Nature of the so-called Elements. 115 
simple than that which gives us / alone, the other more com- 
plex than that which gives us F alone. The evidence on this 
point is of such extreme importance to solar physics and 
throws so much light on star structure generally, that I shall 
reserve it for a special communication. | 
In the meantime I content myself by giving a diagram (Fig. 7) 
in which I have arranged the various groupings of hydrogen as 
they appear to exist, from the regions of highest to those of 
lowest temperature in our central luminary. 
Summation of the above Series of Facts. 
I submit that the facts above recorded are easily grouped 
together, and a perfect continuity of phenomena established on 
the hypothesis of successive dissociations analogous to those 
observed in the cases of undoubted compounds. 
The other Branches of the Inquiry. 
When we pass to the other possible evolutionary processes 
to which I have before referred, an i hope to discuss 
on a future occasion, the inquiry becomes much more compli- 
cated by the extreme difficulty of obtaining pure specimens to 
work with, although I should remark that in the working 
hypothesis now under discussion’,the cause of the constant 
occurrence of the same substance as an impurity in the same 
pieces of palladium; Dr. Hugo Miiller, who has furnished me 
the effects of impurities. I am therefore aware of the great 
necessity for caution in the spectroscopic examination of yarious 
