BORAX, a compound of the metal sodium with boracic acid (q.v.). The formula of boracic acid may be written HBO.± H.0; and if the hydrogen of the HBO, is replaced by sodium, a compound known as sodium borate is formed, which crystallizes as NaBO, 4H2O. Fused borax is this salt deprived of its water of crystallization, and combined with boron trioxide in the form 2NaBO, B.O., or Na,B40,. Common borax, when crystallizing from aqueous solution, however, contains 10 molecules of water. Other forms of borax are easily obtained, crystallizing with different quantities of water. Borax occurs native, both as a saline efflorescence on the soil, and as monoclinic crystals. Until recent times the principal borax supply of the world was ob tained from the salt lakes of Tibet. It was brought to Europe in the crude state, under the name of tincal. Enormous quantities of borax are now obtained from California and Nevada. Borax Lake, some 80 miles north of San Francisco, was discovered in 1856. It contains borax in solution, and crystals of the mineral also occur in the surrounding mud and marshes. The crystals are occasionally quite large, weighing as much as a pound each. It is also found in large quantities at Borax Lake in San Bernardino County, Cal., and it occurs abundantly as an efflorescence in Death Valley, Inyo County, Cal. Borax bearing clays are found in the beds of many extinct lakes of arid Western United States. They are believed to be residues from the evaporation of borax lakes. At other points borax is believed to be precipitated from hot gaseous volcanic emana tions. The chief refining plants for borax are at Alameda and Searles.> Cal, and in New Jersey. The crude material is dissolved in water and heated in conjunction with sodium carbonate. This solution is next placed in cool ing tanks in which are suspended steel rods, on which the borax forms. For added degrees of purity successive crystallizations are em ployed until the desired degree is reached, Different methods of refining are employed in various countries on the form of the crude material. Borax is extensively used
in the household, and it is used also as an antiseptic and preservative. Like boracic acid, it is employed in glazing porcelain and in mak ing enamels. Its property of dissolving metallic oxides makes it of great value in blowpipe analysis (q.v.) and as a flux in the soldering of metals. In the United States commercial borax is chiefly derived from the colemanite deposits of California. About 55,000 tons valued at $1,600,000 are produced annually in California. Chile is the second largest pro ducer of borax, the ore being a sodium cal cium borate.
Borax is of toxicological interest because it is widely used as an antiseptic, a preservative for meats and other foodstuffs, and also as an abortifacient. In large doses there is marked gastro-enteritis, in addition to which there are symptom's of collapse, coldness of the skin, bad pulse, psychical depression and diminution in the quantity of urine eliminated. Similar symp toms may occur from the use of borax in washing out large abscess cavities. Singultus and general motor paralysis are the symptoms in fatal cases. Borax certainly has a toxic action on the kidneys when taken in large amounts. There is albumen in the urine, casts, pain in urination, and even bloody urine. While the kidneys are markedly affected by, large doses it is questionable whether borax, in the small amounts used in food preservation, causes any grave symptoms of kidney irritation, even when taken for a considerable length of time. It may well be that certain individuals have an idiosyncrasy to boron salts, in which case their use would prove detrimental. Con sult 'Mineral Resources of the United States> (Washington, annually) and (Annual Bulletin No. 24, California State Mining Bureau.' See BORGAN ; MINERAL PRODUCTIONS OF THE UNITED STATES.