DIGESTION. 195 



taneous presence of albumin, peptones and other bodies influence the 

 reactions more or less. The reactions for lactic acid may also give 

 negative results in the presence of comparatively large quantities of 

 hydrochloric acid in the liquid to be tested. Sugar and other bodies 

 (FR. MULLER) may act with these reagents similarly to lactic acid. 



As the above-mentioned reactions for hydrochloric acid and 

 organic acids are not claimed to be sufficient in exact investigations, 

 while they may serve in many cases for clinical purposes, it will 

 suffice to refer the reader to other text-books and especially to 

 " Klinische Diagnostik innerer Krankheiten," by R. v. JAKSCH, 

 2d edition, 1889, for the performance and the relative value of 

 these tests. 



The method suggested by CAHN and v. MEHRING for the 

 detection and simultaneous quantitative estimation of hydrochloric 

 acid in the presence of lactic acid and volatile fatty acids in the 

 contents of the stomach will be here given. The chief points 

 are the following: First the volatile acids are distilled and their 

 quantity determined in the distillate by titration. The lactic acid 

 is removed from the liquid remaining in the retort by repeated 

 shaking with large quantities of ether, and after the evaporation 

 of the ether the quantity of lactic acid in the residue is deter- 

 mined by titration. The liquid which has been shaken out with 

 the ether is either directly titrated for hydrochloric acid, or, as 

 suggested by RABUTEAU, combines the hydrochloric acid with cin- 

 chonin by digestion therewith at a gentle heat until the reaction 

 is neutral. The cinchonin combination is then agitated with 

 chloroform and the chloroform evaporated, and from the amount 

 of chlorine in this residue we may calculate the quantity of pre- 

 viously-free hydrochloric acid. This somewhat expensive and 

 lengthy method is still not free from errors, and it is made useless 

 by that following. 



The method of K. MORITER and SJOQVIST depends on the fol- 

 lowing principle : When the gastric juice is evaporated to dryness 

 with barium carbonate and then calcined the organic acids burn up 

 and give insoluble barium carbonate, while the hydrochloric acid 

 forms soluble barium chloride. From the quantity of this the 

 original amount of hydrochloric acid can be calculated. 10 cc. 

 of the filtered contents of the stomach is mixed in a small platinum 

 or silver dish, by means of a clean, sharp knife-point, witli the 

 barium carbonate free from chlorides, and evaporated to dryness. 

 The residue is burnt and allowed to glow for a few minutes. The 

 cooled carbon is gently rubbed with water and completely extracted 

 with boiling water, and the filtrate (about 50 cc.) treated with an 

 equal volume of alcohol and 3-4 cc. sodium acetate solution (10.^ 

 acetic acid and 10# acetate). The amount of barium in the filtrate 

 is determined by titration with a solution of potassium bichromate, 



