The cells made by the insect for its eggs adhere to the branches in grains, completely en crusting them, and, in commerce, are either im ported in that form, and called stick-lac,' or the grains are gathered from the branches, their colouring matter extracted, and formed into flat cakes, still preserving the granular appearance, and called 'seed-lac,' or the seed-lac is melted up into masses, and called lump-lac.' Shell-lac is seed-lac further purified by being put in bags of fine linen, and melted over a charcoal fire until it passes through them. The bags are squeezed, and passed over a smooth surface of wood, on which the lac is deposited in thin layers. 1 f pure, this kind of lac will take fire on a hot iron, and burn with a powerful smell. The heat of a ship's hold will sometimes run it into a solid mass, and thus diminish its value. By pouring warm water on stick-lac, a crimson colouring matter is obtained, which is made into square cakes for sale, and called lac dye, lac lake, or cake lake. These cakes, when broken, aro dark coloured, shining, and compact, but when scraped they yield a bright red powder approaching ennui ne.
The best quality of stick-lac is obtained from Siam, tho.twigs being frequently encrusted all round to the depth of a quarter of an inch, while sometimes a great accumulation takes place on one spot ; that of Assam ranks next; the stick lac of Bengal is inferior to these, being scanty and irregular in its coating of resinous matter.
The largest export is from the Central Provinces, but it is also produced in considerable quantity in Assam, and in the Gaya and dis tricts, in Oudh, the North-Western Provinces, the Panjab, and a limited portion of Sind, in Maisur, and in British Burma. The lao which is so largely exported from Burma is obtained chiefly in the Shan districts, and is perhaps the finest in the world, preferable even to that of Bengal. The jungle at Taldung-ali consists chiefly of thorny bushes, jujube of two species, an Acacia and Butea frondosa, the twigs of the latter often covered with lurid red tears of lac, which is there collected in abundance.
The supply of lao from among the mountains of India could support a consumption ten times greater than at present. In Cuttack, Travancore, Mysore, and most of the Madras districts, it is found in considerable abundance.
Previous to the discovery of the true cochineal, the colouring matter of the lac insect was uni versally employed for dyeing red. The crimsons of Greece and Rome, and the imperishable reds of the Brussels and Flemish schools, were obtained from this source.
A mixture of lac, alum, and tamarind-water is the native dye for silk or cotton cloth of a crimson colour.
After the dye is extracted, the gum-lac still requires much purification before it can be used for the more delicate varnishes. A premitun of 30 guineas and a gold medal were offered by the Society of Arts for a varnish made from shell or seed lac, equally hard, and as fit for use in the arts, as that prepared from any other sub stance. These were claimed by two persons, Mr. Field and Mr. Liming, and as both their processes were found to answer the desired end, a premium of 20 guineas was awarded to each.
The chief consumption of lac in Europe is for the manufacture of sealing-wax and varnishes. In India the inferior kind is made into bangles or armlets for women of the lower classes, the superior is fashioned into rings, beads, and other trinkets. To fit it for such purposes, the natives purify it by melting in bags. When the lac begins to exude, it is scraped off, and the bags are twisted or wrung by means of cross sticks at their ends, to force out the melted contents.
The natives of India make a good varnish of lac, coloured with cinnabar or some other pigment, with which they varnish boxes, cabinets, and other articles. Coloured varnishes of this description are much used in theadornment of their religious houses.
Lac and sandarach form the basis of spirit varnishes ; these resins are more soluble than amber, anime, and copal. They are dissolved in spirits of wine, or pyroligneons spirit, which is cheaper. Lac is harder than sandarach, and is the basis of most lacquers, and also of French polish. Sandarach is used for making a pale varnish for light-coloured woods. It may be hardened by the addition of shell-lac or of mastic if required to be kept pale; and when required to be polished, Venice turpentine is added to give it body.
Tho Indian lapidaries make use of lac as a vehicle for retaining the hard corundum powders used in cutting and polishing gains, and as laps.
Lac enters into the composition of the best Chinese lacquer,—gamboge or dragon's blood, with copal, being added to increase the colour.
Tho exports of lac, of kinds, from India have been as under :— The name lac or lakaha is derived from the word signifying a hundred thousand, from the great number of the insects which swarm over the tree.
It is the female insect of the Coccus lacca that produces the resin and the dye. This is a small, round, red-coloured, flat insect, having 12 abdo minal kings, and a bifurcated tail. The male is much larger than the female, and is furnished with wings. It is stated that no more than about one male to 5000 females is to be met with. The female insect is said to be destroyed in the process of producing her young ones, for the eggs become hatched beneath the mother insect within the concrete resin globule, and escape by boring through the mother's back. At first, the young brood, having made its escape, clusters on the twigs of the trees, and very shortly afterwards the incrustation of lac begins to be formed over and round them, covering the twigs. The bubble like exudations are all close together, and hollow and cellular inside. About the end of March the lac-resin exudation is complete, and the female insects within are glued down by it to the tree. The oval body of the insect becomes of a deep-red colour. If at this stage a little piece of the lac incrustation on a twig be broken off, the insect is perceived as a little bag of red liquid (which yields the dye), and the place where the wood of the twig has been punctured bears a snow-white mark, as if the place had been touched with a point of chalk. On removing an entire piece of lac incrustation from the twig, the bark underneath is observed to be covered with these little white dots, one in every cell and one under every in sect ; under the microscope they clearly appear to be specks of a semi-crystalline saline efflorescence at the place punctured by the insect.
The proper stage to collect the lac (if intended to produce dye) is when the insect is in the stage of being like a soft red sac. At a later stage it lays its eggs under its body, which is glued down by the resin ; when, therefore, the eggs are hatched, they have no means of egress save by eating through the body of the mother, which they do, feeding the while on the red colouring matter contained in her body, which is thus con sumed.
When the lac is first gathered, it is picked off the twigs with the insects and all on it. In this state it is called kacha' or kham lakh.' This lac is treated with water, and thus the colouring matter is extracted. The clarified kind of lac is called chapra-lakh,' or shell-lac, chapra, a shell.