128 
PROFESSOR R. THRELFALL AND MR, J. H. D. BREAREET 
however, that the film was more quickly cooled than the sulphur round its edges, in 
which case the film probably contained upwards of 7 per cent, of insoluble sulphur. 
The colour of the sulphur in the dish was anything but satisfactory—it was 
appreciably darker than it ought to have been—especially immediately after cooling. 
Some samples were cut out with difficulty from round the plates, and on evaporation 
from platinum left an appreciable stain. 
It was thought that possibly the carbon dioxide atmosphere in which the sulphur 
was heated had led to contamination under the action of the slightly burning sulphur. 
A number of experiments were therefore made by setting fire to sulphur in partial 
carbonic acid atmospheres, but no trace of contamination could thus be brought about. 
We consider the dark colour as probably due to the action of a certain amount of 
dust which must have collected on the sulphur during the manipulations—some of 
the same sulphur having been used in a previous experiment. 
The results obtained with this film were similar to those with the last film, but 
with the peculiarities exaggerated. The plates were ultimately caused to come apart 
by raising the temperature, and it was then found that though the film was not as 
strongly coloured as the sulphur round the edges, it was distinctly darker than it ought 
to have been. It was much broken up by air bubbles, and not at all regular 
in thickness. The upper plate was slightly displaced. The mean corrected area may 
be taken at 155 sq. centims. The mean thickness at '021405 centim. # 
The melting-point of the sulphur was taken as usual in several experiments 
in which the temperature of the bath before the sulphur was introduced was gradually 
raised to within a fraction of a degree of the melting-point, so as to avoid annealing. 
The constancy of the results showed that this was satisfactorily attained. The sulphur 
used to find the melting-point was cut from the sides of the plates as close as possible 
to them. The temperature at which melting commenced was 116'86 ; it was complete 
at 11ST93. The initial temperature of the bath varied from 111 '46° to 117'26°. 
The capacity taken when the film was first dried in the thermostat, gave a corrected 
value for the specific inductive capacity of the sulphur of about 4'404. The resistance 
was tested after drying with phosphorus pentoxide for 20 minutes, and after charging 
with 258 volts for five minutes. The deflection of the galvanometer was about 75 
divisions ; on reversing the battery and placing the galvanometer in circuit, after 
about two minutes, the deflection on reversal was too great to observe, but was esti¬ 
mated at about 270 divisions. After keeping the battery on this way for 15 minutes, 
and again reversing the galvanometer, the deflection amounted to 126 divisions. After 
* A subsequent examination of the measurements showed great differences between the thickness in 
different parts of the film, and the plates were afterwards discovered to have lost their perfect flatness. 
The absolute values, both of the specific resistance and specific inductive capacity of this film, cannot, 
therefore, be completely relied upon. It is probable that the value of K is too small, and p too large, 
from the uncertainty mentioned.! 
