SOURCE OF THE ACIDITY OF THE GASTRIC JUICE. 239 



of the process. In again distilling the gastric juice, it was 

 found that the product was neutral, presenting no precipitate 

 with the nitrate of silver, until about four-fifths of the fluid 

 had passed over ; that afterward, the fluid which passed over 

 was distinctly acid, but did not precipitate with the salts of 

 silver ; and " finally, only toward the last instants, when 

 there only remained a few drops of gastric juice to evaporate, 

 the acid liquid which was produced gave a marked precipi- 

 tate with the salts of silver, which was not dissolved by con- 

 centrated nitric acid." ' It was found that the addition to 

 the gastric juice of a small quantity of oxalic acid produced 

 a marked opacity due to the formation of the insoluble oxa- 

 late of lime, while an equal quantity of the same reagent 

 produced no opacity in water containing a proportion of two 

 thousandths of hydrochloric acid, to which chloride of cal- 

 cium had been added. From this experiment, Bernard con- 

 cluded that the hydrochloric acid in the gastric juice exists 

 in the condition of a chloride, and not in a free state. 



Prof. F. Gr. Smith, who had an opportunity of examining 

 the gastric juice from St Martin, in 1856, took the fluid from 

 the stomach after two ounces of dry bread had been chewed 

 and swallowed, and subjected it to distillation. The first 

 fluid which passed over was neutral, and the residue, after 

 the temperature had been :' somewhat raised, produced a 

 slight precipitate with the nitrate of silver, which was solu- 

 ble in ammonia. In another experiment, a mixture of lactic 

 acid and chloride of sodium in solution was subjected to dis- 

 tillation, 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 attrib- 

 utes the opalescence of the products of distillation of the 



1 BERNARD, Lemons dc Physiologic Experimentale, Paris, 1856, tome ii., p. 395 ; 

 and BERNARD, VILLEFRANCHE ET BARRESWIL, Sur les Phenomenes Chimiques 

 de la Digestion (deuxjeme memoire). Comptes Rendus, Paris, 1844, tome xix., 

 p. 1284 et seq. 



