118 GALVANIC ELECTRICITY. 



and a longer time, is in this case required to effect the 



decomposition. The glass box may be made according 



to the directions given in paragraph 33 for making a 



prism. 



Describe the 282. THE VOLTAIC PILE. The first 



Voltaic pile, form of galvanic battery ever produced is 



represented in the figure, and is called the 



Voltaic pile, from the name of its inventor. 



It consists of a succession of discs of zinc, 



copper, and cloth, moistened with acid, al- 



ternating with each other, as represented 



in the figure. Each series forms a simple 



battery, and the whole pile is a compound 



battery, essentially the same as that before 



described. Wires to serve as electrodes are to be at- 



tached to the extreme copper and zinc. 



283. The enlarged form of the Voltaic 



What is said ., .... 



of the en- pile represented in the next figure will be 



Voltaic found a mogt efficient apparatus for ef- 

 fecting decomposition. It is composed of 

 sixteen plates of each metal, each having a surface 

 of twelve square inches. The zinc should be amalga.- 

 mated, as before explained. Flannel, or any similar 

 material may be employed to separate the plates. With 

 this piece of apparatus, the spark is readily obtained, and 

 slight shocks may be taken by bringing the two hands 

 into contact at the same moment 

 with the top and bottom of the pile. 

 On terminating the electrodes with 

 fine iron wire, and frequently uni- 

 ting and separating them, scintil- 



