Glue

an adhesive substance obtained from the refuse of tanneries and packing houses. Roughly speaking, glue is obtained from a mass of fish scale or of horn, hoof, bone, sinew, and hide by first cleaning the pieces with lime and then boiling or steaming them for a considerable length of time over a false bottom or gate which permits the glue to drain off as it is released from the animal tissue. As the glue runs away it is caught, cooled, and, when "set," it is cut into cakes and sliced into shavings which are dried thoroughly and placed on the market. Glue factories are near neighbors to the packing houses of the corn belt and to the salmon canneries of the Pacific coast.

Glue is used chiefly by carpenters and cabinetmakers, and by sash and door factories in gluing pieces of wood together. Doors are made frequently with a veneer of hard wood on one side and a veneer of soft wood on the other. Two boards glued together under strong pressure are likely to split elsewhere before the glue will give way. The tops of tables, school desks, seats of wooden chairs, and most wide woodwork is made of narrow pieces glued together under strong pressure. Carpenters soften glue for use in a glue-pot. An inner pot containing the glue hangs in an outer pot containing water, so that the glue receives a slow, constant heat.

Glue is used by silk makers and in the manufacture of rigid linings to give a required degree of stiffness. It is used also by paperhangers to "size" or prepare walls for the reception of paper.

Mucilage is more often prepared from vegetable substances. An excellent article, none better, may be made from gum arabic, four ounces; honey, one and one-half ounces; and water, one pint.

The earliest American glue factory was established by Peter Cooper at Brooklyn in 1827. The present American output is valued at about $6,000,000 a year. The finest glues are made in France. Sinews alone are used for the first quality of glue.

See Packing House; Gum; Gelatine; Isinglass