1883.J 



On Radiant Matter Spectroscopy. 



267 



Some of these claimants it is certain will not stand the test of 

 further scrutiny. Thus samarium and yttrium /3 are in all probability 

 identical; and I have not included philippium, as Roscoe has conclu- 

 sively proved that this is a mixture of terbium and yttrium, and my 

 own results confirm those of Roscoe. Moreover, some of these so- 

 called elements will probably turn out to be mixtures of other known 

 elements. But in the confessedly very imperfect state of our know- 

 ledge 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. 



In the second column " Yes " or " JSTo " indicates whether the solu- 

 tions give an absorption spectrum when examined by transmitted 

 light. After numerous experiments I. satisfied myself that the metal 

 giving the citron band spectrum was not one of those giving an 

 absorption spectrum. The possible elements, therefore, became 

 narrowed to the following list : — ^.Cerium, lanthanum, mosandrum, 

 scandium, terbium, .thorium, ytterbium, yttrium, yttrium and 

 zirconium. 



Of these the potassic sulphate reaction excludes cerium, lanthanum, 

 scandium, thorium, yttrium and .zirconium, so there are left only the 

 following : — 



Mosandrum, 

 Terbium, 

 Ytterbium, 

 Yttrium. 



Certain chemical reactions for a long time made me dismiss yttrium 

 from the list of likely bodies. In my analysis of zircons, towards the 

 latter part of the process, I used the following process to separate the 

 iron : — The solution mixed with tartaric acid and excess of ammonia 

 was allowed to stand for some time. A small quantity of a precipitate 

 gradually formed, which was filtered off, and it was this filtrate, after 

 separating the iron with ammonic sulphide, that yielded the greatest 

 quantity of substance giving the citron band. Now one of the methods 

 of separating yttria from alumina, beryllia, thoria, and zirconia is to 

 precipitate it as tartrate in the presence of excess of ammonia, the 

 other earths remaining in solution. Fresenius says : — " The precipita- 

 tion ensues only after some time, but it is complete." 



The precipitate thus obtained with tartaric acid and ammonia should 

 therefore contain all the yttria : it gave no citron band whatever in the 

 radiant matter tube; whilst the residue, which should be free from 



simplicity in calculating the values from the composition of their salts, by which 

 these metals are chiefly discriminated, taken the type of oxide to be M^O. 



