Qass. 
 Book. 
 
/ 
 
 -- '' 
 
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 u 
 
 PRODUCTIVE FARMING 
 
 V 
 
 A FAMILIAR DIGEST OF THE RECENT DISCOVERIES OF LIEBIG, 
 JOHNSTON, DAVY, AND OTHER CELEBRATED WRITERS ON 
 / VEGETABLE CHEMISTRY; SHOWING HOW THE RESULTS 
 OF TILLAGE MIGHT BE GREATLY AUGMENTED. 
 
 BY JOSEPH A. S: 
 
 NEW Y|5wK: ^ 
 ON & C^^^^OO BRO 
 
 D. APPLETON & C^TT^OO BROADWAY 
 PHILADELPHIA: 
 
 GEO. S, APPLETON, 148 CHESNUT STREET. 
 1843. 
 
 L . I'. 
 

 
 JOHN F. TROW, PRIISTER, 
 33 Ann-street, 
 
 5- 
 
 By Traiisfor ^ 
 
 Dept. of Agrtctdttire ^ 
 
 OCT 1? 1840 Y. 
 
PRODUCTIVE FARMING 
 
CONTENTS 
 
 CHAPTER I. 
 
 Page 
 Introductory Observations, 9 
 
 CHAPTER n. 
 
 Some Account of the Simple or Elementary Bodies found 
 
 (combined or uncombined) in Animals, Plants, and Soils, - 23 
 
 CHAPTER ni. 
 
 Plants and Animals are both alike endowed with Life ; the 
 
 Elementary Materials and many of the Proximate Principles • 
 
 of Animal and Vegetable matter are precisely identical — 
 they have similar Organs essential to their growth and re- 
 production, and are nourished or destroyed by the same 
 agencies, 33 
 
 CHAPTER IV. 
 
 Of the Elementary Composition of Water ; of the Composi- 
 tion of the Atmosphere; and of the artificial Application of 
 Water to Grass Lands, 55 
 
 CHAPTER V. 
 
 Of the Nature of Vegetable Growth ; the true use of Vege- 
 table Mould or Humus; and of the Sources of the Element- 
 ary Constituents of Plants, 60 
 
 CHAPTER VI. 
 
 Of the Sources of the Saline, Earthy, and other Unorganized 
 
 Constituents of Vegetables, 81 
 
 CHAPTER VII. 
 
 Of the necessary Relation between the Composition of a Soil 
 and the Vegetables it is fitted to raise. Fallowing and 
 Green Crops considered as Vegetable Manure, - - - 86 
 
CONTENTS. 
 
 CHAPTER VIII. 
 
 Of the Nature and correct Use of the Excrements of Animals 
 considered as Manure ; the Mode of its Action and Preser- 
 vation. — Bone Dust, and dead Animal Matter, - - - 97 
 
 CHAPTER IX. 
 
 Of the comparative Value of Vegetable Manure, as contrasted 
 
 with Animal Excrements, ------- 116 
 
 CHAPTER X. 
 
 Of Manures of Mineral Origin, or Fossil and Artificial or 
 Chemical Manures ; their Preparation, and the Manner in 
 which they act. — Of Lime in its dift'erent States ; its Opera- 
 tion as a Manure. — Of Alkalies and Common Salt, as to 
 their Action upon the Land, ----- . 119 
 
 CHAPTER XI. 
 
 jOf the Composition of Productive Soils, and of the Agency 
 of the Elements in their Natural Formation from the Rocks 
 upon which they rest, • 129 
 
 CHAPTER XII. 
 
 Of the Chemical Analysis of Soils, and how far this is practi- 
 cable by tlie Farmer, 143 
 
 CHAPTER XIII. 
 Of Advertised " Fertilizers" for the Soil, - . • - 148 
 
PREFACE. 
 
 This book is a compilation. The object of its com- 
 piler has been the simplification of the more strictly- 
 scientific and technical writings of the principal agricul- 
 tural writers of the present age. Practical farmers 
 require the simplest and most elementary statements. 
 The position of the agricultural interest renders it de- 
 sirable that the recent views of Professor Liebig, the 
 distinguished chemist, who has effected a complete revo- 
 lution in the physiology of vegetation, should be pre- 
 sented in a style free from difficulty, condensed and 
 separated from such portions of his work as would only 
 bewilder ordinary readers. How far the attempt may 
 be successful, the world must judge. The published lec- 
 tures of the late Sir Humphrey Davy have been freely 
 cited, and such portions selected, as, while they do not 
 clash with later discovery, may prove a useful addition. 
 The writings of Mr. Johnston, whose little elementary 
 book is well known, have been laid under contribution, 
 as well as the lectures of Dr. Mason Good ; and such 
 useful statements as have appeared at various periods in 
 periodicals devoted to the furtherance of agricultural 
 science. It is to be hoped, that without torturing the 
 sense of previous writers, nothing will be found in these 
 
b PREFACE. 
 
 pages inconsistent with the doctrines of the learned Ger- 
 man professor, whose writings, though admirably adapted 
 for the perusal of those who are familiar with chemistry 
 and physiology, are susceptible of being abridged and pre- 
 sented to the industrious farmer in a form less repulsive, 
 because less learned, and consequently, more generally 
 intelligible. 
 
MODERN AGEICULTUUE 
 
 CHAPTER I. 
 
 Introductory Observations. 
 
 Agricultural Science has for its objects all those 
 changes in the arrangements of matter connected with the 
 growth and nourishment of plants, the constitution of soils, 
 the manner in which lands are enriched by manure, or ren- 
 dered fertile by the different processes of cultivation; and 
 no rational system of farming can be formed without the 
 practical application of well-understood scientific princi- 
 ples. Such a system must be based on an exact acquaint- 
 ance with the means of nutrition in vegetables, with the 
 influence of soils, and the action of fertilizing materials 
 upon them. The object of the farmer is, to raise from a 
 given extent of land the largest quantity of the most valu- 
 able produce at the least cost, with the least permanent 
 injury to the soil ; and the sciences of chemistry and geology 
 throw light on every step he takes, or ought to take, in 
 order to effect this main object. Whoever reasons upon 
 agriculture is obliged continually to recur to these sciences. 
 He feels that, without such knowledge, it is scarcely pos- 
 sible to advance one step ; and, if he be satisfied with 
 insufficient views, it is not because he prefers them to accu- 
 rate knowledge, but generally because they are more cur- 
 rent. It has been said, and undoubtedly with great truth, 
 that a philosopher would most probably make a very un- 
 profitable business of farming ; and this, certainly, would 
 be the case if he were a mere philosopher. But there is 
 2 
 
10 PRODUCTIVE FARMING. 
 
 good reason to believe, that he would be a more successful 
 aj^riculturist than a person equally ignorant of farming, but 
 ignorant of chemistry altogether: his science, as far as it 
 "Went, would be useful to him. The great purpose of 
 chemical investigation in agriculture ought, undoubtedly, 
 to be the discovery of improved methods of cultivation ; 
 but to this end, not only practical knowledge but general 
 scientific principles are alike necessary; nor is industry 
 ever so efficacious as when directed by science ; as he 
 who, journeying in the night, aided by the most intelligible 
 directions as to the way, is more certain of his footsteps if 
 he carry a lamp to explore his path. Science cannot long 
 be despised by any persons as the mere speculation of 
 theorists, but must soon be considered, by all ranks of men, 
 in its true point of view, — as the refinement of common 
 sense, guided by experience, gradually substituting sound 
 and rational principles for vague popular prejudices. If 
 land be comparatively unproductive, the sure method of 
 determining the cause is, first to ascertain the exact nature 
 and relative quantities of the ingredients which form the 
 soil, (which can only be done by chemical analysis,) and 
 then to supply such soil with the deficient materials requi- 
 site for the growth of such vegetables as it is best fitted to 
 raise. The preparation of compost will only be of real 
 use when materials, which do not afiford singly an efficient 
 or convenient manure, are made to do so by their mixture. 
 Every farmer has it in his power so to compound the best 
 from his store of manuring materials, that the defects of 
 his soil may not only be remedied, but that the crops may 
 receive those substances in sufficient quantity which are 
 required for their vigorous growth. To do this, however, 
 it is requisite to know not only the component parts of the 
 soil, but also those of the crops. If these are not taken 
 into account, no clear idea either of the composition, much 
 less of the action of manure, will ever be obtained ; and 
 many substances of real value will be tried, and, from mis- 
 application, tend to useless, if not injurious results. Per- 
 haps iron may be found in injurious excess, which may be 
 
PRODUCTIVE FARMING. 11 
 
 rendered harmless by the addition of lime ; or an excess 
 of sand may be neutralized by the addition of clay. Is 
 there a deficiency of lime 7 The remedy is obvious ; or an 
 excess of undecomposed vegetable matter may be removed 
 by the judicious use of lime, by paring and burning. With 
 the aid of chemistry, the precise value of any variety of 
 limestone may be determined in a few minutes ; and so its 
 fitness or unfitness, as one among many substances intended 
 to fertilize the soil, may be determined by a less expensive 
 experiment than waiting to observe its action upon the 
 land. In the same way, peat earth of a certain consistence 
 and composition is an excellent manure; but there are 
 some varieties of peat which contain so large a quantity of 
 iron as to be absolutely injurious, if not destructive to corn 
 and grasses. Now, nothing can be more necessary, more 
 useful, and fortunately more simple, than the mode of de- 
 termining whether a metallic substance be present. More 
 especially, it is solely by a reference to the elementary 
 principles of chemistry, and the ascertained constitution of 
 manures, vegetables, and the air and soil in which they 
 live and thrive, that we can determine whether it is wiser 
 to plough that manure into the land, to apply it in a fresh, 
 or in a fermented and decomposing state. We know, 
 that soon as dung begins to decompose, it throws off its 
 volatile or gaseous parts. It is necessary that what is thus 
 lost should be examined. It may be (which is the fact) 
 that such evaporation is not only the escape, but the actual 
 loss of that which forms a most material ingredient in the 
 food of plants : and so, whether this shall be supplied 
 gradually to the growing vegetable, or suddenly, is a tan- 
 tamount question in the mind of an intelligent agriculturist 
 to the inquiry often agitated among practical farmers, and 
 determined only by individual caprice or fancy, as to 
 whether the produce of the stable or the farm-yard is best, 
 when spread upon the soil in a fresh or in a putrid state. 
 When, for instance, it is considered, that with every pound 
 of the strongly-pungent smelling ammonia lost in the air, 
 a loss of at least sixty pounds of corn must correspondingly 
 
12 PRODUCTIVE FARMING. 
 
 be sustained, — and that with every pound of urine a pound 
 of wheat might be produced, — not only must we feel sur- 
 prise at the ignorance which prevails as to the fact, but 
 equally so at the indifference manifested by those who are 
 aware of the value of such manure as to the best mode of 
 applying it. On some soils a plant will thrive, on others 
 it will sicken ; and the same knowledge which will enable 
 us to correct a faulty or weak vegetation, will enable us also 
 to produce far more abundant results than occur under the 
 most favourable ordinary and natural circumstances. Agri- 
 culture has hitherto never fairly sought aid from that sci- 
 ence which is based on the knowledge of those substances 
 which plants extract from the soil, and of those restored 
 to the soil on which they grow by means of manure. The 
 application of such principles will be the task of a future 
 generation ; for what can be expected from the present, 
 which recoils with seeming distrust and aversion from all 
 the means of assistance offiered by chemical investigation ? 
 A future generation will derive incalculable advantage from 
 these means of help, and make a rational use of philosoph- 
 ical discoveries. Here a marked and wide difference ex- 
 ists between the progress of manufacture and the history 
 of agricultural operations. We see the steam-engine mul- 
 tiply indefinitely the labour of the human hand — supersede 
 and almost infinitely exceed the united power of brute 
 exertion; invention has lacked no mechanism to produce 
 myriads upon myriads of the same fabric ; thousands of 
 piles of manufactured silks and cottons are produced annu- 
 ally, one factory supplying daily as many yards as would 
 encircle the globe — strange advancement on the ancient 
 spinning-wheel ; while the sons of the soil still toil on 
 through the long summer months, and brave the winter's 
 cold, to reap the same quantity of produce from the soil as 
 their forefathers of a thousand years ago. We do not say 
 that there is no limit to the capabilities of the earth's sur- 
 face, but fearlessly maintain that such limit is yet far from 
 realization ; and that not until prejudice be silent, and in- 
 teUigence more universal, can it be hoped that the broad 
 
PRODUCTIVE FARMING. 13 
 
 acres of our island home will yield to science and skill all 
 the treasures they contain. 
 
 At a recent meeting of one of the Irish agricultural 
 associations, a Scottish agriculturist is reported to have 
 said, among other things, that " If science were permitted 
 to do for farming all of which science is capable, the cla- 
 mour about repeal of the Corn Laws would soon cease, 
 and the prospect of starvation before us would vanish." 
 He observed, that " Great Britain, besides supplying her 
 own population with food in abundance, would become an 
 exporting country for ages to come : that unless a more 
 rational system of farming be adopted throughout the 
 country, we shall have want, and its offspring, crime, at 
 our doors and on every side of us. The manufacturers 
 are offering premiums on the increase of population. That 
 population is increasing far beyond the supply of food ne- 
 cessary for it, [he might have added, at the rate of a 
 thousand a day, while the surface of our island remains the 
 same ;] and unless the government, or the great agricultu- 
 ral societies, take the matter in hand, and that speedily, we 
 shall soon feel that, solely from lack of food for her manu- 
 facturing population, the greatness of this empire, so long 
 the wonder and envy of the world, will become a thing to 
 be talked of as a tale that has passed away." 
 
 Haifa century sufficed to Europeans, not only to equal, 
 but to surpass the Chinese in the arts and manufactures; 
 and this was owing merely to the application of correct 
 principles deduced from the study of chemistry. But how 
 infinitely inferior is the agriculture of Europe, even of 
 boasted England, to that of China! The Chinese are the 
 most admirable gardeners and trainers of plants, for each of 
 which they understand how to prepare and apply the best 
 adapted manure. Their agriculture is the most perfect in 
 the world : and there, where the climate in the most fertile 
 districts differs little from the European, very little value 
 is attached to the excrements of animals. Patient obser- 
 vation of results, and a ready adoption of really useful 
 plans ; steady persistence, not in antiquated methods and 
 
14 PRODUCTIVE FARMING. 
 
 notions, but in all that has been found by experience to be 
 beneficial, — has raised the agriculture of that country, long 
 ago, to a position which would rapidly, nay, instantly, be 
 ours, if science were permitted to achieve for us that 
 which, with them, has been the slow growth of centuries of 
 experiment. 
 
 The soil of England offers inexhaustible resources, 
 which, when properly appreciated and employed, must 
 increase our wealth, our population, and our physical 
 strength. The same energy of character, the same ex- 
 tent of resources which have always distinguished Eng- 
 lishmen, and made them excel in arms, commerce and 
 learning, only require to be strongly directed to agriculture, 
 to ensure the happiest effects. We possess advantages in 
 the use of machinery and the division of labour, peculiar 
 to ourselves ; and these having been mainly instrumental in 
 aiding one great division of human industry, we are justi- 
 fied in the assertion, that the steam-engine and machinery 
 has not done more for trade, than science and skill, in 
 various ways, may do for land. Although it is obvious to 
 all reflecting persons, that machinery, which is science in 
 another form, is a good thing, we cannot wonder if we find 
 some ready to say, " I know it is a bad thing, for it de- 
 prived me of employment." To attempt to convince such 
 a man would be difficult. It would be useless to argue 
 with that man, that a number of individuals had gained, 
 though he was a loser. His loss is to him evident ; and 
 the gain spread over a vast surface of society is an argu- 
 ment which makes no impression upon him. 
 
 Besides chemistry, there is another science which has 
 many relations to practical farming — the science of geolo- 
 gy, or that which embodies all ascertained facts in regard 
 to the nature and internal structure, both physical and 
 chemical, of the solid surface of our globe. Though the 
 substances of which soils chiefly consist are so few in number, 
 yet every practical man knows how very diversified they are 
 in character, how very different in value. Thus, in some 
 of the southern Enghsh counties we have a white soil, con- 
 
PRODUCTIVE FARMING. 15 
 
 sisting, apparently, of little more than chalk ; in the cen- 
 tral part of the country, a wide plain of dark-red land ; in 
 the border counties of Wales, and on many of our coal fields, 
 tracts of country almost perfectly black; while yellow, 
 white and brown lands give the prevailing character to the 
 soils of other districts. These differences arise from the 
 varying proportions in w^hich the sand, lime, clay, and iron 
 which colour the soils have been mixed together. Now, 
 geology explains the cause why they have been so mixed 
 in different parts of the country — by what natural agency, 
 and for what end ; and by its aid we can predict the gene- 
 ral quality of the surface-soil, and, more than this, of the 
 unseen sub-soil in the several parts of entire kingdoms. 
 We may learn, if the soil be of inferior quality, and yet 
 susceptible of improvement, whether the means of improv- 
 ing it are likely, in any given locality, to be attainable at 
 a reasonable cost. 
 
 Whether we attempt to investigate the composition of 
 natural bodies, or, confining our attention to the review of 
 those general diversities so remarkable on the earth's sur- 
 face, the division of them all into two grand classes, as 
 simple or compound, is an essential preliminary to a cor- 
 rect comprehension of the subject. Those substances are 
 simple, which cannot, by any known method, be separated, 
 decomposed, or divided, in such a manner as to produce 
 particles different in their properties from one another. On 
 the other hand, those substances are compound which, by 
 experiment, maybe resolved into particles of an unlike na- 
 ture. Thus, marble is a compound body ; for by a strong 
 heat it is converted into lime— an elastic fluid, which is 
 carbonic acid gas, (itself also a compound,) being disen- 
 gaged during the process. Vegetable substances, whether 
 in their living or dead state, are mostly of a very compound 
 nature, and consist of a great number of elements. For a 
 period of many centuries, and even till a very late date, 
 there were four substances held to be elementary, or sim- 
 ple. These were Fire, Air, Earth, and Water. Nobody 
 could prove them so ; and yet, of these four bodies, all 
 
16 PRODUCTIVE FARMING. 
 
 others in nature were supposed to be constituted. This 
 system continued to be orthodox till very lately, when three 
 of these imaginary elements, namely, Air, Water, and 
 Earth, were proved to be compounds ; and, as we shall see 
 in the progress of this work, a correct understanding of the 
 properties of the atmosphere, and of its relative agency over 
 vegetation, is indispensable to the adoption of such plans 
 as are intended to increase the fertility of the soil. As to 
 fire, it is still unknown whether it be simple or compound, 
 in what its essence consists, or by what causes its effects 
 are produced. The study of temperature, of the relative 
 dryness or moisture of the air, of the action of the sun's 
 hewt over soils and vegetation, is closely identified with the 
 science of agriculture. The influence of the changes of 
 seasons and of the position of the sun on the phenomena of 
 vegetation, demonstrates the effects of heat on the functions 
 of plants. The matter absorbed from the soil can only 
 enter the roots in a fluid state ; and when the surface is 
 frozen, this mode of communication is suspended. The ac- 
 tivity of chemical changes in living vegetables is likewise 
 increased by a certain increase of temperature, as is evident 
 if a stalk of henbane be partially immersed in hot water : 
 its leaves will, for a time, become erect, and quickly forego 
 their drooping arrangement, evidently referable to the in- 
 creased rapidity with which fluids, under such circum- 
 stances, rise in the minute vessels of the vegetable. Heat, 
 then, is rather to be regarded as an agency by which both 
 compound and simple substances are alike affected. What 
 the ancients considered to be simple bodies, are no longer 
 considered to be such : but, in place of these four assumed 
 substances, the chemists of modern times have elevated to 
 the dignity of elements, or simple bodies, a far more nume- 
 rous race. No one, however, asserts now-a-days, that even 
 these are all absolutely simple. The term " element," in- 
 timates no more than that the body to which it is applied 
 has never, in the opinion of modern chemists, been subject 
 to further d vision or decomposition : that it has never been 
 divided into particles, different from one another, or from 
 
PRODUCTIVE FARMING. 17 
 
 the original substance. The number of simple, or elemen- 
 tary substances, at present known, and constituting visible 
 Nature around us, xs fifty-four. 
 
 Now, if these elementary, or simple substances are 
 placed either artificially, or, as they are presented in the 
 universe, naturally in contact with each other, they com- 
 bine, or refuse to combine ; and by such combination, when 
 it occurs, a great variety of compound substances are pro- 
 duced. Some combinations are effected instantly, some 
 more slowly and with difficulty, and there are certain ele- 
 ments which can scarcely, by any means, be made to com- 
 bine. The compounds produced by such combinations 
 possess properties very different from those of the sepa- 
 rate elements of which they are composed. Thus, carbonic 
 acid, or the gas which sparkles in fermented liquors, com- 
 bines very readily with pure caustic lime, and the product 
 of the union is common chalk. So, if the proportions be 
 varied, the same two elements produce the common air we 
 breathe and the strongest aquafortis or nitric acid. The 
 power, in virtue of which simple bodies can combine and 
 produce compounds, is one of which the nature is totally 
 unknown. Chemists have learned no more than that sim- 
 ple bodies, or bodies supposed to be simple, do combine ; 
 but WHY they combine, or W'hat that is which makes them 
 combine, they have not discovered. To the illustrious 
 Dalton belongs the discovery that they do not unite at 
 random, but always in definite proportions of each; so 
 that, if the elements be represented by numbers, the pro- 
 portions in which they unite may be expressed either by 
 those numbers, or by some simple multiples of them. Thus, 
 sugar and Indian rubber are compounds resolvable into 
 precisely the same ultimate elements, only in different pro- 
 portions ; and, as the following table will illustrate, nearly 
 one half the weight of all vegetable productions which are 
 gathered for food for man or beast, in their dry state, are 
 but varying compounds of the same elementary or simple 
 bodies, the names of which are appended over the an- 
 nexed numbers. What the properties of these elements 
 
18 PRODUCTIVE FARMING. 
 
 in their separate state may be, is not our immediate pur- 
 pose. 
 
 Carbon. Hydrogen. Oxygen Nitrogen. Ash. 
 
 Hay, .... 458 50 387 15 90 
 
 Potatoes, . . 441 58 439 12 50 
 
 Wheat straw, 485 52 389 4 70 
 
 Oats, .... 507 64 367 22 40 
 
 parts by weight in 1000 pounds of each of the above veg- 
 etable substances. 
 
 If we take the ash left by a known w^eight of wheat 
 straw, or of hay, and mix it with the proper quantities of 
 the four elementary substances named in the foregoing ta- 
 ble, we shall certainly be unable, by this process, to lorm 
 either the one or the other. The elements, therefore, into 
 which all vegetable compounds are ultimately resolvable, 
 are not merely mixed together; they are united in some 
 closer and more intimate manner. To this more intimate 
 state of union the term chemical combination is correctly 
 applied. Again, woody fibre, gum, sap, and the various 
 fluids and substances which form a plant, are themselves 
 mostly resolvable into varying proportions of the same ulti- 
 mate elements, which, taken together form the entire vege- 
 table. Thus, sugar forms one of the proximate principles 
 of the sugar cane, and India rubber is one of the proxi- 
 mate principles of a South American tree, which contains 
 no sugar ; yet sugar and India rubber are essentially com- 
 posed of the same materials. So, if charcoal be burned in 
 the open air, it slowly disappears, and forms a kind of air 
 or gas, known by the name of carbonic acid, an elastic 
 fluid precisely identical with that which forms the froth in 
 ginger beer or common yeast. Now^, this carbonic acid is 
 formed by the union of the charcoal or carbon, while burn- 
 ing, with one of the elements composing common air, 
 named oxygen; and in this new form, the elements carbon 
 and oxygen are said to be chemically combined. Again, 
 if certain vegetable and animal materials are mixed to- 
 gether, and left to the agency of the atmosphere, they re- 
 
PRODUCTIVE FARMING. 19 
 
 act upon each other — perhaps become heated, as happens 
 in a heap of stable dung, and are said to become decomposed. 
 New compounds are formed from the union of previously 
 existing elements; perhaps ammonia is one of the most com- 
 mon and obvious, as indicated by its effect upon our eyes 
 and nostrils. This, then, is as purely a chemical process as 
 the conversion of wood into vinegar, or into charcoal, or 
 the change that occurs when the flour of grain is convert- 
 ed by the distiller into ardent spirits ; and in all well-direct- 
 ed attempts to fertilize the soil, a knowledge of these 
 changes is absolutely necessary : at least, he who proceeds 
 without it has disappointment in prospect, and gropes in 
 the dark, with uncertainty for his guide. 
 
 Now, chemical affinity is not only evident in the changes 
 which masses of dead inorganic matter produce upon each 
 other: it is found to be actively at work in the phenomena 
 of vegetation ; thus proving that the growth of plants is 
 more completely a chemical process than might have been 
 imagined : and, as our further illustrations will tend to 
 prove, the same law of affinity is equally operative upon 
 animal structure, which, like that of plants, is not more 
 truly alive than they. The sap consists of a number of in- 
 gredients dissolved in water by chemical attraction ; and 
 it appears to be in consequence of the operation of this 
 power, that certain principles derived from the sap are 
 united to the vegetable organs. By the laws of chemical 
 attraction, different products of vegetation are changed and 
 formed during the process of growth : vegetable and ani- 
 mal remains are decomposed by the action of air and water 
 or exert upon those fluids a mutual agency essential to the 
 change ; rocks are broken down and converted into soils, 
 and soils are more finely divided and fitted as receptacles 
 for the roots of plants. The repulsive energy of solar heat 
 or of that generated during chemical changes of constant 
 occurrence, serves as the only counterbalance to that at' 
 traction which pervades the particles of all living or dead 
 matter : and thus the harmonious circle of growth and de- 
 cay is produced by their mutual operations. The difl^erent 
 
20 PRODUCTIVE FARMING. 
 
 influence of the different solar rays on vegetation is but 
 partially understood. There are rays transmitted from ihe 
 sun which do not impart light, and which yet produce more 
 heat than the visible rays. The effect of these invisible rays 
 is purely chemical and independent of the heat they pro- 
 duce. Thus, potatoes, which sprout in a comparatively 
 dark cellar, send out nearly colourless shoots. Plants kept 
 in the dark in a hot-house, grow luxuriantly, but never 
 acquire their natural colours ; their leaves are white or 
 pale, and their juices watery and sweet. So the upper 
 surface of most leaves is darker than the lower, upon the 
 same principle that the belly of a fish is whiter than its 
 back. 
 
 The most obvious instance of Electrical Agency in ex- 
 ternal nature occurs in thunder and lightning. Electrical 
 changes are of constant occurrence ; but as yet the effects 
 of this power, not as accidental, but as essential to healthy 
 vegetation, have not been correctly estimated. No doubt 
 the germination of seeds, as well as the growth of plants, 
 is materially modified by the peculiar electrical condition 
 of the earth and the atmosphere, and by the varying state 
 of each. It is known that corn will sprout more rapidly 
 and readily in water positively electrified — that is, charged 
 with electricity in excess or beyond its natural quantity ; 
 and that if, by artificial means, water be deprived of its 
 natural amount of electricity, its power of stimulating the 
 growth of seeds is thereby diminished. Experiments made 
 upon the atmosphere show that clouds are usually deficient 
 of electricity ; and as when a cloud is in one state of elec- 
 tricity, the surface of the earth beneath that cloud is 
 brought into the opposite state, it is probable that, in com- 
 mon cases, the surface of the earth is charged with the 
 electric fluid in excess. 
 
 We have spoken of Chemical affinity : it is sometimes 
 well named Elective or Chemical attraction, in as much as 
 it is but an exemplification of one form of that law which 
 maintains the order of the universe. It is the expression of 
 the fact, that certain elements of unlike nature combine 
 
PRODUCTIVE FARMING. 21 
 
 with each other when placed in contact, or (figuratively 
 speaking) refuse to combine with any other, electing even 
 the proportions in which only such combinations can occur. 
 This affinity is but one division of the great law of attraC' 
 Hon. In this aspect, there are Jive forms in which the re- 
 lations of all bodies to each other may be arranged. We 
 begin with that which compels the heavenly bodies to 
 rotate round the sun ; or a stone when thrown upwards to 
 fall to the ground — in other words, to gravitate towards 
 the earth's centre. Next, there is the attraction of cohe- 
 sion : thus, particles of oil will rise through water, and 
 having reached the ransje of each other's attraction, will 
 unite into one common and separate body. It is this form 
 of attraction which gives roundness to the drops of dew, or 
 of the rain as it falls, and is the sole cause of the arched 
 form of the rainbow. In the same way, drops of water or 
 of quicksilver placed upon a dry plate, have a tendency to 
 unite, not only when they touch, but to run together when 
 placed near each other. So, perfectly smooth and polished 
 plates of glass or metal have a strong tendency to cohere. 
 It is by the same means that the great number of rocks 
 seem to be produced that enter into the substance of the 
 earth's solid crust. The lowermost rocks are united by an 
 intimate crystallization which is the most perfect form of 
 cohesive or aggregate attraction that can exist among the 
 particles of solid bodies. The next form of attraction is 
 observed as occurring between bodies unlike in their na- 
 ture, solids and fluids, capillary attraction, as when sap 
 rises in the minute vessels forming the stem of a tree against 
 its own weight, or in other language, overcoming the at- 
 traction of gravitation downwards. The Latin word which 
 signifies a hair, is used in this instance to form the word 
 denoting the extreme tenuity and delicacy of these narrow 
 vessels, as only in such could fluids rise : hence the reason 
 and the wisdom of this arrangement. 
 
 Electrical and Magnetic attraction are important sub- 
 jects for study, to which in a practical work it is not neces- 
 sary very minutely to allude. It is well ascertained that 
 
22 
 
 PRODUCTIVE FARMING. 
 
 the thorns, spines, or prickles that exist on a variety of 
 plants serve not merely for their defence ; they have a re- 
 lation to the electrical condition of the atmosphere ; cases 
 having been recorded in which spines have grown more 
 than an inch during a thunder-storm. Some of the acacia 
 tribe are fretted over with formidable spines which will 
 take off a charge of electricity from a prime conductor as 
 rapidly as a brass point— doubtlessly from the presence of 
 a metal in those spines, probably the metallic base of flint. 
 Now it is very unlikely that only the prickly plants require 
 the electric stimulus. We know that, though the torpedo 
 and electrical eel have power to benumb and kill, yet hu- 
 man beings, who have no such powers in health and in 
 disease, are always charged with varying quantities of the 
 electric fluid. So also of all vegetables : oat and wheat 
 straw contain silica, which is metallic ; and the firmness 
 of the stem may not be, and is not, the only reason for its 
 presence. Lastly, we have Chemical attraction or affinity. 
 A few instances of its operation have been already noted ; 
 but some affinities are more powerful than others. Pure 
 lime has a strong affinity for carbonic acid gas, and this is 
 a wise ordination ; and it is equally a proof of design that 
 it should form one of the ingredients of the atmosphere. 
 Under this arrangement of things, whole mountains of lime 
 have been crumbled during successive ages into fertile beds 
 of chalk. But lime has a still greater affinity for sulphmic 
 acid or oil of vitriol than it has for carbonic acid ; and so, 
 if natural or artificial chalk be subjected to the action of 
 vitriol, another decomposition ensues : the carbonic acid 
 flies off, leaving the lime to combine with the acid for 
 which it has a more powerful aflSnity, the result of the new 
 union being sulphate of lime, better known as alabaster or 
 common gypsum. These transformations may not only be 
 produced artificially, but are of constant occurrence, though 
 of slow operation, in the great laboratory of Nature. To 
 understand them is essential to the slightest knowledge of 
 those chemical changes w^hich are identical with the pro- 
 cesses of growth in the vegetable world, and indeed in all 
 
PRODUCTIVE FARMING. 23 
 
 living organized bodies,— and there are sufficient motives 
 connected both with pleasure and profit to er^ourage inge- 
 nious men to pursue this new path of investigation. 
 
 CHAPTER II 
 
 Some Account of the Simple or Elementary Bodies found (combined 
 or uncombined) in Animals, Plants, and Soils. 
 
 It is absolutely necessary, in order to a right appre- 
 hension of the changes that occur during vegetable growth, 
 and, of course, to a correct estimation of the most rational 
 methods of forcing or favouring healthy vegetation, that 
 we should become familiar with some of the most common 
 properties of those simple bodies or elements, of which all 
 nature around us is compounded. 
 
 Four of them, by combining with other simple bodies 
 that will burn, form acids ; eight of them are inflammable; 
 and there are upwards of forty metals. 
 
 First, let us speak of Oxygen. Oxygen, in union with 
 latent heat, forms Oxygen gas, constituting about one-fifth 
 of the air of our atmosphere. It is an elastic fluid at all 
 known temperatures. It is heavier than the air, and sup- 
 ports combustion with much more vividness than common 
 air ; so that if a small steel wire, or a watch spring, having 
 a bit of burning wood attached to it, — or, better still, a 
 bit of phosphorus or brimstone, be introduced into a bottle 
 filled with this gas, it burns with surprising splendour. 
 Oxygen is a substance very extensively diflfused throughout 
 the material world: it forms with nitrogen the air we 
 breathe; united with another element, named hydrogen, it 
 forms water. It exists as a constituent of all animal and 
 vegetable matter; and is found also naturally in combina- 
 
24 PRODUCTIVE FARMING. 
 
 tion with most mineral productions; from some of which, 
 for experimental purposes, it may with great ease be pre- 
 pared. Oxygen gas, when suddenly compressed, evolves 
 both light and heat ; is sparingly dissolved by water, 100 
 cubic inches taking up only three or four of the gas. If a 
 mouse, or a bird, were confined under a large bell-glass, 
 filled with common air, it would live until it had consumed all 
 the oxygen contained in that portion of air, and no longer. 
 If, instead of the bird, a bit of burning brimstone, or a can- 
 dle were placed there, it would burn until it had absorbed 
 all the oxygen, and then become extinguished. 
 
 2i Hydrogen. — Hydrogen, or inflammable air, is the 
 lightest known substance, being about sixteen times lighter 
 than common air. For this reason, it is used in filling 
 balloons. The common gas in the streets and shops 
 is mostly used for this purpose, instead of pure hydrogen ; 
 the carbon it contains not materially destroying its light- 
 ness. Not only is pure hydrogen the lightest of gases, 
 but it is highly inflammable ; it W'ill neither support com- 
 bustion nor respiration ; in other words, if a lighted taper 
 or a living animal be immersed in pure hydrogen gas, it 
 would cease to burn, or die. Hydrogen and oxygen are 
 the two elements w'hich form pure water, of which we must 
 say more in another place. When these gases are mixed 
 in certain proportions, they unite and explode with great 
 violence if a lighted candle be brought in contact with 
 them ; for experiment' sake, one part of hydrogen, and six 
 of oxygen or even atmospheric air, w^ill form a very power- 
 ful explosive mixture. When a stream of hydrogen gas 
 issuing from one vessel, and a jet of oxygen from another, 
 are made to inflame as they unite, a most intense heat will 
 be generated, sufficient to melt the clay of a common to- 
 bacco pipe, and render lime perfectly fluid. Neither hy- 
 drogen nor oxygen are known to occur anywHerein nature 
 in any sensible separate quantity. They are abundant 
 enough in combination with other matters. 
 
