112 Notice of some Recent [Feb. 



independent oxidation of the protoxide, and are not con- 

 nected with the gas absorbed ; and this is further proved 

 by the fact, that if the solution is evaporated in a vacuum, 

 the gas disappears, and the salt remains unaltered. It 

 may be observed, however, that ferro-prussiate of potash, 

 does not produce a Prussian blue colour, with the salt in 

 this state, but forms a reddish brown flocky precipitate, 

 which changes its colour to blue on exposure to the air. 



Phosphate of soda, as well as all salts which by double 

 decomposition produce insoluble precipitates, with the 

 salts of protoxide of iron, form when the last salts are 

 saturated with deutoxide of azote, compounds in which the 

 gas remains in combination. The precipitate occasioned by 

 phosphate of soda is reddish brown, and passes in the air 

 into phosphate of iron. But these combinations are so 

 extremely unstable, that it becomes almost impossible to 

 study their nature. 



With regard to the other metallic solutions the effect is 

 quite different. The gas is absorbed by chloride of tin and 

 nitrate of mercury, but the chloride decomposes the 

 deutoxide of azote, and takes up the oxygen necessary to 

 produce an oxide of tin. A solution of nitrate of mercury 

 saturated with the gas, deposits speedily a crystallized salt 

 which is a hyponitrate and less soluble than the nitrate. 



The circumstances to which we have directed our atten- 

 tion above, deserve to be prosecuted, as they have no 

 analogy in mineral chemistry. 



Reduction of Chloride of Silver, (Journal de Chimie d'Erd- 

 mann, 1833, p. 270. J — The best method of reducing chloride 

 of silver is that of Mohr, which consists in mixing the 

 chloride with the third of its weight of colphane, and 

 heating the mixture moderately in a crucible until the 

 flame ceases to be of a greenish blue colour, then to increase 

 the heat, for the purpose of fusing the silver and collecting 

 it at the bottom of the vessel. 



BASES. 



Method of procuring Selenium. — Brunner employed, for 

 the purpose of extracting selenium, the refuse from the 

 sulphuric acid manufactory at Luckawitz, in Bohemia, 

 (Poggendorff, Ann. xxxi.) The dried refuse is to be distilled 



