198 
MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
Tube 132, 2nd Charge of Hydrogen. 
161 . — After repeated exhaustions, fillings, and re-exhaustions the pressure was 
reduced to 19 m.m., 25,000 M. With 8040 cells there was an intermittent 
flash of light through the tube, whether the point or ring were positive. 
162. — Pressure 11 '8 m.m., 15,526 M. Three worm-like luminosities with 8040 
cells. 
163. — Pressure 7‘ 8 m.m., 10,263 M, 8040 cells. Eight luminosities as depicted in 
12, fig. 53. 
164. — Pressure 6’2 m.m., 8158 M, 8040 cells. 12 very similar luminosities, but 
on introducing 500,000 ohms into the circuit they changed to arrow- 
headed entities, as 14, fig. 53 ; the introduction of 1,000,000 ohms changed 
them into parallel worm-like entities, 15, fig. 53. With 4,500,000 ohms 
resistance all the luminosities disappeared, a nebulous light reaching from 
the positive half-way towards the negative, the interval between it and the 
negative being quite free from light. This nebulous light shrank in a few 
seconds up to the positive and disappeared, leaving a faint glow on the 
positive terminal. The above description will render evident how great a 
variety of phenomena may be produced by varying the current through a 
tube at a constant pressure. 
165. — Pressure 4 - 5 m.m., 5921 M. The current of 5640 passed: both with this 
number, and with 8040 cells the same phenomena were produced without 
external resistance, namely thirteen beautiful blue luminosities as 17, fig. 53, 
agitated near the positive, but perfectly steady in other parts of the tube. 
With 8040 cells and 800,000 ohms resistance, a series of small arrow-headed 
luminosities arranged -themselves in a spiral, as 18, fig. 53. Unfortunately 
this beautiful tube was spoiled by the accidental breaking off of one of the 
glass stop cocks, and, though since mended, it has not been refilled, the 
pumps being required for other work. 
' Tube 148, Hydrogen. 
Length 32'5 inches, distance between the terminals 28'5 inches, diameter 1 ‘75 inch. 
166. — Pressure 18 m.m., 23,684 M, 8040 cells. A tell-tale tube, No. 82, placed 
in circuit, so as to indicate a current by its illumination, before a visible 
glow occurred in the large tube. 8040 cells, a current too small to measure, 
and evident only in the tell-tale tube. 
167. — Pressure 10 - 5 m.m., 13,816 M, 8040 cells, C. 0'00580 W. Three luminosities 
with arrow heads arranged in a spiral, like 14, fig. 53, which in a few 
minutes settled down to one entity, with the characteristic form shown in 
3, fig. 50, in the case of tube 139, at a pressure of 12 m.m. There was 
