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XXIV. 



PHOTOGRAPHS OF SPARK-SPECTRA FROM THE LARGE 

 ROWLAND SPECTROMETER IN THE ROYAL UNIVER- 

 SITY OF IRELAND. PART III. 1 : THE ULTRA-VIOLET 

 SPARK-SPECTRA OF PLATINUM AND CHROMIUM. 

 By W. E. ADENEY, D.Sc, A.R.C.Sc.L, Curator and Examiner 

 in Chemistry in the Royal University of Ireland. 



[Read, Mauch 19 ; Keceived for Publication, March 22 ; Published, Sept. 17, 1904.] 



The wave-lengths of the lines in the ultra-violet spark-spectra of 

 the metals platinum and chromium, which form the subject of 

 this communication, have been calculated from measurements 

 made from photographs of the first order of spectra, reproductions 

 of which have been published in Part I. of this work. 



The measurements have been made by means of a light 

 microscope, mounted on a stage which can be moved through 

 a space of about one inch long by a short micrometer screw. 

 Each line has been measured at least twice, and many of them 

 three and four times. 



Kayser's measurements 2 of well-defined lines in the arc- 

 spectrum of platinum have been employed for standards. The 

 conditions under which the photographs were obtained are 

 described in Part I., and it is only necessary to state that the 

 spectrum of platinum was derived from a pure specimen kindly 

 presented to the author by Messrs. Matthey and Johnson. The 

 chromium spectrum was obtained by sparking a saturated solution 

 of pure potassium chromate between platinum electrodes. 



In the cases where the calculated wave-lengths of the interme- 

 diate platinum lines have shown a close agreement with those by 



1 For Part I. see Trans. Roy. Dublin Soc, Vol. vn. (Ser. n.), 1901, p. 331, and 

 for Part II., see Sci. Proc. Roy. Dublin Soc, Vol. x. (N.S.), Part I., No. 3, 1903. 



2 Kayser, Konigl. Preuss. Akad. d. "Wissench. Berlin, 1897. 



SCIEN. PROC, R.D.S., VOL. X., PART II. IJ 



