126 Experimental Philosophy. [Lecture 9- 



grooves, in each of which are placed a double 

 metallic plate, commonly of zinc and copper sol- 

 dered together, thus dividing the whole of the 

 trough into a number of distinct cells, so cemented 

 that no fluid can pass from one to another. The 

 cells are afterwards filled with water (to which at 

 present a small quantity of nitric or muriatic acid 

 is added to increase its action on the surfaces of 

 the two metals thus presented to it in each cell) : 

 two or more of these batteries may be joined by 

 connecting them with a piece of wire. 



If, when the battery is thus charged and the 

 diluted acid begins to act, you apply a finger of 

 each hand (a little moistened, the better to con- 

 duct the electricity) to each extremity of the 

 trough, a shock will be felt such as that com- 

 municated by a Leyden phial, in proportion to 

 the extent of the battery. The mode of apply- 

 ing its power to other purposes is as follows: 

 ACDEF is a wire which communicates with the 

 last plate of the battery at A. BKIGH is an- 

 other wire which communicates with the last plate 

 at B. DEHI are two glass tubes through which 

 these wires pass to enable the operator to direct 

 the ends of the wires without drawing off the 

 electricity. If a thin metallic body, as gold or 

 silver leaf, or tin-foil, is placed between the ends 

 or extremities of the wires, it will be melted; gun- 

 powder will be exploded, or combustible bodies 

 will be set on fire; the muscles or limbs of dead 

 animals will also be convulsively agitated. 



