1322 
Physiology. — “The decoloration of fuchsin-solutions by amor- 
phous carbon.” By Dr. A. B. Droocieever Fortorn. (Commu- 
nicated by Prof. Dr. J. Boeke). 
Pulverized amorphous carbon has the faculty of decoloring solu- 
tions in water of several dyes, and the general explanation of 
this phenomenon is to be found in the fact that these pigments are 
absorbed by the carbon. 
Freunpiicu and Losmv (Zeitschrift für physikalische Chemie, Bd. 59, 
1907) discovered, that for Crystallviolett and Neufuchsin of the 
Höchster Farbwerke another explanation must be given. These two 
dyes are chlorides. If their solution in water is brought into 
contact with carbon, then the solution decolors. The dyes are how- 
ever not absorbed as such, but they are decomposed into hydrochloric 
acid and color-base. The color-base is absorbed by the carbon, 
presumably in the form of a polymerisation product, which by means 
of aleohol can again be removed from the carbon. The hydrochloric 
acid remains behind in the fluid, and can be shown in the filtrate 
of the solution that has been decolored by carbon by the opacity 
that occurs in it with silver-nitrate, and its acid reaction upon 
litmus. 
In 1909 (Zeitschr. £. Physik. Chemie, Bd. 67) Freunpiicn and NEUMANN 
wrote again about the absorption of Neufuchsin by carbon and 
corrected some inaccuracies in their former paper a.o. by remarking 
that the decolored filtrate of Neufuchsin does not react acidly 
upon litmus. They proved that over 33°/, of the chlorine occur- 
ring in the Neufuchsin remains behind in the filtrate decolored by 
carbon. They could not indicate with certainty the kation belonging 
to this anion Cl, but they are of opinion that these are partly H-ions, 
partly other ions resulting from inevitable contaminations of the carbon. 
According to them the thing absorbed by carbon from the Neufuchsin- 
solution may still be the color-base, but more probably it is a color- 
salt formed with contaminations of the carbon. 
When repeating these experiments with “Crystallviolett”” no devia- 
tions were found, but with ““Neufuchsin” I observed a phenomenon 
being not in accordance with the view entertained by FREUNDLICH 
and his cooperators about the decoloration of solutions of this dye 
by carbon. This phenomenon consists in the fact, that a watery 
solution of */,,,°/, Neufuchsin decolored by carbon and filtrated from 
the carbon resumes its color for a great deal when it has been 
standing for a considerable time. 
Not only Neufuchsin, but likewise the “fuchsine” of Kirp, Fuchsin 
