrogen thus absorbed, that the bene- 
 fit is supposed to be due. The lime which 
 exists, independently of the gypsum, may 
 also produce its effect, but the quantity con- 
 tained in coal ashes is too small for it to be 
 
116 ON MANURES. 
 
 the cause of the luxuriant effects which follow 
 their use. Jt is here needless to repeat the 
 effects produced by carbon and nitrogen on 
 vegetation ; the chapter devoted to each, will, 
 it is hoped, fully explain their uses in con- 
 nexion with the growth of plants. 
 
 Peat ashes, owe all their fertilizing property 
 to the presence of 12 per cent, of gypsum, and 
 the remarks made when speaking of that sub- 
 stance, (p. 103) will fully apply here. Rain 
 is absolutely necessary, in all cases where 
 gypsum is applied, to produce the desired 
 effects ; it acts by dissolving the ammonia ab- 
 sorbed by the gypsum, and which is thus con- 
 veyed into the soil, there to be absorbed and 
 assimilated in the manner previously described. 
 
 The analysis of peat ashes yields 12 per 
 cent, of sulphate of lime,— a sufficient quantity 
 to account for the beneficial results which fol- 
 low their use. 
 
 The other products of the analysis consist of 
 40 parts of carbonate of lime. 
 
 6 parts of salts of soda. 
 32 parts of si licious earth. 
 
 3 parts of oxide of iron. 
 
 7 loss. 
 
 Blubber, fish, oils, fat, S^c. — The analysis of 
 these substances yields upwards of 70 per cent, 
 of carbon, on which all their fertilizing pro- 
 perty depends. The first requisite, therefore, 
 is so to mix them, that the carbon may become 
 available when applied to the soil, and not, as 
 in too many cases, so combined as to form 
 either an insoluble compound, or one which is 
 so readily found in nature as to render it quite 
 
BLUBBER. 117 
 
 unnecessary for it to be manufactured in a 
 more expensive way. 
 
 We would recommend, as the best means of 
 preparing these substances for manures, that 
 one or two gallons of either of the above oils 
 should be mixed with five or six bushels of 
 fresh coal ashes or charcoal, or a mixture of 
 both. After laying a few days in this state 
 fermentation would take place, the oil would 
 be decomposed, and the carbon thus set free, 
 would be at once absorbed by the charcoal or 
 ashes, and as soon as ever this had taken place 
 they should at once be used. 
 
 If to this mixture it were possible to add, as 
 there is every reason to hope soon will be the 
 case, some of the apatite or native phosphate of 
 lime, we conceive that such a mixture would 
 answer admirably for turnips ; as it would fur- 
 nish every requisite for the young plants and 
 stimulate their growth, so as to render the ef- 
 fects of the fly, the black caterpillar, and the 
 other enemies of this plant, quite abortive. 
 
 If these substances are mixed with lime, as 
 is or has frequently hitherto been the case, de- 
 composition speedily ensues, and the carbon 
 resulting from such decomposition is at once 
 absorbed by the lime to form carbonate of lime ; 
 a substance which it is not at all necessary thus 
 to manufacture, seeing that it exists already 
 abundantly in nature as chalk and limestone. 
 
 Fish, such as sprats, cockles, muscles, which 
 in various parts of England are extensively 
 used as a manure, are only valuable for the 
 oil they contain, and being applied at once to 
 the soil, the oil that is yielded during decom- 
 
 11 * 
 
118 BONES. 
 
 position is at once absorbed ; but as the quan- 
 tity so applied is very small, the effects of a 
 dressing of these fish seldom lasts beyond a 
 year. 
 
 The price of oils, even the commonest that 
 are to be had and during the cheapest years, 
 (varying from 2s to 2^ 6d per gallon) is such 
 as to be a serious obstacle in the way of their 
 use as a manure, the more so as other sub- 
 stances may be made available for the same 
 purpose at a less cost. 
 
 Blubber, when it is to be had, is much lower 
 in price than either of the oils; but then its 
 real value is about in the same proportion, as a 
 great part of the blubber consists of earthy 
 matter, which is comparatively useless. Still, 
 compared with the cost of bones, the difference 
 is in favour of the mixture of oil and ashes ; 
 and a time may arrive when a sufficient sup- 
 ply of bones will be unattainable ; and, indeed, 
 even now, their cost is a serious obstacle to 
 their use : and it is, therefore, desirable in every 
 way to be enabled to point out a substitute for 
 their use. 
 
 Bones. — The remarks made when speaking 
 of the phosphate of lime, (page 105) will ex- 
 plain the action of bones on vegetation. Their 
 beneficial effects are attributed entirely to the 
 presence of that substance, as whether new or 
 old bones are made use of, the effects produced 
 are the same. 
 
 It is a curious fact, and one which is cha- 
 racteristic of the energy with which all sources 
 of commerce are pursued in this country, that 
 the wild cattle existing in the extensive plains 
 
CHARCOAL. 119 
 
 of South America, are slaughtered often for no 
 other purpose, than that their bones, ground 
 into dust, may be exported for the supply of the 
 turnip-fields of England.* 
 
 This branch of our trade, however, may 
 have to be discontinued, as it is expected that 
 a substitute will be found for the use of bones in 
 apatite, or native phosphate of lime, a sub- 
 stance existing abundantly in Spain ; a; cargo 
 of which is either arrived, or is expected to 
 arrive in this country, when the experiment 
 will, we have no doubt, be fairly tried. Even 
 if a supply from this source should fail, there 
 is little doubt but that phosphate of lime might 
 be manufactured at a sufficiently low price to 
 suit the purposes of agriculture. 
 
 Chalk. — See carbonate of lime, (p. 100.) 
 
 Charcoal — This substance is destined for 
 the future, to rank amongst the most valuable 
 accessories that the farmer possesses; in its 
 natural state it is indestructible, and no length 
 of time produces the least effect on its sub- 
 stance, or impairs any of its original attri- 
 butes; and this will be explained to be one 
 of its most valuable properties to the agricul- 
 turist. 
 
 In its natural state it is black, perfectly in- 
 sipid, and free from smell, insoluble in water, 
 brittle, and easily pulverized ; and when secured 
 in close vessels, and the contact of the air en- 
 tirely removed from it, it is unchanged by any 
 degree of heat. 
 
 The peculiar property of charcoal, and the 
 
 * Daubeny. 
 
120 CHARCOAL. 
 
 only one that makes it useful in connexion 
 with the subject of manures is, its powers of 
 absorbing various gases in the pores of its 
 structure, and subsequently yielding them to 
 moisture. 
 
 It i« proved beyond all doubt, that pure 
 fresh burnt charcoal possesses the power of 
 absorbing 90 times its volume of ammonial 
 gas, and 35 times its volume of carbonic acid 
 gas. It has the power also of absorbing the 
 other gases, but it is needless to specify them 
 here, as the two above quoted are those only 
 which produce any effect in relation to agri- 
 culture. This property of charcoal is entirely 
 a mechanical effect, and is not due to any che- 
 mical action resulting between the charcoal 
 and the gas, as the gases so absorbed are readily 
 given out when the charcoal is subjected to the 
 heat of boiling water. 
 
 The densest and heaviest kinds of charcoal 
 possess this capacity of absorption in the high- 
 est degree •; and, consequently, charcoal pre- 
 pared from boxwood is the best for this pur- 
 pose : but this power in all cases is much 
 diminished by reducing the charcoal to a state 
 of powder; it should, therefore, when used for 
 agricultural purposes, be just broken, so as to 
 allow of its equal distribution over the surface 
 of the soil. In this state it will absorb any 
 gas with which it may come in contact; and 
 if any manure has been applied containing 
 ammonia in its free state, that is liable to pass 
 off in a gaseous form, the charcoal will absorb 
 it as it rises, and retain it until the first rain, 
 when the gas will be dissolved by the water 
 
CHARCOAL. 121 
 
 and carried into the soil, there to be applied 
 for the assimilation of plants, and the removal 
 of the gas by the rain from the charcoal re- 
 stores its original power of absorbing gas ; so 
 that this substance, when applied to the soil, 
 acts as a constant reservoir for these valuable 
 gaseous substances, a property which neither 
 time nor any circumstance can alter. 
 
