172 RELATION OF THEOBROMINE TO BILE AND URINE. 



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 contained in 0'6 parts 

 of caffeine ; or S^ths grains of caffeine 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 caffeine, still, if it contribute in 

 point of fact to the formation of bile, the action, even 

 of such a quantity, cannot be looked upon as a nullity. 

 Neither can it be denied, that, in the case of an excess 

 of non-azotized food and a deficiency of motion, which 

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

 sues, and thus to yield the nitrogenized product which 

 enters into the composition of the bile ; that in such 

 a condition, the health may be benefited by the use 

 of compounds which are capable of supplying the place 

 of the nitrogenized product produced in the healthy 

 state of the body, and essential to the production of an 

 important element of respiration. In a chemical sense, 

 and it is this alone which the preceding remarks are 

 intended to show, caffeine or theine, asparagine, and 

 theobromine, are, in virtue of their composition, better 

 adapted to this purpose, than all other nitrogenized 

 vegetable principles. The action of these substances, 

 in ordinary circumstances, is not obvious, but it un- 

 questionably exists. 



88. With respect to the action of the other nitro- 



