194 
MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
seconds. The strata altered in form, afterwards becoming like 22, fig. 50, 
the convex face being green, the middle blue, and the concave face reddish. 
The C and F lines were seen with the spectroscope directed on the glow 
around the negative. 
133. — Pressure 0'3425 m.m., 451 M, 2400 rod cells, C. 0'01272 W. Strata like 
those in tube 129, a, fig. 43, obtained with a pressure estimated at 0'2 m.m., 
263 M, but which we had not then the means of measuring. With 200,000 
ohms resistance current was reduced to 0'00580 W. 
134. — Pressure 0'2608 m.m., 343 M, 2400 cells, C. 0'01102 W. A phase produced 
as shown in fig. 8, Plate 16, copied from a photograph obtained in 40 seconds. 
135. — Pressure 01204 m.m., 158 M, 3600 cells, C. 0'0l77l W. A phase as shown 
in fig. 10, Plate 16, copied from a photograph obtained in 27 seconds. 
136. — Pressure 0T103 m.m., 145 M, 3600 cells, C. 0'01575 W. A phase of 23 
strata as shown in fig. 9, Plate 16, copied from a photograph obtained in 15 
seconds. 
137. — Pressure 0'051 m.m., 67 M, the current of 3600 cells passed intermittently; 
4800 cells, C. 0'00191 W, produced a continuous illumination from the positive 
to within 3 inches of the negative, the discharge at the negative licking the 
inside of the tube as in fig. 11, Plate 16. 
138. — Pressure 0'01 m.m., 13 M, the current of 4800 rod cells just passed : with 
6960 cells the current produced no appreciable deflection of our galvanometer 
which would indicate 0 '00024 W. The strata, it will be perceived, have 
thickened and become much wider as shown in fig. 11, Plate 16, copied from 
a photograph obtained in 7 seconds. The discharge at the negative licked 
the side of the tube and was very sensitive to the approach of the finger. 
139. — By standing 16 hours the pressure had somewhat increased without leakage 
having occurred, and was 0'037 m.m., 49 M, 6960 cells, current less than 
0'00024 W; the discharge was milky white and quite different from anything 
before seen with a hydrogen residual charge. The strata had become still 
broader, as seen in fig. 12, Plate 16, copied from a photograph, the negative 
discharge hugging the tube and being very sensitive to the finger. The C 
and F lines could not be seen with the spectroscope, but there was a double 
green line near b. 
140. — A charge of hydrogen was let in, being the contents of the india-rubber 
tube between the glass cock on tube 139, and the cock on the four-way 
junction-piece, F, fig. 35 ; the charge was 0'00l725 of the capacity of the 
tube and pump, and increased the pressure to 1*311 m.m., 1725 M. 3600 rod 
cells produced a stratification composed of umbrella-shaped strata, united 
in the middle of the tube by a luminosity one-third the length of the tube. 
The double green line near b had disappeared and the C, F, and G lines 
were visible in the spectroscope. 
