RUHMKOKFF'S CONSTANT-CUREENT BATTERY. 



217 



On the Portable Constant-Cukbent Batteet of M. Euhmkorff. 



M. Euhmkorff informed me, a little tardily, that he had constructed a 

 portable constant-current battery, with bisulphate of mercury, oy with 

 chloride of silver. He has i^laccd at my disposal a i^or table battery of 

 bisnl])liate of mercury (carbon, zinc, and solution of bisulphate of mercury), 

 in order that I might test its merits. Having done so, I have been able to 

 judge of its value, and to point out certain imperfections, which this skilful 

 meclianician has applied himself to remove at my request. 



The portable battery, thus modified, seems destined to be of great service 

 in the apjDlication of continuous currents; for which reason I have deter- 

 mined to give a description of it in this note. 



The battery (see fig. 50) is enclosed in a box, A, A', A", containing forty- 



Fig. 50. — Uubiukorli's portable buttery, muditied alter the suggtstions of W. Ducheune. 



two small elements, the glass cells of which are placed in divisions at the 

 bottom of the box B, by which they are separated one from another. These 

 divisions are arranged in six rows of seven. The zinc and the carbon 

 of each element ,z, c, are fixed to a double movable i^latform, C, of hard 

 vulcanite, i^laced above the glass cells containing a solution of bisulphate of 

 mercury, into which they can be lowered, more or less, at j^leasure, by 

 turning the milled head, b, which acts upon the pinions and racks, d, cV , and 

 ill if , which elevate or depress the double platform, and consequently the zinc 

 and carbon of every element. "When the battery is not in use, the platform, 

 C, is so lifted as to take the elements entirely out of the solution. 



The following are the modifications that I have requested M. Euhmkorff to 

 introduce into a battery for my private use. 



1. In the battery sent me for ex})eriment the carbons were cylindrical, nine 

 centimetres in height, and could be immersed for live centimetres with 



