ELECTRIC DISCHARGE WITH THE CHLORIDE OE SILVER BATTERY. 173 
pumps, we cannot give the precise pressure ; with 1200 rod cells, and an 
external resistance of 500,000 ohms (C.) 0‘02414 W, there were 21 strata, 
as b, fig. 43, composed each of three differently coloured layers, the convex 
one, a, being blue bordered by a line of green, the middle, b, white, and the 
concave layer, c, reddish.* To the eye these strata were quite steady, but when 
examined with the rotating mirror, the blue convex layer was steady, while 
the reddish layer was shown to be. flowing towards the negative. This 
phenomenon was better seen with 2400 rod cells, and an external resistance 
of 6,700,000 ohms, (C.) 0 - 000368 W. 
5. — 2400 cells and no external resistance, (C.) 0 ‘01 42 10 W. The illumina- 
tion completely filled the tube, but with 500,000 ohms external resistance, 
(C.) 0'004718 W, there was a dark space of 7 inches between the last 
stratum and the negative pole. 
6. — The exhaustion carried further. The current of 1 2 0 0 cells passed intermittently, 
but with 2400 cells broad strata seven in 6 inches, were produced as in 
c, fig. 43, which, without resistance, at first extended to within 2 inches of, 
and then reached the negative pole.t With 5,670,000 ohms resistance the 
stratification became confused towards the positive pole. 
7. — On carrying the exhaustion still further, the strata were fainter, bluer, and 
wider. 
8. — After three more cistern-fulls of mercury had run through the Sprengel, 
the current of 2400 cells would not pass, and 3600 only gave a faint blue glow 
which pervaded the whole tube with indications of strata 2 inches broad, 
which the rotating mirror showed to be flowing towards the negative. 
Air having through inadvertence been allowed to enter the tube, it was 
refilled with hydrogen and again exhausted. 
Tube 129, 2nd Charge of Hydrogen. 
9. — Pressure 16 m.m., 21,053 M. 4800 cells at first passed, but it almost 
immediately afterwards required 8040 cells. The ring being positive, 
curiously formed luminous entities shot at intervals from it, remained 
stationary for a time, and then disappeared, to be replaced by others : the 
flow, as seen in the mirror, was towards the negative. The phenomena are 
depicted in 1, fig. 43. 
The ring positive was illuminated with a red glow, the luminosities being 
bluish grey. 
10. — Pressure 15 m.m., 19,737 M, 8040 cells. The luminosities produced are 
* The tube having been subsequently re-attached to the pump when the McLeod gauge was in 
connexion with it, the phase was reproduced at a pressure of OT57 m.m., 207 M, 2400 cells, 
0. 0-01047 W. 
j The phase was subsequently reproduced at a pressure of 0'046 m.m., 61 M, C. 0‘00681 W, 
