Page:The American Cyclopædia (1879) Volume X.djvu/82

76 LAO eggs. Upon the outside the concrete resinous lumps are marked with numerous pores as if perforated with a needle; within are seen many oblong cells, which often contain dead insects. The substance is of a deep reddish brown, of shining fracture, astringent, and bitterish. It colors the saliva red, and pro- duces a dye of this color but little inferior to the real cochineal. Indeed, before the discovery of the latter it was the material of the fine rich crimson dye of the ancients, and of the durable reds of the dyers of Brussels and Holland. The coloring matter is readily extracted by warm water ; the lac itself is for the most part solu- ble in alcohol, also in an aqueous solution of borax, by which it may be distinguished from most common resins with which it is some- times adulterated ; when burned it diffuses a strong agreeable odor. The crude article broken off with the twigs is known as stick lac, and is sold by those who gather it at from 2 to 4 Ibs. for a penny. When the stick lac is broken up and its coloring matter is partially removed by water, it is called from its granular appearance seed lac. This is sometimes melted^into masses and called lump lac. The more familiar va- riety known as shell lac is prepared by melting the" seed lac and straining it through fine linen bags, upon a flat, smooth surface of wood, to harden. It dries in thin sheets, which break up into small fragments. Their color is from orange to dark reddish brown ; they are more or less transparent, hard, brittle, and shining. The substance is soluble in alcohol, but not in water, and possesses neither taste nor smell. It softens readily by heat, so that it has run together in masses when stowed in the hold of a ship. It contains, as found by Hatchett, 90'9 per cent, of resin and 0*5 of coloring matter ; the remainder is wax, gluten, and foreign mat- ter. Stick lac contains about 10 per cent, of coloring matter and 68 per cent, of resin. The coloring matter is separated by treatment with warm water and evaporation, and, made into square cakes, is known as lac dye, lac lake, or cake lake. When scraped they yield a bright red powder like carmine. A varnish and pig- ment combined is prepared from stick lac for the process of japanning. The natives of India employ the substance in various ways. They color it with yellow orpiment and make it into bracelets, chains, and other ornaments in imi- tation of gold. They prepare with it a good varnish, which they color with cinnabar or some other pigment. The wheels of their lap- idaries are covered with a preparation of lac, which by its adhesive nature retains the pol- ishing powders. The chief uses of shell lac are for manufacturing sealing wax, and as the basis for spirit varnishes and the French polish. The best red sealing wax contains 48 parts in 100 of it, together with 19 parts of Venice turpen- tine, 1 of balsam of Peru, and 32 of finely pow- dered cinnabar. It forms 60 per cent, of the best black sealing wax, the other ingredients being 10 parts of turpentine and 30 of levigated LACANDONES bone black. The coloring matter and some insoluble ingredients, which are never wholly removed from shell lac, injure it for a varnish for light-colored works; but recent methods of bleaching, one of which by chlorine was introduced by Dr. Hare, have in a great mea- sure removed this difficulty. (See VAKNISH.) The adhesive quality of lac adapts it for ce- ments for broken porcelain, and united with caoutchouc it makes the famous marine glue. A weak solution of it in alcohol is recommended in surgery to be spread on bandages for dress- ing wounds and ulcers. Formerly it was used in medicine, but it has no specific action. The best stick lac is brought from Siam, and next to this ranks that from Assam. In the best articles the sticks are frequently incrusted en- tirely around with the lac to the thickness of a quarter of an inch ; and the substance also forms large oblong bunches of much greater thickness. The Bengal stick lac is commonly in very scanty and irregular incrustations. The capacity of production is said to be many times greater than the demand, though the annual exportations amount to several million pounds of lac dye and shell lac. LA CAILLE, Mcolas Lonis de, a French as- tronomer, born at Rumigny, near Rheims, March 15, 1713, died in Paris, March 21, 1762. He was a pupil of Cassini in the observatory of Paris, assisted Maraldi in the survey of the coast between Nantes and Bayonne, and after- ward (1739-'40) took part in the measurement of the arc of the meridian, correcting the results of Picard, and proving the flattening of the earth toward the poles. Being appointed pro- fessor of mathematics in the Mazarin college, he published (1741-'50) lectures on mathema- tics, mechanics, astronomy, and optics, which have passed through many editions. He next devoted himself to astronomical observations, both at his observatory and at the Cape of Good Hope. His catalogue of stars made at the lat- ter station excited especial surprise from the quickness and accuracy of its formation. By simultaneous observations made by himself at the Cape and by Lalande at Berlin, he estab- lished the distance of the moon and of the planets Mars and Yenus. While there he re- ceived orders to survey the island of Bourbon and the isle of France (Mauritius). On his return he investigated anew the problem of finding the longitude at sea, and proposed the modern plan of a nautical almanac. In 1757 he published his Astronomic^ Fundamenta ; in 1758, Tables solaires ; and soon after, Bou- guer's treatise De la gradation de la lumiere, and a new edition of the Nouveau traite de navigation by the same author. After his death his friend Maraldi published his treatise on the "Southern Starry Heavens," and his " Voyage to the Cape." La Caille was the au- thor of a large number of other treatises, chief- ly on astronomical subjects. LACANDOXES, an Indian tribe of Central America, whose territory, formerly embracing