1349 
are always adsorbed much more strongly than might be surmised 
from their influence on the surface tension *). [ determined stalagmo- 
metrically the o-e figure for phenol (also given in the figure): 
although it appeared to lie between that of isobutyl and propyl 
alcohol, the influence exerted by addition of phenol is greater than 
that caused by iscbutyl alcohol, exactly as was to be expected. This 
investigation is being continued, also in connection with a direct 
investigation as to the adsorption of the substances added. 
A more extended investigation in various directions appears to 
me desirable all the more because the results may elucidate several 
other problems in the chemistry of the colloids. I will again refer 
to this matter in due course. 
Meanwhile the results obtained are interesting when taken in 
‘connection with the researches of H. Lacns and L. Micnaiiiis?), who 
found that surface-active non-electrolytes exert no influence on the 
adsorption of electrolytes: the above described investigation, however, 
makes us surmise that although these two kinds of substances should 
not be put on a par with each other without further evidence, a 
displacement takes place nevertheless. The effect of the displacement, 
however, seems to elude the direct measurement, bnt it may be 
demonstrated by measurements of the limitation values. Hence, the 
said investigators couid find a displacement effect for isoamylalcohol 
only, just the very alcohol which according to our research exerts 
the strongest power of displacement. 
Utrecht, March 1913. van ’T Horr-Laboratory. 
Microbiology. — “Potassium sulfur, and magnesium in the meta- 
bolism of Aspergillus niger.” By Dr. H. J. Waterman. (Com- 
municated by Prof. M. W. BeiJerINCK). 
In earlier investigations I have shown that the elements carbon, 
nitrogen, and fosfor occur in large quantities in young mould material, 
but that, when it grows older, a considerable portion is again excreted 
as carbonic acid, ammonia, and fosforie acid *). During the develop- 
ment the plastic aequivalent of the carbon lowers to the half; as 
to the nitrogen, there is a threefold accumulation, whereas the quan- 
tity of fosfor in a young mould layer is ten times as large as that 
1) Compare for instance I. TRAuBe, Verh. d. deutschen physik. Ges 10, 880 
(1908). In the Table on p. 901, Aniline the only aromatic compound, occupies 
a quite special position. 
*) Zeit-chr. f. Elektrochemie 17, 1 (1°11). 
3) Folia microbiologica Bd. 1 p. 422, 1912. These Proceedings 1912. 
88 
Proceedings Royal Acad. Amsterdam. Vol. XV, 
