Notes on analytical chemistry : for students in medicine / by Albert J. Bernays.

  • Albert Bernays
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: Notes on analytical chemistry : for students in medicine / by Albert J. Bernays. Source: Wellcome Collection.

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    8. Platinum, Pt = 194-5. Dull white metal, malleable and ductile. Sp. gr. 21*5. Melts at about 2000°. Like gold, it does not tarnish in flame, and is easily attacked by chlorine. Platinic chloride PtCl^, is reddish-brown or reddish-yellow, and is the chief salt. By heating PtOl,, platinous chloride PtCl^, is hrst obtained ; then platinum and chlorine. Platinic oxide, PtO^, is black; its hydrate, when dry, brown. Tests for platinic in platinic chloride. Solution strongly acid and colored reddish-yellow. II. HCl-t-IIjS, especially by heat, brown PtS2,HjO, soluble in much am- monium sulphide. KHO generally precipitates potassium platinic chloride, 2 KCl.PtCl^, with yellow color, as platinic chloride is 2 HCl,PtCl4. Excess of KHO gives the yellow hydrate when boiled. NH.HO, gives yellow precipitate of 2 NH,Cl,PtCl„ because the ammonia finds the necessary HCl to make it ammonium chloride. Oxalic acid does not reduce platinic salts. On charcoal, heated in the blow-pipe flame, platinum remains as an in- fusible grey powder, flattened under pestle in mortar to dull white metal. b. Sulphides insoluble in ammonium sulphide, after neutralising free acid with ammonia. Lead, Plumbum, Pb = 207. Chief salts: acetate, nitrate, chloride. See p. 15. If a solution of a lead- salt dilute, although Na^COj wUl have given a white precipitate, HCl will occasion none: lead oxide must be sought for in Group II., sub-division b. 9. Copper, Cuprum, Cu = 63 -3. A lustrous metal of red color, malleable, ductile, and tenacious Sp gr 8-95. Melts at 1300°. Oxydises readUy at a red-heat, forming both red cuprous oxide and black cupric oxide. Sometimes native. Insoluble in ^*'l.fxi.?''/.''^^*°'^ hydrochloric acids: slowly in HCl in presence of air • Cu-f- 2HC1 = CuClj + Hj. With hot sulphuric acid : Cu-f 2 H,SO« = CuSO, -1- 2 H,0 + SO,. With dilute nitric acid: , 3 Cu-f 8 HNO,=3(Cu2N03) +4 H,0-f 2 NO. A good method of making nitric oxide. Chlorine attacks it iramediatelv to cupric chloride. ' Cupric oxide CuO, is the chief oxide. Readily prepared by heating cupric nitrate, CU2NO3, to redness. It is black and quite insoluble in water With 2HCl, into green CuCl^ and H^O. With nitric acid, into blue Cu 2 NO and H,0. With H,SO,, into CuSO, and H,0. Anhydrous cupric sulphate is white ; blue vitriol, CuS0,.5H,0, blue. Cuprous oxide Cu,0 is rubv Conner ore : salts colorless. The chief ore of copper is copper pyrites Fe S Cu S By roasting, the iron oxydised, and slagged off as silicate by further hcitfne with SiO, Sulphur dioxide is given off, and on further calcining the cuprous sulphide, Cu^S, it becomes in part 2CuO-f-SO,. When 2CuO is heated with remaining Cu^S, we obtain 4Cu-|- SO,. Tests for cupric in soluble salts. The commonest are the
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