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.
95/526 page 71
![67, 68.] chloride of barium, is useful in effecting the separation and classification of acids into groups. ... Most of the insoluble compounds of sUver dissolve m dilute nitric iicid; chloride, bromide, iodide, and cyanide, ferrocyanide, ferricyanide, and 'sulphide of silver, however, are insoluble in that menstruum. Nitrate of silver is therefore an excellent reagent for distinguishing and separating the hydracids corresponding with the last enumerated com- pounds of silver from all other acids. Many of the insoluble salts of silver are of a pecuHar colour (chromate of silver, arsenate of sUver), or exhibit a characteristic behaviour with other reagents or on the application of heat (formate of silver) ; nitrate of silver is therefore an important agent for the detection of certain acids. § 67. 4. Acetate of Lead, PbO,C,H303 = PbO,A [PbCC.H,©,),]. Crystallized, PbO,C,H303 + 3aq [Pb{aHp,)„3H,0]. The best commercial acetate of lead (sugar of lead) is sufficiently pure ; for use, 1 part of the salt is dissolved in 10 parts of water. Tests.—Acetate of lead should dissolve completely in water acidified with one or two drops of acetic acid; the solution should be quite clear find colourless; sulphuretted hydrogen should throw down all the fixed matter from it. On mixing a solution of acetate of lead with car- bonate of ammonia in excess, and filtering the mixture, the filtrate should be quite free from any bluish tint (copper). Uses.—With a great many acids, oxide of lead forms compounds insoluble in water, which are marked either by peculiarity of colour or characteristic behaviour; acetate of lead therefore yields precipitates with the solutions of these acids or of their salts, and materially con- tributes to the detection of several of them. Chromate of lead, for instance, is characterized by its j'-ellow colour, phosphate of lead by its peculiar behaviour before the blowpipe, and malate of lead by its ready fusibility. § 68. 5, Mercurous Nitrate or Nitrate of Suboxide of Mercury, HgP,NO^ [Hg.lNOJ,]. Crystallized, Hg,0,N0. + 2aq [Hg,(N03)2,2H,0]. Preparation.—1 part of pure nitric acid of 1'2 sp. gr. is poured on to 1 part of pure mercury in a porcelain dish, and the vessel allowed to remain for twenty-four hours in a cool place; the crystals which are formed are separated from the undissolved mercury and the mother liquor, and dissolved by grinding them up in a mortar with water which has been previously mixed with one-sixteenth part of nitric acid. The solution is filtered and kept in a bottle with some metalKc mercury sufficient to cover the bottom of the vessel. Tests.-—With dilute hydrochloric acid, the solution of mercurous nitrate should give a copious white precipitate of mercvirous chloride; /sulphuretted hydrogen should produce no precipitate in the filtrate from this, or at most only a trifling black precipitate (sulphide of mercury).](https://iiif.wellcomecollection.org/image/b21966953_0095.jp2/full/800%2C/0/default.jpg)
