_Borax._
QUALITIES. _Form_, irregular hexahedral prisms, slightly efflorescent.
_Taste_, alkaline and styptic; when heated it loses its water of
crystallization, and becomes a porous friable mass (_calcined borax_).
CHEMICAL COMPOSITION. Boracic acid, 34—soda, 17—water, 49. SOLUBILITY.
It is soluble in 20 parts of water at 60°, and in 6 parts at 212°.
INCOMPATIBLE SUBSTANCES. It is decomposed by _acids_; _potass_; by the
_sulphates_ and _muriates_ of the _earths_, and by those of _ammonia_.
MEDICINAL USES. It is only applied in the form of powder mixed with 8 or
10 parts of honey, as a detergent linctus in aphthæ, &c. The Chinese
employ it in inflammatory sore throats; for which purpose they first
reduce it to an extremely fine powder, and then blow it through a reed
upon the inflamed surface. OFFICINAL PREPARATIONS. _Mel Boracis_. L.
ADULTERATIONS. _Alum_, and _fused muriate of soda_, are substances with
which it is sometimes sophisticated; to discover which, dissolve it in
distilled water, and after saturating the excess of the base with nitric
acid, assay the solution with nitrate of barytes and nitrate of silver.