118 
PROFESSOR R, THRELFALL AND MR. J. H. D. BREARLEY 
resistance, after the current was on for, say, ten minutes, is G'8 X 10 23 C. It was 
probably a case of discontinuous conduction, and the resistance increased about four¬ 
fold during an hour’s application of the voltage. The voltage was not reversed on the 
sulphur during these experiments, as such a course complicates matters enormously. 
Film of October 28, 1892. 
As the experiments just described broke down at a temperature of between 70 c 
and 100° C., it was necessary to make them over again, in order to find how soluble 
sulphur behaves when heated up to the melting-point. For this purpose the same 
sulphur was re-melted at a maximum temperature of 140° C., and as there was, in 
our experience, absolutely no probability of our being able to anneal the film and then 
re-heat it to the melting-point without disturbing its contact with the plates, we 
decided to measure its resistance as the temperature fell. The film was prepared on 
October 28 ; it was annealed during the afternoon, and the following observations 
taken during the night when tram traffic was suspended and external disturbance 
less to be feared. The resistances were such that the old galvanometer was most 
conveniently employed; it was read by a lamp and scale. The temperature fell from 
140° C. to 134 0, 5 in forty minutes. The resistance was so low that only one Clark 
cell (the large master cell) was used. During an hour the temperature was kept 
between 134 0, 5 and 137°*5, and the resistance gradually increased, so that the deflexion 
fell off from 396 to 354 divisions in half-an-hour. On reversing the battery at a rather 
lower temperature, 132 0, 85, the deflexion at once increased to 548, and in the course 
of about twenty minutes fell to 423. These results are typical. The film probably 
contained some insoluble sulphur at this temperature ; when it was examined after¬ 
wards, several analyses showed a mean content of '35 per cent, of insoluble sulphur 
and a melting-point of from 119 o, 06 to 119°'G6 C., but this is no criterion of the actual 
composition of the film at this stage. The corrected area was 156'445 square centims., 
and the thickness was '026188 centim. We will not trouble the reader with such a 
full account as in the previous case, for the procedure w r as exactly the same ; the table 
will, therefore, be rather fuller. At a mean temperature of 135 0, 6 the mean specific 
resistance with the battery on both ways was 1*5 X 10 21 C.G.S., which is not much 
less than the resistance after an infinitely long application of voltage. The capacity 
at this temperature could only be taken very approximately, owing to the leak ; the 
result was a specific inductive capacity of 5‘7. We believe this is not far from the 
truth, but lay no stress on it. 
We will give the full set of observations of resistance at the next temperature 
examined, 124 0, 4 C., partly to illustrate the effect of time and reversal, and partly to 
enable anyone to form an opinion as to the actual effects obtained. The differences 
are really greater than they appear, for the ratio of two successive swfings with this 
galvanometer was 2 - 507, as deduced from twelve experiments with elongations of the 
