of medicine were subjected by the followers of Baglivi, Keil, Mead, and the mathematical physicians, to algebraic and fluxionary calculus, and the vis inertiæ of all inanimate matter, was regarded as a fact indisputable, as an essential property of all matter, whether the subject under consideration were a man, a molecule, or a mountain.

By degrees, however, philosophers began to discover that the motions of the animal system, and the operations of medicine, could not be explained by calculations merely mechanical-that the laws which regulated the changes of inanimate matter out of the body could not be applied to the same substances within the body-that the conditions of health and disease formed a problem not to be solved from the nature of animal fluids considered merely as fluids-from any capillary attraction a parte ante or any propulsive force a tergo-but that a principle not well understood though sufficiently manifested by its effects, to which the name of stimulus has since been given, operated on the living solids, and produced actions and changes peculiar to itself, and beyond the reach of the known laws to which natural philosophy had hitherto resorted. This paved the way for introducing the awkward chemistry of the time into medical theories; and the spheres, and spicule of the mechanical physicians gave place for a time to acidity and alkalescence.

Again. It began about the same time to be observed, that the minute particles of bodies, attracted and repelled each other; and when brought within the sphere of mutual activity, produced on each other, changes, decompositions, recompositions, and new compositions, which were neither consistent with a supposed vis inertiæ, or explicable by any calculations that mathematical science could bring to bear upon the phenomena: that, almost every natural object and appearance, the rain, the hail, the sunshine, fire, air, and water, ice and snow, earths, metals, and minerals-the intestine motions and changes underneath the earth's surface, and those that took place upon and above it-every object of nature, every composition of art-every trade and manufacture (exclusive of mere instruments and machinery) were dependent on principles, which what is called natural philosophy could not grasp, and knew not how to apply, or explain. Hence a new branch was added to natural philosophy, whose ancient boundaries were now enlarged; this new branch was the science of chemistry, for many ages despised and neglected, but found at length to be of more extensive use, and application, than all that had been known before. Hitherto philosophy had kept aloof from the common concerns of life. Chemistry introduced her into every workshop, and made her an iamate of every family. All science that has practice for its object, is first known as an art. When by long usage, facts are accumulated, men of reflection begin to com

COOPER ON CHEMISTRY.

pare and arrange them, and deduce principles or laws to which the operations of art may be considered as subjected; and by means of these general laws, new practices and operations are suggested, foreseen, and tried. Chemistry as an art, was known to the Hindoos, to the Phenicians, to the Egyptians, to the Arabians on the decline of the Roman empire, to the Alchemists and Rosicrucians during the middle ages, but it did not properly become a science till a few years previous to the period of our American revolution, when the discoveries of Black, Scheele, Priestley, Lavoisier, and Cavendish, fixed it on an independent basis as a science of the very first importance, whether studied as an object of curiosity, or with a view to its practical application.

Indeed, machinery excepted, it is to chemistry we must look up with any well grounded expectation of future improvement in agriculture, in the elegant or useful arts, or in manufactures; with arts of mere fancy, such as poetry, painting, architecture, or music, we have at present nothing to do. This will be more evident, by passing in review those arts and manufactures that tend to render human existence more desirable, by contributing to ornament, to use, to comfort, to pleasure, to economy, or to convenience: those arts and manufactures that we resort to for our houses, our furniture, our clothing, our food, our means of conveyance, our health, If chemistry shall appear to have a direct bearing or our amusements, on all these objects, who will assign it a second place among the important branches of human knowledge?

The earth is the rerum magna parens, the great source of every material that man converts to his sustenance, his comforts, and his pleasures. AGRICULTURE is the art of raising food from the earth: but the earth also supplies timber and stone for building, metals and minerals for working, medicinal waters for the cure of diseases, and varieties of soil, adapted to the various purposes of human existence,

In all its branches, agriculture is also a branch of chemistry.

Do you want to raise food? This must be done 1st, by a judicious application of the kind of soil you possess to the kind of vegetable adapted to it. Who would plant rice on the top of a mountain, or the vine in a swamp, cabbages in a hungry sand, or carrots in a stiff clay? 2ndly. In properly mixing the soils your farm affords, as clay with sand, and sand with clay, and both with calcareous earth, so as to afford a mixture easily penetrable by the roots of plants, stiff enough to support them, and ablę to retain sufficient of the moisture of the atmosphere, and of manures, to afford this kind of nutriment to the vegetables planted in them. 3dly. The agriculturist will have to consider what manures afford nutriment directly to the plant, as bread and meat constitute the pabulum of a human

