294, ON THE CALCULATION OF THE CONDUCTIVITY OF 
volume of the solution to be analysed. ‘The following results 
will show with what accuracy such analyses could be carried 
out 
(1.) K,SO, in 5ee. of solution = 0.2174 gram. 
Gy ie “ Ceti ~ 
(3.) s i : == 0521100 aaa 
Mean. = 02177, e4 
(1.) Na,SO, in sce. of solution = 0.2365 “ 
(2.) i : : = 0.2369 “ 
(3.) sc “cc “ — 0.2370 c 
Mean = 0.2568 SS 
It would seem that the result might be in error by about 
0.14 per cent. 
In the case of the Potassium Sulphate, standard solutions 
were made up from weighed quantities of the salt, which had 
been dried to constant weight in an air bath. 
Preparation of the Mixtures. 
For convenience in calculating, the mixtures were made up 
of equal volumes of the constituent solutions. All mixtures 
were prepared at a temperature of 18°C, the constituent solu- 
tions being kept, for about 20 minutes previously to mixing, ina 
water bath, the temperature of which was kept as near 18°C as 
possible, by means of a thermostat. A 50 ¢.c. pipette was used to 
measure out the volumes; the same pipette being used for both 
solutions, and care being taken to use the pipette in the same 
manner in both cases. During outflow, the point of the pipette 
was allowed to rest against the side of the vessel, and when 
outflow had ceased it was slightly blown into without removing 
the point. 
_ All pipettes used were calibrated by weighing the water they 
delivered. None were used in the experiments, in which the 
time of outflow was less than 40 seconds. 
