32 THE SECRETIONS: 



sence of phosphoric acid. On saturating the acid with lime and 

 oxide of zinc, and filtering the solution, the neutral nitrate 

 contains both zinc and lime, therefore phosphoric acid is not 

 the only free acid in the juice. What is the acid combined 

 with the zinc and lime in the filtered solution? It is one 

 which, as we have seen, passes over at the end of the distillation, 

 and does not precipitate salts of silver. These characters be- 

 long to lactic acid. On distilling water slightly acidulated with 

 lactic acid, a small quantity of chloride of sodium being added, 

 we obtain a fluid analogous to gastric juice; first, pure water 

 passes over, then an acid which does not precipitate salts of 

 silver, and the last drops carry over hydrochloric acid. So that 

 it is evident that the presence of hydrochloric acid in the last 

 product of distillation of the gastric juice is owing to the de- 

 composition of the chlorides by lactic acid." 



Hydrochloric acid cannot exist in a free state in the presence 

 of a lactate, a phosphate, or an acetate. " We have observed," 

 say the authors, " in the acid of the gastric juice all the cha- 

 racters of lactic acid, as pointed out by M. Pelouze ; both give 

 soluble salts of lime, barytes, zinc, and copper, a double salt of 

 copper and lime, deeper in colour than the simple salt, and a salt of 

 lime soluble in alcohol, precipitated by ether." From the above 

 facts, MM. Bernard and Barreswil conclude that the acid re- 

 action of the gastric juice is not owing to biphosphate of lime, 

 but arises from a free acid, which is not hydrochloric or 

 acetic acid. They have always found lactic acid, with a minute 

 proportion of phosphoric acid, the latter being a product of the 

 reaction of the lactic acid on the phosphates present. In 

 their opinion, lactic acid is a constant production of the 

 stomach. They do not mean to say that the digestive powers 

 of the gastric juice are owing to lactic acid ; on the contrary, 

 they think if an acid reaction be indispensable, other acids may 

 supply its place, because among the various salts constantly in- 

 troduced into the stomach with the food, some will have their 

 acid replaced by the free lactic of the stomach, and the new 

 acid liberated may supply the place of the normal acid. 



In a more recent memoir they enter more fully into the 

 nature of the active organic matter, on the presence of which 

 they believe the digestive power of the gastric juice to depend. 

 It is precipitated and destroyed at a temperature of 190. One 



