4 N, H. AGR. EXPERIMENT STATION. [Bulletin 183 



PAGE 



Spraying experiments were carried out with strawberries, 

 currants and blackberries, including two lots of each 

 picked before rain and two lots after rain 19 



With strawberries the residue recovered ranged from 8.6 to 

 34.2 milligrams AS2O3 per quart; with currants 6.8 to 

 10.2 milligrams per quart; with blackbeiries 3.8 to 11.2 

 milligrams per quart 21 



Experiments were carried out with cabbages and lettuce, 

 including two plots of each before rain and two after 

 rain 21 



Results with cabbages showed 43.5 to 51.4 milligrams per 

 head. With lettuce 1.6 to 10.6 milligrams per head. 

 Outer leaves were included 23 



Possible Danger of Human Poisoning 24 



Toxic Standards 24 



The standard medicinal dose of arsenic, AS2O3, is 2 to 5 

 milligrams. The dangerous dose is quoted as 60 to 

 120 milligrams. There is lack of data for drawing com- 

 parison between the toxic properties of arsenic referred 

 to in literature and the possible properties of arsenic in 

 arsenate of lead 24 



Experiments in behalf of this investigation were carried out 

 by Chicago University to determine the solubility of 

 lead arsenate in human gastric juice 25 



The investigation showed that lead arsenate is somewhat 

 soluble in human gastric juice, but probably less so than 

 white arsenic AS2O3 which, therefore, is probably more 

 toxic 27 



Results of Feeding Lead Arsenate and White 

 Arsenic to Guinea Pigs 28 



Experiments were carried out in feeding guinea pigs daily 

 dosefe of arsenate of lead. In parallel experiments, white 

 arsenic in equivalent doses was substituted for lead 

 arsenate 28 



The unit dose fed to guinea pigs was the average maximum 



