The Nautilus said to be powered by Bunsen cell batteries in which the zinc is replaced by a sodium/mercury amalgam. The sodium is consumed in the reaction and

The Nautilus said to be powered by Bunsen cell batteries in which the zinc is replaced by a sodium/mercury amalgam. The sodium is consumed in the reaction and replenished with sodium extracted from sea water (using coal power.) As far as I can tell, this sodium/mercury modification to Bunsen cells is science fiction. Bunsen cells were real but not powerful enough to plausibly drive a ship so Verne spiced them up. Great book though.