 Even when, in the course of cultivation, the 
 charcoal originally applied on the surface of 
 the land is ploughed under the surface, even 
 there it does not lose its power of absorbing 
 the gases, but carries on its operations with 
 undiminished energy. 
 
 Charcoal, thus applied, derives a supply of 
 these gases from other sources than the soil, 
 thus, if rain falls, and all rain generally con- 
 tains a portion of ammonia, it is at once ab- 
 sorbed by the charcoal, or at least that portion 
 which under other circumstances would be 
 carried off during the evaporation of the mois- 
 ture from the surface. It is to this peculiar 
 property, that the whole benefit of charcoal as 
 a manure is to be attributed ; it is, however, so 
 extensively useful that a few of its applications 
 are subjoined, in the belief that circumstances 
 are daily occurring in which its application 
 may be useful. 
 
 ** Charcoal resists the putrefaction of animal 
 substances. A piece of flesh, that is already 
 tainted, may have its sweetness restored by 
 rubbing it daily with powdered charcoal, and 
 it may be preserved sweet for some considera- 
 ble time by burying it in powdered charcoal ; 
 which, however, it is necessary to renew daily. 
 
122 FARM-YARD MANURE. 
 
 ** Putrid water is also restored by the use of 
 this substance, and water may be kept un- 
 changed at sea or elsewhere by perfectly char- 
 ring the inner surface of the casks used to 
 contain it. 
 
 "It produces also a remarkable effect, in 
 destroying the taste, colour, and smell of many 
 animal and vegetable substances. Common 
 vinegar by being boiled in it is rendered per- 
 fectly limpid. Rum, and other ardent spirits, 
 possessing a peculiar flavour and colour are de- 
 prived of both, by maceration with charcoal; and 
 lastly, putrid animal matter and air, contami- 
 nated with offensive fumes, are completely de- 
 prived of their odour by contact with this sub- 
 stance." — {Henry's Chemistry,) 
 
 Nothing can be added to this information 
 to increase either its general or individual 
 utility to the agriculturist, and it is hoped 
 that the arguments now given, will not be en- 
 tirely without their effect in inducing its use. 
 
 Bung — Farm-yard. — It would be altogether 
 foreign to the purpose of this work to enter 
 into a description of the various means that 
 have been suggested from time to time for im- 
 proving the management of the farm-yard with 
 reference to the dung. It must suffice here if 
 a general description is given of the contents 
 of farm-yard manure, and of the best means 
 for rendering such manure more valuable, by 
 avoiding the loss that now generally ensues. 
 
 Farm-yard manure, then, in its general mean- 
 ing, implies a mixture of vegetable matter and 
 animal excrement in a state of decay. Vege- 
 table matter, as we have previously seen, (p. 
 
FARM-YARD MANURE. 123 
 
 47,) yields in its decay carbon, which, provided 
 it takes place under the ground or in or near 
 situations where other plants are vegetating, 
 is at once absorbed by them and assimilated in 
 their growth ; but if this decay is allowed to 
 take place, as too frequently is the case, in situ- 
 ations where its carbon cannot be assimilated, 
 then such carbon is entirely lost. 
 
 Animal excrement, urine, for instance, the 
 principal ingredient in farm-yard manure, 
 yields nitrogen, and both these substances, the 
 nitrogen and carbon, are of primary impor- 
 tance in the growth of plants. It is, therefore, 
 a question of considerable importance, how 
 both these substances, arising from the decay 
 of vegetable and animal matter, can be so pro- 
 duced, that all shall be absorbed and none be 
 allowed to pass off in the gaseous state to the 
 atmosphere. How, indeed, all may be saved 
 and no part wasted? The query then is, how 
 is this desirable arrangement to be produced ? 
 If straw, for instance, mixed with animal ex- 
 crement were applied to the land in its fresh 
 state, and then to be ploughed in, there can be 
 no doubt but that all the carbon it may contain 
 would be absorbed by the soil and none would 
 be lost; but against this it may be fairly stated, 
 that the time such straw would require for its 
 decomposition, would render its effect in some 
 measure useless, as the carbon yielded is prin- 
 cipally necessary to plants in the early stage 
 of their growth, when a rapid supply is neces- 
 sary ; and which, in this latter case, certainly 
 would not be the case; but if, as is too fre- 
 quently the case, the stable litter and other 
 
124 FARM-YARD MANURE. 
 
 farm-yard manure is put together in a heap 
 and exposed to the weather, the moisture thus 
 absorbed causes immediate decomposition, and 
 the heap is observed to be reeking with steam 
 during the whole day. This steam contains 
 the most valuable portion of the heap, and the 
 fermentation which this indicates should at 
 once be stopped, as the ammonia arising from 
 the decomposition of the urine is then volati- 
 lized (that is, flying off in the shape of vapour) 
 and escaping at an immense sacrifice of real 
 manure to the farmer. To prevent this, the 
 manure heaps should always be kept dry, as 
 moisture inevitably induces decomposition, and 
 when once this has commenced it is diflicult 
 to stop its progress. 
 
 When such decomposition has commenced, 
 the heaps should be spread open, so as in no 
 part to be more than four inches thick, the de- 
 composition would then, provided no moisture 
 reached it, be stayed, and the manure might be 
 kept in this state until wanted for use. Or, if 
 this plan is not feasible, after having been 
 spread out, some gypsum or charcoal fresh 
 burnt should be spread in layers throughout 
 the heap, and this would collect all the ammo- 
 nia, which under other circumstances would be 
 volatilized. 
 
 It cannot be too strongly impressed on all 
 agriculturists, that by allowing their farm-yard 
 manure to become rotten before it is used, they 
 are suffering a severe loss of fertilizing matter, 
 from the combined evaporation of the ammo- 
 nial gases from its surface, and the washing 
 away by means of the rain of the saline parti- 
 
FARM-YARD MANURE. 125 
 
 cles it once possessed, and that no heaps should 
 be allowed to ferment and decompose until a 
 few days prior to their application to the soil. 
 The utility of allowing decomposition thus to 
 commence, is that the ultimate decay of the 
 manure is thereby hastened. Whereas if this 
 decomposition had not so commenced before its 
 application to the soil, a much longer time 
 would be necessary for its decay therein. 
 
 Decomposition once having commenced in a 
 dung heap, it is only to be arrested by being 
 separated and kept dry, but when spread on 
 the land, the natural moisture of the earth, in- 
 dependently of rain, would be sufficient for its 
 renewal. 
 
 As far then as these observations have al- 
 ready extended, it seems desirable that farm* 
 yard dung should be applied to the land, when 
 decomposition has already decidedly com- 
 menced, but when it has not been carried so far 
 as to have destroyed the vegetable structure. 
 In this state we conceive it to be best adapted 
 for promoting the growth of other plants; the 
 moisture of the ground will facilitate its decay, 
 and the supply of carbon will, from its conti- 
 nued decomposition, be uniform and abundant. 
 And if no unnecessary time is allowed to 
 elapse, from the time of its application to the 
 soil to that of its being ploughed in, very little, 
 if any, of its fertilizing properties will be lost. 
 
 The saline particles also which the refuse 
 matter of all plants contain, will, when they are 
 thus decomposed, be gradually dissolved in the 
 soil, and will furnish their quota for the nutri- 
 tion of other plants, and none wull be wasted. 
 12 
 
12G FARM-YARD MANURE. 
 
 The animal matter too, such as the solid 
 fseces, and the urine with which we assume the 
 straw to be saturated, w^ill equally be decom- 
 posed during the decay of the vegetable matter, 
 and will afford a valuable supply of saline mat- 
 ter to the growing plant. 
 
 It may not be irrelevant to the subject now 
 under consideration to note : — That the relative 
 value of the manure of all animals, whether 
 solid or liquid, depends in very great measure 
 on the food they eat. If, for instance, the flock 
 of sheep on a farm, live wholly on green food, 
 such as grass and turnips, or on hay, it follows, 
 as a matter of course, that the excrement can 
 only consist of the refuse matter of such food 
 not assimilated by the animal, and in the case 
 now before us, as the food consists almost en- 
 tirely of carbon, and a few earthy matters, so 
 must the excrement also consist of carbon. But 
 if, instead of these carbonaceous matters, the 
 food of the sheep consists of corn or linseed cake, 
 or other substances containing nitrogen, then 
 wdll the excrement contain the nitrogen not ne- 
 cessary for the supply of the body; and arguing 
 on the reasons we have before given, it is con- 
 sequently assumed, that the excrement so 
 voided, must be more valuable as a manure. 
 
