. 
Transformation Products of Radium. 639 
interval of two months over which the observations have 
extended. 
Some results indicate that this steady increase with time 
continues for at least nine months. The emanation from 30 
milligrams of radium bromide was condensed in a glass tube, 
which was then sealed. After a month’s interval the tube 
was opened, and dilute sulphuric acid introduced. The acid 
dissolved the active residue deposited in the tube. On 
driving off the sulphuric acid by heat, a radioactive deposit 
was obtained. The first determination of the activity of this 
residue was made about six weeks after the introduction of the 
emanation. The activity eight months later was found to be 
about seven times the initial value. The results could not be 
very accurately obtained, as a portion of the activity had 
been removed in the interval by a bismuth rod placed in a 
solution of the active matter. The result, however, indicated 
that the activity had steadily increased over a period of nine 
months. 
Radiations from the Active Matter. 
The residual activity consists of both aand 8 rays, the latter 
being present initially in an unusually large proportion. The 
proportion of a to 8 rays from the platinum plate, one month 
after removal, was at the most one fiftieth of that from 
a thin film of radium bromide in radioactive equilibrium. 
Unlike the @ ray activity, the activity measured by the 
8 rays remains constant, and, in consequence, the proportion 
of a to B rays steadily increases with the time. The experi- 
ments showed that the intensity of the @ rays did not vary 
much, if at all, over a period of nine months. The want of 
proportionality between the « and 8 rays shows that the two 
types of rays arise from different products. This conclusion 
is confirmed by experiments, now to be described, which 
show that the products giving rise to @ and @ rays can 
be temporarily separated from one another by physical and 
chemical means. 
} Effect of Temperature on the Activity. 
An active platinum plate was exposed to varying tem- 
peratures in an electric furnace, and the activity tested after 
exposure at atmospheric temperature. Four minutes’ ex- 
posure in the furnace, at first at 430° C., and afterwards at 
800° C., had little, if any, effect on the activity. After four 
minutes at 1000°C. the activity decreased about 20 per cent., 
and a further exposure of eight minutes at a temperature of 
about 1050° C. almost completely removed the @ ray activity. 
2¥2 
