“491 
If for the dye salt in the aqueous solution, we take it for granted 
that there is practically a complete dissociation, the concentration of 
the dye in the aqueous. layer C,, may be considered as equal to 
eg. If now we call the division coefficients for the molecules BOH 
and BS k, and &, we obtain: 
Ca = k, BOM + k, CBZ = K, Ch ae Ha C 
w 
The first term will be of influence particularly with small con- 
centrations; the second will apply more in the case of increased 
concentrations. 
On applying the adsorption formula, ce will, therefore, increase 
n 
with the rise of the concentration. It will start with a value <1 
then become — 1 and may subsequently rise to above 1. The line 
indicating the dependence of the concentration in the alcohol layer 
on that in the aqueous layer will at first turn its concave side down- 
wards, then exhibit a point of inflexion and finally turn its concave 
side in an upward direction. 
l 
A similar variation of — has indeed been observed with a great 
n 
many dyestuffs even though with most of them no higher values than 
1 were obtained. Only with “patent blue” this value was exceeded 
1 
and — rose to 1.3. 
N 
In agreement therewith it also appears that in the case of basic 
dyestuffs, the transition into the alcohol layer is promoted by addition 
of a base and in the case of acid dyestuffs by addition of an acid and 
in such a manner that finally everything passes into the alcohol 
layer (see Table 20). 
Reversely, however, by adding acid to a basic dyestuff, or a base 
to an acid dyestuff, the transition thereof into the alcohol layer is not 
diminished. Frequently, this even causes an increase in the concen- 
tration of the alcohol layer. 
This may be partly explained by the diminution in the hydrolysis, 
and the increase in the concentration of the non-dissociated salts 
caused thereby. From the changes in colour on increasing the 
concentration of the acid added, it seems, however, that the reactions 
are often much more complicated. 
Let us take as an example crystal violet. This is a basic 
dyestuff. Formula (CH), N .C,H,}, C = GEEL = iN (GEEN Chee ine oa 
neutral or faintly alkaline solution the colour is violet. On addi- 
tion of acid the colour turns blue, then green and with still 