 3. JYitrogen, sometimes called Azote, is another ele- 
 mentary substance, entering most largely into the constitu- 
 
PRODUCTIVE FARMTNG. 25 
 
 tion of universal nature. United with the matter of heat, 
 it may be artificially produced and presented as a trans- 
 parent, colourless, insipid, incombustible gas, incapable of 
 supporting flame or breathing. It may be made to unite 
 with oxygen (but of course only in certain definite pro- 
 portions) by the agency of electrical fire. It may easily 
 be procured by burning a bit of phosphorus in a confined 
 portion of air over water. The inflamed phosphorus 
 rapidly unites with the oxygen until it has exhausted all 
 that the air contains, then combustion stops, and the re- 
 maining gas is nearly pure nitrogen. Small creatures 
 soon die m it for want of oxygen. It combines in five 
 difl^erent proportions with oxygen, forming, in one instance, 
 nitric acid or aquafortis; and mixed, rather than chemi- 
 cally combined, with one-fifth its bulk of oxygen, it forms 
 the air we breathe. Though ammonia is not a simple 
 body, and, therefore, not to be classed with the present list, 
 it may not be inappropriate, after the mention of hydrogen 
 and nitrogen, to say that it results from the union of the 
 two. Ammonia exists in rain w^ater, and, as we shall 
 subsequently show, is an important auxiliary to vegetable 
 growth; it becomes developed in putrid urine or stable 
 compost; it is a colourless gas, with a strong pungent 
 odour. It dissolves easily in water, and is then called 
 hartshorn. It is very volatile; has all the common pro- 
 perties of soda and potash, combining readily with acids. 
 Sulphate of ammonia exists largely in the soot from coals. 
 From this source the " sal ammoniac " of commerce is pro- 
 cured. 
 
 Carbon. — Charcoal is the most usual, and best known 
 variety of carbon. It is black, soils the fingers, and is 
 more or less porous, according to the kind of wood from 
 which it has been formed. Coke, obtained by charring, or 
 distilling coal, is another variety. It is generally heavier 
 or denser than the former, though less pure. Black-lead, 
 or carburet of iron, there being in reality no lead in its 
 composition, is a third variety, still heavier and more im- 
 pure. The diamond is the only form in which carbon oc- 
 
26 PRODUCTIVE FARMING. 
 
 curs in nature in a state of perfect purity. That the dia- 
 mond is essentially the same substance with pure lamp- 
 black is a very remarkable circumstance. Charcoal, the 
 diamond, lamp-black, and all the other forms of carbon, burn 
 away more or less slowly when heated in the air; and, 
 combining with the oxygen of the atmosphere, form car- 
 bonic acid. 
 
 Oxygen, hydrogen, nitrogen, and carbon, form the ul- 
 timate elements into which all the organized part of all 
 vegetable and animal substances is resolvable. We say 
 organized: bones contain lime, and vegetables contain 
 earthy and saline matters; but these are not organized, 
 they are deposited in cells, or in a structure so arranged as 
 to contain them. 
 
 Chlorine, or Oxymuriatic gas, is, like oxygen gas, a 
 permanently elastic fluid. When pure, it has a greenish 
 yellow colour, and a very disagreeable odour and acid 
 taste. It may not be breathed, and burning bodies are ex- 
 tinguished by it. It destroys all vegetable and animal 
 colouring substances, as also the effluvium arising from the 
 putrefaction of dead animal matter. It does not exist 
 separately in nature, but is one of the components of com- 
 mon salt. 
 
 Fluorine. — This substance has such strong tendencies 
 to combination, that as yet no vessels have been found 
 capable of containing it in its pure form. It is one of the 
 elements composing the Derbyshire fluor spar or blue John. 
 This mineral is a fluate of lime, in other words, a com- 
 pound of fluoric acid and lime. Now, fluoric acid is itself 
 a compound of fluorine and hydrogen ; and lime is not a 
 simple body, but in reality the oxide or rust of a metal 
 named Calcium, from the latin word " Calx," signifying 
 lime. Fluoric acid may be obtained from the Derbyshire 
 spar by the action of sulphuric acid, which combines with 
 the lime in consequence of the greater affinity of the two 
 than exists between lime and fluoric acid, which by such 
 process may be separated. 
 
 Having disposed of these, we proceed to notice (not the 
 
PRODUCTIVE FARMING. 27 
 
 whole rano^e) but a few other simple substances found in na- 
 ture, and chiefly in the animal, vegetable, and mineral world. 
 
 Sulphur. — This is a solid substance, of a lipht yellow 
 colour, brittle and tasteless, and when rubbed, emitting a 
 peculiar odour. Melted and poured into cylindrical moulds 
 it forms the roll brimstone of commerce. It burns with a 
 pale blue flame in the open air, during which process it 
 combines with the oxygen of the atmosphere, and forms 
 sulphuric acid or oil of vitriol. Sulphur is found native in 
 Sicily, Italy, and Iceland, and in combination with metals 
 and earths in greater or less quantity throughout the min- 
 eral kingdom. It is a constituent of many vegetable and 
 nearly ail animal structure. 
 
 Phosphorus. — Phosphorus is most easily obtained by 
 burning bones to whiteness in an open fire. In this way 
 the animal matter is driven off and nearly pure phosphate 
 of lime (or a salt composed of phosphoric acid and lime) 
 remains. This phosphate of lime, reduced to powder, is 
 next mixed with oil of vitriol and water ; decomposition 
 ensues in consequence of the greater affinity which oil of 
 vitriol or sulphuric acid has for hme than the phosphoric 
 acid already in combination with it. Next, by evaporation, 
 the addition of powdered charcoal, and exposure of the 
 mixed mass to distillation, the liberated phosphorus is sepa- 
 rated into its two elements, (phosphorus and oxygen,) the 
 former of which distils over, and at a low temperature 
 becomes solid. Phosphorus may also be prepared from 
 urine. It takes fire at a heat considerably lower than that of 
 boiling water. Phosphorus has a w^axy consistence ; when 
 burned in oxygen gas, a very dazzling light is produced ; 
 and the result of the combination is phosphoric acid, just as 
 sulphur or brimstone, burnt in oxygen gas, produces sul- 
 phuric acid. Phosphoric acid combined with lime, forms 
 phosphateof lime, the solid inorganic constituent of bones. 
 Phosphate of lime is easily obtained by exposing bones to 
 a red heat in an open fire. Its first action is to blacken the 
 bones, converting its animal carbonaceous matter into 
 charcoal : if the heat be continued, the charcoal or carbon 
 
28 PRODUCTIVE FARMING. 
 
 unites with the oxy<ren of the atmosphere in the form of 
 carbonic acid gas, and the phosphate of lime remains beau- 
 tifully white, left in the shape and arrangement of the 
 organized cells it lately filled. Phosphate of lime is found as a 
 native mineral production in some parts of Ireland and else- 
 where. Phosphorus will dissolve in spirit of wine or in oil, but 
 is insoluble in water, under which fluid it is always preserved. 
 
 Iodine. — This simple substance is found existing as an 
 undecompounded element in the ashes of marine plants 
 after the extraction of the soda they contain. Sea- weed is 
 largely used on the coasts of England and Scotland as a 
 manure. Iodine is a dark-coloured solid, having somewhat 
 the appearanceof black-lead. It unites to all the metals upon 
 which its action has been examined, and combines with 
 oxygen, forming an acid. 
 
 Next, let us allude to earths and metals, or such forms 
 of them as fall within the range of simple elementary 
 bodies. We have already said that lime, ordinarily con- 
 sidered as an earth, is in reality a metallic oxide ; pure 
 soda, pure potash, calcined magnesia, pipe-clay, the base 
 of flint, and some other similar substances, are, in truth, 
 metals, united to oxygen in the same way as rust of iron is 
 a compound of iron and oxygen. Lime, then, or, in chemi- 
 cal language, " oxide of calcium," combined with various 
 acids, is a very abundant natural production, found widely 
 diffused over every part of the habitable globe, as limestone, 
 marble, chalk, fluor spar, plaster of Paris, gypsum, or ala- 
 baster ; these, under various names, being all of them com- 
 pounds of lime with the carbonic, fluoric, or sulphuric acids. 
 Besides these, lime, in combination with phosphoric acid, 
 enters very largely into the composition of the solid skeleton 
 or shell of animals. Pure lime is more soluble in cold than 
 in hot water, a fact not without its interest nor intention. 
 If chalk be exposed to a red heat, the carbonic acid, one of 
 its constituents, is expelled, and pure lime remains. Pure, 
 or caustic quicklime corrodes animal and vegetable sub- 
 stances, and is never found in them in an unmixed state. 
 Lime is one of the most infusible bodies known, but may 
 
PRODUCTIVE FARMING. 29 
 
 be made to melt by the joint action of the combustion of 
 oxygen and hydrogen gases. Lime has a powerful affinity 
 for water, and the combination is attended with the extri- 
 cation of great heat, as when lime is slaked for the builder. 
 In this process the water becomes solid, unites, not mixes, 
 with the lime, and in passing from the fluid to the solid state, 
 gives out the latent heat necessary to maintain fluidity. 
 This heat becoming suddenly sensible, is suflBcient to carry 
 off a portion of the water in vapour, the union of the lime 
 and the water producing a dry solid. The same chemical 
 union occurs when plaster of Paris, or dry sulphate of lime, 
 is mixed in certain proportions with water : the fluid solid- 
 ifies, and unites with the hme into the hard substance which 
 forms the common plaster images or casts hawked about 
 the streets by the Italians. Lime combines freely with 
 many acids, existing in this form as " muriate of lime" in 
 the water of the ocean. Of the application of earthy 
 minerals to the land, we will speak in its proper place. 
 
 Sodium. — This is the metallic base of common table or 
 rock salt, which is a compound of two elements, chlorine, 
 already alluded to, and sodium, with water. The metal 
 sodium has a lustre and colour very similar to silver, and is 
 so soft as to be pressed into leaves betw^een the fingers. It 
 may be obtained through the agency of the galvanic appa- 
 ratus. When thrown upon water it decomposes that fluid, it 
 soon becomes oxidized, or robs the water of oxygen, setting 
 its other constituent, hydrogen, at liberty, the action being 
 accompanied with a hissing noise. Chloride of sodium, or 
 common salt, is abundantly diffused over the world, both 
 as a solid mineral production, and as the principal ingredi- 
 ent in sea-water ; it is essential to healthy action, as well 
 in vegetable as in animal nutrition. If thrown upon hot 
 coals, salt crackles, because the w^ater it contains is not 
 chemically combined, but merely mixed or interposed be- 
 tween its particles, and so expanding by heat causes the 
 separation of those particles and the resulting sound. So- 
 dium united to oxygen, forms pure soda ; pure soda united 
 to sulphuric acid, forms the Glauber salt, so commonly 
 
30 PRODUCTIVE FARMING. 
 
 given to cattle ; pure soda united to carbonic acid, forms 
 the substance sold in the shops as " soda," and bought for 
 the purposes of the washerwoman. 
 
 Potassium, — This is the metallic brise of cgmmon pearl 
 ashes. If the pure metal be thrown upon water, like 
 sodium it swims on the surface, and darts violently hither 
 and thither, with the sudden extrication of flame. This 
 flame is burning hydrogen, and the phenomenon arises 
 from the great affinity of potassium for oxygen, abstract- 
 ing it from water, or all bodies that contain it. If the 
 metal potassium be united wnth oxygen, it forms pure, or 
 caustic potash, or oxide of potassium ; if pure potash be 
 united with carbonic acid, the result is carbonate of potash, 
 of which pearl ashes is an impure variety. United with 
 nitric acid, potash forms saltpetre, which is found very 
 abundantly as a natural product. Potash, combined with 
 oxalic acid, is found in sorrel, and other sour plants. Im- 
 pure carbonate of potash remains in the ashes of most 
 vegetables, and so largely in some of them, as to yield the 
 immense supply for trade. Potash, united with fatty or 
 oily substances, forms the various kinds of soap. 
 
 Silicon is another metal which, in union with oxygen, 
 forms silica, or siliceous earth, existing native in great 
 abundance, and forming the chief ingredient m flint, quartz, 
 and rock-crystal. From these substances silica may easily be 
 obtained, by first heating them to redness, and then throw- 
 ing them into water. For all common purposes, sand from 
 the glass-house will answer. It unites with potash, and 
 forms glass, and is insoluble in all acids, except the fluoric 
 acid, for which reason this acid is kept in leaden bottles. 
 Silica exists very largely in the hard coating of the sugar 
 cane. In the stem of wheat straw, silica is essential to the 
 firm, erect position of ^the plant ; consequently, if the soil 
 be deficient of silica, (a fact which is easily determined,) 
 the ear of corn will droop, upon a slender, short, and lanky 
 straw. 
 
 Jlluminium. — This metal, in combination with ogygen, 
 forms pure alumina. Alumina, more or less pure, exists as 
 
PRODUCTIVE FARMING. 31 
 
 a most abundant natural production, being found as a chief 
 constituent of clay^ for pottery and bricks. Crystallized, it 
 forms those precious gems, the ruby and sapphire : so that 
 the difference between a bit of charcoal and a diamond, is 
 a similar difference to that which exists between a bit of 
 clay and a precious jewel — merely a diversity in the ar- 
 rangement of particles of the same matter. 
 
 Barium. — A metal forming the base of the earth baryta, 
 and of the various acids in combination with that earth. 
 Carbonate of baryta is found native in Derbyshire. Pure 
 baryta, like lime, slakes when in contact with water; for 
 which it has so strong an affinity, that the heat of a forge 
 will not drive it off. 
 
 Magnesium, — The metallic base of the earth magnesia, 
 the calcined magnesia of the shops. In combination with 
 muriatic acid, it exists largely in sea-water. With sul- 
 phuric acid, magnesia forms the common Epsom salt, and 
 is found as a native magnesian limestone, in combination 
 with lime and carbonic acid. 
 
 Iron. — Iron is found native in many parts of the world, 
 and is also very abundant in combination with sulphur, 
 and many other substances, such as oxygen, forming ox- 
 ides ; also in further union with acids, forming carbonates, 
 sulphates, and phosphates. Green copperas is a sulphate 
 of iron. Rust of iron, produced by the action of the at- 
 mosphere, arises from the combination of the iron with 
 oxygen, derived from the air, and also with a portion of 
 carbonic acid from the same source, and so may be correctly 
 named carbonate of iron. 
 
 Lead. — Metallic lead is rarely found native, but is ob- 
 tained in large quantities by smelting the sulphuret, a min- 
 eral known by the name of galena. Lead is found also in 
 combination with oxygen and acids. 
 
 Copper. — This metal occurs very commonly native in a 
 state of perfect purity, sometimes in large masses, at other 
 times in a crystalline form. It is commonly found in com- 
 bination with sulphur, from which it is generally obtained. 
 Blue stone, used by the farrier, is a sulphate of copper. 
 
32 PRODUCTIVE FARMING. 
 
 Zinc. — Metallic zinc, sometiraes named spelter, is ob- 
 tained either from the impure carbonate, a native produc- 
 tion called "calamine," or from another natural compound, 
 the "sulphuret," or zinc blende. White vitriol used in 
 veterinary medicine, is a sulphate of zinc. The ores from 
 which it is smelted, exist largely in some districts. — Tin, 
 bismuth, antimony, arsenic, nickel, cobalt, and many other 
 metallic substances, might similarly be enumerated ; but 
 these, existing in comparatively minute quantities, may be 
 safely passed over. The elements found in vegetables are 
 but few. Oxygen, hydrogen, and carbon, form the great- 
 est part of their organized matter. Nitrogen, phosphorus, 
 sulphur, manganesura, iron, silicum, calcium, aluminum, 
 and magnesium, enter into their composition, or are found 
 in the agents to which they are exposed ; and these twelvBy 
 out of nearly sixty undecompounded elements, require to be 
 familiarly understood by the agricultural chemist. Life 
 gives a peculiar character to all its productions : the power 
 of attraction and repulsion, combination and decomposi- 
 tion, are subservient to it. A few elements, by the diver- 
 sity of their arrangement, are made to form the most dif- 
 ferent substances; and similar substances are produced 
 from compounds which, when superficially examined, ap- 
 pear entirely different. 
 
CHAPTER III. 
 
 Pi.ANTS and Animals are both alike endowed with Life • the Ele- 
 mentary Materials and many of the Proximate Principles of Ani. 
 mal and Vegetable matter are precisely identical — they have siini- 
 lar Organs essential to their growth and reproduction^ and are 
 nourished or destroyed by the same agencies. 
 
 If I dig up a stone and remove it from one place to an- 
 other, the stone will suffer no alteration by the change of 
 place ; but if I dig up a plant, and remove it, strip its 
 leaves, and leave the stem standing, or mutilate an animal, 
 — that plant or animal will instantly sicken, and perhaps 
 die. What is the reason of this ? Both have been per- 
 fected in connexion with the same common soil. If I 
 break the stone to pieces, though chemically, it may con- 
 sist of several elements, yet every individual fragment will 
 be found possessed of the original character of the whole 
 mass; it is only altered in shape and magnitude; but if I 
 tear off a branch from a plant, it will wither and lose the 
 properties of its parent stock. The mineral can only be 
 destroyed or changed by mechanical or chemical force ; 
 while the plant, like all animals, has been produced by 
 generation, has grown by nutrition, and been destroyed by 
 death, — in fact, it has been actuated by an internal power. 
 In what this internal power consists, we know not. Dif- 
 ferently modified, we meet with it in both plants and ani- 
 mals. Wherever we find it, we denominate it the " prin- 
 ciple OF life;" its presence forming a clear distinction and 
 boundary between the two great families of animals and 
 plants, and all else besides in the universe. A cabbage is 
 not less truly alive than the ox which feeds upon it. The 
 superiority of the animal over the plant consists chiefly in 
 this — the existence of mind or intellect ; and- correspond- 
 ingly, a brain and nerves, of which the plant is deficient. 
 
 3 
 
34 PRODUCTIVE FARMING. 
 
 Now, all living things are said to be organized ; that is, 
 made up oi various structures, evidently destined to answer 
 certain ends ; and these, taken together, compose the en- 
 tire plant or animal : as the root, sap vessels, bark, leaves, 
 and other organs of a tree ; and correspondingly, the bones, 
 muscles, blood-vessels, skin, and lungs of a horse, a man, 
 or of a sheep. But this description is not true of a piece 
 of limestone, or a lump of clay, and, therefore, it is said to 
 be inorganized. Hence, all the various bodies in nature 
 arrange themselves naturally under the two great divisions 
 of organized and vital, or inorganized and dead, without a 
 single exception. 
 
 In their more perfect forms, the distinctions between an- 
 imal and vegetable life are obvious enough. There is a 
 wide distinction between a horse chestnut and a chestnut 
 horse; but as we approach the contiguous extremities of 
 the animal and vegetable kingdoms, the distinction is not 
 so easy. There are some natural productions which have 
 been originally considered as minerals, afterwards as vege- 
 tables, and have at last been regarded as belonging to the 
 animal kingdom; less on account of any other property 
 they possess than their similarity of chemical and element- 
 ary constitution to the well-known ingredients of animal 
 matter. Sponges, and many fungous growths, are of this 
 character. 
 
 In what part of a plant the living principle chiefly exists, 
 or to what quarter it retires during the winter, we know 
 not; but we are just as ignorant in relation to animal life. 
 In both, it operates towards every point ; it consists in the 
 whole, and resides in the whole; and its proof of existence 
 is drawn from its resisting those putrefactive or chemical 
 agencies which instantly begin to operate as soon as the 
 plant or animal is dead. While life exists, a vegetable or 
 animal thrives and increases in its bulk ; a tree puts forth 
 annually a new progeny of buds, and becomes clothed with 
 a beautiful foliage of lungs, (every leaf being in itself a 
 distinct lung,) for the respiration of the rising brood, and 
 with an harmonious circle of action that can never be too 
 
PRODUCTIVE FARMING. 35 
 
 much admired, a perpetual supply of nourishment is fur- 
 nished first for its own growth, next for the growth and 
 perfection of animal life ; while, from its own decay, as 
 well as from the death of animal matter, there is formed, 
 in rich abundance, the means of new births, new buds, and 
 new harvests. In fact, every thing is formed for every thing, 
 and subsists, (if we may speak figuratively) by the kind in- 
 tercourse of giving and receiving benefits. Such is the 
 simple, but beauti ul, circle of nature. That which lives, 
 flourishes, decays, and dies, is not lost ; the great principle 
 of life only changes its form ; and the destruction of one 
 generation of plants or animals is but the necessary requi- 
 site to the support or existence of the next. 
 
 Carbonic Acm, Ammonia, and Water, yield elements out 
 of which are built up all the organized parts of plants ; 
 and it is no less true that these elements form the entire 
 organized structure of animals. This being the fact, w^e 
 should naturally suppose the conditions essential to the 
 growth of each are the same ; in fact, that the food con- 
 sumed by vegetables and animals would prove essentially 
 similar : and such is actually the case. The process of di- 
 gestion in an animal is precisely identical w^ith the process 
 of appropriation or nourishment in a plant. Certain inor- 
 ganic substances, salts and metallic oxides, serve peculiar 
 uses, as lime to give solidity to the bones of an ox ; and 
 silica, or the earth of flints, to serve the same end in wheat 
 straw. 
 
 We have already spoken of the elementary or ultimate 
 constituents of vegetables. Out of these are formed the 
 various immediate compounds which are found in them 
 The compound substances found in vegetables are, — 1. Al- 
 bumen ; 2. Gum; 3. Sugar; 4. Gluten; 5. Woody fibre; 
 6. Starch ; 7. Extractive ; 8. Tannin ; 9. Resin ; 10." Wax ; 
 11. Fixed and volatile oils ; 12. Bitter principle; 13. Free 
 acids ; and a few others ; to which must be added the 
 mineral, saline, or metallic substances they contain. 
 
 Out of the same elementary constituents of vegetable 
 and animal structure are formed the materials composing 
 
36 
 
 PRODUCTIVE FARMING. 
 
 the blood and all the secretions — fibrin, gelatin, mucus, al- 
 bumen; all the animal acids — spermaceti, hog's lard, train 
 oil, and other fatty substances ; ozmazome, urea, sugar of 
 milk; together with many other matters enumerated by 
 chemists, only some of which are peculiar to the animal 
 kingdom ; — so that there is no difference between albumen 
 obtained from a vegetable and that which forms, in nearly 
 a pure state, the white of an egg. Albumen in a solid 
 form constitutes the principal part of the almond, and of 
 the kernels of nuts. The juice of a West Indian plant 
 {Hibiscus esculentis) contains liquid albumen in such quan- 
 tities, that it is employed in Dominica as a substitute for the 
 white of eggs in clarifying the juice of the sugar cane. 
 Albumen is common to the vegetable as well as the ani- 
 mal kingdom, and may be easily distinguished from other 
 substances by its property of coagulating or becoming hard 
 and permanently solid by the action of moderate heat, or 
 of acids. It forms a constituent of the serum of blood, of 
 several of the animal secretions, and in a solid form of 
 some of the organized structures of the body. Its compo- 
 sition, from whatever source it may be obtained, is Carbon, 
 52 ; Hydrogen, 7 ; Oxygen, 23 ; and Nitrogen 15 parts, 
 (rejecting fractions,) in every 100. 
 
 Let us trace a few more of these comparisons, bearing 
 in mind that nitrogen, as one of the elements into which 
 both vegetable and animal compounds are ultimately re- 
 solvable, exists always in greater proportion in flesh, than 
 in grasses. All animal matters do not contain nitrogen ; 
 nor are all vegetable substances devoid of it. 
 
 Vegetable gum is analogous to animal mucus. Gum 
 is a substance which exudes from certain trees ; it appears 
 in the form of a thick fluid, but soon hardens in the air, 
 and becomes solid, when it appears white, or yellowish 
 white, and somewhat brittle. The characteristic properties 
 of gum are its easy solubility in water, and its insolubility 
 in spirit of wine. All the varieties of gum are nutricious 
 as food. Gum is composed of 43 carbon, 51 oxygen, and 
 6 hydrogen, in 100 parts, or nearly. Mucns, a secretion 
 
PRODUCTIVE FARMING. 37 
 
 found on the surfaces of the lining membrane of the intes- 
 tines, possesses the same characters ; and its composition 
 is nearly the same. It may be obtained by evaporating the 
 saliva to dryness; and is then similar to gum-arabic in its 
 general appearance, but rather more opaque. It may be 
 procured also by evaporating to dryness the fluid found in 
 the shell of the oyster, or water in which that animal has 
 been macerated. 
 
 Sugar is essentially the same, whether derived from the 
 maple-tree, the sugar-cane, the milk of animals, or even 
 from the urine in the disease known by the name diabetes. 
 Its composition is 28 carbon, 8 hydrogen, and 64 oxygen, 
 in 100 parts, differing not very widely from gum. Sugar 
 exists, naturally formed, in many plants and fruits, espe- 
 cially the sugar-cane. During the Peninsular war, it was 
 larp^ely manufactured from the juice of the beet-root, both 
 in France and Germany. It has also been obtained from 
 grapes, from manna, from carrots, and from honey. 
 
 Let us compare vegetable gluten w^ith animal gelatin. 
 First, of gluten. It may readily be prepared from wheat, 
 or from flour, by the agency of cold water, and pressing 
 out the starch. It has a grey colour; is elastic, ductile, 
 and tenacious ; soon decomposing when kept long in con- 
 tact with the air, emitting an offensive odour similar to that 
 of putrid animal matter. Gluten, when burnt, affords simi- 
 lar products to albumen, or white of egg, and differs little 
 from it in composition. It is found in a great number of 
 plants : in acorns, chestnuts, apples, rye, barley, wheat, 
 peas, and beans ; in the berries of the elder, and in grapes. 
 Gluten appears to be one of the most nutritive of the vege- 
 table substances ; and wheat seems to owe its superiority to 
 other grain, from the circumstance of containing it in larger 
 quantities. Animal gelatin, its counterpart from the ani- 
 mal kingdom, enters largely into the composition of many 
 of the animal solids ; such as horns, hoofs, and skin, the 
 organized structure of bone, cartilage, and tendon. Isin- 
 glass and common joiner's-glue are forms of gelatin, it 
 being readily distinguished from all animal principles by its 
 
38 PRODUCTIVE FARMING. 
 
 easy solubility in boiling water. Gluten and albumen, de- 
 rived from vegetables, differ from other vegetable products, 
 principally in containing nitrogen, and thus assimilating 
 very closely to the chemical character of animal matter. 
 Its composition is 47 parts of carbon, 8 of hydrogen, 27 of 
 oxygen, and 18 nitrogen, in 100 parts, or pounds. 
 
 Woody fibre is a substance remaining after the plant 
 subjected to analysis has been exhausted of all its soluble 
 materials by repeated boiling in water and spirit of wine. 
 It forms the bulk of vegetables. Its composition is 52 parts 
 of carbon, and 48 of hydrogen and oxygen, in such pro- 
 portions as form water, in 100 parts. Jinimal fibrin is a 
 principal constituent of the muscular, red or fleshy parts of 
 animals, and of the blood. It may conveniently be pro- 
 cured by stirring blood recently abstracted, during its coag- 
 ulation ; then washing the fibres till they become colourless, 
 or by digesting small pieces of lean meat in repeated por- 
 tions of water. As vegetable charcoal is made largely 
 from woody fibre subjected to the action of a close fire, so 
 animal charcoal may be similarly prepared from the mus- 
 cular parts of animals by the same agency ; or, indeed, 
 from any organized structure containing carbon. In ani- 
 mal fibrin, as it exists in muscle or in blood, one-half the 
 weight is carbon. Fibrin is white, inodorous, and insipid ; 
 w^hen dry, it is hard, brittle, and slightly transparent. 
 Strong sulphuric acid blackens it, converting it into char- 
 coal precisely as it does wood. In the roots of plants, in 
 the trunk and branches of trees, the bark and heart-wood, 
 the leaves and flowers, the great basis of the solid parts is 
 woody fibre. It forms by far the greatest part of the heart- 
 wood and bark ; there is less in the alburnum, still less in 
 the leaves and flowers. Fibrin holds a similar relation to 
 animal bodies. In 100 parts of fibrin there are 53 J of car- 
 bon, hydrogen 7, oxygen 19, and 19 of nitrogen i the 
 presence of nitrogen, or its addition, constituting the pecu- 
 liarity which distinguishes fibrin from woody fibre. 
 
 We have run the parallel far enough for ordinary pur- 
 poses. Of course, there are some proximate compounds in 
 
PRODUCTIVE FARMING. 39 
 
 animals and vegetables which are not common to both, 
 though, with the usual addition of another element, nitro- 
 gen, the most varying and unlike substances derivable from 
 the animal and vegetable world are compounded from the 
 same ultimate elements. Let us next briefly glance at a 
 few of these. 
 
 Starch. — Starch is procured from different vegetables, 
 but particularly from wheat, or from potatoes. To make 
 starch from wheat, the grain is steeped in cold water till it 
 becomes soft, and yields a milky juice by pressure ; it is 
 then put into sacks of linen, and pressed in a vat filled 
 w^ith water : as long as any milky juice exudes, the pre- 
 sure is continued, the fluid becomes gradually clear, and a 
 white powder subsides, which is starch. Arrow-root, tapio- 
 ca, and sago, are nearly pure starch. Starch, or, in its ab- 
 sence, coagulated mucilage, forms the greatest part of the 
 seeds and grains used for food ; and they are generally 
 combined with gluten, oil, or albumen : in corn with glu- 
 ten, in peas and beans with albumen, and in rape-seed, 
 hemp-seed, linseed, and the kernels of most nuts, with oils. 
 Its characteristic property is its easy solubility in boiling- 
 water, and its insolubility in that fluid when cold. The ulti- 
 mate composition of starch is, carbon 43J, oxygen 60, 
 hydrogen 6^ ; or, in other words, carbon 43|-, and oxygen 
 and hydrogen in such proportions as form water ; differing, 
 chemically, from gum, only in a very slight variation in 
 these quantities. 
 
 Extract, or the extractive principle, exists in almost all 
 plants. It may be procured in a state of tolerable purity 
 from saffron, by merely infusing it in water, and evapo- 
 rating the solution. It may likewise be obtained from 
 catechu, or terra Japojiica, a substance now imported in 
 immense quantities from India, and used in calico-printing. 
 This substance consists principally of astringent matter and 
 extract. By the action of water upon it, the astringent 
 matter is first dissolved, and may be separated from the 
 extract. There are almost as many varieties of extract as 
 there are species of plants. It is not, nor can it be used 
 
40 PRODUCTIVE FARMING. 
 
 singly as an article of food ; but is probably nutritive 
 when united to starch, mucilage, or sugar. Its con)po- 
 sition is carbon, hydrogen, oxygen, and a little nitrogen. 
 
 Tannin^ or the tanimig principle, may be procured by 
 the action of cold water on bruised grape-seeds, or pound- 
 ed gall-nuts, and by the evaporation of the solution to 
 dryness. It is a yellow, highly-astringent substance. If 
 tannin be distilled in close vessels, the principal products 
 are charcoal, carbonic acid, and inflammable gases, with a 
 minute quantity of volatile alkali. Hence its ultimate ele- 
 ments seem the same as those of extract, but probably 
 in different proportions. Tannin is not a nutritive sub- 
 stance, but is of great importance in its application to 
 the art of tanning. When skins (which are composed al- 
 most entirely of gelatin or jelly) are exposed to solu- 
 tions containing tannin, they slowly combine with that 
 principle ; their fibrous texture and coherence are preserv- 
 ed ; they are insoluble in water, and no longer liable to 
 putrefaction ; and, by subsequent processes of rolling and 
 drying, form leather. In general, in this country, the re- 
 quisite tannin is made from the bark of the oak; but 
 the barks of other trees, and the wood and leaves of many 
 shrubs, yield it abundantly. 
 
 Resin is very common in the vegetable kingdom. 
 One of the most usual species is that afforded by the dif- 
 ferent kinds of fir. When a portion of the bark is re- 
 moved from a fir-tree in spring, a matter exudes, which 
 is called turpentine. By heating this turpentine gently, a 
 volatile oil rises from it, known familiarly as " spirit of tur- 
 pentine." A more fixed substance remains, which is com- 
 mon yellow rosin. Resins are insoluble in water, but very 
 soluble in spirit of wine; in this respect reversing the cha- 
 racter of gum. Sandarac, copal, mastic, elemi, are resins 
 obtained from various trees ; and the list is very numerous. 
 Tar and pitch principally consist of resin in a partially de- 
 composed state. Tar is made by slowly burning the fir ; 
 and pitch, by the evaporation of the more volatile parts of 
 tar. One hundred parts of common resin contain 76 of 
 
PRODUCTIVE FARMING. 41 
 
 carbon, 13.3-lOths of oxygen, and 10.7-lOths of hy- 
 drogen. 
 
 Wax is found in a number of vegetables, from their 
 berries and the surfaces of their leaves. Its combustible 
 property, like that of resins, is well known. The wax of 
 the vegetable kingdom seems to be precisely of the same 
 nature as that afforded by the bee. Its constituents are, 
 carbon 81.7-lOths, oxygen 5^, hydrogen 12.6-lOths, in 
 100 parts. 
 
 Fixed oil is obtained by expression from seeds and fruits. 
 The olive, the almond, linseed, and rape-seed, afford the 
 most common vegetable fixed oils. Their common proper- 
 ties are well known. They are lighter than water ; and 
 many of them congeal at a lower temperature than that at 
 which water freezes. They all require, for their evapora- 
 tion, a higher temperature than that at which water boils. 
 The products of the combustion of oil are, water and car- 
 bonic acid gas. The fixed oils are very nutritive substan- 
 ces : they are of great importance in their applications to 
 the purposes of life. Fixed oil, in combination with soda, 
 forms the finest kind of hard soap. Let us compare the 
 ultimate analysis of olive or vegetable oil with that of sper- ^ 
 maceti oil, which is of animal origin : — 
 
 Olive Oil. 
 
 
 Spermaceti Oil. 
 
 
 Carbon, . . 
 
 77.2-lOths 
 
 Carbon, 
 
 50. 
 
 Oxygen, . 
 
 9.4-lOths 
 
 Oxygen, 
 
 5. 
 
 Hydrogen, . 
 
 . 13.4-lOths 
 
 Hydrogen, . . . . 
 
 45. 
 
 100. 
 
 100. 
 
 The greater proportion of hydrogen in spermaceti oil ren- 
 ders it a fitter fluid for combustion in lamps than vegetable 
 fixed oils ; but the ultimate composition of the two, as far 
 as the list of ingredients is concerned, is evidently the same. 
 
 Hog's lard, butter, spermaceti, may be regarded as ani- 
 mal fixed oils. 
 
 Volatile, or essential oils, differ from fixed oils, in being 
 capable of evaporation by a much lower degree of heat 
 Volatile oils give the peculiarity of odour to the pepper- 
 mint plant, to camomile, and numberless other shrubs and 
 
 3* 
 
42 PRODUCTIVE FARMLXG. 
 
 trees; existing in the flowers of some of them, and in the 
 leaves and inner bark of others. Thousands of minute in- 
 sects may usually be seen in the stalk and leaves of the 
 rose ; but none of them are ever observed on the flower. 
 One reason for the existence of fragrant volatile oil in 
 plants may be, the preservation of the parts destined to the 
 propagation of the species from the destructive ravages of 
 insects and animalculse which feed on the bodies of plants. 
 So, those woods that contain aromatic oils are remarkable 
 for their indestructibility, as cedar, rose-wood, and cypress. 
 The volatile oils inflame with more facility than fixed oils; 
 and afford, by their combustion, different proportions of the 
 same substances — namely, water, carbonic acid, and char- 
 coal or carbon. Volatile oils consist of carbon, hydrogen, 
 and oxygen ; but, as yet, no accurate experiments have de- 
 cided their relative proportions. 
 
