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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![NITRATE OF PROTOXIDE OF COBALT. I ses.—On heating phosphate of soda and ammonia, tlie ammonia escapes with the wntev of ciystalHzation, leaving acid pyrophosphate of soda, NaO,HO,PO, [Na,H,P,p,]; when this is heated more strongly, the last equivalent of water escapes likewise, and the readily fusible meta- phosiDhate of soda, K'aO,PO, [NaPO,], is left. The action of microcos- mic salt is analogous to that of biborate of soda. In some cases, however, it is preferable to use borax as a solvent or flux, the beads which it forms with many substances being more beautifully and distinctly coloured than those of borax. Platinum wire is also used for a support in tlie process of fluxing with microcosmic salt; the loop must be made small and narrow, otherwise the bead will not adhere to it. The operation is conducted as directed for borax on p. 81. § 85. 5. Nitrate of Protoxide of Cobalt, CoO,m [CoiNOay. Crystallized, CoO,NO. + 6aq [Co(N03)2,6H20]. _ Preparation.—GommeveM oxide of cobalt is dissolved in hydrochloric acid, the solution evaporated to dryness on the water-bath, and tlie residue dissolved in water; carbonate of baryta made into a cream mtli water (§ 60) is then added in excess, the mixture allowed to remain for some hours, with frequent stirring, filtered, and the residue washed. More carbonate of baryta is now added to the filtrate, chlorine passed in, and the whole allowed to remain for a considerable time, shaking repeatedly; the precipitate, consisting of peroxide of cobalt and the excess of carbonate of baryta, is separated from the solution which con- tains the nickel, thoroughly washed, dissolved in hydrochloric acid, sul- phuric acid added in slight excess to precipitate the baryta, and sul- phuretted hydrogen passed into the mixture (without filtering) heated to 70°. The product is filtered, ammonia added to the filtrate to alka- line reaction, then sulphide of ammonium in excess, and lastly acetic, acid to acid reaction; the sulphide of cobalt thus precipitated is col- lected, washed, dissolved in nitro-hydrochloric acid, and the excess of acid removed by evaporation. The residue is next dissolved in water, and the hot solution precipitated with carbonate of soda; the preci- pitate is well-washed, and treated while still moist with oxalic acid in excess. _ The rose-red oxalate of protoxide of cobalt is thoroughly washed, dried, and heated to redness in a glass tube, in a current of hydrogen; this decomposes the oxalate into carbonic acid, which escapes, and metallic cobalt, which is left behind. The metal is washed, first with water containing acetic acid, then with pure water, dissolved in dilute nitric acid, and evaporated to dryness on the water bath. 1 part of the residue is dissolved in 10 parts of water for use. Tests.—Solution of nitrate of protoxide of cobalt should be free from other metals, and especially from salts of the alkalies ; no fixed residue should be left when the solution is precipitated with sulphide of am- monium, filtered, and' the filtrate evaporated on platinum. When treated with cyanide of potassium in excess, adding soda if necessary, it should not give the slightest black precipitate of hydrated oxide of nickel even after remaining for an hour. Uses.—When protoxide of cobalt is ignited with certain infusible compounds (oxide of zinc, alumina), it forms characteristically coloured compounds, and may accordingly serve for their detection.](https://iiif.wellcomecollection.org/image/b21966953_0106.jp2/full/800%2C/0/default.jpg)
