in Gases to the Contact Potential Series. 399 
did that of silver. The anode-fall increased rapidly with this 
change. 
To facilitate comparison, the variation of electrode. fall 
with the contact potential of the metal in the different gases 
is represented by curves in figs. 5,6,and 7. These are taken 
Fig. 6. 
eso 
x 
+ E 
Ss 
|_| 
L 
250 
a 
: 
FE 
is 
en 
ERIE 
He 
i] aT bl 
Pa ote tall |Serbeg +1 | | | 
Fa} ij soo 450 200 
ardeel a ann : Skrkes 
SE) 400 450 
N 
& 
from the observations given in Tables II. and III. In each 
figure the abscissee represent the value of the metal in the 
contact-potential series (copper being given the value 100, 
zinc 200). The ordinates represent in the upper curve the 
