
INORGANIC EVOLUTION 13 
and that the same element might, as many of them 
did, give totally different spectra when subjected to 
the following markedly increasing degrees of heat :-— 
(a) The temperature of a flame. 
(4) The temperature of the electric arc. 
(c) The temperature due to an electric spark of 
very high potential. 
When examined in the laboratory at these 
different temperatures the spectra of iron, of 
magnesium, of calcium and other elements are 
found to vary in ways which seem incapable of 
explanation except on the assumption that the 
changes when passing from (a) to (4) or (c) are due 
to dissociation of the elements under the influence of 
the high temperatures to which they are subjected— 
that is, that the simplification of the spectra thus 
produced is due to the breaking up of their atoms 
into simpler groupings of corpuscles or electrons. 
The significance of these variations has been vastly 
increased owing to the fact that precisely the same 
kind of changes which are seen in the laboratory 
are also recognisable in the spectra of the elements 
as they exist in the chromosphere of the sun, and 
in the light emanating from many stars. Concern- 
ing the latter bodies Kennedy Duncan says (doc. cz¢. 
p. 204): “The spectra of the stars afford in many 
cases the same simplified spectra observed in the 
sun of iron, magnesium, and calcium. In addition, 
simplified spectra of other metals are discovered, 
such as titanium, copper, manganese, nickel, 
chromium, vanadium, and strontium. To these 
supposedly broken-down metals the prefix proéo is 
