OSMOSIS. 
The following instances are taken from Pfeffer: l - 
Copper Ferrocyanide Membrane. 
267 
( lONCENTRATION. 
Rise of Fluid is Measuring Tim: 
is Mm. l'KK 1 1 ■ > I K. 
Experiment I. Experiment II. 
Temp. 17°1 0. Temp. 15°*8 < . 
1 per cent, saltpetre . 
15 ,, gum-arabic 
1 ,, saltpetre + 15 per cent. 
gum-arabic 
1 per cent, saltpetre . 
.Mm. .Mm. 
6-08 5-4 
2-06 1-8 
7-90 7-0 
6-06 5-3 
Parchment Paper Membrane. 
Concentration. 
Rise of Fluid is Measuring Tube 
is Mm. Per Hour. 
Experiment I. 
Experiment II. 
1*5 per cent, calcium chloride 
2 ,, gum-arabic 
1'5 ,, calcium chloride + 2 
per cent, gum-arabic 
9-9 
1-2 
11-4 
10-3 
1-3 
11-3 
Temperature in both experiments. 17 '4 C. 
In cases, however, where the two constituents of the solution have 
a common ion, each salt diminishes the dissociation of the other, so that 
the pressure of the mixture is less than the sum of the pressures of the 
two components. 2 
Thus for a double salt — 
A 
. 
D. 
Osmotic 
Pressure. 
Sum of 
Components. 
Osmotic 
Pressure. 
Sum of 
Components. 
T V(NHJ 2 S0 4 
1-264 At. 
1-295 
¥ VAl 2 (SOJ 3 • • • 
1-265 „ 
l - 22 
T VKnS0 4 
1-29 ,, 
1-40 
1 V(NHJ,ALSOJ,24A.i 
2-37 ,, 
2-53 
1-98 
2-515 
AK 2 Al 2 (SOJ 4 24Ar| 
2'39 ,, 
2-56 
1-96 
2-62 
1 Pfeffer, loc. tit., p. 68. 
3 From Adie, Journ. Ohem. Soc, London. 1891, vol. lix. p. 344. 
