240 DIGESTION. 



gastric juice, when treated with the nitrate of silver. 1 These 

 experiments are of great interest in so far as they confirm 

 the observations of Bernard, Villefranche, and Barreswil on 

 the gastric juice of the dog. 



The experiments of Lehniann on this point are even more 

 conclusive. He found that pure gastric juice, when evapo- 

 rated in vacuo, develops hydrochloric acid; but he also 

 found that chloride of calcium is decomposed during evapo- 

 ration 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, Yillefranche, and Barreswil. 2 



These observations explain perfectly the presence of 

 hydrochloric acid in liquids obtained by distillation, of the 

 gastric juice, without supposing that this acid, in a free state, 

 is one of its normal constituents. But this is not the only 

 ground on which the opinion that the hydrochloric is the 

 free acid of the gastric juice is based. Physiologists of the 

 present day who hold to this view rely chiefly . on the re- 

 cent examinations of the gastric juice of the dog by Bidder 

 and Schmidt. It remains now to see whether the observa- 

 tions of Schmidt, which apparently demonstrate the exist- 

 ence of a proportion of chlorine not to be accounted for ex- 

 cept under the supposition that it exists in the form of free 

 hydrochloric acid, are conclusive, when opposed to the facts 

 which are supposed to be inconsistent with the existence of 

 free hydrochloric acid in the gastric secretion. The method 

 employed by Bidder and Schmidt is, in brief, the following : s 



The juice was taken from dogs that had been fasting for 

 from eighteen to twenty hours, the food having previously 

 been either animal or vegetable, the gastric juice in both 

 cases being identical. To prevent the admixture of saliva, 



1 F. G. SMITH, Experiences sur la Digestion. Journal de la Physiologie, Paris, 

 >1858, tome i., p. 149 et seq. 



2 LEHMANN, Physiological Chemistry, Philadelphia, 1855, vol. i., p. 93. 



8 BIDDER UND SCHMIDT, Die Verdauungssafte, Leipzig, 1852, S. 44 et seq. 



