PRODUCED IN GASES BY RONTGEN RAYS, 
213 
The following set of readings was taken for the negative ions in dry air :— 
Temperature = 15*8° C. X = 2'60 centims. Barometer = 76 centims. 
Excess pressure in gasometer = l’O centim. 
,, ,, „ apparatus = T3 centim. 
7 cells = 14'5 volts. 
Fig. 7. 
Table V. — Dry Air. Negative Ions. 
Voltage of outer 
Electrometer deflection 
Descent of gasometer 
cylinder. 
in 30 seconds. 
in 40 seconds. 
Cells. 
Divisions. 
Centims. 
-2 
141-5 
2-07 
-3 
87 
2-05 • 
-4 
28-5 
2-08 
-5 
6-5 
2-05 
-4'4 
18 
2-08 
-3-4 
63 
2-05 
-2-4 
116 
2-05 
The results are shown graphically in Curve II. of fig. 7. 
U corrected for pressure = 7'64 centims. per second. 
A = 9‘21 volts. 
