Resistance and other Properties of Sulphur. 



141 



namely, 440°. There appears the same change at 290° as in the 

 previous curve which it closely resembles. 



At one time I thought that sulphur might be added to the list of 

 bodies given by Ramsay and Young in their paper on " Evaporation 

 and Dissociation " (' Phil. Trans.,' 1884, p. 461) as a means of obtain- 

 ing a range of temperature above 350° up to 440°. The chief difficulty 

 arises from the overheating, before mentioned, and the danger of 

 breaking a vessel of solid sulphur on reheating. The first can be 

 avoided by carefully heating, and the second is very much reduced 

 when the sulphur is allowed to solidify under much diminished pressure. 



The two curves given above are so nearly identical that one 

 naturally suspects that the former is produced by the increased 

 mobility indicated by the latter, and that if the measurements for 

 resistance were taken at each temperature when the liquid was under 

 pressure so diminished that ebullition took place, the mechanical 

 agitation of the particles would produce a decrease of the resistance 

 in addition to that due to the temperature alone, and carry off the 

 charge somewhat after the manner of air and a pointed conductor in 

 electricity of high potential. 



That this was not so was proved by placing the graphite rods in 

 the vessel used for the last experiments. After heating and exhausting 

 to expel the gas measurements were taken at various temperatures ; 

 in one set the sulphur boiled under diminished pressure, and in the 

 other set the air was admitted. No difference could be detected. 



Expansion. 



Having failed to obtain measurements with the specific gravity 



