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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![and the salts of bismuth) whereby they are converted into soluble acid and insokible basic compounds. § 21. 2. Alcohol, GJip* [0,H„0]. Preparation.—Two sorts of alcohol are used in chemical analyses, namely, spirit of wine of 0-83 or 0-84 sp. gr. = 91 to 88 per cent, by volume {spiritus rectificatus of the British Pharmacopoeia); and absolute alcohol. The latter may be prepared most conveniently by mixing, in a distilling vessel, 1 part of fused chloride of calcium with 2 parts of rectified spirit of wine of about 90 per cent, by volume, digesting the mixture 2 or 3 days, until the chloride of calcium is dissolved, and then distilling slowly and in fractional portions. So long as the distillate shows a sp. gr. below 0-8037 ( = 98 per cent, by volume), it may pass for absolute alcohol. The portions coming over after that are received in a separate vessel. Tests—Vme alcohol should volatiUze completely, and ought not to leave an odour of fusel oil when allowed to evaporate on the palm of the hand; neither should it alter the colour of moist blue or red litmus paper. When kindled, it must burn with a faint bluish barely percep- tible flame. i t.i • C/ses.—Alcohol is useful (a) for separating substances soluble in_ it from others which do not dissolve—chloride of strontium from chloride of barium for example; {h) to precipitate from aqueous solutions many substances which are insoluble in dilute alcohol, such as gypsum, malate of lime ; (c) to produce various kinds of ether—acetic ether, for example, which is characterized by its peculiar and agreeable smell; (d) to reduce, mostly with the co-operation of an acid, certain peroxides and metallic acids, such as binoxide of lead, chromic acid, &c.; (e) to detect certain substances which impart a characteristic^ tint to its flame, especially boric acid, strontia, potassa, soda, and lithia. § 22. 3. Ether, C^HpLC^H.oO]. 4. Chloroform, 0,HCl3[OHCl3]. 5. Bisulphide of Carbon, CSJCS,]. These solvents find but limited application in the qualitative analysis of inorganic substances; their use indeed is confined almost entirely to the detection and isolation of bromine and iodine. Chloroform and bisulphide of carbon are preferable to ether in this respect. Ether is used for the detection of chromic acid by means of peroxide of hydrogen. As these reagents can be made much better on a large than on a small scale, it is more convenient to purchase them than to make them.^ ^esis.—Ether should be colourless, of sp. gr. of 0-720 to 0-/2o at 17-5°, and require 12 parts of water for solution. The solution must not alter the colour of test papers. Ether must, even at the common * Methylated spirit may be substituted for alcoliol, in almost all analytical operations, if it is used as a solvent merely.](https://iiif.wellcomecollection.org/image/b21966953_0060.jp2/full/800%2C/0/default.jpg)