 Hence, it is a question to be determined by 
 agriculturists themselves, as to whether it 
 would not be more to their advantage, to keep 
 their flocks and cattle generally on more nutri- 
 tious food, if only for the sake of the increased 
 value of the manure. It may be thought per- 
 haps presumptuous for an opinion on the sub- 
 ject to be off"ered here, but, notwithstanding, 
 
BIRD S DUNG. 127 
 
 we would respectfully beg to say, that in our 
 estimation such a proceeding would amply re- 
 pay the increased cost. 
 
 Bird's Dung. — The dung of all birds has 
 always been esteemed as a valuable manure, 
 and its excellence, in great measure, depends 
 on the quantity of lime it contains. 
 
 In the excrement from poultry, this sub- 
 stance is not equally abundant as in that pro- 
 duced by the sea-fowl, which live entirely on 
 animal matter. 
 
 The excrement of these latter birds, is found 
 on many of the rocky and uninhabited isles of 
 our northern coasts ; but the moist and humid 
 atmosphere of this climate, combining with 
 the heavy rains of winter to wash it away as 
 soon as formed, has prevented an extensive 
 deposite of this substance from taking place. 
 
 in the more genial climes, however, of the 
 tropics, where the sun's raj^s have dried this 
 excrement as soon as dropped, an inexhausti- 
 ble supply exists ; and as its use as a manure 
 has been recommended by various persons, 
 from the time when Sir Humphrey Davy first 
 called attention to it in 1S04, to the present 
 time, a cargo of this substance, known by the 
 name of Guano, has this year (1841) been im- 
 ported, with a view to its adoption here as a 
 manure. 
 
 This substance is collected on the unin- 
 habited and other islands of the South Sea, 
 where sea-fowl in immense flocks have been 
 congregated from time immemorial, and so 
 abundant is it, that the whole soil, in some 
 cases to the depth of many feet, is found to be 
 
128 GUANO. 
 
 composed entirely of this substance. It has 
 already been used as a manure on the conti- 
 nent of South America ; and there seems to be 
 no doubt, but that its use will prove highly 
 beneficial here, and at all events its merits 
 will now be tested. 
 
 The following statement, affording all the in- 
 formation at present known relative to Guano, 
 is extracted from one of the periodicals of the 
 present day : — ■ 
 
 " Various opinions have been formed as to 
 the origin of Guano, by some it is considered 
 a mineral production, by others the excrement 
 of sea-birds. At first sight, and without a care- 
 ful examination, it is difficult to decide on this 
 question. The immense quantities which have 
 been removed from, and which are still to be 
 found upon the islands and rocks off the coast 
 of Peru, as well as upon the coast itself, its 
 weight, the red colour of oxide of iron, and the 
 difficulty of conceiving how any number of 
 birds, however great, could have furnished so 
 inexhaustible a supply, — these circumstances 
 favour the idea of its being of mineral origin. 
 But, on the other side, its physical and chemi- 
 cal characters oppose such a supposition, and 
 would lead us to consider it as an animal pro- 
 duction. The ammoniacal odour which it 
 gives off, the existence of uric, phosphoric and 
 oxalic acids, and of potass, its red colour (dif- 
 fering in intensity in proportion to the time it 
 has been exposed to the air,) its identity of com- 
 position with the white Guano, which is pro- 
 duced daily, the circumstance of its being 
 found only on the coast, and never in the inte- 
 
GUANO. 129 
 
 rior, as well as the bones of these birds, which 
 are used as cutting instruments by the Indians, 
 having been found at some depth below the 
 surface, and the fact of the white Guano as- 
 suming the red colour by time, as observed in 
 the island of Torrecilla, are convincing proofs 
 that the coloured Guano is an animal produc- 
 tion. 
 
 " There are three varieties of Guano, the red, 
 the dark gray, and the white. The first two 
 are met with in the Isles of Chinca, near Pisco, 
 at Iquique, and on the hill of Pica. The term 
 " Guano of Iquique," is sometimes used, from 
 its having been first procured from the island 
 of that name. This island is situated about 
 400 yards from the port of Iquique; it is about 
 a half a mile long, and about 200 yards broad, 
 and furnished large quantities of Guano for 25 
 years, when it became exhausted. The hill 
 of Pica is very high, and is covered with 
 Guano down to the water's edge, while that 
 side does not face the sea, is of sand and gravel. 
 In this hill or rock, a silver mine was formerly 
 worked, but no trace of Guano was found 
 during the excavation. The adjoining hills 
 on either side are of sand, which is carried by 
 the winds, and covers up the Guano, to remove 
 which the sand is first taken away, and deep 
 excavations made, the Guano extending nearly 
 a quarter of a league in length, and 300 yards 
 in depth.* 
 
 *' It is likewise found at St. Lobos, about 
 three leagues to the south of Pica, but as the 
 
 * Query — 300 yards from the shore inland? 
 12* 
 
130 GUANO. 
 
 anchorage hereabouts is dangerous, little busi- 
 ness is done. 
 
 " The white Guano is considered the most 
 valuable as being fresher and purer. It is 
 found on nearly all the islands along the coast. 
 
 <* These varieties of Guano have different 
 prices; the red and dark gray are worth 2^. Sd. 
 the cwt.; a higher price is given for the white, 
 on account of its greater scarcity; it is sold in 
 the Port of Mollendo at 3^. 6d. the cwt., and 
 at times, as for instance during war, it has 
 fetched as high a price as 125. 
 
 *<It has been observed, that in the Isles of 
 Islay and Jesus, in those years when many 
 birds have assembled here, from 400 to 500 cwt. 
 have been taken away. Of late years there 
 has been a diminution in the supply, from the 
 birds having left these islands, owing to the 
 following causes; the excessive heat of the 
 late summers, the scarcity of food> and the 
 number of vessels in port at one time, which by 
 the noise occasioned, cannot fail to have driven 
 them away; on which account, the proprietors 
 of the Guano ground of Jesus, obtained sche> 
 dules from the court of Spain, to prohibit ves- 
 sels of war from touching at this port, since on 
 their arrival all the birds immediately disap- 
 peared, to the prejudice of the proprietors; and 
 since the opening of the port of Islay, the birds 
 have nearly deserted the adjacent inlets. 
 
 "That careful and enterprising traveller, 
 Baron Humboldt, after his voyage to Peru, sent 
 a portion of Guano for analysis to the cele- 
 brated French chemists, Fourcroy and Vau- 
 quelin. 
 
GUANO. 131 
 
 **The coloured Guano passes to the grajr; 
 has a rather strong am moniacal odour, and is 
 heavy ; dissolves in acids with effervescence; 
 a certain quantity being dissolved in water im- 
 ports an odour similar to that of urine; its fla- 
 vour is saltish and pungent; it gives precipitates 
 with ammonia, the oxalate of potass, the nitrate 
 of silver, with the subcarbonate and prussiate 
 of potass. The solution being evaporated, 
 cubic crystals of muriate of soda, and of muri- 
 ate of ammonia are left, kept for some days it 
 undergoes no alteration, and only acquires a 
 strong smell and taste. The Guano being cal- 
 cined, ammoniacal vapours are given off in 
 abundance, leaving a very light carbon. Four- 
 croy and Vauquelin met with uric acid, in part 
 saturated with ammonia and potass, phosphoric 
 acid combined with the same basis and wnth 
 lime, small quantities of the hydrochlorates of 
 ammonia and potass, a small quantity of fatty 
 matter, and of quartzy and ferruginous sand. 
 But in an analysis which the writer of this pa- 
 per has recently made, he found it to contain a 
 considerable quantity of the muriate of soda, of 
 ammoniacal salts, and of iron. The white 
 Guano is of the same composition, except that 
 it is free from sand, has not so powerful a smell 
 (from not having undergone spontaneous de- 
 composition) is lighter, leaves more residue in 
 the crucible, and contains a small proportion of 
 iron and muriate of soda. 
 
