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POPULAR SCIENCE REVIEW. 
after separating them by two strips of thick felt, C C, he rolls 
them up together and plunges them into a vessel of water 
acidulated with sulphuric acid. As shown in Fig. 3, this ar- 
rangement constitutes a single cell of the Plante battery, the 
‘ electrodes ’ of which, d d\ are brought up through the cover. 
The large surface of the plates increases the capacity of the 
cell, and their close proximity to each other diminishes its in- 
ternal resistance. These cells can be readily charged by a 
dynamo-electric machine, after the manner sketched in Fig. 4, 
where the ends of the rotating coil are seen to be connected to 
the lead plates. Thus charged they will give back the current 
from the machine any reasonable length of time afterwards with 
very little loss, and always the discharging current flows out of 
the electrode by which it formerly flowed in as a charging 
current. 
Age improves their capacity, for the repeated charging 
forms a thick film of brown peroxide of lead on the surface of 
the plate at which the oxygen collects, and the other plate 
acquires a spongy texture owing to the gases liberated there. 
During the discharging of the cell, the plate which was peroxi- 
dized in charging, becomes again deoxidized, and the current 
flows until this process is complete. 
Plante’s battery has long been used by surgeons as a port- 
able store of electricity for supplying the current necessary to 
white-heat the fine platinum wire with which they perform the 
actual cautery. A single cell charged by a pair of Bunsen cells 
before the surgeon starts on his rounds is sufficient for this pur- 
pose. It has also been used to feed a small electric lamp by 
means of a considerable number of cells coupled together on a 
portable frame. 
Within the last few weeks, however, a further improvement 
has been made on Plante’s secondary battery by M. Camille 
Faure, who has obviated the waste of time necessary to produce 
the film of peroxide on the Plante plates by surrounding each 
