SUMMARY. 



INTRODUCTION. 



PAGE 



This bulletin gives the results of experiments begun in 1912 

 and concluded in 1916, intended to provide further 

 data as to the amounts of arsenical residues remaining on 

 fruits and vegetables, after spraying with arsenate of 

 lead, the toxic properties of arsenate of lead, and the 

 possibility of serious poisoning of live stock pastured 

 on forage containing residues of arsenate of lead 8 



Residues on Fruits and Vegetables 9 



In the case of apples, 10 trees were sprayed and various lots 

 of fruit were picked at periods ranging from 5 to 90 

 days after spraying 9 



The fruit was picked in four different ways and these influ- 

 enced the result 12 



When picked carefully, so as not to disturb the poison, the 

 residues were .08 to .77 milligram AS2O3 per apple; 

 when picked in ordinary manner, .02 to .5 milligram 

 per apple; when picked with cotton gloves, .10 to .21 

 milligram per apple; and when picked with cotton 

 gloves and wiped, .08 to .18 milligram per apple 13 



Rain and weather influenced results. Where fruit was 

 picked in the ordinary manner, the residue per fruit 

 decreased 75 per cent when fruit remained 75 to 91 

 days on the tree, as compared with fruit picked 3 to 5 

 days after spraying 14 



Using cotton gloves in picking reduced the residues per 

 fruit one-half, where fruit was picked within 3 to 5 

 days after spraying. This effect diminished where 

 fruit remained longer on the.tree 14 



Experiments in applying spray directly to fruit, in order to 

 determine the maximum that would adhere, showed 

 4.0 milligrams AS2O3 per fruit as the maximum obtain- 

 able. Such fruit gave obvious evidence of spray 

 material on its surface 16 



