66 



Preparation of Substances 



Analyses of Paris Green 



AS2O3 



CaO 



(CH3)2(CO).0 

 H2O 



Ke'loe;, 

 average 494 



samples, 

 Penn., 1910. 



57.97 



29.41 



It is noticed that while the arsenic falls 

 about one per cent short the amount of copper 

 oxid is slightly increased as is the acetic aiud, 

 th's may be taken to mean that there is 

 slightly more copper acetate in the compound 

 than is shown by the symbol. 



In the solution from which Paris green is 

 made, arsenite, acetate and copper ions must 

 be in such concentrations, and the tempera- 

 tures so adjusted as to allow the formation 

 of the copper aceto-arsenite. Too much 

 acetic acid will throw the white arsenious oxid 

 out of solution. The reagents must be 

 measured with considerable care to avoid the 

 effect of varying masses. The base and acids 

 concernd are all weak, and the compound is 

 easily hydrolyzed by water; hence the long 

 digestion to allow the formation of large 

 particles in which the ratio of mass to surface, 

 m/s, is greater. 



