186 Notices of the Labours of Continental Chemists. 



chloric and arsenious acids. This decomposition is perfectly 

 similar to that which is caused by water in the precipitate pro- 

 duced in solutions of the perchloride of mercury by phosphu- 

 retted hydrogen, only that it is effected more rapidly. The 

 similar decomposition of both precipitates by water, and also 

 by dilute nitric acid, supposes a similarity in their constitution, 

 which was confirmed by a quantitative analysis, according to 

 which the precipitate proved to be composed according to the 

 formula As 2 Hg 3 + 3 Hg CI. This precipitate differs from 



that produced by phosphuretted hydrogen, by its being anhy- 

 drous, while the latter contains three atoms of water. This 

 is the reason of their different action at a high temperature. 

 The precipitate produced by antimoniuretted hydrogen in so- 

 lutions of the perchloride of mercury, has quite a different 

 composition to that produced by phosphuretted or arseniuret- 

 ted hydrogen in such solutions. Whence we may conclude 

 that the composition of antimoniuretted hydrogen differs from 

 those of phosphuretted and arseniuretted hydrogen. (H. 

 Rose in Pogg. Ann. li. p. 423.) 



On the Salts of head formed, by Nitrous Acid and Hyponitrous 



Acid. 

 Proust was the first to observe that lead dissolves in con- 

 siderable quantity when brought into a hot solution of the ni- 

 trate of lead; the salt thus produced is deposited in the form 

 of yellow lustrous scales. Proust concluded from this expe- 

 riment that the oxide of lead was reduced to a lower degree 

 of oxidation; however, Berzelius subsequently showed that 

 the solution of the lead was effected at the expense of the ni- 

 tric acid in the salt employed. About the same time Chevreul 

 described two different salts produced by the action of differ- 

 ent quantities of lead on the nitrate of lead, and arrived at 

 nearly the same conclusions as Berzelius. Peligot has re- 

 cently shown that three very distinct salts are formed by the 

 action of lead on the nitrate of lead, two of which contain not 

 nitrous acid*, as supposed by Berzelius and Chevreul, but hy- 

 ponitric acidt; accordingly the latter acid, which, according 

 to Dulong's analyses, consists of two volumes of nitrogen and 

 four of oxygen, would, contrary to the general opinion, be 

 able, if not to combine directly with bases, yet at least to 

 exist in combination with them. Proust's salt is best pre- 

 pared by bringing together one equivalent of lead and one 

 equivalent of the nitrate ; the reaction proceeds to the last at 

 a temperature below 60° or 70°, without any evolution of ni- 



* Hyponitrous acid of the English chemists, 

 f Nitrous acid of the English chemists. 



