By this Account then we are principally to regard the different Quantities and Degree of Volatility in these Salts, and the Degree of Consistence or Impregnation of animal Oyls with them. It must be observed, that the Salts in the Bodies of living Animals are not perfectly the same they appear to be, when extracted thence by chymical Resolutions; a great Alteration is made by the Fire, and a good deal by the Tendency all animal Substances have to Putrefaction, upon a Stagnation of their fluid Parts: Even in the Evaporation of human Blood (fresh drawn) by a gentle Fire, this Salt, though not perfectly fixed, will not rise, but only the Spirit: These Salts are of a mild attenuating Nature in healthy Bodies, whose vital Powers are sufficient to subdue the Substances they feed upon: But in such as have not that vital Power in that Degree, or commit Errors in Diet, where these Salts are not sufficiently attenuated, or the first Digestion stronger than the concoctive Powers or the Discharges, these Salts acquire Properties productive of many acute and chronical Diseases; (not within the Compass of this Enquiry) these may be prevented, and sometimes cured, by a strict Application to Diet, proper to correct the different Modifications of these Oyls and Salts. I own it is pretty Difficult to determine the exact Degree of Volatility these Salts acquire in any particular Animal, or in different Parts of the same Animal; yet there are very evident Marks of a Defect, or Exceeding in the Volatility of these Salts, by examining the Discharges from Animals, by a greater or less Tendency to Putrefaction, by several Distempers more especially incident to human Bodies, and other Methods of Art to be met with in the History of Physick. From what was said before, it is evident that an Animal, whose Juices are supplied from animal Juices, hath a more alkalescent Tendency than an Animal supplied with vegetable Juices; that is, the Salts are more highly volatilized, and impregnate the Oyls, Water, and other Fluids in a stronger Manner, and in greater Quantities; and in Fact, we find the Substance of such animal Bodies, as are fed upon Animals, or Use stronger Exercise, are more liable to Putrefaction, than the Substance of Animals that feed upon Vegetables, and are more slothful. Fish, Foxes, Hawks, Venison, Horses, have their Substance more liable to Putrefaction, and discover to our Senses more exalted Salts and Oyls, than tame Fowl, Sheep, and Oxen; the Juices of poisonous Animals have them still more exalted, as in the Viper.