_Aqua kali puri._ P.L. 1787. _Lixivium Saponarium_, 1745.
QUALITIES. A limpid, dense, colourless solution; a pint should weigh
℥xvj; when rubbed between the fingers it feels soapy, in consequence of
a partial solution of the cuticle. The solution, as usually prepared,
contains small portions of muriate and sulphate of potass, silica and
lime; but these incidental impurities do not invalidate its virtues; it
ought not to effervesce with acids. MED. USES. Antacid, diuretic,
alterative, and lithonthryptic; and externally, when diluted, it acts as
a stimulating lotion,[557] and if concentrated, as a caustic; see
_Potassa Fusa_. The operation of this and other alkaline remedies, have
at different periods been celebrated as powerful lithonthriptics, and
whilst experience has in some cases confirmed the value of the practice,
it has in others proved no less decidedly its mischievous agency; these
contradictory results are at length capable of explanation, for
Chemistry has drawn aside the veil that has so long obscured the
history, origin, and cure of calculous diseases, and has demonstrated
that these extraneous bodies vary in composition, and are consequently
very differently affected by the same chemical solvents; but this
subject has already been so fully discussed in the first part of this
work, under the chapter on “_Antilithics_ and _Lithonthryptics_,” that
it is unnecessary to dwell upon it in this place.
It has also been found highly useful in the cure of several species of
cutaneous affections; as in Lepra, Psoriasis, &c. which diseases
generally appear to have some connection with a morbid state of the
digestive functions; see _Form: 149_. DOSE of the solution of potass,
♏︎x to fʒss, in veal broth[558] or table beer; this latter vehicle
disguises its nauseous flavour completely. In many cases, the infusion
of some bitter tonic will be the most eligible liquor in which it can be
exhibited, especially where our object is to promote its absorption: the
theory of such a combination has been already explained in the first
part of this work, p. 153. OFFICINAL PREP. _Potassa fusa_, L.E.D.
_Potassa cum calce_, L.E.D. _Liquor Sulphureti Kali_, D. _Antimonii
Sulphuretum Præcipitatum_, L.E.