 The hitter 'principle is very extensively diffused in the 
 vegetable kingdom. It is found abundantly in the hop, in 
 the common broom, in camomile, and in quassia. The 
 natural bitter principle is of great importance in the art of 
 brewing. It checks fermentation, and preserves fermented 
 liquors, and doubtlessly plays an important part in the 
 healthy nutrition of the living vegetable. An intensively 
 bitter substance is found in bile, or the fluid secreted 
 by the liver of animals. The gastric juice, or fluid secret- 
 ed by the stomach, is not only the principal solvent in di- 
 gestion, but has the same antiseptic property, or resists pu- 
 trefaction as strongly as the vegetable bitter principle. 
 
 Systematic writers on chemistry have enumerated a 
 long list of proximate constituents, both of animal and 
 vegetable structure. Many of them, as we have seen, are 
 but the counterparts of each other. It is needless to spe- 
 cify them all. 
 
 The earths found in plants are four, all of them, as 
 previously related, of metallic origin. These are, l^^, Sil- 
 ica, or the earth of flints, the base of which is the metal 
 silicon ; 2d, Alumina, or pure clay, the base of which is 
 the metal aluminium ; 3c/, Lime, the metallic base of which 
 
PRODUCTIVE FARMING. 43 
 
 is calcium ; and, Atlily, Magnesia, the metallic base of 
 which is magnesium. All of these are similarly found in 
 animals ; among them, lime, most largely in their bones and 
 shells. Some insects are almost entirely composed of sil- 
 ica : iron, existing in peat-mosses and in many vegetables, 
 gives the red colour to the blood. None of these exist in 
 a free or uncombined state, in either the vegetable or ani- 
 mal world ; most commonly in combination with acids, of 
 which we may observe, that some plants contain free veg- 
 etable acids in large proportion, as the common sorrel or 
 sour-leaf The applications of the vegetable acids are 
 well known. The agreeable taste and wholesomeness of 
 various vegetable substances used as food, materially de- 
 pend upon the vegetable acid they contain. Phosphoric 
 acid (united to lime in bones) is found free in the onion ; 
 and the sulphuric, muriatic, and nitric acids, though they 
 cannot with propriety be considered as vegetable products, 
 exist in many saline compounds, as part of the inorganic 
 constituents of plants as well as animals. They are all 
 variously compounded of carbon, hydrogen, and oxygen. 
 Then, too, the saline compounds found in plants correspond 
 with many similar compounds found in animals. Potash 
 and soda, blended with acids, are found in blood, in the va- 
 rious animal secretions, in the leaves and stalks of vegeta- 
 bles; sparingly in animal matter, very largely in sea-w^eed 
 yielding soda, and in the ashes of burnt wood yielding 
 potash. 
 
 Plants, like animals, are produced by ordinary genera- 
 tion ; and though we meet with various instances of pro- 
 duction by the generation of buds and bulbs, or of slips and 
 oiFsets, the similarity, instead of being liereby diminished, 
 is only drawn the closer ; for we meet with just as many 
 instances of the same variety of propagation among ani- 
 mals. Many species of worms are capable of increase 
 by buds, bulbs, or offsets; and some of these animals, like 
 the house-leek and various grasses, by spontaneous sepa- 
 ration. A twig of myrtle will live and grow, if placed in 
 the ground, because it contains in itself all the parts of a 
 
44 PRODUCTIVE FARMING. 
 
 perfect plant ; but that is independent of the provision na- 
 ture has made for the propagation of the plant naturally, 
 from the seed buried in the earth. Something approach- 
 ing very closely to the character of a sexual, or reproduc- 
 tive system of organs, is visible in the flowers of plants. 
 The pistil is the organ which contains the rudiments of the 
 seed ; but the seed is never formed, as a reproductive germ, 
 without the influence of the pollen, or dust on the anthers. 
 This mysterious impression is necessary to the continued 
 succession of the different vegetable tribes. It is a feature 
 which extends the resemblances of animal and vegetable 
 existence, and establishes, on a great scale, the beautiful 
 analogy of nature. Seeds which are shed devoid of this 
 fructifying dust, are precisely analogous to eggs over which 
 the influence of the male bird has never been exerted. 
 Vitality is therefore essential to the germination of seeds : 
 life will remain dormant, inert for an indefinite period, — 
 and then change its form into that of active vitality, if that 
 seed be placed under the action of moisture, heat, and air. 
 So that the scriptural inquiry, " How^ can a seed quicken, 
 unless it die ?" is not to be taken as the enunciation of a 
 scientific truth, but as an illustration drawn from the ordi- 
 nary apprehensions of mankind. 
 
 The utmost period of time to which seeds may be kept, 
 and be enabled to retain their life, and, consequently, their 
 power of growth, has not been accurately determined ; but 
 we have proofs enough to show that the duration may be 
 very long. A paper of melon seeds, found in the year 
 1762 in a cabinet of Lord Mortimer, and apparently col- 
 lected in 1660, were then sown, and produced excellent 
 fruit ; and, more latterly, seeds buried in the ruins of Her- 
 culaneum, and others brought from Egypt, — found in the 
 tombs that are more ancient than the time of Moses, — have 
 been proved to retain their vitality. Animal seeds, or, 
 more properly, eggs, when perfectly impregnated, appear 
 capable of preservation quite as long. This inert condi- 
 tion of seeds is not unlike what occurs in the hollows of 
 our waste lands, in reference to animal matter. When 
 
PRODUCTIVE FARMING. 
 
 45 
 
 these have been for some time filled with stagnant Avater, 
 we not unfrequently find minute eels, minnows, and water 
 insects there, and wonder how they could get into such a 
 situation. But the mud which has been emptied out of a 
 fish-pond has been, perhaps, thrown into these very hol- 
 lows ; or the eggs of the animals or insects have been carried, 
 mixed with other materials, into the same place, and then 
 waiting, it may be, year after year, the accidental, yet ne- 
 cessary, circumstances of warmth, water, light, and air, 
 they have been stimulated to active life. One species of 
 locust appears, m numbers, only once in seventeen years ; 
 and the palmer-worm once only, in similar numbers, in 
 thirty years. Something analogous to this occurs in refer- 
 ence to various species of grub and fly, as observed by 
 practical farmers ; and the reason of it is, that the integu- 
 ment, or outer covering, of many minute ova, ensures their 
 protection and their vitality during long periods. The eggs 
 of the gad-fly could never be hatched on the horse's back : 
 their covering preserves them entire and vital, till, by the 
 itching sensation their presence excites, the animal is 
 tempted to lick the spot, and so convey them to his stom- 
 ach, the only place where it is destined they should come 
 to maturity. Numberless small fish are seen in the salt 
 pans at a village, in Hesse Darmstadt : the ova of these 
 fish have been conveyed there by birds, and, it so happens, 
 are deposited in a place, where the necessary conditions 
 exist for their development. 
 
 The essential difference between the egg of a barn-door 
 fowl, and the ovum or egg, which ultimately becomes a 
 calf, a foal, or a human being, is, that the one, after the 
 stimulus of impregnation has been applied to it by the male, 
 comes to maturity within the body of its parent ; in the 
 other instance, it is hatched after its expulsion. In fish and 
 in frogs, the spawn, or ova, is first expelled, then the male 
 passes over it. The seeds of plants are exactly analogous to 
 eggs ; in ordinary instances the germs and the fecundating 
 material which ensures reproduction, being both found in the 
 same flower, and, of course, attached to the same stalk. 
 The various species of fruit are but contrivances for the 
 
46 PRODUCTIVE FARMING. 
 
 shelter and preservation of seeds, as the pippins of the ap- 
 ple, or of the orange and lemon : these, when fully ripe, 
 left to themselves, would fall, become rotten, or, in other 
 words, subjected to common chemical agencies and expos- 
 ing the seed within, form, in the first instance, a manuring 
 material for the perpetuation of the plant or tree which 
 had yielded it. 
 
 Plants derive all their sustenance from the spot on 
 which they are placed ; and, solely for this reason, are not 
 provided with a pecuharity which distinguishes animals, 
 namely, a set of movable levers or bones, destined to 
 carry them about from place to place in quest of food, and 
 of muscles, or red, fleshy, contractile organs, intended to act 
 upon those passive levers: and yet there are some plants 
 that seem fairly entitled to the character of locomotive or 
 migratory. A familiar instance of this occurs in the straw- 
 herry genus : such plants grow from a new bulb, or knob, 
 or radicle, while the old root dies away ; in consequence of 
 which, we can only conclude that the living principle of the 
 plant has quitted an old, decayed, and ruinous mansion, to 
 take possession of a new one ; so much so, that were a per- 
 son to plant the orchis, or the devil's-bit, in his garden, and 
 to search for it in the same spot, after an interval of seven 
 years, he would find it several hundred yards from the spot 
 where he had planted it. 
 
 There are some creatures that throw off their outer cov- 
 reing annually : so the shrubby cinquefoil, indigenous to 
 Yorkshire ; and other plants and trees, which, sending 
 forth, every spring, new colonies, by means of runners, 
 (as we call them,) shortly obtain a settlement for themselves, 
 and break off all connexion with the parent stock. 
 
 The blood of plants, like that of animals, is of an ex- 
 tremely compound character. If blood be allowed to stand 
 n a vessel, it soon separates into a clot, and a fluid in which 
 that clot floats. Each of these is again divisible into seve- 
 ral other matters. So with the fluid that circulatesin the 
 vessels of a tree. And, as from blood the various dissimi- 
 lar solid and fluid secretions and excretions are formed, 
 
PRODUCTIVE FARMING. 47 
 
 building up the animal fabric, — as bone, muscle, bile, 
 urine, jelly, — so, from this common current of vitality, 
 the sap, plants, like animals, secrete a variety of sub- 
 stances of different, and frequently of opposite pow- 
 ers and qualities — substances nutritive, medicinal, or dc" 
 structive. The flesh of the viper is healthful, his poison is 
 deadly ; the root of the Indian cassava is poisonous, its 
 leaves are eaten as ordinary food. Every one is familiar 
 with the fact, that some of our domesticated animals will 
 eat with impunity vegetables that would be poisonous to 
 others. Then, too, how close is the analogy between the 
 torpidity of the squirrel, or the dormouse, or the swallow, 
 during the winter, and that of deciduous plants during 
 the same season : we know, that if proper care be exer- 
 cised, they may be removed in that state without endan- 
 gering their vitality. Many animals are amphibious — they 
 can live equally well on land or in the water; and the vege- 
 table world is not without illustrations of a similar power. 
 Indeed, the instances of resemblance between animal and 
 vegetable life are innumerable. Some vegetables, like a 
 few birds, more insects, and most of our forest beasts, ap- 
 pear to sleep through the day, and become active at night; 
 while the greater number of them, like the great ma- 
 jority of animals, fold or hang their leaves at sunset, and 
 appear invigorated with the return of morning. Like ani- 
 mals, the duration of their existence is equally various. 
 
 We have already observed, that plants and animals con- 
 vert the materials of nutriment they receive into their own 
 substance precisely by the same agency, and that there is 
 no essential difference between the ultimate composition of 
 the requisite materials in either instance. If this be so, as 
 in the further progress of this inquiry we shall unquestion- 
 ably prove, it would be fair to expect that the digestive 
 organs of animals, — in fact, all that is connected with re- 
 production and growth, — have their counterpart in plants; 
 and such is actually the case. Let us briefly review the 
 anatomy, or organized structure, of a plant, and compare 
 that structure with the anatomy of a horse. 
 
48 PKOUUCTIVE FARMING. 
 
 Every plant, examined as to external structure, displays, 
 at least, four systems of organs, or some analogous part. 
 First, the Root ; Secondly, the Trunk and Branches, or 
 Stem ; Thirdly, the Leaves ; and. Fourthly, the Flowers 
 or Seeds. 
 
 The stem of any tree consists of the pith in the centre, 
 the wood surrounding the pith, and the bark which 
 covers the whole. A tree completely divested of bark, is 
 precisely in the predicament of an animal deprived of its 
 hide. The pith consists of bundles of minute hollow tubes, 
 or vessels arranged horizontally ; the wood and inner bark, 
 of long tubes or vessels bound together in a vertical posi- 
 tion, so as to be capable of carrying vegetable blood up 
 and down between the roots and leaves. When a piece of 
 wood is sawn across, the cut ends of these tubes are as dis- 
 tinctly perceptible as the divided arteries and veins in the 
 stump of an amputated limb. Branches are only prolong- 
 ations of the stem, and have the same character. 
 
 The bark of the stem and root is divisible, like the cov- 
 ering of animals, into epidermis, (analogous to the scarf 
 skin which rises over a blister,) and tnce skin, or inner 
 bark, which alone is vascular and vital. In forest trees, 
 and in the larger shrubs, the bodies of which are firm, the 
 outer bark, epidermis, or scarf skin, is a part of little im- 
 portance ; but in reeds, grasses, and plants having hollow 
 stalks, as wheat and oats, it is of great use, and is exceed- 
 ingly strong, from the provision of its containing siliceous 
 earth, or the oxide of a metal, as already stated. The 
 analogy between this contrivance and the shell of the lob- 
 ' ster, or the covering of insects, is very obvious. 
 
 As the 7^oot tapers away, the pith gradually disappears, 
 the bark thins out, the wood softens, till the white tendrils, of 
 which its extremities are composed, consist only of a colour- 
 less, spongy mass, in which the vessels or tubes that carry 
 on the circulation lose themselves. 
 
 The leaf is an expansion of the twig. Each separate 
 leaf is precisely analogous in its action to the gills of a 
 fish, or the lungs of an ox, or of a human being. The 
 
PRODUCTIVE FARMING. • 49 
 
 fibres \vhich are seen to branch out from the base over the 
 inner surface of the leaf, are prolongations of the vessels 
 of the wood, precisely as the lung of an animal is but an 
 outspread division of blood vessels. A powerful sucking 
 and forcing pump called the hearty is essential to drive 
 human blood along large vessels to its ultimate division; 
 but the vessels of plants are capillari/, that is hair-like, 
 exceedingly minute, and therefore a central power or heart 
 is not necessary. So there are capillary vessels in animals, 
 and there the action of the heart is not so sensibly felt. 
 Their minuter blood vessels are believed by some to be 
 contractile. The green exterior portion of the leaf is a 
 continuation of the inner bark, and communicates directly 
 with its vessels. Most of the vessels of the living plant 
 are full of sap or vegetable blood in almost continual mo- 
 tion. In spring and autumn the motion is more rapid ; in 
 winter it is sometimes scarcely perceptible. From the 
 spongy part of the root the sap ascends through the vessels 
 of the wood in virtue of that capillary attraction already 
 adverted to, until it is diffused over the inner surface of the 
 leaf. By the vessels in the green of the leaf it is returned 
 to the bark, and through the vessels of the inner bark it is 
 returned to the root. In man and four-footed animals the 
 blood is driven from the heart along the arteries, and returns 
 back by the veins; but previously to being sent along the 
 circulation a second lime, it is driven into the lungs, is 
 there subjected to the action of the air, (whence the neces- 
 sity for breathing,) and then, returned to the other side of 
 the heart, is agaki fitted to recommence its journey. Ani- 
 mals derive a considerable portion of their nutriment from 
 the change effected on the air by the action of the lungs : 
 something is absorbed as well as given out. The leaves of 
 plants perform the same oflnce. In the sunshine, the leaves 
 are continually absorbing carbonic acid as well as other 
 matters from the air, and giving out oxygen gas. In 
 breathing, carbonic acid is given off, and not triflingly. 
 The air becomes instantly poisonous, if that gas accumu- 
 late as rapidly as it did when some hundreds of our brave 
 
50 PRODUCTIVE FARMING. 
 
 countrymen were pent up in the confined space of the 
 ^' black-hole" at Calcutta. The leaves, then, are con- 
 tinually appropriating carbon, the basis of charcoal, from 
 the atmosphere. When night comes, this process ceases, 
 and they begin to absorb oxygen and give off carbonic 
 acid. Hence the mischief of placing large plants, in great 
 numbers, in bedrooms. It would result from the above ar- 
 rangement, that plants grow very little, perhaps not at all, 
 during the night. Now, during the summer months, when 
 they are provided with leaves, the days are long, the nights 
 short ; in winter, when plants are torpid or stationary, the 
 nights are long, and the day comparatively brief. Sun- 
 shine is necessary, in order to enable plants to decompose 
 carbonic acid and appropriate the carbon. It is owing to 
 this law, that in the cold northern regions where, in their 
 highest latitudes, the sun once risen never sets again during 
 the whole of their short summer, vegetation almost rushes 
 up from the soil ; almost literally, plants may be seen to 
 grow. The green leaves are continually gaining from the 
 air and never losing ; ever taking in and never giving off 
 carbon, since no darkness interrupts or suspends their labors. 
 Every child is led to regard the root of a plant as the 
 organ from which the vegetable grows ; not merely as at- 
 taching it in the erect position to the spot, but as forming 
 the medium of communication between all that is above 
 ground, and the food the soil is supposed to yield. But it 
 is not so obvious to us, who, in many senses, are but child- 
 ren of a larger giowth, that the leaves of an oak or an ash 
 spread their broad leaves into the air for the very same pur- 
 pose as the roots diffuse their fibres through the soil. The 
 only difference is, that while the roots absorb chiefly liquid, 
 the leaves inhale almost solely gaseous food. The human 
 lungs expose the blood to air just as, in the leaf, the sap is 
 submitted to the same agency ; and in each instance there 
 is a double use to which these organs are destined : they 
 not only change the character of the circulating fluid, but 
 permit, by the decomposition of air, the absorption of some 
 of its elements as food for the animal or plant. So that, 
 
PRODUCTIVE FARMING. 51 
 
 in truth, we live and are nourished partly upon the air we 
 breathe^ and so is a cabbage upon the atmosphere it decom- 
 poses. If the experiment be repeated — it has often suc- 
 succeed— that of burying the branches of certain trees in 
 the soil and elevating the roots in the atmosphere, turning 
 the vegetable upside down — there is as it were an inversion 
 of its functions — the roots will produce buds and leaves, 
 and the branches shoot out into root-like fibres and tubes. 
 The experiment succeeds well with the willow. 
 
 Though plants give out in the night carbonic acid, this 
 process does not go on so rapidly, or to such an extent, as 
 to destroy the balance in their favour of w^hat has been ab- 
 sorbed during the day. The quantity absorbed through the 
 leaves varies with the season, the climate, and the kind of 
 tree ; it is also modified by the nature of the soil. It has 
 been ascertained, however, that in our climate, on an 
 average not less than from one-third to three-fourths of 
 the entire quantity of carbon contained in the crops we 
 reap from land of average fertility, or (pretty nearly) the 
 amount of charcoal a burnt hay-stack would yield, is really 
 obtained from the air. 
 
 The varied and equally important uses of a leaf appear, 
 to the contemplative mind, singularly beautiful. 
 
 " In human works, though laboured on with pain, 
 A thousand movements scarce one purpose gain ; 
 In God's, one, single, can its ends produce, 
 Yet serves to second, too, some other use." 
 
 Then, too, the contrivance of so many expanded leaves ! 
 The air contains only one gallon of carbonic acid in every 
 2500; and this fortunately, rather w^e ought to say de- 
 signedly, only in a state of mixture, not of combination, 
 with the elements of the atmosphere, and therefore more 
 easily separable; were the proportion larger, it would 
 prove poisonous to the animals that live in it, deriving also 
 a portion of their nourishment from another element of the 
 atmosphere equally essential to plants. Now, in order to 
 catch this minute quantity of carbonic acid, the tree hangs 
 out thousands of square feet of leaf, in perpetual motion 
 
52 PRODUCTIVE FARMING. 
 
 through the ever-moving air; and thus, by the conjoined 
 labours of millions of pores, the substance of whole forests 
 of solid wood is slowly extracted from the fleeting winds. 
 Is not this wonderful ! Green stems, and stalks of grasses, 
 absorb carbonic acid as the leaf does ; and thus a larger 
 supply is afforded when the growth is most rapid, or when 
 the short life of the annual plant demands much nourish- 
 ment in a limited time. The slender and comparatively 
 dry leaves of the pine and the cedar perform the same func- 
 tions as the large and juicy leaves of the fig-tree, the cab- 
 bage, the walnut, or the rhubarb plant. That plants 
 derive so large a proportion of their nutriment, not from 
 the soil, but from the air, is evident from observing the 
 habitudes of many found in hot climates, which refuse to 
 vegetate except in a soil so dusty that no moisture can be 
 extracted from it, and perish if water be ignorantly supplied 
 to them. A well-known Jamaica shrub was long propa- 
 gated in our own stoves by cuttings, which, though freely 
 watered, could never be made to produce any signs of 
 flowers or fruit, notwithstanding that the cuttings were 
 several feet in length every season. By accident, a pot 
 with young cuttings was mislaid and forgotten in the royal 
 garden, and having no water given it, it was thereby re- 
 duced to its healthy dryness, and then every extremity was 
 seen to produce a flower. It is an opinion common to 
 many able men of the present day, that many plants derive 
 the whole of their support from the surrounding atmos- 
 phere ; if this be true of some, it is partially true of all, 
 and must very materially modify all our plans intended to 
 increase the product of the soil. There are, we say, some 
 plants which have no root whatever, as in the prickly-pear 
 or Indian fig; many are attached only to the hard surface 
 of a stone, and propagate their kinds by offsets, without 
 any other vegetable organs. Now there are some quad- 
 rupeds that appear to derive nourishment in the same way. 
 The sloth never drinks : it imbibes moisture by its skin, it 
 trembles at the feeling of rain ; so the olive cavy, and the 
 ostrich, are noted by the Arabs as avoiding water, and yet 
 
PRODUCTIVE FARMING. 
 
 53 
 
 these creatures are as juicy and well supplied with fluids 
 as any with which we are acquainted. 
 
 If leaves are necessary for the existence of the indivi- 
 dual tree, the flowers are necessary as generative organs 
 for the continuance of the species. Even in that class of 
 plants where no flowers are distinct, still there is every rea- 
 son to believe that the production of the seed is effected in 
 the same way as in other plants. Mosses and lichens, which 
 belong to this family, have no distinct roots, but they are 
 furnished wi.h filaments which perform the same functions; 
 and even in mushrooms there is a system for the absorption 
 and exposure of the sap to the air. Of all parts of plants 
 the flowers are most refined, the most beautiful in their 
 structure, and appear as the master-work of nature in the 
 vegetable kingdom. The elegance of their tints, the va- 
 riety of their forms, the delicacy of their organization, and 
 the adaptation of their parts, are all calculated to awaken our 
 curiosity and excite our admiration. The ancients had ob- 
 served, that diff'erent date-trees bore different flowers; and 
 that those trees producing flowers, containing in their cen- 
 tre organs termed by botanists ^' pistils,^' bore no fruit un- 
 less in the immediate neighbourhood of such trees as pro- 
 duced flowers differently arranged in their central structure, 
 and containing " stamens " The great naturalist, Lin- 
 naeus, has arranged the whole Vegetable Kingdom into 
 twenty-four classes, as deducible from the numbers of these 
 sexual organs in each flower. The numbers of the stamens 
 and pistils in each, their arrangements or their division, are 
 the circumstances which guided him, and enabled him to 
 form a system of botany admirably adapted to assist the 
 memory, and denoting well the analogies of all the essen- 
 tial parts of plants. 
 
 The SEED, the last production of vigorous vegetation, is 
 wonderfully diversified in form. Being that part which is 
 of the highest importance, it is found defended above all 
 other parts of the plant ; sometimes by soft pulpy sub- 
 stances, in addition to a hard shell, as in apricots and 
 plums ; by thick membranes, as in common garden peas 
 
54 PRODUCTIVE FARMING. 
 
 and beans ; by hard shells, or a thick coating, as in corn 
 and grasses. So, similarly, the eggs of the ostrich, which 
 are destined to be hatched by the sun in the sand where 
 they are deposited, are invested with a strong shell, not 
 firmer, comparatively, than the encasement surrounding 
 every one of the myriads of ova or eggs in the roe of a 
 cod-fish or herring. If w^e were to pursue the analogy 
 more closely still, between the structure of a grain of w^heat 
 and that of the egg of a bird or the ovum of a quadruped, 
 we should find the parallelism singularly minute and exact ; 
 but this is the province of the physiologist : it is enough 
 for our purpose to cite a familiar illustration. When pota- 
 toes are cut in pieces for seed, every gardener know^s that, 
 if each separate piece have not an " eye" upon it, the frag- 
 ment will not grow^ If it vegetate, it will be from that 
 living spot or " eye :" the remainder wall serve to minister 
 nutriment to the infant plant before it can pierce the soil ; 
 it will strike upwards and downwards; the original bit of 
 potato will be absorbed, or perish. So, a common garden 
 bean is divisible into two equal halves or lobes, which form 
 the organ of nourishment ; but the young plant springs not 
 from these, but from the plume or small white point be- 
 tween their upper part, and the young root is found like a 
 small curved cone at the other end of the seed. In wheat, 
 and many grasses, the organ of nourishment is not divisible 
 as in a bean ; but the same principle holds true not only of 
 all seeds, but of bird eggs, and the rudimentary ova of all 
 animals. 
 
CHAPTER IV. 
 
 Of the Elementary Composition of Water ; of the Composition of the 
 jitmosjjhere ; and of the artificial Application of Water to Grass 
 Lands. 
 
 We have already traced some of the more prominent 
 analogies obviously existing between vegetables regarded 
 as alive, and animals. We have shown that the ultimate, 
 and many of the proximate, elements of both are the same 
 — that they are nourished or destroyed by the same agen- 
 cies. Before we describe minutely the nature of the pro- 
 cess of nutrition and growth, it is necessary to understand 
 the chemical composition of the atmosphere, which is re- 
 lated similarly to lungs as to leaves; and of water, neces- 
 sary alike to plants as to animals. 
 
 If one measure of hydrogen gas, and half as much 
 oxygen gas, or, by weight, eight grains of oxygen gas, and 
 one grain of hydrogen, be mixed in a dry glass over mer- 
 cury, and the mixture set on fire, the result will be the for- 
 mation of 'pure water. So water is formed, and is some- 
 times seen collected, from the burning of the common 
 carburetted hydrogen, in the street or shop gas-lamps -, the 
 effect being nothing more nor less than the combination of 
 the oxygen of the air with the burning hydrogen. Water 
 is the result of their union, and combustion, or burning, 
 EFFECTS that union. The gas in the pipes would not, could 
 not, burn, if a free supply of air, or rather of oxygen, con- 
 tained in that air, were cut off; and water is the product 
 of their union. So that perfectly pure water is, chemically 
 speaking, not a simple undecompounded element, but a 
 compound of two elements — oxygen and hydrogen ; both 
 of which, as elements, enter largely into the composition 
 of both animal and vegetable matter. Oil and fat owe 
 
56 PRODUCTIVE FARMING. 
 
 their utility in yielding light in lamps to the presence of 
 hydrogen. Its presence causes turpentine and rosin to blaze 
 and burn readily ; while oxygen is equally an ultimate in- 
 gredient in all vegetable and animal substances. These 
 details may appear scientific; but the action of manure is 
 not to be understood without them, or rather the nature of 
 vegetable and animal growth, and all that favours or 
 retards it. 
 
 The purest natural water we can obtain is procured 
 by melting snow, or collecting rain-water, in stations dis- 
 tant from the smoke of a town. If pure water be requisite 
 for the experiments of a chemist, it is generally obtained 
 by distilling rain-water in glass vessels, — that is, raising it 
 into steam by heat, then allowing that steam to condense, 
 by passing it through cold pipes. The characters of abso- 
 lutely pure water are — that it is perfectly transparent and 
 colourless, limpid, not sparkling, insipid, unpleasant, and 
 sickly to the taste, and is lighter than common river or 
 spring water. One hundred cubic inches of water weigh 
 252.^ grains; it is 828 times heavier than air ; and when 
 expanded into steam, occupies 1700 times its previous space. 
 Steam is not nearly so heavy as the air. Water readily 
 absorbs many gases : what is called soda-water, is water 
 impregnated with fixed air, or carbonic acid gas. It ab- 
 sorbs ammoniacal gas readily in large quantities, forming 
 what is sold in the shops as spirit of hartshorn. 
 
 Of the constitution of Sea Water, the proportions and 
 nature of its saline ingredients, one of their final uses in 
 vegetation, and especially the relatively large proportion 
 of carbonic acid it contains, we will speak, when advert- 
 ing to the necessity and wisdom of such arrangement. 
 
 Neither is the atmosphere animals breathe and decom- 
 pose, and in which living plants carry on analogous opera- 
 tions, a simple element. Air is a compound of two gases, 
 oxygen and nitrogen^ in the proportion of two parts of iii- 
 trogeii to one of oxygen. 100 cubic inches of air weigh 
 30 grains. The atmospheric pressure of the air upon the 
 earth's surface, at the level of the sea, is equal to a weight 
 
PRODUCTIVE FARMING. 67 
 
 of 15 pounds upon every square inch, and is capable of 
 supporting a column of water 34 feet high, or of mercury, 
 30 inches. For this reason, a pump will not work, if the 
 depth of the shaft be greater than 34 feet; and the height 
 to which the quicksilver will rise in the weather-glass al- 
 ways corresponds to the pressure of the atmosphere; that 
 is to say, the weight of the mercury in the tube is exactly 
 equal to the weight of a column of air the same thickness, 
 only the height of the atmosphere. The air receives its 
 heat entirely from the earth : hence the phenomena of cold 
 which we perceive the higher we ascend from the earth's 
 surface. 
 
 If water be passed through a red-hot gun-barrel, it \vill 
 be decomposed ; its oxygen will unite with the metal, its 
 hydrogen will escape, and may be collected in the form of 
 a gas, and preserved in a bladder. Many similar experi- 
 ments demonstrate the composition of water. It may be 
 made, in fact is made, in almost every instance where a 
 combustible body unites with the oxygen of the air : it may 
 be separated into its elements, unmade, so to speak, by a 
 variety of processes. Synthesis is the term chemists apply 
 to the former ; analysis to the latter mode of demonstrat- 
 ing its composition. 
 
 JVbidJ, it is most materially iinporfant, in connexion with 
 our future inquiries, to observe, that there are other matters, 
 not essential to the composition either of air or water, 
 that IN NATURE are always found mechanically mixed up or 
 associated with each, and this as an express provision for 
 the sustenance of animals and plants. 
 
 The atmosphere is not compounded purely of oxygen and 
 nitrogen ; it contains carbonic acid and watery vapour. The 
 proportion of carbonic acid in the atmosphere may be re- 
 garded as equal nearly to one part in a thousand, estimated 
 by weight. The quantity varies according to the seasons, 
 but the yearly average remains continually the same. 
 
 And the rain that descends from the clouds contains am^ 
 monia, one of the elements of which, as previously stated, 
 is nitrogen. Experiments confirm the theory upon which 
 
 4 
 
68 PRODUCTIVE FARMING. 
 
 the presence of ammonia in rain-water might reasonably 
 be expected. If a few hundred pounds of rain-water be 
 carefully subjected to distillation, and the first two or three 
 pounds evaporated, with the addition of a litlle muriatic 
 acid, a very distinct crystallization of muriate of ammonia, 
 or sal ammoinac, may be obtained, which crystals have a 
 brownish-yellow colour. If a little sulphuiic or muriatic 
 acid be added to a quantity of rain-water, and the mixture 
 boiled to dryness, tbe ammonia remains as the residue, in 
 combination with the acid employed ; and it may be detect- 
 ed by the addition of a litlle powdered lime, which, com- 
 bining with the acid, sets the ammonia free, and is recog- 
 nised by its pungent smell. The sensation which is per- 
 ceived upon moistening the hand with ra/Ti-water, so dif- 
 ferent from that produced by washing it in pure distilled 
 w-ater, and to which the term soft7iess is applied, is owing 
 to the presence of carbonate of ammonia in rain-water. 
 
 Hotv this ammonia is generated in rain-water, the im- 
 portance and utility of the fact, and the uses of carbonic 
 acid in the atmosphere, are matters so closely identified 
 with living processes in animals and plants, that we must 
 here simply confine ourselves to the statement. "We have 
 now the preliminary materials for the examination of nu- 
 tritive actions. When these, as they exist naturally, are 
 understood, we shall be able to say what are those substan- 
 ces called FERTILIZING, which may be useful in given instan- 
 ces as manure, whether their application may be suitable 
 or injurious ; just as a knowledge of anatomy and physi- 
 ology is necessary to the physician who would amend the 
 diseased conditions of the body. He must know what is 
 the nature of healthy and ordinary action in the living 
 frame, before he can understand and alter diseased action. 
 
 The artificial application oi water in large quantity to 
 the land, is a subject well understood, and its effects accu- 
 rately marked and recognised in many parts of the world 
 tliHt have been regarded as strictly agricultural localities 
 during a long succession of ages. Irrigation is, in truth, 
 a mode of applying the weakest of liquid manures, on a 
 
PRODUCTIVE FARMING. 69 
 
 very bold scale, to grass-lands. Almost every farmer has 
 a mode of accounting for the highly-fertilizing effects of 
 rigaiion. Davy added another to the list of explanations. 
 He thought that a winter-flooding protected the grass from 
 the injurious effects of the frost. He examined, with a 
 thermometer, and with his usual address, the water- mea- 
 dows near Hungerford, in Berkshire, and ascertained that 
 the temperature of the soil was ten degrees higher than the 
 surface of the water, and that, too, on a frosty March morn- 
 ing. He remarked, also, a fact that most farmers will 
 confirm, that those waters which breed the best fish are 
 ever the best fitted for watering meadows. 
 
 He appears, however, never to have steadily investigat- 
 ed the chemical composition of river-water with regard to 
 its uses in irrigation ; and in consequence, he knew little of 
 the value of some of its impurities to vegetation. Thus, if 
 the river-water contains gypsum, (sulphate of lime,) which 
 it certainly does if the water ishar'd, it must, under ordinary 
 circumstances, on this account alone, be highly fertilizing 
 to meadows, since the grasses contain this salt in very sen- 
 sible proportions. Calculating that one part of sulphate 
 of lime is contained in every two thousand parts of the 
 river-water, and that every square yard of dry meadow- 
 soil absorbs only eight gallons of water, then it will be 
 found, that by every flooding, more than one hundred weight 
 and a half of gypsum per acre is diffused through] the soil 
 in the water : a quantity equal to that generally adopted 
 by those who spread gypsum on their clover, lucern, and 
 sainfoin crops as a manure, either in a state of powder, or 
 as it exists in peat-ashes. 
 
 And, if we apply the same calculation to the organic 
 substances ever more or less contained in flood-waters, and 
 if we allow only 25 parts of animal and vegetable remains 
 to be present in a thousand parts of river-water, then we 
 shall find, taking the same data, that every soaking with 
 such water will add to the meadow nearly two tors per 
 acre of animal and vegetable matters ; which, allowing in 
 the case of water-meadows five floodings per annum, is 
 
60 PRODUCTIVE FARMING. 
 
 equal to a yearly application of ten tons of organic matter. 
 The quantity of foreign substances present in river-water, 
 although commonly less, yet very often exceeds the pro- 
 portion we have calculated to exist. 
 
