186 INORGANIC EVOLUTION. [CHAP, 



express their atomic weight might be well spared. But it is not a 

 question 'of apparent impurities only. 



It is possible that some of the gases of lower atomic weight which 1 

 exist in the Hottest stars may be represented by A in opposition to 

 heavy metals represented by Z, the existence of which is -known in the 

 cooler stars only. 



The giving off of gases from metals when high tension electricity 

 is employed is well known. This has been explained by assuming 

 them to be " furnace gases," that is gases "occluded" by the metals 

 during their reduction. But this does not seem to be a sufficient 

 explanation, for the same gases are given off by meteorites. We now 

 see why something like this may happen if there is any foundation for 

 the modern conception of the structure of the "atom"; and do not 

 these facts explain the chemistry of the hottest stars 1 



It is too early yet to attempt to discuss the effects of the electric- 

 charge in this connection, but it must be pointed out that so soon as 

 the ions, however associated their units may be, which are supposed 

 always to have an electric charge upon them, are subjected to the 

 action of a voltaic or induced current, the spectral phenomena ob- 

 served when they are heated are liable to great changes in seme 

 cases, and especially when high atomic weights are in question; 

 Doubtless we have here a field of research which will ultimately 

 supply us with the most precious knowledge. I have already shown 

 that with the gases, such as hydrogen and oxygen, heat alone gives 

 rise to no spectral phenomena, while in the case of such metals as 

 sodium, heat is so effective in its dissociating power that the subse- 

 quent application of electricity produces no further change. 



We have, in fact, to consider that the effects produced on different 

 substances under the same conditions may be different, and that the 

 stars carry us further than our laboratories; that is, there are staged 

 of spectral change within and beyond our experimental powers reveal- 

 ing a shedding of ions or some rearrangement of material at different 

 temperatures. Of course it is possible that the rearrangement of 

 material may take place in the central molecule itself ; the point to be 

 remembered is, that whatever may happen, whether in the central 

 molecule or the ion, a higher temperature will be associated with a 

 simplification of the total mechanism. 



Dr. Preston's Researches. 



Quite recently the study -of magnetic perturbations of spectral 

 lines has brought a fresh array of evidence on this question. 



It has now been proved that spectral phenomena are different 



