

THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. XXXYIII. — Carbon and Oxygen in the Sun * by 

 John Trowbridge. 



• In 1887 Professor Hutchins of Bowdoin College and myself 

 brought forth evidence to show that the peculiar bands of the 

 voltaic-arc spectrum of carbon can be detected in the sun's 

 spectrum. They are, however, almost obliterated by the over- 

 lying absorption lines of other metals, especially by the lines 

 due to iron. In order to form an idea of the amount of iron 

 in the atmosphere of the sun which would be necessary to 

 obliterate the banded spectra of carbon, I have compared the 

 spectrum of carbon with that of carbon dust and a definite 

 proportion of iron distributed uniformly through it. The car- 

 bon dust and iron reduced by hydrogen was formed into pencils 

 suitable for forming the voltaic arc* Chemical analysis showed 

 that the iron was uniformly mixed with the carbon dust. Speci- 

 mens, taken from different sections of the carbons which I 

 burned in the arc, gave twenty-eight per cent of iron and 

 seventy-two per cent of carbon. 



The method of experimenting was as follows: That portion 

 of the spectrum of the sun which contains traces of the pecu- 

 liar carbon band lying at wave length 3883*7 and which has 

 been almost obliterated by the accompanying lines of absorp- 

 tion of other metals, among them those of iron, was photo- 

 graphed. The pure carbon banded spectrum was photographed 

 on the same plate immediately below the solar spectrum, and 

 the spectrum of the mixture of iron and carbon immediately 

 below this. The sun's spectrum can be regarded as a com- 



*I am indebted to Mr. John Lee of the American Bell Telephone Co. for his 

 skill in making the carbons and for analyses of the composite carbons. 



Am. Jour. Soi. — Fourth Series, Yol. I, No. 5. — Mat, 1896. 

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