 There is no stream more celebrated for its prolific water- 
 meadows than the Itchen in Hampshire ; and in no part 
 of Eno-land is the system of irrigation better understood and 
 more zealously followed. The water of this river, taken 
 from above the city of Winchester, contains in 10,000 
 parts, after all its mechanically suspended matters have 
 subsided, about 2.2-3d parts, namely — 
 
 Organic matter . . , . . 0.02 parts. 
 Carbonate of lime (chalk) . . .1.89 
 
 Sulphate of lime (gypsum) . . . 0.72 
 Muriate of Soda (common salt) . . 0.01 
 
 The water of lakes is usually still more surcharged with 
 foreign substances than those of rivers ; and, from the use 
 of such waters, especially if an occasional or winter stream 
 of water passes through them, we have witnessed great 
 fertilizing eff'ects produced on meadow land. 
 
 CHAPTER V. 
 
 Of the Nature of Vegetable Growth; thejtrue use of Vegetable 
 Mould or Humus ; and of the Sources of the Elementary Con- 
 stituents of Plants. 
 
 • From the facts detailed in the foregoing sections, the 
 development or nutrition and growth of a plant requires 
 the presence, first, of substances yielding carbon and nitro- 
 gen, as elements to the growing structure ; secondly, ot 
 water, furnishing in itself two very important elements, 
 namely oxyen and hydrogen, besides adventitious matters ; 
 and lastly, a soil, to yield the saline, earthy, metallic, or 
 other organic materials essential to vegetable life. 
 
RODUCTIVE FARMING. 61 
 
 The fertility of every soil is generally supposed to de- 
 pend on the presence in it of a peculiar substance, named 
 "Awmw.9." This substance, incorrectly supposed to form 
 the principal nutriment of plants, and to be extracted from 
 them by the soil in which they grow, is nothing more than 
 vegetable mouldy the product of the decay of other plants. 
 
 Adherence to the above incorrect opinion, has hith- 
 erto rendered it impossible for the true theory of the nutri- 
 tive process in vegetables to become known, and has thus 
 deprived us of our best guide to a rational practice in agri- 
 culture. Any great improvement in that most important 
 of all arts, is inconceivable without a deeper and more per- 
 fect acquaintance with the substances which really nourish 
 plants, and with the sources whence they are derived. It 
 was supposed that by the aid of water " humus" is rendered 
 capable of being absorbed by the roots of plants. If it be, 
 it must be in some altered Ibrm ; for if a portion of good 
 mould be long subjected to the action of water, that fluid 
 will not dissolve more than a hundred-thousandth part of 
 its weight, and contain only soluble organic matters, and 
 the salts which are contained in the rain-water which has 
 fallen upon it. Decayed oak wood, beech, and fir, yield 
 the same results. 
 
 Let us inquire whence the grass in a meadow, or the 
 wood in a forest, receives the carbon essential to the forma- 
 tion of that wooPY FIBRE Constituting the principal weight 
 and solid bulk of the tree or plant. Whole tracts of open 
 country in the green wilds of America, immense woods and 
 forests in all parts of the world, receive no carbon in the 
 form of manure ; how does it happen that the soil, instead 
 of being exhausted through the annual production of vege- 
 tation for ages, becomes every year richer in carbon ? In 
 other words, a certain quantity of carbon is taken every 
 year from an unmanured forest or meadow, in the form of 
 growing wood or grasses ; and in spite of this, the quantity 
 of carbon in the soil augments; it becomes richer in vege- 
 table mould, in humus — so much so, that in process of time 
 it will not support the trees which stood upon it : they fall, 
 
69 PRODUCTIVE FARMING. 
 
 and the surface becomes a peat-moss, burying huge trunks 
 in its bosom. Plants give back more carbon to the soil 
 than they take from it ; it is evident, then, that their growth 
 must depend on the reception of carbon as food from another 
 quarter. It is not denied that manure, rightly chosen 
 and applied, exerts an influence upon the growth of plants; 
 but it neither serves for the | roduclion of the carbonaceous 
 woody fibre, nor has any influence upon it, because we find 
 that the quantity of carbon produced by manured land is 
 not greater than that yielded by lands which are not ma- 
 nured. The discussion as to what manure really produces, 
 has nothing to do with the present question, which is, the 
 origin of the carbon as the principal element of the woody 
 fibre. It must be derived from other sources ; and as the 
 soil does not yield it, we are driven to look for it in the at- 
 mosphere. 
 
 Now% we have already stated that the air contains car- 
 bonic acid ; and if the reason of its presence there be not, 
 that it may yield carbon to plants, what other use can be 
 assigned to it ? Animals do not derive their chief suste- 
 nance from the air : to them pure and unmixed carbonic 
 acid is poisonous ; though taken into the stomach it is 
 grateful. Besides, we know it to be a fact, that during 
 the sunshine of day the leaves of plants are continually ab- 
 sorbing this very gas, and giving out oxygen; and if not 
 for their nutrition and growth, for what other purpose? 
 Carbonic acid being a compound of carbon and oxygen, 
 they retain the carbon and give out the oxygen. This has 
 been long known ; but it is only a recent discovery, that 
 the sole source of woody fibre is the atmosphere. 
 
 Mould, or humus, can only arise from the decay of 
 plants. No primitive mould can have existed ; for plants 
 must have preceded the mould, which this theory assumes 
 as necessary to their existence. Whence, then, did the 
 first vegetables derive their carbon, if not, as now, from the 
 surrounding air ? We shall arrive at satisfactory conclu- 
 sions respecting the mode in which animal, as w^ll as 
 vegetable, life and nutrition are maintained, by observing 
 
PRODUCTIVE FARMING. 63 
 
 how the uninterrupted uniformity of proportion is secured 
 in the quantities of the elements composing the atmosphere. 
 How does it happen that, with such an immense expendi- 
 ture of oxygen as occurs in the combustion of countless 
 millions of tons of coal, and in the consumption of that gas 
 in the lungs of the myriads of creatures that live on the 
 earth's surface, still the composition of the atmosphere is 
 invariably the same ? 
 
 The answer to this question depends upon another. 
 What becomes of the carbonic acid which is produced by 
 the breathing of animals, and in every instrmce where a 
 combustible body is burnt ? There is no change of volume ; 
 for the oxygen extracted from the atmosphere by a coal 
 fire is replaced by ihe same bulk of carbonic acid, and sim- 
 ilarly in every breath w^e draw. The immense masses of 
 carbonic acid which flow into the atmosphere from so many 
 causes ought perceptibly, after 6000 years, to increase its 
 quantity. 
 
 A cause must exist which prevents the increase of car- 
 bonic acid, by removing that which is continually forming; 
 and there must be some means of replacing the oxygen 
 which is removed from the air by combustion, breathing, 
 and putrefaction. 
 
 Both these causes are united and displayed in the 'pro- 
 cess of vegetable as well as of animal life. The facts we 
 have already stated prove that the woody fibre, or carbon 
 of plants, must be derived exclusively from the atmosphere. 
 Now, carbon exists in the air only in the form of carbonic 
 acid, and, therefore, in a state of combination with oxygen. 
 
 Besides, as already stated, carbon and the elements of 
 water form the principal constituents of vegetables. Now, 
 the proportion of oxygen in the whole mass of a plant is 
 less than in carbonic acid. It is, therefore, certain that 
 plants must possess the power of decomposing carbonic 
 acid, since they appropriate the carbon for their own use. 
 The formation of woody fibre, gum, starch, and the various 
 substances containing carbon — that taken together com- 
 pose a plant — must necessarily be attended wuth the sepa' 
 ration of the carbon of the carbonic acid in the air from 
 
64 PRODUCTIVE FARMING. 
 
 the oxygen of that acid. This oxygen is returned to the 
 atmosphere, as experiment and observation prove, though 
 its source is only just understood. And the carbon enters 
 into composition with water, or its elements in the plant. 
 The atmosphere must thus receive a volume of oxygen for 
 every volume of carbonic acid which has been abstracted 
 from it and decomposed. The leaves and green parts of a 
 plant emit an equal quantity of oxygen in exchange for the 
 carbonic acid they absorb, and they will do this even when 
 torn from the stem on which they were just growing. 
 Each acre of land which produces eight hundred weight 
 of carbon, (say woody fibre,) gives annually to the atmos- 
 phere about two thousand six hundred pounds of free oxy- 
 gen gas ; so that an acre of meadow, wood, or cultivated 
 land, replaces, therefore, in the atmosphere as much oxy- 
 gen as is exhausted by eight hundred weight of carbon, 
 either in its ordinary destruction by burning, or in the ac- 
 tion of the lungs of animals. 
 
 Plants not only separate all noxious matters from the 
 air, — they form, by this arrangement, an inexhaustible 
 source of pure oxygen to supply that loss the air is con- 
 stantly sustaining. Animals, on the other hand, throw off 
 carbon from their lungs, which plants take in by their 
 leaves ; and thus the composition, or the relative propor- 
 tions of the elements forming that medium in which they 
 both exist, is maintained constantly unchanged. 
 
 Many conditions are necessary for the life and growth 
 of plants. Each kind requires special conditions; and 
 should but one of these be wanting, although all the rest 
 be supplied, the plants will not be brought to maturity. 
 It is in vegetable as in animal life : a mother crams her 
 child exclusively with arrow-root; it becomes fat, it is 
 true ; but alas ! it is rickety, and gets its teeth very slow- 
 ly and with difficulty. Mamma is ignorant, or never thinks 
 that her offspring cannot make bone, or, what is the same 
 thing, phosphate of lime, the principal bulk of bone, out 
 of starch. It does its best ; and were it not for a little 
 milk and bread, perhaps now and then a little meat and 
 soup, it would have no bones and no teeth at all Farmers 
 
PRODUt:TlVE FARMING. 65 
 
 keep foultry ; and what is true of fowls, is true of a cab- 
 bage, a turnip, or an ear of wheat. If we mix with the 
 food of fowls a sufficient quantity of egg-shells, or chalk, 
 which they eat greedily, they will lay many more eggs 
 than before. A well-fed fowl is disposed to lay a vast 
 number of eggs; but cannot do so without the materials 
 for the shells, however nourishing in other respects her 
 food may be. A fowl, with the best will in the world, not 
 finding any lime in the soil, nor mortar from walls, nor 
 calcareous matter in her food, is incapacitated from laying 
 any eggs at all. Let farmers lay such facts as these, which 
 are matter of common observation, to heart, and transfer 
 the analogy, as they justly may do, to the habits of plants, 
 which are as truly alive, and answer as closely to evil or 
 judicious treatment as their own horses. The organs of 
 plants, like those of animals, contain substances of the 
 most different kinds. Some are formed solely of carbon 
 and the elements of water : as, for instance, woody fibre, 
 resin, gum, and starch; some contain nitrogen : as, for in- 
 stance, the gluten of wheat ; and in all plants we find me- 
 tals in a state of combination with oxygen. The food 
 which can serve for the production or increase of any, or of 
 all the organs of a plant, must necessarily contain the ele- 
 ments of that part, or set of parts. Dogs die although fed 
 with jelly, which contains nitrogen in abundance : they 
 cannot live upon white bread, sugar, or starch, if these 
 are given as food, to the exclusion of other substances. 
 Can it be concluded from this, that these things contain no 
 elements suited for nutrition 1 Certainly not. 
 
 Because a vegetable is alive, it has the power of con- 
 stantly reproducing itself; for this it requires a supply of 
 substances which contain the constituent elements of its 
 own substance, and which are susceptible of undergoing 
 the necessary transformation. All the organs together, 
 whether of animal or vegetable life, have not the power to 
 generate, that is, to produce out of nothing a single ele- 
 ment. A dog would die in the vacuum of an air-pump, 
 even though supplied with a superabundance of food ; it 
 
 4* 
 
66 PRODUCTIVE FARMING. 
 
 will die in the air if no food be given to it ; it will die in 
 oxygen gas, however freely it may be supplied with nour- 
 ishment. But it is not hence to be concluded, that neither 
 flesh, nor air, nor oxygen, is fitted to support life. They 
 are all admirably calculated to do so; so it is just as rea- 
 sonable to expect to bring a plant to perfection, — wheat, 
 for instance, — which, in its healthy and natural state, con- 
 tains silica, or potash, if it be planted in a soil destitute of 
 such inorganic materials, or to which they have not been 
 added. When we are acquainted with the nature of 
 a single cubic inch of that soil, and know the composition 
 of air and rain-water, we are in possession of all the con- 
 ditions necessary to their life. The source of the different 
 elements entering into the composition of plants, cannot 
 possibly escape us, if we know in what form they take 
 up their nourishment, and compare its composition with 
 that of the vegetable substances which compose their 
 structure. 
 
 Vegetables undergo, after death, two processes of decom- 
 position : one of these is for mentation, the other is putre- 
 faction. Decaying leaves, stalks, or roots, are, in fact, 
 undergoing a slow process, analogous to combustion ; inas- 
 much as it is the combination of the combustible parts of a 
 plant, (structures that will burn,) with the oxygen of the 
 atmosphere. 
 
 The decay of woody fibre (the principal constituent 
 of all plants) is accompanied by appearances of a peculiar 
 kind. This substance, in contact with air or oxygen gas, 
 and no longer preserved from chemical decomposition by 
 the living principle which has now left it, unites with that 
 gas, and the product is an equal volume of carbonic acid. 
 The property which woody fibre in a state of decay has to 
 form carbonic acid with the surrounding oxygen of the 
 atmosphere, diminishes as the decay advances, till it is com- 
 plete, and ceases. Mould constitutes the principal part of 
 brown coal and peat. An atmosphere of carbonic acid, 
 formed at the expense of the oxygen of the air, surrounds 
 every particle of decaying vegetable matter ; hence the 
 
PRODUCTIVE FARMINO. ^ 
 
 value of ploughing, digging, and otherwise loosening the 
 soil : it permits the access of air. An atmosphere of car- 
 bonic acid is therefore contained in every fertile soil, and is 
 the first and most important food for the young plants before 
 they reach the surface. The leaves of trees which fall ia 
 the forest in autumn, and old roots of grass in a meadow, 
 are converted into what is termed humus by the same 
 a2;ency ; but humus does not nourish plants directly, by 
 be ng taken up in its unaltered state, but by presenting a 
 slow and lasting source of carbonic acid, which is absorbed 
 by the roots of plants, and forms their principal nutriment 
 at a time when, being destitute of leaves, they cannot, as 
 yet, extract food from the atmosphere : hence one reason 
 of the value of ploughing, digging, and otherwise lightening^ 
 the soil, by permitting the access of air, and consequently, 
 of carbonic acid to the seeds and roots. Seeds should 
 always be sown, so as to be fully exposed to the influence 
 of the air ; and one cause of the unproductiveness of cold, 
 clayey, adhesive soils is, that the seed is coated with matter 
 which the air cannot get at. In sandy soils, the earth is 
 mostly sufficiently penetrable by the atmosphere ; but in 
 clayey soils, there can scarcely be too great a mechanical 
 tearing up and division, in the process of tillage. Many 
 ploughmen know the fact, without knowing the reason of 
 it : however, any seed not fully supplied with air, always 
 produces a weak and diseased plant. In this way, ihen, 
 we see the true uses of the vegetable decaying mould, whea 
 well torn up by the plough. The roots perform the after- 
 functions of the leaves : they extract from the soil the car- 
 bonic acid generated from the humus, or vegetable mould j 
 they decompose that acid, and absorb the carbon. Whea 
 a plant is quite matured, and when the organs by which it 
 obtains food from the air are fully formed, the carbonic acid 
 of the soil is no longer required. 
 
 If turnips be sown in a soil capable of yielding as much 
 nourishment as they will take up, they Avill attain a much 
 larger size than under the reverse circumstances. The 
 size of a plant is always proportioned to the sukface of the 
 
68 PRODUCTIVE FARMING. 
 
 organs which are destined to convey food to it. A plant 
 gains another mouth and stomach with every new fibre of 
 root, and every new leaf. 
 
 Let us suppose a plant fully grown. All the necessary 
 amount of woody fibre has been formed by the leaves. 
 But the action of the leaf does not cease. Carbon is 
 still absorbed ; the expenditure of nutriment, the supply 
 of which continues the same, takes a new direction. The 
 leaves now produce sugar, starch, gum, or acids, which 
 were previously formed by the roots when these substances 
 were necessary for the development of the stem, buds, 
 leaves, and branches of the rising plant. The direction of 
 the nutriment again changes, and blossoms are produced. 
 The functions of most plants cease upon the ripening of 
 their fruit, because the products of their action are no 
 longer needed. They now yield to the chemical influence 
 of the oxygen of the air : their feeble vitality weakly op- 
 poses the decomposition which awaits all dead matter ; 
 they change colour, fall off, and become converted into the 
 mould of which we have been speaking. 
 
 A cubic inch of sulphuretted hydrogen gas introduced 
 intp the human lungs would cause instant death ; but it is 
 often formed, under a variety of circumstances, in the 
 bowels without injurious effects. Each organ, whether of 
 an animal or a vegetable, extracts from the food presented 
 to it what it requires for its own action and sustenance ; 
 while the remaining absorbed matters, which are not nutri- 
 tive, combine together, and are separated as excrement. 
 The excrementitious matters of one organ come in contact 
 with another during their passage through the plant or 
 animal, and, in consequence, suffer 7iew transformations : 
 the useless matters rejected by one organ contain the ele- 
 ments for the nourishment of another, till what is utterly 
 useless is expelled from the system, by contrivances for 
 that purpose. So the kidneys, liver, and lungs, are organs 
 of excretion : the first separate from the body substances 
 in which a large proportion of nitrogen is contained ; the 
 second those with an excess of carbon ; and the third, such 
 
PRODUCTIVE FARMING. 69 
 
 as are composed, principally, of more oxygen and hydrogen 
 than is wanted. All superabundant nitrogen is thrown 
 out from the body as a liquid excrement through the uri- 
 nary passages ; all solid substances, incapable of further 
 useful transformation, pass out by the intestinal canal ; and 
 all gaseous matters by the lungs. 
 
 The presence of life prevents common chemical decom- 
 position or putrefaction : the power to effect the trans- 
 formations essential to nutrition and growth does not be- 
 long to it. Each such transformation is owing to a dis- 
 turbance in the attraction of the elements of a given com- 
 pound, and is, consequently, a purely chemical process. 
 Similar changes of existing compounds are in constant pro- 
 gress during the whole life of a plant ; in consequence of 
 which there are produced gaseous matters, thrown off by 
 the leaves and blossoms, sohd excrements deposited in the 
 bark, and fluid soluble substances which are excreted by 
 the roots. Through the expulsion of these matters unfitted 
 for nutrition, the soil receives back again the greatest part 
 of the carbon, which it had at first yielded to the young 
 plants as food in the shape of carbonic acid, from the de- 
 caying mould. 
 
 Having disposed of the question as to the origin of 
 carbon in plants, and examined the relation between vege- 
 table mould and the springing vegetable, we must next 
 trace the source of the hydrogen and nitrogen they contain. 
 
 All the hydrogen necessary for the formation of a plant 
 or animal is supplied by the decomposition of water. From 
 their generating wax, fats, and volatile oils, containing 
 hydrogen in large quantity, and no oxygen, we may be 
 certain that plants possess the property of decomposing 
 water ; because from no other body with which they are 
 placed in contact, could they obtain the hydrogen which 
 exists as an element in those matters. The process ofvege- 
 table growth, in its simplest form, consists in the extraction 
 of hydrogen from water, and carbon from carbonic acid. 
 The green resinous principle of the leaf diminishes in 
 quantity while oxygen is absorbed. We can explain, in a 
 
70 PRODUCTIVE FARMING. 
 
 similar manner, the formation of all the component sub- 
 stances of plants which contain no nitrogen. During the 
 progress of growth, plants appropriate carbon from the car- 
 bonic acid found in the air, and hydrogen from the decom- 
 position of water ; the oxygen of which fluid is set at liberty, 
 together with a part, or all of that contained in the carbonic 
 acid. Decay, then, or vegetable putrefaction, is that great 
 operation of Nature by w^hich that oxyen which was con- 
 sumed by plants during life is again returned to the atmos- 
 phere ; for water is essential to such putrefaction. 
 
 As to the origin of nitrogen in plants, we may observe, 
 that it exists in every part of the vegetable structure. No 
 plant would attain maturity, even in the richest vegetable 
 mould, unless nitrogen were supplied to it. How, it may 
 be asked then, and in what form, does Nature furnish nitro- 
 gen to assist in the formation of vegetable albumen and 
 gluten, to fruits and seeds ? 
 
 This question is susceptible of a very simple solution. 
 Plants, as we know% grow perfectly well in pure charcoal, 
 if supplied at the same time — not with river or spring, or 
 perfectly pure water, but with ram-water. Now% rain- 
 w-ater can contain nitrogen only in two forms — either as 
 dissolved atmospheric air, (which, of course, contains nitro- 
 gen,) or as AMMONIA, of w'hich nitrogen is one element. 
 We have observed, in speaking of the composition of water, 
 that ram-water is found to contain ammonia ; and this is 
 the practical application of the fact. Pure air may, for 
 our present purpose, be considered as oxygen and nitrogen 
 in certain unalterable proportions, in a state of mixture ; 
 the carbonic acid and ammonia which float in the atmos- 
 phere may be regarded as accidental ingredients. If we 
 were to suppose that plants derived their nitrogen directly 
 from the atmosphere, — that is, by depriving the air of a 
 portion of that nitrogen which is essential to its constitution 
 — we are met by many difficulties. Rain-water does not 
 yield nitrogen from pure air, which it may hold in solution 
 or suspension, but from ammonia, which, rising from putre- 
 fied animal remains, becomes readily dissolved in the first 
 
PRODUCTIVE FARMING. 71 
 
 mass of watery vapour that may present itself. We have 
 no reason to believe that the nitrogen of the air takes part 
 in the processes of nutrition in plants and animals ; on the 
 contrary, we know that many veg«^tables emit, or give off 
 the nitrogen which is absorbed by their roots. But, on the 
 other hand, there are numerous facts, showing that the 
 formation in plants of substances containing nitrogen, as 
 gluten, for instance, in corn, takes place in proportion to the 
 quantity of this element, which is conveyed to their roots 
 in the state of soluble salts of ammonia, derived from the 
 putrefaction of animal matter. 
 
 All animal bodies, during their decay, yield the nitrogen, 
 which they abundantly contain, to the atmosphere in the 
 form of ammonia. A generation of a thousand millions of 
 human beings is renewed every thirty years : countless 
 millions of animals have, during that period, ceased to live. 
 Where, but floating in the atmosphere, is the nitrogen 
 their bodies contained during life ? Without the occurrence 
 ofi^utridity and the g;eneration of ammonia, and its diffusion 
 in the air, the wheels of nature would soon stop — vegetable 
 and animal life could go on no longer. Ammonia is the 
 simplest of all the compounds of nitrogen : the reader will 
 remember our previous statement, that hydrogen and nitro- 
 gen combine to form ammonia. Hydrogen is that element 
 for which nitrogen possesses the most powerful affinity. 
 
 The nitrogen, then, of putrefied animals is contain- 
 ed in the atmosphere (combined with hydrogen) as 
 ammonia, in the form of a gas which is capable of enter- 
 ing into combination with carbonic acid, and of forming a 
 volatile salt very soluble in water. Ammonia, therefore, 
 cannot remain long in the air, as every shower of rain must 
 dissolve it and convey it to the earth's surface, to be ab- 
 sorbed and decomposed by the roots of plants. We ought 
 to expect, and such is the fact, that ram-water must at all 
 times contain ammonia, though not always in equal quan* 
 tity. If a pint of rain-water contain only a quarter of a 
 grain of ammonia, then a field of forty thousand square 
 feet must receive yearly upwards of eighty pounds of am- 
 
72 PRODUCTIVE FARMING. 
 
 monia, or sixty-five pounds of nitrogen; for it is ascertained 
 that the annual fall of rain-v^rater over this extent of surface 
 is at least 2,500,000 pounds. This is much more nitrogen 
 than is contained in the form of vegetable albumen and 
 gluten in 2650 pounds of wood, 2800 pounds of hay, or 
 200 cwt. of beet-root, which would be the yearly produce 
 of such a field ; but it is less than the strawy roots, and grain 
 of corn which might grow on the same surface would con- 
 tain. Animal manure, as we shall presently show, acts 
 only by the formation of ammonia. Its employment in the 
 cultivation of grain, and of fodder for cattle, furnishes con- 
 vincing proof that the nitrogen of vegetables is derived 
 from ammonia. The quantity of gluten in wheat, rye, and 
 barley, is very different; and they contain nitrogen in vary- 
 ing proportions. Even in samples of the same seed the 
 quantity varies ; and why ? Evidently because one variety 
 has been better fed with its own appropriate fertilizer, than 
 another which has been reared on a soil less accurately 
 adapted by artificial means for its growth. French wheat 
 contains 12 per cent, of gluten ; Bavarian 24 per cent. 
 Sir H. Davy obtained 19 per cent, from winter, and 24 
 from summer wheat; from Sicilian 21, from Barbary 
 wheat 19 per cent. Such great differences must be 
 
 OWING TO SOME CAUSE, AND THIS WE FIND IN THE DIFFER- 
 ENT METHODS OF CULTIVATION. An increase of animal 
 manure gives rise not only to an increase in the number 
 of seeds, but also to a remarkable difference in the pro- 
 portion of gluten which those seeds contain. Among 
 manures of animal origin there is great diversity. Cow 
 dung contains but a small proportion of nitrogen. One 
 hundred parts of wheat, grown on a soil to which this 
 material was applied, afforded only 11 parts of gluten, and 
 64 of starch ; while the same quantity of wheat, grown on 
 a soil fertilized with human urine, yielded 35 per cent, of 
 gluten, and of course a smaller proportion of less valuable 
 ingredients. During the putrefaction of urine, ammoniac- 
 al salts are formed in large quantity, it may be said, exclu- 
 sively ; for under the influence of warmth and moisture, 
 
PRODUCTIVE FARMING. 73 
 
 urea, the most prominent ingredient of urine, is converted 
 into carbonate of ammonia. Putrid urine is employed in 
 Flanders as a manure with the best results. The barren 
 soil on the coast of Peru is rendered fertile by means of a 
 manure called Guano, which is collected from several 
 islands in the South Sea. It forms a layer several feet in 
 thickness upon the surface of these islands, and consists of 
 the putrid excrements of innumerable sea-fowl that remain 
 on them during the breeding season. This substance has 
 recently been imported in large quantities into England ; 
 and its fertilizing powers are very extraordinary. Its price, 
 about <£18 per ton, is a serious objection; and since the 
 nitrogen it contains forms its principal recommendation, 
 doubtlessly other matters nearer home will not be wasted, 
 or their value unknown and disregarded, as to a great ex- 
 tent they have been. As to the practical results of the 
 application of Guano, an intelligent agriculturist in the 
 neighbourhood of Hamburg has forwarded the annexed 
 remarks to the Editor of the Gardener^s Chrcnide. He 
 observes that " Most of the experiments with guano in the 
 vicinity of this city have been made on meadows and 
 lawns. On these it has produced the best possible effects ; 
 so that, for instance, at Flottbeck, the patches manured 
 with guano presented not only a finer and darker green, 
 but the grass was closer and more rich ; so that, comparing 
 it with patches not guanized, the produce of the former 
 may, without exaggeration, be stated to be double. To 
 give an idea of the extraordinary forcing qualities of gua- 
 no, we may mention that at Flottbeck, on a spot of grass 
 managed after the English fashion, the second cutting of 
 the grass was necessarily five days after the first, while the 
 grass growing close by, (which had not been guanized,) 
 although healthy and vigorous, required double the time to 
 arrive at the same state of progress. It deserves to be 
 stated as something remarkable, that on the guanized spot, 
 the dew^ appeared in the morning much stronger on the 
 tops of the leaves, than on the part unguanized. In an 
 experiment made by M. Staudinger on a barren hill, com- 
 
74 PRODUCTIVE FARMING. 
 
 pnsed of granite or quartz, the guanized spot exhibited a 
 dark bluish green sward, while round about nothing but 
 barrenness was to be seen. If, therefore, a land owner 
 wisht'Sto cover bleak hungry pasture in a short time with 
 nutritious grass for cattle or sheep, the guano certainly is 
 the thing to do it. It would not only produce a plentiful 
 fodiler in the autumn, where cattle can be well nourished and 
 prepared for the winter, but such guanized pasture will bring 
 a heavy crop early in the spring. Guano has also been 
 used advantageously on a sour meadow overgrown with 
 horsetails; and it produced, instead of reeds and bullrushes, 
 a dense turf of sweet grass, and the horsetail almost dis- 
 appeared. Thus, in the first place, more grass is ob- 
 tained, which may be put down as double the former 
 crops ; and then the grass is very much improved in quality. 
 Of course good drainage must be attended to on each mea- 
 dow, if the result is expected to be complete. In using 
 guano we must be careful to pulverize it well ; because, on 
 account of its tenacity, it will form into lumps, and on 
 places where it lies too thick, it will burn the grass, although, 
 subsequently, even on such places a luxuriant herbage will 
 spring up. Experiments with guano on spring crops have 
 been as successful at Flottbeck, with both wheat and rye, 
 as on the above meadow. The wheat manured in the 
 spring with guano is much superior to that manured in the 
 ordinary way, both in grain and straw. The following 
 experiment was tried on a spot of almost blowing sand : — 
 * On the iSth March, several square rods in the above lo- 
 cality, planted with winter rye, were strewed with guano. 
 The spot thus manured was in a short time not only con- 
 spicuous for its dark green colour, but the tiller became so 
 luxuriant as to cover the whole surface. Notwithstanding 
 a drought of two months, the guanized crops remained in 
 the same flourishing condition ; whilst the other rye standing 
 close by had a weak and sickly appearance. Subsequently 
 the former attained the height of five or six feet, with ears 
 five inches long, with strong plump grain ; whilst the latter 
 were scarcely half that height in straw, and their ears were 
 
PRODUCTIVE FARMING. 75 
 
 barren and empty.' This experiment speaks in favour of 
 guano in preference toother manure in another respect. If a 
 light sandy soil like the above is manured too much wilh 
 common dung, and if there follows a luxuriant vegetation, 
 •with dark green foilage, we may be sure that, if there be 
 subsequently any long drought, or sudden change of temper- 
 ature from great heat to intense cold, rust will follow as a 
 matter of course; whilst, in the above experiment, not- 
 withstanding a nine-weeks' drought, and some intervening 
 night frosts, the growth of the guanized rye was uniformly 
 good up to the ripening of grain — a sufficient proof that 
 the guano must possess the property of attracting and re- 
 tainmg the fine vapour contained in the air. Hence the 
 fact is to be explained why dew was more apparent on the 
 guanized turf than on that not subjected to that process. 
 As we know that, in general, during long drought, the ac- 
 tion of dung — in fact of every manure — ceases; and as it 
 is light sandy soil which first suffers from drought, it must 
 be eviilent what valuable manure guano is, not only on 
 pastures, but for winter rye, our chief crop on light land. 
 If an acre of land is dressed with 125 lbs. of guano, an 
 abundant crop of grain and straw will fully repay the ex- 
 penses incurred. If such a rye-field is laid down in spring 
 with meadow catstail grass {Plileum pratense) and while 
 clover, a heavy grass crop in the autumn would still increase 
 the advantages already mentioned. As rape can by no 
 means be too luxuriant, guano would produce an extraor- 
 dinary result on it." 
 
 If a soil consist only of sand and clay, and be deficient 
 of organic matter or the decaying remnants of animal or 
 vegetable life, it is sufficient, and chemically correct, to add 
 to it guano, in order to ensure a plentiful crop. Guano con- 
 sists of ammonia in separate combination with uric, })hos- 
 phoric, oxalic, and carbonic acids, together with a few earthy 
 salts and some impurities. If guano be the fertilizer em- 
 ployed, it is valuable, chiefly from the ammonia it contains, 
 anil ammonia is valuable because one of its elements is 
 nitrogen, which is yielded to the plants. Ammonia assists 
 
76 PRODUCTIVE FARMING. 
 
 not only in the formation of gluten in wheat, but also in 
 the production of vegetable albumen, one of the principal 
 constituents of plants, and it is ammonia which forms the 
 red and blue colouring of flowers. Nitrates, that is, earthy 
 or metallic substances, combined with nitric acid, (which 
 nitric acid is itself a comj)ound of nitrogen and oxygen,) 
 are necessary constituents of several plants which thrive 
 only when ammonia is present, — hence the value of nitrate 
 of soda. The influence of the dried rays of the sun is to 
 effect the disengagement of oxygen from the stem and 
 leaves of plants, (as previously stated,) which oxygen, 
 seizing upon the nitrogen contained in ammoniacal mat- 
 ters, forms nitric acid, found in union with certain bases in 
 many vegetables. In this way ammonia, by its transform- 
 ation, furnishes nitric acid to the tobacco plant, that is, if 
 it be found growing in a soil completely free from nitre or 
 saltpetre, which is not nitrate of soda, but, in chemical lan- 
 guage, nitrate of potass. The urine of men and of ani- 
 mals living upon flesh contains a large quantity of nitro- 
 gen, partly in the form of phosphates, partly as tirea, a 
 substance naturally peculiar to urine. Urea is transformed 
 by the putrefactive process into carbonate of ammonia ; 
 that is to say, it takes the form of the identical salt which 
 is always present in rain-water. Human urine is the most 
 'powerful manure for all vegetables which contain nitrogen ; 
 that of horses and horned cattle contains less of this ele- 
 ment^ hut infnitely more than the solid excrements of these 
 animals. 
 
 In the face of such facts as these, is it not pitiable to 
 observe how the urine of the stable or cowshed is of en 
 permitted to run off", to sink uselessly into the earth, or to 
 form a pool in the middle of a farm-yard, from which, as 
 it putrefies, the ammonia formed in it is rapidly and com- 
 pletely escaping into the atmosphere, to be of as great 
 utility in that volatile form to a neighbour's acres as to those 
 nearer home ? 
 
 It should be the care of the farmer so to employ all the 
 substances containing nitrogen which his farm affords in 
 
PRODUCTIVE FARMING. 77 
 
 the shape of animal excrements, that they shall serve as 
 nutriment to his own fields. This will not be the case 
 unless they are properly preserved and distributed over the 
 soil. A heap of manure lying unemployed would serve 
 him no more than other people, if the nitrogen it contains 
 be allowed to form ammonia, by combining with hydrogen. 
 All animal matters emit carbonic acid and ammonia aslong 
 as any nitrogen remains in them. The residue is a nearly 
 worthless carbonaceous mass. All animal excrements 
 emit carbonic acid and ammonia as long as nitrogen exists 
 in them. In every stage of their putrefaction an escape of 
 ammonia from them may be induced by moistening them 
 with pearl-ashes dissolved in water, the ammonia being 
 apparent to the senses by its pungent effect on the nostrils. 
 This ammonia evolved from manure is imbibed by the soil 
 either in solution in water, or in the form of gas ; and thus it 
 is that plants may artificially be made to receive a larger 
 supply of nitrogen than is naturally afforded to them by 
 the surrounding atmosphere. Cultivated plants receive, of 
 course, the same quantity of nitrogen from the air as trees, 
 shrubs, and wild plants ; but this, of course, is not enough 
 for the purposes of agriculture ; cabbages, wheat, potatoes, 
 and apples being very different things in their wild, or, more 
 properly, their natural state. The object of forest culture 
 is, the production of carbon or woody fibre ; of garden or 
 field culture, chiefly the addition of as much nitrogen as 
 the plant can be made to take up. 
 
