Present name. - Potassic Hydrate. Kho.
The Liquor Potassae of the British Pharmacopoeia, which contains 27 grains to 1 fluid ounce, has been recommended by Dr. Black as a substitute for Causticum.
Tests. - Specific gravity 1.058. 462.9 grains by weight (1 fluid ounce) require for neutralization 482 grain measures of the volumetric solution of Oxalic Acid, corresponding to 5.84 per cent. by weight of Hydrate of Potash, Kho. It does not effervesce when added to an excess of diluted Hydrochloric Acid. Mixed with an equal volume of distilled water, it gives no precipitate with solution of Lime or Oxalate of Ammonia. When it is treated with an excess of diluted Nitric Acid, and evaporated to dryness, the residue forms with water a nearly clear solution, which may be slightly precipitated by Chloride of Barium and Nitrate of Silver, but is unaffected, or but very slightly affected, by Ammonia.
Preparation. - 2 fluid drachms mixed with 9 fluid drachms of distilled water will form the 1 attenuation, from which the others can be prepared with spirit.