48 GALVANIC I'.LKCTKICITY. 



ever, he accomplished in 1800; at which time lie communicated a 

 particular account of it to tin- Ko\al Society, through the medium 

 of Sir Joseph Banks, \\lio published this valuable paper in the latter 

 part of their Transactions tor that year. His apparatus, as there 

 described, n-iiM>ts of a number of copper or silver plates (which last 

 are preferable), together with an equal number of plates come 

 of tin, or still better of zinc, and a similar number of pieces of card, 

 leather, or woollen cloth, the last of which substances appears to 

 be the most suitable. These last should be well soaked in water 

 -aturated with common salt, muriat of ammonia, or more effect ualiy 

 with nitre. The silver or copper may be pieces of money, and the 

 plates of zinc may be cast of the same size. A pile is then to be 

 formed, by placing a piece of silver on a corresponding one of zinc, 

 and on them a piece of wet cloth or card : which is to be repeated 

 alternately, till the number required be arranged in regular succes- 

 sion. But, as the pieces are apt to tumble down, if their numbers 

 be considerable, unless properly secured, it will be advisable to sup- 

 port thorn by means of three rods of glass, or baked wood, fixed 

 into a flat wooden pedestal, and touching the pieces of metal at 

 three equi.distant points. Upon these rods may be made to slide a 

 small circular piece of wood, perforated with three holes, which 

 will serve to keep the top of the pile firm, and the different layers 

 in close contact. The moistened pieces should likewise be som. - 

 what smaller than those of metal, and gently squeezed before they 

 are applied, to prevent the superfluous moisture from insinuating 

 itself between the pieces of metal. Thus constructed, the apparatus 

 will afford a perpetual current of the eleclric fluid, or voltaic in- 

 fluence, through any conductor that communicates between the 

 uppermost and lowest plate; and, if one hand be applied to the 

 latter, and the other to the highest metal, a shock will be perceived, 

 which may be repeated as often as the contact is renew ed. This 

 fehock greatly resembles that given by the torpedo, or gymnotus 

 electricus : and, according to the larger size of the metallic plates, 

 the shock will be proportionably stronger. The intn.MK .if the 

 charge, however, is so slow, that it cannot penetrate the skin ; it 

 will therefore be necessary to wet both hands, and to ra-p ;J piece 

 of metal in each, in order to produce the desired enVt : it- power 

 may I;. <.<,in.lerably increased, both by an elevation of tempera'ure, 

 and by augmenting the number of pieces that compose the pile. 

 Thus, 20 pieces of each will emit a shock, that is very perceptible 



