A system of instruction in qualitative chemical analysis / by Dr. C. Remigius Fresenius .. ; edited by J. Lloyd Bullock, F.C.S.
- Carl Remigius Fresenius
- Date:
- 1855
Licence: Public Domain Mark
Credit: A system of instruction in qualitative chemical analysis / by Dr. C. Remigius Fresenius .. ; edited by J. Lloyd Bullock, F.C.S. Source: Wellcome Collection.
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![[§ 20. stances. It dissolves lower and higher oxides in the form of chlorides, the solution being, in the case of the higher oxides, mostly attended with libera- tion of chlorine.—Salts with insoluble or volatile acids are also converted by hydrochloric acid into chlorides, with separation of the original acid ; thus carbonate of lime is converted into chloride of calcium, with liberation of carbonic acid. Hydrochloric 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 fromi the formation of a metallic 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] acids forming no soluble acid compound with the base present; in suchij cases we must assume that the acid of the dissolved salt is present in the solution in a free state (borate of lime). Hydrochloric acid is also applied as a special reagent for the detection and separation of oxide of silver,, suboxide of mercury, and lead (see below); and likewise for the detection of free ammonia (with which it produces in the air dense white fumes off chloride of ammonium). § 20. 2. Nitric acid (N 05). Preparation.—Add to nitric acid of commerce, which almost invariably} contains sulphuric acid and hydrochloric acid, a solution of nitrate oit’ silver, as long as a precipitate of chloride of silver continues to form :; let the precipitate subside, decant the perfectly clear supernatant fluid] into a retort, and distil to within a small quantity of the whole amount:; dilute the distillate, if necessary, with water until the specific gravity o?t the diluted acid is equal to 1*2. Tests.—Pure nitric acid must be colorless, and leave no residue , upon evaporation on a platinum knife. The addition of solution o> nitrate of baryta, or of nitrate of silver, must not cause the slightessi turbidity. It is advisable to dilute the acid with water before adding thes*i reagents, otherwise nitrates will precipitate. Uses.—Nitric acid serves, in the first place, as a chemical solvent fo \ metals, oxides, sulphides, oxygen salts, &c. The way in which the nitri acid effects the solution of metals and sulphides, is this : it oxidizes thes* bodies first, at the expense of part of its own oxygen, and converts th t produced oxides subsequently into nitrates. Most oxides dissolve in nitri acid directly as nitrates, and the same is the case with most of the insc luble salts with weaker acids, the latter being expelled by the nitric aciii in the process of solution. Salts with soluble and non-volatile acids ai dissolved by nitric acid in the same manner as by hydrochloric acid. (Se I](https://iiif.wellcomecollection.org/image/b28080361_0048.jp2/full/800%2C/0/default.jpg)
