Poitox anp Lronarp—On the Spectra of Cerium, &c. 267 
YTTRIUM. 
Plates XXII. and XXIII., spectra 1 and 2, show the spectra 
of solutions of yttrium chloride containing respectively 10 per 
cent. and 1 per cent. of the element. Yttrium gives a strong 
characteristic spectrum, of great persistency ; and the lines marked 
x and y stand out well in those dilutions. 
QUANTITATIVE SPECTRUM oF YTTRIUM CHLORIDE. 
oe Wave- ey enna: Wave- ey 
ons ae Jonge Persistency. Fasc Hane D. Persistency. 
244°7 5648°7 5 307°9 4315-4 Au No. 11 
247°5 5582-1 5 308-5 4309°8 20 » 
248°6 5544°8 5 317-9 4177-7 50 y 
250°3 5497-6 5 320°6 4143-0 i) 
251-4 5466-7 6 321°6 4128°5 79 
253°7 5403°0 4 323°8 4102°5 6 o 
261°2 5205°9 6 > 326°8 4065°2 Au No. 12 
266°1 5087°6 5 x 333°6 3982°7 20 » 
274°6 4900°3 6 x 341-2 3898°0 Au No. 13 
275°3 4883-9 6 x 347-3 3833°0 20 
276°8 4855°1 6 351°6 3788-8 30 @ 
279°9 4792°8 Au No. 9 353°1 377475 100 x 
286-1 4675-0 4 360-0 3710°4 100 x 
287-9 4643°8 4 | 364°7 3664°8 20 
294°5 4527-4 30 | 370°7 3611°2 30 x 
296°9 4488-4 Au No. 10 371°8 3600°9 50 x 
301-0 4422°8 10 373°6 3586°7 Au No. 14 
302°5 4402°5 Yb ? 378°1 3549-2 20 
304°0 4375°1 100” y 384°6 3496°2 10 
