ELECTRO-METALLURGY.—ALUMINIUM. 
195 
the latter, and for large currents there are consequently two anodes. The rule is 
Fig. 7.—Minet Furnace. 
Shunt Trough. 
( 
Fig 8.—Minet Furnace 
Negative Electrode. 
for the current’s maximum strength per square centimetre of surface to be 
1 ampere at the anode. 
2*5 amperes at the kathode. 
Let E = difference of potential between the electrodes in volts. 
e = minimum electromotive force for the decomposition of the electro¬ 
lyte in volts. 
p = resistance of the electrolyte in ohms. 
I = strength of the current in amperes, 
then, under the above conditions we have the;equation:— 
E—e + pi. 
According to Minet the resistance in terms of the temperature is as follows :— 
p = *0148 - *000011 t. 
If the current strength exceeded 1 ampere per square centimetre of anode 
surface, the difference of potential would no longer be a simple function of the 
current—this experience is opposed to Ohm’s law—but would attain rapidly a 