 *'The date of the discovery of the Guano, 
 and of its introduction as a manure in Peruvian 
 agriculture is unknown, though no doubt ex- 
 ists as to its great antiquity. In many parts of 
 
132 GUANO. 
 
 America, where the soil is volcanic or sandy, 
 no produce would be obtained without the 
 Guano. 
 
 "It has been calculated that from 12,000 to 
 14,000 cwt. are annually sold in the port of 
 MoUendo, for the use of the country around the 
 city of Arequipa. In the province of Taracapa, 
 and in the valleys of Tambo and Victor, the 
 consumption should be something more; as 
 wheat, all kinds of fruit trees, and plants, with 
 the single exception of the sugar cane, are ma- 
 nured with the Guano, which is not the case 
 with the district of Arequipa, where maize and 
 the potatoe alone require it. In the district of 
 Arequipa, three cwt. of the Gnano is spread 
 over an extent of 5000 square yards, but in Ta- 
 racapa, and in the valleys of Tambo and Victor 
 five cwt. are required." 
 
 The analysis of Guano yields: 
 
 Phosphate of lime 
 
 Sulphates and muriates 
 
 Lythic acid 
 
 Ammonia 
 
 Other organic matter . 
 
 30^ parts. 
 3 
 
 15 
 15 
 361 " 
 
 It is recommended either to be sown or 
 drilled with the seed, or as a top dressing, and 
 in whatever way it is used, the subsequent ap- 
 plication of a bushel of powdered charcoal is 
 also recommended, as producing effects on the 
 second crop quite equal to those on its first ap- 
 plication. 
 
 It need hardly be stated here, that the use of 
 the charcoal is to absorb the ammoniacal gases, 
 w^iich otherwise would escape and be \^asted. 
 
dogs' dung. 133 
 
 It is strongly recommended for wheat, bar- 
 ley, oats, turnips, clover, and hops. The quan- 
 tity to be used per acre from 1 to 2 cwt. The 
 price in November, 1841, is 26s. per cwt. in 
 London. 
 
 Dogs^ Bung. — When the dog is fed on flesh 
 and bones only, the excrement yields upwards 
 of 95 per cent, of phosphate of lime, and it is a 
 question to be solved by experiment, whether 
 the use of this manure, limited as the supply 
 may be, would be beneficial. Reasoning from 
 the contents we should say. it would, but it 
 might be improved by a mixture of charcoal, 
 saturated with putrid urine, to furnish the am- 
 moniacal salts. 
 
 Gas Liquor, — In the manufacture of gas, by 
 submitting coal to distillation in iron retorts, 
 besides the tar, a solution of carbonate of am- 
 monia is produced in a liquid form, and is pro- 
 perly called ammoniacal liquor. In many 
 cases this liquor is considered entirely as a re- 
 fuse; in others, in the vicinity of manufactures, 
 it is purchased by soap-boilers ; and in a few 
 cases it has been used as a manure ; and there 
 can be little doubt from the saline property that 
 it contains, that by judicious treatment it may 
 be rendered a very valuable fertilizer. 
 
 Carbonate of ammonia, as before noticed, is 
 a valuable stimulant; but if the ammoniacal 
 liquor is applied to the soil in this slate, the am- 
 monia would readily fly off in the state of va- 
 pour, and no benefit would be derived by the 
 soil. To obviate this, it should first be con- 
 verted into a sulphate of ammonia; that is, am- 
 
134 GAS LIQUOR. 
 
 monia combined with sulphuric acid. In this 
 state the salt has entirely lost its volatile pro- 
 perties, whilst it retains its solubility, and is 
 equally, if not more, fertilizing in its effects. 
 
 To convert this carbonate of ammonia, it is 
 only necessary to add a sufficient quantity of 
 sulphuric acid to the ammoniacal liquor, until 
 all the effervescence caused by the acid has 
 ceased. When this is effected, the carbonic 
 acid gas has passed off, and the residue is an 
 impure sulphate of ammonia. Or it may be 
 made by mixing gypsum with the gas liquor, 
 and allowing it to remain a few hours to decom- 
 pose. 
 
 In its operation on plants, the sulphate of 
 ammonia, when applied to the land, is dissolved 
 by the first moisture, and carried into the soil, 
 where it is absorbed by the roots of the plants ; 
 the ammonia is then decomposed, and the ni 
 trogen it contains is assimilated in the way we 
 have previously described (p. 62.) 
 
 It may be objected that this mode of pro- 
 ceeding is too expensive for general use ; but 
 as the sulphuric acid is one of the cheapest 
 acids that exists ; and as a pound (costing from 
 2d to 2d) of it will convert the carbonate con- 
 tained in three gallons of gas liquor into a sul- 
 phate, and thereby furnish 30 oz. or nearly 
 2 lbs., of sulphate of ammonia, we think, in- 
 deed we feel assured, that the additional quan- 
 tity of ammonia thus fixed in the soil would 
 amply repay the outlay. 
 
 If the gas liquor is applied in its natural 
 state, a portion certainly of the carbonate of 
 ammonia it contains is absorbed by the earth ; 
 
GAS LiqpoR. 136 
 
 but by far the larger portion would be carried 
 off' by evaporation with the watery parts ; and 
 therefore it is that its conversion into a sul- 
 phate of ammonia, before it is thus applied, is 
 recommended. Or the field may be strewed 
 with gypsum, and the gas liquor may then be 
 sprinkled over it, when a natural decomposi- 
 tion will take place, — the carbonic acid gas of 
 the ammonia would unite with the lime, and 
 form carbonate of lime ; and the sulphuric acid 
 of the lime would unite with the ammonia and 
 form sulphate of ammonia. Either of these 
 plans is perfectly feasible, and we again re- 
 peat that a handsome return m?ij be antici- 
 pated from a judicious outlay in either of these 
 processes. 
 
 There is another refuse at gas-works, that 
 may be used perhaps with advantage, — the 
 lime through which the gas is passed for the 
 purpose of purifying it; but, as it is exceed- 
 ingly caustic in its effects, great care must be 
 used. In the state in which it is sold at the 
 gas-works, it exists as a hydro-snlphuret of 
 lime; but on being exposed to the air, this pro- 
 perty is lost, and it would eventually be- 
 come a sulphate of lime (gypsum,) when 
 it would of course become beneficial. But 
 it is still a question, although there are some 
 facts adduced to the contrary, whether on 
 the whole it can be considered as beneficial 
 in its caustic state. 
 
 Liquid Manure. — and by this we mean the 
 running of all stables, cow-sheds, and farm- 
 
136 * NIGIJT SOIL. 
 
 yards, — is too often allowed to be wasted, and, 
 in too many cases, is felt to be a nuisance in- 
 stead of being regarded as a most prolific fer- 
 tilizer. 
 
 In the chapter on Urine we shall enter fully 
 into its value as a manure. And as this liquid 
 manure is composed principally of urine, 
 largely diluted with water, and impregnated 
 with other saline matters, which the rain has 
 washed from decaying vegetables, we trust 
 that its benefits wuU then be at once recognised. 
 
 Every farm-yard, every stable, every shed 
 where cattle are kept, ought to be so arranged, 
 as for the running of each to be preserved. 
 
 The liquid manure, thus obtained, should 
 either be carried away and spread over the 
 fields ; or, better still, it may be allowed to be- 
 come putrid, and then mixed in the compost 
 heap to serve in the formation of nitre, (p. 83.) 
 
 In any case it ought not to be wasted. Its 
 value as a fertilizer cannot be overrated ; and 
 it is hoped that England will soon follow the 
 example of her continental neighbours in the 
 use of this manure. 
 
 ISight Soil. — The value of night soil as a 
 manure, principally depends upon the pre- 
 sence of ammonia ; and this ammonia is almost 
 entirely derived from the urine with which 
 night soil is always mixed. 
 
 Berzelius, in his analysis of the solid excre- 
 ment, gives the proportion of nitrogen as vary- 
 ing from 1| to 5 per cent., and about 15 per 
 cent, of ashes, principally composed of the 
 phosphate of lime and magnesia. In all cases, 
 however^ night soils is richer in nitrogen than 
 the excrement of any other animals. 
 
