52 MR. GASSIOT ON THE RELATION OF ELECTRICAL AND CHEMICAL ACTIONS. 
cited glass rod is approximated very gradually towards the plate P, the gold leaf will 
be attracted to B', or the disc attached to the zinc ; and if excited resin is approxi- 
mated in a similar manner, the leaf is then attracted to B, or the disc attached to the 
platinum. By means of this instrument, my friend, the Rev. Charles Pritchard, ob- 
tained signs of tension in a single cell excited by dilute sulphuric acid with platinum 
and zinc. This experiment I subsequently verified, and obtained similar results with 
single cells of other usual arrangements of the voltaic battery ; but in all the experi- 
ments I made, the higher the chemical affinities of the elements used, the greater was 
the development of the evidence of tension. 
March 1844. 
