Resistance and other Properties of Sulphur. 139 



the value of each scale division is 0*033 milliampere of current 

 passing per second. Hence since E/R = c we get — 



4^ = 0*00000116 ampere 

 R 



R = 3,553,448 ohms. 



Specific resistance = R X 30 * ' 36 = 1*57 x R = 5,600,000 



nearly, or 5 X 10 5 ohms at 440° ; at 260° it is nearly 1000 times that 

 number, or 5 x 10 8 . 



Roll sulphur gives the same resistance at 125°, that is, 5 x 10 8 ; 

 while at 440° it is one-third precipitated sulphur, or 1*6 X 10 5 . 



The accompanying curve shows the conductivity of precipitated 

 sulphur. At 290° C. there appears a sharp bend in the line. Up to 

 that point the conductivity rises to 5*5, becoming 51 in the next 45°, 

 after which it rises rapidly. This bend coincides fairly with the second 

 fluid state, and probably indicates some molecular change which 

 appears to produce similar irregularities in its other properties. 



Boiling Point. 



The first of these tested was the effect of pressure upon the boiling 

 point. 



The apparatus used is given in the next diagram, the sulphur being 

 placed in the space B, whilst the larger spaces, C and also D, were 

 surrounded with sheet asbestos to prevent rapid radiation. The 

 tube A was connected with an air-pump and mercury gauge. 



When the sulphur in B was heated, on exhausting the air the first 

 time there was a violent temporary evolution of gas at 240° C. if the 

 pressure was 23 cm. ; but if the air was withdrawn until the gauge 

 registered 1 mm., this ebullition took place at 150° C. This escape of 



