THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



OCTOBER 1843. 



XXX. On the new metals, Lanthanium and Didymium, which 

 are associated with Cerium ; and on Erbium and Terbium, 

 new metals associated with Yttria. By Professor C. G. 



MOSANDER*. 



A LTHOUGH in consequence of the imperfect nature of 

 ^*- the results which were obtained from my researches on 

 cerium and lanthanium I had no intention of making anv 

 communication on the subject on the present occasion, yet 

 after hearing the interesting statement of Professor Scheerer, 

 it appeared to me that it might be useful to make known more 

 generally some particulars which arose during my labours, 

 and principally because this advantage may result, that other 

 chemists, after becoming acquainted with what I am about to 

 state, may possibly be spared the loss of valuable time which 

 might otherwise have been fruitlessly expended. 



When sixteen years since I made some experiments upon 

 cerium, several circumstances occurred which led me to the 

 supposition that oxide of cerium was accompanied by some 

 other oxide, which, however, I did not succeed in separating, 

 and want of materials prevented me from then prosecuting 

 the inquiry. A few years since, having procured a quantity 

 of cerite and cerine, I prepared from thence the double salt of 

 sulphate of the oxide of cerium with sulphate of potash, which 

 salt was washed with a solution of sulphate of potash, until 

 the passing fluid gave no trace of precipitate with caustic am- 

 monia or carbonate of soda. I believed that in this manner 

 I could obtain a pure salt free from all foreign substances. 



* Communicated to the Meeting of the Scandinavian Association at 

 Stockholm, July 1842. Translated from the Swedish by Major North 

 Ludlow Beamish, F.R.S., President of the Cork Scientific and Literary 

 Society ; and read before the Section of Chemistry and Mineralogy of the 

 British Association, meeting at Cork, August 18, 1843. 



Phil. Mag. S.3. Vol. 23. No. 152. Oct. 184-3. R 