 The solid excrements of animals do not contain as much 
 nitrogen as those which are voided in a liquid form ; and, 
 for this reason, do not constitute so powerful a fertilizing 
 material. This could not be otherwise. The quantity of 
 food which animals take, diminishes or increases in pro- 
 portion as it contains more or less of the substances con- 
 taining nitrogen. The bowels of the cow are relatively 
 much longer than those of the tiger ; the bulk of food 
 consumed by the former animal is greater, and it requires 
 to be retained longer, to traverse a greater extent of 
 surface, before it can yield all its nutriment, than occurs in 
 
78 PRODUCTIVE FARMING. 
 
 animals feeding on flesh, which contains so much nitrogen. 
 A horse may be kept alive upon potatoes, which contain 
 very little nitroc^en ; but life thus supported is gradual 
 starvation. So the quantity of rice which an inhabitant of 
 the East Indies will eat astonishes an Englishman ; but 
 the fact that rice contains less nitrogen than any other 
 kind of grain, at once explains the circumstance. In hot 
 countries human beings live sparingly on vegetables which 
 contain little of this principle ; in very cold countries, 
 human beings require very fat substances, in order to sup- 
 port existence, and to enable them to generate as much 
 animal heat as is necessary. The Esquimaux will devour 
 amazing quantities of whale's blubber, and would speedily 
 die (in that climate) without a free supply of food con- 
 taining large quantities of nitrogen. Hence, vegetation is 
 scanty — for food it is scarcely necessary : they live upon fish, 
 or animals caught in the chase. In tropical climates, on 
 the contrary, where animal food is not so necessary, a 
 luxuriant vegetation is provided to satisfy the natural 
 wants of man. 
 
 By means of manure an addition only is made to the 
 nourishment supplied from the air ; for the excrements of 
 all animals contain less nitrogen than their food, and conse- 
 quently a smaller quantity of matter containing nitrogen is 
 given to the soil than has been abstracted in the form of 
 grass, hay, or seeds. 
 
 Another reason why liquid excrements containing am- 
 monia (or that which, by further spontaneous chemical 
 action yields ammonia, and consequently nitrogen) are 
 more useful than solid excrements, is to be found in the 
 fact, that the former contain the greatest part of their am- 
 monia in the state of salts : in a form, therefore, in which 
 it has lost its volatility when presented in this condition, 
 not the smallest quantity of ammonia, in such a shape, is 
 lost to the 'plants, — it is all dissolved by water and imbibed 
 by their roots. Practical farmers see the results : they 
 know that plaster of Paris or gypsum, the insoluble sul- 
 phate of lime, strikingly increases the luxuriance of meadow 
 
PRODUCTIVE FARMING. 79 
 
 grass upon which it is strewed. But why ? Because it 
 fixes in the soil all the ammonia of the atmosphere, which 
 would otherwise be 'partially volatilized with the water 
 that constantly evaporates from the surface of the soil. 
 The sulphuric acid of the sulphate of lime has a stronger 
 affinity for ammonia than it has for lime ; so sulphate of 
 ammonia is formed, which is not volatile, does not escape 
 into a neighbour's pastures. In such an instance, the 
 carbonate of ammonia naturally contained in rain-water is 
 decomposed by the gypsum, in precisely the same manner 
 as occurs in the manufacture of sal-ammoniac. Soluble 
 (but not volatile) sulphate of ammonia, and carbonate of 
 lime or chalk, are formed by double decomposition ; so 
 that the beneficial eflfects of gypsum as a manure are not 
 direct, but indirect, hy fixing the ammonia either of rain- 
 water or of manure with which it may have been mixed, 
 and thus presenting that ammonia, or its valuable element 
 nitrogen, to the roots of plants in a form susceptible of 
 absorption. All the gypsum gradually disappeais, but its 
 action upon the carbonate of ammonia continues as long as 
 a trace of it exists. 
 
 It is quite evident, therefore, that science alone can 
 truly explain the mode in which certain matters exert their 
 beneficial agency ; and consequently science alone can ra- 
 tionally direct the practical farmer. All else beside is 
 mere experiment,— hazardous, expensive, and conjectural. 
 
 In order to form an idea of the effect of gypsum, it may 
 be sufficient to remark, that ICO pounds of burnt gypsum 
 fixes as much ammonia in the soil as 6250 pounds of horses' 
 urine would yield to it. The decomposition of gypsum 
 does not take place instantaneously ; it proceeds very grad- 
 ually, and this explains why the action of gypsum lasts for 
 several years ; the supply of ammonia from the air, of course, 
 remaining steady and unfailing. 
 
 All rust of iron (or iron in combination with oxygen) 
 contains a certain quantity of ammonia : the advantage of 
 manuring fields with burned clay depends upon the presence 
 of oxide of iron. Now, all minerals containing alumina, 
 
80 
 
 PRODUCTIVE FARMING. 
 
 or oxide of iron, possess, in a remarkable degree, the pro- 
 perty of attracting ammonia from the atmosphere, and of 
 retaining it in the soil. Pipe-clay, (which is aluminous 
 earth,) when moistened with a solution of caustic potash, 
 emits ammonia, which it has absorbed from the atmosphere 
 Soils, therefore, containing oxides of iron, and burnt clay, 
 must absorb ammonia, which is separated by every shower 
 of rain, and conveyed, in a dissolved state, to the roots of 
 vegetables. Charcoal possesses a similar action ; it will 
 absorb ninety times its volume of ammoniacal gas, which 
 may again be separated simply by moistening it with water, 
 in which ammonia is extremely soluble. This explains 
 why plants will grow in pure charcoal moistened with 
 RAiN-water. We have here another easy and satisfactory 
 method of explaining still further the properties of humus, 
 or of wood in a decaying state. Decayed oak-w^ood ab- 
 sorbs 72 times its w^eight of ammonia ; humus, then, is not 
 only a slow and constant source of carbonic acid, (repair- 
 ing the loss of that which is constantly decomposed and 
 absorbed by the leaves of vegetables, as before stated,) but 
 it is a means by which the necessary nitrogen is mechani- 
 cally conveyed to plants. 
 
 No conclusion can have a better foundation than this, 
 that it is the ammonia of the atmosphere which furnishes 
 all the nitrogen to plants they receive while uncultivated. 
 All the innumerable products of vitality resume, after death, 
 the original form from which they sprung ; and thus death, 
 the complete dissolution of an existing generation of ani- 
 mals and plants, becomes the source of life for a new one, 
 and of that artificial 7ir\A forced amount of nutriment which 
 plants may be compelled to receive, if judiciously fed, or, 
 in other words, manured. 
 
CHAPTER VI. 
 
 Of the Sources of the Saline, Earthy, and other Unorganized 
 Constituents of Vegetables. 
 
 A further question arises : Are the conditions already 
 considered all that is necessary for the life and growth of 
 plants ? It will now be shown that they are not. 
 
 Carbonic acid, water, and ammonia, are necessary for 
 the existence of vegetation, because they contain the e/c- 
 ments from which their organs are formed ; but other sub- 
 stances are requisite (as silica in straw) for the formation 
 of certain organs destined for special functions peculiar to 
 each family of plants. Plants obtain these substances from 
 inorganic nature. In the ashes of burnt vegetables the same 
 substances are found, although in an altered condition. — 
 Many of these inorganic constituents vary according to the. 
 soil in which the plants grow ; but without a certain num- 
 ber of them, according to the nature of such plant, they 
 never arrive at maturity. All substances that water will 
 dissolve in a soil are absorbed by the roots of plants ex- 
 actly as a sponge imbibes a liquid indiscriminately. The 
 substances thus conveyed to plants, are either retained in 
 greater or less quantity, or are entirely separated when not 
 suited for nutritive purposes. 
 
 Phosphate of magnesia^ in combination with ammonia, 
 is an invariable constituent of the seeds of all kinds of 
 grasses. It is contained in the outer husk, and is intro- 
 duced into bread, along with the flour, as part of the bran. 
 When ammonia is mixed with beer, this salt is precipi- 
 tated. 
 
 Most plants contain acids of very different composition 
 and properties, all of which are in combination with bases, 
 such as potash, soda, lime, or magnesia. These bases evi- 
 dently regulate the formation of the acids; for example, the 
 
 5 
 
82 PRODUCTIVE FARMING. 
 
 quantity of potash contained in the juice of the grape is 
 less when it is ripe than when unripe ; and the acids, 
 under the same circumstances, are found to vary in a simi- 
 lar manner. We glanced, in a former section, at the exid- 
 ence of inorganic acids and bases in vegetables : we have 
 now to investigate their source. 
 
 The acids found in the different families of plants are 
 very various. It cannot be supposed their presence and pe- 
 culiarities are the result of chance or accident. They must 
 serve some end in vegetable life, independently of their 
 utility to the animals for whose healthful use some, if not 
 all, of them are ultimately destined. Acids constantly ex- 
 ist in vegetables ; and it is incontestable that ihey are ne- 
 cessary to their life. And it is equally certain that some 
 alkaline, earthy, or metallic base, is also indispensable, in 
 order to enter into combination with such acids which are 
 always found in the state of salts, as oxalate of potash in 
 the sour-leaf or sorrel. 
 
 The nature of a soil exercises a decided influence on the 
 quantity of the different metallic oxides contained in the 
 plants which grow on it. It is not known in what form 
 silica, manganese, and oxide of iron, are contained in 
 vegetables ; but we know that potash, soda, and magnesia, 
 can be extracted from all parts of their structure, in 
 the form of salts of organic acids. As these acids and 
 bases are never absent from plants, and as even the 
 form in which they present themselves is subject to no de- 
 viation, it may be affirmed that they are necessary, as exer- 
 cising an important influence over the development of 
 fruits and seeds, and also on many other functions, of the 
 nature of which we are at present ignorant. The perfect 
 development of a plant is dependent, then, on the presence 
 of alkalies, or alkaline earths ; when these substances are 
 totally wanting, its growth will be stopped ; when they 
 are only deficient, it must be correspondingly impeded. 
 Firs and pines find a sufficient quantity of alkalies in bar- 
 ren, sandy soil ; and wheat thrives in another kind of soil : 
 because the bases necessary to bring each to maturity exist 
 
PRODUCTIVE FARMING. 83 
 
 there in sufficient quantity. The proportion of silicate of 
 potash (necessary for the firmness of wheat straw) does not 
 vary perceptibly in the soil of corn-fields, because what is 
 removed by the reaper, is again replaced in putrefying 
 straw. But this is not the case with meadow-land. Hence 
 we never find a luxuriant crop of grass on sandy and lime- 
 stone soils which contain little potash, evidently because 
 one of the constituents indispensable to the growth of the 
 plants is wanting. If a meadow be well manured, we re- 
 move, with the increased crop of grass, a greater quantity 
 of potash than can, by a repetition of the same manure, be 
 restored to it. So, grass-land manured with gypsum soon 
 ceases to feel its agency. But if the meadow be strewed 
 from time to time with wood ashes, or soap-boilers' ley 
 made from wood ashes, then the grass thrives as luxuriantly 
 as before. And why ? The ashes are only a means of re- 
 storing the necessary potash for the grass stalks. So oats, 
 barley, and rye, may be made for once to grow upon a 
 sandy heath, by mixing with the scanty soil the ashes of 
 the heath-plants that grow upon it. Those ashes contain 
 soda and potash, conveyed to the growing furze or gorse 
 by rain-water. The soil of one district consists of sand- 
 stone ; certain trees find in it a quantity of alkaline earths 
 sufficient for their own sustenance. When felled, and 
 burnt, and sprinkled upon the soil, oats will grow and 
 thrive that without such aid would not vegetate. 
 
 The most decisive proof of the absurdity of the indis- 
 criminate use of any strong manure was obtained at Bin- 
 gen, a town on the Rhine, where the produce and develop- 
 ment of vines were highly increased by manuring them 
 with animal matters, such as shavings of horn. After 
 some years, the formation of the wood and leaves decreased 
 perceptibly. Such manure had too much hastened the 
 growth of the vines : in two or three years they had ex- 
 hausted the potash in the formation of their fruit leaves and 
 wood; so that none remained for the future crops, as shav- 
 ings of horn contain no potash. Cow-dung would have 
 been better, and is known to be better. A knowledtre of 
 
84 PRODUCTIVE FARMING. 
 
 chemistry furnishes the reason, which is found in the fac, 
 that it contains a large proportion of potash, though very 
 little nitrogen. Hence, if nitrogen be the element in 
 demand, cow-dung is not the material that will yield it. 
 All the potash contained in the food consumed by a cow, 
 is again immediately discharged in its excrements. 
 
 A landed proprietor, in order to obtain more potash for 
 his soil, planted it with wormwood, the ashes of which are 
 well known to contain a large quantity of that alkali. The 
 consequence was, that he rendered his land quite incapable 
 of bearing grain for many years. He had entirely deprived 
 the soil of its potash. Had he sown wheat upon it instead 
 of wormwood, he w^ould have found the soil contained as 
 much potash as was necessary for the nutrition of that 
 vegetable. The supposition that alkalies, metallic oxides, 
 or inorganic matter in general, are produced by plants, is 
 refuted by such facts as these : they are absorbed by plants, 
 not generated. 
 
 Those grasses, the seeds of which furnish food for man, 
 follow him like the domestic animals. Saline plants re- 
 quire common salt, and seek the sea-shore. The plants 
 which grow on dung-hills need ammonia and the nitrates, 
 and are attracted whither these can be found, just as the 
 dung-fly is to animal excrements. So, likewise, none of our 
 corn plants can bear plump seeds, yielding good and plen- 
 tiful flour, without a large supply of phosphate of magnesia 
 and ammonia, substances which they require for their ma- 
 turity. No soil is richer in them than those where men 
 and animals dwell together. Where the urine and excre- 
 ments of these are found, corn plants appear ; because their 
 seeds cannot attain maturity unless supplied with the con- 
 stituents of these matters. 
 
 During the boiling or evaporation of saltpetre ley, the 
 salt volatilizes with the wafer, causing a loss which other- 
 wise could not be explained. In sea storms, leaves, in the 
 direction of the wind, are covered with crystals of salt, 
 twenty or thirty miles from the sea. The great storm which 
 occurred in England a few winters ago, verifies this state- 
 
PRODUCTIVE FARMING. 85 
 
 ment. But it does not require a storm to cause the vola- 
 tilization of the salt : every breeze must carry it away. 
 The sea-air is always sufficient to make a solution of ni- 
 trate of silver turbid and milky. Now, as millions of tons 
 of sea-water annually evaporate into the atmosphere, a 
 corresponding quantity of the saline matters dissolved in it, 
 common salt, muriate of potash, muriate of magnesia, and 
 other matters, will be conveyed by the wind to the land. 
 This volatilization is a source of considerable loss in salt- 
 works where the quantity of salt in the liquor is not large. 
 
 According to Marcel, sea-water contains in every 1000 
 parts 26 of common salt, 4 of sulphate of soda, or glauber 
 salt, 1^ of muriate of potash, 5J muriate of magnesia, and 
 l^ of sulphate of lime or gypsum. If it be asked, whether 
 there be any peculiarities in the mode of existence of sea- 
 plants and fish, we know that ammonia is found in sea- 
 water ; and that, while air contains only from four to six 
 ten-thousandth parts of its volume of carbonic acid, sea^ 
 water contains 100 times more, or 620 parts in every ten 
 thousand ; so that the same conditions which sustain living 
 beings on the land, are combined in the ocean, in which a 
 separate world of other plants and animals exists. 
 
 By the continual evaporation of the sea, its salts are 
 spread over the whole surface of the earth, subsequently to 
 be carried down by the rain, and furnishing to vegetables, 
 through the micdium of the soil, those saline matters essen- 
 tial to their existence. The salts of potash, magnesia, and 
 soda, are not peculiar to the ocean : they are found natu- 
 rally existing on the land as in the water ; but the above 
 explanation accounts for the origin of alkalies in the ashes 
 of plants in those cases where the soil could not have 
 yielded them. Nor must we overlook the fact, that what- 
 ever be the nature of the soil, or however impoverished by 
 successive crops of alkaline vegetables, upon that surface 
 the distant ocean is for ever, unchangingly, and silently, 
 pouring the saline treasures of the great deep. Were the 
 proportions of land and ocean reversed as to their extent, 
 it is easy to predict the effect upon vegetation ; as it is, the 
 
86 PRODUCTIVE FARMING. 
 
 existing quantity of saline material in the ocean (which 
 coultl not be increased without detriment to its inhabitants) 
 is amply sufficient for the more than single purpose that 
 wise arrangement was destined to answer. The atmos- 
 phere contains only a thousandth part of its w^eight of 
 carbonic acid ; and yet, small as this proportion appears, 
 it is quite sufficient to supply the whole of the present gen- 
 eration of living beings with carbon for a thousand years, 
 even if it were not renewed. Navigators have sailed for 
 hundreds of miles along the unbroken edge of a coral reef: 
 the clustering islands of the Pacific are many of them exclu- 
 sively of coraline origin. Sea-water contains one twelve- 
 thousandth part of its w^eight of lime ; and yet, from this 
 apparently minute quantity, insect agency has raised those 
 very reefs upon which many a huge ship has been dashed 
 into shapeless fragments. 
 
 CHAPTER VII. 
 
 Of the necessary Relation between the Composition of a Soil and 
 the Vegetables it is fitted to raise. Fallowing and Green Crops 
 considered as Vegetable manure. 
 
 The methods employed in the cultivation of land are 
 different in every country; and when we inquire the cause 
 of these differences, we are told that they "depend upon 
 circumstances." Now, as few people have endeavoured to 
 ascertain these circumstances, to reason correctly, and act 
 from rational principle, no answer could show ignorance 
 more plainly. So, when we inquire how manure acts, we 
 are either met with a reply that is figurative and incorrect, 
 or, with the admission that the result is all that is known 
 or cared about. We are told that the excrements of man 
 and animals, or, that certain mineral matters are supposed 
 
PRODUCTIVE FARMING. 87 
 
 to contain an incomprehensible something, which assists 
 in the nourishment of plants, and increases their size. No 
 attempt is made to ascertain the component parts of the 
 different species of manure, much less to ascertam whether 
 it be precisely fitted to supply a known deficiency in the 
 soil. 
 
 Besides heat, light, moisture, and the component ele- 
 ments of the atmosphere, which are necessary for the 
 mere existence of all plants, certain fertilizing substances 
 are seen to exercise a peculiar influence over the develop- 
 ment either of whole plants, or of particular parts of 
 them. Such substances are either already contained in 
 soil, or may be artificially supplied in the form of manure. 
 
 The rules of a rational system of agriculture should 
 enable us, therefore, to give to each plant that which it 
 requires for the attainment of the special object in view 
 — namely, an artificial increase of certain parts which 
 are employed as food for man and animals. 
 
 The means employed for the production of fine pliable 
 straw for hats and bonnets is the very opposite to the mode 
 which must be adopted, in order to produce the largest 
 possible quantity of corn from the same plant. Peculiar 
 methods must be used for the production of nitroo-en 
 in the seeds; others for giving strength to the straw; 
 and others again, when we wish to give such qualities 
 to the straw as will enable it to bear the weight of the 
 ears. 
 
 We must proceed in the artificial rearing and forcing of 
 plants precisely as we do in the fattening of animals. The 
 flesh of wild animals is devoid of fat, or nearly so. The 
 production of flesh and fat may be artificially increased : all 
 domesticated animals are easily fattened. To do this, we 
 add to the quantity of food, and lessen (as in the stall-fed 
 ox) the w^aste occasioned by the increased action of the 
 lungs, (as consequent upon motion,) tooether with the 
 waste w-hich such muscular exertion would produce by in- 
 creased action of the skin. 
 
88 PRODUCTIVE FARMING. 
 
 Arable land is originally formed by the crumbling of 
 rocks, and its properties depend on the nature of its com- 
 ponent parts. 
 
 Sand, clay^ and lime, are the names given to the princi- 
 pal constituents of the different kinds of soil. 
 
 Pure sand, and pure limestone, in which there are no 
 other unorganized substances except the earth of flint, 
 chalk, or silicic acid combined with lime, form absolutely 
 barren soils. But clay always forms a part of fertile soils. 
 "Whence is the origin of clay earths in arable land ? What 
 are their constituents ? and what part do they play in fa- 
 vouring vegetation ? They are produced by the breaking 
 down of aluminums minerals by the action of the weather. 
 These minerals are found, mixed with other substances, in 
 granite, mica-slate, porphyry, clay slate, the volcanic rocks, 
 and others. Mountain limestone is remarkable for the 
 quantity of clayey earths which it contains. In grauwacke 
 we find pure quartz, clay slate, and lime; in the sand- 
 stones, quartz and loam; and in the transition limestone 
 there is an intermixture of clay, felspar, and clay slate. 
 These examples may be sufficient. 
 
 It is known that aluminous minerals (that is to say, 
 minerals containing the metal " aluminium,'^ which, com- 
 bined with oxygen, forms " alumina,'^ or the pure earth 
 of clay) are the most widely diffused on the surface of the 
 earth; and aW fertile soils, or soils capable of culture, in- 
 vaiiably contain alumina. 
 
 There must, therefore, be something in aluminous earth 
 which causes it to exercise an influence on the life of plants, 
 and to assist in their growth. The property on which this 
 depends is, that day invariably contains potash and soda. 
 Besides which alumina attracts and retains water and am- 
 monia from the atmosphere. Alumina is itself very rarely 
 found in the ashes of plants ; but silica (or the earth of 
 flints) is always present, having in most places, enteied 
 the plants by means of alkalies. Among aluminous mine- 
 rals, felspar, which is one of them, contains 17 per cent, of 
 
PRODUCTIVE FARMING. 89 
 
 potash ; mica from 3 to 5 per cent, of soda : clay slate con- 
 tains from 2 to 3 per cent, of potash ; and loam from 1^ to 
 4 per cent, of the same alkali. 
 
 So that, in a layer of soil formed by the breaking down 
 of 40,000 square feet of one of these rocks, to the depth of 
 20 inches, we should find that so much felspar would con- 
 tain more than a million pounds of potash ; if the soil were 
 formed by the disintegration of clay slate, about 200,000; 
 if loam were the material, from 87,000 to 300,000 ; and 
 similarly of other rocks of partially aluminous character. 
 
 Potash is present in all clays, and in marl ; it has been 
 found in all aluminous earths in which it has been sought. 
 Alum (which is a sulphate of alumina, combined with 
 sulphate of potash) may be procured by digesting clay in 
 sulphuric acid, which takes up both the alumina and the 
 potash. 
 
 A thousandth part of loam mixed with the quartz in red 
 sandstone, or with the lime in the different limestone for- 
 mations, affords as much potash to a soil twenty inches in 
 depth as is sufficient to supply a forest of pines growing 
 upon it wuth potash for a hundred years. 
 
 Water, impregnated with the carbonic acid of the at- 
 mosphere, decomposes rocks which contain alkalies, and 
 then dissolves a part of the alkaline carbonates formed in 
 the process. Plants also, by producing carbonic acid 
 during their decay, and by means of the acids emitted by 
 their living roots, contribute no less powerfully to destroy 
 the coherence of solid minerals. Air, water, and changing 
 temperature prepare the different species of rocks for yield- 
 ing to plants the potash or soda they contain. Mrs. Ellis 
 relates, that among the mountains which divide France I'rom 
 Spain, the rocks actually smoke after rain, under the influ- 
 ence of the summer sun, and become so hot that it is un- 
 comfortable to sit down upon them. Changing temperature 
 is a most important agent in nature- It not only assists in 
 the original formation of soils, but exerts a most powerful 
 influence over those already in existence. In wet soils the 
 
 6* 
 
90 PRODUCTIVE FARMING. 
 
 temperature rises slowly, and never attains the same height 
 as in one that is sandy and dry. When the heat of the 
 atmosphere rises no higher in the shade than 60 or 70 de- 
 grees, a dry soil may become so warm as to raise the 
 thermometer to 90 or 100. Hence, though the expression 
 be used figuratively, it is in this instance strictly correct to 
 say that loet soils are cold. 
 
 The exhaustion of alkalies in a soil by successive crops 
 is the true reason why practical farmers sicpjwse themselves 
 compelled to suffer land to lie fallow. It is the greatest possi- 
 ble mistake to think that the temporary diminution of fertility 
 in a field is chiefly owing to the loss of the decaying vegetable 
 matter it previously contained : it is principally the conse- 
 quence of the exhaustion of potash and soda, which are 
 restored by the slow process of the more complete disin- 
 tegration of the materials of the soil. It is evident that 
 the careful tilling of fallow land must accelerate and in- 
 crease this further breaking up of its mineral ingredients. 
 Nor is this repose of the soil always necessary. A field, 
 which has become unfitted for a certain kind of produce, 
 may not, on that account, be unsuitable for another; and 
 upon this observation a system of agriculture has been 
 gradually formed, the principal object of which is to obtain 
 the greatest possible produce in a succession of years, with 
 the least outlay for manure. Because plants require for 
 their growth different constituents of soil, changing the 
 crop from year to year will maintain the fertility of that 
 soil (provided it be done with judgment) quite as well as 
 leaving it at rest or fallow. In this we but imitate nature. 
 The oak, after thriving for long generations on a particular 
 spot, gradually sickens; its entire race dies out; other 
 trees and shrubs succeed it, till, at length, the surface be- 
 comes so charged with an excess of dead vegetable mat- 
 ter, that the forest becomes a peat moss, or a surface upon 
 which no large tree will grow. Generally long before this 
 can occur, the operation of natural causes has gradually 
 removed from the soil substances essential to the growth of 
 oak, leaving others favourable and necessary to the growth 
 
PRODUCTIVE FARMING. 91 
 
 of beech or pine. So, in practical farming, one crop in 
 artificial rotation with others, extracts from the soil a cer- 
 tain quantity of necessary inorganic matters; a second 
 carries off, in preference, those which the former had left, 
 and neither could nor would take up. 
 
 Experience proves that wheat should not be attempted 
 to be raised after wheat on the same soil ; for, like tobacco, 
 it exhausts the soil. But, if " humus," decaying vegetable 
 matter, gives it the power of producing corn, how happens 
 it that, in soils formed in large proportion of mouldered 
 wood, the corn-stalk attains no strength, and droops per- 
 manently ? The cause is this; the strength of the stalk is 
 due to siliciate of potash^ and the corn requires 'phosphate 
 of magnesia ; neither of which substances a soil of decay- 
 inor vegetable matter can afford, since it does not contain 
 them: the plant may, indeed, under such circumstances, 
 become an herb, but it will bear no seeds. We say phos- 
 phate of magnesia is necessary ; — the small quantities of 
 the phosphates found in peas and beans is the cause of their 
 comparatively small value as articles of nourishment, since 
 they surpass all other vegetable food in the quantity of 
 nitrogen they contain. But as the component parts of 
 bone, namely phosphate of lime and magnesia, are absent in 
 beans and peas, they satisfy appetite without increasing 
 the strength. 
 
 Again, how does it happen that wheat does not flourish 
 on a sandy soil, and that a limestone soil is also unsuitable, 
 unless mixed with a considerable quantity of clay 1 Evi- 
 dently because these soils do not contain potash and soda, 
 (always found in clay ;) the growth of wheat being ar- 
 rested by this circumstance, even should all other requisite 
 substances be presented in abundance. It is because they 
 are mutually prejudicial by appropriating the alkalies of 
 the soil, that wormwood will not thrive where wheat has 
 grown, nor wheat where wormwood has been. 
 
 One hundred parts of wheat straw yield 15^ of^ashes; 
 the same quantity of barley straw, S} ; of oat straw, only 
 4 ^ the ashes of the three are, chemically, of the same 
 
92 PRODUCTIVE FARMING. 
 
 composition. Upon the same field which will yield only 
 one harvest of wheat, two successive crops of barley may 
 be raised, and three of oats. We have, in these facts, a 
 clear proof of what is abstracted from the soil, and, con- 
 sequently, what plants require for their growth, — a key to 
 the rational mode of supplying the deficiency. 
 
 Potash is not the only substance requisite for the exist- 
 ence of most plants; indeed it may be replaced, in some 
 cases, by soda, magnesia, or lime ; but other substances 
 are required also. 
 
 Plants obtain ;?/i05p^oWc acid (found in combination with 
 lime or magnesia) from the soil, and they, in their turn, 
 yield it to animals, to assist in the formation of their bones. 
 Creatures that feed upon flesh, bread, fruit, and husks of 
 grain, take in much more phosphorus than is required for 
 rhe building up of the animal fabric ; and this excess is 
 again usefully thrown out by them, chiefly in their liquid 
 excrements. Some plants, however, extract other matters 
 from the soil besides silica, potash, and phosphoric acid, 
 which are essential constituents of the plants ordinarily 
 cultivated. 
 
 English farming presents us with varied instances of 
 pl'.ints sown, and growing together in the same field. Two 
 such vegetables will mutually injure each other, if they 
 withdraw the same food from the soil. Plants w'ill thrive 
 beside each other, either when the substances necessary for 
 their growth, extracted from the soil, are of different kinds, 
 or when they themselves are not both in the same stage of 
 growth at the same time. On a soil containing potash, 
 wheat and tobacco may be reared in succession, because 
 the latter plant does not require the phosphates which the 
 wheat has appropriated to itself. Now, tobacco requires 
 only alkalies, and food containing nitrogen. When we 
 grow different plants in the same soil, for several years in 
 succession, the first of which leaves behind that which the 
 second, and the second that which the third may require, 
 the soil will be a fruitful one for all the three kinds of 
 produce. If the first plant, for example, be wheat, which 
 
PRODUCTIVE FARMING. 93 
 
 consumes the greatest part of the silicate of potash in the 
 soil, the plants which succeed it should be such as require 
 little potash, as turnips or potatoes. The wheat lands rnay 
 be sown again with wheat, advantageously, after the fourth 
 year. The reason of this is, that during the interval of 
 three years, the soil will, hy the action of the atmosphere, 
 be rendered capable of again yielding silicate of potash in 
 sufficient quantity for wheat. Whether this process can be 
 artificially anticipated, by supplying the exhausted ingre- 
 dient to the soil, is a further, and most interesting inquiry. 
 In a four-years' course of cropping, the crops gathered 
 amounted, per acre, to — 
 
 1st year, Turnips, 25 tons of bulbs, and 7 tons of tops. 
 2d year, Barley, 38 bushels, and a ton of straw. 
 3d year, Clover and Rye Grass, 1 ton of each in hay. 
 4th year. Wheat, 25 bushels, and 2 tons of straw. 
 
 Supposing none of the crops to be eaten upon the land, 
 the quantity of inorganic matter contained in the above 
 would be as follows : — 
 
 lbs. 
 
 lbs. 
 
 
 Potash, 281 
 
 Silica, 318 
 
 
 Soda, 130 
 
 Sulphuric acid. 111 j 
 
 ) in combination 
 
 Lime, 242 
 
 Phosphoric acid, 61 ; 
 
 > with the earths 
 
 Magnesia, 42 
 
 Chlorine, 39 ] 
 
 ) and alkalies ', 
 
 Alumina, 11 
 
 making a gross weight of 1240 pounds, or about eleven 
 hundred weight. 
 
 A still clearer idea of the importance and quantities of 
 these inorganic matters, may be obtained by a consideration 
 of the fact, that if we were to carry off the entire of the 
 above produce, and return none of it again in the shape of 
 manure, (supposing also that we could stop the beneficial 
 agency of the atmosphere during that period,) we must, or 
 ought, instead of that produce, — if the land is to be restored 
 to its original condition, — add to each acre, every four 
 years, 300 pounds of pearl ashes, or potash ; 440 of car- 
 
94 PRODUCTIVE FARMING. 
 
 bonate of soda; 65 of common salt; 240 of quick lime ; 
 250 of sulphate of magnesia, that is, Epsom salts ; 84 of 
 alum ; and 260 of bone dust : making 1729 pounds of solid 
 saline matter, at an expense of nearly «£9. The fertility of 
 a soil cannot remain long unimpaired, unless we replace 
 in it all those substances of which it has been deprived. 
 We could keep our fields in a constant state of fertility, by 
 replacing, every year, as much as we remove from them in 
 the form of produce ; and, be it remembered, that our cul- 
 tivated corn plants, and bulbous roots, are not like forest 
 plants and trees : the quantity of nutriment they require, 
 and take up, to bring them to perfection and perpetuate the 
 race, is far more than the unaided elements around them 
 could supply. Wheat, for instance, as a natural production 
 of the soil, appears to have been a very small grass : and 
 the case is still more remaikable with the apple and the 
 plum. The common crab seems to have been the parent 
 of all our apples. Potatoes and turnips, in their wild or 
 natural state, are unfit for food ; and two fruits can scarcely 
 be conceived more different in colour, size, and appearance, 
 than the wild plum and the rich magnum bonum. We 
 have to contend, then, with two important differences : 
 First, That wheat or turnips are not natural productions ; 
 and, secondly, That because they are not, they drain or 
 exhaust unassisted soil faster than the wild plants of the 
 forest ; nor will they thrive long, if denied that assistance 
 from artificial nutriment, which nature cannot supply in 
 sufficient quantity. 
 
 It is evident, then, that an increase of fertility, and con- 
 sequent increase of crop, can only be expected when we 
 add more to the soil of the proper, imterh], [and no other,) 
 than we take away. Any soil will partially regain itself 
 by lying fallow : this is owing to atmospheric action, and 
 the conversion of the roots and stalks into humus. But 
 though the quantity of decaying vegetable humus in a soil 
 may be increased to a certain degree by cultivation and 
 alternate cropping, still there cannot be the smallest doubt. 
 
PRODUCTIVE FARMING. 95 
 
 that a soil must (without help) ultimately lose those of its 
 constituents, which are removed in the seeds, roots, and 
 leaves of the plants raised upon it. 
 
 To prevent this loss, and, as a further object, to enable 
 us to raise increased quantities of productions, demanding 
 more sustenance than the land will naturally yield, is the 
 object of the application of the various substances used as 
 MANURES. They will prove useless, injurious, or valuable, 
 precisely as they are accurately or inaccurately adapted to 
 meet the deficiency. 
 
 Land, when not employed in raising food for animals 
 or man, should, at least, be applied to the purpose of raising 
 manure for itself; and this, to a certain extent, may be 
 eifecled by means o^ green crops, which, by their decom- 
 position, not only add to the amount of vegetable mould 
 contained in the soil, but supply the alkalies that would be 
 found in their ashes. That the soil should become richer 
 by this burial of a crop, than it was before the seed of that 
 crop was sow^n, will be understood by recollecting that 
 three-fourths of the whole organic matter we bury has been 
 derived from the air: that by this process of ploughing in, 
 the vegetable matter is more equally diffused through the 
 w^iole soil, and therefore more easily and rapidly decom- 
 posed ; and that by its gradual decomposition, ammonia 
 and nitric acid are certainly generated, though not so 
 largely as when animal matters are employed. He who 
 neglects the green sods, and crops of weeds that flourish by 
 his hedgerows and ditches, overlooks an important natural 
 means of wealth. Left to themselves, they ripen their 
 seeds, exhausting the soil, and sowing them annually in his 
 fields: collected in compost heaps, they add materially to 
 his yearly crops of corn. We have said that absolute re- 
 pose of the soil is not frequently needed ; and, with some 
 practical illustrations of the system of alternate cropping, 
 we will close this section. 
 
