of potash and sulphate of copper are mixed, a light green pre- Sect, XXVII. cipitate falls. When heated it becomes azure-blue, and by a stronger heat, dark-green, then white, and at last black, when it catches fire and burns with a pale flame and much smoke. The salt is insoluble in water. Its constituents are Camphoric acid 61. Suberate of copper. Suberate of ammonia throws down a light blue precipitate from the cupreous salts. When dry it is bluish-green, and is composed of It is little soluble in water. When heated it melts and undergoes decomposition.+ 62. Butyrate of copper. It may be obtained by dissolving carbonate of copper in an aqueous solution of butyric acid. It crystallizes in eight-sided prisms, with an oblique base. When kept in vacuo over sulphuric acid it loses 1 per cent. of its weight; and becomes less transparent. When heated to 212° it loses no acid. But at that temperature the aqueous solution becomes muddy and deposites oxide of copper. It is composed, according to Chevreul, of Butyric acid Oxide of copper This is equivalent to 1 atom oxide of copper 2 atoms water 57.04 29.63 13.33 100.00 9.625 10 2.25 21.875 63. Cholesterate of copper. 64. Pinate of copper. An olive-green salt. An alcoholic solution of pinic acid when boiled over oxide of copper gradually combines with it. * Brandes, Schweigger's Jour. xxxviii. 297. Sur les corps gras, p. 130. Ibid. xxxiii. 97. Class I An ethereal solution of pinic acid dissolves carbonate of copper with effervescence. It decomposes also borate and benzoate of copper. We may obtain pinate of copper by mixing pinate of potash with an aqueous solution of a cupreous salt. It is a green powder, which at 212° begins to concrete, and in a higher temperature is converted into a resinous looking mass, of a darker-green colour. In a still higher temperature it is converted into pinated suboxide of copper. It is insoluble in water, very little soluble in absolute alcohol or naphtha, but very soluble in ether, oil of turpentine, and fat oils. The ethereal solution is dark-green, and when concentrated, deposites the salt in crystalline sphericles. When the solution in oil of turpentine is exposed to the air it gradually dries into a green transparent varnish. This salt is composed of Pinic acid Oxide of copper. 100 7.4 65. Silvate of copper. Very similar to the preceding salt. It is soluble in absolute alcohol, from which it is deposited by spontaneous evaporation in brilliant crystalline grains. Its solution in ether has more of a blue colour than that of pinate of copper.+ 66. Carbazotate of copper. This salt is obtained by mixing solutions of sulphate of copper and carbazotate of barytes in the requisite proportions. The crystals form with difficulty. They have a fine green colour, and deliquesce in the air. When heated the salt undergoes decomposition without burning with flame. 67. Pururate of copper. Pyrurate of potash throws down a precipitate when dropped into sulphate of copper.§ 68. Hydro-carbo-sulphate of copper. Hydro-carbo-sulphate of potash throws down a fine yellow precipitate when dropped into a cupreous salt. 69. Sulphovinate of copper. This salt may be formed by dissolving carbonate of copper in sulphovinic acid, and evapor ating the solution. It crystallizes in blue coloured four-sided tables with sharp edges. It is very soluble in water, it dissolves also in alcohol. When heated to redness it burns with flame and leaves sulphate of copper.¶ • Unverdorben, Poggendorf's Annalen, xi. 233. + Ibid. p. 100. 70. Sulphonaphthalate of copper. Hydrated oxide of copper Sect.XXVIII. forms an acid salt when digested in sulphonaphthalic acid, and the solution by spontaneous evaporation leaves radiated crystalline films. The dry salt when heated fuses and burns with flame.* 71. Sinapate of copper. When sinapic acid is added to a solution of sulphate of copper it changes its colour to green, and in about an hour a white powder is deposited.† SECTION XXVIII.-SALTS OF SUBOXIDE OF copper. This genus of salts has been very little investigated. These salts, so far as known at present, are never green or blue, but red, brown, or black. When exposed to the air they speedily absorb oxygen, and are converted into the corresponding salts of black oxide of copper. 1. Sulphated suboxide of copper. This salt may be obtained by decomposing sulphate of copper by means of phosphorus. A black powder falls, which requires to be rapidly washed and dried. It dissolves in nitric acid with the evolution of deutoxide of azote.