Book ,~-U PRODUCTIVE FARMING: OR = A FAMILIAR DIGEST OF THE RECENT DISCOVERIES OF LIEBIG, JOHNSTON, DAVY, AND OTHER CELEBRATED WRITERS ON y VEGETABLE CHEMISTRY ; SHOWING HOW THE RESULTS OF TILLAGE MIGHT BE GREATLY AUGMENTED. NEW yak: D. APPLETON & CO™™00 BROADWAY. PHILADELPHIA: GEO.S, APPLETON, 148 CHESNUT STREET. 1843. LK JOHN F. TROW, PRINTER, BalAn has treet, By Transfer Dept, of Agriculture OCT 17 1940 PRODUCTIVE FARMING. i ~—- aves ay = ay ro ’ ae i, stn. eg CONTENTS. CHAPTER I. Introductory Observations, - = = : 2 2 2 9 CHAPTER II. Some Account of the Simple or Elementary Bodies found (combined or uncombined) in Animals, Plants, and Soils, - 23 CHAPTER III. 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 gpeioned by the same agencies, - - - - - - - - - 33 CHAPTER IV. Of the Elementary Composition of Water ; of the Composi- tion of the Atmosphere ; and of the artificial mye 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 Sauces of the Element- ary Constituents of Plants, - - - - - = 60 CHAPTER VI. Of the Sources of the Saline, Earthy, and anne Ueereae Constituents of Vegetables, - « SE 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 8 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, - - 7. oe CHAPTER IX. Of the comparative Value of Vegetable Manure, as contrasted with Animal Excrements, - - - - - - = 196 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 Opera- tion as a Manure.—Of Alkalies and Common Salt, as to their Action upon the Land, : - - : - - 119 CHAPTER XI. Of the Composition of Productive Soils, and of the Agency of the Elements in their Natural Formation from the se upon which they rest, - - - S - - 129 CHAPTER XII. Of the Chemical Analysis of panty and how far this is pratt cable by the Farmer, - 143 CHAPTER XIII. Of Advertised “ Fertilizers’ for the Soil, - - - 148 PREFACE. Tuts 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 6 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. A~v~ROP Keee® ne [ies OF THE (yew vOR™ ‘egy UB MODERN AGRICULTURE. CHAPTER IT. Introductory Observations. AcricuLTuraL Science has for its objects all those changes in the arrangements of maiter 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 > a aS 10 PRODUCTIVE FARMING. good reason to believe, that he would be a more successful agriculturist 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 afford 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? 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 offered 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- telligence 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.” Half a 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 ylans; 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 aman 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 English 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 Jand; 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 which 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, may be 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 heat 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 1s 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, is 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 wuy they combine, or what 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 bysome 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 D ? 18 PRODUCTIVE FARMING. in their separate state may be, is not our immediate pur- pose. Carbon. Hydrogen. Oxygen. Nitrogen. Ash. 25 Cat RIN 5: 50 387 15 90 Potatoes, ’.’.” 441 58 439 2 50 Wheat straw, 485 52 389 4 70 ete eT 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 weight 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 form either the one or the other. The elements, therefore, into which all vegetable compounds are ultimately resolvable, are not merely mized 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 prozt- 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 af- 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 different 20 PRODUCTIVE FARMING. influence of the different solarrays on vegetation is but partially understood. There are rays transmitted from the 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 lective 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. pw | 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 aftrac- tion. In this aspect, there are five 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 altraction of cohe- sion: thus, particles of oil will rise through water, and having reached the range 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 4 32 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 sulphuric 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 affinity, 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 which are identical with the pro- cesses of growth in the vegetable world, and indeed in all PRODUCTIVE FARMING. pe living organized bodies,—and there are sufficient motives connected both with pleasure and profit to enBourage inge- nious men to pursue this new path of investigation. CUArTER fT, Some Account of the Simple or Elementary Bodies found (combined or uncombined) in Animals, Plants, and Soils. Ir 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 diffused 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. Oxyyen 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. Ifa 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. 2+ 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 will 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 which 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, will 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 anywhere in nature in any sensible separate quantity. They ‘are abundant enough in combination with othér matters. 3. Nitrogen, sometimes called Azote, is another ele- mentary substance, entering most largely into the constitu- PRODUCTIVE FARMING. 