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XOXTE. 
ON THE SEPARATION AND QUANTITATIVE SPECTRA OF 
CERIUM, LANTHANUM, AND YTTRIUM. 
By JAMES H. POLLOK, D.Sc., anp A. G. G. LEONARD, A.R.C.S.L., 
Royal College of Science, Dublin. 
[Puates XXI.-XXIII.] 
[Read, December 17; Received for Publication, DecremMBEr 29, 1907; 
Published, Frpruary 17, 1908.] 
PREPARATION OF THE PuRE Harrus. 
Tren pounds weight of cerite was decomposed by fusion with its 
own weight of caustic soda in a large salamander crucible. The 
fusion was done in eight successive charges, and each charge took 
about one hour in an ordinary wind-furnace used for gold assays ; 
after fusion the charge was perfectly liquid and poured well. 
This method of decomposing silicates of the rare earths on a large 
scale is preferable to fusion with the mixed carbonates of the 
alkalis, as much less flux is necessary, and consequently less 
chemicals in the subsequent decomposition, and the mixture 
does not froth so much in the crucible. The fusion was then 
ground, treated with excess of hydrochloric acid, the solutions 
decanted off, and the residue boiled with more hydrochloric acid 
by passing steam into it for some hours; the insoluble silica was 
then filtered off. On decomposing a small portion of the silica 
with hydrofluoric acid in the usual way, it was found to leave a 
residue of about 4 per cent. of itsown weight. On dissolving this 
residue in strong hydrochloric acid, and photographing and 
examining its spectrum, it was found to consist principally of 
titanium and some of the cerite minerals that had not been 
completely separated, but nothing else. The hydrochloric acid 
solutions were mixed, diluted, and treated with sulphuretted 
hydrogen for the separation of a small quantity of lead and copper ; 
they were then boiled and treated with excess of oxalic acid ; and 
SCIENT. PROC. R.D.S,, VOL. XI., NO. XXIII. 2M 
