32 



PARIS GREEN SPRAYING EXPERIMENTS. 



soluble arsenious oxid allowable is between 3 and 8+ per cent, a fair 

 average being 6 per cent. 



(4) For pear trees sprayed with the use of lime the amount of solu- 

 ble arsenious oxid allowable is between 5 and 8+ per cent, a fair 

 average being 7 per cent. 



(5) For plum trees sprayed without the use of lime the amount of 

 soluble arsenious oxid allowable is between 3 and 8+ per cent, a fair 

 average being about 4 per cent. 



(6) For plum trees sprayed with the use of lime the amount of solu- 

 ble arsenious oxid allowable is between 4 and 8+ per cent, a fair aver- 

 age being from 5 to 6 per cent. 



(7) In spraying peach trees none of the Paris Greens bought upon 

 our market should be used without the addition of lime. 



(8) For peach trees sprayed with the use of lime the amount of solu- 

 ble arsenious oxid allowable lies between 3 and 6 per cent, a fair aver- 

 age being 4.5 per cent. 



(9) The difference in the effect produced by Paris Greens used with 

 and without the addition of lime is so great that lime should always be 

 employed. 



For ready reference these conclusions are also embodied in the 

 following table: 



Maximum and average amounts of soluble arsenious oxid allowable. 



It is evident that the amount of soluble arsenious oxid allowable in 

 a Paris Green depends largely on the kind of fruit tree that is to be 

 sprayed. The author is of the opinion that State chemists should not 

 select any fixed standard by which to judge all Paris Greens sent in 

 by the farmer, but should find out for what purpose the green is to 

 be used and base his decision on the resisting power of the kind of 

 tree to be sprayed. It would perhaps be advisable to have a printed 

 form giving the names of the various common fruit trees and to state 

 after each whether or not the sample sent could be used upon it. 



O 



