solution of the acid, with the assistance of heat, or from a solution of borax and a soluble salt of the base, by double decomposition. They are all decomposed by the stronger acids.
Tests. The borates may be tested by digesting them in a slight excess of oil of vitriol, evaporating the resulting solution to dryness, powdering the residuum, and dissolving it in alcohol; the resulting solution possesses the property of burning with a green flame if the sample examined was a borate, or contained a notable quantity of one. See Boracic Acid.
BORAX. [Eng., Fr.; Ger., L., B. P.] 2NaBO2.B2O3. Syn. Bibo′′rate of so′da, Bo′′rate of s*, Subbo′′rate of s.†, Gold solder†*, Refined′ tinc′al†*; So′dæ bibo′′ras, S. bo′′ras, L.; Chrysocolle, &c., Fr.; Boraxsaures natron, &c., Ger. Commercial biborate of soda. Borax is obtained either by purifying native borate of soda (TINC′AL, TINC′AR), or by saturating crude boracic acid with the alkali. It is never prepared on the small scale unless for chemical analysis.
Prop. Crystals, six-sided prisms, which contain 10 equiv. of water, and effloresce in dry air; soluble in 20 parts of cold, and in 6 parts of boiling water; solution has an alkaline reaction on test-paper; by heat it loses its water of crystallisation, and at a higher temperature fuses to a glass-like substance (see below).
Pur. This may be ascertained by determining the quantity of sulphuric acid required to neutralise a given weight of the sample under examination, as indicated by litmus paper. Common salt and alum are frequently mixed with borax to lower the value. The first may be detected by a solution in hot water giving a curdy-white precipitate with nitrate of silver, soluble in ammonia; the last, by water of ammonia, giving a bulky-white pulverulent precipitate. The former must be distinguished from the white pulverulent precipitate of borate of silver, which is thrown down from pure borax.
Uses, &c. Borax is extensively employed as a flux for metals, for soldering, and in medicine. Internally it is diuretic, sedative, emmenagogue, and refrigerant, in doses of 15 to 40 gr.; externally, made into a gargle for sore throat, and in powder as a detergent in aphthæ, and ulcerations of the month. Dissolved in rose-water, it is used as a cosmetic; and mixed with about 8 times its weight of lard, forms a useful ointment in piles and sore nipples.
The ‘Comptes Rendus’ (lxxx, 473) contains the results of some experiments made by M. Schnetzler, with the view of testing the antifermentative and anti-putrefactive properties of borax.
When the leaves of the Elodea Canadensis were plunged into a concentrated solution of borax, the living matter of the cell was killed, and the same result followed with the fresh leaves and spores of the Vaucheria clavata, the spores of the grape fungus (Oidium sacchari), and of yeast moulds, &c. Infusoria, rotifera, and entomostraca, placed in water containing borax, quickly ceased to move and then died. The larvæ of frogs placed in a solution of borax were killed in less than an hour after immersion. M. Schnetzler thinks the deduction to be drawn from these facts is that borax ought to act antagonistically to fermentation, if this latter be a chemical phenomenon accomplished under the influence of the life of the yeast. To test the correctness of this hypothesis experiments were undertaken with a view of determining the action of borax upon fermentable matters.
Ripe grapes and currants after being kept two years in a concentrated solution of borax, in a closed vessel, presented no trace of fermentation, although, however well preserved, they were not eatable. As a counter test grapes were placed in a well-closed vessel filled with ordinary water, when after a time, according to the temperature, fermentation took place, with evolution of carbonic acid. Thirty cubic centimètres of fresh milk were placed in a test tube with one gram of borax. The cream quickly formed a rather thick layer on the upper portion. Although the test tube was closed by a cork a mould was formed upon the cream, but the remainder of the liquid underwent no acid fermentation, and retained during several months the appearance of very clear creamed milk, and although afterwards under the influence of summer heat the liquid became perfectly limpid, and deposited the casein as a soft white matter, neither the deposit nor the liquid had an acid taste, and after three months they still had the odour of fresh milk. Fresh milk put into a well-closed tube without borax underwent fermentation in two or three days. A piece of sheep’s brain treated with powdered borax, after eight days, although it evolved sulphuretted hydrogen, gave no indications of putrefaction, and after retaining a soft consistence during some months, became hard and almost horny without any disagreeable smell.
A pound of beef was placed in a concentrated solution of borax, in a tin case not hermetically sealed.