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man to consider, which have either never been sufficiently prominently presented to his view, or which from their being less striking, or perhaps less enticing, have been allowed to fall into the back ground, and have hence led to a certain amount of misapprehension in regard to the exact position of science and its relations to practice. Such misapprehension it is highly desirable to dispel. The farmer and the chemist should come to a distinct understanding with regard to the mutual bearings of scientific and practical agriculture—the manner in which they may be made to assist one another -and, what is of all others the most important point, how they can be made to co-operate, so as to establish on a firm basis the general principles of agricultural science, which must necessarily be the first step towards the development of a scientific practice. Under these circumstances, I have thought that I might advantageously refer very shortly to some of these matters, nd point out what we are in future to expect from the application of chemistry to agriculture, the more especially as it is not very difficult to perceive that the interest which attached to it has somewhat abated with the general public, though I believe it to be undiminished with our most active and intelligent practical men.
This very diminution in the interest attaching to chemical agriculture, I believe to be mainly founded on one of the most serious misapprehensions-serious alike to agriculture and to chemistrywith which we have now to contend; and that is the erroneous and altogether extravagant expectations which some persons entertain, regarding the extent and rapidity of the influence which chemistry is likely to exert upon agriculture. To hear them talk of it, one might almost imagine that chemistry, as by the wand of a magician, is at once to spread fertility over our barren moors and raise abundant crops where nothing ever grew before; and that the chemist can by a few simple experiments, determine with absolute precision, the circumstances under which the farmer must go to work so as to produce an abundant crop. It needs not to be mentioned that such views are the exception, not the rule; but between this extreme case and those likely to be fulfilled, there are many expectations which, with less apparent extravagance, are equally beyond the powers of chemistry in its present imperfect state, and involve questions which, if they ever can be answered, must await the advance of pure science to a point much beyond that to which it has yet attained. Nor is it, perhaps, matter of much surprise that such expectations should have been entertained, as it must be admitted that the general public is not in a position to estimate correctly the extent of the benefits which it is likely to derive from the application of science to any art; and unfortunately in the present instance, it has been misled by the far too laudatory terms in which the application of chemistry to agriculture were talked of some years ago. Hopes were then excited, which to those intimately acquainted with chemistry, it was very evident could not be sustained, but which the enthusiastic embraced at once; only, however, when they were disappointed, to abandon as worthless, the whole science itself, along with the unobtrusive modicum
of real progress, which was altogether lost sight of amidst the ruins of their lofty expectations. Even those who take a more cautious and sober view of the progress of agricultural chemistry, are apt to be led into expectations greater than facts justify, by the extraordinary progress which the application of chemistry has effected in some other arts; such for instance, as the art of bleaching and the manufacture of soda, which chemistry, by one great stride, raised from the state of primitive rudeness in which they had existed almost from time immemorial, to one at least of comparative perfection. Such facts may lead us at first sight, to expect that the application of chemistry to agriculture should be followed by equally rapid results; but a little further consideration seems to point out a very material difference between such arts and the cultivation of the soil. In such a case as the manufacture of soda, for instance, and indeed in all those in which the application of science has produced the most marked results, the chemist has presented to him for solution a definite and circumscribed problem, involving the mutual relations of some three or four different substances; and he is able to trace the changes which the coal, common salt and lime employed, undergo, from the commencement of the process through each successive step, until the soda is obtained in the perfect state; but in the art of agriculture each question frequently involves, not one, but many problems, connected with the highest and most abstruse doctrines of the science, in which not merely chemical forces, but the far more recondite phenomena of life come into play, and in which the investigations of the chemist are carried on, and his conclusions tested under the influences of weather, climate and many other perturbing causes.
The extreme complexity of the problems with which agricultural chemistry has to deal may be conceived from the fact, that most plants contain from twelve to fifteen different substances, all essential to their existence, the relations of which must be investigated before definite views can be obtained regarding the changes which go on in the organism of the plant. These relations, moreover, are far more complicated than even the number of the elements alone would lead us to suppose; the single element of sulphur, for instance, which does not constitute more than two or three parts in the thousand of most plants, exists there in not less than three different forms of combination, in each of which it is as essential to the plant as those which form the great proportion of its bulk. Now, it must be sufficiently manifest, that questions involving elements of such complexity are not to be solved as rapidly or easily as the far simpler problems of mineral chemistry, and that not merely on account of their superior complexity alone, but because, in the one case, theoretical chemistry sets us far on our way towards the solution, while in the other there is still a great gap to be filled up, a whole mine of scientific facts to be worked out, before we are in the condition to approach sufficiently near the comprehension of these more complicated phenomena. In fact, the latter are not questions of pure chemistry, but, are intimately interwoven with vegetable physiology-Bo much so, indeed, that in many instances
it is scarcely possible to decide to which of these two sciences they ought strictly to belong. And it is just herein that their great difficulty consists, for there is nothing more certain than that those questions which lie, so to speak, on the confines of two sciences, require for their successful investigation a high degree of development of both the sciences on which they depend. Now, chemistry is still far from having attained all that developement of which it is capable, as the time during which it has been cultivated has not been sufficiently long to admit of much progress, except in special departments. Few of those who are not themselves chemists, are aware that the facts and doctrines of modern chemistry have been determined during the last sixty or seventy years; and that, with few exceptions, all the laborious investigations of the older chemists, and, without exception, all their general doctrines, were then swept away, to be replaced by the science as it now exists; while organic chemistry, with which agriculture is more intimately connected, has been successfully prosecuted for not more than half that period. To expect any rapid advances, in the practical applications of agriculture, of chemistry in its present state, is manifestly unreasonable. The progress must necessarily be slow, in some instances almost imperceptible; and much must be done which at first sight the practical agriculturist may be inclined to consider altogether foreign to his object. Extended researches will frequently be requisite which do not directly lead to practical results—that is to say, which are not immediately convertible into an equivalent of current coin, but which are the foundation of such results, and form the starting point of perhaps a very different series of experiments, having an immediate bearing upon practice. It is of great importance that this should be distinctly understood and borne in mind; for it is by no means uncommon to suppose that nothing more is necessary than at once to convert scientific facts to practical purposes ; while, so far from this being the case, the agricultural chemist has a twofold duty to perform-he must both determine the scientific facts of agriculture, and eliminate from them the practical conclusions to which they lead. It may, perhaps, be said that the establishment of these facts falls within the province of the pure chemist, and that their practical application only ought to be the province of the agricultural chemist. But if this principle were to be acted upon, the progress of chemical agriculture would be slow indeed; for the investigations of the pure chemist lead him now, and are likely for a long period to lead him, in directions very remote from those most likely to afford the
materials which the agricultural chemist requires to work upon. The latter would, therefore, require to sit idly waiting till the former supplied him with facts, which his own exertions would have enabled him to ascertain. Nay, the agricultural chemist may even do a better service to agriculture, by pursuing the investigation of those apparently theoretical subjects, than by directing himself to those which seem to have the most immediate practical bearings.
