“ST 
2 a 
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‘ 
318 RADIO-ACTIVE PROCESSES [CH. 
weight. Ata later date Mr Soddy and the writer showed that the 
radium and thorium emanations behaved like chemically inert 
gases, since they were unaffected by the most drastic physical 
and chemical treatment. 
On the other hand, P. Curie, who, in conjunction with Debierne, 
had made a series of researches on the radium emanation, expressed 
dissent from this view. P. Curie! did not consider that there was 
sufficient evidence that the emanation was material in nature, and 
pointed out that no spectroscopic evidence of its presence had yet 
been obtained, and also that the emanation disappeared when 
contained in a sealed vessel. It was pointed out by the writer? 
that the failure to detect spectroscopic lines was probably a conse- 
quence of the minute quantity of the emanation present, under 
ordinary conditions, although the electrical and phosphorescent 
actions produced by this small quantity are very marked. This 
contention is borne out by calculations of the probable amount of 
the emanation released from 1 gram of radium given in section 162. 
P. Curie took the view that the emanation was not material, 
but consisted of centres of condensation of energy attached to the 
gas molecules and moving with them. 
M. and Mme Curie have throughout taken a very general view 
of the phenomena of radio-activity, and have not put forward any 
definite theory. In Jan. 1902, they gave an account of the general 
working theory* which had guided them in their researches. 
Radio-activity is an atomic property, and the recognition of this 
fact had created their methods of research. Each atom acts as a> 
constant source of emission of energy. This energy may either 
be derived from the potential energy of the atom itself, or each 
atom may act as a mechanism which instantly regains the energy 
which is lost. They suggested that this energy may be borrowed 
from the surrounding air in some way not contemplated by the 
principle of Carnot. 
In the course of a detailed study of the radio-activity of thorium, 
Mr Soddy and the writer* found that it was necessary to suppose 
that thorium was continuously producing from itself new kinds of 
1 C. R. 136, p. 223, 1903. 2 Phil. Mag. April, 1903. 
3 C. R. 134, p. 85, 1902. 
+ Trans. Chem. Soc. 81, pp. 321, 837, 1902. Phil. Mag. Sept. and Nov. 1902. 
