326 PHYSICAL PROPERTIES 



within protein solutions is built up out of protein ions.* Such 

 a conclusion is totally out of harmony with the prevailing view 

 that ions, in solutions of electrolytes, are mutually independent 

 and physically discrete bodies, and would appear to invite a dis- 

 tinction between the mode of ionization of ordinary electrolytes 

 and that of protein salts. It is very questionable, however, 

 whether such a distinction would be valid. Many modern in- 

 vestigations point to the existence of some modification of the 

 familiar " Grotthus-chain " in solutions of electrolytes, most 

 impressive among which is possibly the fact that in watery solu- 

 tions the most rapidly-moving ions are those which, by their 

 combination, give rise to water itself, i.e., hydrogen and hydroxy!, 

 while in other solvents hydrogen and hydroxyl are not the most 

 rapidly moving, but those which, by their combination, give rise to 

 the solvent (24) (125) (25) (60). The fact that the viscosities of 

 solutions of crystalloid electrolytes have not so far revealed the 

 presence of a net-structure within them is possibly attributable to 

 the tenuity of the net and to the fineness of its framework; to 

 revert to the analogy employed above, a net of the finest and most 

 flexible silk will readily pass without appreciable resistance 

 through a tube which would offer a considerable resistance to the 

 passage of a net of coarse thread. The phenomena to which I 

 have drawn attention may quite conceivably be of very general 

 occurrence, and of greater physical magnitude in solutions of 

 proteins simply because of the greater size of the protein mole- 

 cules. In this connection the views regarding the nature of 

 ionization which have been put forward by Wm. Sutherland (118) 

 offer extremely tempting suggestions. 



The hypothesis that gelatin solutions, even those which do not 

 gelatinize, contain a structure has also been put forward by Wo. 

 Ostwald (80). The influence of added inorganic salts upon the 

 viscosity of gelatin solutions has been studied by von Schroeder 

 (loc. cit.); this observer finds that the chlorides and nitrates of 

 the alkalies diminish the viscosity of gelatin solutions while sul- 

 phates increase it. Moreover the alteration in viscosity induced 

 by the added salts does not vary continuously in a definite sense 



* Indeed, whether we assiime that the viscosity of protein solutions is due 

 to protein ions or not, it would be difficult to avoid this conclusion in the light 

 of the fact that many highly viscous solutions of caseinates are over 90 per cent 

 dissociated (Cf. Chap. X). 



