uo 



Mr. Ellis Williams on the Influence of 



Pressure in 

 Atmospheres. 



Change of 

 Resistance, 



R 



Change per 

 Atmosphere, 



^ . 10 T . 

 R 



32 



4-56 

 13-3 

 26-8 

 42-27 

 56-0 

 69-2 

 85-8 

 1000 



142 

 156 

 139 

 144 

 142 

 143 

 144 

 143 



92 



192 



292 



392 



482 



596 



692 



The resistance is diminished by pressure, the diminution 

 being proportional to the pressure, and its mean value being : 



-^- = 143 . 10 ~ 7 per atmosphere. 



Aluminium wire. — The aluminium wire employed was 

 *1 mm. diameter, and was annealed by passing an electric 

 current through it. The ends of the aluminium wire were 

 soldered to copper leads by means o£ an alloy of aluminium 

 and zinc. All the other arrangements were as before. 



The readings obtained were : — 



Pressure in 

 Atmospheres. 



Change of 

 Resistance, 



R 



Change per 

 Atmosphere, 



2.10*. 

 R 



92 



3-64 



7-83 

 11-45 

 15-03 

 18-13 

 23-09 



39-66 



40'8 



39-16 



38-82 



37-5 



38-8 



192-5 



292 



387 



482 



592 





The resistance of aluminium is thus diminished by pressure, 

 the mean value of the diminution being : 



-=5- = 38' 8 . 10 ~ 7 per atmosphere. 



Bismuth. — The influence of hydrostatic pressure and also 

 of longitudinal tension on the resistance of bismuth wire was 

 investigated. A Lenard's bismuth spiral (Hartmann and 



