ADDRESS. 29 



from other groups. Special processes were employed to isolate tJic earth, 

 and using these lines as a test, and appealing at every step to the spectro- 

 graph, it was pleasant to see how each week the group stood out stronger 

 and stronger, while the other lines of yttrium, samarium, ytterbium, tl-c, 

 became fainter, and at last, practically vanishing, left the sought-for group 

 strong and solitary. Finally, within the last few weeks, hopefulness has 

 emerged into certainty, and I have absolute evidence that another member 

 of the rare earth groups has been added to the list. Simultaneously with 

 the chemical and spectrographic attack, atomic weight determinations 

 were constantly performed. 



As the group of lines which betrayed its existence stand alone, almost 

 at the extreme end of the ultra-violet spectrum, I propose to name the 

 newest of the elements Monium, from the Greek /(dro?, alone. Although 

 caught by the searching rays of the spectrum, Monium offers a direct 

 contrast to the recently discovered gaseous elements, by having a strongly 

 marked individuality ; but although so young and wilful, it is willing to 

 enter into any number of chemical alliances. 



Until my material is in a greater state of purity I hesitate to commit 

 myself to figures ; but I may say that the wave-lengths of the principal 

 lines are 3120 and 3117. Other fainter lines are at 3219, 3064, and 

 3060. The atomic weight of the element, based on the assumption of 

 RoOj, is not far from 118— greater than that accepted for yttrium and 

 less than that for lanthanum. 



I ought almost to apologise for adding to the already too long list of ele- 

 ments of the rare earth class — the asteroids of the terrestrial family. But 

 as the host of celestial asteroids, unimportant individually, become of high 

 interest when once the idea is grasped that they may be incompletely 

 coagulated remains of the original nebula, so do these elusive and insig- 

 nificant rare elements rise to supreme importance when we regard them 

 in the light of component parts of a dominant element, frozen in embryo, 

 and an-ested in the act of coalescing from the original protyle into one 

 of the ordinary and law-abiding family for whom Newlands and Mende- 

 leeff have prepared pigeon-holes. The new element has anotlier claim to 

 notice. Not only is it new in itself, but to discover it a new tool had to 

 be forged for spectroscopic research. 



Further details I will reserve for that tribunal before whom every 

 aspirant for a place in the elemental hierarchy has to substantiate his 

 claim. 



These, then, are some of the subjects, weighty and far-reaching, on 

 which my own attention has been chiefly concentrated. Upon one other 

 interest I have not yet touched — to me the weightiest and the farthest 

 reaching of all. 



No incident in my scientific career is more widely known than the 

 part I took many years ago in certain psychic researches. Thirty years 



