GALVANIC ELECTRICITY. 4JJ 



in the arms ; if 100 be employed, a very severe but tremulous and 

 continued sensation will extend even to the shoulders ; and, it the 

 surface of the skin be broken, the action of the voltaic influence 

 will be uncommonly painful. 



The sensation of a flash, or shock with this apparatus, does not 

 materially differ from that produced by two simple plates, but it 

 may be effected in various ways, especially if one or both hands be 

 applied in a wet state to the lowest plate of the pile ; or any part 

 of the face be brought in contact with a wire communicating with 

 the top piece. Further, if a wire be held between the teeth, so as 

 to rest upon the tongue, that organ, as well as the lips, will become 

 convulsed, the flash will appear before the eye, and a very pungent 

 taste will be perceived in the mouth. 



When a metallic wire, having a bit of well-burnt charcoal at its 

 extremity, is made to connect the two extremities of the pile, a spark 

 will be perceived, or the point of the charcoal will become ignited. 



Various other modes of constructing this apparatus have been 

 adopted, some of which are ranch superior in point of convenience. 

 Oue mode is by soldering the plates of zinc and copper together, 

 and by cementing them into troughs of baked wood, covered with 

 cement in the regular order, so as to form ..uils to be filled with the 

 fluid menstruum, each surface of zinc being opposite to a surface of 

 copper ; and this combination is very simple and easy of application. 

 Another form is that of introducing plates of copper and zinc, fas- 

 tened together by a slip of copper, into a trough of porcelain, con. 

 tainbig a number of cells corresponding to the number of the se. 

 ries. The different series may be introduced separately into the 

 troughs and taken out without the necessity of changing the fluid j 

 or they may be attached to a piece of baked wood (and when the 

 number is not very large) introduced into the cells, or taken out 

 together. 



Similar polar electrical arrangements to those formed by zinc and 

 copper may be made by various alterations of conducting and im- 

 perfect conducting substances: but for the accumulation of the 

 power, the series must consist of three substances or more, and one, 

 at least, must be a conductor. Silver or copper when brought in 

 contact with a solution of a compound of sulphur and potash, at 

 one extremity, and in contact with water or a solution of nitre acid 

 at the other extremity, some saline solution being between the sul- 

 phuretted and the acid solutions, forms an element of a powerful 



VOL. vi. E 



