vn.] SULAK COINCIDENCES. 89 



The following is a summary of the coincidences observed : 



Barium. . . 11 (of 26) Zinc .... 2? (of 27) 

 Aluminium . 2 ? (of 14) Copper .... 17 



Angstrom remarks that the number of these lines, about 800, 

 might easily be increased by raising the metals to a higher 

 stage of incandescence. Still, he observes, the number already 

 found is quite sufficient to enable him to refer the origin of 

 almost all the stronger lines of the solar spectrum to known 

 elements, thus confirming the opinion he had expressed in a 

 previous memoir, that the substances which constitute the mass 

 of the sun are doubtless the same as those forming that of the 

 earth. But, he writes, the fact must not be lost sight of that 

 there exist nearly midway between F and G strong solar lines, of 

 which the origin is entirely unknown. 



Angstrom \ gives no list of elements present in the sun such 

 as that given by Kirchhoff, but in its place the table of coin- 

 cidences printed above. Thalen, his associate, in a separate 

 memoir, 2 gives, however, as present in the sun 



Sodium, Chromium, Hydrogen, 



Iron, Nickel, Manganese 



Calcium, Cobalt, Titanium, 

 Magnesium, 



thus rejecting zinc, barium, and copper from Kirchhoff s list 

 of accepted elements, adding cobalt from the doubtful list, and 

 hydrogen and manganese from Angstrom's, and titanium from 

 his own observations. 



1 Recherches sur le Spectre Solairc, par A. J. Angstrom. Spectre Normal du 

 Soldi. Berlin, 1869. 



2 Longueurs d'Ondc des Raies Metalliqucs, p. 11. Nova acta. Upsala, 1868. 