There is another point on which there has been a good deal of misunderstanding between the chemist and the agriculturist, which
is intimately connected with the erroneous estimate of the extent and perfection of chemistry. It is not uncommonly supposed that the chemist is in the condition at once to solve, by the investigations of the laboratory, all such questions in practical agriculture as may happen to be submitted to him—that he can determine, when nothing else can, why certain methods of cultivation are successful, others unsuccessful. It is just possible that he may in some instances be able to do this, but far more frequently his researches enable him not to state positively what is or what is not the case, but rather to draw a probable conclusion-to form, in fact, a hypothesis, which is not in itself a truth, but which must be further tested by experiment in the field, whereby it may be either confirmed or entirely refuted. Now, very unfortunately, this hypothesis is often taken for a positive statement; and when it turns out to be erroneous, it is immediately held up as an instance of the fallacy of science by those who, not being themselves acquainted with the method of investigation by experiment, are unaware that all scientific facts are developed in such a manner. No one ever thinks of going fortuitously to work, when he proposes to determine a scientific fact. He first weighs all facts of a similar character, or having a bearing on the subject which he desires to elucidate, and then founds upon these a hypothesis, the truth or fallacy of which is to be tested by experiment.
Now, without any explanation, it has frequently happened that such hypotheses have been handed over to the practical man, whose field experiments having refuted them, he has forthwith abandoned the science which seemed to him to give erroneous results, not knowing that these results were only in progress of being arrived at by those very experiments which he was engaged in performing. The very same process has been employed in the applications of science to every other art; but the difference between them and agriculture is, that with the former, the hypothesis is formed and the experiments executed by the same person ; in agriculture the hypothesis must in many instances be handed over for experimental elucidation to the practical man. The many failures which are made in other arts remain unknown to all but those by whom they have been made, while in agriculture they become known to all and Bundry, and by them it is not understood that though these results are negative, they still serve to bring us all the nearer to the truth.
And this leads me to observe, that the true manner in which chemical agricnlture is to be advanced, is not merely by the exertions of the chemist or the labors of the laboratory alone. It must be by the simultaneous efforts of science and practice, each endeavoring to develop with care, steadiness and accuracy, the facts which fall within its province. Nor must each pursue its own course irrespective of the other. They must go hand in hand, and taking advantage of each other's experience, and avoiding all sorts of antagonism, they must endeavor to co-operate for the elucidation of truth. The chemist and the practical man are, in fact, in the position to give each other most important assistance. The one may point out the conclusions to which his science, so far as it bas
gone, enables him to come; while the other may test these conclusions by experiment, or may be able, from his experience, at once to refute or confirm them. But it will not do to imagine that there is here either a triumph or a defeat. Such a spirit cannot be any thing but injurious. It is rather to be looked upon as a fortunate state of matters, which admitting of the examination of our conclusions from two different points of view, directs us with the greater certainty in the path of truth."
It is undeniable that chemistry is as needful to the successful investigation of the principles which underlie agriculture, as an alphabet is needful to the study of language; and this, because it is only by its aid that we can understand the elementary constitution of matter and its affinities; and it is just as true, that alone, it is insufficient to teach a great deal which we need to know in agriculture, and this, because, (not to mention other deficiencies) chemistry proper teaches nothing at all in regard to living, organized matter. What is called organic chemistry, full of interest and importance as it most certainly is, is merely the chemistry of substances once organized and living, but alive no longer--the mere remains of organization. Chemistry cannot so much as put her finger upon living tissues, for they die ere it reaches them. No examination whatever of these by chemistry is possible, from the very nature of the case. A skillful chemist might be able to determine the proxi. mate constituents and the ultimate elements of which seeds are composed, but all the chemistry in the world could not enable him to determine of two seeds that one would produce an apple and the other a cabbage, nor to pronounce upon the conditions necessary to their successful development and growth.
It is the province of PaysIOLOGY to teach the laws in accordance with which are determined and regulated the production and development, the maintenance and decay of organic bodies; under which bead are included all the members of two of the great divisions in nature, viz: the vegetable kingdom and the animal kingdom. If we understand and obey these laws, we may secure abundance, symmetry, health and profit. If we disobey them, either through ignorance, carelessness or design, our wages are disease, decay, deformity and poverty.
The science of Botany is of use to the farmer, inasmuch as it enables him to recognize or identify plants, both those worthy of cultivation and the weeds which are troublesome or pernicious. Even