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tricts of that State, embracing in the aggregate nearly a million of volumes, so that a traveller cannot be stopped anywhere within its wide bounds, without being within two or three miles of some good reading. The appropriation, just made by Massachusetts for the same purpose, amounts to between thirty and forty thousand dollars, which is doubled by means of the condition, that each district shall contribute an equal sum to that furnished from the public fund.
Art. X. -- Organic Chemistry in its Applications to Ag-'
riculture and Physiology, by Justus LIEBIG, M. D.,
We welcome the appearance of a second American edition of this work, as indicative of the general interest attached to scientific views of agriculture in this country, as well as of the determination of the public to second the efforts of scientific men in making their knowledge and studies useful to mankind ; and the decidedly favorable reception, by all classes, in various parts of the world, of such a treatise, is a proof how extremely desirable had become the developement of some sound general principles of action in agriculture, and how difficult or impossible it had hitherto been to deduce such useful general principles from the mere customs which have obtained, or from the experiments of the practical farmer, unassisted by the severe discriminations, or the matured experience and judgment, of science.
The great value of the coöperation of science consists in the concentration of all the powers of the mind on one specific object. The chemist never undertakes an experiment without a certain definite end always kept in view, and he takes every measure his ingenuity and experience can suggest to obtain clear and decisive results ; watching at the same time with the utmost care, any appearances which may lead to further information unconnected with this end.
The farmer, on the other hand, tries various experiments without sufficient examination of the primary conditions, without keeping careful watch on their progress, and with comparatively uncertain judgments on the results.
Thus if the chemist wished to produce muscle on an animal, he would first examine the constituent parts, and if nitrogen were ascertained as a chief ingredient, he would endeavour to procure such agreeable food for the animal as would yield the largest portion of nitrogen with its other materials. Again, if it be required to find this vegetable, containing a large quantity of nitrogen, he would analyze various kinds of vegetables fit for the nutriinent of the animal, and select the one proper for his trial ; and in treating the soil for the luxuriant production of this vegetable, he would take care that it should contain a superabundance of nitrogen from which the growing plant would supply itself. His experiment might succeed or might fail; but it is clear that this method of inductive reasoning, this preparation of conditions, would afford a better chance of success than the blind operations of the farmer.
Hence, such works as the present are highly valuable not only as means of disseminating knowledge, but also as means of inducing those habits and trains of thinking among agriculturists, which may enable them to act and judge for themselves on objects of advantage to them, and readily to discern between true knowledge and empiricism.
It is evident, however, that we are but just entering on a field of inquiry of immense extent, and of infinite value.
The scheme of analysis of various vegetables has hitherto been shaped by the chemist chiefly for philosophical purposes and research ; that which is formed for agricultural purposes must evidently vary from this considerably
Simple incineration will give the fixed alkalies and the earths, incineration in contact with deutoxide of copper will give the carbon, and the ultimate principles into which vegetables can be resolved ; treatment with alcohol and ether will give the gums, resins, and the other proximate principles into which they may be separated, many of which, as quinine, morphia, &c., are useful to mankind. But the vegetable juices existing in the living plant are so exceedingly delicate, so very susceptible of transformation, by the addition or abstraction of minute portions of oxygen, &c., and by the action of heat and light,
VOL. LIV, — No. 115. 61
that only very general and indefinite ideas on the subject of their nutriment can be obtained from these sources.
The future developement of the science of vegetable analysis will no doubt exhibit the means of examining the fresh juices of plants, expressed from their various parts, both previously and subsequently to their alteration by the functions of the leaves or flowers'; for it is certain, that the nearer we approximate the examination of these juices to their absorption from the earth by the roots, the more clear ideas we shall obtain of the requisites and conditions for their formation and production.
The following extract from the concluding lecture of M. Dumas, in his Course at the School of Medicine in Paris, which has excited general admiration, will show the attention now paid to Liebig's comparatively new views of the relations of the vegetable kingdom.
“Have we not proved in fact, by a multitude of results, that animals constitute, in a chemical point of view, a real apparatus for combustion, by means of which burnt carbon incessantly returns to the atmosphere under the form of carbonic acid ; in which hydrogen, burnt without ceasing, on its part continually engenders water ; whence, in fine, free azote is incessantly exhaled by respiration, and azote in the state of oxide of ammonium by the urine ?
"Thus from the animal kingdom, considered collectively, constantly escape carbonic acid, water, in the state of vapor, azote, oxide of ammonium ; simple substances, and few in number, the formation of which is strictly connected with the history of the air itself. Have we not, on the other hand, proved that plants, in their normal life, decompose carbonic acid for the purpose of fixing its carbon, and of disengaging its oxygen ; that they decompose water to combine with its hydrogen, and to disengage also its oxygen ; that, in fine, they sometimes borrow azote directly from the air, and sometimes indirectly from the oxide of ammonium or from nitric acid, thus working, in every case, in a manner the inverse of that which is peculiar to animals?
