222 The Nature of the Emanations from Radium. 
may be hundreds, or thousands, or millions of times as many 
as those of atoms of ‘ ordinary material.’ 
But this leaves THE mystery of radium untouched: Curie’s 
discovery that it (perpetually ?) emits heat at a rate of ahout 
90 Centigrade calories per gramme per hour. If emission 
of heat at this rate goes on for little more than a year, or, say, 
10,000 hours (134 months), we get as much heat as would 
raise the temperature of 900,000 grammes of water by 1° CO. 
It seems to me utterly impossible that this can come from a 
store of energy lost out of the oramme of radium in the 
10,000 hours. It seems to me therefore, absolutely certain, 
that if emission of heat at the rate of 90 calories per gramme 
per hour found by Curie at ordinary temperatures, or even at 
the lower rate of 88 found by Dewar and Curie from a spe- 
cimen of radium at the temperature of liquid oxygen, can go 
on month after month, energy must somehow be supplied from 
without to give the energy of the heat which gets into the 
material of the calorimetric apparatus. 
_I venture to suggest that somehow etherial waves may 
supply energy to the ‘radium while it is giving out heat to the 
ponderable matter aroundit. Think of a piece of black cloth 
hermetically sealed in a glass case, and sunk in a glass vessel 
of water exposed to the sun; and think of another equal and 
similar glass case containing white cloth, submerged in an 
equal and similar glass vessel of water, similarly exposed to 
the sun. The water in the former glass vessel will be kept 
very sensibly warmer than the water in the latter. This 
is analogous to Curie’s first experiment, in which he found 
the temperature of a thermometer, with a little tube containing 
radium kept beside its bulb, in a little bag of soft material, 
to be permanently about 2° C. higher than that of another 
equal and similar thermometer, similarly packed with a little 
glass tube not containing radium beside its bulb. 
By observing the temperature of the water in our two 
glass vessels, a calorimetric investigation might be made, 
showing how much heat is given out per hour by the black 
cloth to the surrounding glass and water. Here we have 
thermal energy communicated to the black cloth by waves of 
sunlight, and given out as thermometric heat to the glass and 
water around it. Thus, we actually have energy travelling 
inwards through the water, in virtue of waves of light, and out- 
wards through the same space in virtue of thermal conduction. 
My suggestion respecting radium may be regarded as 
utterly unacceptable ; ; but at all events it will be conceded 
that experiments should be made comparing the thermal 
emission from radium wholly surrounded with thick lead 
with that found with the surroundings hitherto used. 

