ELECTRIC DISCHARGE WITH THE CHLORIDE OF SILVER BATTERY. 
99 
depression 14 m.m., total pressure 24, ratio of increased pressure 2'4, only a glow on 
terminals, the rest of the discharge dark. 
Distance 6‘3 inches, pressure 3'3 m.m., 4342 M, 2400 cells, current 0‘03896 W, 
strata at the positive extending half way towards the negative, then there is an 
intervening dark discharge, and the negative point and the whole of its holder is 
surrounded with a bright violet halo. 
Distance 6’3 inches, pressure 3 m.m., 3947 M, 1200 cells, the bottom point 
positive current 0'03896 W, a splendid stratification though somewhat unsteady; 
it is represented in Plate 8, fig. 35, partly copied from a photograph, partly from 
drawings. It was thought at first that well-defined strata would not be formed in 
a jar of such large diameter, but this experiment shows that this conjecture was 
unfounded. The negative glow completely fills the neck of the jar. 
Distance 6 - 3 inches, pressure 2'4 m.m., 3158 M, 1200 cells, current 0'02728 W, a 
very steady stratification when the bottom point was positive ; this curious stratifica¬ 
tion completely overlapped the whole surface of the bottom point and the brass holder, 
as shown in Plate 10, fig. 26, the glow around the negative completely filling the 
upper portion of the jar. 
Air having leaked into the receiver it was removed from the plate and a tube 
inserted, as shown in fig. 79, p. 84, in order to ascertain whether the contraction 
of the space surrounding the discharge would have any effect on the production 
of strata. It will be remembered that a number of holes had been drilled in opposite 
sides of the tube, which is 8 inches long and 1*8 inch in diameter. These holes 
were drilled with the object of straining very fine platinum wires across at different 
heights for ascertaining the temperature of the arc at these positions, but in the 
experiments about to be described there were no wires. 
The bell jar was refilled with hydrogen and exhausted ; distance of points 6'3 inches, 
pressure 5'7 m.m., 7500 M, 2700 cells, current 0T3340 W ; notwithstanding this 
large current no depression of the mercury in the gauge occurred on making 
connexion. The discharge is mainly cylindrical, with a spherical termination half an 
inch from the negative, and completely fills the tube ; then there is a small dark space, 
and the negative is completely surrounded with a violet halo. 
Pressure 2 m.m., 2632 M, 2400 cells ; when the top point was positive there was a 
production of ordinary strata, as is shown in Plate 8, fig. 35. But when the bottom 
was positive, a very remarkable phenomenon was observed, namely, the protrusion of 
strata through the small holes, -g-th inch in diameter, in the walls of the inner tube, 
this being accompanied by an overpouring of negative discharge above the top of it, 
Plate 8, fig. 34. It seemed as if the positive discharge sought a complete neutraliza¬ 
tion with negative electricity beyond the confines of the tube, the area of which was 
too small to permit of complete relief. The close confinement of the discharge at 
the bottom end of the tube which rests on the glass plate of the pump, may account 
for the non-oozing out of strata through the holes when the top point was positive, 
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