NIGHT SOIL. 13? 
 
 That the use of this manure must be benefi- 
 cial there can be, and is no doubt; but it is 
 equally true, that in the way in which it is 
 generally prepared, one-half or more of its 
 valuable contents is lost : but even with all this 
 loss, as it still is a very powerful manure, par- 
 ties are generally satisfied with the result ; 
 although, properly treated, its fertilizing 
 power might be increased five or six times. 
 
 The addition of lime, under any circum- 
 stances, is very prejudicial, as the ammonia is 
 by this means at once liberated, the carbonic 
 acid of the ammonia at once combining with 
 the lime, and setting free the ammonia in a 
 volatile state. 
 
 The beneficial results arising from soil so 
 prepared, are attributed entirely to the phos- 
 phates which they still contain ; for all the 
 ammonaical salts have been decomposed, and 
 their ammonia expelled. 
 
 It is suggested, in the absence of any other 
 information on the subject, that the best means 
 of preparing the night soil without loss, would 
 be to mix the mass, after it has been removed 
 to some convenient spot, and allowed to putrefy, 
 with the strongest sulphuric acid, until all 
 effervescence, consequent on such mixture, had 
 ceased. It may then be either left to dry of its 
 own accord, or it may be mixed with good 
 mould as free from lime as possible, or charcoal, 
 and in this state freely exposed to the currents 
 of air to dry it. But it should be protected 
 from rain by a roof of some kind or other, as 
 the moisture is doubly injurious, not only in 
 13 
 
138 SOOT. 
 
 preventing its becoming dry, but by wasting 
 away also. the saline matter it contains. 
 
 ClarMs Dessicated Compost, Alexander's 
 Ohio Fou, PoitevirPs Manure — are all, it is be- 
 lieved, the excrements solid and liquid, mixed 
 together, dried in a somewhat similar manner; 
 care being taken to fix the ammonia, and not 
 allow it to escape in the state of vapour. The 
 beneficial results arising from the use of these 
 manures, is very decided, and the numerous 
 proofs of their efficacy, should only act as a 
 stimulus to all agriculturists, not to allow the 
 waste, with respect to this manure, longer to 
 continue. 
 
 It is abundant, cheap, and very fertilizing ; 
 and we know not that more can be said, to in- 
 duce parties interested at once to adopt, not 
 only its use, but its preparation. One consi- 
 derable advantage, to be derived from its use as 
 a manure is, that it contains no seeds, which 
 when applied to the soil produce weeds ; an in- 
 convenience to which the excrement of horses 
 and oxen is liable, from the circumstance of 
 various kinds of seeds passing uninjured with 
 the faeces, and which materially detracts from 
 their value as a manure. 
 
 Potash. — See page 79. 
 
 Salt. — See page 86. 
 
 Salpetre. — See page 80. 
 
 Soda. — See page 85. 
 
 Soot has been extensively used as a manure 
 for some years past, and we believe with un- 
 varying success. 
 
 It owes its fertilizing power chiefly to the 
 ammonia it contains, which being dissolved by 
 
URINE. 139 
 
 moisture and carried into the soil, produces 
 the same effects as we have noticed when speak- 
 ing of nitrogen. 
 
 A portion also of the beneficial effect of this 
 application, may be attributed to the charcoal 
 which partly composes it; and which, acting 
 as an absorbent of the ammonia contained in 
 the atmosphere may serve to increase its effect. 
 Another portion may be attributed to the small 
 quantity of saline matter it contains ; but its 
 principal use as a fertilizer is derived from the 
 presence of ammonia. 
 
 Urine — "■ When it is considered," says Lie- 
 big, *'that with every pint of urine, a pound of 
 wheat might be produced; the indifference 
 with which this liquid excrement has been re- 
 garded is quite incomprehensible." 
 
 We can here only join in expressing our sur- 
 prise at such neglect; but we would at the same 
 time fain hope that such neglect has arisen en- 
 tirely from ignorance of its value, and in the 
 zealous endeavours that are now making by 
 agriculturists at large, and the zeal, energy, 
 and ability that is now displayed, we may 
 fairly anticipate a juster appreciation of this 
 manure for the future. 
 
 That we do not overrate the value of this 
 manure, may be proved from the following 
 results of the analysis of 100 parts of wheat 
 manured in different ways, and which places 
 human urine in the very first place as to value. 
 
 We have before stated that the weight and 
 value of wheat as an article of food, depends'on 
 the quantity of gluten it contains, and this 
 fact admitted, no other argument is required 
 
140 URINE. 
 
 to convince us of the superiority of urine as a 
 manure:* 
 
 
 Gluten. 
 
 Starch 
 
 100 parts of wheat manured with 
 
 
 
 Human urine (dried) yielded 
 
 35.1 
 
 39.1 
 
 Bullock's blood (dried) . 
 
 34.2 
 
 41.3 
 
 Human faeces (dried) - 
 
 33.1 
 
 41.4 
 
 Sheep's dung . 
 
 22.9 
 
 42.8 
 
 Pigeon's dung . 
 
 12.2 
 
 63.2 
 
 Cow's dung 
 
 12.0 
 
 63.3 
 
 Vegetable humus 
 
 9.6 
 
 55.9 
 
 The same soil not manured 
 
 9.2 
 
 66.7 
 
 We have elsewhere (page 64) endeavoured 
 to show, that all excrement partakes of the na- 
 ture of the food; that if food, consisting almost 
 wholly of nitrogen, is consumed, that such ex- 
 (5rement wall principally consist of the nitro- 
 gen not required to supply the waste of the 
 body. That if food principally consists of 
 substances in which carbon predominates, that 
 the matter voided as excrement neither is not, 
 nor cannot be so rich in nitrogen as in the pre- 
 ceding case : the rule holds good throughout 
 all creation; and therefore, as man is a car- 
 nivorous animal, and lives in great measure on 
 the flesh of animals, a substance almost en- 
 tirely composed of nitrogen, human urine is 
 much richer in this substance, nitrogen, than 
 in animals living exclusively on vegetables. 
 The analysis of these matters accordingly 
 proves that human urine contains four times 
 more fertilizing matter, than the urine of horses, 
 cows, and sheep. 
 
 * Analysis of Hermbstoedt, quoted by Professor Daubeny. 
 
URINE. 
 
 141 
 
 In all the remarks then that follow, we must 
 be considered as speaking of human urine; but 
 the same arguments will apply to the urine of 
 all animals, only in lesser proportion. 
 
 And it must be again repeated that the liquid 
 excrement of all animals is infinitely to be pre- 
 ferred as a fertilizer to the solid excrement, the 
 urine in all cases containing all the soluble 
 salts which are thrown off from the body as 
 waste matter; such as the ammoniacal salts, 
 the phosphates of soda, potash, and magnesia, 
 the substances which are now recognised as 
 constituting the ingredients of all kinds of 
 grain, and which are essential both to their 
 growth and development, and for supplying 
 the nutritive matter of the grain. 
 
 Berzelius gives, as the contents of 1000 parts 
 of human urine in his elaborate analysis of the 
 fluid, 
 
 Urea 
 
 -30 
 
 Lactate of ammonia and animal matter 17^ 
 
 Uric acid 
 
 i 
 
 Sulphate of potasli 
 
 31 
 
 Sulphate of soda . 
 
 .3i 
 
 Phosphate of soda 
 
 3 
 
 Pliosphate of ammonia . 
 
 H 
 
 Chloride of sodium 
 
 4i 
 
 Muriate of ammonia 
 
 H 
 
 Phosphate of magnesia and lime 
 
 1 
 
 Water, mucus, and silex 
 
 933 
 
 parts 
 
 " If, from the above analysis, we take the 
 urea, lactate of ammonia, uric acid, the phos- 
 phate and muriate of ammonia, one per cent, 
 of solid matter remains, consisting of ammo- 
 niacal salts, which must possess the same 
 
 13* 
 
142 URINE. 
 
 action, whether they are brought on a field dis- 
 solved in water or urine." Hence the power- 
 ful influence of urine must consist in its ammo- 
 niacal salts. Now, when urine is allowed 
 spontaneously to putrefy, one portion of the 
 ammonia unites with the lactic acid to form 
 lactate of ammonia, and another becomes vola- 
 tile in the state of carbonate of ammonia. 
 
