432 
passed in a single red stream, but without bands. At 0:04 
the spherical strata and the rotation were admirably developed. 
It was especially beautiful when the ball was positive. The 
blue hemisphere on the point was surrounded by a dark shell, 
whose projection on the disc looked like a black ring. Round 
this was a pink one, which folded round the disc, and formed 
the cone already described. In this also were bands, which, 
at the part which bent round the edge, looked like fiery 
spikes. I have never seen stratification in the blue light. 
**13. Vacuum of coal gas, which had been passed through 
sulphuric acid, 0:03, Smee, point positive; the light was 
bright green; pink stars on the point; lilac shell on ball. 
The strata were very fine, but flattened on each side of the 
axis ; there also were broad secondary bands, as in (9), which 
sank down like waves. The ball, when positive, was wrapped 
in a luminous haze, and covered with green stars; others 
were on the point. After a few seconds the strata became 
faint. There was barely a trace of fluorescence with.the 
platino-cyanide. 
“14, Air vacuum 0':025, Smee. With the point positive 
the strata were very distinct at first, but soon faded: there 
were also the broad shadowy bands which ¢his time rose. 
Stopping the action of the battery for 60s, the strata re- 
appeared : once or twice the light reached the ball, without 
any intervening dark space. When the point was negative, 
the glass dise was covered with circular rings, which con- 
tinued round its edge and down the cone, as in(11) and (12), 
with higher electric power, but less exhaustion. 
«© 15. With hydrogen vacuum 0'*12, and two Groves, the 
electrodes being a half-inch ball screwed into the pump-plate, 
and a brass plate closing the top of a tall receiver, with a dis- 
tance of 17: between them, there was scarcely any stratifica- 
tion. This was also the case with the air vacuum; but when 
the distance was only 5'-5, they had their usual character, and 
were very distinct. 
