538 Prof. R. Bunsen's Spectral-Analytical Researches. 



with the liquid gave a spark- spectrum, in which 10 lanthanum 

 lines, and the cerium lines at 67*8, 70*9, 79*4 (no. 13 e), 

 appeared clearly; the spark-spectrum in hydrogen showed no 

 magnesium lines. The spectrum obtained by placing a platinum 

 wire, on which a little of the liquid had been allowed to eva- 

 porate in the non-luminous flame, exhibited faint calcium-lines 

 (no. 7 a) ; in the spark-spectrum the calcium line at 49 (7 e) 

 appeared very faintly. 



2. Gadolinite from Ytterbij. — The liquid obtained after sepa- 

 rating silica by evaporation with hydrochloric acid, gave the 

 didymium absorption-spectrum, the bands which appear at 55 

 (15 a) being especially marked : the absorption-bands of erbium 

 appeared faintly, especially 35 (11 a) ; 65 and 68 were very faint 

 but yet visible. The calcium-spectrum appeared slightly, and 

 the sodium-spectrum very faintly when the liquid was placed on 

 a platinum wire in the flame. The yttrium-lines appeared very 

 plainly in the spark-spectrum, the characteristic group of lines 

 between 40 and 50 (12 e) being especially visible. The cerium- 

 line 70-9 (13 e) appeared in'the same spectrum; but the lantha- 

 num lines did not appear. As the lanthanum-spectrum is 

 characterized by many and well-marked lines, it is evident that 

 the mineral under examination either contained no lanthanum 

 or but the smallest trace of that element. Yttrium, erbium, 

 didymium, cerium, calcium, and sodium were therefore found in 

 this mineral. 



3. Very pure orangite from Brewig, treated as above described, 

 showed faintly the characteristic bands of didymium at 54 (15a). 

 The cerium-lines 70*9 and 67'5 (13 a), and the lanthanum-line 

 87 (14 a), were plainly visible in the spark-spectrum. The cal- 

 cium-spectrum appeared when the liquid was placed in the 

 flame. 



4. Wasite yielded, a solution in which the absorption-bands 

 of didymium, 55 and 75 (15 a), but no erbium bands appeared. 

 The flame-spectrum showed calcium-lines. The spark-spectrum 

 showed plainly only the cerium-line 70*9 (13 e). In conse- 

 quence of an excessive quantity of alumina and iron in the liquid, 

 the lines of the other earths only appeared after treating the 

 precipitate thrown down by ammonia with oxalic acid, igniting 

 the oxalates thus formed, and dissolving the residue in hydro- 

 chloric acid. A very intense yttrium-spectrum,, along with the 

 characteristic cerium-lines 70*9 and 67*7 (13 e), was then ren- 

 dered visible. No trace of lanthanum was discoverable. 



5. Euxenite.—A. small quantity was fused with sodium car- 

 bonate, the mass was evaporated with hydrochloric acid and 

 taken up with the same acid diluted with water. The solution 

 was precipitated by ammonia, and the precipitate digested with 



