448 
MR. C. T. 11. AVILSON 
ON THE CONi)EN8ATION NUCLEI PRODUCED IN 
Uranium Rays. 
For experiments on the inlliience of an electric held on the nuclei produced by 
Uranium-rays the aj)paratus constructed for the experiments on the nuclei arising 
from a zinc plate exj)osed to ultra-violet rays was used (hg. 11). A piece of thin 
sheet tin was sidrstituted for the zinc. A thin float, consisting of a sheet of cork 
wrapped in tinfoil, formed the lower plate of the condenser. On the up})er surface of 
this was placed a layer of moist uranium oxide. The thickness of the air layer was 
regulated by allowing some water to esca))e or drawing a little more into the cloud- 
vessel, according as an increase or diminution of the thickness was recjuired. 
The following results wei'e obtained. 
DiFnERENOE of })otential used == 240 volts ; thickness of air layer = 1 centim. 
' 
Result of expansion. 
Gauge reading (in mil- 
liras.) = j). 
1 
Upper plate positive. 
Upper plate negative. No E.iM.F. 
164 
0 
0 Fog 
184 
0 
0 Fog 
1 
'fhese experiments were many times repeated with the same results. The effect 
of the electric held was eijually marked when the distance between the plates was 
increased to 1‘3 centims. The dro})s produced wdiile the electric held was maintained 
were too few to l)e detected. All the nuclei })roduced by the action of the uranium 
appear therefore to be charged. 
Metals. 
The same ajjparatus was used, but the hoat was omitted and a j)olished zinc plate 
was substituted for the tin. The arrangements were in fact exactly the same as in 
the experiments on the nuclei produced ])y the action of idtra-violet light on zinc, 
Avith the omission of the apparatus necessary for producing these rays. The results 
obtained were entirely negative. 
