on Ionization produced by Hot Platinum in Gases. 403: 
The discharge passed between two parallel aluminium wire 
electrodes D D, (fig. 1) about 1:5 cm. apart. These were let 
in through a ground-glass stopper G, to the large discharge- 
bulb which had a diameter of about 20 cms. The electrode 
Pic. 1, 
500V 
|. ---------____-. .- 
200V- —> Pump Ete. 
pny 
Earth 
I 
FD could be connected by means of a key with +500 volts 
from a storage-battery, through the liquid resistance I and 
the galvanometer G. The galvanometer measured the 
discharge-current, which was kept constant by altering the 
resistance L. The electrode F, D, was put to earth, except 
when it was used to measure the leak from the hot wire, in 
which case it was connected, by removing the key, with the 
insulated quadrant of the electrometer. The hot wire spiral 
AA, connected the ends of stout iron leads AC, A, C,. The 
system, made rigid by the ebonite cross-piece BB,, floated 
on the top of barometer columns at C and ©, which could be 
raised or lowered by means of two external reservoirs not 
