of the University of Pennsylvania. 35 



in no wise retarded, the variation from the nor- 

 mal, if any, being toward an acceleration of this 

 process. 



It is evident, therefore, that, other things being 

 equal, the appropriate time for the exhibition of 

 this drug is immediately upon the cessation of sali- 

 vary digestion within the stomach, or, in other 

 words, upon the first formation of free acid within 

 that viscus. 



Recent studies 1 have shown that the acidity of 

 the gastric contents, found even in quite early stages 

 of digestion, is not due to the presence of free acid ; 

 and the ingenious observations of Von den Velden 2 

 go far toward proving that the development of free 

 acid within the stomach does not occur until from 

 forty -five minutes to an hour after breakfast, and 

 from one to two hours after dinner. These results 

 were obtained chiefly by the use of methyanilin violet 

 and tropseolin, bodies delicately responsive, by color- 

 change, to the presence of free acid. There is little 

 doubt in my mind that hydrochloric acid is devel- 

 oped in the stomach at an earlier period than that 



1 Deutsch. Archiv Klin. Med., xxiii. 369. See also 

 Jahresb. ii. d. Fortschr. d. Thier-Chemie, 1880, p. 302, and 

 Danilewsky, Centralb. f. d. Med. Wiss., 1880. 



2 Zeitschr. f. Physio! . Chemic, iii. 205. 



