Dr. A. L. Gillespie. Chemistry of the Contents of the 



diminution of the acidity throughout the tract, while calomel was 

 followed by a marked fall in the acidity values obtained from the 

 contents of every section, but especially of the small intestine. 

 Guaiacol carbonate and benzosol increased the acidity of the contents 

 of the ileum in the dog with the fistula. 



2. Acidity after Evaporation at 100° C. and Acidity driven off. — The 

 acidity remaining after drying the fluids at 100° C. was least in 

 the contents of the stomach, most in those of the duodenum when 

 the mean figures for all the observations were analysed. With 

 the exception of the stomach and large intestine the acidities, after 

 evaporation, exceeded those of the original samples. That is to say, 

 more alkali was driven off than acid. This in all probability was due 

 to the breaking up of ammonium lactate by heat and the volatilisation 

 of the ammonia. In all cases the discrepancy between the acidity 

 values obtained with phenol-phthalein and those with litmus varied 

 directly with the difference between the values before and after evapo- 

 ration. If the acidity was less in amount after evaporation than before, 

 the results as shown by the two indicators coincided; if greater, the 

 value as shown by litmus was less than that arrived at by the use 

 of phenol-phthalein. 



This increase of acidity after drying was least after food containing 

 much proteid material. After hydrochloric acid it was marked, and 

 after sodium carbonate very slight. The administration of salol was 

 followed by the presence of free acid throughout the tract, that of 

 calomel by an excess of volatile alkali over volatile acid. Of the 

 other antiseptics tested, creasote acted in a similar manner to calomel 

 but to a less extent, guaiacol and benzosol like salol. 



The Acid Factors Present. 



In the stomach the acidity was due to hydrochloric acid, either 

 free or combined with proteids, and to a small extent to acid salts. 

 In the duodenum the acidity was caused to a great extent by the 

 presence of hydrochloric acid combined with proteids expelled from 

 the stomach, but also to organic acids, such as acetic and lactic acids. 

 In the lower sections of the tract these organic acids were present 

 along with acid salts, and smaller quantities of other acids belonging 

 to the same series. 



Chlorine. — The chlorine contained in the intestinal contents was 

 separated into total chlorine, chlorine driven off by evaporation at 

 100° C. and chlorine not so volatilised, and which was further sepa- 

 rated into a part burnt off at a low red heat, and a part remaining 

 after incineration. 



The total proportion of chlorine in the different sections showed a 

 slight decrease from the stomach down to the upper half of the ileum, 



