Referee report by T. R. Robinson on 'On the Spectra of Ignited Gases and Vapours, with Especial Regard to the Different Spectra of the Same Elementary Gaseous Substance' by J. Plücker and J. Hittorf

                                April 4. 1864
My dear Stokes 
I have carefully read Dr Pluckers paper 
and think it a very important contribution to our know=
ledge of spectrology, though it is by no means free 
from arbitrary assumptions; or, as I think, from loose 
or even erroneous statements. In some facts I am glad 
to find he confirms, with far superior means of observa=
tion, my previous conclusions 
The most notable points which he has established are 
1 An excess of one gas, often but not always, prevents 
the spectral lines of another from appearing. Exam 
ples of this are afforded by Nitrogen, Carbon, Sulphur 
and Hydrogen. In many instances however the jar-
discharge brings out the lines, though the spark 
does not 
2 Some gases, as Oxygen, require a much higher 
electric power than others to bring out their lines 
(this I have found to be the case with metals also)
3 The peculiar Pillared appearance of the bands at 
the most refrangible end in certain spectra is 
shewn to arise from a shading with fine dark lines 
4 In some cases a compound shews lines of its own in ad =
di[ti]on to those of its elements 
5 Certain elements give different spectra at 
different temperatures (this had been shewn 
by Gladstone and others. T.R.R.) 
6 The absorption-spectrum of Iodine is not the inverse 
of its Luminous one. (this however was already 
proved by Dr A. Miller. T.R.R.)
7 The principal part is devoted to shew the existence 
for many bodies of two or more Electric spectra 
(Carbon has four). Those which he calls of the First 
order are obtained by the discharge of Ruhmkorf 
large Induction Machine through the gas or vapour