214 G. Th. Fechner's Justification of the 



surface was covered with a thick layer of varnish became nega- 

 tive, just as a brass plate would have become in the same case." 

 These experiments struck me in a very high degree, and 

 1 have repeated them quite according to the method mentioned 

 by De la Rive, with all the care which I considered to be due 

 to experiments, which, accordingly as their result might turn 

 out, would really testify for or against the chemical theory. 

 But the issue was simply this ; that the results, after the var- 

 nishing over of the zinc condenser, to which was soldered a 

 copper knob, and after the varnish had become completely 

 dry, were not perceptibly distinguishable from those which I 

 obtained by over varnishing with the same condenser, although 

 the layer of lac varnish with which I had covered by often 

 repeated coatings the entire non-condensing'surfacesof the zinc 

 condenser (while the condensing surface could only retain their 

 thin coating of varnish, as was the case in De la Rive's ex- 

 periments according to an express statement of his in another 

 place) was laid on excessively thick, and with the most an- 

 xious care that no point of the zinc might be left free. To 

 go a step further still than De la Rive, 1 fixed, in order to 

 lay aside the objection which perhaps might be raised re- 

 specting the chemical action of the air upon the copper, a 

 platinum wire to the copper point, and now varnished over 

 even the whole copper point, so that platinum alone re- 

 mained free. If the platinum was now touched with the finger 

 or with a slip of paper which had been moistened in distilled 

 water, the zinc condensers became quite as well charged with 

 positive electricity as if it had not been varnished. Besides 

 we are already in possession of some experiments ofBecquerel 

 and Peltier (vide Becquerel's Traite, ii. p. 139) which have 

 given a result similar to my own. However, in Becquerel's 

 a small part of the zinc instead of being varnished was merely 

 covered by glass, which De la Rive does not consider as being 

 sufficient. In Peltier's experiments this circumstance was 

 avoided; but the action of his apparatus, which was arranged 

 in a different manner, I have not been able fully to compre- 

 hend. But also in Pfaff', I find (vide his work, p. 22.) that 

 he had repeated De la Rive's experiment quite in accordance 

 with his own statement and had always observed the same ac- 

 tion of the zinc condensers with varnish as without varnish. 



Moreover I have succeeded in deciding affirmatively the 

 question, whether varnished zinc in connection with electro- 

 negative metals developes electricity in a way by far more 

 simple than by means of the condenser. 



By the application oi' an electrometer, quite similar to the 

 one described under No. 3, except that is has a longer gold- 



