—The spark spectra are of more use in distinguishing the two elements than the arc spectra. The spark spectrum of the old ytterbium was mapped by Exner and Haschek,[394] and of the two compounds by both discoverers (loc. cit.). See also Eder and Valenta.[395]
[394] Sitzungsber. kaiserl. Akad. Wiss. Wien, 1899, 108, IIa, 1123.
[395] Ibid. 1910, 119, IIa, 3.
The arc spectra have been mapped by Eder and Valenta (loc. cit.) and by Exner and Haschek; the latter authors give as the most intense lines the following:
| Yb | Lu | ||
| ╵ | |||
| 3031·26 | 2615·50 | 3397·21 | 4124·87 |
| 3107·99 | 2911·53 | 3472·65 | 4184·40 |
| 3289·50 | 3077·75 | 3507·57 | 4518·74 |
| 3464·47 | 3198·27 | 3508·55 | 5476·88 |
| 3988·16 | 3254·45 | 3554·58 | 5983·92 |
| 5556·67 | 3281·89 | 3568·00 | 5984·32 |
| 3312·30 | 3624·10 | 6222·10 | |
| 3359·74 | 3636·41 | 6463·40 | |
| 3376·69 | 3876·80 | ||
Celtium
The separation of Marignac’s ytterbium into the two elements described above was accomplished by Urbain with the yttria earths extracted from xenotime. In carrying out the same process with the ytterbia earths from gadolinite, that author[396] obtained from the mother-liquor an earth for which the coefficient of magnetisation was found to be 4·1 × 10⁻⁶; lutecia has a coefficient three to four times as great. A spectroscopic examination revealed the presence of lines which did not correspond with those of any known body, and Urbain considered that a new element, for which he proposed the name Celtium, with the symbol Ct, must be present. Lutecia from xenotime shows no trace of the new element.
[396] Compt. rend. 1911, 152, 141.
Spectroscopic evidence for the existence of a third ytterbium element had previously been brought forward by Auer von Welsbach[397] and also by Exner and Haschek.[398]
[397] Monats. 1908, 29, 204.