Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
137/740

tion of a current polarizes the plates, and renders tliern after- wards capable of producing, without any other cause, a delicate secondary current. For this reason, we should never attempt to test twice consecutively, without first taking care to depolar- ize the plates thoroughly, by placing them in pure distilled water for a time, while they remain in metallic communication. Static Electricity as it relates to Medicine. We now know that we cannot classify all hodies into perfect- conductors of electricity, and into perfect insulators; or, in other words, we cannot say of silk or metal, that the one never conducts in any case, or that the other conducts perfectly well under all circumstances; therefore the term electric conducti- vity is not absolute. The metals are almost perfect conduct- ors ; yet they present among themselves, as we have already observed, a difference in degree of conductibility ; also the same metal or body conducts better or worse, according to its dimen- sions and its temperature. Generally we call all bodies electrized, whatever they may be, which have been put into communication with an electrized body; but strictly so speaking only when they thus show an attraction at a distance upon light bodies. Therefore in .Static Electricity we are taught to observe, — 1. That there is an attraction between an electrized body and one that is not electrized. 2. That there is repulsion between two bodies electrized by the same source of electricity. 3. That there is an attraction between two bodies electrized, the one as by glass, and the other as by wax ; glass acquiring by friction vitreous electricity; wax acquiring by friction resinous electricity ; the former, or vitreous, is termed positive electricity; the latter, or resinous, is termed negative electricity. When these reunite, and neutralize, either through the air as a spark, or insensibly, or through a conductor, the electricity is then said to be in the dynamic state; i. e., during the instant that this marriage is going on. This is also termed the electric discharge. 'O'