COMPOSITION OF THE GASTRIC JUICE. 239 



was neutral, and the residue, after the temperature had been somewhat raised, produced 

 a slight precipitate with the nitrate of silver, which was soluhle in ammonia. In an- 

 other experiment, a mixture of lactic acid and chloride of sodium in solution was sub- 

 jected to distillation, and the product formed a slight precipitate with the nitrate of sil- 

 ver, which was soluble in ammonia. In another experiment, a mixture of lactic acid 

 and chloride of sodium in solution was subjected to distillation, and the product formed 

 a slight precipitate with the nitrate of silver. The precipitation, in this instance, was 

 attributed to the passage of a small quantity of chloride of sodium with the vapors, and 

 it is to this, also, that he attributes the opalescence of the products of distillation of the 

 gastric juice, when treated with the nitrate of silver. These experiments are of great 

 interest in so far as they confirm the observations of Bernard, Villefranche, and Bar- 

 reswil, on the gastric juice of the dog. 



The experiments of Lehmann are even more conclusive. He found that pure gastric 

 juice, when evaporated in vacua, develops hydrochloric acid ; but he also found that 

 chloride of calcium is decomposed during evaporation with lactic acid in vacuo and 

 attributes the generation of hydrochloric acid in the gastric juice to the decomposition 

 with this salt, and not the chloride of sodium, as was thought by Bernard, Villefranche, 

 and Barreswil. 



The addition of a small quantity of oxalic acid to gastric juice produces a precipitate 

 of the insoluble oxalate of lime, which does not take place in the presence of free hydro- 

 chloric acid, even when it exists in very minute quantity. No one has denied that this 

 reaction always takes place in the gastric juice ; but, in this fluid, is it inconsistent with 

 the presence of a small quantity of hydrochloric acid ? We have found that the addition 

 of two drops of ordinary hydrochloric acid to half a fluidounce of gastric juice does not 

 prevent the precipitation of the oxalate of lime, which, in the single observation referred 

 to, was prevented only when the quantity of acid was increased to five drops. On adding 

 oxalic acid to fresh urine, the precipitate of oxalate of lime was marked ; but, after the 

 addition of two drops of ordinary hydrochloric acid, this reaction did not take place. 

 Taken in connection with the fact that many of the ordinary chemical reactions are pre- 

 vented or modified in fluids containing organic substances, this would lead us to inquire 

 whether free hydrochloric acid may not exist in small quantity in the gastric juice, and, 

 as an exceptional phenomenon, the reaction between the oxalic acid and the soluble salts 

 of lime still take place, or whether the acid may not unite with the organic principle, 

 forming, as was suggested by Schiff, chlorohydropeptic acid. In support of this latter 

 view, it is to be remembered that Mulder has formed combinations of organic principles 

 with various of the mineral acids, such as the sulphuric and the hydrochloric. In these 

 compounds, the acid character remains, but the ordinary reactions of the acid are lost. 



With the abundant opportunities which have been presented for the chemical study 

 of the gastric juice, not only in the inferior animals but in man, and in view of the nu- 

 merous elaborate researches into the nature of this fluid by the most skilful physiological 

 chemists of the day, it is a matter of surprise that the question of the existence of free 

 hydrochloric acid, or its condition as regards combination with the organic matter, is 

 not settled. It certainly cannot now be regarded as determined beyond question. If, 

 as is supposed by Bidder and Schmidt, there be a proportion of chlorine which cannot be 

 accounted for by the quantity of ordinary bases in the gastric juice, it probably does not 

 exist as free hydrochloric acid, but it is in some way united with organic matter. 



In 1786, Macquart indicated the presence of lactic acid in the gastric juice of the calf, 

 attributing the acidity of the gastric juice of the ox and the sheep to free phosphoric 

 acid. Since then there have been numerous analyses in which this princ-ipU' has been 

 said to be found. Among those who early adopted this view, may be mentioned Che- 

 vreul, Graves, and Leuret and Lassaigne. After the analyses by Prout, in 1823, and the 

 observations of Beaumont on the fluid obtained from St. Martin, and until the publication 

 of the experiments of Bernard, Villefranche, and Barreswil, in 1844, hydrochloric acid 



