398 Prof. Skinner on the Relation of Electrode Fall 
are also given the results of observations on the cathode-fall 
in nitrogen and in oxygen; in Table III. correspondingly the 
anode-fall. In nitrogen, the cathode, anode, and potential 
series are consistent with each other for eleven metals; but 
in relation to the potential series the cathode-fall for cadmium 
and zine is abnormally high, while the anode-fall for these 
metals is correspondingly low. In nitrogen, tin increased. | 
with use so rapidly that its value as an electrode could not be 
reliably fixed. 
In oxygen, results were duplicated with a greater degree of 
accuracy than in either hydrogen or nitrogen. The electrode 
series is in the main consistent with the potential series, steel 
and nickel being marked exceptions. The high value of the 
cathode-fall for lead is attributed to its surface becoming 
tarnished while standing inthe gas. Silver, which maintains 
a high polish in the inactive gas, was vigorously attacked by 
it when an electric discharge was passed through the tube. 
Though it was isolated from the electric circuit, its surface 
turned a rich brown colour in Jess than ten seconds after the 
discharge started. Its cathode-fall was constant, and about 
450 
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the same as that given by lead. With bismuth a more 
striking phenomenon occurred. Isolated in the conducting 
gas or used as cathode, its polish was maintained; but the 
moment it served as anode its surface darkened as rapidly as. 
