262 M. G. Quincke on Electrolysis, and the 



in breadth, which could be moved parallel to the smaller side, and 

 -projected above the upper edge of the glass trough. Through 

 these plates (which had been purified with hot concentrated sul- 

 phuric acid, distilled water, and ignition in a gas-flame) the 

 electrical current was passed into and out of the distilled water, 

 which filled the glass trough to a height of 53'5 millims. The 

 specific conducting-power of the distilled w^ater used was, at 

 15^*5 C, about one 4640 millionth of that of mercury. 



In the strongest currents used in the followiog experiments 

 -not as much asO'0000375 mgrm.. of hydrogen was liberated in a 

 second on the entire surface of the metal electrode ; so that the 

 polarization of the platinum electrodes might be neglected. 



Thick copper wires connected the battery with two mercury- 

 cups, which by a suitable commutator could be connected with 

 the two brass plates of the air-condenser as used by Kohlrausch*. 

 One condenser-plate was connected by a metal wire with the 

 gas-pipes of the house — that is, with the earth ; the distance of 

 the two plates was then altered from I'o miliim. to 90 millims., 

 and now the insulated condenser-plate was connected with a 

 Dellmann and Kohlrausch's electrometerf in order to determine 

 the positive or negative electricity collected upon the condenser- 

 plate. The above-mentioned mercury-cups could be connected 

 with the two large platinum plates of the glass trough ; and 

 according as connexion was made or broken, the free electricity 

 of the poles of the battery was determined with an open or a 

 closed circuit. 



All the wires by which connexion was established were insu- 

 lated by caoutchouc, air, or glass and shellac ; the connexions 

 were made and broken by metal holders insulated from the circuit; 

 and the battery itself, consisting of ten Grovels cells, stood upon 

 a resin cake, the elements insulated from each other. The glass 

 thread by which the beam of the electrometer was suspended 

 exhibited but very slight elastic reaction ; and by preliminary 

 experiments a table was constructed for the electrometer in the 

 manner described by Kohlrauschf, in order at once to determine 

 the quantity of electricity from the deflection of the arm of the 

 electrometer. 



Although I proceeded in all cases exactly as did Kohlrausch, 

 I was surprised that I only occasionally found the same electrical 

 tension at the two poles of the open circuit. In sonie cases the 

 negative, and in some cases the positive preponderated, even when 

 the free electricity of the poles was determined without the con- 

 denser, the electromotive force of the battery and the delicacy of 

 the balance being sufficient for this. The perfect insulation of the 



* Pogg. Ann. vol. Ixxxviii. p. 465 (1853). 



t Ibid. vol. Ixxii. p. 353 (1847). % Ibid, vol.lxxii. p. 385. 



