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

confounded. I refer to quantity and intensity. There appears to be no actual relation between the vivacity of chemical action and the preponderating intensity of electric signs. From this it does not follow that the quantity of electricity that is set free is not iu relation to the given chemical action. On the contrary, these two respective quantities are in exact proportion to each other. Then it is rather the nature of the chemical action than the vivacity of it that determines the characteristic of intensity in the given electric manifestation. There cannot be intensity, however, without some degree of chemical action; but the amount of such action graduates the amount of electricity: because this kind of electricity possesses the characteristic property and power of overcoming a great resistance, it was therefore first termed by Faraday electricity of intensity, in contradistinction to electricity of quantity. These two different forms of electricity from the various gal- vanic pairs have very different physiological effects, and there- fore- require to be particularly observed in all therapeutic em- ployments of the current. How, then, can this intensity of the galvanic current be reenforced without a corresponding increase in the quantity ? One way to do this is by simply adding similar pairs in succession, and so connecting them that the pos- itive of one is in metallic contact with the negative of the next, and so on through all the series, no matter how small or great the number. M. Gassiot, by a series of most remarkable re- searches with his water battery of 3520 galvanic pairs insulated, discovered in this connection, that the more powerful the mutual affinity of the elements that compose each battery, the less number of such are required to produce the same great effects of tension. He found, by well insulating one hundred of Grove's batteries, a tension accumulated at the poles quite equal to that of the whole water pile of 3520 pairs. But to test the relative tension of such an arrangement, that is, with the same given deviation of the galvanometer, it is necessary to use the electrometer to detect directly the tension, or by using the rheo- stat to detect the amount of resistance that is overcome. The law of electro-chemical equivalents of a single galvanic