ANALYSES OF PAEIS GREEN. 



493 



cumstances of concentration and heat. Tu moderately concentrated 

 solutions of soda or potash {i.e., sodium hydrate or potassium 

 hydrate) all the copper is removed from Paris green as insoluble 

 cuprous oxide. Soluble soda or potassa arsenite is then formed. 



In such dilute solutions as are here considered, this could not 

 occur, and yet considerable portions of the arsenious acid may be 

 removed from the copper compound. To show this, I have made 

 the following determinations with the use of lime. In each case the 

 Paris green and lime were mixed, placed in the water, the mixture 

 agitated occasionally and at the end of the designated time fil- 

 tered : — 



By substituting for this very large amount of lime smaller quan- 

 tities, proportionally smaller quantities of arsenious oxide were 

 dissolved. 



To illustrate the relative solvent effect in different periods of 

 time, the following determinations serve : — 



Trials with the use of soda save the followina; results : 



