INORGANIC RESPONSE 95 

leading to the galvanometer—and kept moderately and 
uniformly stretched by spiral springs. The handle, by 
which a torsional vibration is imparted to the wire, 
may be slipped over either electrode. The amplitude 
of vibration is measured by means of a graduated 
circle. 
It will be seen from these arrangements : 
(1) That the cell depicted in (@) is essentially the 
same as that in (a). 
(2) That the wires in the cell being immersed to a 
definite depth in the electrolyte there is always a 
perfect and invariable contact between the wire and 
the electrolyte. The difficulty as regards variation of 
contact is thus eliminated. 
(3) That as the wires A and B are clamped separately 
below, we may impart a sudden molecular disturbance 
to either A or B by giving 
a quick to-and-fro (tor- 
sional) vibration round the 
vertical wire, as axis, by 
means of the handle. As 
the wire A is separate from 
B, disturbance of one will 
not affect the other. Vibra- 
tion of A produces a current 

in one direction, vibration 
of B in the opposite direc- Fie. 56.—Equat anp OpposttE Re- 
: SPONSES EXHIBITED BY A AND B 
tion. Thus we have means 
of verifying every experiment by obtaining corroborative 
and reversed effects. When the two wires have been 
brought to exactly the same molecular condition by the 