 In Flanders, two crops of clover are cut, and the third 
 is ploughed in. In Sussex, turnip seed has been sown at 
 
96 PRODUCTIVE FARMING. 
 
 the end of harvest, and, after two months, again ploughed 
 in with great benefit to the land. So turnip leaves and 
 potato tops decay rapidly, and are more enriching when 
 buried in the green state. In the Earl of Leicester's 
 course of cropping, the land is never idle. The turnip is 
 the first in the oider of succession. This crop is ma- 
 nured with recent dung, which immediately affords suffi- 
 cient matter for its nourishment ; the heat produced in its 
 decomposition assisting in the extrication of ammonia, the 
 liberation of nitrogen, and the consequent germination of 
 the seed, and growth of the plant. Next after turnips, 
 barley, with grass seeds, is sown ; and the land having 
 been little exhausted by the previous crop of turnips, affords 
 the soluble parts of the decomposing tops and manure to 
 the barley. The barley is gathered ; the grasses, rye-grass 
 and clover, remain, which derive a small part only of their 
 organized matter from the soil, and probably consume the 
 gypsum- which would be useless to previous and succeeding 
 crops. These grasses, by their large system of leaves, ab- 
 sorb mainly their nutriment from the atmosphere ; and, 
 when PLOUGHED IN at the end of two years, their decompos- 
 ed roots and leaves are useful to the wheat crop, which is 
 next, and last in succession. At this period of the course, 
 the woody fibre of the farm-yard manure, containing phos- 
 phate of lime, is sufficiently decomposed ; and as soon as 
 the most exhausting crop is taken off the land, recent ani- 
 mal manure is again applied. Pease and beans, in all in- 
 stances, seem well adapted to prepare the ground for 
 wheat ; and in some parts of the country they are raised, 
 alternately with wheat, for years together. Mr. Gregg, — 
 whose ingenious system of cultivation has been published 
 by the Board of Agriculture, and who adopts, upon strong 
 clays, a plan similar to that of the Earl of Leicester, (bet- 
 ter known as Mr. Coke of Holkham,) — suffers the ground, 
 after barley, to remain at rest for two years in grass ; sows 
 pease and beans[onJthe leys; ploughs in the pea or bean stub- 
 ble for wheat ; and, in some instances, follows his wheat 
 
PRODUCTIVE FARMING. 97 
 
 crops by a course of winter tares and winter barley, 
 which is eaten off in the spring before the land is sown lor 
 turnips. 
 
 It is a great advantRge, in the convertible system of 
 cultivation, that the whole of the manure is employed as 
 well as the entire resources of the land, in their proper 
 order ; those materials which are not fitted for one crop, 
 remaining as nutriment, or essential requisites for the next, 
 or for another. 
 
 CHAPTER VIII. 
 
 Of the Nature and correct Use of the Excrements of Animals con- 
 sidered as Manure; the Mode of its Action and Preservation. — 
 Bone Dust, and dead Animal Matter. 
 
 Calico printers for a long time have used the solid 
 excrements of the cow in order to brighten and fasten col- 
 ours on cotton cloth. This material appeared quite neces- 
 sary, and its action was ascribed to some latent principle 
 or material derivable from the living animal. But since 
 the action of cow-dung was known to depend on ihe phos^ 
 phates contained in it, it has been completely replaced by 
 a more cleanly mixture of certain salts, of which the most 
 prominent is phosphate of soda. 
 
 So, similarly, in medicine, for many centuries the mode 
 of action, or the active principle of all remedies, was veiled 
 in obscurity. But now^ these principles have been present- 
 ed to the world in an extremely active and concentiated 
 form. The extraordinary efficacy of Peruvian bark in the 
 cure of fever, is found to depend on the admixture of a 
 minute quantity of a crystalline substance termed quinine, 
 with the useless W'oody fibre 3 and the causes of the various 
 
98 PRODUCTIVE FARMING. 
 
 effects of opium, in as many equally minute yet poweiful 
 ini^rerlients in that clru(>;. The inhabitants of Savoy are 
 much infested with the disease known among us as "Der- 
 byshire neck." They have sprin^^s which are famous for 
 its cure ; we derive benefit from the use of burnt sponge. 
 Now, burnt sponge contains iodine ; and upon examina- 
 tion these springs contain iodine in small quantities. The 
 action of the sponge, or of the w^ater, must depend upon 
 some definite cause common to both ; by ascertaining 
 which we place the action and result completely at our 
 command. 
 
 Apply this reasoning to agricultural operations. One 
 practical farmer applies, indiscriminately, any fertilizing- 
 material to his land in any state ; another, more partial to 
 what is technically termed " short muck," allows violent 
 fermentation to reduce his mixture of straw and dung to 
 one half its weight, — during which operation much gas- 
 eous ammonia is disengaged and lost, which, if retained, 
 or supplied to the soil, would have proved extremely ser- 
 viceable. Both methods cannot be right in all cases. 
 
 Besides the dissipation of gaseous matter when fer- 
 mentation is pushed to the extreme, there is another disad- 
 vantage in the loss of heat^ which, if excited in the soil 
 instead of the dunghill, is useful in promoting the springing 
 of the seed, and in assisting the plant in the first stage of 
 its growth, when it is most feeble and most liable to dis- 
 ease : and the decomposition of manure in the soil must be 
 particularly favourable to the wheat crop, in preserving a 
 genial temperature beneath the surface late in autumn and 
 during winter. These views are in accordance with a 
 well-known principle in chemistry, — that, in all cases of 
 decomposition, substances combine much more readily at 
 the moment of their disengagement than after they have 
 been some time perfectly formed and set at liberty. And 
 in fermentation beneath the soil, the fluid matter produced 
 is applied instantly, even whilst it is warm, to the young 
 organs of the rising plant; and, consequently, is more 
 
PRODUCTIVE FARMING. 99 
 
 likely to be efficient, than in manure that has gone through 
 the process, and of which all the principles have entered 
 into new combinations. 
 
 It is certainly a matter of inditference whether we em- 
 ploy excrements, ashes, or bones, in carrying out the 
 principle of restoring to the soil those substances which 
 have been taken from it by the previous crop. But, unless 
 we know accurately what are those matters that have been 
 actually removed, how is it possible to supply, otherwise 
 than at random guess, the deficiency ? Fermented dung 
 may be really useful, if wo nitrogen be demanded. A time 
 will come when fields will be manured with saline solu- 
 tions, with the ashes of burnt straw, or with salts of phos- 
 phoric acid prepared in chemical manufactories, with as 
 much certainty as now, in medicine, iodine cures the Der- 
 byshire neck, or as quinine is substituted for the bulky 
 powdered bark in fever. The same mixed mass of mate- 
 rials may be useful in one state, less so in another and un- 
 der other circumstances. A knowledge of the actual wants 
 of the land, and of the exact composition of the proposed 
 manure, is obviously necessary to enable the farmer to 
 adapt the one to the other as a requisite and fitting remedy. 
 If our object be the development of the seeds of plants, we 
 know they contain nitrogen. Our manure then must be rich 
 in this material. If by fermentation ammonia be formed in 
 the manure, if it become dry, rotten, and nearly devoid of 
 smell, having lost its previous heat; although it may cut 
 better with the spade, we may be sure it has lost its nitio- 
 gen, and, consequently, as far as our object is concerned, 
 (the nutriment of the seed,) nearly lost its utility. The 
 leaves, which by their action on the air nourish the stem 
 and woody fibre; the roots, from which the leaves are 
 formed ; in short, every part of the structure of a plant 
 contains nitrogen in small and varying proportions. But 
 the seeds are always rich in nitrogen. 
 
 The most important object, then, of farming operations, 
 at least as far as corn is concerned, is the supply of nitrogen 
 to com plants in a state capable of being taken up by them, 
 
100 PRODUCTIVE FARMING. 
 
 — the production, therefore, of manures containing the 
 most of this element. Gypsum and nitrate of soda are as 
 properly termed manures as I'aim-yard dung, bone-dust, or 
 night soil ; but our present inquiry is, what class of sub- 
 stances contain and yield to corn-plants most nitrogen? 
 Nature, by the ordinary action of the atmosphere, furnishes 
 as ujuch nitrogen to a plant as is necessary to its bare ex- 
 istence. But plants do not exist for themselves alone : — 
 the greater number of animals depend upon the vegetable 
 Avorld for food ; and, by a wise adjustment of nature, plants 
 have the remarkable power of converting, to a certain 
 degree, all the nitrogen offered to them into nutriment for 
 animals. We may furnish a plant with carbonic acid, and 
 all the materials which it may require for its mere life; we 
 may supply it with vegetable matter in a state of decay in 
 the most abundant quantity ; but it will not attain complete 
 development unless nitrogen be afforded to it by the supply 
 of suitable manure: an herb will, indeed, be formed, but 
 its seeds or grain will be imperfect and feeble. 
 
 But when, with proper manure, we supply nitrogen in 
 addition to what the plant would derive from natural sour- 
 ces, we enable it to attract from the air the carbon which 
 is necessary for its nutrition — that is, when that in the soil 
 is not sufficient, we afford it a means of fixing the atmos- 
 pheric carbon. 
 
 There are two principal descriptions of manure, the 
 beneficial agency of which is derivable almost exclusively 
 from the large quantity of nitrogen they yield. 
 
 These are tlie solid as well as fluid excrements of man 
 and animals, their dung and urine. 
 
 Urine is employed as manure either singly, in its liquid 
 state, or with the fseces which are impregnated wiih it. It 
 is the urine contained in night-soil which gives it the pro- 
 perty of giving off ammonia, a propeity which the dis- 
 charges from the bowels possess only in a very slight 
 degree. Liquid manures act chiefly through the saline 
 substances they hold in solution ; whild the solid manures, 
 even of animal origin, contain insoluble matters which 
 
PRODUCTIVE FARMING. 101 
 
 decay slowly in the soil, and there become useful only after 
 a time. When we examine what substances we add to a 
 soil by supplying it w^ith urine, we find that this liquid con- 
 tains in solution ammoniacal salts, uric acid, (a substance 
 itself containing much nitrogen,) and salts of phosphoric 
 acid. 
 
 Human urine consists in 1000 parts of 
 
 Water, 932 
 
 Urea, and other organic matters containing ni- > .^ 
 
 trogen, 5 
 
 Phosphates of ammonia, soda, lime, and mag- ) ^ 
 
 nesia, ) 
 
 Sulphates of soda and ammonia, ... 7 
 
 Sal-ammoniac and common salt, ... 6 
 
 1000 
 
 In dung reservoirs, well constructed and protected from 
 evaporation, the carbonate of ammonia, which forms in 
 consequence of putrefaction, is retained in solution ; and 
 when the putrefied urine is spread over the land, a part of 
 this ammonia will escape with the water which evaporates. 
 On account of the formation of carbonate of ammonia in 
 putrid urine, it becomes alkaline, though naturally acid in 
 its recent state; and when this carbonate of ammonia is 
 lost by being volatilized in the air, (which happens in most 
 cases,) the loss suffered is nearly equal to one half of the 
 urine employed. So that, if we fix the ammonia, (by com- 
 bining it with some acid which forms with it a compound 
 not volatile,) we increase its action twofold. Now the 
 carbonate of ammonia formed by the putrefaction of urine 
 can he fixed, or deprived of its volatility, in many w^ays. 
 
 If, for instance, a field be strewed with gypsum, or 
 plaster of Paris, (in chemical language, sulphate of lime,) 
 and then sprinkled with urine, or the drainings of the cow- 
 shed, a double exchange or decomposition takes place. 
 Sulphate of lime and carbonate of ammonia become con- 
 verted into carbonate of lime (that is, chalk) and sulphate 
 of ammonia ; and this because sulphuric acid has a greater 
 
102 PRODUCTIVE FARMING. 
 
 affinity for ammonia than it has for lime. This sulphate of 
 ammonia will remain in the soil — it will not evaporate. 
 
 If a basin containing s})irit of salt, or muriatic acid, be 
 left a few weeks in a close stable or privy, so that its sur- 
 face is in free communication with the ammoniacal vapours 
 that rise from below, crystals of muriate of ammonia, or 
 common sal-ammoniac, will soon be visible, as an incrusta- 
 tion about its edges. The ammonia that escapes in this 
 way is not only entirely lost as far as vegetation is con- 
 cerned ; it works also a slow but not less certain destruc- 
 tion of the mortar and plaster of the building. For when 
 in contact with the lime of the mortar, ammonia is con- 
 verted into nitric acid, which gradually dissolves the lime. 
 There are few schoolboys who have not picked out crys- 
 tals of nitrate of potass, or saltpetre, from an old brick- 
 wall ; and in this instance the atmosphere has yielded the 
 ammonia. 
 
 The offensive carbonate of ammonia in close stables is 
 very injurious to the eyes and lungs of horses, as the army 
 veterinary surgeons are well able to testify. They adopt 
 measures to carry it off by ventilation and cleanliness. If 
 the floors or stables of cow-sheds were strewed with com- 
 mon gypsum, they would lose all their offensive and inju- 
 rious smell, and none of the ammonia which forms could 
 be lost, but would be retained in a condition serviceable as 
 manure. This composition, swept from the stable floor, 
 nearly constitutes what is sold under the denomination of 
 urate. Manufacturers of this material state, that three or 
 four hundred weight of urate form sufficient manure for an 
 acre : a far more promising adventure for a practical farmer 
 will be to go to some expense in saving his own liquid 
 manure, and, after mixing it with burnt gypsum, to lay it 
 abundantly upon his corn-lands. For, in this way, he may 
 use as much gypsum as will absorb the whole of the urine. 
 Now, in the manufacture o{ urate, the proportion of 10 
 pounds is employed to every 7 gallons,— allowing the mix- 
 ture, occasionally stirred, to stand some time, pounng off" 
 the liquid^ and with it nearly all its saline contents, excej t 
 
PRODUCTIVE FARMING. 103 
 
 the ammonia. Urate, therefore, can never present all the 
 virtues of the urine — 100 pounds of urate containin^^ no 
 greater weight of saline and organic matter than 10 gallons 
 of urine. 
 
 From the foregoing analysis it wouh! appear, that 1000 
 pounds of human urine contain no less than 68 pounds of 
 dry fertilizing matter of the richest quality, worth, at the 
 present rate of selling artificial manures in this country, 
 at least twenty shillings per hundred weight. Suppose 
 we say that the liquid and solid excrements of one hu- 
 man being amount on an average to a pound and a-half 
 daily, then in one year they will amount to 547 pounds ; 
 ^vhich at the rate of three per cent, of contained nitro- 
 gen, would yield sixteen pounds of that material for the 
 land, a quantity sufficient to supply enough for eight 
 hundred pounds of wheat, rye, or oats, or for nine hun- 
 dred pounds of barley. As each person in reality voids at 
 least one thousand pounds or pints of urine in a year, the 
 national waste incurred in this form amounts, at the 
 above valuation, to twelve shillings a-head upon every 
 individual of the whole population of England and Wales. 
 And if five tons of farm-yard manure per acre, added 
 yearly, will keep a farm in good order, four hundred 
 weight of the solid matter of urine would probably have 
 an equal effect — in other words, the excrements of a a sin- 
 gle individual, are more than sufficient to yield the requi- 
 site nitrogen to an acre of land, in order to enable it 
 (with the assistance of the nitrogen absorbed naturally from 
 the atmosphere) to produce the richest possible yearly 
 crop. Every town and farm might thus supply itself 
 with the manure, which, besides containing the most nitro- 
 gen, contains also the most phosphates ; and if an alterna- 
 tion of the crops were adopted, they would be most abun- 
 dant. By using at the same time bones and wood ashes, 
 the excrements of animals might be completely dispensed 
 with. So that artificial, mineral, or chemical manures are 
 no imperfect substitutes, if applied judiciously. 
 
 The urine alone discharged into rivers or sew^ers by a 
 
104 PRODUCTIVE FARMINa 
 
 town population of 10,000 inhabitants wcmld supply ma- 
 nure to a farm of 1500 acres, yielding a return of 4,500 
 quarters of corn, or an equivolent produce of other crops. 
 The powerful agency of urine as a manure is well known 
 on the Continent, and the Chinese justly consider it as 
 invaluable ; and they are the oldest as well as the best 
 agriculturists in the v^rorld. Indeed so much value is at- 
 tached to human excrements by the Chinese, that the 
 laws of the country forbid that any of them should be 
 thrown away ; and reservoirs are placed in every house, 
 where they are collected with the utmost care. jYo other 
 kind of manure is used for their corn-fields. 
 
 Human urine contains a greater variety of constituents 
 than any other species examined. Urea, uric acid, and 
 another acid similar to it in nature called rosacic acid, acetic 
 acid, albumen, gelatine, a resinous matter, and its various 
 salts, are all valuable to the land, inasmuch as from the 
 land they or their elements have been originally derived. 
 The urine of animals that feed exclusively on flesh contains 
 more animal matter, and consequently more nitrogen, than 
 that of vegetable feeders, whence it is more apt to run into 
 the putrefactive process and disengage ammonia. In pro- 
 portion as there are more gelatine and albumen in urine, so 
 in proportion does it putrefy more rapidly. Thus, then, all 
 urine contains the essential elements of vegetables in a 
 state of solution ; and that will be the best for manure 
 which contains most albumen, gelatine, and urea. Putrid 
 urine abounds in ammoniacal salts, and is only less active 
 as a manure than fresh urine, because of the portion of 
 ammonia which is continually exhaling into the atmos- 
 phere. 
 
 As to the urine of cattle, it contains less water than that 
 of man, varying with the kind of food on which the animal 
 is fed. A cow will secrete and discharge from two thou- 
 sand to three thousand gallons of urine a year ; and this 
 quantity will contain at least from 1200 to 1500 pounds of 
 dry solid saline matters, worth from ten to twelve pounds 
 sterling monies of the realm. Even in the liquid state, the 
 
PRODUCTIVE FARMING. 105 
 
 urine of one cow, collected and preserved as it is in Flan- 
 ders, is valued in that country at about £2 a-year. Any prac- 
 tical English farmer may easily make the calculation for 
 himself, how much real w^ealth is lost in his own farm- 
 yard, how much of the natural means of reproductive indus- 
 try passes into his drains or evaporates in the air. 
 
 The urine of the cow is particularly rich in salts of pot- 
 ash, but contains very little soda. The urine of swnne con- 
 tains a large quantity of the phosphates of ammonia and 
 magnesia. That of the horse contains less nitrogen and 
 phosphates than that of man. 
 
 The fertilizing powers o^ animal manures, w^iether fluid 
 or solid, is dependent, like that of the soil itself, upon the 
 happy admixture of a great number, if not of all, those 
 substances which are required by plants in the universal 
 cultivation they receive from the industry and skill of man, 
 more especially upon the large proportion of nitrogen they 
 contain. The amount of this latter material affords the 
 readiest test by which their agricultural value, compared 
 with other matters and with that of each other, can be tol- 
 erably well estimated. 
 
 Ordinary farm-yard manure, in its recent state, contains 
 a given proportion of nitrogen ; but fifteen pounds of blood 
 would yield as much nitrogen as one hundred pounds of 
 farm-yard compost. If dried blood were taken, four pounds 
 would be sufficient ; three pounds of feathers, three of horn 
 shavings, five of pigeon's dung, or even two and a half of 
 woollen rags, would counterpoise one hundred of the first 
 named material. Sixteen w^ould be the equivalent number 
 for the urine of the horse, ninety-one that of the cow, sev- 
 enty-three for horse-dung, one hundred and twenty -five for 
 cow-dung ; while the mixed excrements of either animals 
 would correspond wath the fact that the discharges of the 
 cow offer no resemblance to those of the horse. 
 
 Besides their general relative value, namely, as to the 
 proportions of nitrogen they contain, the above matters 
 have a further special value, dependent upon the diversity 
 of saline and other organic matters which they severally 
 
 6 
 
106 PRODUCTIVE FARMLNG. 
 
 contain. Thus, three of dried flesh are equal to five of 
 pigeons' dung, as far as nitrogen is concerned ; but then 
 pigeons' dung contains a quantity of bone, earth, and saline 
 matter, scarcely present in the former. Hence, the dung 
 of fowls will benefit vegetation in some instances where 
 even horse-flesh, ortlinarily regarded as a strong manure, 
 would fail. And why ? Evidently because, if saline mat- 
 ters are deficient in the soil, an excessive supply of nitro- 
 gen will not serve as their substitute. So the liquid ex- 
 cretions contain much important sali7}e matter not present 
 in solid dung, nor in such substances as horn, hair, or wool; 
 and therefore each must be capable of exercising its own 
 peculiar influence, and be comparatively useless if deficient 
 of those matters which are also found wanting, delicient, 
 yet necessary in the soil. This affords the reason why no 
 one manure can long answer on the same land ; it can only 
 supply the materials it contains. When all the silicate of 
 potash in corn-fields is exhausted, urine will not, cannot, 
 supply the deficiency, because it contains no silicate of 
 potash. So long as the land remained rich in this material, 
 urine or blood would supply the requisite nitrogen. Hence, 
 in all ages and countries, the habit of employing inixed 
 manures and artificial composts has been universally dif- 
 fused. What is wanting is a rpore accurate knowledge of 
 the precise deficiency at any given moment, and a conse- 
 quent saving of capital from unnecessary waste, together 
 with an immense increase in fertility, as the reward of so 
 accurate an adaptation of means and ends. The know- 
 ledge of a disease is essential to the correct application of 
 a remedy. 
 
 A high degree of culture requires an increased supply 
 of manure. With its abundance, the produce in corn and 
 cattle will augment, but must diminish with its deficiency. 
 
 From the foregoing remarks, it must be evident, that the 
 greatest value should be attached to the liquid excrements 
 of man and animals when a manure is desired which shall 
 supply nitrogen to the soil. And as nitrogen is seldom 
 wanted alone, — and as, generally, in practice, both liquid 
 
PRODUCTIVE FARMING. 107 
 
 and solid excrements are found associated, containing, be- 
 sides nitrogen, many other essential and invaluable ingredi- 
 ents, — too much care cannot be taken, not only in preserving 
 them, but, which is equally important, in securing to the 
 land the full value of their operation, by applying them, 
 in the best possible condition, for the development of their 
 powers. 
 
 We have already alluded to the loss sustained by the 
 fermentation of dung-heaps. As we observed, in an earlier 
 section, when it is considered that, with every jiound of 
 ammonia which evaporates, a loss of sixty 'pounds of corn 
 is sustained, and that, with every pound of urine, a pound 
 of wheat might be produced, the indifference with which 
 liquid refuse is allowed to run to waste is quite incompre- 
 hensible. That it should be allowed to expend its ammo- 
 nia by fermentation in the dung-heap, and evaporation into 
 the atmosphere, is ascribable solely to ignorance of the 
 elementary outlines of that science which hitherto the prac- 
 tical farmer has thought it no disgrace, but rather an honour 
 to publish, glorying in his utter disregard of all bookish 
 knowledge, and substituting his own notions of wasteful 
 and vague experience, for the calm deductions of sound 
 and rational investigation. In most places, only the solid 
 excrements impregnated with the liquid are used ; and the 
 dunghills containing them are protected neither from eva- 
 poration, nor from rain. The solid excrements contain the 
 insoluble, the liquid excrements all the soluble phosphates ; 
 and the latter contain, likewise, all the potash which ex- 
 isted as organic salts in the plants consumed by the ani- 
 mals which feed upon them. 
 
 It is by no means difficult to prevent the destructive 
 fermentation and heating of farm-yard compost. The sur- 
 face should be defended from the oxygen of the atmos- 
 phere. A compact marl, or a tenacious clay, offers the 
 best protection against the air ; and before the dung is cov- 
 ered over, or, as it were, sealed up, it should be dried as 
 much as possible. If the dung be found at any time to 
 heat strongly, it should be turned over, and cooled by ex- 
 
108 PRODUCTIVE FARMING. 
 
 posure to air. Watering dung-hills is sometimes recom- 
 mended for checking the process of putrefaction, and 
 the consequent escape of ammonia ; but this practice is 
 not consistent with correct chemistry. It may cool the 
 dung for a short time ; but moisture is a principal agent in 
 all processes of decomposition. Water, or moisture, is as 
 necessary to the change as air ; and to supply it to reeking 
 dung, is to supply an agent which will hasten its decay. 
 
 If a thermometer, plunged into the dung, does not rise 
 much above blood-heat, there is little danger of the escape 
 of ammonia. When a piece of paper, moistened with 
 spirit of salt, or muriatic acid, held over the steams arising 
 from a dung-hill, gives dense fumes, it is a certain test that 
 decomposition is going too far ; for this indicates that am- 
 monia is not only formed, but is escaping to unite with the 
 acid in the shape of sal-ammoniac. 
 
 When dung is to be preserved for any time, the situa- 
 tion in which it is kept is of importance. It should, if 
 possible, be defended from the sun. To preserve it under 
 sheds w^ould be of great use, or to make the site of a dung- 
 hill on the north side of a wall. The floor on which the 
 dung is heaped, should, if possible, be paved with flat 
 stones ; and there should be a httle inclination from each side 
 towards the centre, in which there should be drains, con- 
 nected with a small well, furnished with a pump, by w^hich 
 any fluid matter may be collected for the use of the land. 
 It too often happens, that a heavy, thick, extractive fluid is 
 suffered to drain away from the dung-hill, so as to be en- 
 tirely lost to the farm. 
 
 JVight-soil, it is well known, is a very powerful manure, 
 and very liable to decompose. Human excrements differ 
 in their composition, but always abound in nitrogen, hydro- 
 gen, carbon, and oxygen. From the analysis of Berzelius, 
 it appears that a part of it is always soluble in water; and 
 in whatever state it is used, whether recent or decomposed, 
 it supplies abundant food to plants. But this affords no 
 excuse for its misapplication in any other condition than 
 that which is most profitable. It varies, no doubt, in rich- 
 
PRODUCTIVE FARMING. 109 
 
 ness with the food of the inhabitants of each district, — 
 chiefly with the quantity of animal food they consume, — • 
 but, when dry, no other solid manure, w^eight for weight, 
 can probably be compared with it in general efficacy. 
 The soluble and saline matters it contains are made up from 
 the constituents of the food w^e eat ; of course, it contains 
 most of those elementary substances which are necessary 
 to the growth of the plants on which we live. The disa- 
 greeable smell of night-soil may be destroyed by quick 
 lime. If exposed to the air in thin layers strew^ed over 
 with lime, in fine weather, it speedily dries, is easily pul- 
 verized, and, in this state, may be used in the same manner 
 as rape-cake, and delivered into the furrow w^ith the seed. 
 If ni2:ht-soil be treated in a proper manner, so as to re- 
 move the moisture it contains, without permitting the es- 
 cape of its ammonia, it may be put into such a form as 
 will allow it to be transported even to great distances. This 
 is already attempted in many places ; and the preparation 
 of human excrements for exportation constitutes not an un- 
 important branch of industry. But the manner in which this 
 is done, is not always the most judicious. In Paris, the ex- 
 crements are preserved in the houses in open casks, from 
 w^hich they are collected and placed in deep pits at Mont- 
 fau^on ; but they are not sold till they have attained a cer- 
 tain degree of dryness by evaporation in the air. But 
 whilst lying inthe receptacles appropriated for them in the 
 houses, the greatest part of their urea is converted into 
 carbonate of ammonia ; lactate and phosphate of ammonia 
 are also formed, and the vegetable matters contained in them 
 putrefy; all their sulphates are decomposed, whilst their sul- 
 phur forms sulphuretted hydrogen. The mass, when dried 
 by exposure to the air, has lost more than half of the nitro- 
 gen which the excrements originally contained ; for the 
 ammonia escapes into the atmosphere along with the water 
 which evaporates; and the residue now consists principally 
 of phosphate and lactate of ammonia, and small quantities 
 of urate of magnesia and fatty matter. Nevertheless, it is 
 still a very powerful manure ; but its value as such would 
 
110 PRODUCTIVE FARMING. 
 
 be twice or four times as great, if the excrements, before 
 being dried, were neutralized with a cheap mineral acid. 
 
 In other manufactories of manure, the excrements, whilst 
 still soft, are mixed with the ashes of wood, or with earth ; 
 both of which substances contain a large quantity of caustic 
 lime, by means of w4iich a complete expulsion of all their 
 ammonia is effected, and they are completely deprived of 
 smell. But such a residue applied as manure, can act only 
 by the phosphates which it still contains ; for all the am- 
 moniacal salts have been decomposed, and their ammonia 
 expelled. In London, night-soil is dried with various 
 mixtures ; while, in other of our large towns, what is 
 called " animalized charcoal " is prepared by mixing and 
 drying night-soil with gypsum and ordinary wood charcoal 
 in" fine powder. In all cases, the excrements of human 
 beings contain more nitrogen than those of any other 
 animal. Berzelius obtained, by the burning of 100 parts 
 of dried excrements, 15 parts of ashes, principally com- 
 posed of the phosphates of lime and magnesia. 
 
 It is quite certain that the vegetable constituents of the 
 excrements with which we manure our fields, cannot be 
 entirely without influence upon the growth of the crops on 
 them ; for they will decay, and thus furnish carbonic acid 
 to the young plants. But it cannot be imagined that their 
 influence is very great, when it is considered that a good 
 soil is manured only once every six or seven years ; that 
 the quantity of carbon thus given to the land corresponds 
 only to 5 per cent, of what is removed in the form of herbs, 
 straw, or grain ; and further, that the rain-water received by 
 a soil contains much more carbon in the form of carbonic 
 acid than these vegetable constituents of animal excrement. 
 The 'peculiar action, then, of solid, as opposed to fluid, 
 animal excrements, is limited to their mor^amc constituents, 
 rather than to the presence of the partially changed vege- 
 table or organized matter which they contain. Horse 
 dung contains a large proportion of such partially altered 
 vegetable matter ; and the reason why night-soil is a more 
 powerful manure, is that, relatively, it contains less vege- 
 
PRODUCTIVE FARMING. Ill 
 
 table matter, while nitrogen is more abundant ; and this, 
 principally, because its weight is materially made up by 
 the liquid excrement, or urine, always forming part of its 
 composition. Now, urine easily putrefies, and yields am- 
 monia largely; and this because of its containing more 
 animal matter than is contained in dung. A horse lives 
 exclusively on vegetables ; and 100 pounds of the urine of 
 a healthy man, (living, of course, partially upon flesh, and 
 partly upon those seeds and parts of plants containing 
 nitrogen, in quantity,) will yield as much nitrogen as 1300 
 pounds of fresh horse-dung, or 600 of cow-dung. We 
 cannot ascribe much of the power of the excrements of 
 cattle, sheep, and horses, to the nitrogen which they con- 
 tain, for the quantity derivable from these vegetable feeders 
 is too minute. The restoration of inorganic matter to thd 
 land, is the cAie/" value arising from the application of the 
 dung of cattle. A certain amount of inorganic matter is 
 removed with every crop. If we manure that land with 
 the dung of the cow or sheep, we restore to the surface 
 silicate of potash, and some salts of phosphoric acid. If 
 we use horse-dung, we supply, chiefly, phosphate of mag- 
 nesia and silcate of potash. In the straw which has 
 served as litter, we add a further quantity of silicate of 
 potash, and phosphates, which, if the straw be already 
 putrefied, are exactly in the same state as before they 
 formed part of the crop w^hich yielded them. 
 
 But, if we use human excrements, in addition to the 
 phosphates of hme and magnesia, we supply a larger pro- 
 portion of compounds of nitrogen, essential to the develop- 
 ment of those parts of plants upon which human beings are 
 accustomed to feed : and, by a WMse ordination, corn-plants 
 are found associated with human dwellings, — in other 
 words, the family of man having selected such spots on the 
 earth's surface, as are fltted for the growth of corn, animal 
 manure is always at hand in quantity for its artificial culti- 
 vation ; thus restoring, through the feculent discharges of 
 man and animals resident on the spot, precisely those mate- 
 rials which the process of grow^th has removed from the soil. 
 
112 PRODUCTIVE FARMING. 
 
 Cow-dung is not incorrectly said to be "cold:'^ so 
 much of the sahne, nutritive, and other organic matters 
 from the cow, pass off almost exclusively with her urine, 
 that her dung does not readily heat and run into putrefac- 
 tion. Still, mixed with other manures, or well diffused 
 through the soil, its vegetable matter is not useless. It 
 loses more than any other similar substance in drying. The 
 dung of pigs is soft and cold, like that of the cow; contain- 
 ing, like it, nearly 80 per cent of water. Mixed with other 
 manures, it may be applied to any crop ; but is of very 
 variable quality, owing to the variety of food of the animal. 
 
 The horse is fed, generally, on less liquid food, less 
 succulent and watery than that of oxen. He discharges 
 less urine, — hence his dung is richer in animalized matter : 
 or, adopting the figurative language of the farmer, it is 
 hotter, and, indeed, runs more readily into the putrefactive 
 fermentation. 
 
 If the solid excrements of animals are chiefly valuable 
 for the saline, earthy, and inorganic constituents they re- 
 store to the soil which has yielded them, it will be readily 
 inferred, that instead of dung or night-soil, other substan- 
 ces, containing their peculiar ingredients, may be substi- 
 tuted. One hundred tons of fresh horse-dung, if dried, 
 would leave only from 25 to 30 tons of solid matter, the 
 rest being only water ; and if this dried matter (itself only 
 one-fourth of the original weight) were burnt, so as to 
 decompose its vegetable ingredients, we should obtain, per- 
 haps, 10 per cent, of really useful saline and earthy matters, 
 (one-fortieth of the original weight,) according to the rich- 
 ness or poverty of the food the horse had taken. 
 
 Now, this minute proportion of saline and earthy mat- 
 ters, and its relative quantity, in the various kinds of dung 
 or excrement, forms, evidently, the chief topic of interest to 
 which our attention should be directed ; inasmuch as what 
 is left upon such examination and analysis, is exactly what 
 has made up the component inorganic parts of the hay, 
 straw, grass, or oats, on which the animal has been fed; 
 or, in other words, exactly what has been removed from the 
 
PRODUCTIVE FARMING. Il3 
 
 soil, and requires to be replaced, if the next crop is to equal 
 the last. If our object is increased fertility, more must be 
 added than has been taken away. Hay, straw, and oats, 
 formed (for illustration' sake) the food of a horse. Their 
 principal constituents are the phosphates of lime and mag- 
 nesia, carbonate of lime, and silicate of potash ; the first 
 three of these preponderated in the corn, the latter in the 
 hay, and these, removed from the soil with the crop, are 
 precisely the saline matters which would be found in the 
 excrement of the animal for whose support that crop was 
 intended. 
 
 In order, then, to atone for the absence of that excre- 
 ment which derives its value from the soil which has pro- 
 duced it, and for which it is peculiarly fitted, as containing 
 what that soil has lost, the ashes oficood or hones may often 
 be judiciously substituted ; and for this reason ; wood- 
 ashes contain silicate of potash, exactly in the same propor- 
 tion as that salt is found to exist in the straw of the last 
 crop; and as to hones, the greatest part of their bulk con- 
 sists of the phosphates of lime and magnesia. Ashes ob- 
 tained from various trees are of unequal value : those from 
 oak-wood are the least, those from beech most serviceable. 
 With every 100 pounds of the ashes of the beech spread over 
 a soil, we furnish as much phosphates as 460 pounds of fresh 
 night-soil could yield. But night-soil contains other useful 
 matters besides phosphates ; hence the utility of mixed com- 
 posts, as, evidently, the ashes of the beech would not alone 
 secure fertility. 
 
