78 Intelligeiice and Miscellaneous Articles, 



SEPARATION OF COPPER FROM ARSENIC. 



According to M. Rose, the separation of these metals is to be 

 eifected by decomposing a solution of them by ammonia, and then 

 digesting it for a considerable time in an excess of hydrosulphuret 

 of ammonia, adding to the filtered solution either acetic or muriatic 

 acid, which precipitates the arsenic in the state of a sulphuret. 



M. Buchner having occasion to examine a case of poisoning by 

 Scheele's green, resorted to the above method ; but soon found that 

 the sulphuret of arsenic so obtained contained a notable quantity of 

 copper, notwithstanding the hydrosulpliuret of ammonia had been 

 previously shaken up with a portion of sulphur. The precipitate, 

 on the addition of acetic acid, was of a dirtj?^ flesh-red colour. 



M. Buchner after several trials effected the separation in the fol- 

 lowing manner : — 



The metals were perfectly- precipitated from a solution in muri- 

 atic acid by sulphuretted hydrogen. The precipitate, after being 

 washed with water holding sulphuretted hydrogen in solution, was 

 dried and weighed. 



A portion of this precipitate was mixed with exactly four times 

 its weight of carbonate of potash, and eight times its weight of 

 nitre, and heated in a glass vessel until it melted. The resulting 

 dark bluish gray mass was, on cooling, boiled for some time in a 

 quantity of water. Pure oxide of copper remained imdissolved, 

 which was collected and weighed. The arsenic may be separated 

 from the solution, and the quantity ascertained in the usual manner. 

 A shorter process however is, after the separation of the oxide of 

 copper, to supersaturate the solution by muriatic acid, and ascertain 

 the quantity of sulphur or sulphuric acid by means of barytes. The 

 quantity of sulphur added to the metallic copper, and that deducted 

 from the weight of the combined sulphurets, gives the quantity of 

 the sulphuret of arsenic, from which the weight of the arsenic may 

 be calculated. — Annalen der Physik und Ckemie. J. C. Poggendorff, 

 vol. xliv. p. 137, 1838. 



ON A METHOD OF DISTINGUISHING STRONTIAN FROM BARYTES 

 AND LIME. BY HENRY ROSE. 

 The qualitative examination for strontian is so far difficult as all 

 the substances which precipitate solutions of strontian, also more or 

 less precipitate solutions of l^arytes and lime. In all cases with respect 

 to reagents, strontian stands between barytes and lime. Some re- 

 agents, viz. sulphuric acid, solution of chromate of potash, benzoate 

 of ammonia, iodate of soda, precipitate barytes perfectly from Its solu- 

 tion ; strontian less perfectly, and lime still less so ; other reagents, 

 as the alkaline oxalates, on the contrary, precipitate lime perfectly, 

 strontian imperfectly, and barytes still more imperfectly. Some 

 reagents which do not precipitate strontian or lime perfectly, pre- 

 cipitate barytes, viz. hydrofluosilicic acid ; and there are others 

 which can with certainty distinguisli solutions of barytes or stron- 

 tian from solutions of lime ; as, for instance, solution of sulphate of 



