262 KANSAS UNIVERSITY QUARTERLY. 



hydrochloric acid with the addition of KCIO3, if necessary, the 

 chlorine driven off by gentle heat and the solution treated as 

 before. 



Since a concentrated solution of hydrochloric acid becomes 

 weaker on heating it will be necessary to add more acid before 

 passing in the hydrogen sulfid. 



Of course after this treatment everything will be in the highest 

 oxidized condition and hence the original solution must be tested 

 for their condition there. 



The dark color of the stannous sulfid is much more intense than 

 the yellow of the stannic, so it is well in many cases to reduce the 

 tin by dissolving a small fragment of zinc in the solution before 

 passing in the hydrogen sulfid. 



