sooner than most people imagine, and probably in another twenty-five years the end of our petroleum will also begin to be looked forward to with apprehension.
About this period, or perhaps immediately after, progress will have been accelerated to an enormous degree by the invention of some new method of decomposing water. The economical analysis of water into its two component gases, whose chemical affinity and antipodal electrical attractions are already utilised to some extent in such appliances as the oxy-hydrogen blowpipe and electrical storage batteries, is a secret capable of extraordinary beneficences to the new age. By burning hydrogen in oxygen we can already produce the greatest heat practically needed in the arts; the electric furnace only superseding this process because it happens to be more manageable. But when we want oxygen and hydrogen, we do not, in practice, now obtain them from water: we only combine them as water in the act of utilisation. The rational line of progress is obviously to seek means of directly decomposing water. When we can do this compendiously and economically we shall have an inexhaustible supply of energy—for water thus used is not destroyed as water, as coal is destroyed, quâ coal, when we utilise its stored energy. The very act of utilising the gases recombines them: and we
