288 
considering the energy of the recoil as equal 
and opposite that of the a particle, the energy 
of recoil of mass M is 3 uM MY?, therefore total 
: n a2 
energy is 3 mn[{l + at! >V2 + E where 
E is the energy of the 6 and ) rays absorbed under 
these conditions. 
1.38 x 10° ergs per second corresponds to heat 
emission of 118 grams calories per hour. 
Heating effect of emanations 94.5 calories per hour. 
Observed values 94 calories per hour; caleulated 94.5 
calories per hour. 
Rutherford and Robertson made an experimental determination to see 
how accurately this theoretical value harmonized with the experimental 
value and found a very close correspondence between the two values. This 
agreement led Rutherford to say that “there thus appears to be no doubt 
that the heat emissions of radium can be accounted for by taking into 
consideration the energy of the radiations absorbed.’ (The heat emitted 
is 2.44 x 10° calories per gram). ; 
He gives an interesting comparison as to the amount of energy set free 
in the action accompanying the expulsion of the rays, as follows: “‘the 
heat emitted during the combination of 1 ec. of H and O to form H,0O is 
about 2 gram calories; the emanation during its successive transformations 
thus gives out more than ten million times as much energy as the com- 
bination of an equal volume of H and O to form water although the latter 
reaction is accompanied by a larger release of energy than that of any other 
known to chemistry.” 
Further, ‘“‘the energy emitted by radioactive substances is manifest during 
the transformation of the atom and is derived from the initial energy of the 
atoms themselves. The enormous quantity of energy released during the 
transformation of active matter shows unmistakeably that the atoms them- 
selves must contain a great store of internal energy; ‘“‘undoubtedly this is 
true of all but it is only perceived in the case of those which undergo atomic 
transformation.” 
Experiments conducted within the past three years at Munich in determ- 
ining the interference effects produced by the passage of X-rays through 
crystalline substances have shown that X-rays possess many of the properties 
