Iv | NATURE OF THE RADIATIONS 143 
98. Connection between absorption and density. The 
absorption constant »X of the rays was determined from the 
een A 
equation — =e” for screens of different materials. On account 
I, 
of the small absorption in water and glass it was difficult to 
determine ® with accuracy. 
The results are included in the followmg table :— 






an B rays from 
Vas uranium 
Substance 
r | r 
r a r ESN 
density density 
Water ca 033 033 = a 
Glass see 086 035 14:0 5°7 
Toni Be 28 036 44 I) 1536 
Zine... Noa 28 039 == f= 
Copper es “31 ‘035 GO |p eee 
clini bee 38 052 96 13°2 
Lead eA Ue) | Ws 122 10°8 
Mercury ... ‘92. | -068 — = 






On the right is added a comparison table for the 8 rays given 
out by uranium. It will be seen that the quotient of absorption 
by density is in neither case a constant, but the differences are 
no greater for the non-deviable penetrating rays than for the devi- 
able rays of uranium. It is interesting to observe that the value 
of X divided by the density is, for both types of rays, twice as great 
for lead as for glass or iron. 
It will be seen from the above table that the penetrating rays 
from radium compared with the deviable rays of uranium pass 
through a thickness of glass about 160 times greater for the same 
reduction of intensity. 
99. Nature of the rays. In addition to their great pene- 
trating power, the y rays differ from the a and @ rays in not being 
deflected to an appreciable amount by a magnetic field. 
It now remains to consider whether the rays are material in 
nature or whether they are a type of ether-pulse like Réntgen 
rays. In some respects the y rays seem more closely allied to 
