(From gelo, to congeal). Gelatine is an ingredient in the vegetable as well as the animal kingdom; though the former is more properly styled gum or mucilage. It is transparent, soluble slowly in cold water, and rapidly at 90°. Alkalis dissolve it, especially when assisted by heat; acids more rapidly. With the nitric acid it is partly converted into malic and oxalic acids. It is insoluble in alcohol; but a small portion may be added to the watery solution without any precipitation.

With tanin, a yellowish white precipitate is thrown down from a solution of gelatine, which forms an elastic adhesive mass, not unlike vegetable gluten, and is a compound of the tanin and gelatine. Indeed the tanin is the most certain test of mucilage in any body. By heat it is decomposed, and yields, in a retort, ammonia, a foetid oil, zoonic acid, and a porous charcoal, leaving phosphat of lime, muriat of soda, and potash.

Gelatine soon becomes sour, and quickly putrefies. The animal mucilage, which greatly resembles it, is not precipitated by tanin, nor does it become a jelly by evaporation. The jellies of ripe fruits are denominated only from their consistence, which is obtained by sugar.