Qualitative chemical analysis / by C. Remigius Fresenius.

Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: Qualitative chemical analysis / by C. Remigius Fresenius. 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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    mercurous sulphide (HggS), whicli is insoluble in dilute acids, sulphide of ammonium, and cyanide of potassium. Sulphide of sodium (NagS) in presence of caustic soda, dissolves this precipitate with separation of metallic mercury; sulphide of sodium containing excess of sulphur dissolves it without sepa- ration of metallic mercury; the solutions contain mercuric sulphide. When boiled with concentrated nitric acid, mer- curous sulphide gives up part of its mercury, and a white compound [Hg(N03)2+ 2HgS] is formed. Mercurous sul- phide is readily dissolved by aqua regia. 5. Sulphide of ammonium produces the same precipitate. 6. Potash produces a black precipitate of mercurous oxide (HggO), insoluble in excess of the precipitant. 7. Ammonia produces a black precipitate of a complicated composition, insoluble in excess of the precipitant. 8. If a drop of a mercurous solution is put on a clean plate of copperf and washed off after some time, a spot will be produced which, on being gently rubbed, will appear bright and shining like silver. The application of a gentle heat to the copper causes the mercury to volatilize, and thus removes the silvering. 9. Stannous chloride produces a grey precipitate of metallic mercury. By decanting the supernatant fluid and boiling the deposit with hydrochloric acid, distinct globules will be obtained. Ziead« DRY REACTION. 1. Mixed with carbonate of ^ sodium, and heated on charcoal before the blowpipe, compounds of lead give mal- leable metallic globules. WET REACTIONS. 2. Hydrochloric acid produces in somewhat strong solu- tions a heavy white precipitate of chloride of lead (PbClg), soluble in a large amount of water, especially when heated. The chloride of lead is converted by ammonia into a basic salt (PbClg. 3PbO -h HgO), also a white powder, but almost abso- lutely insoluble in water. In dilute nitric and hydrochloric acids, chloride of lead is more difficultly soluble than in water. 3. Hydrosulphuric acid produces a black precipitate of
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