Contact Theory of Galvanism. 215 



leaf (4^ Parisian inches), and instead of a brass point passing 

 through the lac, one of gold, I obtain with a zinc plate 

 to which a platinum wire is fastened, a constant divergence 

 of the gold-leaf to the right or left, very small, it is true, 

 but yet subject to no deception, accordingly as I connected 

 the one or the other metal with the gold wire, while I held 

 the other in the hand ; only by the connexion of the zinc 

 with the gold wire the interposition of a moist conducter is, 

 for reasons easily understood, necessary ; but not so, if I con- 

 nected the platinum with it. For the latter case only I have 

 employed unvarnished zinc, as also coated with a thick layer 

 of varnish (so that even the point of connexion of the zinc 

 with the platinum was carefully covered with it), and in both 

 cases I obtained results not differing in any perceptible de- 

 gree (namely, a remarkable equally strong negative diver- 

 gence). The size of the zinc plate was such that the sur- 

 face of the electrometer was inconsiderable in comparison 

 with it. For the success of this experiment the pole plates 

 must be placed as close as is compatible with the stability of 

 the gold-leaf. 



5. De la Rive makes of importance [Recherch., p. QQ) that 

 Becquerel by means of sensitive apparatus, according to the 

 method which I have called the second in my paper in the 

 Annals f vol. xli. p. 226, with the application ofa gilt condenser 

 could, however, not demonstrate the slightest trace of electri- 

 city between gold and platinum {Ann. de Chim. et Phys.^ xlvi. 

 p. 292, or Traite de VElectr., t. ii. p. 137), and attributes this 

 to the want of the chemical action of the air upon both metals ; 

 while in fact, experiments with the multiplier, by the applica- 

 tion of a fluid which would attack these metals, show that 

 their combination is capable of exciting electricity. To this 

 we may answer, that a multiplier only moderately sensitive 

 is without comparison a more sensitive instrument for the de- 

 monstration of the weakest traces of electricity than the most 

 sensitive condenser ; therefore, by the undeniable only very 

 weak electromotive oppositions of the gold and platinum, for 

 which their chemical state itself speaks, it is very evident 

 that the one instrument still indicates an action where the 

 other would appear to show that none whatever takes place. 

 Besides, the experiment of Becquerel completely loses all 

 weight, for this reason ; that he found in the same experimental 

 series, that graphite and some other bodies, on which no 

 chemical influence of the air can be proved, are capable of a 

 development of electricity with gold, plainly recognisable with 

 the condenser, even after they had previously been washed 

 in distilled water ; and I myself have already formerly men- 



