54 MR. A. FOWLER ON THE SPECTRUM OF SCANDIUM, 



lines, 5210'7, 5219 - 7, and 5375'5, all of which were given as scandium lines by 

 THALEN, Sir NORMAN LOCKYER has kindly informed me that weak lines in these 

 positions were found on the Kensington photographs, but not included in the published 

 list. The line at 52 10 '7 was almost masked by the shading from the strong silver 

 line 5209 - 6 arising from the silver poles employed for the arc, and this probably 

 accounts for its being passed over. In the case of 52 19 '7 the line was marked on the 

 photograph as an impurity, but the record as to the substance to which it was 

 attributed has been misplaced. The third line, 5375'5, was omitted as being possibly 

 due to thorium, for which THALEN gives a fairly strong line at 5374 '6, or 5375 '6 when 

 corrected to ROWLAND'S scale. A photograph of the thorium spectrum, taken for the 

 purpose, shows that the line in question is not truly coincident with the thorium line. 

 There accordingly seems to be no sufficient reason why these three lines should not lie 

 regarded as part of the scandium spectrum. 



Flutings. 



In addition to the line spectrum, all the photographs, with the exception of those 

 of the arc in hydrogen, show a fluted spectrum which is especially strong towards the 

 red end, but extends also into the green and blue-green. Several of these flutings 

 have previously been noted in the spark spectrum by THALEN, who regarded them as 

 being probably due to the oxide of scandium and not to the metal itself. The complete 

 disappearance of the flutings when the arc is passed in hydrogen tends to confirm 

 THALEN'S view that they originate in the oxide, but no further research on this point 

 has yet been undertaken. 



A list of the flutings, all of which fade away towards the red, is given in Table III. 

 An attempt has been made to include all the fainter heads as well as the bright ones, 

 but some of the heads are rather diffuse and the positions consequently somewhat 

 uncertain. 



By far the brightest group of flutings is in the orange-red, beginning at 6017'3, and 

 there are fainter groups beginning at G4087 and 5737 '2. There are no flutings in 

 the middle green, but three rather feeble flutings, showing structure lines over a long 

 range, begin at 4G72'8, 4858'2, and 5133'8. No flutings have been found in the blue 

 and violet. 



In the sunspot spectrum there is a hazy line about 6036 '6 which may perhaps 

 correspond with the brightest scandium fluting measured as 6036 '48, but as the other 

 bright heads cannot certainly be traced (partly on account of Fraunhofer lines) the 

 evidence as to the presence of scandium oxide in spots is very slight. 



Comparison with the Solar Spectrum. 



Several important additions to ROWLAND'S identifications of solar lines with 

 scandium were made by LOCKYER and BAXANDALL, and other possible coincidences 



