446 Notice of some Recent 



It, therefore, appears that the action of copper upon the 

 chlorides is different from that upon the nitrates of mercury. 

 In the latter case, the mercury is reduced and deposited on 

 the copper plate.'^ 



Solubility of Oxide of Lead in Water. — According to 

 Bonsdorff, the oxide of lead when prepared either by the 

 wet way, viz., the action of water containing air upon 

 metallic lead, or by the dry way, from nitrate of lead, is 

 completely soluble in water. One part of lead requires 

 7000 of water for solution, which is not so inconsiderable 

 when we remember that 1 part of magnesia requires above 

 5000 parts of water to dissolve it. The solution of oxide of 

 lead in water possesses a strong alkaline re-action, both on 

 fernambuc and violets, and is an excellent test for carbonic 

 acid.f 



New compounds of Platinum^ — The potash cyanuret of 

 platinum of Gmelin, obtained by mixing together solu- 

 tions of chloride of platinum and ferrocyanodide of potas- 

 sium, evaporating and procuring long fine rhomboidal 

 prisms, which are sometimes yellow and sometimes blue, 

 according as they are viewed, and consisting of K Cy + Pt 

 Cy + 3 Aq, forms with protonitrate of mercury a beautiful 

 smalt blue precipitate. This powder may be washed with 

 cold water, acidulated with nitric acid, and then dried 

 without altering its colour, but if boiled with water it 

 becomes quite white. If a solution of protonitrate of mer- 

 cury be now poured on this bleached precipitate, and be 

 allowed to remain in contact with it for several hours at 

 the usual temperature, it becomes as beautiful as before. 

 When heated on a platinum plate the coloured precipitate 

 detonates, throwing out sparks and smoke. It dissolves in 

 muriatic acid when heated, giving out nitrous and prussic 

 acids. The colourless precipitate burns when heated with- 

 out detonating, and leaves about 38 per cent, of spongy 

 platinum. It dissolves in muriatic acid without disengage- 

 ment of gas. The solution is precipitated by potash, and 

 leaves a residue which decomposes into prussic acid, chloride 

 of mercury, and cyanodide of platinum. When the white 

 precipitate is heated in a small glass retort, it is resolved 

 into cyanogen, running mercury, and cyanodide of platinum. 



• Pharm. Central blatt, Oct. 1836, p. 629. t lb. Au^. 1836, p. h^O. 



