ELECTRIC DISCHARGE WITH THE CHLORIDE OF SILVER BATTERY. 
177 
external resistance there were 10 very broad strata which extended from the 
positive to within 5 inches of the negative ; the discharge at the negative 
was tri-furcated. The phenomena are shown in 24, fig. 45. 
27. — At the 14th cistern-full the current of 6960 cells would not pass at first, 
but, after the charge of 8040 had been sent through, 5880 were sufficient. 
With 500,000 resistance 8 strata were produced as in 24, fig. 45. With 
8040 cells the broad strata were crossed by bright lines not more than O'l 
inch apart. On the end of the central point of the negative discharge there 
was produced a pink half hour-glass addition, the point of which joined onto 
it at the centre of the ring. The two points of the negative discharge close 
to the tube were very sensitive to the approach of the finger.* 
28. - — At the 16th cistern-full it required 6960 cells to pass at first, but after- 
wards the tube became hot, I and the current of 2400 passed, the discharge 
taking place most readily when the point was negative. The phenomena were 
as in 20, fig. 45. The flow was from positive to negative. 
29. — At the 17th cistern-full 5880 cells passed, but 6960 gave the best effect : 
9 strata like 24, fig. 45, slightly pink, near the negative. The F line was 
seen with the spectroscope. A slow flow from the positive was seen with the 
rotating mirror. The next day the current of 2400 cells passed, producing 
a confused stratification ; 3600 produced a more steady one. The nega- 
tive discharge left the centre of the ring and hugged the side of the 
* In his ‘Notice snr l’appareil d’induction de Ruhmkorff, et les experiences qn’on peut faire avec cet 
instrument, 8 me edition, Paris, 1857,’ Dtr Mono el claims to have been the first to announce the 
attraction of the luminous discharge to the wall of the vacuum chamber when this is touched by the 
finger. Quet et Sequin (‘ Comptes Rendus,’ xlvii., 1858, pp 964-967) describe the effect of approach- 
ing the hand or a ring of tinfoil to a vacuum tube : the bright strata widen out on that side of the hand or 
tinfoil which is towards the positive terminal, and at the edge of the tinfoil, on the same side, a large 
dark space occurs — the phenomenon being best seen when the hand or tinfoil is near the positive terminal ; 
on sliding the hand towards the positive the strata re-enter each other, but on sliding the hand from the 
positive they issue out again. Gassiot (Brit. Assoc., Aberdeen, vol. xxix. (sect.), p. 155), in speaking of 
strata being very sensitive to the finger in a cylinder 4^ inches in diameter and with the terminals 
20 inches apart, says : “ On the four fingers being placed in succession on the stratification they dis- 
appear in succession, and may be separated to a considerable distance by placing both hands on two 
separate portions of the cylinder.” 
t Frequently during the course of experiments with the tube 129 and others, when highly exhausted, 
it has required many cells to pass in the first instance, but when the tube had become heated a much 
smaller number sufficed. 
Gassiot has also found that warming the tube promotes the passage of a current, and with regard to 
very low temperatures makes the following statement (Phil. Trans., 1859, p. 146) : — “ In a Torricellian 
vacuum which gave good cloud-like strata no change occurred when cooled to +32° Fah., but at 
— 102 c Fah. all traces of strata disappeared as well as the red glow around the negative ; a glow 
throughout the tube remained. On heating the tube to the boiling point of mercury +600° Fah. the 
strata were likewise destroyed. When the mercury was frozen the stratifications disappeared, but a 
magnet made them reappear.” 
MDCCCLXXVIII. 2 A 
