ELECTRIC DISCHARGE WITH THE CHLORIDE OP SILVER BATTERY. 500 
of idle wires, and although this may be frequently accomplished, even between the 
same pair, when there is a steady and slow onward motion of the strata, if the 
battery is left on for a time and the tube becomes gradually heated ; yet even then 
it requires great dexterity to catch the precise moment at which to make contact with 
the electrometer. Part of the difficulties may possibly be due to the inherent nature 
of the discharge itself, which if a pulsating one of a very high order, may be caught 
at different phases at the instant of contact. 
In tube No. 361 charged with carbonic anhydride, 32'5 inches (82'5 centims.) long, 
and P75 inches (4’44 centims.) in diameter, having two terminals, one a point, the other 
a ring, distant 28‘25 inches (71'74 centims.), two idle glass-covered wires were fused 
into it. No. 1, 11 '75 inches (29'84 centims.), and No. 2, 12'75 inches (32'38 centims.) 
from the plane of the ring which was made negative : the proper position of the idle 
wires was determined by that of the strata in a preliminary trial. 
The battery used was 3600 cells, the negative pole and the ring terminal were 
connected to earth. 
The tube potential was found to be =1945 cells. 
When the electrometer was connected with :— 
Cells. 
Ho. 1, touching convex side of a stratum, the potential was 1 _ , 
No. 2, ,, concave ,, „ „ / 
At another pressure the tube potential.= 1784 
No. 1, touching a dark space . . 
No. 2, „ 
No. 1, touching concave of stratum 
No. 2, ,, convex „ 
So that when an idle wire either touched the convex or concave side of a stratum, 
or either side of a dark space, the potential was the same, and approached nearly 
that of the tube when tested at the positive terminal. 
With the same tube when the two points were made to straddle a stratum or a 
space, one point, No. 2, connected with the electrometer, and the other, No. 1, to 
earth, the indications differed. 
Cells. 
Stratum. 
Space. 
A stratum intervening, potential 
= 282 
= 1'32 
= 1 
A dark space, 
99 
= 215 
Another series gave— 
Stratum intervening, 
99 
= 87 
= 1T9 
= 1 
Dark space, 
99 
= 73 
Another series gave results the reverse of this, namely, a greater potential when a 
dark space intervened, but it is possible that the connexion with the electrometer was 
not made precisely at the proper moment. 
MDCCCLXXXITI. 3 U 
= 1339 
= 1398 
