June, 1917.] ARSENICAL RESIDUES AFTER SPRAYING. 



43 



02 



o 



O 



w. 



O 



Q 



« 

 P 



<! 



> 



o 





1 

 6 





4 



o 



>0 



-is 



n 



r 

 1 



V) 



n 



u 



'4 



5 



IS 



cvj 



'O 



