184 
MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
scarcely be exposed long enough in consequence of the screw -like motion 
of the tongues. This motion appeared to be from positive to negative.* 
On mtroducing 900,000 ohms resistance, (C.) 0 '00341 4 W, the tongues 
grouped themselves in pairs, of which there were 40, and changed 
from blue to pink. Examined with the spectroscope the line C had 
disappeared. The tube was connected with the condenser of 42 '8 micro- 
farads and 3240 cells, a resistance of 200,000 ohms being in circuit, 
(C.) 0'007461 W, the apparatus was arranged as in fig. 26, Part I. At the 
full potential, the same spiral series of blue tongues, quite steady, was 
produced, and these made a complete rotation in 30 seconds. On breaking 
connexion between the battery and condenser, the strata gradually changed 
to pink as the charge of the condenser ran down through the tube. A. 
break-contact (direct) current was observed with the galvanometer in con- 
nexion with the secondary wire of coil 819, through the primary of which 
the current was made to pass ; this tending to show that there was a 
pulsation of rapid decrease and gradual increase of flow through the tube. 
Tube 129, 6th Charge of Hydrogen. 
63. — The tube, at 0'9 m.m., was partially charged with hydrogen by letting in 
4 small calibrated charges, which increased the pressure each time 1'4 m.m., 
pressure 6 '5 m.m., 8684 M, the resistance of the tube was found to be 
170,000 ohms, and the total resistance of the whole 8040 cells, 130,000 ohms, 
or an average of 16 '6 per cell. With 6960 cells the current, through the 
tube alone, was 0 '02456 W, and there were produced 9 luminous entities as 
shown hi fig. 5, Plate 15, taken from a photograph obtained in 1^ second. 
64. — The gas in the tube at the same pressure, namely 6'5 m.m., 8040 cells, 
C. 0'02634 W. There were 7 entities as depicted in fig. 4, Plate 15, copied 
from a photograph obtained in one second. 
65. — Pressure 6 '5 m.m., on the introduction of 300,000 ohms resistance with 
8040 cells, C. 0'0138 W, making a total resistance, inclusive of the tube 
and the battery, of 600,000 ohms, two luminosities were produced as seen 
in fig. 2, Plate 15, taken from a photograph obtained in two seconds, 
which, however, had to be corrected from a drawing, as there was a slight 
movement in the luminosities. 
* De la Rive (Geneve Mem. Soc. Pliys. xvii., 1863, p. 72) describing tke appearance of a nitrogen 
tube, says : “ ces stries semblent former une helice animee d’un mouvement de rotation autour de son axe.” 
Quet (‘Comptes Rendus’, xxxv., pp. 949-952) remarks tbat tbe apparent undulations and rotations 
of tbe strata vanish when single discharges are examined separately ; the strata are then seen to have a 
fixed position throughout the entire column. [These phenomena are, however, distinct from that of 
experiment 62. D. and M.] 
