26 



N. H. AGR. EXPERIMENT STATION. 

 Series II. 



[Bulletin 183 



0.5 gr. lead arsenate 

 25 cc. human gastric juice 

 25 cc. distilled water 

 25 gr. apple pulp 



at 38° C. for 12 hours 



Series III. 



0.2 gr. lead arsenate ] 



25 cc. human gastric juice i at 38° C. for 12 hours 



25 cc. milk J 



In Solution. 



The arsenate of lead, especially as prepared for commercial use as an insecti- 

 cide, is probably not a definite compound.* According to the analysis fur- 

 nished us by Professor O'Kane, the lead arsenate used by us contained 0.18 

 per cent moisture, and yielded 33.4 AS2O5. We ran two analyses of the lead 

 arsenate itself with the following results: 



1. 0.25 gr. lead arsenate, j'ielded 



2. 0.25 gr. lead arsenate, yielded 



/ PbS04 =0.1794 gr. 

 \ Mg2As207 = 0.1006 gr. 

 / PbS04 = 0.1843 gr. 

 \ Mg2As207 = 0.1010 gr. 



On the basis of these figures it is clear that about 5 per cent of the arsenates 

 of lead are dissolved in human gastric juice when mixed in the proportion of 

 0.5 gr. lead arsenate to 25 cc. of the juice. It is probable that the essential 

 solvent in the gastric juice is the free hydrochloric acid, so that by increasing 

 the quantity of the gastric juice, or reducing the quantity of the lead arsenate, 

 the percentage of the arsenate dissolved in the gastric juice is correspondingly 

 increased. 



* Tartar and Robinson. Jr. Am. Ch. Soc, 1914, XXXVI, p. 1843. 