 Bone manure possesses still greater importance ^than 
 wood ashes as a substitute for an indefinite and large sup- 
 ply of animal excrement. The primary sources from. which 
 the bones of animals are derived are, — the hay, straw, or 
 other substances which they take as food. Now, bones 
 contain more than half their weight of the phosphates of 
 lime and magnesia ; and hay contains as much of these 
 salts as wheat straw. It follows, then, that 8 pounds of 
 bones contain as much phosphate of lime as 1000 pounds 
 of hay or wheat straw; and 2 pounds of bones as much 
 
 6* 
 
114 PRODUCTIVE FARMING. 
 
 as is found in 1000 of the grain of wheat or oats. These 
 numbers express pretty exactly the quantity of 'phosphates 
 "which a soil yields annually on the growth of hay and corn. 
 Upon every acre of land appropriated to the growth of 
 wheat, clover, potatoes, or turnips, forty pounds of bone- 
 dust will be found sufficient to furnish an adequate supply 
 oi phosphates for three successive crops. 
 
 To secure the best application of bones, they should be 
 reduced to powder; and the more intimately they are mix- 
 ed with the soil, the more easily are they taken up and 
 assimilated. The most easy and practical mode of efiiscting 
 this, is to pour over the bones, in powder, half their weight 
 of sulphuric acid, (or oil of vitriol,) diluted with three or 
 four parts of water; and after they have remained in con- 
 tact for some time, say a fortnight, to add one hundred 
 parts of w^ater, and sprinkle this mixture over the field be- 
 fore the plough. Bones may be preserved unchanged, lor 
 thousands of years, in dry, or even in moist soils, provided 
 the access of rain be prevented, as is exemplified by the 
 bones of animals, buried previous to the flood, lound in 
 loam or gypsum ; the interior parts being protected by the 
 exterior from the action of water. But they become warm 
 when reduced to a fine powder ; and moistened bones 
 generate heat, and enter into putrefaction ; — the gelatine 
 which they contain is decomposed, and its nitrogen con- 
 verted into carbonate of ammonia, and other ammoniacal 
 salts, which are retained, in a great measure, by the powder 
 itself. Bones burnt till quite white, and recently heated to 
 redness, will absorb seven times their volume of ammonia- 
 cal gas. The analysis of bone enables us to say, that while 
 100 pounds of bone-dust add to the soil 33^of gelatine, the 
 organized substance of horn, or as much organized matter 
 as is contained in 300 or 400 pounds of blood or flesh, they 
 add, at the same time, more than half their weight of iiior- 
 ganic matter, lime, magnesia, soda, common salt, and phos- 
 phoric acid, in combination with some of these ; — all ^of 
 which, as we have seen, must be present in a fertile soil, 
 since the plants require a certain supply of them all at 
 
PRODUCTIVE FARMING. 115 
 
 every period of their growth, but more especially during 
 the maturation of the straw and grain. These substances, 
 like the inorganic matter of plants ploughed into the soil, 
 may, and do exert a beneficial agency upon vegetation after 
 all Ihe organized structure of such decaying plants is bro- 
 ken up and destroyed. One hundred parts of dry bones 
 contain 33 per cent, of dry gelatine, and are equivalent to 
 250 parts of recent human urine. We do not speak now 
 of the bone-dust w^hich remains after all the animal gela- 
 tine is removed, in boiling them to extract size for the 
 calico-printer. 
 
 Horn is a still more powerful manure than bone, — that 
 is to say, it contains a greater proportion of organized ani- 
 mal matter. The peculiarity is, that horn, hair, and wool, 
 as organized substances, are dry ; while blood and flesh 
 contain from 80 to 90 per cent, their w^eight of water. 
 Hence, a ton of horn-shavings, of hair, or of dry woollen 
 rags, ought to enrich the soil with as much animal matter, 
 (and consequently nitrogen,) as would be yielded by ten 
 tons of blood. In consequence of this dryness, horn and 
 wool decompose more slowly than blood ; and hence, the 
 effect of soft animal matters is more immediate and appar- 
 ent than that of hard and dry animal matters, the action 
 of which is, nevertheless, stronger, and continues for a 
 longer period. 
 
 The refuse of the different manufactories of skin and 
 leather form very useful animal manures; such as the shav- 
 ings of the currier, furrier's clippings, and the offals of the 
 tan-yard and of the glue-maker. The gelatine contained 
 in every kind of skin is in a state fitted for its gradual de- 
 composition ; and when buried in the soil, it lasts for a 
 considerable time, and constantly affords a supply of nutri- 
 tive matter to the plants in its neighbourhood. These ma- 
 nures contain nitrogen as well as phosphates, and, conse- 
 quently, are well fitted to aid the process of vegetable 
 growth. 
 
 From w^hat has been stated, we may arrive at the fol- 
 lowing conclusions : — 
 
116 PRODUCTIVE FARMING. 
 
 1. That fresh human urine yields nitrogen in greater 
 abundance to vegetation than any other material of easy 
 acquisition; and that the urine of animals is valuable for 
 the same purpose, but not equally so. 
 
 2. That the mixed excrements of man and animals 
 yield, (if carefully preserved from further decomposition,) 
 not only nitrogen, but other invaluable saline and earthy 
 matters that have been already extracted in food from the 
 soil. 
 
 3. That animal substances which, like urine, flesh, and 
 blood, decompose rapidly, are fitted to operate immediately 
 and powerfully on vegetation. 
 
 4. That d7'y animal substances, as horn, hair, or wool- 
 len rags, decompose slowly, and (weight for weight) con- 
 tain a greater quantity of organized as w'ell as unorganized 
 materials, manifesting their influence it may be for several 
 seasons. 
 
 5. That bones, acting like horn, in so far as their ani- 
 mal matter is concerned, and like it for a number of sea- 
 sons more or less, according as they have been more or less 
 finely crushed, may ameliorate the soil by their earthy mat- 
 ter for a long period, (even if the jelly they contain have 
 been injuriously removed by the size maker,) permanently 
 improving the condition and adding to the natural capabili- 
 ties of the land. 
 
 CHAPTER IX. 
 
 Of the comparative Value of Vegetable Manure, as contrasted with 
 Animal Excrements. 
 
 It may be asked, if the principal sources of the nitro- 
 gen required for the artificial forcing of corn-plants be the 
 feculent excretions of man and animals, — if the object be 
 chiefly to replace in the soil those matters which have been 
 abstracted with the previous crop, — how is it that such ex- 
 crements more eflfectually restore those elements, than would 
 
PRODUCTIVE FARMING. 117 
 
 occur if the ripe crop were ploughed into the soil ; in other 
 words, how is it that dung and urine are richer in nitrogen 
 than the food from which they are formed ? 
 
 The answer is easy and obvious. The bulk of a vege- 
 table is chiefly woody fibre or carbon. A horse lives ex- 
 clusively upon vegetables, and discharges from his lungs, in 
 breathing, a large portion of the carbon his food contains ; 
 hence, what is left to be thrown off from his kidneys and bow- 
 els, contains re/a^we/y a greater proportion of nitrogen which 
 could only be otherwise feebly supplied to the soil from the 
 rain-water of the atmosphere, while the air yields to the land 
 carbon in abundance. Nearly the whole of the nitrogen con- 
 tained in his food, (indeed, all beyond what is necessary for 
 the wants of his own living system,) is thrown off in his 
 urine and dung. In the food consumed, the carbon was to 
 the nitrogen as 9 to 1 : in that which remains, after breath- 
 ing has done its work, the carbon is to the nitrogen in the 
 proportion of only 2 to 1. It is out of this residue, rich in 
 nitrogen, that the several parts of animal bodies are built 
 up. Warm-blooded animals with capacious lungs, double 
 and triple their weight very rapidly after birth : they take 
 in (as lambs or calves after separation from the parent) 
 only vegetable food ; but the rapidity of its decomposition 
 is the index or ratio of the rapidity of their growth. Their 
 actions are lively; and the playful exertion of their 
 muscles renders the decomposing play of the heart, and 
 consequently of the lungs, more frequent than when fully 
 grown. During their quick growth, they ahsorh all the 
 nitrogen their food contains, while they throw off car- 
 bon from the lungs. After growth is finished, they still 
 throw off, in breathing, nearly all the carbon, while the re- 
 sidual quantity of nitrogen (not wanted for the purposes of 
 the living system) escapes in the dung and urine. The 
 urine of a child would not, upon putrefaction, disengage the 
 same quantity of ammonia as that of a full-grown man. 
 Hence the reason why bodies can be nourished and built up 
 upon food comparatively poor in nitrogen ; and yet not 
 only do those same bodies contain nitrogen in quantity, but 
 
118 PRODUCTIVE FARMING. 
 
 also their excretions are rich in the same element. The 
 more nitrogen that is appropriated by growing cattle, the 
 less will pass off into the fold-yard ; hence it is natural to 
 expect that the manure, either liquid or solid, w^hich ac- 
 cumulates where many young animals are fed, will not be 
 so rich as that yielded by full-grown cattle, unless, by 
 giving richer food to the young cattle than they actually 
 require or can dispose of, the difference to the dung-heap 
 be made up. A little acquaintance, then, with first princi- 
 ples w^ill explain the seeming difficulty, how it is that the 
 dung or urine of animals has a greater fertilizing power 
 than even the whole weight of the food which they have 
 consumed would have, if laid upon the soil. Its carbon 
 has passed through the lungs of animals that have eaten it 
 into the atmosphere : and the soil can always supply itself 
 with sufficient carbon from the decomposition of the car- 
 bonic acid of the air ; while its natural supply of nitrogen 
 for the plants which grow on its surface is limited to the 
 decomposition of the ammonia, and the evolution of nitro- 
 gen from rain-water, — a quantity which, though sufficient 
 for the sustenance of crabs, will not serve for apples ; and 
 we must remember, that corn-plants are not in a state of 
 nature, — wild oats or potatoes are widely different from the 
 same plants under the care and culture of man. The differ- 
 ence between a wild and a cultivated vegetable is not 
 merely an increment of size, but the development of those 
 parts which, though naturally containing nitrogen, contain, 
 proportionally, far less than by artificial culture they may 
 be compelled to take up. 
 
 The doctrine of the proper application of manures from or- 
 ganized substances offers an illustration of an important part 
 of the economy of nature, and of the happy order in which 
 it is arranged. The death and decay of animal substances 
 tend to resolve organized forms into elementary constituents ; 
 and the pernicious effluvia disengaged in the process seem to 
 point out the propriety of burying them in the soil, where 
 they are fitted to become the food of vegetables. The fermen- 
 tation and putrefaction of organized substances in the free 
 
PRODUCTIVE FARMING. 119 
 
 atmosphere are noxious processes : beneath the surface of 
 the ground, they are salutary operations. In this case, the 
 food of plants is prepared where it can be used, and that 
 which would offend the senses and injure the health, if ex- 
 posed, is converted, by gradual processes, into forms of 
 beauty and of usefulness : the stinking gas is rendered a 
 constituent of the perfume of a flower ; and what might be 
 poison, swells the food of animals and man. 
 
 CHAPTER X 
 
 Of Manures of Mineral Origin, or Fossil and Artificial or Chemical 
 Manures ; their Preparation, and the Manner in which they Act. — 
 Of Lime in its Different States ; its Operation as a Manure. — 
 Of Alkalies, and Common Salt, as to their Action upon the 
 Land. 
 
 From w^lat has been already said, a great variety of 
 substances contribute to the growth of plants, and supply 
 the materials of their nourishment. How matters that have 
 once been living are in turn converted into the substance of 
 other living things, may be comprehended ; but it is more 
 difficult to understand those operations by which earthy and 
 saline matters are taken up and consolidated in the fibre of 
 vegetables. 
 
 Sir Humphrey Davy, quoting the experiments of conti- 
 nental chemists who had preceded him, states, on their 
 authority, that different seeds sow^n in fine sand — flour of 
 brimstone, or rust of iron, and supplied only with air and 
 water, produced healthy plants, which by analysis yielded 
 various earthy and saline matters, which either were not 
 contained in the seeds or the material in which they grew ; 
 and hence they and he concluded, that they must have been 
 formed from air or water, in consequence of the agen- 
 cies of the living organs of the plant. 
 
 It would be impossible to pass this interesting fact, 
 
120 PRODUCTIVE FARMING. 
 
 without observing how strikingly it confirms the views ad- 
 vanced in the preceding pages as to the origin of nitrogen 
 from the ammonia in rain-water. Sir Humphrey contends, 
 from some subsequent experiments, that the atmosphere 
 yields no saline matter to plants; but the existence of am- 
 monia in rain-water, if not unknown to that distinguished 
 chemist, w^as overlooked in his computation. 
 
 The only substances that can, with propriety, be called 
 fossil manures, and which are found unmixed with the re- 
 mains of any organized beings, are certain alkaline earths, 
 or alkalies, and their combinations. 
 
 The only alkaline earths which have been hitherto ap- 
 plied in this way, are lime and magnesia. Potash and so- 
 da, the two fixed alkalies, are both used in certain of 
 their chemical compounds, but never in a pure or caustic 
 state. 
 
 The most common form in which lime is found on the 
 surface of the earth, is in a state of combination with car- 
 bonic acid. We have already alluded to some of its che- 
 mical properties in a previous section of this work. When 
 common limestone is burnt in the kiln, the carbonic gas is 
 driven oft" by the heat, and nothing remains but the pure 
 caustic earth. If the fire have been very high, it approaches 
 to one-half the weight of the stone; but, in common cases, 
 limestones, if well dried before burning, do not lose much 
 more than from 35 to 40 per cent., or from 7 parts to 8 out 
 of 20. 
 
 Very few limestones, or chalks, consist entirely of lime 
 and carbonic acid. Statuary marble is nearly a pure 
 carbonate of lime. When a limestone does not copiously 
 effervesce in acids, and is yet sufficiently hard to scratch 
 glass, it contains the earth of flint, and, probably, the earth 
 of clay. When brownish or yellowish-red, the tinge, in 
 all probability, depends upon the presence of iron. If not 
 hard enough to scratch glass, if the stone effervesce slowly 
 or but slightly with acids, and the solution have a milky 
 appearance, — most probably magnesia is present. 
 
 Before any opinion can be formed of the manner in 
 
PRODUCTIVE FARMING. 121 
 
 which the different ingredients in limestones modify their 
 properties, and their consequent action upon the soil, it will 
 be necessary to consider the action of pure, or recently burnt 
 caustic lime, when employed for agricultural purposes. 
 
 Quicklime, — in its pure state, whether in powder, or 
 dissolved in minute proportion, in water, — is directly inju- 
 rious to 'plants. Grass may be certainly killed by sprinkling 
 it with lune-water ; but since lime is a necessary ingredient 
 in soils, and an useful addition in many cases, it evidently 
 must be that its combination with carbonic acid — the state 
 in which it is found naturally — is the circumstance which 
 not merely renders it void of causticity, but so far alters its 
 properties, as to exchange injury for advantage. Lime, if 
 pure, and recently burnt, cannot long remain caustic, inas- 
 much as it rapidly attracts sufficient carbonic acid from the 
 atmosphere to reduce it to the state of chalk, or a carbonate; 
 and it is a wise arrangement that it is so, — that it is never 
 found, in nature, pure or free from this acid. 
 
 Nevertheless, there are cases in which the application 
 of caustic lime may be requisite. If it be mixed with any 
 moist, fibrous, vegetable matter, there is a strong action 
 between the lime and the vegetable fibrin : they form a kind 
 of compost together, of which a part is usually soluble in 
 water. By this kind of operation, lime renders matter 
 which was comparatively inert, nutritive, or, at least, solu- 
 ble ; and as charcoal and oxygen abound in all plants, the 
 lime becomes at the same time usefully converted, even by 
 their agency, into a carbonate. It is obvious, then, that 
 the operation of quicklime, and that of marl or chalk, 
 depends upon principles altogether different. Quicklime, 
 in being applied to land, tends to bring any hard vegetable 
 matter that it contains into a more rapid and easy state of 
 decomposition ; while chalky forms of lime only add the 
 necessary amount of this earth, so as to furnish the requisite 
 supply to be absorbed as part of the inorganic structure of 
 the plants which grow in that spot. Quicklime, when it 
 becomes mild by exposure, acts in the same way as chalk, 
 
122 PRODUCTIVE FARMING. 
 
 but, in the act of becoming mild, it prepares soluble out of 
 insoluble matter. 
 
 It is upon this circumstance that the operation of lime 
 in the preparation for wheat crops depends, and its efficacy 
 in fertilizing peats, and in brincring into a state of culti- 
 vation all soils abounding in hard roots, dry fibres, or unde- 
 composed and, therefore, useless vegetable matter. 
 
 So, then, the solution of the question. Whether quick- 
 lime ought to be applied to a soil ? depends upon the quan- 
 tity of the undecomposed vegetable matter that soil con- 
 tains; and the answer to the question. Whether marl, or 
 any chalky carbonate of lime, ought to be applied 1 evi- 
 dently depends upon whether the previous crops have 
 exhausted the requisite quantity of lime necessary to form 
 part of the inorganic material of the crop that is intended 
 to be raised there. All soils are improved by mild lime, 
 because each successive crop takes a portion of lime away. 
 But, perhaps, one of the most important and influential 
 agencies of lime in soil to which it is added, is to be found 
 in its ready combination with 7iitric acid, which it assists 
 in forming, from the facility with which it promotes the 
 union of its already existing e]einenis, nitrogemnd oxygen. 
 Nitrate of lime, which, by a series of inevitable actions, 
 is produced in the decomposing soil, is very soluble in 
 water: entering readily into the roots of plants, it forms the 
 medium by which lime becomes part of a vegetable, (for, 
 as before stated, the earths and alkalies never enter a 
 plant in a pure, free, caustic, or uncombined state,) and 
 producing upon growth effects precisely similar to those of 
 the now weW-known nitrate of soda. Ploughing, harrow- 
 ing, digging, and turning over the soil to the action of the 
 air, is useful, chiefly, because it facilitates the more ready 
 action of the atmosphere, indispensable to the formation of 
 these nitrates. 
 
 Besides pure, or caustic lime, and its carbonate, in the 
 form of chalk or marl, the application of gypsum, or sul- 
 phate OF LIME, — sometimes called alabaster, or plaster of 
 Paris, — deserves a passing notice. Great difference of 
 
PRODUCTIVE FARMING. 123 
 
 opinion has prevailed among agriculturists as to its use. 
 Correct notions as to the nature of vegetable growth, an 
 exact acquanitance with the constitution of plants intended 
 to be raised upon a given locality, and the admitted neces- 
 sity for an equally exact acquaintance with the existing 
 condition of that soil, so as to adapt the one to the other, — 
 in fact, a better knowledge of agricultural chemistry, — is 
 all that alone is wanting, or can solve the variety of opinion 
 as to its employment. Plaster of Paris has been advan- 
 tageously used in England, and various testimonies as to its 
 utility have been laid before the Board of Agriculture. 
 Doubtlessly, if lime be deficient in a soil, though marl, or 
 the carbonate, is more easily susceptible of action, the sul- 
 phate or gypsum, which is less so, less easily decomposed, 
 is better than none. Sulphuric acid has a stronger affinity 
 for lime than carbonic acid can exert; hence, gypsum does 
 not so readily enter into new combinations. It has been 
 said, that sulphate of lime assists the putrefactive decom- 
 position of animal substances, — that it hastens the evolution 
 of ammonia, and the consequent development of nitrogen ; 
 but the experiments of Sir Humphrey Davy disprove this 
 view of the case. It would appear that peat-ashes natu- 
 rally contain gypsum in abundance. These peat-ashes are 
 used with advantage in some parts of the country, as a top- 
 dressing for cultivated grasses, particularly clover; and, 
 in examining the ashes of sainfoin and clover, they have 
 been found to contain gypsum in quantity, proving that 
 lime, in the form of a sulphate, is a necessary ingredient in 
 the constitution of some vegetables. The practical deduc- 
 tion from such investigations obviously is, that if clover be 
 intended to be raised upon a soil deficient of lime, in the 
 form of a sulphate, gypsum will not only constitute an ad- 
 vantageous manure, but one that is absolutely. essential to 
 the production of a vigorous, abundant, and healthy crop. 
 Phosphate of lime is another combination of this earth 
 with an acid. It forms the greatest part of calcined bones, 
 of the utility and application of which we have already 
 spoken. It exists in most excreraentitious substances, and 
 
124 PRODUCTIVE FARMING. 
 
 is an essential constituent of the straw and grain of wheat, 
 barley, oats, and rye, and likewise in beans, peas, and 
 vetches. It exists in some places, in these islands, native, 
 but only in small quantities. Phosphate of lime is general- 
 ly conveyed to the land in the composition of other manure, 
 and is absolutely necessary to corn crops. Bone-ashes, 
 ground to powder, are useful on arable land that is defi- 
 cient in lime, or its phosphate, especially if there be a su- 
 perabundance of vegetable matter. If lime, or its phosphate, 
 be the only deficient ingredient in the land, — if it already 
 contain, or be at the same time supplied with animal ma- 
 nure, yielding nitrogen, — then bone-dust may prove useful. 
 
 Wood-ashes consist principally of the vegetable alkali, 
 or potash, united to carbonic acid ; and as this alkali is 
 found in almost all plants, it is not difficult to conceive that 
 it may form an essential part of their organs. The general 
 tendency of the alkalies applied as manure is, to supply the 
 deficiency occasioned by what is removed with the previous 
 crops. Wood-ash contains not only carbonate of potash, 
 but also the sulphate of potash and silicate of potash ; 
 hence its utility, as affording silex to wheat straw, — a ma- 
 terial essential to its firmness and stability. These saline 
 matters in wood-ash are all valuable, as supplying the ne- 
 cessary inorganic constituents of plants ; and hence the ex- 
 tensive use of wood-ash, as a manure, in every country 
 where it can readily be procured. 
 
 Peat-ashes vary, in constitution, with the kind of peat 
 from which they have been prepared. They often contain 
 traces of potash and soda, and generally a quantity of sul- 
 phate and carbonate of lime, a trace of phosphate of lime, 
 and much siliceous matter. In almost every country where 
 peat abounds, the value of peat-ashes, as a manure, has 
 been more or less generally recognised. 
 
 Kelp. The ash left by the burning of sea-weed con- 
 tains potash, soda, silica, sulphur, and several other of the 
 inorganic constituents of plants, and is usefully and exten- 
 sively employed in many districts near the sea, where plants 
 naturally requiring these materials grow more luxuriantly 
 
PRODUCTIVE FARMING. 125 
 
 than in more inland districts. Sea-weeds decompose with 
 great rapidity when collected in heaps and laid upon the 
 land. During their decay, they not only yield inorganic 
 saline matter to the soil, but enrich it with an additional 
 layer of vegetable mould. 
 
 JVitrate of soda, and nitrate of 'potash or saltpetre. 
 These substances have been much commended for their be- 
 neficial action upon growing plants. They impart to the 
 leaves a deeper green, and evidently quicken vegetable 
 action : they are applied advantageously to grass and young 
 corn, at the rate of a hundred weight of either to an acre. 
 The nitric acid they contain yields the additional nitrogen 
 beyond the quantity the plants can obtain by decompos- 
 ing the ammonia contained in the rain that falls upon 
 them ; at the same time, the other ingredient — potash or 
 soda, as the case may be — is put within the reach of their 
 roots, to be absorbed as an inorganic, yet necessary con- 
 stituent. 
 
 Commoji salt, muriate of soda, or, more correctly, a 
 compound of the metal sodium with elementary chlorine, 
 is undoubtedly indispensable to the fertility of many inland 
 soils. It is not without design that the spray of the sea is 
 allowed to be borne by the winds for many miles over the 
 shore, so supplying an ample dressing of common salt to 
 the land. A minute quantity is absolutely necessary to the 
 healthy growth of all our cultivated crops, and most lands 
 (in this island at least) contain a sufficient quantity of it 
 for the purposes of vegetation. Common salt is found in 
 every species of animal manure, and will be found most 
 requisite in high situations exposed to the washing of heavy 
 rains, which tend to remove the soluble alkaline matters 
 from the soil. Much diversity of opinion has prevailed as 
 to the utility of this substance. The Cheshire farmers plead 
 in its favour. On the other hand, that salt in large quan- 
 tities, renders land barren, was known long before any 
 records of agricultural science existed. We read in Scrip- 
 ture, that Abimelech took the city of Shechem, and sowed 
 he land with salt, that the spot might be forever unfruit- 
 
126 PRODUCTIVE FARMING. 
 
 ful. Pliny, a Latin historian, though he recommends giv- 
 ing salt to cattle, yet affirms, that when strewed over land 
 it renders it barren. But these form no argument against 
 the proper application of it. There can be no question 
 that salt, as well as many other similar mineral substances, 
 are really useful to vegetation ; yet the intelligent agricul- 
 turist ought not to be surprised to find, that a substance 
 which is useful, because necessary and deficient in one in- 
 stance, may be positively in excess, and consequently inju- 
 rious, if added in another. He will try cautiously, and 
 upon a small scale, whether this or that materia] seems 
 fitted to answer his intention ; or, what is far better than 
 blind hit-or-miss experiment, he will endeavour to ascer- 
 tain the actual constitution of the soil, and not expect to 
 grow wheat where there is no phosphate of lime or silicate 
 of potash ; nor plants which thrive best near the sea, in a 
 soil which he knows to be devoid of common salt. If salt 
 be there, it is a needless and foolish waste to attempt to 
 improve the land by adding more. If he has already bricks 
 enough at hand, you must carry the builder mortar : more 
 bricks will not supply the place of mortar. So, if the soil 
 contain lime, or magnesia, or potash, in sufficient abun- 
 dance for the wants of the plant it is our object artificially 
 to force, it may still be deficient of other materials ; and 
 here the skill and science of one man stand in beautiful 
 contrast with the blundering, bungling guesses of another. 
 At a meeting of the Chemical Society, a paper was lately 
 read, containing a report of some experiments with saline 
 manures containing nitrogen, conducted on the Manor Farm, 
 Havering-atte-Bower, Essex, in the occupation of C. Hall, 
 Esq., communicated by W. M. F. Chatterley, Esq. The exper- 
 iments were suggested by the prevailing opinion, that the fer- 
 tilizing power of some animal manures, and of the salts, 
 nitre, (nitrate of potash,) nitrate of soda, and sulphate of 
 ammonia, depend upon the proportion of nitrogen they 
 contain. The salts mentioned are all, from their low price, 
 within the reach of the farmer; and the quantity of the last 
 thrown into the market is greatly increasing, from the ex- 
 
PRODUCTIVE FARMING. 127 
 
 tension of the new mode of purifying coal-gas from its 
 ammonia, by washing the gas with diluted sulphuric acid. 
 The interest also of expeiiments with salts is greater than 
 with mixed manures, both to the farmer, who, from the 
 nature of the former substances, may depend upon their 
 uniformity, and to the chemist, as their composition is ne- 
 cessarily known to him. A field of wheat was chosen, 
 which, in the latter end of April, 1842, presented a thin 
 plant; the salts were top-dressed over the land by hand, 
 on the 12th of May, and the crop mowed on the 10th of 
 August. The soil was rather poor, consisting of a heavy 
 clay upon a subsoil of the London clay. 1. No manure ; 
 corn per acre 1413 lbs. 2. With 28 lbs. of sulphate of 
 ammonia; corn, 1612 lbs. 3. With 140 lbs. of the same 
 salt; corn, 1999 lbs. 4. With 112 lbs. of nitrate of soda ; 
 corn, 1905 lbs. 5. With 1 12 lbs. of nitre ; corn, 1890 lbs. 
 The increase in the straw was also considerable in all 
 cases, except with the small proportion of sulphate of am- 
 monia. The total increase in the four manured crops was 
 per cent., in the order in which they were enumerated, — 
 14.1,41.5, 34, and 33.5. The cost of the manure for the 
 three last did not greatly differ, being 21s. 9d., 24s. 6d., 
 27s. 6d. ; and the profit on the outlay was, with the small 
 dose of sulphate of ammonia, 294 per cent. ; with the large 
 dose, 212 per cent. ; with the nitrate of soda, 138 per cent. ; 
 and with the nitrate of potash, 92 per cent. The princi- 
 pal conclusions drawn by the author are, that the increase 
 of nitrogen in the crop is greater than is accounted for by 
 the nitrogen of the manures, showing that these manures 
 have a stimulating effect, or enable the plants to draw ad- 
 ditional nitrogenized food from the soil and atmosphere ; 
 the considerable superiority of sulphate of ammonia over 
 the other salts, and the greater proportional efficiency of a 
 small, than of a large dose of that salt. The sulphate of 
 ammonia costs 17s. per cwt. It appears best to apply this 
 salt in the proportion of about 1 cwt. per acre, at three 
 different dressings : the first quantity when the crop of 
 wheat makes its spring growth, or if of oats, when about 
 
128 PRODUCTIVE FARMING. 
 
 two inches above the ground ; the second quantity about 
 a month afterwards ; and the third at the time of the for- 
 mation of the ear. To meet the practical difficulty of dis- 
 tributing so small a quantity as one-third of a hundredweight 
 over an acre, about twice the quantity of common salt or 
 of soot may be mixed with the ammoniacal salt. These, 
 and most saline manures, when used as a top-dressing, 
 should be supplied to the plant when dry, after a shower of 
 rain, or during hazy weather. 
 
 That which was true in the day of Sir Humprey Davy, 
 when experimental agricultural chemistry was in its infancy, 
 is equally true at the present moment. He observes that 
 " much of the discordance of the evidence relating to the 
 efficacy of saline substances depends upon the circumstance 
 of their having been used in varying proportions, and in 
 general in quantities much too large." That which is sal- 
 utary and medicinal in moderate doses, not only may be, 
 but is absolutely poisonous in another. 
 
 Sir Humphrey made a number of experiments on the 
 effects of different saline substances on barley and on 
 grass growing in the same garden, the soil of which 
 was a light sand, of which 100 parts were composed of 
 60 parts of siliceous sand, and 24 parts finely-divided 
 matter, consisting of 7 parts carbonate of lime, 12 parts 
 alumina and silica, less than one part saline matter, prin- 
 cipally common salt, with a trace of gypsum and magne- 
 sia ; the remaining 16 parts were vegetable mould. The 
 solutions of the saline substances were used twice a week, 
 in the quantity of two ounces, on spots of grass and corn, 
 sufficiently distant from each other to prevent any inter- 
 ference of results. Several of the salts of potash, soda, 
 magnesia and ammonia were experimentally and separ- 
 ately employed. He found that in all cases, when the 
 quantity of the salt equalled one-thirtieth part of the weight 
 of the water, the effects w^ere injurious ; but least so with 
 the salts of ammonia. When the quantities of the salts 
 were one part in three hundred of the solution, or 1 pound 
 to 300 pounds of water, the effects were different. Those 
 
PRODUCTIVE FARMING. 129 
 
 spots watered with the solution of carbonate of ammonia 
 were most luxuriant of all. This last result is what might 
 be expected, (and it agrees well with the theoretic views 
 of later chemists,) inasmuch as carbonate of ammonia is 
 made up of carbon, oxygen, hydrogen, and nitrogen : all 
 of which are essential to the supply of the additional quan- 
 tities artificial plants require beyond that they can naturally 
 obtain from the surrounding atmosphere. He observes that 
 the solution of nitrate of ammonia seemed to be of no 
 greater use than rain-water, and he attributes its failure to 
 the circumstance of the acid being in excess. But Sir 
 Humphrey was not aware that rain-water actually contains 
 ammonia ; it was left to the genius of Liebeg, in our later 
 day, to develope that discovery. 
 
 CHAPTER XI. 
 
 Of the Composition of Productive Soils, and of the Agency of the 
 Elements in their Natural Formation, from the Rocks upon which 
 they rest. 
 
 We may now take it for granted that every' practical 
 farmer will admit the position as proved, namely, that 
 there must be an exact adaptation and fitness between the 
 condition of any given soil and the plants intended to be 
 raised upon it : and that, if this condition does not exist 
 naturally, it not only may be, but must be, artificially 
 remedied. 
 
 At this stage of the inquiry, it will be our endeavour to 
 anticipate further question, and to give an exact account of 
 the chemical constitution of such soils as are known to be 
 best suited to the cultivation and growth of green as well 
 as corn crops. 
 
 There are in existence as many varieties of soils as 
 there are species of rocks exposed at the surface of the 
 
 7 
 
130 PRODUCTIVE FARMING. 
 
 earth. In fact, there are many more. Independently of 
 the changes produced by cultivation and the exertions of 
 human labour in tearing down and breaking up the sur- 
 face, the materials of various layers have been mixed to- 
 gether and carried from place to place by various great al- 
 terations that, during a succession of ages, have been si- 
 lently yet constantly carried forward in the system of our 
 globe, together with the united agencies of air, water, 
 and the varying alternations of summer's heat and the 
 cold of winter. 
 
 It may not be improper here to give a general descrip- 
 tion of the geological constitution of Great Britain and Ire- 
 land. It will be impossible to avoid the use of some names 
 which scientific men have imposed upon the various rocks; 
 and indeed, if we could offer the names by which they are 
 vulgarly and popularly known in each district, it is proba- 
 ble they would be equally unintelligible in distant parts of 
 the country. From these rocks are formed, by the action 
 of the elements, the various soils which support vegetation. 
 Granite forms the great ridge of hills extending through 
 Cornwall and Devonshire. Tiie highest rocks in Somer- 
 setshire are limestone and grauwacke. The Malvern hills 
 are composed of granite, sienite, and porphyry. The high- 
 est mountains in Wales are chlorite, schist, or grauwacke. 
 Granite occurs at Mount Sorrel in Leicestershire. The 
 great range of mountains in Cumberland and Westmore- 
 land are porphyry, chlorite, schist, and grauwacke ; but 
 granite occurs at their western boundary. Throughout 
 Scotland the most elevated rocks are granite, sienite, and 
 micaceous schist. No true secondary formations are found 
 in South Britain, and no basalt south of the Severn. The 
 chalk district extends from the western part of Dorsetshire 
 to the eastern coast of Norfolk. The coal formations 
 abound in the district between Glamorganshire and Derby- 
 shire, and likewise in the secondary strata of Yorkshire, 
 Durham, Westmoreland, and Northumberland. Serpentine 
 is found only in three places in Great Britain : in Cornwall, 
 Aberdeenshire, and Ayrshire. Black and gray marble is 
 
PRODUCTIVE FARMING. 131 
 
 found in Cornwall, and other coloured primary marbles 
 exist in the neighbourhood of Plymouth. Coloured prima- 
 ry marbles are abundant in Scotland. The principal coal 
 formations in Scotland are in Dumbartonshire, Ayrshire, 
 Fifeshire, and in Sutherland. Secondary limestone and 
 sandstone are found in most of the low countries north of 
 the Mendip hills. 
 
 In Ireland there are five great associations of primary 
 mountains ; the mountains of Morne in the county of Down ; 
 the mountains of Donegal ; those of Mayo and Galway ; 
 those of Wicklow and those of Kerry. Who does not re- 
 member the words of the song, — 
 
 " The Wicklow hills are very high, 
 And so's the hill o' Howth, Sir." 
 
 The rocks composing the first four of these mountain-chains 
 are principally granite, gneiss, sienite, schist, and porphy- 
 ry. The mountains of Kerry are chiefly constituted by 
 granular quartz, and chlorite schist. Coloured marble is 
 found near Killarney, and white marble on the west coast 
 of Donegal. Limestone and sandstone are the common 
 secondary rocks found south of Dublin. In Sligo, Roscom- 
 mon, and Leltrim, limestone, sandstone, shale, iron-stone, 
 and bituminous coal are found. The northern coast of Ire- 
 land is principally basalt ; this rock commonly reposes on 
 a white limestone, containing layers of flint, and the same 
 fossils as chalk ; but it is considerably harder than that 
 rock. The stone-coal of Ireland is principally found in Kil- 
 kenny, associated with limestone and grauwacke. 
 
