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Many more such laws of nature have since been ascertained in chemistry, and thereby we have been enabled to answer with certainty how and why certain phænomena present themselves; since we have secured a foundation for these answers upon laws which, unlike human laws, cannot be arbitrarily evaded or changed. Their discovery has placed us in a condition to propound and to discuss, with a distinct perception of the present and prevision of the future, scientific chemical theories, that is to say, explanations of chemical processes Based upon laws of nature, by which alone we can attain to a clear apprehension of those chemical processes. All our knowledge is fragmentary! This confession, indeed, no chemist will refuse to subscribe, but, nevertheless, no undue presumption can be imputed to him, if he thinks that this fragmentary knowledge is yet sufficient to justify his proclaiming Chemistry one of the most interesting, practical, and profitable sciences, a science which every one should cultivate.

After this sketch of the nature of chemistry, a few examples, derived from manufacturing chemistry, may indicate the directions in which a beneficial application of this science to agriculture may be anticipated. Manufacturing industry possesses the greatest similiarity to agricultural, in so far that they are both dependent on the action of natural forces, and, indeed, of the same powers of nature. If the first has become great and powerful from the fact that, led on by science, it has not only arrived at a more intimate acquaintance with these natural powers, but, after having obtained mastery over them, has made them its servants: the expectation appears quite justifiable, that a more exact knowledge of these forces must be of advantage to practical agriculture.

It had long been known that wine or diluted brandy will turn into vinegar, if allowed to stand for a few months at the ordinary temperature, or for a few weeks in warm chambers, with free access of air. Chemical research demonstrated the constituent elements of the alcohol and of the vinegar formed therefrom, and showed that it must be possible to convert the former far more rapidly into the latter, by bringing the liquid into contact with very great quantities of air. This intimation was sufficient for the

manufacturer, and no long time elapsed before he ascertained the specific conditions under which this rapid conversion might be actually effected. The chemical process, which formerly lasted for weeks, nay, months, is now completed in as many hours, by the improved methods of acetification, and this, moreover, with far greater perfection and certainty.May it not, then, be considered probable, that the practical agriculturist would attain, if not more rapid, yet more complete and sure results, if accurately acquainted with the ingredients of the soil, together with those of the plants he wishes to cultivate upon it, and, that by this means, the possibility might perhaps even be revealed, of growing one and the same kind of crop constantly upon the same field?

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In the mineral kingdom there is a rather rare stone, of so beautiful a blue colour, that the painter weighed its worth in gold, using it as a pigment when ground to powder. A German chemist analysed it, and actually succeeded perfectly in reproducing it, with all its peculiar properties, from the constituent elements he found it to contain. splendid artificial ultramarine now met with in commerce, has thereby become so cheap, that it is bought at scarcely the hundredth part of the original price.-Does not this fact appear to warrant the conclusion, that we shall be able to prepare manures by artificial means, and cheaply, when continued investigations shall have established beyond all doubt the ingredients of the manures necessary to the nourishment of each individual plant ? Since the English have succeeded in discovering, in Spain, miles of a rock of phosphorite, a stone which consists of the same component parts as boneearth, the possibility seems not to admit of doubt, that more exact chemical investigation may discover in our own country, perhaps in our own immediate neighbourhood, various kinds of stone and earth or other substances, possessing a manuring property or capable of acquiring it by admixture with other elements.

What long prescriptions and what large bottles and boxes of medicine were formerly ordered by the physician, compared with the practice of the present day; how short and simple, in like manner, have the formulas and recipes become, by which the printer prepares his ley, the dyer his colour, the joiner his varnish! What is the reason of this

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change? Because a better insight into chemistry has demonstrated the exact value and mode of action of each ingredient of these recipes, and made it possible to separate the useless from the effective elements; whereas so long as the principle, that if one answered no good purpose, another might, remained in vogue, hesitation was necessarily felt as to the expediency of attempting any alteration, from the apprehension that in so doing perhaps the best ingredient of the compound might be removed.-Has Agriculture in this respect attained to clear principles? By no means. Let us read, not indeed books upon agricultural chemistry, but the writings of practical agriculturists themselves; are they agreed upon the modus operandi and the manner of applying the simplest manures, lime, gypsum, humus, ammonia, common salt, &c.? Anything but this. How then can trustworthy precepts be laid down for the method of employing these manures, if no clear notions are entertained respecting their action upon the soil and upon plants?

