hitelligence and Miscellaneous Articles. 153 



tartaric acids; from this solution the antimony is precipitated in the 

 form of sulphuret by hydrosulphuric acid gas. 



It is hardly necessary to expel by heat the alcohol from the solution 

 from which the antimoniate of soda has been separated ; it is to be 

 saturated with hydrochloric acid, and without filtering the arseniate 

 of tin which is formed, a current of hydrosulphuric acid gas is to be 

 passed into it. 



Separation of Antimonious and Antimonic Acids. — ^These two acids 

 may be quantitatively determined when they occur together in so- 

 lution in hydrochloric acid, by a solution of gold. This solution of 

 gold is a good substance for discovering the existence of antimonious 

 acid in the presence of a great excess of antimonic acid ; but solution 

 of nitrate of silver is a still more sensible reagent for discovering an- 

 timonious acid. If to a solution of antimonic acid in hydrate of 

 potash, a solution of nitrate of silver be added, an intense black pre- 

 cipitate is obtained. This precipitate is not soluble in ammonia; 

 but it takes this substance from oxide of silver which has been pre- 

 cipitated by an excess of solution of potash ; when a solution of nitrate 

 of silver is added to one of antimoniate of potash, a white precipitate 

 of antimoniate of silver is obtained, with a yellowish tint. If the 

 solution contains free potash, the precipitate of oxide of silver, simul- 

 taneously formed, is brown. The two precipitates are completely 

 insoluble in ammonia. If, on the other hand, the solution contains 

 but a small quantity of antimonious acid, there remains, when the 

 precipitate is treated with ammonia, a black precipitate which does 

 not dissolve. — L'Institut, Decembre 26, 1849. 



ON THE ASSOCIATION OF SILVER WITH METALLIC MINERALS, 

 AND METHODS OF EXTRACTING IT. BY MM. MALAGUTI AND 

 DUROCHER. 



In a former memoir the authors showed that silver exists in many 

 metallic sulphurets, in which its presence had not been suspected, 

 and they are now able to state that most of them contain silver, even 

 when not coming from situations in which this metal is extracted. 

 Thus of more than two hundred specimens examined, only about 

 one-twentieth contained no silver. Many indeed contained traces 

 only, and there would have been some uncertainty if the usual methods 

 of assaying had not been modified. 



It was soon discovered that the humid process is totally inappli- 

 cable in such researches ; litharge was then prepared almost without 

 silver, and the purity of the fluxes and the other reagents employed, 

 was ascertained. Afterwards the conditions under which the fusions 

 should be performed, so as to lose as little as possible, were determined, 

 and they ascertained that buttons of silver, which weighed the six- 

 teenth of a milligramme, did not disappear in cupellation, even when 

 allied with 30 grammes of lead. 



In the experiments performed on the roasting of various sulphurets, 

 the authors were surprised on finding that silver contained in blendes 

 would lose more than half by sublimation. In certain cases this metal 



