ABSORPTION. 261 



that the degree of solubility of substances has not yet admitted of 

 being brought into definite relations to their chemical constitution, 

 or even to any other of their properties. Even the coefficient of 

 condensation cannot be regarded as a standard for the amount of 

 this attraction between water and a solid body ; for even in the 

 attraction which regulates the chemical combination, it is of no 

 consequence in reference to the determination of its amount ; nor 

 has any definite relation been discovered between the modulus of 

 condensation of these bodies and any one of their integral properties. 

 Even the degree of diffusion of soluble bodies does not readily 

 give the amount of attraction between the solid and the fluid; but 

 its dependence upon weight seems to be very clear from Graham's 

 investigations. Although no definite connection can be estab- 

 lished even from these three intimately allied relations between 

 water and soluble bodies, we yet learn from previous observations, 

 that certain relations, which are at all events analogous, may be 

 determined for different well-characterized groups of bodies. 

 These relations, however, acquire so much the higher signification, 

 since they are more especially reflected in the groups of substances 

 which play a considerable part in the animal body, and are thus of 

 great importance in our discrimination of the products of the meta- 

 morphosis of matter and of absorption generally. C. Schmidt 

 found that the coefficients for 10 per-cent. solutions of chloride 

 of sodium, grape-sugar, and albumen, were T505, 0'766, and 0*420. 

 Graham observed the following proportion for the diffusibility of 

 these three substances in 20 per-cent. solutions, namely, 100, 

 45-36, 5'24. The analogy is here very great, although we may 

 not be able to recognise any equal proportion in these numbers. 

 Moreover, Graham's provisional investigations show distinctly 

 enough that there is a definite relation between the diffusibility and 

 the specific weight of the diffusing fluid ; hence the coefficient of 

 condensation must have a direct relation to the diffusibility; at any 

 rate we cannot at present overlook this relation. Urea here pre- 

 sents itself as an important exception ; the coefficient of conden- 

 sation of its 10 per-cent.-solution was found by Schmidt to be less 

 than in any other substance (=0'160), while its diffusibility is, 

 according to Graham's determination, exactly equal to that of 

 chloride of sodium. 



Owing to the generally recognised and very comprehensive 

 relation existing between the capacities for diffusion and transuda- 

 tion, it will not surprise us to find that the endosmotic equivalents, 

 when calculated by Jolly's provisional method, should correspond 



