Fleating Eject of the Radium Emanation. 219 
time (after it has reached a maximum value) is given by 
t =F 
Outen 
Qo 
the total amount of heat given out from the emanation 
released from 1 gram of radium is equal to 
— 0 > 
At — Y 
Qoe ad t a tn 
0 
Since the heating effect of the emanation decays to halt 
value in about 3°73 “day s N='0077 when an hour is taken as 
the unit of time. The total amount of heat derived from 
the emanation from 1 gram of radium is thus about 10,000 
gram-calories. Now it has been shown (Rutherford, 
‘Nature,’ Aug. 20, p. 366, 1903) that the volume of the 
emanation released from 1 gram of radium probably lies 
between 6 x 10-4 and 6 x 10~° c.c., at standard pressure and 
temperature. The amount of heat liberated per hour from 
lc.c. of the emanation would thus lie between 1:25 x 1@ 
and 1:25x 10° gram-calories. This amount of heat from 
1 c.c. of the emanation would probably be sufficient to raise 
to a red heat, if not to melt down, the glass tube containing 
it. 
The emanation behaves as if it were a gas of heavy mole- 
cular weight. Assuming for the purpose of calculation that 
the molecule of the emanation is 100 times as heavy as the 
molecule of hydrogen, it can readily be deduced that 1 gram 
of the radium emanation, in its succession of changes, would 
radiate an amount of energy lying between 2x 10° and 
2x10 gram-calories. One pound weight of the emana- 
tion would initially radiate energy at the rate of 10* to 10° 
horse-power and, while the heating continued, would emit 
an amount of energy between 6x10 and 6x 10° horse- 
power-days. 
Quite independently of any assumptions, a result of the 
same order of magnitude can be deduced from the observed 
heating effect of the emanation, and the fact that the 
emanation has not, so far, been detected either by its volume 
or its weight. 
There is thus no doubt that matter under special conditions 
is capable of emitting an amount of energy enormous com- 
pared with that released in the most intense chemical re- 
actions. On the disintegration hypothesis (Rutherford and 
Noddy, Phil. Mag. May 1903) ) this energy is derived from 
the energy latent in the radium atoms, and is released in 
the successive stages of their disintegration. 
McGill University, Montreal, 
December 22, 1903. 
