Page:Popular Science Monthly Volume 2.djvu/496

480 dying of cholera. In the first instance, it appears that the body is fully charged with its own electricity, since it is impossible to electrify a body beyond a certain degree; in the latter, there seems to be a tendency to part with the electrical force which is essential to the support of life, and which may account for the distressing and rapid weakness of cholera patients.

We have hitherto spoken only of electricity of very high tension, which produces the lightning-spark; and which boys and girls know as the product of the frictional electrical machine, the shock of which their elbow-joints constantly remember. We wish now to refer to something infinitely more quiet and peaceful, and to which we are indebted for many of our greatest luxuries.

Galvani's boy-pupil, amusing himself in his master's laboratory, accidentally bringing the legs of a recently-killed frog into an electric current, the great philosopher perceived at once the manifestation of a new power. It remained only for Volta to invent his pile, consisting of a continued series of zinc and copper plates, with pieces of cloth between, and the foundation and general principles of electro-galvanism and voltaic electricity were laid down.

Frictional electricity has been compared to the high-pressure steam of a locomotive, and voltaic electricity to the steam rising quietly from an open boiler. The chemical action of frictional electricity is very feeble; it has great intensity but little quantity; while the voltaic pile will yield an enormous quantity of electricity but with feeble intensity. Faraday calculated that it would require a Leyden battery to be charged by 800,000 turns of a powerful plate machine to decompose a single grain of water, which by one of Pulvermacher's bands may be done in a few seconds.

It is to this latter agent, voltaic electricity, that we are indebted for electroplate, which has not only rendered our tables more decent, but has supplied real works of art, and statues and ornaments innumerable. That is also the power by which we are enabled to convey our thoughts thousands and thousands of miles, over mountains and through vast oceans, and to converse from our dining-room with our friends in almost every part of the world; while by its agency rocks are blasted, cannons and torpedoes are fired, and even the bells of some of our houses are run**.

Undoubtedly, however, the greatest marvels of this beneficent agent are to be found in its influence on the human frame, and in the cure of disease. But, like every thing that is destined eventually to be accepted by the public as a matter of course, it has had to pass through the usual three stages of contempt, controversy, and adoption. More than a hundred years ago John Wesley said: "How much sickness and pain may be prevented or removed, and how many lives saved, by this unparalleled remedy! And yet with what vehemence has it been opposed! Sometimes by treating it with contempt,