216 
Mr Campbell, The ft Rays from Potassium . 
Summary. 
§ 1. The object of the experiments is to prove that the ra) r s 
from potassium carry a charge and that, since their high pene- 
tration forbids the conclusion that they are a rays, they are ft rays. 
§§ 2 — 4. After preliminary attempts to observe the magnetic 
deflection of the rays the method is abandoned in favour of the 
electrostatic deflection. Incidentally it is proved beyond doubt 
that the potassium rays can affect a photographic plate. 
§§ 5 — 6. The apparatus used is described. 
§§ 7—11. The results show clearly the effects of a deviation 
of the rays in an electrostatic field and confirm the conclusion of 
an earlier paper that the potassium rays are ft rays of an average 
velocity less than that of the ft rays of uranium. 
