314 
Transactions oj the Royal Society of South Africa. 
factors — (1) the number (M) of rapidly moving corpuscles produced from 
the atoms of the gas ; (2) the number (k) of pairs of ions each corpuscle 
produces before its energy is entirely spent. The observed effect is that 
of ]cM. Identifying the corpuscles produced from gaseous atoms as 
observed by the writer with those produced from gold leaf in contact 
with the gas, the relative values of M can be found by dividing A;M b^ 
the co-efficients k. These results are given in the fourth column of 
Table I. It is at once apparent that, although the whole ionisation by 
X-rays is not an atomic phenomenon, yet the actual number of atoms 
originally ionised is atomic, and the much-debated anomaly of the relative 
ionisation and absorption of SHg and SO.,* is not explained away entirely,, 
for we still have to explain how the state of combination of the atoms 
affects the number of ions produced by a single corpuscle. 
Table IL 
Element. 
Atomic 
weight. 
Atomic 
number. 
A.C.E.f 
ACE. 
(At.Avt.)-* 
V 10-'' 
A.C.E.t 
(At-No.)-* 
A.C.E. ^10-^ 
H 
1 
1 
•0005 
•20 
C 
12 
6 
•2 
•17 
10^3 
•76 
N 
14 
7 
•34 
•385 
11-3 
•62 
0 
16 
8 
•62 
•625 
10-4 
•65 
8 
32 
16 
10-9 
11^0 
9^6 
•60 
CI 
35-5 
17 
14-7 
10^8 
•57 
The values of M clearly indicate that the number of rapidly moving 
corpuscles (3 particles) produced is an atomic effect, e. g. : 
0., = l-25 SO, = 12-2 S=:ll 
H,= ^00561 SH,=:1105 .-. S = 11. 
Table II is partly taken from Moore's t work on this subject. The 
column A.C.R.f he calls the Atomic Corpuscular Eadiation, which indicates 
the relative number of rapidly-moving /3 particles produced from equal 
numbers of atoms of the respective elements. The numbers were obtained 
in the manner I have indicated after dividing the full ionisation (k M) by 
Barkla and Philpot's values of Jc. The column A.C.R. should be similar to 
Moore's ; these results are obtained from ionisations observed by myself and 
others using the simple gases. Moore, for the most part, used organic 
vapours. In his paper he clearly showed that the atomic corpuscular radia- 
tion, which I have called the direct ionization, is proportional to the fourth 
power of the atomic weight of the elements from which it originates. This 
result is very important, for, as 0. W. Richardson points out (Electron 
* Barkla and Simons, Phil. Mag. (6) xxiii, p. 319. 
t Loe. cit. 
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