Domestic Encyclopædia (1802)/Lac

LAC, or Gum-lac, a species of wax, with which the Lac-insect, or Coccus Lacca, L. that frequents several species of the fig-tree, forms cells resembling the honey-combs of bees.

Gum-lac has received various names, according to the different states in which it is obtained. The stick-lac is the wax adhering to the smaller branches of the tree, and which is unprepared. This is first separated from the twigs to which it is attached; and after being grossly powdered, and divested of its colour, by digesting it in certain liquors, is called seed-lac. When the stick-lac is melted over a moderate fire, then freed from its impurities, and formed into cakes, it is denominated lump-lac. The last species is termed shell-lac, and is prepared by liquefying, straining, and reducing the cells into thin transparent plates, in a manner peculiar to the natives of India.

Lac is applied to various purposes of ornament and utility.—Considerable quantities are used in the making of sealing-wax; in japanning; for varnish; and in painting. It also imparts a fine red colour to silk and cotton, when these have previously been immersed in a weak decoction of the bark, known among dyers by the name of load.

Lac is likewise of service as a medicine: for which purpose the stick-lac is in great esteem on the Continent, especially for relaxed and spongy gums, arising from cold, or from a scorbutic habit.—With this intention, it is either boiled in water, with the addition of a little alum for promoting its solution, or it is used in the form of a tincture, prepared with rectified spirit: the latter has a grateful odour, and a bitterish, astringent, though not unpleasant taste, and is chiefly recommended in scorbutic and rheumatic disorders.