THE ACID OF THE GASTRIC JUICE. 353 



the result of eighteen concordant analyses, Schmidt found that gastric 

 juice always contained more hydrochloric acid than was sufficient to 

 neutralise all the bases present, and that the excess of hydrochloric acid 

 was alone sufficient to account for the entire acidity of the gastric juice. 

 Schmidt's course of procedure was as follows : 



The total chlorides in a weighed quantity (100 grms.) of gastric juice 

 were precipitated and weighed as silver chloride in the usual fashion, by 

 adding a drop or two of nitric acid followed by slight excess of silver nitrate 

 solution. From the nitrate the excess of silver nitrate was removed by addi- 

 tion of pure hydrochloric acid, as silver chloride ; and the filtrate, containing 

 all the bases of the gastric juice, was evaporated to dry ness, ignited, and the 

 amount of each separate base in the ash determined by appropriate methods. 

 In many cases the percentage of ammonia present was also determined in a 

 different portion as ammonio-platinic chloride. 



The amount of hydrochloric acid present, combined and uncombined, was 

 found from the weight of the first silver chloride precipitate ; the weight of 

 chlorine necessary to combine with the weight of each base present was next 

 calculated, on the assumption that all of each base was actually present as 

 chloride ; and by adding all these weights of chlorine the amount of chlorine 

 (and hence hydrochloric acid) necessary to satisfy all the bases was determined. 

 This was found to be considerably less than the total chlorine present ; in fact, 

 the difference in the two amounts represented very accurately the total acidity 

 reckoned as hydrochloric acid. 



The argument underlying Schmidt's experiments cannot be gainsaid, 

 and as the experimental part of his work was confirmed by other 

 observers, 1 there remained no choice but to accept the presence of 

 hydrochloric acid in the stomach as proven. This view accordingly 

 gained ground after the publication of his results, and is now universally 

 accepted. 



Although Schmidt's experiments demonstrate that there is an excess 

 of hydrochloric acid in gastric juice, uncombined with inorganic bases, they 

 do not show that this excess of acid is entirely uncombined. It is 

 certain that if the excess of acid is in chemical combination with any- 

 thing, the compound so formed is a very unstable one ; this is shown by 

 the ease with which the acid combines with fixed alkalies, and by the 

 persistence of the acid reaction in spite of the combination. Still there 

 are clear grounds for believing that the hydrochloric acid is in most 

 cases combined loosely with some other body, most probably albumose 

 or peptone, which are always present in traces in gastric juice. These 

 reasons are as follows : 



1. Organic acids do not dissolve calcium oxalate, but a solution of 

 hydrochloric acid in water, containing one part of acid in a thousand 

 parts of water, does dissolve this compound. Now gastric juice does not 

 dissolve calcium oxalate, from which Bernard and Barreswil 2 argued that the 

 acidity of gastric juice is not due to hydrochloric acid. This difference in 

 action on calcium oxalate of (a) a solution of hydrochloric acid in water, and 

 (b) gastric juice, is, however, probably due to the presence of albumoses and 

 peptones, which form a loose combination with the acid, of sufficient stability 

 to prevent it from acting on calcium oxalate. 



1 Cb. Richet, " Le sue gastrique chez 1'homrae et les animanx," Paris, 1878, p. 32; 

 Maly, Ann. d. Chem., Leipzig, 1874, Bd. clxxiii. S. 227. 



2 01. Bernard, "Lecons de pliysiol. exper.," 1856, tome ii. p. 395. 



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