Manchester Memoirs, Vol. xlviii. (1904), No. 10 



X. On the Spectrum of the Glow Discharge at 

 Atmospheric Pressure. 



By G. A. Hemsalech. 



Communicated by Dr. C. H. Lees. 



Read February ibth. Received February 2jrd, igo4. 



I. — Production of the Gloiv Discharge. 



When the ordinary induction coil discharge is taken 

 in air, the electrodes being about one centimetre apart 

 for a lo-inch spark coil, a violet glow is seen near the 

 end of the negative electrode. When the electrodes are 

 brought very near together, the glow is seen at both 

 electrodes simultaneously.^ In this case the discharge of 

 the coil is oscillatory, the oscillations being very slow. 



The special interest which is attached to this glow is 

 the discovery recently made by Sir William and Lady 

 Huggins^ that radium, in an atmosphere of air at ordinary 

 pressure and temperature, spontaneously emits a spectrum 

 which coincides with or is very similar to that of the 

 negative glow as obtained in the ordinary coil discharge. 



This exceedingly interesting result induced me to try 

 a few experiments on the glow discharge at atmospheric 

 pressure, which, so far as I know, has received little 

 attention from spectroscopists. 



The glow discharge is obtained in a very striking 

 manner when the oscillations of a powerful condenser 

 discharge are slowed down by inserting a self-induction 



^ Lecoq de Boisbaudran, " Spectres Lumineux," p. 30. 

 * Sir William and Lady Huggins, Astroph. /ourn., vol, 18., pp. 

 151 cr' 390, 1903. 



March i8th, igo4. 