 The formation of this carbonate of ammonia 
 entirely alters the state of the urine, rendering 
 it an alkali, instead of an acid, which it is in 
 its natural state, and this explains why putre- 
 fied urine is to be preferred as a manure to 
 urine in its fresh state. Now the great object 
 is to fix this carbonate of ammonia, or at all 
 events the ammonia, in the soil. 
 
 If the urine is applied as a manure in this 
 state, that is, with the lactate and carbonate of 
 ammonia in solution, the latter salt, from being 
 volatile, will evaporate with the watery parts 
 of the fluid ; and the loss which would accrue 
 from this mode of using it, would amount to 
 nearly ono half of the weight of the urine em- 
 ployed. So that, if by any means we can fix 
 the ammonia, that is, deprive it of its power to 
 fly off" with the evaporation of the watery parts 
 of the urine, we shall increase its action two- 
 fold. This object may be effected in a variety 
 of ways. If a field is strewed with fresh burnt 
 gypsum (sulphate of lime) and then the putre- 
 fied urine be applied on its surface, the gypsum 
 will absorb and decompose the carbonate of 
 ammonia, and the carbonic acid gas thus dis- 
 engaged, will unite with the lime to |brm car- 
 bonate of lime, and the sulphuric acid of the 
 
URINE. 143 
 
 lime will unite with the ammonia to form sul- 
 phate of ammonia, and this salt will remain in 
 the soil and not be volatilized. 
 
 But a simpler way still is to mix the gyp- 
 sum with the putrefied urine, and thus effect 
 the double decomposition above described be- 
 fore distributing it on the soil. 
 
 The quantity necessary will of course de- 
 pend on the quantity of carbonate of ammonia 
 the urine may contain, and this not only varies 
 with every stage of putrefaction, but depends 
 also on the way in which it has been kept ; and 
 again, on the quality of the urine itself, no very 
 definite quantity therefore can be named. But 
 an easy way of knowing how much gypsum to 
 put to a certain quantity of urine is to add it 
 constantly at intervals of a few hours (taking 
 care to stir the mixture well occasionally) as 
 long as any volatile smell, similar to hartshorn, 
 escapes, the absence of which will be a sure test 
 that the ammonia has lost its volatile property, 
 and has become, to use a chemical and expres- 
 sive term, fixed. 
 
 Chloride of lime may be used for the like 
 purpose, but being more expensive than the 
 gypsum, it would not of course be resorted to. 
 
 Dried peat, tanner's bark, sawdust, turf and 
 other similar substances, may be also used 
 for this purpose, but the gypsum is decidedly 
 preferable. 
 
 Sulphuric acid, the oil of vitriol of com- 
 merce, may also be advantageously used to fix 
 this salt, and to do so nothing more is neces- 
 sary than to mix a sufticient quantity of this 
 acid with the putrefied urine until almost all 
 
144 URINE. 
 
 effervescence ceases, keeping it well stirred 
 during the whole of the time, and taking care 
 not to add an excess of acid. In this case the 
 ammonia unites at once with the sulphuric 
 acid to form the sulphate of ammonia ; and the 
 carbon, being disengaged, escapes in the state 
 of a gas. 
 
 Other means might be used to effect the 
 same results as we have here demonstrated ; 
 but it is needless to specify them, as those we 
 have already detailed combine great facility as 
 well as extreme cheapness. 
 
 Having thus specified the change that takes 
 place in the state of urine ; the best manner 
 for converting the ammonia for the purposes of 
 agriculture ; we shall suggest the best means 
 of practically using this manure on a farm. 
 
 The first thing necessary is to procure a 
 supply of urine. But if due care is used to 
 save all that is now wasted, no farm need be 
 in want of it. 
 
 The supply being obtained, it should be 
 placed in large casks or tanks, under cover, 
 until the volatile smell of the ammonia indi- 
 cates that decomposition has taken place. 
 When this occurs, it may be either poured 
 over a heap of compost, consisting of coal 
 ashes, charcoal, or gypsum, in any proportions 
 that are the most conveniently obtained, and 
 then allowed to dry, by frequently turning the 
 heap. Care being taken, that if any volatile 
 smell occurs, during this process of drying, that 
 more gypsum be at once added. The volatile 
 ammonia will in this operation be absorbed by 
 the gypsum, and converted into a sulphate of 
 
URINE. 146 
 
 ammonia, and other parts will be absorbed in 
 the gaseous state by the charcoal and the ashes; 
 but all will at once be yielded up to the first 
 moisture, that may come in contact with the 
 heap ; and, therefore, it may be very properly 
 classed amongst those fertilizers which act as 
 a stimulus to the plant. We would, therefore, 
 reasoning from analogy, suggest the use of this 
 dried compost, as an excellent substitute for 
 bones in the drill in sowing turnips. And we 
 are farther confirmed in this opinion, from the 
 fact, that new manure, the urate, only lately 
 introduced, and which is presumed to be pre- 
 pared somewhat in this way, has been found 
 to answer admirably for the purpose intended. 
 The addition, however, of a phosphate of lime, 
 would increase its value in this respect, and 
 render it undoubtedly more valuable than 
 bones for this purpose. 
 
 Another compost heap, which would answer 
 admirably for any purpose almost for which a 
 manure can be required ; that is, either as a 
 stimulant for turnips, as a pabulum for wheat, 
 or white crops — or, again, as a top dressing 
 for either of the above, or for grass, — may be 
 readily formed by mixing long stable litter, in 
 which decay has already commenced, with 
 the burnt ashes of vegetables or wood, in some- 
 what indefinite portions; taking care, how- 
 ever, that the litter should predominate, and 
 then pouring over the heap daily a portion of 
 the putrid urine, and stirring the mass well 
 up together. 
 
 In this heap the ammonia of the urine 
 would be decomposed ; but the nitrogen, the 
 
146 URINE. 
 
 vivifying principle of the ammonia, would 
 unite with the alkaline matter, the soda or 
 potash of the burnt vegetable ashes, to form 
 nitrate of potash or soda : the hydrogen, the 
 other constitutent of ammonia, being given 
 off. 
 
 After what has already been said about the 
 utility of these salts as fertilizers, it will be 
 needless to add more here, than earnestly to 
 recommend every agriculturist to adopt these 
 simple means for the production of two ma- 
 nures, which in value to the farmer cannot be 
 surpassed — both for the facility and economy 
 with which they may be prepared, and which 
 would by their fertilizing properties confer a 
 benefit not only on the farmer, but on the com- 
 munity at large. 
 
 It may be urged as an objection, that in 
 many localities, far distant from towns and 
 cities, that this manure could not be obtained 
 in suflJcient quantities to supply the place 
 of other substances more readily obtained. To 
 this objection we would beg to suggest, that 
 if ever a demand for this article exists, means 
 will be taken to secure a supply ; and, that in 
 such a case as above supposed, the fanrer's 
 wagon would be enabled to load back from 
 the towns or market where their produce must 
 eventually be consumed, with this matter. 
 And farther, they may commence with the 
 supply that is always to be had to some ex- 
 tent on their own farms, and thus verify the 
 results here predicted. 
 
 We will only add, that the urine of one 
 man, taken at its lowest calculation, will pro- 
 
URINE. . 147 
 
 duce in one year, a sufficient supply of nitro- 
 gen for the formation of 800 pounds of wheat, 
 or 900 pounds of barley; a fact of sufficient 
 importance, it is hoped, to induce a trial at 
 least — and this trial fairly made, we have no 
 doubt of the result. 
 
