122 
PROFESSOR R. THBELFALL AND MR. .1. H. D. BREARLEY 
water getting on the film, the second attempt succeeded The sulphur was heated to 
a temperature of about to 250° C., and kept there for fifteen minutes ; the cooling was 
effected as rapidly as possible by water, consistently with not allowing any water to 
touch the sulphur. Some portions of the sulphur were cooled more rapidly than 
others, and consequently the percentage of insoluble sulphur present varied in samples 
taken from different parts of the dish. The film itself probably contained about 
5'2 per cent, of insoluble sulphur, but this estimate is based on analysis of sulphur cut 
away from the sides of the plates close to the film. The film itself was heated in the 
course of the experimental work, which rendered any conclusion from the analysis in 
its final state inapplicable. 
The melting-point of the sulphur, after it had been between the plates as the 
subject of experiment, was from 119*31° to 119'86° C. 
The ai'ea of the film (corrected for bubbles, &c.) was 155*845 sq. centims. ; the 
thickness of the film, by spherometer, was *02718 centim. 
As the specific inductive capacity appeared very different in this case from the values 
found previously for soluble sulphur, and as the thickness of the film is the most critical 
measurement in determining the value, we will give the means of four groups of ten 
settings, each on pieces taken from different parts of the film from which the thickness 
was deduced. They are 
Setting. 
’ 
Thickness in inches. 
(1) -336764 
•009947 
(2) -334774 
•011937 
(3) -3362U 
•010500 
(4) -336190 
•010521 
Mean, *335985 inch. 
Ten settings on glass. Mean, *346711. 
Difference, *010726 inch = *02718 centim. 
We consider that the greatest possible error of any group of settings cannot amount 
to more than 4 per cent., or the film is clearly not quite regular. 
A measurement made by focussing with a Zeiss microscope gave about *03 centim., 
but it is only of value as a rough check. It will be safe to consider the mean 
thickness as correct, within, say, 10 per cent., at least. 
The sulphur (as soon as the plates were sufficiently cooled by placing the outer 
dish in water and putting wet filter paper on the upper plate) was set up in the oil 
bath with drying material. A rough test at a temperature of 22*8° C., voltage 265*3, 
made with the old galvanometer, gave— 
Specific resistance, 4*2 X 10 2 - C.G.S, 
