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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![acid. The solution thus obtained can then be tested further; for this purpose it is evaporated almost to dryness, a few drops of water are added, and then a drop of solution of ferrocyanide of potassium. 12. If a mixture of a compound of copper with carbonate of soda is exposed on a charcoal support to the inner jBLame of the blowpipe, metallic copper is obtained, without incrustation of the charcoal. The reduction may be also very conveniently effected in the stick of charcoal (p. 24). The best method of freeing the copper from the pai-ticles of charcoal is to triturate the fused mass in a small mortar with water, and to wash off the charcoal powder, when the copper-red metallic particles will be left behind. 13. If copper, or some alloy containing copper, or a trace of a salt of copper, or even simply the loop of a platinum wire dipped in a highly dilute copper solution, is introduced into the fusing zone of the gas flame, or exposed to the inner blowpipe flame, the upper or outer portion of the flame shows a magnificent emerald-green tint. Addition of hydrochloric acid to the sample considerably heightens the beauty and delicacy of this reaction. The flame is then of an azure-blue colour. 14. Borax readily dissolves oxide of copper in the outer gas- or blowpipe-flame. The beads are green while hot, blue when cold. In the inner flame, the bead is colourless unless a very large quantity of copper is present; when cold it is red and opaque. In the lower re- ducing zone of the Bunsen gas flame, the bead does not become reddish- brown until the addition of binoxide of tin, when this change rapidly takes place, owing to the production of cuprous oxide. If the bead is introduced alternately into the lower oxidizing zone and the lower reducing zone, it becomes ruby red and transparent. §121. c. Oxide of Bismuth, BiO, [BiAl- 1. Bismuth is of a reddish-white colour and moderate metalKc lustre; it is of medium hardness, brittle, and melts at 264°; it does not change in air at the ordinary temperature, but if fused upon charcoal it forms an incrustation of yellow oxide. It dissolves readily in nitric acid, but is nearly insoluble in hydrochloric acid and altogether so in dUute siilphuric acid. Concentrated sulphuric acid converts it into sulphate of oxide of bismuth, with evolution of sulphurous acid. 2. Oxide of bismuth is a yellow powder, which transiently acquires a deeper tint when heated. It fuses at a red heat. Hydrate of oxide of bismuth is white. Both the oxide and its hydrate dissolve readily in hydrochloric, sulphuric, and nitric acids : fused with cyanide of potassium, they yield metalKc bismuth. The grayish-black suboxide of bismuth, BiO^ [BiO], and the red bismuthic acid, BiO^ [BLOJ, are converted into teroxide by ignition in the air. By heating with nitric acid, they are converted-into nitrate of oxide of bismuth. 3. The salts of oxide of bismuth are not volatile; most of them are decomposed at a red heat. Chloride of bismuth is volatile. The salts of oxide of bismuth are colourless or white; some are soluble in water, others insoluble. The normal soluble salts redden litmus- paper ; they are decomposed by a large quantity of water into insoluble](https://iiif.wellcomecollection.org/image/b21966953_0172.jp2/full/800%2C/0/default.jpg)
