and some of its Compounds. 315 



350° C, the same two lines appeared, and in addition the fol- 

 lowing very faint lines : 



3871 

 3886 



These same four lines also appear in carbon tubes when filled 

 with oxygen. In addition, the following lines are present : 



3936 

 3971 



4077 



All these lines appear in the nitrogen tube, and in addition : 



3883 

 3876 

 3868 

 3856 

 3849 

 3841 



None of these lines appear in tubes with metallic electrodes 

 filled with nitrogen ; and they are therefore not nitrogen 

 lines. All the lines in the nitrogen tube are more intense 

 than those in the oxygen tube, and it is possible that with a 

 longer exposure these additional lines would come out in the 

 oxygen. 



To study the effect of the carbon terminals, the following 

 gaseous compounds were put into wide tubes provided with 

 copper terminals and rendered luminous by condenser dis- 

 charges : 



Cyanogen 



Carbon monoxide 



Carbon dioxide 



Acetylene. 



Cyanogen was prepared by heating mercuric cyanide and pass- 

 ing the gas over sulphur to remove any traces of mercury 

 vapor. Carbon monoxide was prepared by heating potassium 

 oxalate with concentrated sulphuric acid and passing the gas 

 over potassium hydroxide, and collecting over water. Carbon 

 dioxide was prepared by treating potassium carbonate with 

 dilute sulphuric acid and collecting over water. All of these 

 gases were allowed to remain in contact with pentoxide before 

 introduction into the tubes. 



With acetylene, carbon monoxide, and carbon dioxide, con- 

 denser discharges being employed, the results appear to be 

 identical with those obtained with hydrogen in the tube with 

 carbon electrodes. With cyanogen the same lines appear ; and 

 in addition, the bands which are characteristic of these gases 



