of Globe's Theory of Surface-Concentration, 525 
Experimental determination of Y : — 
'1")0 c.c. o£ -07 per cent, solution were shaken with oil 
and formed an emulsion. 
The Fall in concentration = '032 per cent. 
.-. Total mass adsorbed = "08 grin. 
Adsorbing surface area = '$$£&-* 
.-. r — 5'5x 10~ 6 grm. per cm. 2 
Calculated value = 1"2 x 10 -7 „ „ 
We have here a further repetition of the observed 
anomaly. 
In considering the behaviour of these dyes in relation to 
the adsorption theory, it may be admitted that despite the 
discrepancy between the observed and calculated results, 
substantive dyeing, at any rate, must bp more or less an 
adsorptive process. Possibly the actual mechanism of dyeing 
consists first in adsorption and afterwards coagulation possibly 
due to "colloidal neutralization/' There may finally be 
some degree of chemical combination, which varies from case 
to case. 
Note on Rosaniline hydrochloride and Crystal Violet. 
A saturated aqueous solution of Rosaniline hydrochloride (about 
•06 per cent.) gave a drop-number of 140 — i. e., a Tension of 43*87 
dynes cm. The" decrease in interfacial tension is less marked than in 
methyl orange or Congo red. No further experiments were carried out 
with this substance. Also Crystal Violet dye concentration 1 per cent. 
gave a drop-number 230, and hence also shows a lowering of tension. 
V. Summary. 
1. The object of the investigation has been to examine 
from an experimental standpoint Gibbs's theory of surface- 
concentration, as the chief cause of the phenomenon of 
Adsorption. By modifying Gibbs's fundamental expression 
for surface-concentration, an equation is obtained giving the 
mass of solute adsorbed per cm. 2 in terms of the concentration 
of the solution and the change in tension at the interface, 
aqueous solution — hydrocarbon oil. 
2. The material employed consisted of aqueous solutions of 
bile-salts, the solute being adsorbed at the hydrocarbon-oil 
surface. The mass adsorbed per cm. 2 oil surface was 
Phil. Mag. S. 6. Vol. 15. No. 88. April 1908. 2 N 
