IN CONNEXION WITH THE SPECTRUM OE THE SUN. 
493 
to violet light, may (as I have found in a repetition of Dr. Andrews’s experiments on the 
dichroism of iodine, in which I observed the spectrum) in part be driven into the violet 
end of the spectrum, for iodine in a solution in water or alcohol at once gives up its 
ordinary absorption properties and stops violet light*. 
A preliminary comparison of the ordinary absorption-spectrum of a stratum of 6 feet 
of chlorine renders it not improbable that chlorine at a low temperature is the cause 
of some of the Fraunhofer lines in the violet, although, as said before, I have not yet 
obtained certain evidence as to the reversal of the bright lines of chlorine seen in the 
jar-spark. 
There is also an apparent coincidence between some of the faint Fraunhofer lines 
and some of the lines of the low temperature absorption-spectrum of iodine. 
Should subsequent researches strengthen the probability of this working hypothesis, 
it seems possible that iron meteorites will be associated with the metallic stars and stony 
meteorites with metalloidal and compound stars. Of the iron group of metals in the 
sun, iron and nickel are those which exist in greatest quantity, as I have determined 
from the number of lines reversed. Other striking facts, such as the presence of 
hydrogen in meteorites, might also be referred to. 
An interesting physical speculation connected with this working hypothesis is the 
effect on the period of duration of a star’s heat which would be brought about by 
assuming that the original atoms of which a star is composed are possessed with the 
increased potential energy of combination which this hypothesis endows them with. 
From the earliest phase of a star’s life the dissipation of energy would, as it were, bring 
into play a new supply of heat, and so prolong the star’s light. 
May it not also be that if chemists take up this question which has arisen from the 
spectroscopic evidence of what I have before termed the plasticity of the molecules of 
the metalloids taken as a whole, much of the power of variation which is at present 
accorded to metals may be traced home to the metalloids 1 I need only refer to the 
fact that, so far as I can learn, all so-called changes of atomicity take place when metal- 
loids are involved, and not when metals alone are in question. 
As instances of these, I may refer to the triatomic combinations formed with chlorine, 
oxygen, sulphur, &c. in the case of tetrad or hexad metals. 
May we not from these ideas be justified in defining a metal, provisionally, as a 
substance, the absorption-spectrum of which is generally the same as the radiation- 
spectrum, while the metalloids are substances the absorption-spectrum of which, gene- 
rally, is not the same 1 In other words, in passing from a cold to a comparatively hot 
state, the plasticity of these latter comes into play, and we get a new molecular arrange- 
ment. Hence are we not justified in asking whether the change from oxygen to ozone 
is but a type of what takes place in all metalloids \ 
My best thanks are due to Mr. R. J. Friswell for the valuable aid he has afforded 
me in these investigations. 
* I have since obtained the same result by observing the absorption of I vapour in a wbite-hot tube. 
MDCCCLXXIV. 3 u 
