232 Intelligence and Miscellaneous Articles. 



of copper, it is probable that oxygen may be separated from other 

 metallic oxides; particularly in the case of the metallic acids which 

 easily part with their oxygen. Several trials on metallic oxides 

 gave negative results, but the idea was confirmed with regard to 

 metallic acids. 



Manganesiate of potash was dissolved in water, a caustic alkali, 

 and then arsenite of soda were added; upon mixing, the green co- 

 lour was restored, a dark brown precipitate fell, which was oxide of 

 manganese. 



Chromate of potash was dissolved, caustic alkali and arsenite of 

 soda added, the solution on warming became green. In this case 

 no oxide of chrome fell. The arseniousacid prevented the precipi- 

 tation of the oxide of chrome by means of the alkali, which is evi- 

 dent by the following experiment. 



Hydrated oxide of chrome was dissolved in muriatic acid, to 

 which was added a solution of arsenite of potash: caustic alkali did 

 not give the least trace of oxide of chrome. When to the solution of 

 oxide of chrome in muriatic acid, arsenite of ammonia, fmd then 

 ammonia, were added, no precipitate took place. It is to be re- 

 marked that arsenious acid has also a reducing power over other 

 acids, for example, on molybdic and tungstic acid, but for want of 

 these acids I was unable to make the necessary experiments. — 

 Poggendorff"s Annals, 1836, No. 2. 



ON THE COMPOSITION OF PLAGIONITE. BY RUDERNATSCH. 



This mineral has been analysed by Professor H. Rose, who found 



it to consist of Lead 40-52 



Antimony 37'94 



Sulphur 21-53 



and has given the formula of4 Pb S -|-3 Sb S^ 



As this combination of sulphur in sulphuret of antimony is in a very 

 uncommon proportion to the sulphuret of lead, namely as 9 to 4, and 

 as Berzelius, in his Jahresbericht, has thrown some doubt on the ex- 

 istence of such a compound, which he considers likely to be a mixture 

 of the two, Mr. Rudernatsch was induced to repeat the examination 

 of some very distinct and well-defined crystals : he followed the same 

 mode of analysis as Professor Rose, which gave the following results : 



Lead 40-98 



Antimony 37'53 



Sulphur 21-49 100- 



In a second analysis, which was only to determine the quantity of 

 lead, he found 40-8 I per cent. 



It therefore appears, by these analyses, that plagionite is a peculiar 

 chemical combination. — Poggendorff's Annals, 1836, No. 4. 



ON SOME TRIPLE COMBINATIONS OF CHLORIDE OF OSMIUM 

 IRIDIUM AND PLATINUM WITH CHLORIDE OF POTASSIUM 

 AND MURIATE OF AMMONIA. BY R. HERMANN OF MOSCOW. 

 1. — Triple Salt of Chloride of Osmium and Chloride of Iridium 



toith Chloride of Potassium. — When the native mixture of iridium 



I 