 To attempt to class soils with scientific accuracy would 
 be a needless labour ; the distinctions adopted by farmers 
 are sufficient for our present purpose, particularly if some 
 degree of exactitude be maintained in the application of 
 terms. A full knowledge of modern geology is not neces- 
 sary to enable a man to determine whether a field is best 
 suited for arable or grazing purposes ; nor is it our inten- 
 tion needlessly to employ the scientific appellations which 
 would only puzzle because they are incomprehensible to 
 
132 PRODUCTIVE FARMING. 
 
 minds unfamiliar with geological nomenclature. The ex- 
 pression " a sandy soil,'^ is well understood ; but let it ne- 
 ver be applied to any soil that does not contain at least 
 three parts out of four of sand. Then, again, sandy soils 
 that effervesce or give off carbonic acid, or fixed air, when 
 vinegar or vitriol is poured upon them, should be distin- 
 guished by the name of " sandy limestone soils,'' to mark 
 them from sandy soils that contain silex or the earth of 
 flint. The term " clayey soil,'' should not be applied to 
 any land which contains less than one-sixth of an earthy 
 matter not effervescing with acids; while the word " loam" 
 should be limited to such soils as contain one-third of a 
 smooth earthy matter, considerably effervescing with acids. 
 A soil to be considered " peaty" ought to contain at least 
 one-half of vegetable matter. 
 
 Soils perform at least three functions in reference to 
 vegetation. They serve as a basis in which plants may fix 
 their roots and sustain themselves in the erect position — 
 they are the medium through which the greater part of the 
 inorganic matter of vegetables is supplied to them during 
 their growth — and they allow many chemical changes to 
 take place that are essential to a right preparation of the 
 various kinds of food which are yielded to the growing 
 plant. 
 
 The best natural soils are those whence the materials 
 have been derived from the breaking up and decomposition, 
 not of one stratum or layer, but of many — divided minutely 
 by air and water, and minutely blended together : and in 
 improving soils by artificial additions, the farmer cannot do 
 better than imitate the processes of nature. 
 
 We have spoken of soils as consisting mostly of sandy 
 lime, and clay, with certain saline and organic substances 
 in smaller and varying proportions ; but the examination 
 of the ashes of plants shows that a fertile soil must of ne- 
 cessity contain an appreciable quantity of at least eleven 
 diflferent substances, which in most cases exist in greater or 
 less relative abundance in the ash of cultivated plants ; and 
 of these the proportions are not by any means immaterial. 
 
PRODUCTIVE FARMING. 133. 
 
 The labour requisite for the permanent improvement of land 
 is repaid by correspondent advantage : the materials for 
 the necessary adjustment are seldom far distant. If coarse 
 sand be requisite, it is mostly or often found immediately over 
 the chalky soil that needs it; and beds of sand and gravel are 
 common below clay. Capital laid out in this way, secures 
 for ever the productiveness and consequent value of the 
 land. 
 
 In ascertaining the composition of barren soils with a 
 view to their productiveness, or of partially unproductive 
 land, in order to its amendment, they should be compared 
 with fertile soils in the same neighbourhood, and in similar 
 situations ; as the difference of composition will, in most 
 cases, indicate the proper methods of improvement. For 
 instance, if on washing a portion of sterile soil it be found 
 to contain largely any salt of iron, or any acid matter, it 
 may be ameliorated with quicklime, which removes the 
 sourness, or, in other words, combines with and neutralizes 
 the acid. For though pure fresh burnt caustic hme is injuri- 
 ous to vegetation, yet in combination with acids (as in 
 chalk) it proves eminently serviceable. A soil, apparently of 
 good texture, was put into the hands of Sir Humphrey Davy 
 for examination, said to be remarkable for its unfitness for 
 agricultural purposes; he found it contained sulphate of 
 iron, or green copperas, and offered the obvious remedy 
 of top-dressing with lime, which decomposes the sulphate. 
 So if there be an excess of lime, in any form, in the soil, 
 it may be removed by the application of sand or clay. 
 Soils too abundant in sand are benefited by the use of clay 
 or marl, or vegetable matter. To a field of light sand that 
 had been much burnt up by a hot summer, the application 
 of peat was recommended as a top-dressing ; it was attend- 
 ed not only with immediate advantage, but the good effects 
 were permanent. A deficiency of vegetable or animal 
 matter is easily discoverable, and may as easily be supplied 
 by manure. On the other hand, an excess of vegetable 
 matter may be removed by paring and burning, or by the 
 application of earthy materials. The effect of paring and 
 
134 FRODUCTIVC FARMING. 
 
 burning is easily understood. The matted sods consist of 
 a mixture of much vegetable with a comparatively small 
 quantity of earthy matter ; when these are burned, only the 
 ash of the plant is left, intimately mixed with the calcined 
 earth. To strew this mixture over ihe exposed soil is much 
 the same as dressing it with peat or wood-ashes, the bene- 
 ficial effects of which upon vegetation are almost univer- 
 sally recognised. From what has been already said, it will 
 be easily evident, that the beneficial effect of the burnt ash is 
 chiefly owing to the ready supply of inorganic and saline 
 material it yields to the seeds which may afterwards be 
 scattered there ; besides which, the roots of weeds and 
 poorer grasses, if not exterminated by the paring, are so far 
 injured as to lead to their death and subsequent decom- 
 position. 
 
 The improvement of peats or bogs, or marsh lands, must 
 be preceded by draining, stagnant water being injurious to 
 all the nutritive classes of plants. Soft black peats, when 
 drained, are often made productive by the mere application 
 of sand or clay as a top-dressing. The first step to be 
 taken, in order to increase the fertility of nearly all the 
 improvable lands in Great Britain, is to drain the7n. So 
 long as they remain wet they will continue to be cold. 
 Where too much water is present in the soil, that food of 
 the plant which the soil supplies is so much diluted and 
 weakened that the plant is of necessity scantily nourished. 
 By the removal of the superfluous water, the soil crumbles, 
 becomes less s>iff and tenacious, air and warmth gain ready 
 access to the roots of the growing plant ; the access of air 
 (and consequently of the carbonic acid which the atmos- 
 phere freely supplies) being an essential element in the 
 healthy growth of the most important vegetable produc- 
 tions. Every one knows, that when water is applied to the 
 bottom of a flower-pot full of soil, it will gradually find its 
 way to the surface, however light that soil may be ; so in 
 sandy soils or sub-soils in the open field. If water abound 
 at the depth of a few feet, or if it so abound at certain sea- 
 sons of the year, such water will rise to the surface ; and 
 
PRODUCTIVE FARMING. 135 
 
 as the sun's heat causes it to dry off, more water will rise 
 
 to supply its place. This attraction from beneath will 
 always go on most strongly when the air is dry and warm, 
 anfl so a double mischief will ensue: the soil will be kept 
 cold and wet ; and instead of" a free passage of air down- 
 wards about the growing roots, there will be established a 
 constant current of water upwards. Of course, the remedy 
 for all this is an efficient system of drainage. 
 
 In genera], the soils which are made up of the most 
 various materials are those called alluvial^ which have been 
 formed from the depositions of floods and rivers. Many of 
 these are extremely fertile. Soils consist of two parts; of 
 an organic part, which can readily be burned away when 
 the surface-soil is heated to redness ', and of an inorganic 
 part, which remains fixed in the fire, consisting of earthy 
 and saline substances; from which, if carbonic acid, or any 
 elastic gas be present, it may, however, be driven by the 
 heat. The organic part of soils is derived chiefly from the 
 remains of vegetables and animals which have lived and 
 died in and upon the soil, which have been spread over it 
 by rivers and rains, or which have been adfled by the in- 
 dustry of man for the purposes of increased fertility. 
 
 This organic part varies much in quantity, as well as 
 quality, in different soils. In peaty soils it is very abund- 
 ant, as well as in some rich long cultivated lands. In 
 general, it rarely amounts to one-fourth, or 25 per cent., 
 even in our best arable lands. Good wheat soils contain 
 often as little as eight parts in the hundred of organic ani- 
 mal or vegetable matter : oats and rye will grow in a soil 
 containing only 1^ per cent. ; and barley when only two or 
 three parts per cent, are present. In very old pasture-lands, 
 and in gardens, vegetable matter occasionally accumulates 
 so as to be injurious, and overload the upper soil. This 
 decaying vegetable, or animal matter, is the " humus" 
 previously adverted to, and incorrectly supposed, before 
 our day, to afford almost the sole nutriment essentially ne- 
 cessary to growing plants. That living plants derive from 
 the remains of their decayed predecessors the advantage of 
 
136 PRODUCTIVE FAEMING. 
 
 being placed in contact with the inorganic or saline mate- 
 rials those plants once contained, is not to be denied. But 
 unless the whole crop were ploughed in, every year, this 
 quantity would be exceedingly minute. The true value of 
 green crops ploughed into the soil, or of decaying vegeta- 
 ble matter, the " humus" of former writers, is the forma- 
 tion of carbonic acid by the combination of decomposed 
 carbonaceous or woody fibre with atmospheric oxygen ; 
 thus supplying to the new and young roots carbon in a 
 form susceptible of being taken up by them. 
 
 The inorganic portion of any given soil is again divisi- 
 ble into two portions — namely, that part which is soluble 
 in water, and, therefore, in a state easily susceptible of be- 
 ing taken up by the vessels of a growing vegetable, and of 
 a further and much more bulky portion which is insoluble 
 in water. The soluble portion consists of saline substances 
 — the insoluble, of earthy materials. 
 
 A single grain of saline matter in every pound of a 
 soil a foot deep, is equal to 500 pounds in every acre, 
 which is more than is carried off from the land in the course 
 of forty years, supposing that the wheat and barley are 
 sent to market, and the straw and green crops are regularly 
 returned to the soil in the shape of manure. 
 
 Sprengel, a German chemist, now^ at the head of the 
 Prussian agricultural school, whose own taste, as well as 
 his professional duty, have long directed his attention to 
 scientific cultivation of the soil — has published an exact 
 analysis of two varieties of 'productive soil, of which the 
 following is an abstract : 
 
 The first is a very fertile alluvial soil from East 
 Friesland, formerly overflowed by the sea, but for sixty 
 years cultivated with corn and pulse without manure. 
 
 The second is a fertile soil near Gottingen, which pro- 
 duces excellent crops of clover, pulse, rape, potatoes, and 
 turnips ; the two last more especially uhen matured with 
 gypsum. 
 
 One thousand parts of each of these soils, after wash- 
 ing, gave— 
 
PRODUCTIVE FARMING. 137 
 
 
 No. 1. 
 
 No. 2. 
 
 Soluble saline matter, 
 
 18 
 
 1 
 
 Fine earthy and organic matter, (clay) 
 
 . 937 
 
 839 
 
 Siliceous sand, .... 
 
 45 
 
 160 
 
 1000 1000 
 
 The most striking distinction presented by these numbers is 
 the large quantity of saline matter in the first variety. It 
 consisted of common salt, muriate of potash, the sulphates 
 of potash, gypsum, magnesia, and iron, with phosphate of 
 soda, and other salts. The presence of this comparatively 
 large quantity of these different saline substances, original- 
 ly derived, no doubt, in great part from the sea, was proba- 
 bly one reason why it could be so long cropped without 
 manure. Its composition illustrates the truth of the state- 
 ment, that a considerable supply of all the species of inor- 
 ganic materials is necessary to render a soil eminently fer- 
 tile. Not only does this soil contain a coniparatively large 
 quantity of the soluble saline matters above enumerated, 
 but it contains also 10 per cent, of organic matter, and 
 some lime. The potash and soda, and the several acids, 
 are also present in sufficient abundance. 
 
 In the second instance, a fertile soil, but which could 
 not dispense with manure, there is little soluble saline mat- 
 ter ; and in the insoluble portion, only traces of potash, 
 soda, and the important acids. It contains, also, 5 per 
 cent, of organic matter, and 2 per cent, of hme, which 
 smaller proportions, together with the deficiency oj alkalies, 
 remove this soil from the most naturally fertile class, to that 
 class which is susceptible in hands of ordinary skill, of be- 
 ing brought to, and kept in a very productive condition. 
 
 Sir Humphrey Davy examined some productive soils, 
 which were very different in their composition. 
 
 We will state the analysis of a few of them. 
 
 Soil from Holkham, Norfolk, described as a " good 
 turnip soil,'^ contained 8 parts out of 9 of siliceous sand ; 
 that is, sand with flint earth, or silex : the remaining l-9th 
 part consisted, in every 300 grains, oi — 
 
 7* 
 
138 
 
 PRODUCTIVE FARMING. 
 
 Carbonate of lime, (chalk) 
 Pure silex, .... 
 
 Pure alumina, or the earth of clay, 
 Oxide (rust) of iron. 
 Vegetable, and other saline matter. 
 Moisture and loss, 
 
 63 grains. 
 
 15 grains. 
 
 11 grains. 
 
 3 grains. 
 
 5 grains. 
 
 3 grains. 
 
 100 
 
 Thus the whole amount of organic matter in this instance 
 is only 1 part in 200, or one-half per cent. ; a fact which, 
 in itself, would demonstrate the fallacy of supposing that 
 decomposed animal and vegetable matter in the soil form 
 the exclusive supply to growing plants. 
 
 In another instance, soil was taken from a field in Sus- 
 sex, remarkable for its growth of flourishing oak trees. It 
 consisted of 6 parts of sand, and 1 part of clay and finely- 
 divided matter. One hundred grains of it yielded, in che- 
 mical language — 
 
 Of silica, (or silex) 
 
 Of alumina, 
 
 Carbonate of lime. 
 
 Oxide of iron, 
 
 Vegetable matter in a state of decomposition, 
 
 Moisture and loss. 
 
 54 grains. 
 28 grains. 
 
 3 grains. 
 
 5 grains. 
 
 4 grains. 
 
 6 grains. 
 
 100 
 
 To wheat soils, the attention of the practical farmer will 
 be most strongly directed. An excellent wheat soil from 
 West Drayton, in Middlesex, yielded 3 parts in 5 of sili- 
 ceous sand ; and the remaining two parts consisted of car- 
 bonate of lime, silex, alumina, and a minute proportion of 
 decomposing animal and vegetable remains. 
 
 Of these soils, the last was by far the most, and the first, 
 the least coherent in texture. In all cases, the constituent 
 parts of the soil which give tenacity and stiffness, are the 
 finely-divided portions ; and they possess this quality in 
 proportion to the quantity of alumina (or earth of clay) 
 they contain. A small quantity of this finely-divided mat- 
 ter is sufliicient to fit a soil for the growth of turnips, or of 
 barley, as turnips will grow (though it is not to be ex- 
 
PRODUCTIVE FARMING. 139 
 
 pected they will thrive) on a soil containing 11 parts out of 
 12 of sand. Sand in much greater proportion, or rather 
 disproportion, produces sterility. So pure alumina, or pure 
 silex, pure chalk, or magnesia, are incapable of supporting 
 vegetation ; and no soil is fertile that contains 19 parts 
 out of 20 of any one of the materials that have been men- 
 tioned. 
 
 Sprengel gives also the analysis of an unproductive soil 
 from Luneburg. It contained, in 1000 parts — 
 
 Soluble saline matter, .... 1 part. 
 
 Fine earthy and organic matter, (clay) . . 599 parts. 
 
 Siliceous sand, ..... 400 parts. 
 
 1000 
 
 This unfruitful soil, compared with the analysis given of 
 the other two on a previous page, will be found to be the 
 lightest of the three, containing 40 per cent, of sand. But 
 this alone is not enough to account for its barrenness,- 
 many light soils containing a larger proportion of sand, 
 and yet sufficiently fertile. One thousand parts of its fine 
 earthy matter contain 40 of organic matter instead of 97, 
 — 778 of silica instead of 648, — 91 of alumina instead of 
 57, — 4 of lime instead of 59, — 1 of magnesia instead of 
 10, — 8 1 of oxide of iron instead of 6 1 ; while potash, soda, 
 ammonia, chlorine, sulphuric acid, phosphoric acid, car- 
 bonic acid, are entirely wanting ; such being the ingredi- 
 ents and quantities in 1000 parts of the finer portion of the 
 very fertile soil from East Friesland. The oxide of iron is 
 in excess in the Luneburg barren soil ; there requires, there- 
 fore, to be added, not only those substances of which it is 
 destitute, but such other matters as shall prevent the inju- 
 rious effects of the excessive proportion of iron. This 
 illustration may serve to aid the practical farmer in com- 
 prehending how far exact chemical analysis is fitted to 
 throw light upon the capabilities of soils, and to direct ag- 
 ricultural practice. The constitution of a soil, like the 
 constitution of a horse, or a human being, requires to be 
 known and understood, if we would prescribe otherwise 
 than at random, expensively, unprofitably, or injuriously, 
 
140 PRODUCTIVE FARMING. 
 
 either for the diseases of the one, or for the deficiencies of 
 the other. 
 
 The varying power of soils to absorb and retain water 
 from the air, is much connected with their fertility. Sir 
 Humphrey Davy has remarked upon this; and connecting 
 his statement with the fact, that rain-water always con- 
 tains ammonia, and, consequently, nitrogen, (as one of the 
 elements of ammonia,) w-e can easily undeistand why it 
 should be so. He observes, that " the soils which are most 
 efficient in supplying a plant with water by absorption and 
 retention from the atmosphere, are those in which there is 
 a due mixture of sand, finely divided cloy and chalk, with 
 some animal and vegetable matter; and yet so loose and 
 light, as to allow the action of the air beneath the surface." 
 Sand in excess destroys the requisite stiffness of the soil, 
 but gives little absorbent power. 
 
 The absorbe7it power of land is always greatest on the 
 most fertile soils, thus affording one ready test of produc- 
 tiveness. One thousand grains of soil, rendered perfectly 
 dry by exposure to heat equal to that of boiling water, 
 ought, by exposure to air, saturated with moisture, to gain 
 in weight, at least 18 grains, or one-fiftieth ; so that the 
 standard of fertility of soils for different plants must vary 
 with the climate, (as well as the varying constitution of 
 the soil itself,) and be particularly influenced by the quan- 
 tity of rain that falls upon it. The power of soils to absorb 
 moisture ought to be much greater in warm or dry coun- 
 tries, than in cold, marshy places; and the quantity of clay 
 they contain, greater. The inference is obvious : if defi- 
 cient, it ought to be added. Soils, also, on the slope of 
 a hill, ought to be more absorbent than in plains, or in the 
 bottom of valleys. Their productiveness is also much in- 
 fluenced by the nature of the sub-soil on which they rest; 
 for, when soils are immediately situated upon a bed of rock 
 or stone, they dry sooner by the sun's agency, than when 
 the sub-soil is clay or marl. A prime cause of the fer- 
 tility of the land in the moist climate of Ireland is, that 
 happily the surface-soil rests upon a rocky substratum. A 
 
PRODUCTIVE FARMING. 141 
 
 clay sub-soil will sometimes be of material advantage to a 
 sandy upper-soil, inasmuch as it will retain the necessary 
 moisture in such a manner as to be capable of supplying 
 that lost by the earth above in consequence of evaporation. 
 In the same way, a sandy or gravelly sub-soil often corrects 
 the imperfection of too great a degree of absorbent power 
 in the true soil. 
 
 In devoting the different parts of an estate to the neces- 
 sary crops, it is perfectly evident that no general principle 
 can be laid down, except when all the circumstances of the 
 nature, composition, and situation of the soil and sub-soil 
 are accurately known. 
 
 Whatever be the specific variety of the surface-soil, 
 it will, of necessity, take its character from the prevalent 
 substratum. In limestone countries, where the surface is a 
 species of marl, the soil is often found only a few inches 
 above the limestone, and its fertility is not impaired by the 
 nearness of the rock : though, in a less absoi bent soil, this 
 situation would occasion barrenness ; and tfie sandstone 
 and limestone hills in Derbyshire and North Wales may be 
 easily distinguished at a distance in summer by the different 
 tints of their vegetation. The grass on the sandstone hills 
 usually appears brown and parched, that on the limestone 
 hills flourishing and green. 
 
 Each locality will continue to present to the agricul- 
 turist facilities for the cultivation of such vegetables 
 as it is best fitted to raise, and for an indefinite period ; 
 that is, until the exhaustion of its saline materials, its 
 capability will continue. In clayey soils, it will continue 
 longest ; because, as previously explained, all clays con- 
 tain potash and soda. But even these in time are exhaust- 
 ed. Air, water, and the changing temperature of the 
 seasons, are at the same time preparing a remedy for the 
 coming deficiency. Fresh surfaces of broken, crumbling 
 rock are in a state of continual formation, exposing to the 
 elements the saline treasures they contain. A period will 
 arrive in the history of all soils, when, if their saline con- 
 stituents are not artificially replaced, it will be necessary, 
 
142 PRODUCTIVE FARMING. 
 
 either by deep ploughing, or other mechanical modes of 
 breaking up and exposing the rock from which that soil 
 has been formed, to obtain a fresh supply of soluble alka- 
 lies. When the surface of a granite rock has been long 
 subjected to the action of air and water, the lime and the 
 potash it contains are acted on by both ; the felspar, mica, 
 and quartz, of which that rock is compounded, are decom- 
 posed. The felspar, which is, as it were, the cement of the 
 stone, forms a fine day ; the mica, partially decomposed, 
 mixes with it ?iS sand; and the undecomposed quartz appears 
 as gravel, or coarse sand, of different degrees of fineness. 
 Then, as soon as the smallest layer of earth is formed in 
 this way, the seeds of mosses, and other imperfect vegeta- 
 bles constantly floating in the atmosphere, and which have 
 made that spot their resting-place, begin to vegetate : their 
 annual reproduction and death furnishes a certain quantity 
 of organizable matter, which mixes with the earthy mate- 
 rials of the rock. In this improved soil, more perfect 
 plants are capable of subsisting, the gradual process being, 
 in truth, an epitome of the world's original creation. Fos- 
 sil geology shows us that such was the process ; and that 
 not until a soil was formed by the decay of reeds and 
 mosses, was the earth's surface fitted to rear the stately 
 oak. With every fresh disintegration of the surface, suc- 
 cessive quantities of alkaline materials are presented to the 
 growing vegetable. 
 
CHAPTER XII. ! 
 
 ! 
 Of the Chemical Analysis of Soils, and how far this is practicable i 
 by the Farmer. 
 
 Enough has been already written to show what is es- : 
 sential to the production of heavy crops, and to prove that 
 a naturally good soil can be forced, or an inferior soil 
 amended, only by the addition of such substances as are 
 really requisite in each particular instance ; such adaptation, 
 of course, pre-supposing an exact acquaintance with the 
 nature of the land. 
 
 But the practical farmer will anticipate the inquiry, 
 How am I to arrive at this knowledge 1 I am no chemist: ! 
 I can form some general notion of the composition of the 
 soil which I cultivate; and, from experiments, (some of 
 which have been fortunate, others confessedly expensive 
 and unproductive,) I am enabled to say what seems to 
 agree best with it. Is it necessary to employ a scientific 
 chemist to analyze my wheat soils, or are the means of 
 discovery within my own power? \ 
 
 In reply to such very natural inquiries, — to a certain i 
 extent, the means of analysis are within the reach of every I 
 working farmer. Nevertheless it is perfectly true, that the 
 management and tilling of the soil is a branch of practical 
 chemistry ; and like the arts of dyeing, calico printing, or 
 the smelting of metals, it may advance to a certain degree \ 
 of perfection, — its present condition, (which has been sta- 
 tionary and imperfect for many centuries,) — without the aid 
 of science ; but it can only have its processes explained, and 
 be led on to shorter, more economical, more productive, and 
 perfect processes, by the aid of scientific principles. 
 
 From the analysis of Davy and Sprengel, already given, 
 
144 PRODUCTLVE FARMING. 
 
 of soils known to be enainently productive, (and two or three 
 such iUustrations are as good as a thousand,) it is not diffi- 
 cult to say of what materials a good wheat soil ought to 
 consist. It is impossible to compare any given soil with 
 these standards, unless we have a similar examination in- 
 stituted ; and if it can be obtained from the hands of an 
 able investigator, it is always very desirable, so much so as 
 amply to repay the trifling expense. Chemistry has ren- 
 dered many and great services to agriculture, and can render 
 more : the two sciences ought not to be considered as hav- 
 ing no relation to each other ; on the contrary, practical 
 farming is only conducted on rational principles when di- 
 rected by chemical science. Hitherto, it has fallen in with 
 the humour or bias of only a few scientific men to enter 
 upon such inquiries. Sir Humphrey Davy, the greatest 
 chemist of his age, devoted his elTorts not only laboriously, 
 but most usefully, to the prosecution of agricultural chem- 
 istry ; and the recent views and discoveries of Liebeg, will 
 do much to economize agricultural operations, as well as to 
 direct the farmer to the easiest and shortest modes of doub- 
 ling his crops. But generally, the appreciation of such ef- 
 forts, on the part of learned men, has been so small — the 
 reception of scientific results and suggestions by the farm- 
 ing tenantry, so ungracious, that little wonder can exist that 
 so many have quitted the field in disgust — that the majority 
 of able chemists should studiously avoid it. Hence it has 
 happened that in England, the analysis of soils has rarely 
 been undertaken, except as a matter of professional busi- 
 ness. Exact chemical analysis is a difficult art, one which 
 demands much knowledge and skill in practice. It calls 
 for both time and perseverance, if valuable, trustworthy, 
 and minutely correct results are to be obtained. But it is 
 only by aiming after such minutely correct results that chem- 
 istry is likely to throw light on the peculiar properties of 
 those soils, which,while they possess much general similarity 
 in appearance, are yet found, in practice, to possess very 
 different agricultural capabilities. 
 
 Sir Humphrey Davy has given, with his usual precision, 
 
PRODUCTIVE FARMING. 
 
 145 
 
 very copious directions for the analysis of soils. But we 
 have no hesitation in affirming, that few practical farmers 
 are likely to attempt the task. Not that the requisite in- 
 struments are either numerous or expensive, but that some 
 familiarity with chemical operations is necessary ; and that 
 little dependence could be placed upon results which, if in- 
 correct, would mislead perhaps more widely than the merest 
 p-uesses. Fortunately there are to be found men of ability 
 in sufficient numbers to supply the requisite information ; 
 and there is nothing more inconsistent in soliciting from a 
 practical chemist a statement as to the actual composition 
 of a given portion of soil, with a view to the supply of its 
 deficiencies, than there is in employing a veterinary surgeon 
 not only to give an opinion as to the nature of the ailment 
 of a horse, but to advise the appropriate remedy. 
 
 Undoubtedly, the utility and necessity of such interfer- 
 ence or assistance may sound strangely— grate harshly 
 upon the long-established usages of that class of English 
 farmers with whom, unfortunately, mere exertion is a vir- 
 tue, and skill or science a presumed apology for laziness. 
 It would appear however, that in some agricultural dis- 
 tricts, a spirit in most rational conformity with such com- 
 binations of science with mere brute labour, is beginning 
 to prevail. Early in the present year, a meeting of landed 
 o-entry and farmers took place in Edinburgh, tor the ex- 
 press purpose of forming an association /or the application 
 of chemistry to agriculture ; a tolerably expressive indi- 
 cation of the state of public feeling in Scotland, and one 
 that, we trust, will be followed up by the organization of 
 kindred institutions throughout the entire kingdom. The 
 srreat and leading object of the association is to have a 
 chemist of first-rate eminence, resident in Edinburgh, who, 
 during the winter months, shall devote himself to analyzing 
 such soils, manures, and other substances as may be sent 
 him by farmers, and giving them advice regarding their 
 value and usefulness. In summer he will visit different dis- 
 tricts of the country, at the request of members of the as- 
 sociation, and give a few lectures in the towns, or advice 
 
146 PRODUCTIVE FARMING. 
 
 to individuals, regarding the system of management best 
 suited to different soils. It is easy to see that all this will be 
 attended with very great practical benefits to the country. 
 
 We are aware, however, that there are persons who 
 have a distrust of the aid to be had from chemistry in the 
 delicate and refined processes of agriculture ; and to them 
 we would address a few words. 
 
 Now, the more recondite principles of vegetation are 
 subjects on which neither chemist nor farmer will require 
 to touch, Indeed, there will be no call made on the farm- 
 ers ^ or j)ersons wishing the analysis, for any chemical 
 knowledge. They are to submit limestones, bone-dust, 
 guano, and manures of all kinds, marls, decaying rocks, 
 and such like substances, to the chemist, and he is to pro- 
 nounce on their value, and to point out their utility in 
 reference to different soils, and for raising different crops. 
 He will say, for example, whether the guano has been 
 robbed of its ammonia, or the bone-dust of its gelatine, or 
 whether the limestone be coloured with bituminous matter 
 which will disappear with burning, or with iron which will 
 not ; and then he will be able to say w^hat price the article 
 ought to bear, and with what crops, on what soils, and at 
 what periods it ought to be used. On the part of the per- 
 son who sends the substance for analysis, it is plain that no 
 knowledge of chemistry is required ; and even the chemist 
 will not find his duty an arduous one. A few chemical 
 tests, and an accurate balance, will be nearly all that he 
 will require ; and he will have no occasion to approach 
 those nice and subtile operations of nature, over which 
 there certainly hangs a delicate and almost impenetrable 
 veil. 
 
 But the summer duties of the chemist will be even 
 more important than the analysis which are to occupy his 
 winter hours. During that season he will impart informa- 
 tion on many of the more recent discoveries and improve- 
 ments in practical agriculture; and already enough has been 
 done to admit of his giving much valuable and curious 
 information, whether in the form of lectures, or by commu- 
 
PRODUCTIVE FARMING. 147 
 
 nicating with individuals. For example, the good effects 
 of bone-dust, and of the phosphates generally, on peaty 
 soils — of saline compounds for crops of hay on loams in 
 trap districts — and of lime on granitic soils — may be men- 
 tioned, and they admit of explanation. They are noticed 
 here as a proof of the advancement already made in this 
 kind of knowledge. But much yet remains to be done ; 
 and besides giving information, it will be his duty no less 
 to suggest experiments. He will give instructions to 
 farmers to make trial of substances, the composition of 
 which is known and determinate, on different soils, and 
 \vilh a variety of crops, accurately noting the weight of 
 the produce, both in its dry and moist state. And who does 
 not see that such trials, made on a diversity of soils, (for in 
 this respect the experiments will have the advantage over 
 any which the chemist could make himself on an experi- 
 mental farm,) will furnish him with results from which he 
 may possibly draw some general principle. This, again, 
 may point the way to other trials and new discoveries j and 
 so on without limit. 
 
 Need we say what will be the benefits of all this train- 
 ing and experiment 1 In the first place, there will be a 
 gain to the country at large in the increased productive- 
 ness of the land ; and in this those will be the first to 
 share who first know of the new methods that will give 
 them crops at a lower cost than their neighbours. And, 
 in the second place, a spirit of intelligence and inquiry can- 
 not fail to be diffused among our farmers, of which it will 
 be difficult to estimate the value. Instead of blindly fol- 
 lowing in the old courses, they will have a pleasure in 
 devising new ones, and will gradually raise themselves in 
 the scale of being. And if it be true that even the mechan- 
 ical arts will fall off, as DeTocqueville has admirably shown, 
 if their principles are lost sight of, just as copies taken from 
 copies decline at last from the original, much more will the 
 fields of the farmer, changing in their composition with every 
 crop that is taken from them, reward none at last but the 
 intelligent and the skilful. 
 
CHAPTER XIII 
 
 Of Advertised "Fertilizers" for the Soil. 
 
 The publication of more scientific and enlarged views 
 respecting the nature of vegetable growth, has led to the 
 attempt to furnish mineral compositions to meet the supposed 
 deficiency of saline matters in the soil. Their inventors 
 secure the secret of each such composition by a patent -, in 
 other instances they are left unprotected : nevertheless, it 
 is a matter of no difficulty to say of what materials they 
 chiefly consist. Now, there are such things as patent medi- 
 cines, and, unquestionably, there is scarcely one of them 
 that may not be good for some ailment or other. The mis- 
 chief of such nostrums is, that they are recommended as 
 universal specifics ; they will cure every thing. As any 
 one may read of the last new fashionable pills, that they 
 have stood the test of thousands of trials, ancl proved effica- 
 cious in the removal of the direst and most diversified evils 
 that can infest humanity ; so of these agricultural specifics, 
 it is said that " their efficacy has been submitted to innu- 
 merable tests since the ingredients were discovered ; by 
 which trials their utility has been amply demonstrated in 
 all instances." Now, this is saying too much. Macassar 
 oil may cause a luxuriant growth of hair ; but rubbed upon 
 a deal box, it will not convert it into a hair-trunk before 
 the morning : and so a remedy, said to be universally \\sek\\, 
 mostly proves (whether land or living creatures be the sub- 
 ject of experiment) of little use in any instance. In some 
 cases that have fallen under our own notice, the guano, 
 which these mineral manures were intended to supersede, 
 has proved a far more strongly-fertilizing substance. And 
 if there had been no deficiency of the materials of which 
 guano is exclusively composed, — if purely saline and earthy, 
 rather than animal matter, had been wanting, the balance 
 
PRODUCTIVE FARMING. 149 
 
 of recommendation would undoubtedly have turned the 
 other way. All this shows that it is folly to add to a soil 
 any other matters than precisely those which are exhausted 
 or deficient; and that this can only rationally be attempted 
 after a close examination of the materials of which that 
 soil is composed. 
 
 Let us suppose this is done, and that an artificial saline 
 or mineral compost is judiciously and accurately put to- 
 gether, either to meet the deficiency, or added to a tolerably 
 good soil to increase its fertility. The advantages of its 
 use are not overstated in a recent pamphlet. 
 
 1st, It is cheap, compared with its value : a twenty 
 shilling cask will supply an acre. 
 
 2d, It is light and easily carried, when compared with 
 carting manure. 
 
 3(i, It is suitable for small holders who cannot aflford 
 soiling, or keeping of cattle for making dung-heaps. 
 
 Uh, It enables a tenant-at-will to take a good crop 
 out of done-out land, if his landlord refuse to renew. 
 
 bth, It furnishes to barren land such food for plants as 
 had been deficient ; such defects of one or more substances 
 being, in general, the cause of sterility. 
 
 Qth, It enables the cultivator to extract ten times as 
 much vegetable aliment for his plants from the soil, and 
 from other manure, as they could otherwise, in most cases, 
 yield. 
 
 This is the language of one who has devoted much 
 time, talent, and energy to the task of improving the soil ; 
 and he believes there are no soils which may not be per- 
 manently fertilized by the mineral compost which forms 
 HIS invention. Thus he speaks of its powers. But bear- 
 ing in mind the remarks we have already made, every 
 practical farmer must advance upon his own responsibility 
 in making trial of its capabilities ; the object of this work 
 being, not the introduction of advertised artificial manures 
 into the notice of the agricultural world, but rather the 
 dissemination of those sound and rational views of the 
 
160 
 
 PRODUCTIVE FARMING. 
 
 necessary relations between practical farming and practi- 
 cal SCIENCE, without which Agriculture must still lacr 
 'behind the age, and, though the first and most importanl 
 oi all arts, remain for ever stationary. 
 
 THE END. 
 
'i^l i%^\ 
 
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