ON THE ELECTRICAL PROPERTIES OF PULE SULPHUR, 
123 
No marked difference was observed between the conductivity when the battery 
was first on, and five minutes afterwards, but the resistance slowly increased as 
usual. 
The capacity was measured by the De Sauty method, using the small storage 
cells with a voltage of 205'3 volts. The instantaneous balance was reached with 
between 1070 and 1072 out in one arm, and 100.000 out in the other. The resulting 
capacity was ’002142 X 10 -15 C.G.S. Applying a correction of — 2 per cent, for the 
key and -f- 1 per cent, for the value of the standard, or, in all, — 1 per cent., this 
becomes ’00212, say. The corrected value of the specific inductive capacity is 
4T814. We can only explain this large value by supposing that the film measure¬ 
ment is at fault, or that the specific inductive capacity of mixed sulphur is really 
high. The film measurements are given in order to allow the reader to form his own 
opinion on this point. 
The sulphur was kept in the drying box for 24 hours at a temperature of about 
22° C. The specific resistance = 5’05 X 10 24 C.G.S. 
So it has not changed much by continued drying ; the battery was not reversed, 
and the mean deflection was 57 divisions. After the battery had been applied for 
about one hour the double deflection fell to 17 divisions. The voltage was 264 volts. 
The current having become fairly constant, it was thought advisable to investigate 
whether the deflection was due to surface conductivity. From previous experiments 
it is known that the sulphur surface conductivity, after a day’s drying, will not make 
the apparent specific resistance less than of the order of 10 27 C.G.S., but this was with 
highly soluble sulphur. It is not likely that the admixture of insoluble sulphur will 
increase the surface conductivity, but it is possible that it may do so, and in that case 
we should expect that exposure to damp air would reduce the apparent resistance. 
The lid was therefore taken off the thermostat, and the plates freely exposed to the 
air for ten minutes. Dry bulb, 72° F. ; wet bulb, 65'5° F. No change having been 
detected, a current of air which had been passed through a reversed wash-bottle with 
the water at 50° C., was allowed to play for about five minutes on the sulphur 
between the upper plate and the dish. The deflexion or reversal of the galvanometer 
remained precisely the same as before. The conclusion is that the conductivity is 
probably almost wholly due to the sulphur, and that the latter is not affected by 
damp air to anything like the same extent as glass is. This is confirmed by some 
observations to be described, in which, when the sulphur plates are heated in a closed 
box with drying material to 50° C., the conductivity is increased, whereas, if it were 
due to surface action, the opposite effect would be expected. The sensitiveness of the 
galvanometer (new), when these experiments were made, was about 5’2 X 10 -12 
ampere per micrometer scale division, and the period was eleven seconds. This 
(November 10, 1892) was the steadiest day we ever had, the galvanometer could 
have been read to ’2 division perfectly, had it been necessary. The next day was 
almost equally steady, and w 7 e had a good example of the effect of variable con- 
