234 Intelligence and Miscellaneous Articles. 



and its quantity noted ; the water formed by the combustion of the 

 hydrogen was collected and weighed in absorption tubes. 



The zinc employed was purified by M. Jacquelain's method, and 

 to render it attackable by sulphuric acid it was placed in a platina 

 vessel ; the quantity of zinc employed in these operations was not 

 less than 246 grains, and amounted in some cases to 1047 grains. 



Assuming 12'5 as for the equivalent of hydrogen, the following 

 were the numbers obtained, in these experiments, for that of zinc : 

 I. II. III. Mean. 



412-27 411-77 41242 412-16 



These figures evidently represent a multiple of the equivalent of 

 hydrogen by 33. They agree very well with those obtained by the 

 first method : 



Equivalent by the first method .... 41 2' 63 

 Equivalent by the second method . . 4 12- 16 



Mean 412-395 



The equivalent of hydrogen being 1, that of zinc will then be repre- 

 sented by 32-991, very near 33. — Journ. dePh. et deCh., Janvier 1844. 



MODE OF DISTINGUISHING ZINC FROM MANGANESE WHEN 

 DISSOLVED IN AMMONIACAL SALTS. BY M. OTTO. 



When a solution of hydrochlorate of ammonia containing the chlo- 

 rides of zinc and manganese is rendered alkaline by a small quantity 

 of ammonia, and a little hydrosulphuric acid is added, a white pre- 

 cipitate of sulphuret of zinc free from sulphuret of manganese is 

 formed ; in order that the latter may be produced, a larger quantity 

 of hydrosulphuric acid must be added. It is always easy to distin- 

 guish and separate these two sulphurets one from the other ; to 

 effect it, excess of acetic acid must be added to the liquid, by which 

 the sulphuret of manganese will be dissolved, while that of zinc will 

 remain unacted upon. Thus to determine whether iron contains any 

 brass, the metal is to be dissolved in aqua regia, and ammonia is to 

 be added to the acid solution to precipitate the peroxide of iron ; 

 into the liquor, filtered and rendered acid, a current of hydrosulphu- 

 ric acid is to be passed, which precipitates the copper in the state of 

 sulphuret ; after its separation ammonia is added to the menstruum, 

 and, as this contains hydrosulphuric acid, a white precipitate of sul- 

 phuret of zinc is formed, which is insoluble in acetic acid. M. Otto 

 objects to the employment of hydrosulphate of ammonia, as it 

 almost always contains persulphuret, the sulphur of which is preci- 

 pitated by the acetic acid, and this being white and insoluble in 

 acetic acid, may be confounded with sulphuret of zinc. M. Wack- 

 enroder has recommended the formation of sulphuret of manganese 

 as a means of separating it from all other metals, on account of its 

 solubility in acetic acid. — Jour, de Pharm. et de Ch., Janvier 1844. 



PREPARATION OF PROTIODIDE OF IRON. BY M. MIAI.HE. 



The author remarks that it is generally supposed that the above- 

 named salt cannot be prepared in contact with the air and obtained 

 in a solid state in a state of purity, and he admits that in fact it ge- 



