_Kali Sulphuretum_, P.L. 1787. _Hepar Sulphuris._
QUALITIES. _Form_, a hard brittle mass; _Colour_, liver brown, hence the
old name of _hepar_; _Taste_, acrid and bitter; _Odour_, none when dry,
but if moistened, it yields the stench of sulphuretted hydrogen.
CHEMICAL COMPOSITION. I consider this substance as a mixture of Sulphate
of Potass, with variable quantities of Sulphuret and Bi-Sulphuret of
Potassium.[612] INCOMPATIBLE SUBSTANCES. It is instantly decomposed by
water, the oxygen of which forms Potass with the Potassium; while its
hydrogen, combining with the sulphur, produces Sulphuretted hydrogen,
part of which escapes, and another part forms, with the excess of
Sulphur, Bi-Sulphuretted hydrogen; this latter body uniting with the
base, produces what has been termed an _Hydroguretted Sulphuret_, but
which might be more properly called an _Hydro-bi-Sulphuret_; upon adding
an acid to the solution, a quantity of Sulphur is thrown down,
Sulphuretted hydrogen is evolved, and a salt of Potass remains in
solution. Metallic salts also decompose it, the metal falling down as a
Sulphuret, or Hydro-sulphuret. MEDICINAL USES. It presents us with a
form in which sulphur is soluble in water; it is diaphoretic, and has
been found advantageous in cutaneous affections, (_Form. 118_,) and in
arthritic and rheumatic complaints; while, from its known chemical
action on metallic salts, it has been proposed as an antidote to such
poisons. Its solution has been lately recommended as a lotion for the
itch of infants, and in some cases it has been known to succeed after
the sulphur ointment had failed.[613]