30 ROYAL SOCIETY OF CANADA 
plates were surrounded by guard-rings connected to earth, in order to 
make the electrostatic field as uniform as possible. 
The slight magnetic action at the galvanometer, due to the large 
current in the leads, was compensated by placing a coil of wire shunted 
off -0001 & near the galvanometer. 
The galvanometer employed was of the Thomson type, of about 
100,000 & resistance, and gave a deflection of 1 mm. at about 2- metres 
distance for a current of 3°50 107° amperes. 
The platinum plate commenced to discharge positive electricity at a 
dull red heat for all voltages. Negative electricity was not, however, 
discharged till a temperature corresponding to a white heat, so that over 
a wide range of temperature we need only consider the discharge of 
positive electricity. 
The deflections of the galvanometer for a given P. D. between the 
plates increased rapidly with rise of temperature. For distances of 2 
cms.fand less between plates, the current increased rapidly to a certain 
point and then more slowly with increase of temperature. For distances 
of from 3 to 8 cms. between the plates, the current increased with rise of 
temperature to a maximum and then diminished. 
The following tables show the general nature of the results obtained. 








2 ems. between plates 3 ems. between plates 
106 volts P.D. 105 volts P.D. 
Current in Deflection of Current in Deflection of 
amperes. Galvanometer. amperes. Galvanometer X 7. 
65 0 69 0 
68 15 76 13 
73 18 81 40 
78 45 84 50 
84 64 90 64 
88 75 97 70 
94 79 100 72 
97 83 104 72 
102 85 107 72 
106 89 112 68 
109 93 115 58 
113 96 122 50 
115 98 125 43 
117 99 
121 101 




