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XL 



PHOTOGRAPHS OF SPARK SPECTRA FROM THE LARGE ROWLAND 

 SPECTROMETER IN THE ROYAL UNIVERSITY OF IRELAND. 

 PART I. THE ULTRA-VIOLET SPARK SPECTRA OF IRON, COBALT, 

 NICKEL, RUTHENIUM, RHODIUM, PALLADIUM, OSMIUM, IRIDIUM, 

 PLATINUM, POTASSIUM CHROMATE, POTASSIUM PERMANGANATE, 

 AND GOLD. By W. E. ADENEY, D.Sc, A.R.C.Sc.I., Curator and Examiner 

 in Chemistry in the Royal University of Ireland, Dublin. 



(Plates XXVII. and XXVIII.) 



[Read Apeh 17, 1901.] 



Introduction. 



Peculiarities in the constitution of s2Dark spectra of the elements were first 

 described in the Scientific Transactions of this Society.* 



The photographs were taken with the first spectrograph constructed, which 

 admitted of the whole of the spectra being included on one plate and extending 

 from wave-lengths 4700 to 2000. The method of photographing, and the con- 

 struction of the instrument, were described in a paper published by this 

 Society, t 



In " Notes on certain Photographs of the Ultra- Violet Spectra of Elementary 

 Bodies,"^ it was shown that when the elements were classified along with their 

 spectra in well-defined groups, according to the periodic law, there were marked 

 characteristics which were shown to belong to distinctive groups of the elements. 

 These peculiar characteristics of the lines were length and continuity from pole to 

 pole, with emissive power of intensity of chemical action, extension above and 

 below the points of the electrodes, the nimbus or aureole, sharpness or diffuseness, 

 and the background of continuous rays. The features of the lines were correlated 

 with the chemical and physical properties of the elements, such as conductivity, 



* Hartley, vol. i., p. 231, 1881. 



t Sci. Proc. Eoy. Dublin Soc, vol. iii., ser. 2, p. 93, 1881 (Hartley). 



f Journ. Chem. Soc, vol. xliii., p. 384, 1882 (Hartley), and " On Homologous Spectra" {ho. cit., vol. 

 xliii., p. 390, 1883, by the same author). 



TKANS. ROY. DUB. SOC, N.S., VOL. VII., PART XI. 3 A 



