of GRrÜBLER and Magentaroth of Grisirr, all very similar if not 
identical dyes, behave in the same manner. 
This phenomenon is most easily, and in the shortest time observed, 
when so little carbon is added to the fuchsin-solution, that the color 
does not totally disappear, but a light-pink tinge remains. To control 
the change of the color a fuchsin-solution can be used that has been 
so far diluted, that, to the eye, it corresponds with the nearly deco- 
lored solution, It will be seen that after the filtrage of the carbon, 
for which operation I used filters of ScnrricHeR and ScnüLr, the 
color of the fluid becomes very distinctly deeper. That, after all, 
the carbon had really acted absorbingly, is proved by the deeply 
staining of aethylaleohol 96°/,, if the filtrated carbon is thrown into 
it. If we take carbon to an excess, it may easily occur, that the 
color is not seen returning in the decolored solution, presumably 
because the concentration of the newly formed dye is insufficient. 
The carbon originally used by me was gross-grained char-coal, 
which had not been carefully purified. Consequently the phenomenon 
could be attributed also to contaminations of the carbon. Therefore 
1 purified the carbon according to the method likewise applied 
by FreUNDprICH and Losrv by boiling it three times with 25°/, HCI 
and washing it with distilled water. Even after very long washing 
all the hydrochloric acid bad not yet been removed, and carbon used 
in this condition prevented the return of the color of the decolored 
fuchsin. But by adding ammonia to the carbon to which hydrochloric 
acid had been applied, and after washing it again, I could obtain 
carbon, the extract of which with distilled water contained no longer 
a vestige of chlorine. Only this carbon could be considered applic- 
able to my purpose and with this carbon purified by me the pheno- 
menon was regularly observed. 
The fact that no heterogeneous substances could be the cause of the 
return of the color, was further confirmed by what follows. I obtai- 
ned some samples of carbon from the ,,Kkon. Pharmaceutische Handels- 
vereeniging” Amsterdam. If one washes one of these Carbo animal. 
depur. humida with distilled water, the filtrate reacts strongly acidly 
and it contains much chlorine. When this carbon was applied the pheno- 
menon did not occur. Neither when Carbo sanguinis was used, the 
watery extract of which contained likewise chlorine but was alkaline. 
On the contrary the extract with water of Carbo ligni tiliae pulvis 
B. 50 as preseribed in the Dutch Pharmacopy Ed. IV was neutral, and 
no precipitation with silver-nitrate could be obtained. This carbon, 
which consequently can be regarded as sufficiently pure for my 
purpose admits the return of the color in an almost decolored 
