Dextrine and gum are used by the bookbinder almost exclusively for pasting larger surfaces, and for laying on these substances a broad thin brush fastened with a metal strip is used.
Fig. 1.--Glue-pot for heating by petroleum.
To heat the glue and to maintain the heat a glue-heating apparatus is used. The upper part always consists of the glue-pot. The better kinds are made of copper or brass wrought or moulded in one piece. For the sake of convenience a partition is let into this pot so that thick and thin glue may be ready for use at the same time. The glue is not heated directly over the flame, but by hot water; to do this the glue-pot is placed within a larger vessel containing water, the glue-pot at the same time closely fitting to the outer rim of the larger vessel. This contrivance is placed over a petroleum, gas, or spirit lamp, which gives the required he