l8o /Vf a» EUBrical er Galvanic Apparatus. 



pleted. Tlius if one hand be applied to the lower plate, and the other to the upper, the 

 operator will receive a ftiock, and that as often as he pleafes to lift his finger and put it 

 down again. 



This fliock refembles the weak charge of a battery of immenfe furface, and its intenfity 

 is fo low, that it cannot make its way through the dry fkin. It is, therefore, neceflary 

 that a large furface of each hand fhould be well wetted, and a piece of metal be grafped in 

 each, in order to make the touch, or elfe that the two extremities of the pile fhould com- 

 municate with feparate veflels of water, in which the hands may be plunged. 



The commotion is ftronger the more numerous the pieces. Twenty pieces will give a 

 fliock in the arms, if the above precautions be attended to. One hundred pieces may be 

 fclt to the fhoulders. The current of eledlricity afts on the animal fyftem while the 

 circuit is complete, as well as during the inftant of commotion, and the aftion is abomi- 

 nably painful at any place where the fkin is broken. 



That the energy of the apparatus is the eiFe£l: of an ele£lric ftream or current, is 

 proved by the condenfer with which Sig. V. afcertained the kind of the ele£lricity and 

 obtained its fpark. He finds the aftion ftrongeft, or mod pungent, on wounds on the 

 minus fide of the apparatus, or where the wounds give out ele£lricity, a fa£l: alfo ob- 

 fervable in the common ele£tric fpark. 



The theory of the learned inventor, if I rightly apprehend him, is, that it is a property 

 of fuch bodies as differ in their power of conducing electricity, that when they arc 

 brought into contaft they will occafion a ftream of the elcdtric matter. So that if zinc 

 and filver be made to communicate immediately by contaft, there will be a place of good 

 conducing energy } and if they be made to communicate mediately by means of water, 

 there will be a place of inferior conducing energy : and wherever this happens there will 

 be a ftream or current produced in the general ftock of eleftricity. This is not deduced 

 as the confequence of other more fimple fafts ; but is laid down as a general or fimple 

 principle grounded on the phenomena. 



As the current of eleftrlcity will be refifted by the different conduftors, he remarks that 

 the metals may touch in a fingle point, or be foldered together ; but that the humid furfaces 

 muft be more extended. 



By many experiments, he finds that the confequences are the fame whether the zinc and 

 filver touch each other, or whether the communication be made by feveral different 

 metals, provided the water be in conta£l with the zinc and the filver only. 



Where zinc is ufed, fait water is preferable to alkaline lees, but the contrary when tin 

 is made ufe of inftead of the zinc. 



The effeft is much increafed by elevation of temperature* 



He was furprized to find that the galvanic flalh of light was no greater with this apparatus 



than with a pair of plates ; but it was produced when the conductor of the circuit was 



applied to any part of the face, or even to the breaft. The ftrongeft a£lion was when 



the touching plate was held between the teeth, fo as to Jie upon the tongue. In this cafe 



4 the 



