CHEMICAL FIELD LECTURES.

I. CHEMISTRY, THE FARMER'S HOME-FRIEND.

In all time, past and present, two great wishes have been entertained by man; namely, to remain always young and healthy, and to possess wealth sufficient to satisfy all his desires. Obscure tradition intimated that a wondrous jewel, which possessed the power to fulfil both these wishes, was hidden somewhere in Nature, or might be distilled from her products. By its assistance, it would be an easy task to convert lead into gold, and to prepare a vital elixir which would abolish sickness, and, in all probability, even death itself. A thousand years was this treasure sought for, but never found. At length, however, something was discovered; not indeed the philosopher's stone, but in its stead a new science, CHEMISTRY.

Scarcely eighty years have elapsed since this discovery, but already the new science has gained an importance in the affairs of daily life, and an influence upon the material welfare of man, consequently also upon the state of civilization, which cannot but excite astonishment. To a certain extent, chemistry really possesses the power ascribed to the philosopher's stone; for by chemical knowledge many a manufacturer has converted, although in a manner less direct, masses of the common metals into precious gold; and by chemical therapeutics many a sufferer has recovered health. The complete annihilation of disease, it certainly has not yet been able to accomplish.

The rapid diffusion of chemical science has been chiefly owing to the numerous and diversified uses to which it can be applied in every-day life. Chemistry teaches the apothe

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cary how to prepare his remedies; the physician how to banish sickness by means of these; and it not only reveals to the miner the metals hidden in the rock, but aids him in their extraction and refinement. Chemistry, in conjunction with physics, has been the principal lever by which, within the last ten years, so many arts and manufactures have been raised to such extraordinary perfection; by its means innumerable comforts and conveniences of life, of which our forefathers were destitute, have been afforded us. results which might be brought about by natural forces, whose existence was unknown until revealed by chemistry, especially in the circle of the useful arts, were so self-evident, that a door was here very soon opened to it. And although sturdy practical knowledge regarded its occasionally rather airy and high-flown theories at first with some distrust, a closer acquaintance with it has now changed those misgivings into entire confidence, and led to an intimate fellowship and union of the two.

In the last few years, chemistry has applied all its force to the investigation of the constituent elements of the organized bodies of plants and animals, and to an examination of the processes which go on in them during life as well as after death. Of what do these bodies consist? Whence do they acquire their component parts, their sustenance ? What changes must the latter undergo in the living organisms of animals and plants, in order to produce their nourishment and growth? How can man accelerate this growth? These are the principal inquiries which chemical research strives

to answer.

May we actually expect to derive real advantage in the field of practical agriculture from investigations of this kind? Chemists, and many agriculturists, especially such of the latter as possess chemical knowledge, are fully convinced that this may be looked for; from other quarters, on the contrary, doubts, at one time feeble, at another stronger, are still heard, as to their utility to the farmer. To arrive at a right decision upon any subject, it must first be accurately understood; for otherwise the primary foundation of a correct judgment is wanting. Many of those doubters have still, perhaps, no clear idea of the true nature, objects, and powers of chemistry; and for this reason it will conduce

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to the end we have in view, to premise a few observations upon the nature and objects of this science, as also upon ways and means by which it seeks to attain its aims.

Everybody knows that a piece of iron, when hammered at a red heat, is converted into black scales, while by exposure to the damp atmosphere, or burial in moist earth, it is changed into rust; that the expressed juice of the grape is gradually transformed into wine, and this, again, into vinegar; that wood in a stove, or oil in a lamp, disappears when burnt; and that animal and vegetable substances in time become putrid, disorganized, and finally, in like manner, disappear.

Iron scales and rust are altered iron: iron itself is hard, tough, of a grayish-white colour, and brilliant; when heated to redness it becomes, with an increase of its specific gravity, black, dull, and brittle; when kept in a moist atmosphere, it is converted into a brownish-yellow powder. Wine is altered juice, or must, in which the sweet taste of the grape-juice can no longer be perceived; it has acquired a spirituous flavour, and possesses heating and intoxicating properties, which did not exist in the must. Vinegar is altered wine: it has a sour and not a spirituous taste and odour, and, when taken as a beverage, acts no longer as an intoxicant, but as a refrigerant and sedative. We must look in the atmosphere for the wood or oil which have disappeared in combustion, for by this process both these substances are converted into vapour or gas; in this transformation heat and light are simultaneously produced; it is accompanied by the phænomenon of fire. The alterations which animal and vegetable substances undergo when kept for a long-continued space of time are of similar nature; they are gradually converted, as they putrefy or decay, into gases of various kinds, some of which possess a very disagreeable odour.

