ETHION′IC AC′ID

Prep. An alcoholic solution of the crystals of sulphate of carbyle is diluted with water, the whole neutralised with carbonate of baryta, the filtered liquid evaporated by a very gentle heat to a small bulk, and a large quantity of alcohol added; the precipitate (ethion ate of baryta) is treated (cautiously) with dilute sulphuric acid (avoiding exce ), by which the baryta is withdrawn, and ethionic acid left in solution. Prop., . Ethionic acid closely resembles sulphovinic acid. It is decomposed by heat. Its salts (ethion ates), however, differ completely from the sulphovinates. They are all soluble in water, and are said to be anhydrous. The ethion ates of ammonia, pota a, and soda crystallise readily; those of lead, baryta, lime, and the other earths are uncrystallisable. See Is eth ionic Acid , and below .