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 filtrate the excess of silver nitrate was removed by addi- 
tion of pure hydrochloric acid, as silver chloride ; and the nitrate, containing 
all the bases of the gastric juice, was evaporated to dryness, 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. wncomMned with irwrganic 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 alburnose 
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 - 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 Ch. Riehet, " Le sue gastrique chez l'homme et les animaux," Paris, 1878, p. 32; 
Maly, Ann. d. Chevu, Leipzig, 1874, Bd. clxxiii. S. 227. 
- CI. Bernard, " Lecons de physiol. exper. ," 1856, tome ii. p. 395. 
VOL. I.- — 23 
