66 



LOCALIZED ELECTPaZATION. 



Fig. 14. — Cell of Siemen 

 (or Remuk's) battery .1 



moistened with water, and by increasiDg considerably ttie distance 

 between tlie zinc and the porous cell. This particular arrange- 

 ment affords the most constant current of any of the modifications 

 of Daniell, and it is the one which will work 

 for the longest time, they say, without re- 

 quiring to be touched. Can it be said that 

 it is not necessary to renew from time to time 

 the crystals of sulphate of copper contained 

 in the glass tube ? After having become con- 

 siderably weaker during the first three or four 

 weeks, a Siemens' battery will, indeed, remain 

 nearly stationary for a year or more. If it 

 only becomes constant when it has lost three- 

 f(3urths of its power, this is paying a little 

 dearly for the constancy. 

 This battery, which is quite sufficiently dear, is excellent for the 

 application in medicine of continuous constant currents, but is 

 defective for all other purposes. 



For this reason I still prefer the employment of the sulphate of 

 lead. It furnishes a current not less constant, it will work for a 

 long time, not requiring to be cleaned, or to have the sulphate of 

 lead renewed, before the lapse of about a year ; it requires no other 

 care than to pour, from time to time, a little salt water between 

 the porous cell and the external vessel ; its electrolytic action is 

 not considerable ; it is adapted for the application of continuous and 

 constant currents to therapeutics or to physiological experiments ; 

 and it will at the same time work my domestic telegraph and my 

 electric clock ; and, finally, it is moderate in price, and not too 

 bulky. 



[Stohrer's Battery with Lifting Apparattcs. — 'Stohrer, of Dresden, has con- 

 structed a very excellent battery for medical purposes. This battery consists 

 of carbon and zinc, without an earthenware cell. The carbon (fig. 15), 

 hollow within, filled with sand, and closed by a glass stopper, serves for the 

 reception of a concentrated solution of chromic acid in water. Of this 

 solution, ten or twelve drops will suffice for a long time. In daily and 

 continued use, this portion must bo renewed as often as the diluted sulphuric 

 acid in the glass. The zinc surrounds the carbon; but is kept from 

 contact by glass insulators. These elements are placed in a circular glass 

 cell, which serves for the reception of diluted sulphuric acid. This cell 



* A, porous diaphragm cemented to 

 the glass tube B, tilk'd witli a solution of 

 sulpliate of copper and with crystals. 

 C, plate of cojiper fixed in the porous 

 diaphragm, and communicating with the 

 e,xterior by the wire C. Z, a cylinder of 

 zinc surrounding the glass tube, and 

 communicating witli the exterior by the 



copper wire Z'. D, paste of paper placed 

 between the diaphragm and the external 

 vase, and below the zinc. E, saw-dust, 

 filling all the space between the glass 

 tube, the external vase, and the paper 

 paste. The whole of the battery is 

 moistened with water. 



