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.
53/412 page 31
![§ 22.] chloronitric acid gas, but it recommences the instant that this state of saturation is disturbed by the application of heat, or in consequence of the decomposition of the chloronitric acid. The chlorine and part of the oxygen of this acid are held in combina- tion by a very feeble affinity only; the presence of this acid ren- ders aqua regia therefore the most powerful solvent for metals, with the exception of those which form insoluble compounds with chlorine.—Aqua regia serves principally to effect the solution of gold and platinum, (which metals are insoluble both in hydro- chloric and nitric acid,) and the decomposition of divers sul- phurets, e. g. cinnabar, &c. &c. § 22. 4. ACETIC ACID. (C^H3 03 =A.) Preparation.—Triturate ten parts of crystallized neutral acetate of lead, with three parts of effloresced sulphate of soda; intro- duce the powder into a retort, add a refrigerated mixture of two and a half parts of sulphuric acid with an equal weight of water, and distil to dryness in a sand-bath. The most appropriate way of connecting the receiver with the retort, is by means of a Liebig’s condensing apparatus. Tests.—Pure acetic acid must leave no residue upon evapora- tion. The diluted acid ought not to be precipitated by sulphu- retted hydrogen, nor by solution of nitrate of silver or nitrate of barytes, by the latter not even after previous ebullition with nitric acid. Should nitrate of barytes produce a precipitate in acetic acid which has been previously boiled with nitric acid, this is a proof of the presence of sulphurous acid; the acetic acid in such cases is to be digested with brown peroxide of lead, and subse- quently redistilled. Pure acetic acid, moreover, must not decolor solution of indigo. (Vide § 102, a.) Uses.—Acetic acid possesses a greater solvent power for some substances than for others;—it is used, accordingly, to separate the former from the latter; thus it serves, for instance, to distin-](https://iiif.wellcomecollection.org/image/b29300940_0053.jp2/full/800%2C/0/default.jpg)
