Present name. - Potassic Permanganate. KMnO4.
This may be procured from the operative chemists.
Characters and Tests. - Dark purple, slender, prismatic crystals, inodorous, with a sweet astringent taste, soluble in water. A single small crystal suffices to form with 1 ounce of water a rich purple solution, which, when mixed with a little rectified spirit and heated, becomes yellowish-brown. The crystals heated to redness decrepitate, evolve oxygen gas, and leave a black residue, from which water extracts Potash, recognized by its alkaline reaction, and by its giving, when acidulated with Hydrochloric Acid, a yellow precipitate with Perchloride of Platinum. Entirely soluble in cold water. 5 grains dissolved in water require for complete decolouration a solution of 44 grains of granulated Sulphate of Iron acidulated with 2 fluid drachms of diluted Sulphuric Acid.
Reference to Horn. Proving. - Brit. Journ. of Horn., vol. xxv.
Preparation. - Solution in distilled water, which must be freshly made.