SECT. 7.
The Liquor that is separated from these Glands is a Mucilage, not unlike the White of an Egg, tho’ not always so clear and pellucid; when pure it is very like it. In some Animals it is of a Colour inclining to Yellow, and is composed of watry, saline and slimy Particles; it is supposed that the earthy Particles may be about a two and thirtieth Part. The Nature of this Mucilage seems nearly to approach to that of the Serum of the Blood, separated from the grumous Part upon being exposed to the Air, and exhibit much the same Appearances upon Trials by Mixture with other Bodies, only the Serum is not so mucilaginous. The Serum is coagulated upon being mixed with Spirit or Oyl of Vitriol, Spirit of Salt, Oyl of Sulphur, and other acid Spirits. The Serum, upon being held in a Spoon over the Fire, becomes a thick Jelly, and at length a sort of friable Glew; on the contrary, the Mucilage grows thinner, upon the same Application, throws up a slight thin Film at Top, and produces but a slight Coagulum. After the aqueous Parts are evaporated, there remains scarce a thirtieth Part of the whole Mass.