creature, and what manures act by simply stimulating and enabling the plant to take up and digest more nutriment than it would otherwise do; as a glass of wine, and the condiments salt, pepper, vinegar, &c. act as stimuli to the human palate and organs of digestion. Thus, water, hydrogen gas, carbon, carbonic oxyd, carbonic acid, ammoniacal gas, are substances that a plant can decompose and feed upon, assimilating a part of them in the form of nutriment to its own substance, while lime, ashes, gypsum, epsom salt, common salt, and some others, being applied in small quantities to the roots of plants, act almost entirely either as septics, or as condiments and stimuli, enabling the plant to eat and drink more heartily, both from the earth below, and the atmosphere above, and to digest more perfectly also than otherwise it would do; but contributing little or nothing to the substance the weight and bulk of the plant itself. 4thly. He will have to consider what noxious saline substances exist in his soil, as the salts of iron or magnesia, and of course what chemical affinities are to be brought into play, to decompose them, as lime or the magnesian lime are applied to the sulphats of iron. 5thly. He will have to give some intelligible nomenclature to soils dependent on their component parts; and avoid confounding, as is commonly done, clay with loam, marle with clay, limestone soil with argillaceous soil, &c. so that by knowing the elements of which his land is composed, he may know on sure ground how to mix and how to manure them. 6thly. The land owner will seek to know the contents of his farm, not only for the plants he can raise upon it, but also for the uses to which he can apply the timber that grows upon it. The properties of those trees that yield a resinous juice and little alkali, as the various species of pines, those that yield a saccharine juice, as the birch, the maple, and the hickory, those that yield a pysoligneous acid as the various species of oaks, those that abound in tannin for the use of tanners, or in the astringent acid for the use of dyers, those woods that bear exposure best to air without rotting, those that last best in water, the use of charring the outside of wood, and many other particulars, all dependent on chemical qualities or chemical practices, are objects of material consequence to the land owner. 7thly. He will have to attend to the various kinds of earths and other minerals that his farm may contain, whether for common or ornamental building-to examine the indications of salt, of coal, of gypsum, of allum, &c.—to search what mineral waters may arise in the land, &c. all which can only be ascertained by a competent portion of chemical knowledge; and although a farmer or land-owner may assuredly live without it, he will as certainly employ his time and his means to a much better purpose if he should be previously instructed in the science that will enable him to ascertain these facts, whether for the purposes of curiosity, of plea

sure, or of profit. The builder, whether in stone or in brick, may greatly profit by a knowledge of chemistry. Of stones, some are more porous and have a greater affinity to moisture than others; some transmit and some condense moisture sooner than others; some decay in whole or in part sooner than others. So of brick; bricks, as they are commonly burnt, will absorb about half a pint of water when immersed in it: hence the damp on internal walls, the spoiling of ornamental paper, and the necessity of battening. In the making of bricks also, they will always be imperfect if the brick earth contain any calcareous earth, even in small lumps, while on the other hand, the bricks will run into a porcellaneous fusion, if calcareous earth in a very comminuted state be intimately mixed with the clay exposed to violent heat. So in the making of mortar, if a ton of limestone be returned in a greater weight than eleven hundred weight of lime, it is ill burnt, and the mortar will be imperfect: if it be kept for many days before it is transported to the place where it is to be used, air and moisture will be imbibed in great quantities, the weight will be unnecessarily increased, and the lime injured exactly in the same proportion. So in the choice of sand, unless it consist entirely of siliceous earth without any intermixture of argillaceous, unless it consist of angular siliceous chrystals instead of small rounded pebbles, it will not make mortar in its first state of perfection, nor will the workman know the proper proportion to mix with the lime for the purpose of making good mortar. In like manner, in the making of water cement with terras or puzzuolana, in the substitution of the oxyds of iron or manganese for terras; in the making of scagliola for coloured stuccoes and the imitations of marble-in the proper use of gypsum to intermix with lime in the common stuccoes, and for plaister mouldings—defects of materials, and methods of practice, with the reasons whereon they are founded, are obvious to a man possessed of chemical knowledge, which remain concealed from, and are unintelligible to the architect who does not possess it.

The preparation of all our food, depends greatly as to its salubrity, economy, and perfection, on chemical knowledge: such are the trades of a BREWER, a WINE MANUFACTURER, a VINEGAR MAKER, a DISTILLER, a BAKER, and though last, not least in importance, a cook.

The whole business of malting is a process purely chemical, and consists in the conversion of vegetable ficula into saccharine matter by means of partial germination. The use of the thermometer in regulating the process of malting-in ascertaining the temperature at which water will best take up the soluble parts of the malt-the heat at which the malt will set and become insoluble-the heat at which the liquor may be turned out of the coolers into the fermenting vat, when compared with the

strength of the worts as ascertained by the saccharometer are all so many chemical suggestions and processes which have given a new face to the whole of the business of brewing, and enabled the artist to furnish a better beverage, with more certainty and at less expense from the same materials, than when these practices were unknown. The manufacturer of wine, whether from the raw grape or the dried grape, is under equal necessity of understanding the theory of fermentation, and the precautions necessary to manage it: for unless he has studied the elementary doctrines of fermentation as dependent upon chemical principles, he will never be able to regulate his practice with any degree of certainty: anomalies will arise that he cannot explain, and results will be different, when, to all appearance, the processes have not varied. This in common practice, is so well known to every wine maker and distiller, that it is a subject of frequent remark and general complaint. Much still remains to be ascertained and many improvements to be made in this difficult branch of manufacture, but whatever the defects may be, it is chemical science alone that must explain the imperfections, and suggest the remedy.

In the process of making vinegar, which depends on the decomposition of mucilage, and the oxydation of saccharine matter and of alcohol, the whole of it is a process purely chemical; and so is the analogous process of procuring and purifying the pyroligneous acid, which may hereafter supersede the common acetous acid, for every purpose to which the latter is now applied.

In the distillation of grain, all the difficulties that arise in brewery, are experienced. The same thermometrical care to prevent the setting of the grain, the same attentions to the fermentation, the same precautions against the conversion of the new formed alcohol into vinegar, are to be taken in both cases: and the methods of impregnating the spirits produced with the various flavours required, are purely chemical proces

ses.

This business still requires experiments as to the quantity of ferment necessary to liquor of a given temperature and a given specific gravity as to the necessity of covering the fermenting vessels at certain temperatures as to the modes of hastening and checking fermentation— and also to ascertain whether it be the fecula of the grain-the starch that can be washed away, or whether it be the tough insoluble part of the flour that remains, that contributes most to the formation of alcohol. It should seem that increasing the fecula in proportion to the gluten would be an improvement. The same set of experiments are necessary also to the BAKER: whether the bread be better flavoured and more nutritious in proportion to the starch contained in a given quantity of flour, or capable in the same proportion of more permanent combination with mois