Thirty or forty years ago phosphoric match-boxes were already known, but they again went out of fashion, on account of their failing to stand the test of long-continued use. Now it would surely have been hasty to infer from this circumstance, that phosphorus was unsuitable for the manufacture of contrivances for instantaneous ignition, since the Lucifer or Congreve matches, now so universally employed, show that it is excellently adapted for this purpose. The reason why the first experiments miscarried lay entirely in the wrong form in which it was applied.-A like state of things has certainly often occurred, in the different results obtained by the application and trial of this or that substance as a manure; favourable results have been secured when, by accident alone, it was made use of in the right form and at the right time, unfavourable ones, on the contrary, when this was not the case. Here therefore a wide and immeasurable field may also be opened to chemico-agricultural investigations.

Comparisons of a similar kind might be instituted in still greater number, but we may be satisfied with these few, which, it is hoped, will suffice to show that chemistry has, at all events, the vocation and inherent capabilities of profitable application to practical agriculture.

That practical knowledge has, nevertheless, in numerous instances opposed, and to some extent continues to oppose, the concession to chemical science, of so much space and time as are necessary to establish and prove its influence, can excite no astonishment; new ideas, which demand an alteration in the existing order of things, have never yet been brought to realization without strife and opposition. Besides, the course which the advocates of science have taken, with the view of introducing them into the affairs of daily life, has not always been correct. It was rash of Theory to bring forward its opinions, ideas, and conjectures as indubitable truths, without previous proof by practical experiment, and forthwith to deduce general conclusions from isolated facts. It was unreasonable in Theory to demand of practical knowledge unconditional faith in the promises it made, and instant surrender of its long-defended standards, to march with drum and fife into the new encampment. It was irrational in Theory to undervalue, and indeed to despise, the lessons of practical experience, instead of turning them to profitable use; and to believe in the possibility of a science becoming practical without an accurate knowledge of the practice appertaining to it, and without a close union with the latter, only possible through such knowledge.

As one extreme invariably produces another, Practice has fallen, in its turn, into the same error. It was hasty of Practice, without experiments, or from a few isolated and defective ones, to pronounce sentence of banishment upon scientific deductions. It was unreasonable in Practice to demand of a science still so young, that it should proceed with the sure and circumspect step of mature age, and to claim from it specific facts instead of principles-recipes, precepts and experimental truths, instead of simple counsel, hints and suggestions. It was irrational in fine to demand from science more than its nature qualifies it to perform.

It is precisely in these points that the path of chemical investigation is obstructed by difficulties, which oppose greatly the perception of the true relations of things and the production of proof by counter-experiment. Here the chemist has not to deal with purely chemical processes, but must laboriously question nature as to what modifications these

processes undergo through the vital force dwelling in plants and animals; he cannot here command fixed, invariable quantities and uniform conditions, so as to test the accuracy of his conclusions, but is as dependent upon soil, climate, wind, and weather, as the farmer himself; and, finally, he cannot here, as in the majority of his operations, institute controlling experiments as quickly and as often as he pleases, but must wait for years before he can draw conclusions.

Under these circumstances, is it fair to judge chemistry by the results it has already accomplished, in the brief space of time during which earnest efforts have been made to apply it to agriculture? Would it not be juster to wait, before delivering an unfavourable decision, until the many buds which it has put forth during the last few years, more particularly through the impulse it has received from Liebig and Boussingault, really prove to be all abortive? Chemistry awaits the arrival of this epoch without apprehension; if many buds and blossoms should fall off its earliest shoots, others will certainly bear fruit, and this fruit will beyond all doubt be very valuable.

Chemistry, moreover, may become of especial use to the agriculturist when he carries on, in addition to mere tillage and grazing, manufactures connected with agricultural produce, such as, distilling, brewing, the preparation of starch or starch-sugar, and the manufacture of sugar from beet-root, &c. Here it has not been found so difficult a task to gain the confidence of the farmer, because the advantages to which it led were so evident, as to admit of direct translation into hard cash. Reasons of this kind have always the greatest power in producing conviction, and they gain acceptance at once. Since chemistry here possesses that which it also desires to gain on the land and in the stable of the farmer, viz. confidence, it would be superfluous to add further assurances, proofs, or illustrations.

The reason why chemistry so soon succeeded here in producing positive vouchers of its utility, lies simply in the fact, that in researches of this kind it has to do, not with living bodies in a perpetual state of change, like plants and animals, but with inanimate substances, which admit of chemical examination more readily than the former. As long as a plant or an animal lives, the chemical processes are under the

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