637 



of basic dyes. All iiiorgaiiic t'ompounds and their ions are adsorbed 

 in nearly equal amounts from solutions of equal molecular concen- 

 tration, excepted the ions of H, OH and of the heavy metals, which 

 show an abnormally high adsorption. So the hydroxides of the alcali- 

 metals will add to the negative charge, for the OH ion is adsorbed 

 more fully than the metal-ion. The same will be caused by alcali 

 salts of poly basic acids, as the negative ion has a greater electric 

 charge than the kation ; and again the same will be the case by 

 adding salts of organic acids, because organic ions are more fully 

 adsorbed than anorganic ones. When dyeing with acid dyes, we 

 shall meet with an exactly opposite effect of electrolytes, dyeing being 

 increased by acids, by salts of bi- and trivalent kations and of 

 organic ones. . Influences, diminishing the process of dyeing, may 

 easily be inferred to the same line of thought. 



Pelet's investigations are in perfect accord with the above theory, 

 both for the adsorption of the dyes itself and for the influence of 

 dyes and electrolytes on capillary electric phenomena. 



2. W. Reindeks ^) lately published a paper in which he dreu 

 the conclusion that there remained much doubt about the connection 

 between dyeing and the phenomena of adsorption. He had made 

 investigations on the ratio in which a solution in water gave the 

 dye to another phase, which was not a solid with great develop- 

 ment of surface, but which was a liquid; the dyesolution was shaken 

 with isobutylic alcohol. First the distribution of the dye in the 

 two layers showed to be not in harmony with the disti-ibution- 

 law. In the second place he remarked in those cases, that whether 

 acid or alcali increased the process of dyeing, the transition of the 

 dye into the alcohol layer was also favoured. He came to the 

 conclusion that these facts pointed clearly to a solution theory, and 

 that it was of no use to refer to the theory of adsorption. 



The interesting question, that was brought forward again by that 

 paper, induced us to make the following investigation. Fiist of all 

 we are of opinion that for a good solution of this intricate problem 

 it is of the greatest importance to avoid all unnecessary complication : 

 therefore we shrink from drawing conclusions from experiments, 

 when alcali or acid is present together with the dye. For these 

 bodies often cause a chemical change in the molecule of the dye, 

 in which case we have to deal with a chemical phenomenon and 

 the process of dyeing simultaneously. So we have studied the 



1) Koll. Zeitschr. 13, 96 (1913). 



