Qualitative analysis / by William Briggs and R.W. Stewart.

  • William Briggs
Date:
1913
Catalogue details

Licence: Public Domain Mark

Credit: Qualitative analysis / by William Briggs and R.W. Stewart. Source: Wellcome Collection.

    94/180 (page 78)
    7. In neutral solutions of formates, ferric chloride gives a red coloration, but no precipitate in the cold. To a portion of this red solution, add a little hydrochloric acid, when the colour will be destroyed. If the rest of the solution is boiled, a reddish precipitate of a basic iron salt will be produced. ACETIC ACID. H4C202 or CH3. COOII. Acetic acid is a pungent-smelling, strongly-acid liquid. When anhydrous, it is known as “ glacial acetic acid.” It solidifies in the cold, forming large crystalline plates, which melt at 17°, and boil at 118°. It attacks the skin, and its vapour burns with a pale blue flame. With water, alcohol, and ether, it is miscible in all proportions, and it is largely used as a solvent in organic chemistry. All neutral acetates are soluble in water, and on ignition in the dry state yield inflammable vapours, consisting chiefly of acetone. 2 CH3 . COONa = CII3. CO . CH3 + Na2C03. Acetone 1. On heating an acetate with strong sulphuric acid, acetic acid is set free, and can be recognized by its smell (cf. formic acid). 2 CHS. COONa + H2S04 = 2 CH3. C00H + Na2S04. 2. When a mixture of equal parts of arsenious oxide and an acetate is heated, the intensely obnoxious and highly characteristic smell of cacodyl oxide is noticed. As406 + 8 CH3. COOK = 2 As2(CH3)40 + 4 K2COs + 4 C02. Cacodyl oxide This is one of the best tests for the presence of an acetate, but only small quantities of the substances should be used. As the liquid (cacodyl oxide) is exceedingly poisonous, the experiment should be performed in a fume cupboard, and care should be taken not to inhale the fumes.