 Indeed, if all the human excrement, now 
 worse than wasted, were applied to the pur- 
 poses of agriculture, animal manure might be 
 entirely dispensed with. But if we look at 
 the subject on an extended scale, and see the 
 thousands of acres now barely cultivated at all, 
 but all of which only require manure to be ap- 
 plied to them, to enable them to yield abun- 
 dant crops ; and if we reflect on the benefits 
 all must derive from such an increase to the 
 real wealth of the country, as the cultivation 
 of these lands would induce ; and farther, that 
 the increased means thus affi)rded, would as 
 certainly induce an increased population, 
 which again in their turn, acting fully up to 
 this system, would again prove another source 
 of wealth and strength to the community, — 
 we may be enabled to estimate in some slight 
 measure, the order and arrangement that ex- 
 ists in nature, for the support of all her crea- 
 tures ; and that it is the neglect of those means, 
 which Providence in its wisdom, has placed 
 at the service of man, and not any imperfec- 
 tion in the grand scheme of the creation, 
 which has induced the impious belief by some, 
 that a redundant population may be a curse 
 instead of a blessing. 
 
 But to return more immediately to our sub- 
 ject. Enough has been said to show that 
 
148 , .URINE. 
 
 ample means exist for bringing all the waste 
 lands gradually into cultivation, that we have 
 the power, if we have the inclination, to do so. 
 And the circumstances of an increased and 
 rapidly increasing population, may compel 
 a much more attentive consideration, than this 
 subject has hitherto received, and one which 
 eventually must lead to the benefit of all 
 classes concerned. 
 
 So much for human urine. The urine of 
 animals, as previously stated, from the nature 
 of their food, contains much less nitrogen than 
 that of man ; but is equally, and in many cases, 
 much more rich in the saline properties it con- 
 tains, such as the phosphates of magnesia, 
 and the salts of potash and soda. They are, 
 therefore, by no means to be neglected, and 
 indeed all the remarks appended to the sub- 
 ject of human urine apply here only with 
 lesser force. We would, however, recom- 
 mend, that all stables, farm-yards, sheds, and 
 other places where cattle are kept, should be 
 so arranged, as for the urine to be saved, and 
 applied in the manner we have before de- 
 scribed. 
 
 Connected with this subject it may here be 
 stated, that the strong volatile smell, which is 
 almost overpowering, when entering a close 
 confined stable, where many horses have been 
 shut up for the night, arises entirely from the 
 volatilizing of ammonia in the urine. 
 
 A very simple, and at the same time a very 
 profitable way, of correcting this injurious 
 atmosphere, is to strew the stable with gyp- 
 sum, which would absorb the ammonia at once 
 
URINE. 149 
 
 as it is formed, and prevent the presence of 
 this gas in the atmosphere. Such an arrange- 
 ment, besides being profitable, as one source 
 of accumulating ammonia, would al.^o act 
 beneficially on the horses so confined, as there 
 can be no doubt, but that breathing such an 
 atmosphere constantly for some hours together, 
 induces a highly excited temperament, which 
 leads to, or at all events very much increases, 
 any local inflammatory action, and renders 
 the cure of such a malady, both difiicuit and 
 uncertain. 
 
 These remarks, however, do not go to the 
 length of suggesting the use of gy[)sum as a 
 cure for such a stable, it is only a niearis of ab- 
 sorbing the noxious principle and turning it to 
 account, but ventilation, to a considerable ex- 
 tent, is the only cure and the best. 
 
 Of the relative value of human urine, when 
 compared with other animal matters, it is cal- 
 culated by Macaire, that 100 parts of human 
 urine are equal, in their fertilizing power, to 
 1300 parts of the fresh dung of the horse, or 
 600 of those of the cow. Nothing more there- 
 fore can be said in favour of this manure ; it 
 must now be left to those who have ihe means 
 of applying and testing its real value. 
 
 In speaking of nitrogen we have fully ex- 
 plained how ammonia acts as the pabulum of 
 plants, but we will here again shortly re[)eat it. 
 
 Ammonia is composed of nitrogen and hydro- 
 gen. Now, when the ammonia, in a state of 
 solution, is absorbed by the spongelets of the 
 roots, decomposition takes place, the nitrogen 
 is assimilated to form the gluten of tho seed, 
 14 
 
150 URINE. 
 
 and the hydrogen either unites with carbon to 
 form the essential or fixed oil of the plant, or 
 is evaporated through the leaves as useless 
 matter. 
 
 That such is the effect of ammonia or nitro- 
 gen, applied under any circumstance, in which 
 the salt is soluble, can be easily demonstrated, 
 by applying it to any crop, when it will 
 speedily assume a dark green colour and lux- 
 uriant appearance, which is the peculiar effect 
 of the nitrogen alone, and which is forcibly il- 
 lustrated in the dark green circles, popularly 
 called fairy rings, which exist on the downs, 
 and which owe their dark colour entirely to 
 the mushroom or fungus spawn, existing under 
 the surface, and which spawn consists almost 
 wholly of nitrogen, and communicates its pro- 
 perty to the grass growing above. 
 
 The specific action of nitrogen also, by en- 
 dowing the plant with greater energy, enables 
 it to assimilate more carbon from the atmo- 
 sphere, and thus the addition of this manure, 
 which is in every respect an essential to plants, 
 gives it a greater power of assimilating another 
 substance of almost equal importance as itself. 
 
 In concluding our notice of this manure we 
 can only repeat that the liquid and solid excre- 
 ment of man used together, and prepared in the 
 way we have described, forms, from its combi- 
 nation of ammonial salts with the phosphates 
 of magnesia and soda, the most valuable com- 
 pound that can be devised, and its extensive 
 use, will confer a double benefit to the farmer 
 and to the public, as well by the removal of 
 matter which is now only considered as a nui- 
 sance, as by increasing the produce of the soil. 
 
WOOLLEN RAGS. 16t 
 
 Woollen Raf^s. — Dr. Henry gives, as the ana- 
 lysis of 100 parts of wool : — 
 
 Carbon 
 
 , 
 
 5o i>arts. 
 
 Oxygen 
 
 . 
 
 . 29d „ 
 
 Hydrogen . 
 
 . 
 
 3 „ 
 
 Nitrogen 
 
 n t 
 
 121 „ 
 
 with perhaps a trace of lime or some earthy 
 matter. 
 
 Having thus given the analysis of wool, it 
 can scarcely be necessary to observe, that the 
 principal value of woollen rags as a manure 
 depends on the 55 parts of carbon in every 100 
 that they contain, which by the slow decay of 
 the sjtructure of the substance is very gradually 
 given out to the plant. 
 
 These woollen rags are most extensively 
 used in Kent and Sussex, as a dressing for the 
 hop grounds, where they produce a very striking 
 effect. They have also been used on wheat 
 with very good results, but we should consider 
 them more adapted to beans and crops consist- 
 ing of carbonaceous matter, than w^heat. 
 
 Irrigation. — The last fertilizer we purpose 
 noticing, is not the least valuable in the effects 
 it produces. In the paragraph on Water fp. 
 69,) we have given its chemical formation and 
 the changes it undergoes. Here the only sub- 
 ject for our consideration, is the effects pro- 
 duced by artificial irrigation, and the causes 
 to which such effects are attributable. 
 
 It has been repeatedly tried to grow plants 
 in pure distilled water, free from any admix- 
 ture; but in every such case the plant has never 
 
152 IRRIGATION. 
 
 arrived at perfection : and the conclusion we 
 would draw from this is, that water owes its fer- 
 tilizing power as much to the foreign sub- 
 stances it contains, as to its moisture. 
 
 This being the case, we have only to reflect 
 on the large quantity of soluble matter every 
 river and every stream brings with it; almost 
 all of which is deposited in its transit over the 
 surface of an absorbent meadow, to be satisfied 
 that this is one of the principal sources of the 
 fertilizino^ effects of irrio^ation. 
 
 Much, however, depends upon the character 
 of the water, the sources from which it springs, 
 and the character of the soil through which it 
 passes, its local position in or near to large 
 towns, from which an incalculable supply of 
 matter is always obtained. 
 
 In speaking of the kind of water most ser- 
 viceable as a fertilizer, hard water is perhaps 
 to be preferred, because it owes this character 
 to the quantity of sulphate of lime (gypsum) it 
 contains in solution, and which being depo- 
 sited on the lands over which it passes, acts in 
 the same way as gypsum applied as a top 
 dressing. 
 
