The arc spectrum has been examined by Kayser, Eberhard,[418] and Eder and Valenta;[419] Exner and Haschek give the following as the most intense lines:
| 3216·83 | 3774·52 | 4177·74 |
| 3242·42 | 3788·88 | 4302·45 |
| 3328·02 | 3950·52 | 4309·79 |
| 3600·92 | 3982·79 | 4348·93 |
| 3611·20 | 4077·54 | 4375·12 |
| 3621·10 | 4102·57 | 4883·89 |
| 3633·28 | 4128·50 | 6191·91 |
| 3664·78 | 4143·03 | 6435·27 |
| 3710·47 | ||
[418] Zeitsch. wiss. Photochem. 1909, 7, 245.
[419] Sitzungsber. kaiserl. Akad. Wiss. Wien, 1910, 119, IIa, 1.
Pure yttrium compounds should be colourless, show no absorption in the visible region, and yield a perfectly white oxide.
Scandium, Sc = 44·1
The scandia obtained by Nilson in 1879 was isolated from the minerals gadolinite and euxenite; it consisted very largely of ytterbia, as shown by spectrum examination[420] and by atomic weight determinations, which gave the value 90. In the same year[421] Cleve prepared the oxide in a much purer state, using as his source the minerals gadolinite and keilhauite; he described several salts, carried out atomic weight determinations by the analytical and synthetic sulphate methods, and showed that scandium corresponds with the Eka-boron of which the existence was predicted by Mendelejeff in 1871.[422] Starting from a large quantity of euxenite, Nilson[423] in the following year prepared several grams of approximately pure scandia, which contained only traces of ytterbium.
[420] Thalén, Compt. rend. 1879, 88, 642; 1880, 91, 45.
[421] Compt. rend. 1879, 88, 419.
[422] See also Mendelejeff, Ber. 1881, 14, 2821.