* If the animal kingdom constitutes an immense apparatus for combustion, the vegetable kingdom, in its turn, constitutes an immense apparatus for reduction, in which reduced carbonic acid yields its carbon, reduced water its hydrogen, and in which also reduced oxide of ammonium and nitric acid yield their ammonium or their azote.
“ If animals, then, continually produce carbonic acid, water, azote, oxide of ammonium, plants incessantly consume oxide of ammonium, azote, water, carbonic acid. What one class of beings gives to the air, the other takes back from it. ..... Thus plants and animals come from the air, and thus to it they return; they are real dependents on the atmosphere.
“Plants, then, incessantly take from the air what is given to it by animals, that is to say, carbon, hydrogen, and azote, or rather carbonic acid, water, and ammonia.
"It now remains to be stated how, in their turn, animals acquire those elements which they restore to the atmosphere ; and we cannot see without admiration the sublime simplicity of all these laws of nature, that animals always borrow these elements from plants themselves.
" We have indeed ascertained, from the most satisfactory results, that animals do not create true organic matters, but that they destroy them ; that plants, on the contrary, habitually create these matters, and that they destroy but few of them, and this, in order to effectuate particular and determinate conditions. Thus it is in the vegetable kingdom, that the great laboratory of organic life is placed; there it is, that the vegetable and animal matters are formed, and there they are produced at the expense of the air. From vegetables these matters pass, ready formed, into the herbivorous animals, which destroy a portion of them, and accumulate the remainder in their tissues ; from herbivorous animals they pass, ready formed, into the carnivorous animals, who destroy or retain some of them according to their wants ; lastly, during the life of these animals, or after their death, these organic matters, as they are destroyed, return to the atmosphere whence they proceeded.
“ Thus closes this mysterious circle of organic life at the surface of the globe. The air contains or engenders oxidized products, as carbonic acid, water, nitric acid, oxide of ammonium. Plants, constituting a true reducing apparatus, possess themselves of their radicals, carbon, hydrogen, azote, ammonium. With these radicals, they form all the organic or organizable matters which they yield to animals. These in their turn, forming a true apparatus for combustion, reproduce carbonic acid, water, oxide of ammonium, and nitric acid, which return to the air to produce anew, and through endless ages, the same phenomena."
The discovery of Liebig, of the supply of ammonia or nitrogen to plants from rain-water and snow, will probably be carried to a much further extent, and involve points of great value to agriculture. Already has it been found in Germany, that several seeds of Alpine plants, particularly of some Gentians,
whose germination has hitherto been attended with much difficulty, will grow readily if sown in contact with snow. Now ammonia does not easily evaporate from water at the temperature of snow; hence these seeds, shed on the surface of the earth, naturally remain a long time in contact with a substance (snow) containing a small quantity of ammonia ; and, indeed, it is not impossible that some of the integuments of seeds, of which, except as a covering, the use is not at present very apparent, may be constructed with a view of serving for absorption, or for some other action in relation to substances requisite for their germination. Many unsuccessful attempts have been made here to raise plants of Gentiana crinita, of Gerardia, and of Eucroma, from seed gathered in the autumn and sown in the spring ; the probable cause of the failure, according to the above statement, should be the want of the condition, under which it is sown naturally, that is, contact with snow. The seed of Gerardia has a beautiful and peculiar cellular integument.
It is, in fact, impossible at present to divine what may be the results of the attention to these subjects, to which this work has given rise ; that they will be generally beneficial admits of no doubt. It is pleasant to reflect on the general feeling of common brotherhood and citizenship, which such beneficial discoveries engender amongst individuals of various nations. How different are the emotions they produce from those which arise from the discoveries, miscalled improvements, in the savage art of war ; and what fond anticipations is the philanthropist led to indulge, of the early universal conversion of the sword and the gun into the plough-share and the reaping-hook, and of saltpetre into a powerful manure.
Like all other new propositions offered for assent to the mind, those contained in Liebig's work will have to pass through the severe ordeal of the judgment, both of the experienced and of the inexperienced, both of the chemist and of the practical agriculturist, and much criticism has already been applied, and much opposition exhibited, to several of his doctrines. Still, no chemist of fixed reputation in Europe has yet ventured to assail the chemical principles there laid down ; and, if true, they will work their own way. With respect to the agriculturist, it must be remembered, that this book was written by a chemist for chemists, not by a farmer for farmers ; these last have yet something to learn,