[ 607 J 



XXXIX. 



ON THE INFLUENCE OF SELF-INDUCTION ON THE SPAEK 

 SPECTRA OF CERTAIN NON-METALLIC ELEMENTS. 



By GENEVIEVE V. MORROW, A.R.O.Sc.I. 



[communicated by JAMES H. POLT.OK, D.SC] 



(Plates XLVIII-LI.) 



[Read June 25, 1912.1 Published May 19, 1913.] 



The spark spectra of the metallic elements have been obtained under 

 a great variety of conditions, and the wave-lengths of the ultimate lines have 

 been determined with accuracy ; but we have not a sufficient knowledge of 

 the lines that arise from the non-metallic elements when small quantities of 

 these are present in the atmosphere surrounding the electrodes at the time 

 of sparking, and for analytical purposes it is very important that this should 

 be known. 



In sparking substances it is sometimes desirable to use a self-induction 

 coil and sometimes not, so that it is important to know also the effect of 

 self-induction on the development of the lines due to the substance present 

 in the atmosphere surrounding the electrodes. 



In the present investigation I have endeavoured to obtain the spectra 

 of some of these elements under atmospheric pressure, and whilst so doing 

 have studied the changes caused by introducing a self-induction coil into 

 the secondary circuit. 



The effect caused on the spark spectra of the metallic elements by 

 introducing a self-induction coil into the secondary circuit was first studied 

 by Schuster and Hemsalech,^ and they found that self-induction removed 

 the air- lines from spectra. Their explanation of this phenomenon was that 

 the air-lines were caused by the initial discharge when the spark-gap 

 contained no metallic vapour. Subsequently the discharge passed through 

 the vapourized metal which had diffused away from the electrodes. On 

 inserting the self-induction coil the discharge passed more slowly, the air 

 did not become sufficiently heated to yield its spectrum, and the discharge 



1 The publication of this paper waa unavoidably postponed. — J. H. P. 



2 Phil. Trans. Roy. Soc, 1900, vol. cxciii., Ser. A., p. 189. 



SCIENT. PKOC, R.D.S., VOL. XIII, NO. XXXIX. 4 X 