 Sir Humphrey Davy was of opinion, that the 
 temperature of water exerted a considerable 
 influence on the growth and development of 
 vegetation — and there is no doubt but that this 
 has its effect — but it is n'ow supposed to be sub- 
 ordinate in its effects to those produced by the 
 causes already stated, and by the oxidizement 
 of various matters contained in the soil; and 
 which being thus effected by the continual 
 
CONCLUSION. 153 
 
 passage of the water, are thereby rendered in a 
 fit state to act as the pabulum of the grass, by 
 furnishing an increased supply of carbon. 
 
 That the fertilizing effects of irrigation are 
 due to the presence of something more than 
 mere water, may be proved from the fact, that 
 stagnant water produces the very reverse of a 
 running stream, which is quite contrary to 
 what should be the case, was water the only 
 requisite for a luxuriant vegetation. 
 
 CONCLUSION. 
 
 We have thus completed the task originally 
 contemplated, we have traced the organization 
 of the vegetable structure and the functions al- 
 lotted to each part of the plant, from the period 
 of the germ's first appearance to the completion 
 of its allotted purpose— -the ripening of the 
 seed. 
 
 The subject of the composition of the goil 
 has also come under our notice, and we have 
 endeavoured to point out the conditions neces- 
 sary to be observed, for the perfection of the 
 crops growing on its surface; and, lastly, the 
 matter composing the structure of the plant 
 itself, the sources from which it is derived, and 
 the manner in which it is assimilated, have 
 been fully entered into, leaving, it is hoped, 
 little in the present state of our knowledge on 
 this subject to be desired. This with the spe- 
 cific action of the various manures, completes 
 the subject, which it is hoped will be found 
 practically useful to those employed in the cul- 
 tivation of the soil. 
 
154 CONCLUSION. 
 
 We know not that more cogent arguments 
 for the union of Chemistry with Agriculture 
 can be adduced, than already exist in the stimu- 
 lus all parties possess for advancing their indi- 
 vidual interests; but of this we may feel assu- 
 red, that as the end and object of all knowledge, 
 in connexion with this subject, is to increase 
 the produce of the earth, so those who will not 
 avail themselves of the assistance chemistry 
 affords, will be left behind in the struggle which 
 is going on; and farther, those who do rely on 
 science for an elucidation of the hitherto mys- 
 terious operations of nature, will not only derive 
 a direct and immediate benefit from the applica- 
 tion of chemistry to agriculture, but they will 
 also proceed with less difficulty, from being as- 
 sured that the laws of nature are uniform in 
 their operation, and that a certain cause will 
 always induce a certain result. 
 
 THE END. 
 
INDEX. 
 
 Absorption of Q^rbonic Acid 49 
 
 Ammonia 
 Acidity of Plants 
 Agriculture, its Importance 
 Ammonia, its Composition . 
 yielded by Volca- 
 noes 
 absorbed by Char, 
 coal 
 Analysis of Animal matter 
 Ammonia 
 Barley 
 Beans 
 Buckwheat 
 Bran 
 Bones 
 Chalk 
 
 113 
 
 74 
 
 8 
 
 55 
 
 66 
 
 119 
 
 60 
 
 113 
 
 77 
 
 28 
 
 28 
 
 77 
 
 105 
 
 100 
 
 115 
 
 77 
 
 132 
 
 39 
 
 77 
 
 136 
 
 91 
 
 106 
 
 40 
 
 28 
 
 84 
 
 Apatite 
 Ashes, ' 
 
 Fir tree . 
 Guano 
 Gum 
 
 Le.Tves of Oak . 
 Night Soil 
 Nitrate of Soda , 
 Nitrate of Lime 
 Oil . 
 Peas 
 Potash 
 Phosphate of 
 
 Lime . . 105 
 Soda . . 89 
 
 Salt ... 86 
 Sugar . .39 
 Starch . . 39 
 Urine . . 141 
 Woollen Rags . 151 
 Wheat . 139,59 
 WheatStraw,109,77 
 Water . . 69 
 . 105 
 
 f 
 
 Wood 
 Coal 
 Peat 
 Beech 
 
 114 
 115 
 116 
 115 
 
 Base of Plants ... 74 
 
 Beet Root . . . .10 
 
 Cultivation . . 73 
 
 Bird's Dung . . .127 
 
 Blubber . . . . 118 
 
 Bread . . . .93 
 
 Carbon . . . .36 
 
 Carbonate of Ammonia . 60 
 
 Carbonic Acid Gas . . 38 
 
 absorbed by Char- 
 coal . . 119 
 
 a constituent of 
 
 Plants . . 42 
 
 Chalk . . . .100 
 
 Charcoal . . . .119 
 
 Chemistry, its utility . . 6 
 
 Chlorine . . . .87 
 
 Coal Ashes . . .115 
 
 Compost Heap . . 82, 145 
 
 Danbeny on Ammonia . 66 
 
 Nitrate of Soda 92 
 
 Davy on Soils . . .25 
 
 Decay of matter . . 47 
 
 Dung . . . .122 
 
 Birds . . .127 
 
 Dogs . . .133 
 
 Efflorescence of Nitre . 79 
 
 Electricity . . . 22 
 
 Excess of Nutriment . . 48 
 
 Excrement of Plants . . 30 
 
 Animals . 66 
 
 Fallow Crops . 
 
 Farm. Yard Manure 
 
 Fat . 
 
 Fibres of Roots . 
 
 Fir, Norwegian 
 
 Fish . 
 
 Fish Oils . 
 
 Flint . 
 
 Flour 
 
 . 28 
 . 122 
 . 116 
 . 16 
 . 75 
 . 117 
 . 116 
 . 109 
 . 93 
 
156 
 
 INDEX. 
 
 Gas Liquor . . ' . 133 
 
 Lime .... 135 
 Gluten, its Analysis . . 58 
 of Wheat . .91 
 Guano .... 127 
 Gypsum .... 102 
 
 Heat, its effects . . .122 
 
 Henry on Nitrates . . 90 
 
 Humic Acid , . ,85 
 
 Humus . . . .40 
 
 Hydrogen . . .79 
 
 Influence of the Food 
 
 . 126 
 
 Irrigation . 
 
 . 151 
 
 Juices of Trees contain 
 
 
 Ammonia . 
 
 . 62 
 
 Kemp on the use of Salt 
 
 . 88 
 
 Lava 
 
 . 27 
 
 Leaves of Plants 
 
 . 18 
 
 Light . . . 
 
 19, 73 
 
 Lime 
 
 . 99 
 
 Sulphate . 
 
 . 102 
 
 Limestone Magnesian 
 
 . 108 
 
 Liquid Manure . 
 
 135, 63 
 
 Lucerne 
 
 . 30 
 
 Magnesia .... 107 
 Manufacture of Saltpetre . 81 
 Manures . . . .112 
 Moisture . . . .21 
 
 Night Soil . . . .136 
 
 Nitrate of Lime . 106,83 
 
 Soda . . 90 
 
 Nitrogen . . . .56 
 
 Oils 116 
 
 Oxygen . . .44, 72 
 
 Peat Ashes . . .116 
 
 Phosphate of Lime . . 99 
 
 Magnesia . 107 
 
 Phosphorus . . .98 
 
 Plants, Structure of . .14 
 
 absorb Carbon . . 46 
 
 purify the air . . 54 
 
 Potash . . . .79 
 
 Process of Asshnilation . 71 
 
 Rain 61 
 
 Rock Salt . . . .87 
 Roots of Plants ... 16 
 Rotation of Crops . , 28 
 
 Salt 86 
 
 Saltpetre . . . 10, 80 
 Seeds . . . .20 
 
 Silex . . . .109 
 
 Soda . . . .85 
 
 Soil . . .26, 138 
 
 Spongelets of the Roots . 16 
 Starch .... 65 
 Stem of Plants ... 17 
 Sugar made in France . 9 
 Sulphate of Ammonia . 103 
 
 Sulphuric Acid . . 143 
 
 Teeth, Composition of . 78 
 
 Volcanoes yield Ammonia . 66 
 
 Urine . . . .139 
 
 Wheat manured with 139 
 
 Water 
 
 its uses 
 Wheat 
 
 Straw 
 Wood Ashes 
 Woollen Rags 
 
 139, 
 
 36 
 69 
 59 
 
 . 77 
 
 83,114 
 
 . 151 
 
i- 
 
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