102 
PROFESSOR R, THRELFALL AND MR. J. H. D. BREARLEY 
1891. On October 6, 1891, a film of recovered sulphur, four times distilled and 
'022 centim. thick, was got between the plates, and a long series of experiments 
commenced with it. Amongst other experiments the amount of residual charge was 
measured, and, on November 12, 1891, the film was heated up to near the melting 
point. All the results obtained were so irregular that we could not draw any con¬ 
clusions from them, and several circumstances led us to suspect that the film had 
been pierced by electric stress on October 15, with a voltage of 712. The plates were 
taken apart on January 6, 1892, when it was found that the film no longer adhered 
to the aluminium plates, and that a discharge had passed at some time or other, 
forming a lump of dark-coloured substance, and burning a hole in both aluminium 
plates. All the results obtained between October, 1891, and January, 1892, have, 
therefore, been rejected, with the exception of the following, all of which were 
afterwards confirmed, and which we had reason to think were not affected by the 
piercing of the film. 
(1.) Before the film broke down with the voltage of 712 it had been exposed to 
voltages of about from 648 to 684 volts, giving rise to a small conduction, which 
was intermittent. In the first experiment a deflexion of 58 divisions was obtained 
with the battery in one direction, and of only 20 divisions when it was reversed ; on 
reversing again, a deflexion of 68 divisions was obtained. These results are similar 
to others afterwards obtained with much smaller voltages, and are of importance as 
showing that the properties of sulphur, considered as a conductor, do not undergo 
any great qualitative change when the voltage per unit length is increased nearly to 
the breaking-down point. 
The specific resistance of the sulphur, if we take 40 divisions as the average 
deflexion, is about 6’6 X 10 32 C.G.S. 
The film contained an unknown amount of insoluble sulphur, but this resistance is 
less than any other observed by us at the same temperature (18° C.), while it is 
known that the amount of insoluble sulphur present could only have been very small 
as the film was cooled slowly. It will be shown that in general the resistance 
appears to diminish with an increased voltage, so that very possibly the small resist¬ 
ance observed in this experiment may be due to the high voltage employed, or, 
rather, to the great electric force in sulphur. 
(2.) The sulphur was not cut away from the plates in this instance, but extended 
from the upper plate to the sides of the gold dish. After the film had been broken 
down, or, rather, after the time at which we consider it had been broken down, the 
resistance, as we have said, became very irregular. In seeking for the cause of this 
we examined several possible explanations, and, amongst them, the influence of surface 
action. The surface leakage, in this case, must have occurred between the upper 
plate and the sides of the gold dish, and it was thought that the surface resistance 
could be increased temporarily by scraping the intermediate sulphur surface. This 
was done without producing any change in the apparent resistance, The following 
