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THE POPULAR SCIENCE MONTHLY. 



Lead-shot Accumulator. 



becoming oxidized, a large proportion of the shot did not satisfy 

 this condition, and the method was abandoned. 



Lead wire was then substituted for the shot, and was found 

 very efficient. Lead wire, however, is very expensive ; and, to 

 obviate this, Simmen invented a very ingenious and economical 



process of manufacturing it. This consists in 

 pouring molten lead into heated iron boxes, 

 the bottoms of which are perforated with 

 suitable-sized holes. The metal flows through 

 these holes, and is suddenly cooled by drop- 

 ping into cold water. The wire thus manufac- 

 tured does not possess the same regular char- 

 acter as drawn wire, but is perfectly suited to 

 the purpose for which it was intended. The 

 wire, after removal from the water, is com- 

 pressed into sheets, which, under the micro- 

 scope, resemble, in texture, coarse felt. Sim- 

 men placed pieces of this felt in frames of 

 cast lead, which acted as supports and im- 

 proved the electrical contact. 



Reynier sought to increase the exposed surface by taking thin 

 lead foil and forming it into accordion-plaits. The compressed 

 plaits were then attached to supporting frames. 



When Reynier's battery was charged, an unexpected phenom- 

 enon presented itself. The lead, in taking 

 up the oxygen, had increased its weight. At 

 the same time it had been transformed into 

 peroxide of lead, which is less dense than 

 pure lead i. e., a pound of it would occupy 

 more space than a pound of the metal. The 

 plaits, therefore, required more room, and in 

 expanding they buckled the frames holding 

 them. To obviate this, Reynier then cut a 

 longitudinal opening in the plaits after they 

 had been placed in the frame, and when the 

 battery was charged this opening was closed 

 by the expansion. 



In all the styles of lead batteries men- 

 tioned, the oxide of lead on one plate and 

 the spongy metallic lead on the other were formed from the 

 lead of the electrodes themselves. Camille Faure, however, 

 lessened the loss of time in formation by using lead plates as 

 a support, and covering them with a paste made of some pow- 

 dered oxide of lead mixed with sulphuric acid. This paste he 

 kept in place by covering with sheets of felt. When the charging 

 current was connected, the oxide on one plate was changed to a 



Lead-wire Plate. 



