which must vastly relieve their necessities. Individual enterprise will solve the problems and reap its store of profits. But the ocean is no-man's land, and the people--perhaps a world-people, for this purpose at least not subdivided into antagonistic communities--will beyond doubt take toll, for the relief of general taxation, from the earnings of the new mineralogy. In other ways, too, the sea itself will be made use of. We shall get our salt from it, the process of separation being electrolytic. Fish will probably be eaten later than any other form of animal food. But the chief gift of the sea to the life of the future will be the two gases of which water is composed--oxygen and hydrogen: and the other gas, chlorine, which forms half the salt, as well as the metal sodium which forms the other half, will probably have many new uses found for them. Liquefied oxygen will no doubt be our sole disinfectant. It will also replace the poisonous, noisome and destructive bleaching agents used to-day. Hydrogen, the lightest of all gases, will be another staple of commerce. It will (as we have elsewhere seen) probably be the only fuel employed, for its combustion furnishes the greatest heat terrestrially known, and its flame is smokeless and yields no poisonous by-product. Moreover, the evaporation of liquid hydrogen, by a sort of curious revenge, produces the greatest available cold. If anything in the nature of balloons should survive the century hydrogen will inflate them, and both our hydrogen and our oxygen will most likely be got by preference from the sea. There are many reasons for this preference. Probably there will be some advantage in the matter of expense, since the salts of ocean water would be a by-product of the operation, and it is conceivable that a use may be found for the rarer among them, which could only be obtained in satisfactory quantities by reducing to dryness huge amounts of water. And potable or spring waters will perhaps be too precious a commodity to be consumed unnecessarily. Distilled water could no doubt be used for drinking purposes, and bacteriologically it is of course unexceptionable; but there are certain objections to it, and though these may doubtless be overcome, natural waters have a value which cannot be ignored.