Section III, 1918 [65] Trans. R.S.C. 



New Lines in the Extreme Ultra-Violet of Certain Metals. 



By D. S. AiNsi.iE, M.A., and D. S. Fuller, M.A. 

 University of Toronto. 



Presented by Professor E. F. Burton, Ph.D., F. R.S.C. 



(Read May Meeting, 1918.) 



The experiments described below form an extension of the recent 

 work of Lyman,^ Handke,^ Wolff,^ and Saunders*, on the extreme ultra- 

 violet region. 



By using a fluorite vacuum spectroscope and a vacuum arc lamp, 

 photographs of spectral lines were obtained free from the disturbance 

 due to the absorption of the light by glass, quartz or air. The arc 

 could be manipulated from the outside of the case of the spectro- 

 graph; the current ranged from four to fifteen amperes, according to 

 the metal used. 



For the hard metals with high melting points the terminals 

 of the arc were made of the metal; when a soft metal was used, the 

 terminals were made of iron and were hollowed out in a cup-shaped 

 cavity in which the metal sample was placed. 



The whole apparatus was connected up by a lead pipe to a set 

 of trimount oil pumps in series, so that it could be quickly evacuated. 

 The vacuum was tested by having a discharge tube sealed in by a 

 side connection. The vacuum used when photographs were being 

 taken was that which gives a dark, green discharge. 



A hydrogen discharge tube fitted with a fluorite window was 

 arranged in the apparatus, so that on one and the same plate there 

 could be obtained both the hydrogen spectrum and the spectrum of 

 any given metal in the same region. By adjusting the cover slit, a 

 photograph of the gas spectrum could be obtained on the bottom of the 

 plate, and then, without moving the plate, the cover slit could be 

 readjusted, the discharge tube could be replaced by the vacuum arc 

 lamp, and thus the spectrum of the metal could be thrown on the same 

 plate just above the hydrogen spectrum. This afforded a means of 

 comparing each metal spectrum with that of the gas. 



^ Lyman: Spectroscopy of the Extreme Ultraviolet (Longmans). 



2 Handke: Inaug. Diss. Berlin., Aug. 1909. y^ç \{)Â7''\ 



3 Wolff: Ann. de. Phys. 42 p. 825, 1913. A ^ 1 /\^ /^x 



* Saunders: Astro phys. Jour. 43, p. 234, 1916. J\ 



