112 LACTIC ACID NOT FORMED 



sugar by means of membrane in a state of decompo- 

 sition out of the body ; but in a normal state of 

 health, no lactic acid is formed in the stomach. 



11. The property possessed by many substances, 

 such as starch and the varieties of sugar, by contact 

 with animal substances in a state of decomposition, 

 to pass into lactic acid, has induced physiologists, 

 without further inquiry, to assume the fact of the 

 production of lactic acid during digestion ; and the 

 power which this acid has of dissolving phosphate of 

 lime has led them to ascribe to it the character of a 

 general solvent. But neither Prout nor Braconnet 

 could detect lactic acid in the gastric juice ; and even 

 Lehmann (see his "Lehrbuch der Physiologischen 

 Chemie," torn. i. p. 285) obtained from the gastric 

 juice of a cat only microscopic crystals, which he 

 took for lactate of zinc, although their chemical 

 character could not be ascertained. The presence 

 of free muriatic acid in the gastric juice, first ob- 

 served by Prout, has been confirmed by all those 

 chemists who have examined that fluid since. This 

 muriatic acid is obviously derived from common salt, 

 the soda of which plays a very decided part in the 

 conversion of fibrine and caseine into blood. 



Muriatic acid yields to no other acid in the power 

 of dissolving bone earth, and even acetic acid, in this 

 respect, is equal to lactic acid. There is conse- 

 quently no proof of the necessity of lactic acid in 

 the digestive process ; and we know with certainty, 

 that in artificial digestion it is not formed. Berze- 



