146 SODA ESSENTIAL TO THE 



The transformation of the compounds of proteine 

 present in the body is effected by means of the oxygen 

 conveyed by the arterial blood, and if the elements of 

 starch, rendered soluble in the stomach, and thus carried 

 to every part, enter into the newly formed compounds, 

 we have the chief constituents of the animal secretions 

 and excretions ; carbonic acid, the excretion of the 

 lungs, urea and carbonate of ammonia, excreted by the 

 kidneys, and choleic acid, secreted by the liver. 



Nothing, therefore, in the chemical composition of 

 those matters, which may be supposed to take a share in 

 these metamorphoses, is opposed to the supposition, that 

 a part of the carbon of the non-azotized food enters into 

 the composition of the bile. 



51. Fat, in the animal body, disappears when the 

 supply of oxygen is abundant. When that supply is 

 deficient, choleic acid may be converted into hippuric 

 acid, lithofellic acid, (37) and water. Lithofellic acid is 

 known to be the chief constituent of the bezoar stones, 

 which occur in certain herbivorous animals : 



2 at. choleic acid CN.,HO ) ( 2 at hi P- acid C 36 N 2H 16 O 10 



2 at. choleic acid C 76 N.,H 66 O 22 ) _ ( 2 at hi P- acid 



10 at. oxygen . O lrt S ) l at lith ' acid C 



_ _ ( 14 at. water . . 



C 76 N 2 H 66 32 C 76 N 2 H 66 32 



52. For the production of bile in the animal body a 

 certain quantity of soda is, in all circumstances, neces- 

 sary ; without the presence of a compound of sodium 

 no bile can be formed. In the absence of soda, the 

 metamorphosis of the tissues composed of proteine can 

 yield only fat and urea. If we suppose fat to be com- 



