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XXII. 



THE ULTIMATE LINES OP THE VACUUM-TUBE SPECTRA 

 OF MANGANESE, LEAD, COPPER, AND LITHIUM. 



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



[communicated by JAMES H. POLLOK, B.SC] 



(Plate XXIV.) 



[Read Febkuaey 27. Published May 11, 1912.] 



Recent advances in spectrum analysis liave made it desirable that we should 

 have au accurate knowledge of the ultimate lines of vacuum-tube spectra, as 

 so far no accurate determinations of this kind have been made ; and without 

 a knowledge of the ultimate lines of the elements, it is often impossible to 

 determine with certainty the origin of the lines of a complex spectrum. It 

 has long been known that veiy minute quantities of certain elements give 

 brilliant spectra in vacuum-tubes, often to the exclusion of the spectra of 

 substances present in large quantities, so that it is also desirable to have an 

 accurate knowledge of the absolute quantity of each element necessary to 

 develop a particular spectrum under given conditions. The following 

 investigation has been undertaken to determine these two points in respect of 

 the elements manganese, lead, copper, and lithium. 



The spectra of most of the elements have been obtained under various 

 conditions, and the wave-lengths of the lines determined with accuracy. 

 Quantitative analysis by means of the spectroscope was first successfully 

 applied by Sir Walter Noel Hartley' to the spark-spectra of the elements, 

 and he investigated the quantitative spectra of many substances by sparking 

 solutions of known concentration, and has tabulated the lines which appear 

 when certain percentages are present. This work was continued by 

 Drs. PoUok and Leonard,^ who determined the quantitative spark-spectra 

 of all the remaining common elements, and of many of the rare elements. 

 Investigations of this kind have also been made by M. de Gramont and 

 others, so that our knowledge of the quantitative spectra and ultimate lines 

 of the spark-spectra is now fairly complete. 



Sir Walter Hartley also indicated the importance of the persistency of 



1 Phil. Trans. Eoy. Soo., 1884, vol. clxxv.. Part ii, pp. 325-342. 



- Scient. Proc. Roy. Dub. Soc, 1907-1908, vol. xi., pp. 217-236, 257-279, 331-337. 



SCIENT, PROC, K.D.S., VOL. Xnl., NO. XXII, 2 T 



