The Effect of the Electric Discharge on Water VaiJour. 
147 
Thus :— 
Pressure under which Vapour 
was admitted. 
Maximum Pressure of Gas 
produced. 
2-6 mm. 
0-340 mm. 
12-0 (Sat. press.) 
4-0 
7- 1 
8- 0 
8-8 
10-0 
0-306 
0-354 
0-41 
0- 44 
1- 08 
2- 85 
The time taken for the pressures to attain to their maximum values 
increased as the pressure under which the vapour was admitted became 
greater — a result to be expected, for the more water vapour is initially 
introduced the greater will be the hindrance to diffusion of the gas 
produced through the apparatus, and, consequently, the longer will be the 
time for a state of equilibrium to be set up. The temperature during 
these observations was in the neighbourhood of 14° C, but not particularly 
constant. 
A series of experiments was made to determine how these maximum 
pressures, in addition to depending on the pressure under which the 
vapour stood initially in the apparatus, depended on the temperature. 
These experiments were conducted with a new tube, similar in construc- 
tion to the last, although differing slightly in its dimensions. The 
renewal of the tube was necessary owing to the breaking down of the 
previous one, due, presumably, to its perforation by the discharge. The 
gases from the walls of the tube were driven out as before ; and, as 
before, a belt of colour again formed near the centre of the tube during 
the process. Experiments identical with those conducted with the 
previous tube were made, and served to confirm the previous results. The 
maximum pressure of gas formed increased with the pressure under which 
vapour was introduced, up to the point of disappearance of the coloration. 
In this case, however, it was necessary to pass the discharge through 
vapour under 4 mm. pressure before the last traces of colour completely 
vanished. Also, as before, when the pressure under which the vapour was 
admitted was less than 4 mm., the pressure of gas formed, after reaching 
its maximum value, diminished at a decreasing rate ; i.e., provided some 
coloration was present, the maximum pressures of gas formed was followed 
by a diminution at a decreasing rate. Curves 15, 16, 17, 18, 19, 20 show 
how the pressure of gas formed by the passage of the discharge varied 
with the time, when the discharge was passed through vapour under 
various pressures up to 4 mm. 
