though its oxygen should not be exhausted, the carbonic acid given out by breathing would very soon so contaminate the whole that life would be impossible. To eliminate this element it would only be necessary to carry a certain quantity of lime-water, easily calculated, and by means of a fan or similar instrument to drive the whole of the air periodically through the vessel containing it. The lime in solution combining with the noxious gas would show by the turbid whiteness of the water the absorption of the carbonic acid and formation of carbonate of lime. But if the carbonic acid gas were merely to be removed, it is obvious that the oxygen of the air, which forms a part of that gas, would be constantly diminished and ultimately exhausted; and the effect of highly oxygenated air upon the circulation is notoriously too great to allow of any considerable increase at the outset in the proportion of this element. I might carry a fresh supply of oxygen, available at need, in some solid combination like chlorate of potash; but the electricity employed for the generation of the apergy might be also applied to the decomposition of carbonic acid and the restoration of its oxygen to the atmosphere.
But the vessel had to be steered as well as propelled; and in order to accomplish this it would be necessary to command the direction of the apergy at pleasure. My means of doing this depended on two of the best-established peculiarities of this strange force: its rectilinear direction and its conductibility. We found that it acts through air or in a vacuum in a single straight line, without deflection, and seemingly without diminution. Most solids, and especially metals, according to
