360 SIR WILLIAM CEOOKES ON SCANDIUM. 



raw scaridia prepared by the above methods still contains small quantities of yttria 

 and ytterbia, particularly if method (&) is used. Prof. MEYER says that his scandia, 

 when freed from cerium and yttrium earths, has the atomic weight 45 to 46, and still 

 contains about 1 per cent, of thorium.* 



On reading Prof. MEYER'S paper I examined the felspar and mica which were 

 associated with the parcels of wiikite procured by me from Finland. The felspar 

 contains a small percentage of rare earths, but 110 trace of scandia could I detect on 

 examining their photographed spectra, the dominant line, wave-length 3613'984, 

 being entirely absent. 



The mica was found to contain about 1 per cent, of rare earths, and in the 

 photographed spectrum the dominant lines of scandium are plainly visible. From a 

 comparison of the spectra with those taken with the rare earths from wiikite I should 

 estimate the scandia at about half that in the earths of the best black wiikite. 



A specimen of wolframite from Zinnwald was found to contain less than 1 per cent, 

 of rare earths, and in the photographed spectrum of these earths, the dominant lines 

 of scandium were strong, accompanied by only the faintest trace of yttrium or 

 ytterbium lines. 



Through the kindness of a friend, Dr. WAHL, of the Miueralogical Institute, 

 University, Helsingfbrs, I also obtained the following authentic specimens of minerals 

 from the locality whence my wiikite was mined : 



No. 1. Felspar from the pegmatite vein carrying monazite and the scandium- 



wiikite. Lokasaari. 

 No. 2. Monazite from Lokasaari. 

 No. 3. Black wiikite from Lokasaari, Impilaks. 

 No. 4. Brown wiikite from Lokasaari. 

 No. 5. Wiikite from Lokasaari, another specimen. 

 No. 6. Mica from Hunttila, Impilaks. (Probably from the wiikite quarry.) 



Of Dr. WAHL'S minerals, No. 1, felspar, contained I'll per cent, of rare earths. 

 On photographing the spectrum only a very faint trace of scandium appeared. 



No. 2, monazite, contained 17 '15 per cent, of rare earths; the photographed 

 spectrum showed no scandium. 



No. 3, black wiikite, contained 22'58 per cent, of rare earths; the spectrum showed 

 considerable quantities of scandium. 



No. 4, brown wiikite, contained 2377 per cent, of rare earths ; the spectrograph 

 showed only a small amount of scandium. 



No. 5, wiikite, contained 24'85 per cent, of rare earths; the photographed spectrum 

 showed considerable quantities of scandium. 



A mixture of 99 '25 parts of scandium with 0'75 part of thorium would have an atomic weight of 

 45 5. 



