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XIX. On the Photographic Arc Spectrum of Iron Meteorites. 
By J. Norman Lockyer, C.B., F.R.S. 
Received December 22, 1893,—Read February 15, 1894. 
In a communication to the Royal Society in 1887,* I gave an account of certain 
experiments which I had made in connection with the spectra of various meteorites at 
various temperatures. The spectra were observed at the temperature of the oxy- 
hydrogen flame and the electric spark without jar, and when glowed in vacuum tubes. 
Some larger specimens of the iron meteorites, Nejed and Obernkirchen, cut so that 
they were of a size and shape suitable for forming the poles of an arc lamp, having 
afterwards been kindly placed at my disposal by the Trustees of the Britisli Museum, 
it became possible to study the arc spectra of these meteorites under very favour¬ 
able conditions, all impurities introduced by the use of the carbon poles being thus 
avoided. 
The region of the spectrum photographed extends from K to D, in the case of each 
meteorite, and in addition to the solar spectrum, that of electrolytic iron, prepared 
by Professor Roberts-Austen, referred to in a previous communication, has been used 
as a comparison spectrum in one case. 
The photographs obtained are as follows ;— 
(1) Nejed Meteorite. 
(2) Obernkirchen Meteorite. 
(3) „ „ . 
(4) Composite Meteorites on Nejed poles. 
(5) ,, ,, „ Silver poles (region 393 421) 
Comparison spectrum. 
Sun 
Iron 
Sun 
Composite meteorites 
on carbon poles 
The instruments and arrangements used for photographing the spectrum were 
exactly the same as those which I have described in the case of the iron spectrum in 
the communication referred to above. The spectrum was photographed in three 
sections, X\ 39-42, 42-47, and 47-59. The photographic plates employed were also 
* ‘Roy. Proc. Soc.,’ vol. 4.3, p. 117. 
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