The presence of so small a quantity as i% of alcohol may be detected in ether by the colour imparted to it by aniline violet; if water or acetic acid be present, the ether must be shaken with anhydrous potassium carbonate before the application of the test.
When heated with ammonia it yields guanidine, and on boiling with alcoholic potash it yields potassium carbonate.
The salt is obtained from the soil in which it occurs naturally, or from the heaps in which it is formed artificially, by extracting with water, and adding to the solution wood-ashes or potassium carbonate.
A better method is Wohler's, in which the finely powdered mineral is fused with twice its weight of potassium carbonate in a platinum crucible, the melt powdered and treated in a platinum basin with aqueous hydrofluoric acid.
They are obtained by neutralizing the solution of the acid, or by fusing the oxide with potassium carbonate and treating the melt with hydrofluoric acid.
