CHEMICAL PHYSIOLOGY. 15 



takes a main part. In the dog this hydrochloric acid 

 is so strong that the hardest bones are absolutely 

 dissolved. In man such a solution of bones cannot 

 easily take place, but they are certainly corroded 

 when introduced into the stomach. The acid which 

 dissolves them in the dog is hydrochloric acid only ; 

 in man it is probably a mixture of hydrochloric and 

 lactic acid. But although we find in the economy 

 chlorides everywhere, and lactates constantly in the 

 chyle, yet we do not meet with these acids in the free 

 state. We are therefore obliged to assume that in the 

 walls of the stomach a chemical process is constantly 

 taking place by which hydrochloric and lactic acids 

 are formed. This process is very simple, consisting 

 in the separation of the chlorine from sodium chloride 

 (or common salt), and the combination with it of a 

 certain quantity of hydrogen derived from the water. 

 What takes place in the glands of the stomach may 

 therefore be stated to be a splitting-up of water and 

 sodium chloride, and a cross combination of the 

 elements to hydrochloric acid on the one side and 

 sodium hydroxyde on the other. 



H 2 + NaCl = HOI + NaHO 



-\ f -^ ( -^ f ^ 



Water. Common Salt. Hydrochloric acid. Sod. hydroxyde. 



The lactic acid is produced from lactates in a similar 

 manner, and in the formula of its formation the 

 place of chlorine in the foregoing formula would be 

 occupied by the formula C 3 H 5 O 3 . This is simple 

 and certain. But we find in the body no caustic soda, 



