Manual of qualitative analysis / by Robert Galloway.

  • Galloway, Robert.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: Manual of qualitative analysis / by Robert Galloway. Source: Wellcome Collection.

    244/272 (page 226)
    will be precipitated as sulphides; the precipitate must be well washed, and then boiled with dilute sulphuric acid. The sulphide of cadmium is decomposed by the sulphuric acid, sulphate of cadmium being formed, which dissolves— whilst the sulphide copper is undecomposed and undis- solved. Separate the two by filtration; test the filtrate for cadmium by sulphuretted hydrogen ; dissolve the sul- phide of copper in nitrie acid; neutralize with ammonia, acidify with acetic acid, then add ferrocyanide of potassium. This is a good method: the only precaution to be attended to is, that the mixed sulphide must be washed rapidly, so that the sulphide copper may not become oxidized by expo- sure to the air. c. “The blowpipe experiments that require the assistance of charcoal may be divided into two classes. In the first class may be named the formation of beads with microcosmic salt, the trial of fusibility per se, and the roasting of the metallic compounds that contain such volatile elements as sulphur and arsenic. The second class of experiments is restricted to the fusion of minerals or metallic compounds with carbonate of soda, or with soda and borax, for the purpose of effecting particular combinations, or of procuring their metals in a state of regulus. For these two classes of experiments I make use of two different composition supports, the first of which I call Supports for Fusions, and the second, Supports for Reductions. They are alike in appear- ance. ach consists of two parts—an upper or combustible portion, and a base or incombustible portion. The former is the proper substitute for the ordinary charcoal, the under portion acting only as a crucible in which the combustible portion is contained. I shall first describe the composition and formation of the supports, and afterwards show the way to use them,