BY FRANK E. CONNAH. 67 



sulphide, and titrate with the coppor sulphide precipitate 

 present. If the sodium sulphide be used in the form of 

 crystal, the copper sulphide forms a dark precipitate, 

 whereas if a solution were used a brown ooloratioL of the 

 liquid would result, which would interfere with the sub- 

 sequent titration. 



