112 MAINE) AGRICULTURAL, EXPERIMENT STATION. I908. 



greens. These impurities will not injure the green in any way 

 for the purpose intended, but they add weight and cause value- 

 less materials to be sold at a high price. 



TABLE SHOWING ORDINARY IMPURITIES OP PARIS GREEN. 



Station Number. 



Brand. 



Water. 



Sand. 



Sodium 

 Sulphate. 



3416 





% 

 1.50 



1.43 



1.36 



1.21 



1.14 



1.14 



% 

 0.12 



0.12 



0.11 



0.20 



0.08 



0.13 



% 

 0.77 



3419 





0.87 



3417 





1.98 



3418 





2.44 



3421 





1.52 



3420 





0.41 









COPPER OXIDE. 



The amount of copper oxide carried by a pure Paris green 

 should be 31.29 per cent. Supposing a green to have 2.75 per 

 cent of impurities, it would then carry 30.42 per cent of copper 

 oxide. While only 4 of the 49 samples carried more than 30.42 

 per cent of copper oxide, 19 of them carried more than 30 per 

 cent. While the presence of the copper oxide is of no impor- 

 tance in itself, a Paris green cannot carry its full content of green 

 unless the copper oxide is practically up to the theoretical. 



ARSENIOUS OXIDE. 



A chemically pure Paris green would carry 58.65 per cent of 

 arsenious oxide in combination with copper. Estimating that 

 there would be 2.75 per cent of impurities, there should be 57.05 

 per cent of arsenious oxide in the green in combination with the 

 copper. Only 15 of the 49 samples carried less than this amount 

 of arsenious oxide; 24 carried between 57 and 58 per cent; 4 

 samples from 58 to 59; one between 59 and 60; 3 between 60 

 and 61 ; and 2 between 61 and 62 per cent arsenious oxide. 

 Viewed from the standpoint of arsenious oxide then, the Paris 

 greens examined would seem to be goods of high grade, but 

 when it is remembered that all the arsenious oxide that is present 

 that is not in combination with copper is a detriment and a dan- 

 ger, it is important to see how much of this arsenious oxide is 

 soluble in water. 



