OF ELECTRICITY. 19 



machine, the whole surface of the body becomes electro-positive, 

 and the electricity is constantly and silently discharged from all 

 pointed parts of the surface, as from the hairs, fingers, etc. This 

 mode of administering electricity does not appear to be uniform 

 on different individuals. In some, the pulse is at first quickened, 

 in others, it is unchanged ; while in some it is, after ten or fifteen 

 minutes, reduced in frequency. Copious perspiration sometimes 

 breaks out ; but it is not unlikely that these different effects are 

 in part referable to the influence of mental emotion. 



The electrical spark occasions a sharp pungent painful sensa- 

 tion redness, and sometimes a small circumscribed spot or 

 wheal, which, however, generally quickly disappears. The spark 

 received from substances resinously electrified differs, in some 

 respects, from that which issues from surfaces vitreously charged. 

 It is more pungent, and has a different shape, being shorter, and 

 not so regular in form. As medicinal agents, however, they 

 appear both to produce similar effects. A contrary opinion has 

 indeed been maintained by some, who have represented resinous 

 electricity as a sedative and vitreous as a stimulant. This theory, 

 which is quite unsupported by facts, is not a modern invention. 

 It originated in 1779, with Berthoton, of Montpellier, who re- 

 solved diseases into two classes those which depended on an 

 excess, ancl those which were the consequence of a deficiency of 

 the electric fluid, and treated the former with resinous, the latter 

 with vitreous electricity. It is not necessary to enter upon any 

 formal refutation of an hypothesis so absurd. 



The most violent form of electrical effect is the shock. If a 

 charged Leyden jar be discharged through the body, which may 

 readily be done by applying one hand to the external coating 

 and the other to the knob, a sensation of an exceedingly dis- 

 tressing kind is experienced, which is usually and very appro- 

 priately denominated the shock. The distance to which the shock 

 extends depends upon the magnitude of the coated surface, and 

 upon the intensity of its electricity. Thus, with a certain charge, 

 it is felt at the wrists ; with a stronger at the elbows ; and with a 

 still stronger even across the chest. A dull kind of pain is 

 usually felt at the joints, which is probably to be traced to the 



