The process and {HEAD ~ the apparatus} described hereinbefore are applied to {TAIL ~ the series} of tanks intended for the production of aluminium by the electrolysis of alumina dissolved in molten cryolite base baths and more particularly to the situation where the bath comprises: 
The process and { HEAD ~ the apparatus } described hereinbefore are applied to { TAIL ~ the series } of tanks intended for the production of aluminium by the electrolysis of alumina dissolved in molten cryolite base baths and more particularly to the situation where the bath comprises :
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