PRODUCED IN GASES BY RClNTGEN RAYS. 
229 
determinations for hydrogen are less accurate, and so results were obtained for small 
values of T, only because of their greater importance, and in order to expedite the 
readings. 
The results are represented by I. and II. of fig. 17. 
The lines projected to T = 0 indicate for the uncorrected velocity of the negative 
ions 7'3 centims. per second, and for the positive ions 6 *2 centims. per second when 
under a pressure of 76 centims., and at a temperature of about 20° C. These values 
are for dry hydrogen containing 3 A per cent, of air. The correction for the presence 
of the air can be found approximately by finding the value of the velocity in a gas 
having a larger percentage of air. 
Fig. 17. 
The following are a number of results obtained with dry hydrogen which contained 
14 A per cent, of air :— 
Table XX.—Dry Hydrogen with 14 A per cent, of Air. 
Reference 
number. 
X. 
U. 
A. 
T. 
Tempera¬ 
ture. 
Gas 
pressure. 
Ionic \ 
Negative. 
elocity. 
Positive. 
1 
2-95 
20A 
+ 9-62 
•15 
°C. 
21-2 
76-3 
3-70 
2 
2-95 
20-2 
-8-28 
•15 
21-2 
76-3 
4-25 
— 
3 
2-95 
18-6 
-7-59 
•16 
22 
76A 
4-27 
— 
4 
2-95 
18-6 
+ 8-90 
•16 
22 
76A 
3-65 
