88 ARSENIC AND ANTIMONY. 



The bisulphide of tin is then converted into binoxide 

 of tin, as directed in No. 49. 



The antimoniate of soda is detached as far as possible 

 from the filter, and a mixture of hydrochloric and tar- 

 taric acids poured over the latter, and allowed to flow 

 into the beaker containing the remainder of the preci- 

 pitate. When the salt is perfectly dissolved, and the 

 filter has been washed, the antimony is precipitated by 

 sulphuretted hydrogen. The antimony contained in 

 the precipitate is determined as in No. 55. 



The antimoniate of soda may also be collected upon 

 a weighed filter, dried at 100, and a weighed portion 

 mixed with sal-ammoniac in a porcelain crucible, and 

 ignited, when all the antimony is volatilized, and the 

 salt converted into chloride of sodium. The operation 

 must be repeated several times till the weight is con- 

 stant, and the amount of the antimony may be calcu- 

 lated from that of the chloride of sodium obtained. 



Or the dried antimoniate of soda may be fused in a 

 porcelain crucible with an excess of cyanide of potas- 

 sium. The antimony is reduced and collects in a 

 metallic button. 



61. ARSENIC AND ANTIMONY.* 



If only these two metals be present, as in native 

 arsenic, a complete separation may be effected by heat- 

 ing the compound in a bulb-tube through which a 

 stream of dry carbonic acid gas is transmitted, when 

 the whole of the arsenic is volatilized, and the antimony 

 remains behind. If too strong a heat be applied, a 

 portion of the latter metal may also be volatilized. 



When the compound under examination contains, 

 as is often the case, the two metals in the form of sul- 



* See No. 132. Poisoning by Arsenic. 



