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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![§ 29.] CHLOEINE AND CHLORINE WATER. substances. It dissolves many metals and sulphides of metals forming chlorides, with evolution of hydrogen or of sulphuretted hydrogen. It dissolves oxides and peroxides forming chlorides, in the latter case generally with liberation of chlorine. Salts with insoluble or volatile acids are also converted into chlorides by hydrochloric acid, with separa- tion of the original acid; thus carbonate of lime is converted into chloride of calcium, with liberation of carbonic acid. Hydrochloric acid dissolves salts of non-volatile and soluble acids apparently without decomposing them (phosphate of lime, for example); but the fact is that in cases of this kind a metallic chloride and a soluble acid salt of the acid of the dissolved compound are formed; thus, for instance, in the case of phosphate of lime, chloride of calcium and acid phosphate of lime are formed. With salts of acids which do not form a soluble acid compound with the base present, hydrochloric acid yields metallic chloi-ides, the liberated acids remaining free in solution (oxalate of lime). Hydrochloric acid is also used as a special reagent for the detection and separation of oxide of silver, mercurous oxide, and lead, and likewise for the detection of free ammonia, with which it produces dense white fumes of chloride of ammonium. §29. 2. Chlorine, CI, and Chlorine Water. PreiKhration.—18 parts of common salt in lumps is mixed with 15 parts of finely pulverized good binoxide of manganese, free from carbonate of lime j the mixture is introduced into a flask, a com- pletely cooled mixture of 45 parts of concentrated sulphuric acid with 21 parts of water is poured upon it, and the flask well shaken : a uniform and continuous evolution of chlorine gas will soon begin, which, when it slackens, may be easily increased again by the application of a gentle heat. This method of W i g g e r s is excellent, and can be highly recommended. The chlorine gas evolved is first passed through a flask containing a little water, and then into a bottle filled with cold water, the process being continued until the water is saturated. If chlorine water is required quite free from bromine, the washing flask is changed after about one-half of the chlorine has been expelled, and the gas which then passes over is led into a fresh bottle filled with water. If the chlorine water is wanted quite free from hydrochloric acid, the gas mtist be passed through a U tube containing binoxide of manganese. The chlorine water must be kept in a cellar and carefully protected from the action of light; for, if this precaution is neglected, it soon sufiers decomposition, being converted into hydrochloric acid, with evolution of oxygen (resulting from the decomposition of water). Smaller quantities, intended for use in the laboratory, are best kept in a stoppered bottle protected from the influence of light by a case of pasteboard, or in a black glass bottle. Tests.—Chlorine w^ater shovild smell very strongly of chlorine, and when evaporated in a porcelain basin it must leave no residue. It should contain no hydrochloric acid, or only very little, so that after being agitated with metallic mercury until the odour of chlorine has disappeared, and filtered, the solution should be only faintly acid. Wlien chlorinewater is agitated with bisulphide of carbon and finely divided zinc, the bisulphide should not become even transiently red brown (bromine).](https://iiif.wellcomecollection.org/image/b21966953_0067.jp2/full/800%2C/0/default.jpg)
