THE RARE EARTHS.—MAGEE. Ixv 
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 go on until these most subtle elements. 
yield to the scientists truths even more deeply and cunningly concealea 
than those which are being discovered in the realms of electricity 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. Asa result of this discovery, an immediate attack was made on 
the other rare earths. Mosander himself in the following year announced 
Erbia and, later, Terbia, 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 1860 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, 
