272 Scientific Intelligence. 



very simple method of separating these two metals, by adding carbonate 

 of baryta to the solution containing them, and then passing sulphuretted 

 hydrogen into it. The author, before employing it, wished to ascertain 

 whether in reality no manganese would be precipitated, as stated by 

 M. Barreswil, and mixed for this purpose solutions of the protochlorid 

 and of the protosulphate of manganese with pure carbonate of baryta, 

 and passed sulphuretted hydrogen into them. It was found that nearly 

 the whole of the manganese was precipitated, and the filtered alkaline 

 liquid became turbid on heating to boiling, and contained now not a 

 trace of manganese. This is readily explained by the behavior of car- 

 bonate of baryta towards sulphuretted hydrogen. When a current of 

 this gas is passed into water containing carbonate of baryta in suspen- 

 sion, a portion of it is decomposed in the same way as the alkaline car- 

 bonates, and the liquid contains a considerable quantity of baryta in 

 solution, partly in the form of carbonate dissolved in carbonic acid, 

 partly as hydrosulphuret of barium and hyposulphite of baryta. The 

 very alkaline liquid is rendered turbid by boiling, with separation of 

 carbonate of baryta, and on evaporation to half its volume constantly 

 disengages sulphuretted hydrogen; upon the addition of muriatic acid, 

 this gas and carbonic acid escape, and the liquid is rendered turbid by 

 sulphur; sulphuric acid indicates the presence of a large amount of 

 barytic salts. It is to be hoped that when M. Barreswil next imagines 

 a method, he will test its correctness before publishing it. 



13. Occurrence of Arsenic in Vinegar, (Journ. de Chim. Med., ii, P- 

 334; Chem. Gaz., June 1, 1847, p. 213.)— M. Deschamps found, on 

 preparing pure acetic acid from wood-vinegar, that the latter contained 

 arsenic, which he ascribes to arseniferous sulphuric acid having been 

 used in the manufacture of the pyroligneous acid. As wine-vinegar is 

 frequently strengthened with pyroligneous acid, M. Chevalier was in- 

 duced to examine several samples of ordinary vinegar, and found some 

 of them to contain very perceptible quantities of arsenic. 



14. Mode of detecting the Adulteration of Olive Oil with Rape or 

 Poppy Oil; by M. Diesel, (Archiv. de Pharm. in Chem. Gaz.) 

 Common nitric acid colors pure olive oil green ; a mixture of olive and 

 rape oil produces a yellowish grey color, and with poppy oil a yellow- 

 ish white. After about twelve hours, pure olive oil is itself colored ; 

 the determination must therefore be made before that time has elapsed. 



g. a& , 



15. On a Ready Method of determining the Amount of Nicotine™ 

 Tobacco; by M. Schloesing, (Comptes Rendus, Dec, 1846.)— le 

 grammes of tobacco are to be exhausted with ammoniacal ether, in ^ 

 apparatus for continued distillation, the ammonia expelled by boiling' 

 the solution decanted and the ether evaporated. The amount of nico- 

 tine is then determined by sulphuric acid of known strength, acco" in 

 to the usual alkalimetric method. 



• • 



rdiog 



This process was found to give results closely agreeing with 

 amount determined by a careful separation of nicotine. - a{ 



Tobacco containing a large per cent, of nicotine seems t0 ]f. |f 

 generally preferred for the manufacture of snuff. The snufl »» 

 contains but about one-third of this nicotine, the remainder having D 

 destroyed by the fermentation. This increases the quantity of amm 



