THE DETECTION AND WIDE DISTRIBUTION OF YTTRIUM. 
905 
41. Some of these claimants will certainly not stand the test of further scrutiny. 
Thus samarium and yttrium /3 are in all probability identical; and I should 
scarcely have included philippiurn, as Hoscoe " has conclusively proved that this is a 
mixture of terbium and yttrium, and my own results (61) confirm those of Roscoe. 
Moreover, others of these so-called elements will probably turn out to be mixtures of 
known elements. But in the confessedly very imperfect state of our knowledge of the 
chemistry of these metals it is not safe for me in this research to assume that any one 
of them will surely not survive. The complete list as it stands will therefore be taken 
to contain all hitherto claimed as new, although it is almost certain to include too many. 
The sought-for body has no absorption spectrum. 
42. In the second column “ Yes ” or “ No ” indicates whether the solutions give an 
absorption spectrum when examined by transmitted light. Now could I definitely 
settle whether solutions of the citron-band body gave an absorption spectrum or not, 
I could at once eliminate a whole class of elements. 
This was not difficult to determine. I have already said (22, 24) that spectroscopic 
examination entirely failed to detect didymium in many solutions of the earth which 
gave the citron band strongly. This was not always the case. In early days of this 
research I frequently obtained absorption bands innumerable when the citron-band 
body was known to be present; but as I became better acquainted with the chemical 
reactions of the new earth I gradually succeeded in eliminating one after the other * 
those metals yielding absorption spectra. The earth from zircons (18, 21) gave the 
most satisfactory results in this respect. This, after removing the little didymium 
present, gave but a trace of an absorption spectrum, which from its general appearance 
was probably due to erbia. The earth obtained from cerite (25), which gave the citron 
spectrum with great brilliancy, on the other hand yielded no absorption spectrum ; 
and generally I may say that, whenever I started with a sufficient quantity of an earth 
giving both citron-band spectrum and absorption spectrum, I could, by appropriate 
chemical means, always separate it into three portions,— one which gave the citron- 
band spectrum with great brilliancy, and showed in concentrated solution a very faint 
absorption spectrum, and frequently none at all; another which gave very little citron- 
band spectrum, but a good absorption spectrum ; and a third intermediate portion— 
about four-fifths of the whole—which gave both citron band and absorption spectrum. 
This portion, by repetition of the treatment, could again be split up in the same way, 
and the operation repeated as often as the stock of material held out. 
43. Having definitely settled the question that the metal giving the citron-band 
spectrum was not one of those giving an absorption spectrum, the possible elements 
become materially narrowed to the following list :—Cerium, lanthanum, mosandrum, 
scandium, terbium, thorium, ytterbium, yttrium, yttrium a, and zirconium. 
* ‘ Jour. Chem. Soc.,’ vol. 41, p. 277. 
