1242 
Whereas the two first determinations were easily made, we met 
in the third with a serions difficulty, which made us refrain from 
further experiments above 35°.2. The solution point of the last 
distillate lies namely at 37°.2, so on the almost horizontal part 
of the solubility curve. Thereby, the determination of the concen- 
tration in this manner becomes inexact, which would become still 
worse at the higher temperatures. We have checked it for this 
distillate by adding a weighed quantity of carbon disulphide, altering 
thereby the composition and the solution point so as to bring them 
on to a part of the solubility curve, which is more easily deter- 
mined. No important difference was found. ; 
The experiments carried out show, however, clearly, that this 
system does not afford a plain proof of the theory. Although we 
see that the vapour line after extrapolation cuts the solubility curve 
at 32 molproc., whilst the critical point lies at 36°/,, the tempera- 
tures of the intersection point and the critical point cannot be 
distinguished. The course of the curves being so unfavourable for 
our purpose, we decided to take no more experiments with this 
system. Our result is remarkable in this point: although the thegry 
proves, that the vapour branch does not leave the region of limited 
miscibility in the critical point, the opinion previously expressed 
that this had to be the case, is not very far from the truth. 
Inorg. Chem. Laboratory 
University of Amsterdam. 
Experimental Psychology. “— Jntercomparison of some results 
obtained in the Investigation of Memory by the Natural and 
the Experimental Learning- Method’. By Dr. F. Rorts. (Com- 
municated by Prof. C. WINKLER). 
(Communicated in the meeting of March 31, 1917.) 
In the investigation of memory psychologists have always had 
recourse to learning-experiments, with the purpose to ascertain, under 
definite experimental conditions, the retentive capacity of the memory 
witb regard to the material impressed upon it. Whatever method 
was employed (the learning-, or the saving- or the hitting-, or the 
helping-method) the imprinting occurred invariably in the same 
way. The material to be learned, by preference meaningless, was 
presented to the observer at a certain rate of succession, and more 
or less frequently, according to the object in view. Psychologists did 
not always take into account the learning-method peculiar to every 
