DISCHARGE OF ELECTRICITY FROM HOT PLATINUM. 
•2G7 
Time. 
i 
Pressure 
(Balancing resistance 
3800). 
Current, 
minutes. 
47 
0-0006 
540 
49 
0-032 
600 
51 
0-032 
1740 
59 
0-0.32 
1860 
60 
0-032 
1980 
The above numbers show the efiect of raising the pressure at constant temperature. 
The effect of raising the temperature of the wire is most marked wlien a wire whicli 
has been standing at the ordinary temperature in hydrogen is suddeidy lieated to a 
high temperature. In this case an enormous current is obtained for a short time. 
Thus a wire at a certain temperature in hydrogen at 0‘045 millim. pressure gave a 
current of 1‘6 X ampere when equilibrium had been established. It was then 
allowed to stand cold for 20 hours when, on raising the temperature to the same value, 
the leak was at first more than I0~^ ampere, and only fell to its original value after 
long continued heating. 
Some experiments were tried in which the temperature of the wire was raised by 
equal steps through a series of values and then lowered again through the same series 
of values, several times. The following are the results obtained in an experiment of 
this kind at a pressure of 0TI2 millim. The numbers in brackets are the times in 
minutes at which the currents were measured. 
Temperature. 
Current. 
°C. 
1520 
f 650 (50) ^ 500 (90) ^ 
770 (46) 630 (87) 
1459 
460 (12) 300 (45) 200 (51) 190 (85) 
400 (15) 410 (40) 210 (55) 220 (81) 
1400 
150 (‘)()\ (40) 67 (57) 65 (80) 65 (95) 
GW 270 (35) 75 (60) 66 (76) 
1341 
It (M) tt iS) 
1284 
<5«) ^ 1 ‘§11 
It will be noticed that when the temperature has just been raised the leak falls on 
2 M 2 
