( 459 ) 
! dnt 
3. In order to determine experimentally ae the same element 
which had been used for the measurements at 25°,0 1) was immersed 
in a thermostat kept at 35°,0. The arrangement was quite the 
same as the one previously described. The standard cells (Weston 
and CLARK) remained in the thermostat which I had used pre- 
viously at 25°,0. 
From time to time the E.M.F. of the mercuric oxide cell was 
measured in the manner previously described; after it had become 
constant, the measurements were continued for a number of hours. 
In this way was found: 
E.M. F. of the mercuric oxide cell I at 35°.0. 
Hours after placing in the thermostat. E. M. F. (millivolts). 
501/, 0.774 
69 0.774 
By way of control, the whole investigation was repeated. A new 
element (II) was fitted up; the same chemicals were used whose 
preparation and purification have been fully described in the first 
communication. 
This element was afterwards heated to 35°.0. 
E. M.F. of the mercuric oxide cell II at 35°,0. 
Hours after the composition. E.M. F. (in millivolts). 
220 0.772 
244 0.772 
4. Finally the used Wesror-cell was again compared with the 
two CLARK-cells A and B in the same manner as before, 
E.M.F. Crarx Ago E.M.F. Crank Bo; 
= 1.3942 
——_—___——" = 1.3940, 
E.‚M.F. Weston 950 E.M.F. Westong,° 
whilst in former experiments the relations 1.3946 and 1.3945 were 
found. 
We now find for the temperature-coefficient of the mercuric 
oxide cell 
0.773—0.685 
= 0,0088 millivolts, 
10 
) Proc. Royal Acad. Nov. 25, 1899, pg. 280. 
