June, 1917.] ARSENICAL RESIDUES AFTER SPRAYING. 25 



the other hand, if mixed with waier to form a spray material, is 

 apt to burn the foliage of plants severely. 



It will be noted that this does not take into account possible 

 poisoning by lead. We are here concerned with the arsenic 

 rather than the lead, because the latter can hardly be present in 

 sufficient quantities to cause acute poisoning from a single or a 

 few doses if the arsenic is not present in sufficient quantity. 



SOLUBILITY OF LEAD ARSENATE IN HUMAN GASTRIC JUICE. 



Thru the kindness of Dr. A. J. Carlson and Dr. A. Woelfel, of 

 the Hull Physiological Laboratory, Chicago University, experi- 

 ments were carried out to provide data relative to the solubility 

 of arsenate of lead in normal human gastric juice. 



The report of these investigators is here quoted verbatim: 



THE SOLUBILITY OF LEAD ARSENATE IN HUMAN GASTRIC JUICE. 



A. J. Carlson and A. Woelfel. 

 (From the Hull Physiological Laboratory of the University of Chicago.) 



The following tests were made at the request of Prof. W. C. O'Kane of the 

 New Hampshire Agricultural Experiment Station. Lead arsenate is used as 

 an insecticide in the spraying of fruit trees, and is therefore liable to be in- 

 gested with such fruit as is not peeled before being eaten. The lead arsenate 

 used in these tests was sent us by Professor O'Kane. 



In the present series of tests we followed the procedure of our previous 



investigations of the solubility of other lead compounds in human gastric 



juice.* The gastric juice was obtained from Mr. V., our man with permanent 



gastric fistula.f The free acidity of the gastric juice varied from 0.42 per cent 



to 0.47 per cent. 



Series I. 



0.5 gr. lead arsenate ] 



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



25 cc. distilled water J 



In Solution. 



* Carlson and Woelfel, Am. Jour, of Publ. Health, 1913, p. 755; Bull. U. S. 

 Bureau of Labor Statistics, 1914, No. 141, p. 82. 



t Carlson, Am. Jour, of Physiol., 1912, XXXI, p. 151. 



