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To Obtain Oxalic Acid

Liebig proposes: Nitric acid (specific gravity 1.42), 5 parts; water, 10 parts; mix, add sugar, or preferably potato starch, 1 part, and by precipitating a solution of binoxalate of potash with acetate of lead, washing the precipitate with water, and decomposing it, while phuretted hydrogen. Filter and evaporate still moist, with dilute sulphuric acid or sulgently , so that crystals may form as it cools. from Epsom Salts. Oxalic acid has occa- 3904. To Distinguish Oxalic Acid digest by a gentle heat as long as gaseous sionally been mistaken for Epsom salts, with products are evolved; evaporate and crystal- fatal results. They may be easily distinguishlize, dry the crystals, redissolve in the smalled. Epsom salts taste extremely bitter and est possible quantity of boiling water, and nauseous; oxalic acid tastes extremely sour. crystallize; 12 parts of potato starch yield It is safer to taste a weak solution in apply- 5 of acid. The mother water, treated with ing this test. Epsom salts, dissolved in water more nitric acid, and again warmed, will and mixed with carbonate of soda, or carboyield a second crop of crystals; and this nate of potash, turn milky, and, after a time, a should be repeated till the solution is exhausted. should be repeated till the solution is exwhite sediment subsides; oxalic acid, mixed effervesces, and the liquid, in a few seconds, with carbonate of soda or carbonate of potash, becomes transparent. acid forms small, feathery, and nearly color-