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 in it for want of oxygen. It combines in five different proportions with oxygen, forming, in one instance, nitric acid or aquafortis; and mized, 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 water, 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. Itis 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 range) 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 light 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 all 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 lime 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 waxy 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 phosphate of 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 98 PRODUCTIVE FARMING. unites with the oxygen 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 wineor in oil, but is insoluble in water, under which fluid it is always preserved. Jodine.—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. lodine is a dark-coloured solid, having somewhat the appearance of 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, wnifes, not mixes, with the lime, and in passing from the fluid to the solid state, gives out the Jatent heat necessary to maintain fluidity. This heat becoming suddenly sensible, is sufficient 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 lime 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 prover 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 between 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 water 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 base of common 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 with 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 sober metal which, in union with oxygen, forms silica, or siliceous earth, existing native in great abundance, and forming the chief ingredient in 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. Aluminium.—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.—tThe metallic base of the earth magnesia, the calcined magnesia of the shops. In combination with muriatic acid, it existslargely 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, sometimes 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, manganesum, iron, silicum, calcium, aluminum, and magnesium, enter into their composition, or are found in the agents to which they are exposed ; and these twelve, out of nearly sixty wndecompounded 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. Piants and Animats are both alike endowed with Lirr ; the Ele- mentary Materials and many of the Proximate Principles of Ani- mal and Vegetable matter are precisely identical—they have simi- lar OrGans essential to their growth and reproduction, and are nourished or destroyed by the same agencies. Ir 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. VVherever 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 of 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 asheep. But this description is not true of a piece of limestone, or a lump of clay, and, therefore, it is said to be znorganized. 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 crowths, are of this character. In what part ofa 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 ev ery 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 cul, 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. Carsonic acip, 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, we 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 as actually the case. The process of di- gestion in an animal is precisely identical with the process of appropriation or nourishment ina 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 wmmediate 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. Mucus, a secretion hedrn 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 largely 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 with 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 Jong 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. Animal fibrin isa 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 iscarbon. Fibrin is white, inodorous, and insipid ; when 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} of car- bon, hydrogen 7, oxygen 19, and 19 of nitrogen; 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 with water: as long as any milky juice exudes, the pre- sure 1s 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 434, oxygen 50, hydrogen 6}; or, in other words, carbon 434, 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 Japonica, 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 compo- sition is carbon, hydrogen, oxygen, and a little nitrogen. Tannin, or the tanning 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. Al carbon, 13.3-10ths of oxygen, and 10.7-10ths of hy- drogen. Waz 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 81.7-10ths, oxygen 5+, hydrogen 12.6-10ths, in 100 parts. Fized 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 :— OuiveE OIL. | SPERMACETI OIL. Carbon,:. §.) .-.77.2-10ths Carbon, Sc). CORY es SP Oxygen, . . . 9.4-10ths ORyeens dcheoredn ahd sree Hydrogen, . . 13.4-10ths Hydrogen, RD SEA RE fc | - — 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, difter 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 FARMING. 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 animalcule 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 bitter 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, Ist, 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 ; 3d, Lime, the metallic base of which = — PRODUCTIVE FARMING. 43 is calcium; and, 4thly, 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 veyeta- bles; sparingly in animal matter, very largely in sea-weed 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 offsets, the similarity, instead of being hereby 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 isa 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, Eacs, 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. A5 these have been for some time filled with stagnant water, 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, in 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, afoal, 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 peculiarity 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 eccurs in the straw- berry 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 itin 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 de- 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 1s 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 PRODUCTIVE 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.