cases extremely light and rare, as in smoke, vapour, and the lightest fluids. Chemistry is a dangerous field for speculation; it is a science where art runs so many divisions upon nature, and the active elements do so interfere with and disguise the others, that the chemist who resolves to be a philosopher upon his own ground, is very soon bewildered, and becomes visionary in his reasonings. and principles. I think it easy enough to discover the four elements in nature itself; but when I go to look for them in books of chemistry, they are so overlaid with a multiplicity of experiments, that it is not always possible to extract any thing consistent from them; and therefore we should be cautious of meddling too far with an art which hath betrayed so many into the enthusiasm of alchemy. Upon the whole, we do not find any suf ficient ground to determine, that the elements generally acknowledged will not account for all the compositions in the mineral kingdom. If we proceed from thence to the vegetable, the case will be plainer still; and if to the animal, plainest of all. What is the sap of plants, but water, almost simple in some cases, in others more or less less impregnated with saline or unctuous particles? Whence do plants derive their firmness and solidity, but from earth, to which they are all reducible when consumed in the fire? And then they are joined with the matter of the mineral kingdom, in the composition of glass. When they are laid to putrify, a vast quantity of air is detached from them; and we know not how to account for the acrid taste, the aromatic and caustic qualities of many vegetable juices, but from the fire combined with them; nor for the inflammability of resinous ever-greens, but from the same cause. How far the fire of that ardent spirit, which is obtained from fermented vegetable juices by distillation, resided in the substance of the vegetable matter itself, should also be considered: but certainly it cannot all be derived from the fire applied in the operation. When the matter of vegetables is volatile, as much of it is found to be, this volatility must be ascribed to air and fire attached to it, without which neither the earthy nor the watery parts can ascend and fly off. In animals we find the same principles as in vegetables, but differently combined and qualified. The basis of their substance is an earth, earth, most distinguishable in the bones, the ashes of which are not fusible in the fire, nor capable of running into glass; and therefore proper to make such chemical vessels as are used for the assaying of metals, and are necessarily exposed to the utmost violence of fire. Of all the fluids in the body, water is the principal ingredient. When blood is set by to cool, it separates into a lymph or serum, very little differing from water, and almost insipid; the remainder is a coagulated mass, consisting of the red globular particles of the blood, which are composed chiefly of earth, and, when distilled to dryness, may be reduced to ashes. The inflammability of animal oil or fat, shews that fire is fixt in it; and the production of that remarkable body, the phosphorus of Kunkel, which is made of putrified animal juices, is another proof that fire is an ingredient in the animal frame. The vapour which rises from the body in perspiration, is a farther proof that fire is present in it, because water never becomes volatile but from a mixture of fire, at least when there is any perceptible heat with it, as in the present instance. The vapour which rises from the intestines of an animal newly killed, killed, is so inflammable, that it hath been frequently observed to take fire at a candle, A very large quantity of fixed air is disengaged from the body of an animal when it putrifies; and this is the reason why bodies become specifically lighter, and float in the water after they have lain under it a few days, appearing big and swoln as if they were inflated with wind. The four usual elements are therefore the ingredients which discover themselves when the human body is decomposed, and it doth not appear that there are any others: all the oils, salts, and saponaceous humours, may be accounted for from the properties of fire and air, combined with earth and water. The body of man, which is at the head of the material creation, and hath always been understood by theorists as a lesser world, analogous to the greater, is sufficient by itself to confirm and illustrate our doctrine of the four elements. His bones, when the oil and phlegm are extracted, are elementary earth; his blood is a red earth floating in an insipid water as its vehicle. His vital motions are maintained by the heat of an internal fire, and the breath of his life is the element of air. Here Here it may be entertaining, and not altogether useless, to look back to the philosophy of the ancients, and take a view of their doctrine concerning the elements. They did not think it necessary to have recourse to the operations of chemistry, when they found the elements already distinguished to their hands in the constitution of nature. If we consider the order of things in the frame of the world, we find the body of the earth situated first and lowest in order, over which the water is spread, as being lighter and more moveable; next above the water is the air or atmosphere; and, above that, a purer region, to which they gave the name of fire. In respect of their weight, they naturally dispose themselves into this order: earth takes its place below water; water subsides in air; and air itself, less rarefied by fire, sinks below that which is more so. If we begin the other way, fire rises in air; air rises in water; water rises from earth. However, though the elements range themselves into a natural order, we cannot absolutely say where one of them ends and the other begins, because they are blended together, and tempered so as to be subservient to each other for the good of the whole. The solid orb |
