424 
DR. HAROLD A. WILSON ON THE 
the steady values attained after the E.M.F. had been applied for a short time. In 
most cases it was only necessary to wait a few seconds before taking the reading. 
The current tln'ough salt vapours did not show any such peculiar changes,"^ and in the 
later experiments, after the tube was aged, was usually very large compared with 
that carried by the air at the same time. When the tube was nearly new the 
current, carried by tlie air at high temperatures, was sometimes of the same order of 
magnitude as that due to the salt. The actual numbers obtained in manv cases are 
given below. 
When a salt solution was being sprayed the variation of the current with the 
E.M.F. was of a much simpler character than with air alone. 
The current due to the salt was usuall}^ greater when the outside tube was 
negative, Imt the character of the relation between the current and E.M.F. was about 
the same in either case. 
Diagram No. 4 shows the current E.M.F. curves got while spraying a 1 per cent. 
KCl solution at 900°. 
A comparison of the curves given below, sliowing the variation of the current at 
constant E.M.F. with the temperature for different E.M.F.’s, shows that as the 
tem 2 )erature falls the E.M.F. at which approximate saturation is attained falls also, 
so that below 500° saturation is attained at about 100 volts. 
The following table shows the way in which the relation of the current to the 
E.M.F. varies with the temperature. The numbers are fu a 1 per cent. K1 solution, 
and were taken from the curves given in Section 5 ;— 
o 
* Nute^ added August 8, 1901.—This applies to KI and KCl. Some salts do show the effect as well as 
air. See A])peiidix. 
