ELECTRIC DISCHARGE WITH THE CHLORIDE OF SILVER BATTERY. 211 
Photograph. 
Distances 
between terminals, 
inches. 
Ratio of 
distance. 
Current 
W. 
Ratio of 
current. 
a 
7 
1-00 , 
0-00912 
1-29 
b 
13 
1-86 
0-00858 
1-22 
■ c 
19 
2-71 
0-00858 
1"22 
cl 
25 
3-57 
0-00807 
1-14 
e 
31 
4-43 
0-00834 
1-18 
f 
37 
5-29 
0-00782 
111 
g 
43 
6-14 
0-00756 
1-07 
h 
49 
7-00 
000706 
1-00 
The representations given in Plate 1 7 show the number of strata in each case ; 
they are copied from photographs obtained in succession. The resistances 
of the tube for the several distances between the terminals are given in 
page 164. When the primary of coil 819 was in circuit, as fig. 69, page 227, 
the advent or retreat of a stratum produced a deflection of the galvanometer 
in connexion with the secondary of the coil, thus indicating a pulsation in 
the current. 
We have already stated * that the discharge is frequently flowing and unsteady, 
but that perfectly steady strata may be produced by properly regulating the current by 
the gradual introduction of resistance in the circuit.! In Plate 17 we give three cases 
by way of example, thus : — 
Tube 73, 22*5 inches between the two straight terminals, diameter 1'5 inch, C 2 H 6 . 
204. — 4800 cells, C. 0'00731 W, produced an agitated discharge throughout 
almost the whole length of the tube, there being only four strata, as shown 
in fig. 2, a, Plate 17. By the introduction of 200,000 ohms the current 
was reduced to 0'000408 W, and then perfectly steady strata were produced, 
as in b of the same figure. These are copied from photographs obtained 
in 20 and 30 seconds respectively. 
* ‘ Comptes Rendus,’ xvi., 686, and xvii., 746, 1875. 
Quet (‘Comptes Rendus’, xxxv., 949-952) tried by shifting the positive terminal to drive it into 
the dark space near the negative. He found he conld extinguish the positive light in air at atmospheric 
pressure, but not in rarefied gas. 
f Gassiot (Proc. Roy. Soc. 1872-3, p. 338) : “ No. 248. The discharge under certain conditions is 
continuous and under others it becomes intermittent. These conditions are, that without resistance intro- 
duced in the circuit, except that inherent in the battery, the discharge cannot be resolved by the rotating 
mirror, and so far must be considered continuous, but when a certain given and described resistance is 
introduced in the circuit the discharge becomes intermittent.” 
And at p. 339 : “ The form in figuration of the striae and the positions they occupy in the vacuum tube 
appear to depend on two separate and distinct conditions, 1st, the power and energy of the battery ; 
2nd, the state of tension of the highly attenuated matter through which the discharge is visible.” 
“ The striae can be controlled, their number increased or reduced, and their places or positions in the 
tubes altered by the introduction of measurable amounts of resistance in circuit.” 
2 E 2 
