3891. To Obtain Pure Glacial or Hydrated Acetic Acid

3891.     To Obtain Pure Glacial or Hydrated Acetic Acid. Place 30 parts dry and finely powdered pure acetate of soda in a capacious retort, and pour on it 97 parts pure sulphuric acid. The heat developed by the action of the ingredients will cause one-eighth of the acetic acid to pass over. The retort may then be placed in a sand bath until the contents become quite liquid. The product, carefully rectified, yields 2 parts of pure acid containing only 20 per cent, of water. By exposing the latter portion, which comes over in a closed vessel, to a temperature below 40° Fahr., crystals of hydrated (glacial) acetic acid will be deposited. The liquid portion being then poured off, the crystals are again melted and re-crystallized by cooling. These last crystals, separated from the liquid, are perfectly pure.

3892. To Obtain Glacial or Hydrated Acetic Acid Without Distillation

3892.    To Obtain Glacial or Hydrated Acetic Acid Without Distillation. The acid may also be obtained without resorting to distillation, thus: Place 100 parts powdered acetate of soda (pure commercial) in a hard-glazed stoneware or glass pan; pour 35 or 36 parts concentrated sulphuric acid gradually into the pan, so that the acid may flow under the powder, and as little heat as possible be generated by the operation. In furtherance of this necessary end, the process is best conducted in a cool apartment, and the pan kept well cooled. The whole must now be covered and allowed to stand for some hours, when crystalline grains of sulphate of soda will be found covering the inside of the vessel, and hydrated acetic acid, partly liquid and partly in crystals, in the upper portion. The temperature must then be raised just sufficiently to liquefy the crystals of acetic acid, the fluid poured off, and a very small quantity of pure acetate of lime added gradually, until it yields no trace of sulphuric acid on evaporation. After repose it may be decanted for use.

3893. To Obtain Pure Acetic Acid

3893.    To Obtain Pure Acetic Acid. Triturate together 10 parts crystallized neutral acetate of lead, and 3 parts effloresced (dry) sulphate of soda; mix together 21/2 parts each of sulphuric acid and water, and, when cold, pour it on the acetate and sulphate, previously placed in a retort; then distill to dryness in a sand bath. The acid that comes over in the distillation by this process is very pure, and may be used as a test acid for chemical analyses.

3894. To Obtain Anhydrous Acetic Acid

3894. To Obtain Anhydrous Acetic Acid. This is acetic acid free from water, as it exists in dry acetates. Mix, in a glass retort, well-fused acetate of potassa with half its weight of chloride of benzoyle; apply a gentle heat, collect the liquid that distills over, and rectify it carefully. Hot water added to this resolves it into hydrated or glacial acetic acid.