182 
MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
phenomena, but had merely taken observations of the deflections of the 
galvanometer with the batteries short-circuited, thus : — 
May 25th, 1876, 3240 powder cells 
Aug. 4th, „ ,, ,, ,, 
May 25th, ,, 2400 rod ,, 
Aug. 4th, „ 4800 ,, 
gave C. 0'03251 W. 
„ „ 0-03858 „ 
„ „ 0-12200 „ 
„ „ 0-10410 „ 
8040 powder and rod cells „ ,, 0*04901 „ 
Tube 129, 5th Charge of Hydrogen. 
45. — A glow at both terminals was first seen when the pressure was 17 "2 m.m., 
22,632 M, with 8040 cells, and great heat developed in the dark discharge near 
the middle of the tube. The spectroscope showed faintly the C and F lines. 
46. — Pressure 16 5 m.m., 21,710 M, 8040 cells current. 1 luminosity like that 
on the right hand of 5, fig. 43, shot out from the positive and approached to 
within 6 inches of the negative, then receded back and disappeared. 
47. — Pressure 15’8 m.m., 20,789 M, 8040 cells. 3 luminosities, very steady, 
like 5, fig. 43, which moved slowly and steadily towards the negative. The 
tube hottest in dark part where there was probably a non-luminous entity. 
48. — Pressure 14 m.m., 18,421 M, with 6840 cells, the current was unsteady, 
but it was perfectly steady with 8040, and 6 arrow-headed luminosities like 
that on the left of 107, fig. 46, were produced and soon disappeared. 
49. — Pressure 10 - 3 m.m., 13,552 M, with 8040 cells. 8 luminosities something 
like 1, fig. 43. 
50. — Pressure 9"4 m.m., 12,368 M, with 8040 cells. 12 luminosities like those, 
fig. 7, Plate ] 5. The C and F lines seen in the glow around the negative. 
51. — Pressure 7 "7 m.m., 10,132 M, with 8040 cells. 10 luminosities like fig. 6, 
Plate 15, these ran together and disappeared and reappeared in a few 
seconds. 
52. — Pressure 6"6 m.m., 8684 M, with 8040 cells. 12 luminosities very similar 
to those shown at fig. 5, Plate 15, the last adhering to the positive. The 
C line not visible in a nebulosity with the spectroscope, but that and the 
F line were both to be seen in the glow around the negative. 
53. — Pressure 5’9 m.m., 7763 M, 8040 cells, C. 0-02056 W. 13 luminosities 
like those fig. 6, Plate 15. With 100,000 ohms, C. 0-01390 W, there were 
10 luminosities not so wide as those when there was no resistance. 
54. — Pressure 6T m.m., 8026 M, 8040 cells, C. 0-01910 W. At first 13 lumi- 
nosities a little unsteady, then llijr perfectly steady, like fig. 6, Plate 15. 
F and C visible in the glow around negative. F was not visible in a 
luminosity. 
