Introduction to the study of organic chemistry : the chemistry of carbon and its compounds / by Henry E. Armstrong.

  • Armstrong, Henry Edward, 1848-1937.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Introduction to the study of organic chemistry : the chemistry of carbon and its compounds / by Henry E. Armstrong. Source: Wellcome Collection.

    29/382 (page 11)
    in organic bodies by the ordinary tests, but only after destroying the compound by ignition with an alkali or a metallic oxide, or by heating with concentrated nitric acid. A variety of methods for determining these elements have been proposed, but one of the simplest is that devised by Carius. A weighed quantity of the substance ('a-^ grm.) is intro- duced, together with about 5 grms. of nitric acid (Sp. gr. i’5)— and if the substance contain chlorine, bromine, or iodine, a few crj'Stals of argentic nitrate—into a piece of combustion tube 15-18 inches long, securely sealed at one end. The open end is next drawn out to a point, and sealed, and the tube is then heated in an oil-bath for 2-4 hoars, at a temperature of 150°- 300°, according to the nature of the substance. When cool, the point of the tube is carefully opened in the blow-pipe flame, the gas is allowed to escape, the top of the tube is cut off, and the contents washed into a beaker. Supposing the substance to have contained chlorine, bromine, or iodine and sulphur, or phosphorus, the argentic chloride, bromide, or iodide, is filtered off and weighed ; the excess of silver in solution is precipitated by hydrochloric acid, the precipitate is removed by filtration, and the sulphur or phosphorus, present in the filtrate as sul- phuric or phosphoric acid, may then be determined in the usual manner by precipitation as baric sulphate, or ammonic magnesic phosphate respectively. Chlorine (bromine or iodine) may also be estimated by heating the substance to redness in a tube with pure quick- lime, whereby calcic chloride (bromide, iodide) is fonned. The contents of the tube are afterwards dissolved in dilute nitric acid, and the chlorine (bromine or iodine) preci])i- tated as argentic chloride (bromide or iodide). Again, sulphur and phosphorus may be determined by fusing the organic substance with pure sodic hydrate and potassic nitrate, or by heating in a tube with sodic carbonate, or potassic chlorate. In all these cases a sulphate, or phos- phate, is formed by the oxidation of the sulphur, or phos- phorus, which is then estimated in the usual manner.