1158 
departures from the average in the strength of the North-East trade, 
it seems possible to us, to make a forecast about the sign of the 
departure from the normal of some phenomena in the Northern 
European seas. 
Whether the correlation will prove to be greater or smaller if 
longer series are at our disposition, cannot be said with any certainty 
beforehand. 
Chemistry. — “The connexion between the limit value and the 
concentration of Arsenic Trisulphide sols’. By Dr. H. R. Krurr 
and JAC. vAN DER SPEK. (Communicated by Prof. E. Conen). 
(Communicated in the meeting of February 27, 1915). 
1. When one of us‘) carried out experiments with the As,S, sol 
conjointly with C. F. van Duin, it once struck us that a sol, which 
we had diluted to half its concentration, had retained nearly the 
same limit value. The object of the investigation communicated here 
was to endeavour to get some more knowledge as to the connexion 
between the As,S, concentration and the limit value of the sol. 
2. One may preconceive an idea as to this connexion. We assume 
for the moment that the sols differ only in concentration but not in 
the size of their particles. Now the limit value y is the concentration 
at which so much of the coagulating cation is withdrawn by 
adsorption that the charge of the particles is diminished to a definite 
value differing but little from 0. Hence, the adsorbed quantity of 
cation («) per particle is characteristic of the limit value. This again 
is connected with the concentration y in cation in the solution after 
the congulation’) according to this equation: 
i 
am kyr 
so that y is, therefore, also characteristic of the limit value but 
independent of the concentration of the sol. As for the limit value y 
we simply take into account the bruto-added electrolyte quantity, y 
is as a rule not independent of the concentration. 
In -the Fig. 1 and 2 are represented schematically two sols in 
which the second has the double concentration of the first. When 
properly choosing the units we have in Fig. 1: y,=xz--4, in 
Fie. 2: y,=x-+ 2a. 
1) Kruyr and van Duin, Koll. Beih. 5, 269 (1914). 
2) For fuller details compare Kruyt, Proc. 17, 623 (1914). 
