5. (Wöhler.) Nitrate of potassa, 1 part, is mixed, in alternate layers, with clippings of sheet copper, 2 or 3 parts, and then heated to moderate redness for about 1⁄2 an hour in a copper or iron crucible; when cold, the potassa is washed out with distilled water, and the solution, after repose in a closed vessel, decanted as before. Not a trace of copper can be detected in the liquid. The clippings may be again used if mixed with a little fresh metallic copper.
6. (Wholesale.) From carbonate of potash (kali), 1 lb., and quicklime, 1⁄2 lb., to each gall. of water.
7. (Brandish’s alkaline solution; Liquor potassæ Brandishii.) From American pearlashes, 6 lbs.; quicklime and wood ashes (from the ash), of each 2 lbs.; boiling water, 6 galls. (old meas.); to each gall. of the clear product is added 12 or 15 drops of oil of juniper. This ‘solution’ is much asked for in trade. Ordinary liquor of potassa is generally sold for it.
Pur. “Nothing, or scarcely anything, is
thrown down from this solution on the addition of lime water; and when it has been first saturated by nitric acid, no precipitate falls on the addition of carbonate of soda, chloride of barium, or nitrate of silver. What is thrown down by bichloride of platinum is yellowish.” (Ph. L.)
Uses, &c. Liquor of potassa is antacid, diuretic, resolvent, and lithontriptic.—Dose, 10 to 30 or 40 drops, in any bland diluent (not acidulous); in heartburn, gout, calculi, indurations, scrofula, lepra, psoriasis, &c.
Obs. Quicklime fails to abstract the carbonic acid from the alkaline carbonates in solutions much stronger than those above referred to. Weaker solutions may, however, be easily concentrated by evaporation in iron vessels. See Potassium, Hydrate of, and below.
Solution of Potas′sa (Effervescing). Syn. Liquor potassæ effervescens (B. P.); Effervescing potash water, Supercarbonate of potassa w.; Aqua potassæ effervescens (Ph. E.), A. p. supercarbonatis, L. Prep. (Ph. L. & E.) Bicarbonate of potash, 1 dr.; distilled water, 1 pint; dissolve, force in carbonic acid gas in excess, and keep it in a well-stoppered bottle. Resembles soda water, but sits better on the stomach. It is almost specific in the early stages of scurvy.
(B. P.) Dissolve 30 gr. of bicarbonate of potash in one pint of distilled water, filter, pass in washed carbonic acid (obtained by the action of sulphuric acid on chalk) up to a pressure of 7 atmospheres. Keep in bottles closely secured.
Obs. An excellent substitute for this preparation is to pour a bottle of soda water into a tumbler containing 20 gr. of powdered bicarbonate of potash, and to drink it immediately.