Liquid Glue. Several preparations are much in vogue. The liquid glue of the shops, however, is a totally different prepa-ration, being inodorous, and very much cheaper. It is made by dissolving shell- lac in water, by boiling it along with borax, which possesses the peculiar property of causing the solution of the resinous lac. This preparation is convenient for its cheapness and freedom from smell, but it gives way if exposed to long-continued damp, which that made with naphtha resists.
Common Glue should always be prepared in aglue-pot or double vessel to prevent its being burned, which injures it very materially ; the objection to the use of this contrivance is, that it renders it impossible to heat the glue in the inner vessel to the boiling point; this inconvenience can be obviated by employing in the outer vessel some liquid, which boils at a higher temperature than pure water, such as saturated solution of salt, (made by adding one-third as much salt as water). This boils at 224° Fahr., 12° above the heat of boiling water, and enables the glue in the inner vessel to be heated to a much higher temperature than when pure water is employed. If a saturated solution of nitre is used, the temperature rises still higher.
Limb and Ego Cement is frequently made by moistening the edges to be united with white of egg, dusting on some lime from a piece of muslin, and bringing the edges into contact. A much better mode is to slake some freshly-burned lime with a small quantity of boiling water; this occasions it to fall into a very tine dry powder, if excess of water has not been added. The white of egg used should be intimately and thoroughly mixed, by beating, with an equal bulk of water, and the slaked lime added to the mixture, so as to form a thin paste, which should be used speedily, as it soon sets. This is a valuable cement, possessed of great strength, and capable of withstanding boiling water. Cements made with lime and blood, scraped cheese, or curd, may be regarded as inferior varieties of it. Cracked vessels, of earthenware and glass may often be usefully, though not ornamentally repaired by white lead spread on strips of calico, and secured with bands of twine. But in point of strength, all ordinary cements yield the palm to
Jeffery's Patented Marine Glue, a compound of Indian-rubber, shell-lac, and coal tar naphtha. Small quantities can be purchased at most of the tool warehouses, at cheaper rates than it can be made. When applied to china or glass, the sub-stances should bo cautiously made hot enough to melt the glue, which should be then rubbed on the edges so as to become fluid, and the parts brought into contact immediately. When well applied, the mended stem of a common tobacco-pipe will break at any other part in preference to the junction. The colour of the glue unfortunately prevents its being used.