THE RARE EARTHS. MAGEE. 



truths were rapidly unfolded and a new interest was given to this portion 

 of the chemical field, an interest which has constantly increased, and under 

 the influence of which research will goon until these most subtle elements 

 yield to the scientists truths even more deeply and cunningly concealed 

 than those which are being discovered in the realms of electiicity and 

 bacteriology. I think it is no exaggeration to say that nothing would 

 give more pleasure to the chemical world than to find a solution to the. 

 mystery which surrounds these rare earths, now rare no longer, if by the 

 word, we mean scarce, but truly rare if we consider it as meaning costly 

 or worthy as regards the chemical truth concealed among them. This 

 chemist was Mosander a name probably unknown outside the chemical 

 world, and not to all chemists. To the advanced inorganic chemist, how- 

 ever, he is the pioneer in the field, since he was the first to show the 

 immense possibilities which lay concealed in the little then known of 

 these peculiar earths. 



Beginning an examination of Ceria he soon announced that it was 

 not a simple oxide but a compound of at least two. This was in 1838. 

 In 1843 he announced that one of these two could be still further de- 

 composed and so from the earth Ceria, long considered a simple earth, 

 there resulted a pale yellow oxide, ceria proper, a brownish white oxide, 

 lanthanum, and a dark brown oxide, didymia, the first yielding yellow, 

 white, and red salts, the second white or colorless, and the third pink 

 salts. As a result of this discovery, an immediate attack was made on 

 the other rare earths. Mosander himself in the following year announced 

 Erbia and, later, Tcrbia, as earths separable from Yttria ; these yield, 

 Yitria colorless salts, Erbia yellow, and Terbia rose colored, a coincidence 

 with the compounds from the Ceria earths. In I860 Berlin, as a result 

 of long research, announced that Mosander had been mistaken as regards 

 Yttria, but later work has shown that the Swedish chemist had not 

 spoken heedlessly, for Bahr and Bunsen, by a very brilliant piece of 

 work, proved the presence of Erbia in so-called Yttria, and in 1873 Cleve 

 and Hoglund confirmed this. About this time Delafontaine again deter- 

 mined the existence of Terbia. Later, Delafontaine claimed the dis- 

 covery of an earth, which he called Phillipia, in the Yttria, but this is 

 not as yet acknowledged by chemists. Then came a classical research by 

 Marignac, a Swiss chemist, in which, after separating out several appar- 

 ently distinct earths, he finally isolated Ytterbium, which is undoultedly 

 a distinct element, though some chemists, keeping in view the many sur- 

 prises in this field, still withheld acknowledgment. In 1879, Nilson, 



