454 
had actually to be modified so as to agree with the figures obtained. 
The question now arises whether this is really justified. 
Is the compliance with this formula really such a certain criterion 
for the presence of a surface condensation, or can we meet with a 
similar relation in the distribution of a dyestuff over two non- 
miscible liquids? 
Again, are the other properties of the dyed fibre in harmony with 
the adsorption theory ¥ Is the colouring matter really present at the 
surface only or must we assume that it has penetrated also in the 
interior of the same ? 
We will consider these questions successively. 
How is the dyestuff distributed in the fibre > 
Some years ago this question was fully discussed by Hugo 
FiscHER’), who has most strongly protested against the implicit belief 
in internal surfaces in colloids. He calls attention to the fact that 
with starch granules, for instance, the colouration is perfectly homo- 
geneous and argues in detail and on several grounds that the assump- 
tion that we are dealing with an adsorption is very improbable. He 
points out that the appearance of the coloured granule as well as the 
progressive change of the colouring process with a slowly acting dye 
stuff such as congo-red makes altogether the impression that this colou- 
ration is a phenomenon of solution and not a surface condensation. 
Supa *) in his investigations on the dye absorption of starch granules, 
also states that they are coloured quite homogeneously. The fact that 
when a dyestuff in the solid condition has a colour different to that 
of its solution, the fibre always presents the colour of the latter and 
not that of the former *) also shows that the dyestuff is present ina 
condition which corresponds with solution. 
In the case of several other phenomena which have been described 
as adsorptions, a doubt now begins to arise whether this view is 
really quite correct. VAN BEMMELEN *) has already pointed out that 
with the gels the line between ad- and adsorption is difficult to draw. 
Davis ®) found that the amount of iodine taken up by carbon increases 
with the time of action. The iodine diffuses slowly towards the 
interior of the carbon. Mc Barn ®) noticed the same in the absorption 
1) Z. f. physik. Chem. 63, 480 (1908). 
*) Sitzungsber. der K. Akad. d. Wiss. Wien 113 IIs, 725 (1904). 
5) O. N. Warr, lc. 
4) Z. f. Anorg. Chem. 23, 321 (1900). 
5) Journ Chem. Soc. 91, 1666 (1907). 
6) Z. f. physik. Chem. 68, 471 (1909). 
