204 



Mr. J. Norman Lockyer. 



laboratory possibilities, for the highest temperature I hare employed 

 only carries us to the heat level of 7 Cygni, in which star the cleveite 

 gases, if visible, give only very faint traces. We are thus brought 

 rinally face to face with the fact that iron is a compound, into the 

 ultimate formation of which hydrogen, or the cleveite gases, or both, 

 enter, and thus the appearance of D 3 in the chromosphere associated 

 with the enhanced lines of iron is finally explained. The stars 

 included in the present discussion do not enable us to say finally 

 whether hydrogen, excluding the new form, or the cleveite gases, 

 are primordial among those at present known to us, but there is 

 already evidence furnished by /3 Lyrse and Tauri, that that position 

 will probably have to be accorded to the cleveite gases, dealing with 

 those with which we at present are familiar. 



But the discovery of Professor Pickering of the new form of hydro- 

 gen, to which allusion has been made, must have a most important 

 bearing upon this conclusion, especially if, as suggested by Kayser 

 and myself, the principal series of hydrogen is still beyond our ken, 

 because this would indicate that even in the hottest stars so far con- 

 sidered, the temperature is not high enough to allow its molecule to 

 exist uncombined. 



My son, Dr. W. J. S. Lockyer, is now engaged upon this and allied 

 problems in connection with other series he has discovered in 

 Bellatrix, and the spectra of other stars at the apex of the tempera- 

 ture curve, including the detailed facts with regard to the appearance 

 of the various series of the cleveite gases. 



The ultimate Molecules involved. 



It follows from the preceding statements that, so far as the power 

 of resisting the effect of temperature is concerned, the ultimate 

 molecules at present within our ken of the chemical elements dis- 

 cussed in this memoir may be arranged provisionally in the following 

 order : — 



Uncertain, probably f Gas X 

 correct order. \ He 

 H 

 Ca 



Fe 



The ultimate molecules of Ca. Kg, and Fe thus indicated may be 

 considered as representing the vibration of a proto-calcium, proto- 

 magnesium, and proto-ferrum in stars of medium temperature. 



The above is put forward with all reserve, for it must be remem- 

 bered that we are only dealing with stars in our own part of space, 

 ai;d that only a small part of the spectrum has been studied. 



