1895.] 



Constituent of certain Minerals. 



87 



had to content myself with throwing the two spectra into the same 

 field of vision. By using two coils and adjusting current until the 

 luminosity of the common lines in the two tubes becomes equal, very 

 accurate conclusions can be drawn regarding the spectra. 



A description has already been given of the first sample of gas 

 examined (see Preliminary Note). In all probability a considerable 

 amount of air had leaked in during its extraction, for it showed 

 practically the whole of the argon spectrum in addition to lines to be 

 ascribed to helium. 



The gas prepared on a large scale, which consisted chiefly of 

 hydrogen, was first examined. There is nothing in the spectrum 

 which calls for special notice, unless it be that the helium yellow (D : ,) 

 and violet lines were visible, even in presence of 80 per cent, of 

 hydrogen. These and other helium lines were brought out more 

 intensely after a large portion of the hydrogen had been removed by 

 means of palladium. The argon red pair were, however, invisible in 

 the helium-tube. 



On sparking this gas, all hydrogen and nitrogen were removed. 

 And after a vacuum-tube had been filled a careful comparison was 

 made between the spectrum of this gas and that of argon. 



Comparison of the Spectra of Helium and Argon. 



