Instruction in chemical analysis : (Qualitative) / With a preface by Prof. Liebig. Edited by J.L. Bullock.
- Carl Remigius Fresenius
- Date:
- 1846
Licence: Public Domain Mark
Credit: Instruction in chemical analysis : (Qualitative) / With a preface by Prof. Liebig. Edited by J.L. Bullock. Source: Wellcome Collection.
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![§ 20.] Uses.—Hydrochloric acid serves as a solvent for a great many substances. It dissolves oxides and peroxides in the form of chlorides, the solution being, in the latter case, mostly attended with liberation of chlorine.—Salts, with insoluble or volatile acids, are also converted by hydrochloric acid into chlorides, with sepa- ration of the original acid; thus carbonate of lime is converted into chloride of calcium, with liberation of carbonic acid. Hy- drochloric acid dissolves salts with non-volatile and soluble acids, apparently without decomposing them, (e. g. phosphate of lime); but we must suppose that solutions of this description arise from the formation of a soluble chloride and of a soluble acid salt of the acid of the dissolved compound ; thus, for instance, in the case of phosphate of lime, we must assume that chloride of calcium and acid phosphate of lime are formed. This explanation, however, will not serve for salts with such acids as form no soluble acid com- pound with the base present; in such cases we must assume, either that the acid of the dissolved salt is present in the solution, in a free state, (borate of lime,) or that the hydrochloric acid acts really as a simple solvent. (Compare § 2.) Hydrochloric acid is also applied as a special reagent for the detection and separation of oxide of silver, protoxide of mercury, and lead, (vide infra,) and likewise for the detection of free ammonia (with which it pro- duces dense white fumes of sal ammonia in the air.) § 20. 2. NITRIC ACID. (N 05.) Preparation.—The nitric acid of commerce contains almost invariably sulphuric acid and hydrochloric acid. To free it from these admixtures, solution of nitrate of silver is to be added to it, as long as any precipitate of chloride of silver continues to form ; this precipitate is allowed to subside ; the supernatant fluid is de- canted into a retort, and distilled to within a small fraction of its whole amount. The distillate is then, if necessary, diluted with water until the specific gravity of the diluted acid is equal to 12.](https://iiif.wellcomecollection.org/image/b29300940_0051.jp2/full/800%2C/0/default.jpg)
