228 BIO-CHEMICAL JOURNAL 







8. At low temperatures equilibrium is attained very slowly, at 

 room temperature at least 24 hours being required. 



9. The adsorption-compound of gelatin and inorganic electro- 

 lytes is also dissociated as the temperature rises. 



10. Raising the temperature rapidly to 100 tends to fix congo- 

 red in paper so that it is afterwards extracted by water with considerable 

 slowness. 



11. No evidence was obtained of any production of heat in 

 adsorption. 



12. The reaction between congo-red and cellulose is reversible, 

 as is also that between gelatin and electrolytes. 



13. Dyes forming colloidal solutions are extremely sensitive to 

 electrolytes in regard to their adsorption. The effect seems to be 

 proportional to the degree of their colloidal nature or size of colloid 

 particles. 



14. The action of electrolytes may be expressed as follows : In 

 the case of electro-negative dyes, like congo-red, kations facilitate 

 adsorption, anions depress it. In the case of electro-positive dyes like 

 toluidin-blue kations depress, anions facilitate. But in both cases the 

 effect of anions is very small compared to that of kations. 



15. The effect of bivalent kations is considerably greater than 

 twice that of univalent kations. 



1 6. Salts of the heavy metals which form positively charged 

 colloidal hydroxides in solution have a very powerful effect in pro- 

 moting adsorption of electro-negative dyes. 



17. There is evidence of the carrying-down with the adsorbed 

 dye of the facilitating ion. 



1 8. The presence of a stable colloid, like gelatin, protects congo- 

 red from the action of electrolytes. A negative charge seems necessary 

 for this action, since egg-albumin, although exercising a similar action 

 in alkaline solution, had the opposite effect in acid solution. 



19. The explanation of the action of electrolytes, as well as that 

 of other electrically-charged colloids is to be found in the negative 

 charge of non-conductors, like paper, when immersed in water. 

 (Quincke). 



