vi.] HOFMANN'S RESULTS. 79 



Herr K. Hofinann, 1 his assistant, continued these researches 

 on both sides of the region observed by Kirchhoff, that is as 

 far as A on one side and G on the other, and in addition he 

 investigated the spectra of the following metals: Potassium, 

 rubidium, lithium, cerium, lanthanum, didymium, platinum, 

 palladium, and an alloy of iridium and ruthenium. Hofmann 

 added the following coincidences between lines of the spectra 

 of these chemical elements and the dark solar lines : ' * : 



Lines. Lines. 



Calcium ... 16 Chromium . . 



Barium ... 5 Nickel .... 4 



Strontium. . . 2 Cobalt .... 4 



Magnesium . . Zinc .... 3 



Copper .... 1 Cadmium ... 2 



Iron .... 31 Gold .... 1 



The spectra of the additional metals examined gave the following 

 coincidences : 



Lines. Lines. 



Cerium. ... 2 Palladium .... 2 



Didymium . . 2 Platinum 1 



Lanthanum . . 1 Rubidium and Iridium 1 



The potassium spectrum could not be obtained by moistening 

 the electrodes with salts of this metal, and when poles of the 

 metal were employed the spectrum was so very feeble that 

 only two prisms could be employed, and hence the position of 

 the lines with regard to the solar lines was not easily deter- 

 mined. He noted that the line Ka was better seen if the 

 Bunsen flame was used instead of the electric spark. 



Kirchhoff and Hofmann pointed out how the latter work con- 

 firmed the results of the previous examination. A large number 

 of lines of iron and of calcium occur in the yellow and the 

 blue, and all these were found coincident with well- denned 

 Fraunhofer lines. The probability that nickel was present in 



1 KirchhofTs Researches, translated by Roscoe, part ii., Appendix. 