Such processes, by which not merely the external form, but the whole essential nature, of bodies are changed, are called chemical processes; by their agency, often accompanied by the phænomena of heat and fire, bodies are so fundamentally altered in weight, form, solidity, colour, taste, smell, action, &c., that new bodies with entirely new properties are produced. Wherever we look upon our globe, we behold chemical action on the land, in the air, in the depths of the sea; in the inanimate mineral, no less than in the living animal and

vegetable kingdoms. The hardest stone becomes gradually friable, changes colour, crumbles into smaller and smaller fragments, and at length forms earth. A potato when planted in the ground becomes soft, acquires a sweet taste, then it rots, and at last entirely disappears. Yet this apparent annihilation is only a chemical metamorphosis; from the offensive products of putrefaction the creative force of nature produces a fresh plant, full of new life, together with all the varied substances occurring in it, such as sugar, starch, oil, &c.

The tubers of the potato-plant form one of our most important articles of food. The starch contained in them is insoluble in water, but when received into the stomach, rapidly undergoes such a change that it can be dissolved or digested, and then introduced as a liquid into the blood. In the lungs, the blood comes into contact with the inhaled atmospheric air; it is thereby changed in colour, and the air also in its constitution, the heat developed through these alterations being the source of that warmth we feel in our bodies. Hence it is evident that chemical action takes place in our own frames, as in those of plants; the plant, the animal, and in no less degree Man himself, are composed of chemical substances, and it is through chemical processes, not only that their nourishment is prepared, but digested and converted into animal or vegetable substance. Finally, when life has ended, chemical processes again, as the grave-diggers of nature, accomplish the fulfilment of the old truth, "What is of the earth, to earth shall again return."

Indeed, if we only look around within the narrow circle of our every-day life, we shall be reminded at every moment, by our necessities and occupations, of the beneficial results of chemistry. The clothing which we wear has been prepared by its instrumentality; not that the tailor, who made our coat, was himself a chemist, but the cloth was bleached, dyed, and dressed by chemical processes. The soap with which we wash is a chemical preparation; the fire at which we warm ourselves, and the light wherewith we illuminate our evenings, are both produced by chemical action. Chemistry, then, proposes to ascertain the way and manner in which these internal or chemical changes take place, the cause of their occurrence, and the laws in conformity with

which they happen. To effect these objects, it must first of all learn of what those bodies, whose changes it desires to study, are composed; it therefore decomposes, separates, or analyses them, and thereby arrives at the knowledge of their constituents. For this reason it was formerly called the Art of Analysis (Scheidekunst, art of separation). The simple bodies or substances thus discovered, which could be decomposed no further, have received the name of chemical elements, or elementary substances.

In contrast to decomposition or separation, stands combination or uniting together. It was very natural that the chemist should attempt to rebuild that which he had torn down; that he should endeavour to imitate by artificial means the chemical changes taking place in nature; and that he should try whether it was not possible to produce new bodies and chemical changes besides those already existing in nature. Hence chemistry derived its second appellation, the Art of Combination (Mischungskunst, art of mixture). The numerous discoveries and inventions with which these experiments were crowned are too well known to require mention of examples.

So long as chemistry did not inquire, in its analyses and combinations, into the weight and measure of ingredients, it remained little more than a mere art of testing; it did not become a science until the habit was acquired of instituting chemical researches with the balance in hand. This instrument is to the chemist what the compass is to the mariner. The ocean had indeed been navigated before the discovery of the compass, but to continue steering with certainty to a particular point, and to recover the proper course, however often it might be lost, was impossible to the navigator until the magnetic needle was put into his hands. And so, in chemistry, no predetermined plan or systematic course of investigation could be confidently pursued, until the introduction of the balance. The balance, which furnishes both a guide and touchstone for chemical experiments, first gave to us, among other things, the certainty--which forms the very foundation of chemistry-that all chemical combinations and decompositions take place only in accordance with fixed and unalterable measures and weights. This certainty we regard as a natural law.