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
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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.

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    Q (C) The substance is unacted upon. It is pro- T„ „ . bably either gold or platinum ; raid if it is In aqua regia, ■' ' ° yellow, platinum if it is white. It will dissolve in aqua regia, and the solution should be examined as directed in 32. 3. Blowpipe Examination. [This should be begun while the solution of the substance is being made, in order to economise time. If no characteristic results are obtained at once, and if the substance has entered readily into solution, the blowpipe examination may be con- tinued at intervals during the testing of the solution, e. g. while a filtration is going on, or a precipitate is subsiding, and the results will be applicable as confirmatory evidence.] _ Place a small quantity of the substance in a tube of hard glass, sealed at one end (Fig. 13, heated^i^^ube. P- ii)> and heat it at first very gently over the Bunsen's burner, and afterwards before the blow- pipe to a temperature as high as the tube will bear. (A) The substance remains unaltered, evert at a high tempera- ture. Pass on to 16. (B) The substance does not fuse, even when heated to redness, and gives off no gas or vapour, but changes colour, (a) From white to yellow, becoming white on cooling. It is ZINC OXIDE, TIN DIOXIDE, Or BISMUTH TBioxiDE (pro- bably the last, if it fuses at a strong red heat). (/3) From red to black, turning red again on cooling. It is probably ieon peroxide. (C) The substance fuses at a very moderate heat, and possibly gives off water {of crystallisation^. Wipe the inside of the tube perfectly dry with 10. twisted slips of blotting-paper, and when no further moisture is condensed, raise the temperature. (D) The substance volatilises entirely. It is a salt of am- monium, aksenic, antimony, or meecuky ; or possibly hydko- GEN oxalate, or suLPHUB. Observe the character of the sublimate in the tube.