Mr. W. M. Watts on the Spectra of Carbon. 101 



The readings of these lines on the scale of my spectroscope are 



Na&56; Na 7 ,75-5; NaS, 83*2; Nae, 43; 



the Fraunhofer lines C, D, and F reading 34*5, 50, and 90 re- 

 spectively. 



The same lines were observed by Huggins* in the spark taken 

 between sodium poles, and were shown to be due to sodium itself, 

 since they were obtained by the use of pure sodium-amalgam. 

 Diaconf obtained them from the flame of hydrogen which had 

 been passed through an iron tube in which sodium was volatilized. 



The sodium-spectrum obtained by means of a Bunsen burner 

 gives only the t> lines ; but if the temperature of the flame be 

 increased, these other lines become visible and in the order given 

 above. 



I find that Na/3 becomes visible almost precisely at the tem- 

 perature at which platinum melts. This, according to the ex- 

 periments of Deville, is 2000° C. 



The flame of hydrogen in air (of which the temperature, ac- 

 cording to the experiments of Bunsen, is 2024° C.) gives the D 

 lines only. The flame is incapable of fusing platinum except at 

 one point. 



The Bunsen flame of coal-gas and air gives only D. The 

 flame is incapable of melting platinum. 



The flame of coal-gas fed by a jet of air gives a spectrum in 

 which, besides D, the line Na /3 is faintly visible. This flame is 

 just capable of fusing a fine platinum wire. 



The flame of coal-gas fed by a mixture of oxygen and air (con- 

 taining about 30 per cent, oxygen and 70 per cent, nitrogen) 

 gives Na f$ distinctly and Na 8 faintly. Na 7 and e are not seen. 

 The flame fused platinum tolerably easily. 



The flame of coal-gas fed by pure oxygen gives a spectrum 

 containing Na /3, y, 8, and e, but e is only faint. The flame 

 fuses platinum easily. 



The flame of carbonic oxide in air (temperature 1997°, Bun- 

 sen) gives only the D line. It is incapable of melting platinum. 



Carbonic oxide fed by a jet of air still gives only D. The 

 flame just melts platinum. 



Carbonic oxide fed by oxygen (temperature of flame 3033° C, 

 Bunsen) gives Na /3 and y brilliantly. Na 8 and e were not seen. 

 The flame melts platinum easily. 



The flame of sulphur in air (calculated temperature 1900° C.) 

 gives the D lines only. It melts gold, but not platinum. 



The flame of sulphuretted hydrogen in air (calculated tempe- 



* Pogg. Ann. vol. cxxiv. p. 275. [Phil. Mag. 1864, vol. xxvii. p. 542.] 

 t Comptes RenduSf vol. lv. p. 334. 



