A native salt. It is also made artificially by boiling together, in proper proportions, boric acid and carbonate of sodium.

Characters. - In transparent, colourless crystals, sometimes slightly effloresced, with a weak alkaline reaction.

Solubility. - Insoluble in rectified spirit, soluble in water.

Reactions. - A hot saturated solution, when acidulated with any of the mineral acids, lets fall, as it cools, a scaly crystalline deposit (boric acid), the solution of which in spirit burns with a green flame.

Dose. - 5 to 40 grains.

Preparations.

B.P.

Glycerinum Boracis....................

1 part in 6 by weight

(= 1 oz. in 4 fluid oz. glycerine).

Mel Boracis..................

56 grains in 1 oz.

Used also to prepare boric acid.

Uses. - Borax destroys low vegetable organisms and prevents their germination. It thus acts as a disinfectant. Applied to the skin it removes the epidermis, and may be used for this purpose instead of soap. It is used as a lotion in acne. It forms a useful wash to remove scurf from the head, chloasma or liver spots, and to allay itching in urticaria, psoriasis, impetigo, and pruritus pudendi, scroti, and ani; it is also used in acute eczema in a solution of 1 per cent. with 1 per cent. of acetate of alum. In intertrigo it may be dusted on in a mixture with 5 per cent. of oxide of bismuth and starch. It is much employed in aphthous conditions of the mouth and throat, either alone or combined with chlorate of potassium. It may be given simply in solution, or in the form of the honey or glycerine. As an injection it is useful in leucorrhoea and gonorrhoea.

It has been supposed to have a special action upon the uterus, and has been employed in amenorrhoea, dysmenorrhoea, and puerperal fever and convulsions. On account of its asserted power to increase the uterine contraction, it ought either to be avoided or employed with care during pregnancy. Borax is useful in some cases of epilepsy in doses of 10 to 15 grains three times a day. It acts as a solvent to benzoic acid.