[mclennan-edwards] absorption SPECTRA OF MERCURY 177 



II. In the absorption spectrum of non-luminous cadmium vapour 

 there is a strong symmetrically spaced absorption band at A = 2288 

 A°.U. and a narrow sharply defined one at A = 3260- 17 A°.U. 



III. In the absorption spectrum of non-luminous zinc vapour 

 there is a strong symmetrically spaced absorption band at = A 2139-3 

 A°.U. and a very narrow, sharply defined* one at A = 3075-99 A°.U. 



IV. With the exception of the absorption band at A = 2338 A°.U. 

 all the absorption bands found for the vapours of the three metals 

 are the first members of either the series represented by n = 1-5, 

 S — m, P or that represented by n = 2, p2 — m, S. 



V. No absorption bands were found in the absorption spectra 

 of gold, silver and copper vapours and in those of the vapours of 

 alloys of these metals. 



VI. A new form of metallic vapour arc lamp has been devised 

 which gives arcs of exceptional brilliancy. 



VII. In the arc spectrum of cadmium, reversals were found at 

 A = 2288-79 A°.U. and A = 3100 A°.U. 



VIII. An examination of the cadmium arc line A = 6439-3 A°.U. 

 with a Lummer plate interferometer showed it to be simple and with- 

 out satellites. The zinc line A = 6364 A°.U. photographically was 

 found to be a simple one but visually it appeared at times to be ac- 

 companied by two faint satellites. 



IX. A number of new lines have been found in the spark spectrum 

 of cadmium between A = 2100 A°.U. and A = 1840 A°.U. These 

 were Ijrought out by the use of a fluorite spectroscope. 



We desire to acknowledge our indebtedness to Mr. P. Blackman 

 for assisting us in taking the photographs. 



The Physical Laboratory, 

 University of Toronto, 

 May 1st, 1915. 



