AND THEOBROMINE TO BILE AND URINE. 181 



or 



1 at. theobromine C J8 N 6 H 10 O 4 ^ C 



8 at. water H 8 O 8 U 2 &t ' taurine 



14 at. oxygen oj [ l at ' Uric acid 



C 18 N 6 H 18 26 C 18 N 6 H 18 2 



88. To see how the action of caffeine, asparagine, 

 theobromine, &c., may be explained, we must call 

 to mind that the chief constituent of the bile 

 contains only 3'8 per cent, of nitrogen, of which 

 only the half, or 1/9 per cent., belongs to the tau- 

 rine. 



Bile contains, in its natural state, water and solid 

 matter, in the proportion of 90 parts by weight of the 

 former to 10 of the latter. If we suppose these 10 

 parts by weight of solid matter to be choleic acid, 

 with 3'87 per cent, of nitrogen, then 100 parts of 

 fresh bile will contain 0*171 parts of nitrogen in 

 the shape of taurine. Now this quantity is con- 

 tained in 0*6 parts of caffeine ; or 2-fyths grains of caf- 

 feine can give to an ounce of bile the nitrogen it 

 contains in the form of taurine. If an infusion of 

 tea contain no more than the ^th of a grain of caf- 

 feine, still, if it contribute in point of fact to the 

 formation of bile, the action, even of such a quan- 

 tity, cannot be looked upon as a nullity. Neither 

 can it be denied that in the case of an excess of 

 non-azotised food and a deficiency of motion, which 

 is required to cause the change of matter in the tis- 

 sues, and thus to yield the nitrogenised product 

 which enters into the composition of the bile ; that 



