118 Dr. W. Marshall Watts on the Spectra 



Morren * undertook experiments to prove that Attfield 

 was wrong, but became convinced that he was right. He 

 obtained the spectrum bj burning cyanogen in oxygen, and 

 also by taking the spark in cyanogen or acetylene at atmo- 

 spheric pressure. 



Pliicker and Hittorf f, Huggins J, Wiillner§, and Salet || 

 all arrive at the same conclusion as Attfield. Schuster ^[ in 

 his Report o£ the Committee of the British Association 

 " On the Present State of our Knowledge of Spectrum 

 Analysis," wrote in 1880: — " On the whole it may be said that 

 from the publication of Attfield's paper until the year 1875 

 every spectroscopist, whether he was a chemist or a physicist, 

 who had set to work to decide the question, came to the 

 conclusion that the candle spectrum was a true spectrum 

 of carbon, and the question appeared to be settled. In the 

 year 1875, after Angstrom's death, Thalen published a 

 paper ** in which he describes some experiments made 

 jointly with Angstrom. In consequence of these expe- 

 riments the authors expressed the opinion that the candle- 

 spectrum was due to a hydrocarbon. The experiments 

 which they gave in support of their view were made by 

 taking the spark of carbon electrodes in various gases, and 

 examining the spectra of the ' aureole ' or ' glory ' as it 

 might be called. If the spark is taken in oxygen, the 

 undoubted spectrum of carbonic oxide appears; in hydrogen 

 the candle-spectrum is seen; and in nitrogen some blue and 

 violet bands are added to the candle-spectrum which appear 

 to be duo to a compound of carbon and nitrogen. As it is 

 known that o acetylene is formed when the spark is taken in 

 hydrogen, Angstrom and Thalen conclude that the spectrum 

 seen in the * glory ' is due to acetylene." 



The theory of Angstrom and Thalen, that the " Swan " 

 spectrum is due to a hydrocarbon, was adopted and main- 

 tained by Liveing and Dewar|f. They examined the spectra 

 seen in the electric arc between carbon poles in air, hydrogen, 

 nitrogen, chlorine, carbonic acid, carbonic oxide, nitric oxide, 

 and ammonia, and found that the green and blue bands of 

 the " Swan " spectrum, well seen in hydrogen, less strong in 



* Morren, Ann. Chim. Phys. iv. p. 305 (1865). 



t Pliicker and Hittorf, Phil. Trans, civ. p. 1 (1865). 



I Huogms, Phil. Trans, clviii. p. 558 (1868). 

 § Wiillner, Po#£. Ann. cxliv. p. 481 (1872). 



II Salet, Ann. Chim. Phys. xxviii. p. 60 (1873). 

 H Schuster, B. A. Rep. 1880. 



** Angstrom and Thalen, JSova acta Reg. Soc be. Upsal. ix. (3) (1875). 

 tt Liveing and Dewar, Proc. Boy. Soc.'xxx. pp. 152, 494 (1880). 



