With this view the mixts to be decomposed are forcibly compressed, in order to squeeze out of them all such parts of their substance as they will by this means part with: or else those mixts are for a long time triturated, either along with water, which carries off all their saline and saponaceous contents, or with solvents, such as ardent spirits, capable of taking up every thing in them that is of an oily or resinous nature. We shall here give a succinct account of the effects of these different methods, as applied to the principal substances among Vegetables and Animals, and likewise to some Minerals. SECTION I. _The_ ANALYSIS _of_ VEGETABLE SUBSTANCES. A vast many vegetable substances, such as kernels and seeds, yield, by strong compression, great quantities of mild, fat, unctuous Oils, which are not soluble in ardent spirits: these are what we called _Expressed Oils_. They are also sometimes called _Fat Oils_, on account of their unctuousness, in which they exceed all other sorts of Oil. As these oils are obtained without the aid of fire, it is certain that they existed in the mixt just as we see them, and that they are not in the least altered: which could not have been the case had they been obtained by distillation; for that never produces any Oils but such as are acrid and soluble in spirit of wine. Some vegetable matters, such as the rind of citrons, lemons, oranges, _&c._ also yield, only by being squeezed between the fingers, a great deal of Oil. This spirts out in fine small jets, which being received upon any polished surface, such as a looking glass, run together and form a liquor that is a real Oil. But it must be carefully noted, that this sort of Oil, though obtained by expression only, is nevertheless very different from the Oils mentioned before, to which the title of _Expressed Oils_ peculiarly belongs: for this is far lighter and thinner; moreover, it retains the perfect odour of the fruit which yields it, and is soluble in spirit of wine; in a word, it is a true essential Oil, but abounds so in the fruits which produce it, and is lodged therein in such a manner, occupying a vast number of little cells provided in the peel for its reception, that a very slight pressure discharges it; which is not the case with many other vegetables that contain an essential Oil. Succulent and green plants yield by compression a great deal of liquor or juice, which consists of most of the phlegm, of the salts, and a small portion of the oil and earth of the plant. These juices, being set in a cool place for some time, deposite saline crystals, which are a combination of the acid of the plant with part of its oil and earth, wherein the acid is always predominant. These salts, as is evident from the description here given, bear a great resemblance to the tartar of wine treated of above. They are called _Essential Salts_; so that Tartar might likewise be called the _Essential Salt of Wine_.