Cupric double sulphates

The specific volumes.—P. Kremers (1856) B and P. A. Favre and C. A. Valson (1873) argued that if the volume of a mixture of soln. of two salts in molecular proportions is equal to the sum of the volumes of the component soln. before mixing no double salt is formed in soln. Thus, it was inferred that potassium cupric sulphate does not exist as a double salt in aq. soln. and that the double salt must be born at the moment of crystallization. G. T. Gerlach, however, found that some salts behave in the converse way, and hence may be supposed to form complexes in aq. soln. 

According to H. Rose, the blue soln. of cupric hydroxide in cold hypophosphorous acid may remain unaltered for a long time and if very dil., it may even be heated without decomposition. If the soln. be evaporated in vacuo at a low temp., the copper is completely reduced as soon as the liquid is highly concentrated. C. A. Wurtz found that the soln. obtained by double decomposition of barium hypophosphite and copper sulphate at about 60° precipitates copper hydride— vide supra. Once blue crystals of copper hypophosphite, Cu(H2P02)2, were obtained they decomposed abruptly at 65°. According to R. Engel, this salt... 

In alcoholic solution cupric sulphate combines with nitric oxide to form a double compound of the formula CuSO NO.8... 

Double Copper Selenates.—Tutton11 has investigated the crystallographic properties of double selenates of the series R2Se04,CuSe04,6H20, R representing potassium, rubidium, caesium, or ammonium. They are isomorphous with the monoclinic double salts formed by cupric sulphate with the sulphates of potassium, rubidium, caesium, and ammonium.12... 

Manganous Sulphate—Mangani anlpiui (f. ST.)—MnSO -f Aq—150 4-nl8—is forineil by the action of H.BO on MnO. Below 6 (42 .8 F.) it crvstallizes with 7 Aq, and is isomorphous with ferrous sulphate j between 7 -20 (44 .6-68 F.) it forms cryTitiUs with 5 Aq, and is isomorphous with cupric sulphate between 20 -30 f68 = -66 = F.) it cnstallizes with 4 A. It is Tose-colored, darker as the proportion of Aq increases soluble m H.O, instduble in alcohol. With the alkaliue sulphates it forma double salts, with 6 Aq. 

Cyanogen is more conveniently prepared by warming an aqueous solution of copper sulphate and potassium cyanide. A double decomposition between the two salts results in the formation of cupric cyanide and potassium sulphate. The former, at a comparatively low temperature, decomposes with the formation of cuprous cyanide and cyanogen. The reactions are expressed by the equations,—... 

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