‡ 2. Sulphited suboxide of copper. Sulphurous acid combines only with the suboxide of copper, the black oxide having the property of converting it into sulphuric acid. Sulphited suboxide of copper may be formed by passing a current of sulphurous acid gas through water containing black oxide of copper mixed with it. The oxide is gradually converted into suboxide by giving out one half of its oxygen to a portion of the sulphurous acid, which it converts into sulphuric. The sulphited suboxide of copper remains in the state of small red crystals, while the sulphate dissolves in the water. This salt may be obtained also by mixing a solution of sulphate of potash with a solution of nitrate of copper, and washing the yellow precipitate that falls till it becomes red. It is in the state of small red crystals. It is insoluble in cold water, but when long boiled in water, the whole of its acid is separated and nothing remains but suboxide of copper. When heated it gives out water, sulphurous acid, a little sulphur, and some sulphate of copper is formed. Potash and soda readily deprive it of its acid. Chlorine and nitric acid convert it into sulphate of copper. According to Chevreul, to whom we are indebted for the whole of the preceding facts, this salt is composed of • Faraday, Annals of Philosophy (2d series), xii. 210. + Henry and Garot. Berzelius, Ann. de Chim. et de Phys. ii. 228. sol-aide of copper. This salt may be hyposulphite of lime on carbonate of coplf Late of copper with hyposulphite of lime, It is colourless, of an intensely sweet taste, fola mawkish sweetness like liquorice root, but with no favour. It is not decomposed, nor turned blue by 4. Nte ted sidwide of copper. This salt does not exist, nitric acid has the property of converting suboxide of to black oxide. todskocide of copper. This salt may be formed by rated suboxide of copper in selenious acid. It is wder, not soluble in water. ted si lucide of copper. When crystallized verdigris this salt sublimes towards the end of the distillation in vildre flocks, which, according to Berzelius, contain no 11 Its taste is caustic and astringent, and it reddens litpaper. It undergoes no change when exposed to the air. er is poured on it suboxide of copper precipitates in yellow flocks. It is partially soluble in alcohol, leaving a yelw powder undissolved.† This salt was mistaken by Proust for anhydrous acetate of copper. 7. Vinted suboride of copper. Copper dissolves very slowly in vinic acid. After some days the solution deposites a greenish-blue salt, and then by concentration deposites white oblique rhombie prisms, soluble in water, and precipitated by potash in yellow flocks. * Ann. de Chim. Ixxxiii. 181. ↑ Walchner. Berzelius and Gehlen. 8. Pinated suboxide of copper. When pinic acid is fused Sect. XXIX. with carbonate or acetate of copper till the acids are expelled, and the mixture, at first green, has become brown and transparent, and the excess of pinic acid is removed by alcohol, pinated suboxide of copper is formed. A brownish-yellow powder. It is but little soluble in ether, but more soluble in oil of turpentine. The solutions speedily absorb oxygen and become green.* 9. Silvated suboxide of copper. Easily soluble in ether.† SECTION XXIX.— SALTS OF OXIDE OF BISMUTH. The salts of bismuth may be distinguished by the following properties: 1. The solution of bismuth in acids is usually colourless. Characters. When water is poured into it a white precipitate immediately falls, consisting chiefly of the white oxide of bismuth. 2. Prussiate of potash occasions in these solutions a precipitate of a white colour, sometimes with a shade of yellow. 3. Hydrosulphuret of potash and sulphuretted hydrogen occasion a dark-brown precipitate. 4. Gallic acid and the infusion of nut-galls occasion an orange-yellow precipitate. 5. When a plate of copper or tin is put into the solution of bismuth, this last metal is often precipitated in the metallic state. 1. Sulphate of bismuth. This salt may be obtained by heating bismuth in sulphuric acid. The metal is converted into a white powder, while at the same time sulphurous acid is exhaled, and even sulphur sublimed, if the heat be considerable. When the saline mass thus formed is washed with water, twothirds of the acid are separated, carrying along with them a very small portion of the oxide, and this lixivium yields by evaporation small crystals in needles, which are decomposed, and their base precipitated when any attempt is made to dissolve them in water. According to the experiments of Lagerhjelm, the sulphate of bismuth is composed of Sulphuric acid Oxide of bismuth 100 197.5 This is obviously * Unverdorben, Poggendorf's Annalen, xi. 233. + Ibid. |