ELECTRIC DISCHARGE WITH THE CHLORIDE OF SILVER BATTERY. 163 
Tube 
Started with 
Ban up to 
Nature of the Gas. 
1 
200,000 
250,000 
o 
350,000 
500,000 
3 
400,000 
(decreased) 
4 
90,000 
110,000 
5 
170,000 
290,000 
6 
270,000 
500,000 
N 
7 
170,000 
370,000 
8 
50,000 
60,000 
9 
70,000 
CO, 
10 
150,000 
16 
450,000 
500,000 
18 
62,000 
22 
500,000 
25 
50,000 
80,000 
31 
35,000 
40,000 
32 
37,000 
35 
15,000 
17,000 
37 
54,000 
41 
32,000 
42 
15,000 
70,000 
N 
56 
40,000 
45,000 
62 
102,000 
140,000 
H 
71 
80,000 
130,000 
Cy 
81 
150,000 
infinity. 
co 2 
83 
190,000 
H 
93 
over 1,000,000 
co 2 
94 
700,000 
I 
95 
700,000 
1,000,000 
Si PI, 
Subsequently we found it to be more convenient not to make special determinations 
of the resistances of the tubes beforehand in the way just described, but to obtain 
them by reproducing the deflection of a galvanometer, or by measurements taken 
with an electrometer in the manner described in pp. 165-167, while observing the 
phenomena of stratification. We not only save time in this way, but obtain the 
resistance at the actual moment of the occurrence of any particular phase. 
From measurements thus made with a tube having several wires about 1 inch 
apart (No. 25, fig. 37), or a Spottiswoode tube* with a shifting terminal (No. 147, 
figs. 39 and 40), we found that the resistance of a vacuum tube, unlike that of a wire, 
does not increase in the ratio of the distance between the terminals for the same 
gas at the same pressure.! 
* Recently, by permission of Mr. Spottiswoode, we Have had made tube Ho. 147, with the ingenious 
arrangement, suggested by his assistant Mr. P. WarS, of a movable terminal, attached to a spiral of fine 
copper wire, which permits of its being brought into actual contact with the opposite terminal, or placed 
at any required distance from it; this tube is marked out into eight equal spaces by slips of paper 
pasted outside. 
t Hittorf (Pogg. Ann. exxxvi., 1869, pp. 1-31 and 197-234) devised several experiments to show that 
Y 2 
