a resinous substance formed on various trees in the East Indies by the punctures of an insect (Coccus Laccus), the exuding juice being formed into cells for its eggs. The resin encrusts the branches in grains; these branches, when gathered, are exported under the name of stick-lac; but when the grains are gathered, the colouring matter extracted, and the grains formed into flat cakes, the name of seed-lac is given, the granular appearance being still preserved; when the seed-lac has been melted up and formed into masses, it is called lump-lac or button-lac; when the seed-lac is further purified by melting over a charcoal fire, straining through bags of fine linen, and drying in thin layers on smooth surfaces of wood, it forms shell-lac, known as orange or ruby, according to the colour. The colouring matter of lac is used as a red dye on wool, but is inferior to cochineal. The chief use of lac in Europe is for making sealing-wax, and as a basis for spirit varnishes, and the so-called French polish. Shell-lac is commonly used for the purpose, but as the palest variety contains colouring matter, it cannot be employed for varnishing works of a light colour. It also contains a little wax, and other matters not soluble in spirits of wine, or pyroligneous spirit, which is commonly used for the purpose, the effect of which is to make the varnish cloudy; this is unimportant in varnishing dark coloured works, and may be avoided by making the solution without heat, and decanting the clear portions from the insoluble.
The best stick-lac comes from Siam, that of Assam ranks next, while that of Bengal is inferior. The colouring matter is obtained by pouring warm water on the stick-lac. The colour is made into square cakes, and sold under the name of lac-dye, lac-lake, or cake-lake. There are various methods of bleaching lac, by means of chlorine, animal charcoal, &c. Lac gives the name to, and enters into the composition of, various takers. See Dying, iv., §§ 1, 4; Lacke; and Varnishes.
LA CAILLE. See Caillé, Louis Nicholas de la.