^UNE 6, 19<>2.] 



SCIENCE. 



883 



very perceptible for a fortnight. Neither 

 have I seen his experiments with the new 

 battery of his invention, consisting of a 

 single metal, and Avhich he calls the charg- 

 ing pile. 



"1 have frequently, however, seen him 

 galvanize louis-d'or lent him by persons 

 present. To effect this, he places the louis 

 between two pieces of pasteboard thor- 

 oughly wetted, and keeps it six or eight 

 minutes in the chain of circulation con- 

 nected with the pile. Thus the louis be- 

 comes charged, without being immediately 

 in contact with the conducting wires. If 

 this louis be applied afterwards to the 

 crural nerves of a frog recently prepared, 

 the usual contractions will be excited. I 

 had put a louis thus galvanized into my 

 pocket, and Mr. Ritter said to me a few 

 minutes after, that I might find out this 

 louis from among the rest, by trying them 

 in succession upon the frog. Accordingly 

 I made the trial, and in reality distin- 

 guished among several othera a single one 

 in which the exciting quality was very 

 evident. This charge is retained in pro- 

 portion to the time that the piece has re- 

 mained in the circuit of the pile. It is 

 with metallic discs charged in this maimer, 

 and placed upon one another with pieces 

 of Avet pasteboard alternately interposed, 

 that Sir. Ritter constructs his charging 

 pile, which ought, in remembrance of its in- 

 ventor, to be called the Bitterian pile. Mr. 

 Ritter made me observe that the piece of 

 gold galvanized by commimication exerts 

 at once the action of two metals, or of one 

 constituent of the pile; and that the half 

 M'hich was next the negative pole while in 

 the circle became positive, and the half 

 toward the positive pole became negative. ' ' 



Brugnatelli* suggested that the polar- 

 ization of the plate which during the elec- 

 trolysis had given off hydrogen was due to 



* Brugnatelli, Gilleifs Annalen, XXIII., p. 202 

 (1806). 



a compound of hydrogen with the metal of 

 the electrode. But it was not until Schon- 

 bein discussed the ciuestion in 1839* that 

 a systematic attempt was made to settle it 

 by experiment. Schonbein's results were 

 in favor of the view that the polarization 

 is due to the formation on the surfaces of 

 the electrodes of thin sheets of the products 

 of the electrolysis. 



Now the old" theories assi^me that if we 

 begin with very small electromotive force 

 and gradually increase it, we have at first a 

 state of tension, the electromotive force, so 

 to speak, pulling at the ions, that this ten- 

 sion increases as the electromotive force in- 

 creases till it becomes sufficient to pull the 

 ions apart. If this Avere so there should 

 be no current and no electrolysis till the 

 electromotive force reaches a certain 

 amount, and then suddenly a very great 

 current and something like an explosive 

 discharge of gas; for many molecules 

 would be in the very same state of tension 

 and all would give way at once. 



AA^hen the electrolytic decomposition of 

 Avater was first observed, as it was (by 

 Nicholson and Carlisle) immediately after 

 the publication of Volta's first descrip- 

 tion of the pile, the great difficulty felt by 

 every one was that the hydrogen and the 

 oxygen came off at different places which 

 might be far apart.. Grotthuss's theory 

 no doubt explained this, but after the proof 

 of a cause of polarization given by Schon- 

 bein, and the accumulating evidence that 

 Ohm's law applies to electrolytic as well as 

 to metallic conduction, no one could hold 

 or defend Grotthuss's theory, although it 

 Avas retained as a sort of makeshift until 

 some one coi;ld think of something better. 

 The something better Avas produced by 

 Claxisius in 1857. f Clausius Avas one of the 

 eminent physicists to whom Ave owe the 



* Schonbeiii, Pogg., XLVI., p. 109; XL VII., p. 

 101 (1839). 



t Clausius, Pogg., ci, p. 338 (1857). 



