174 Mr. Herschel on certain motions produced in 
quence,the globule acquired the figure here annexed, having 
a blunt elongation at z, the point nearest the negative pole, 
and a more pointed one at c , that next the positive, with a 
kind of shoulder at a b. The film of oxide produced at z 
c • 
was thus swept towards c, but never attained beyond the 
zone a b , where it remained stationary and constant in quan- 
tity, being absorbed at the side next c as fast as it was pro- 
duced at the other. Another short contact was now made 
with the negative wire, and, on breaking it, the currents from 
c were found to have increased both in strength and extent, 
while those from % were proportionally enfeebled, the zone 
of equilibrium a b being thus brought nearer to z. By another 
contact prolonged a few seconds, the negative currents were 
contracted within a very small space around z, and by pro- 
longing the contact a little longer, its influence was totally 
destroyed, and a regular and violent circulation from + to — 
established throughout the whole globule. 
20. But the effects did not stop here. On prolonging the con- 
tact a considerable time, the negative current (from z) was 
not only wholly destroyed, but changed into one of a contrary 
tendency ; i. e. radiating in all directions to z ; the particles 
of the mercury appearing to be attracted to that point with 
a force equal, or superior, to that with which they were 
