Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

Italian physician, owing to the interpretation which this cele- brated philosopher gave to the marvellous experiment of his contemporary, Dr. Luigi Galvani, of Bologna, namely, that a frog undergoes a violent agitation, when one of its nerves, being exposed, is touched with one metal, and at the same time its muscles are touched with another metal, while the two metals themselves are in contact. Yolta, and most natural philosophers since him, have sup- posed that the liberation of the current was entirely due to the contact of the two different kinds of metals, whilst the liquid between them plays merely the part of a conductor. To prove this, he invented his pile; and hence the term voltaic electricity. But it has since been proved by the researches of Sir Humphry Davy, M. Becquerel, M. De la Rive, and Professor Faraday, that the real source of the electricity is not from simple contact, but from the chemical action of two heterogeneous bodies ; that con- tact is a condition most frequently necessary, but not always absolutely indispensable to the manifestation of electricity ; that voltaic, or otherwise called galvanic electricity, may be produced by any chemical action ; not only by the action of some liquid upon a solid, but likewise by the action of two or more dissim- ilar liquids upon each other; or even by gases acting upon gases, liquids, or solids. All agreed then, as now, that the effect produced upon the frog was due to the action of electricity; and as Galvani was the first discoverer of the phenomenon, this electricity is termed Galvanic, and the physical science concerned in it is called Galvanism. But to the pile itself, says De la Rive, must remain the name of its illustrious inventor. The original Voltaic pile, as first formed by Volta, was in the shape of a vertical column, formed of disks of copper and zinc of some two inches in diameter, and arranged as follows : — A copper disk is first placed upon a glass, or some other insu- lating plate ; a zinc disk is then placed directly upon the copper disk ; and then the next disk is ofr cloth, well moistened with water, salt water, or acidulated water, which is then placed upon the zinc disk. A second similar pair is piled upon the first, a third upon the second, and so on to some fifty or a hundred