[Fr., from L. gelatus, frozen.] An animal substance of a nitrogenous nature, supposed to be closely connected with the albuminous substances. It does not exist already formed in the animal tissues, but is obtained by the action of boiling water on connective tissues, cartilage, ligaments, and tendons. When its solution in boiling water cools, it forms a tremulous jelly. It is nutritious, and much used in soups and jellies. It dissolves in hot water and in acetic acid, but is insoluble in alcohol. It is largely used in many photographic processes. A powerful explosive known as explosive gelatine is made by dissolving 5 parts of gun-cotton in 95 parts of nitro-glycerine gently heated in a water-bath. (See Isinglass.)