224 Mr. Gr. A. Hemsalech 11 : A Comparative Study 



§ 9. Observations on the Spectra of some other Element? 

 contained as Impurities in the Carbon Tube of the 

 Furnace. 



It is highly probable that all the foreign substances found 

 in the carbon of the furnace tubes are in the form of carbon 

 compounds, no doubt carbides, which are formed in the course 

 of the heating to which the tubes are subjected during the 

 process of their manufacture. The mode of excitation which 

 gives rise to the spectra emitted by these substances will 

 certainly be the same as that found for iron, namely dis- 

 sociation of the carbide through the action of heat. In 

 addition to sodium the presence of the following elements 

 has been particularly noted : — 



Relative Intensity at 



Element. 

 Al 



Wave-length. 

 r 394403 

 3961-54 



1500° C. 



00 



i 



2400° C. 

 6r 

 8r 



Ca 



3933-67 

 4226-72 

 4302-53 



4318-64 

 4435-32^ 



4454-78 



00 

 15 

 1 



00 



1 



Mn 



K.. 



Sr 



4030-80 

 4033-06 

 4034-48 



f 4044-15 

 1 4047-21 



4607-34 



Pb 



Cr 



4057-84 



4254-34 



4289-72 



000 



The appearance of the aluminium lines at so low a tempe- 

 rature as 1500° C. is most remarkable in view of the fact that 

 all attempts to obtain them in the air-coal gas flame have so 

 far proved unsuccessful. It may be that the carbide of 

 aluminium is more readily dissociated than those compounds 

 of this element which are generally employed in feeding 

 flames. 



