Spirit of wine will not dissolve the gummy parts of vegetables; and by this means the gummy substances may be separated from their solutions in water, the spirit uniting with the water only. On the other hand, if resins be dissolved in spirit of wine, the affusion of water will separate them. By means of the affinity of spirit of wine with water, it will seize upon the water in which several salts are dissolved, and thus produce an instant crystallization of them. Salt of tartar has a greater affinity to water than spirit of wine, and by extracting water from it, will assist in concentrating it; but the best method of rendering spirit wine free from water is distillation, the ardent spirit rising before the water. Spirit of wine mixed with the vitriolic and other mineral acids, renders them milder, and thereby more proper for certain medicinal uses. This is called _dulcifying_ them. Spirit of wine is a powerful antiseptic, and is therefore of use to preserve vegetable and animal substances from putrefaction. _Of AEther._ If spirit of wine be distilled with almost any of the acids, the produce is a liquor which has obtained the name of _AEther_, from its extreme lightness and volatility, being much lighter, and more volatile, than any other fluid that we are acquainted with. It is highly inflammable, but the burning of it is accompanied with smoke, and some soot; and on this account it is a medium between spirit of wine and oil, the acid having taken from the spirit of wine part of the water that was essential to it, at the same time that it communicated something of its acid peculiarly modified; since aethers have different properties according to the acids by which they are made; as the _vitriolic_, the _nitrous_, the _marine_, and the _acetous_. No aether, however, can be made from the marine acid till it has been in some measure dephlogisticated; from which it may be inferred, that dephlogisticated air is necessary to the composition of aether. Vitriolic aether is the most common, in consequence of the process by which it is made being the easiest. AEther does not mix with water in all proportions, like spirit of wine, but ten parts of water will take up one of aether. It easily mixes with all oils. It is something remarkable, that though aether will not dissolve gold, it will take from aqua regia the gold that has been previously dissolved in it. By the quick evaporation of aether a considerable degree of cold may be procured; and on this principle it has sometimes been applied to relieve the head-ach and other pains. LECTURE XVIII. _Of Oil._ Oil is a liquid inflammable substance, of great tenacity, disposed to pour in a stream rather than in drops. It is little, if at all, soluble in water. It burns with smoke and soot, and leaves a residuum of a coaly substance. It consists of acid and water combined with phlogiston.