210 
MR. J. ZELENY ON THE VELOCITY OF THE IONS 
From equation (10) 
T = ^ = '10 second. 
U 25'2 
The following is a set of readings taken for negative ions in moist air. Unless 
otherwise mentioned the values of «, b, and the width of the beam of rays will 
hereafter be taken the same as in the previous example. 
Temperature = 147° C. X = 6 ’42 centims. Barometer = 747 centims. 
Excess pressure inside gasometer = 1*54 centims. of mercury. 
„ ,, in apparatus = ‘59 centim. of mercury. 
8 cells = 16*5 volts. 
Table II.—Moist Air. Negative Ions. 
Voltage of outer 
cylinder. 
Electrometer deflection 
in 30 seconds. 
Descent of gasometer 
in 40 seconds. 
Cells. 
Divisions. 
Centims. 
-4 
128 
6-05 
-5 
68-5 
5-95 
-57 
45 
5-94 
-6 
17-5 
5-92 
-5-6 
32-5 
5-89 
-5-2 
50 
5-90 
-6 
18 
6-02 
-57 
44-5 
5-99 
-5 
67-5 
5-96 
-47 
95 
5-90 
- 7- 
2 
5-90 
The results are represented in Curve II. of fig. 5. 
U = 22T centims. per second. 
A = 127 volts. 
227 
v — 5718 -—— = 1*39 centims. per second. 
672 x 127 1 
The pressure in the apparatus = 7 5’3 centims. 
The velocity reduced to 76 centims. pressure = 1'38 centims. per second. 
672 
T = = ‘29 second. 
The following is a summary of the results obtained for moist air for both the 
positive and negative ions. Each result was obtained from a series of observa¬ 
tions as indicated by the above examples. The results are reduced to 76 centims. 
pressure. 
Letters refer to quantities in equations (9) and (10). 
