inspissated animal jelly; much used as a cement, especially for wood. It is made from various animal substances, according to the uses for which it is designed. Common glue is prepared from the parings of hides, hoofs, and other offal, which are first digested in limewater to free them from grease and all extraneous matter, then washed in water, and afterwards boiled. The viscous solution thus obtained is first strained through a wicker basket, and then gently evaporated to a proper consistence. The heat is generally so regulated as to keep the liquid near the boiling point, without entering into ebullition. The liquid glue is poured into flat moulds; and when it has become firm, it is cut up into square pieces, and placed on a coarse net to dry. Glue improves by age, and that is considered as the best which, if steeped in cold water for three or four days, swells without melting, and resumes its former dimensions after being dried. The clear pale brown glue is the best, though the darker and less pure is often ignorantly preferred. A transparent and beautiful glue is made of the shreds and parings of vellum, fine white leather, or of isinglass. (See also Gelatine.)

A preparation of glue, convenient on account of the facility with which it is rendered fit for immediate use, is made by adding a small proportion of any good spirit, or of wood naphtha, to melted glue. It is to be kept in a well-corked bottle, and when required for use may readily be liquefied by placing the bottle in hot water. It answers all the purposes of ordinary glue.

Indian Glue, as it is called, consists of common glue melted with a little sugar, and moulded for convenience into small flat cakes. When used, the edge of the cake is moistened, and rubbed upon the surfaces to be united. It is a slight cement, used only for such purposes as mending prints, &c.

Jeffery's Marine Glue.—This powerful cement has been most successfully used as a substitute for pitch in the seams of decks, as well as for strengthening large timbers for naval purposes. It is said to consist of caoutchouc dissolved in coal naphtha, to which shellac (previously dissolved in wood naphtha?) in proper proportions is afterwards added. The joinings of built masts secured with this cement are said to have resisted separation by the wedge after ten years' service.

Liquid Glue.—Under this name is frequently sold a cement consisting of shellac dissolved in wood-naphtha.