86 
the oil film, but to the water creeping out between the oil and the glass. 
This may be tested by placing two similar glass vessels on the pans of a 
sensitive balance, pouring some water in one and covering it with a layer 
of oil, and pouring in the other oil only to the same depth. After counter- 
balancing and closing the balance case very tightly to prevent air cur- 
rents, the arms may be kept counterbalanced by suitable riders, and it will 
be found that the evaporation of the water takes place with sufficient 
rapidity to be measured in a short time. But if the water be contained 
in a watch-glass placed in the bottom of the glass vessel and entirely cov- 
ered and surrounded by oil, no evaporation will be discovered. 
To indicate the rate at which water can thus creep between oil and 
glass, it may be stated that when the glass vessel is 9 cm. in diameter 
and the layer of oil as much as % em. thick, the evaporation takes place 
at the rate of nearly a milligram per hour. 
A Nore oN TEMPERATURE COEFFICIENT OF ELECTRICAL CONDUCTIVITY OF 
ELECTROLYTES. By ARTHUR KENDRICK. 
[Abstract.] 
This paper was a preliminary note of work begun to determine the tempera- 
ture coefficient of conductivity of various electrolytes of varying concentrations, 
The two plates give the curve of resistance and molecular conductivity in the 
case of a ;%, normal KCl aqueous solution and an approximately ;} 5 normal 
KCl aqueous solution, between 0° C and about 50°. The figures 0.100 and 0.200 
mark the ordinates of the molecular conductivity curves. The resistances in 
each case are the actual, corrected resistances for the cell used, and the molecu- 
lar conductivity is the resistance, taken from the curve divided by 725 and 735 
respectively, the concentration values. The broken straight lines are drawn to 
make noticeable the curvature. 
