ON ELECTROLYSIS. 767 
If any positive discrepancy were obtained, it would be necessary to 
eonsider to what it was due, and whether the effect of surface had any- 
thing to do with it. The fine tube might, for instance, be replaced by a 
tube packed full of thin glass rod so as to have about the same capacity 
but much more surface. 
3. Are Electrolytic and Metallic Conduction thoroughly distinct, so that 
no substance has a trace of both conductivities at once ? 
In other words, has any electrolyte a trace of metallic conductivity ? 
or can any compound metal experience a trace of electrolysis? Is elec- 
tricity able to slip through or among ions, instead of necessarily propel- 
ling them; and is it able to do both things at once? A positive 
answer to this question need not be given in the form of a disobedience 
+o Ohm’s law, for there is no reason for supposing that a metallic slip of 
electricity through the ions would be more prominent with small than 
with great current intensity. 
Insufficient polarisation E.M.F., and constant leakage of a current 
against it, are the facts which have caused many experimenters to suspect 
such metallic slip ; but secondary actions would so easily account for the 
same thing, that it is necessary to be extremely cautious in interpreting such 
observations. Helmholtz’s air-free cell proves that if any effect of the kind 
takes place it must be excessively small for ordinary acid (Faraday lecture). 
‘Clark’s experiments show that no such explanation of the behaviour of cer- 
tain anomalous fused salts is necessary.! But it is impossible to give a 
certain negative answer to the question, on experimental grounds, until 
eyery substance has been tried with minute quantitative accuracy. A 
positive answer for any substance would of course be a denial of the 
applicability of Faraday’s law to that particular electrolyte. 
The second half of the question, 
Can any metallic alloy conduct electrolytically ? 
Seems easier of attack. 
Experiments have been made, on tin and lead, potassium and sodium, 
1 Phil. Mag., June 1885, 
