Exercises in practical chemistry. Series I : Qualitative exercises / by A.G. Vernon-Harcourt and H.G. Madan.

  • Madan H. G. (Henry George), 1838-
Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: Exercises in practical chemistry. Series I : Qualitative exercises / by A.G. Vernon-Harcourt and H.G. Madan. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    310/394 (page 290)
    A CYANIDE will, if present, have been already detected (13). As a confirmatory test, the reaction with iron protosulphate (Expt. 2, p. 157) may be tried with a fresh portion of the original solution. [A FEBBOCYANiDE will also evolvc cyanogen when heated in a tube, but it may be distinguished from a cyanide by giving a deep blue precipiiaie when the acidified solution is tested with a drop of iron perchloride.] If there is a tinge of yellow in the colour of the precipiiaie, a BBOMiDE is probably present. The reaction with carbon distilphide and solution of clilorine (p. 162) will afford decisive proof. If ihe precipitate is crystalline, and if the original salt blackened when heated in a glass tube (9), an acetate should be tested for, as directed in p. 153, Expt. 3. If none of the above radicles are present, the salt is a CHLOKiDE. If SO, chlorine gas will be evolved when a Httle of the original solution is heated with manganese dioxide and strong hydrogen siilpliate (p. 158, Expt. 3). (C) A light yellow precipitate is formed. The salt is an iodide. The reaction with potassium nitrite and staxch (p. 168) will afford conclusive evidence. (D) A precipitate is formed which is at the first moment white, hut rapidly turns yellow, brown, and finally black. The salt is a hyposulphite. The precipitation of sulphur and evolution of sulphur dioxide, on addition of an acid to the neutral solution, will have been already nodced\ • (E) A black precipitate is produced at once. The salt is a sulphide. The results of the preliminary examination (3 /3) wiU serve to confirm this. presence of a hypophosphite.