LAC  , a resinous incrustation formed on the twigs and

young branches of various trees by an insect, Coccus lacca, which infests them . The term lac (laksha, Sanskrit; lakh, Hindi ) is the same as the numeral lakh—a hundred thousand—and is indicative of the countless hosts of insects which make their appearance with every successive generation . Lac is a product of the East Indies, coming especially from Bengal, Pegu, Siam and Assam, and is produced by a number of trees of the species Ficus, particularly F. religiosa . The insect which yields it is closely allied to the cochineal insect, Coccus cacti; kermes, C. ilicis and Polish grains, C. polonicus, all of which, like the lac insect, yield a red colouring matter . The minute larval insects fasten in myriads on the young shoots, and, inserting their long proboscides into the bark, draw their nutriment from the sap of the plant . The insects begin at once to exude the resinous secretion over their entire bodies; this forms in effect a cocoon, and, the separate exudations coalescing, a continuous hard resinous layer regularly honeycombed with small cavities is deposited over and around the twig . From this living tomb the female insects, which form the great bulk of the whole, never escape . After their impregnation, which takes place on the liberation of the males, about three months from their first appearance, the females develop into a singular amorphous organism consisting in its main features of a large smooth shining crimson-coloured sac—the ovary—with a beak stuck into the bark, and a few papillary processes projected above the resinous surface . The red fluid in the ovary is the substance which forms the lac dye of commerce . To obtain the largest amount of both resin and dye-stuff it is necessary to gather the twigs with their living inhabitants in or near June and November . Lac encrusting the twigs as gathered is known in commerce as "stick lac"; the resin crushed to small fragments and washed in hot water to free it from colouring matter constitutes " seed lac "; and this, when melted, strained through thick canvas, and spread out into thin layers. is known as " shellac," and is the form in which the resin is usually brought to European markets . Shellac varies in colour from a dark amber to an almost pure black; the palest, known as " orange-lac," is the most valuable; the darker varieties —" liver-coloured," " ruby," " garnet," &c.—diminish in value as the colour deepens .

Shellac may be bleached by dissolving it in a boiling

lye of caustic potash and passing chlorine through the solution till all the resin is precipitated, the product being known as white shellac . Bleached lac takes light delicate shades of colour, and dyed a golden yellow it is much used in the East Indies for working into chain ornaments for the head in sealing-wax, and forms the basis of some of the most valuable varnishes, besides being useful in various cements, &c . Average stick lac contains about 68 % of resin, 10 of lac dye and 6 of a waxy substance . Lac dye is obtained by evaporating the water in which stick lac is washed, and comes into commerce in the form of small square cakes . It is in many respects similar to, although not identical with, cochineal .