Acid Soaps are decompounded by alkalis, as alkaline Soaps are by acids, according to the general rules of affinities.
The acids of nitre and vitriol, when highly concentrated, dissolve Oils with such violence as to heat them, make them black, burn them, and even set them on fire. How sea-salt affects Oils is not yet sufficiently ascertained.
All Oils have the property of dissolving sulphur; which is not at all surprising, seeing each of its component principles hath an affinity with Oil.
It is also a property common to all Oils to become more fluid, subtile, light, and limpid, the oftener they are distilled. On the contrary, by being incorporated with saline substances they acquire a greater consistence, and sometimes form compounds that are most solid.
[CHAP. XI.]
Of the several Sorts of Oils.
Oils are distinguished by the substances from which they are drawn: and as Oils are extracted from minerals, from vegetables, and from animals, there are of course Mineral, Vegetable, and Animal Oils.