The Senes Spectrum of Mercury, 



637 



absorption than quartz which calcite exerts in this region 

 (X2500). An exposure of eight hours through the calcite 

 prisms gave no greater effect than half an hour through the 

 quartz. 



The following are the wave-lengths and frequencies of the 

 lines of the series obtained by comparison with the iron arc 

 (Kayser, B. A. Report, 1891). The first components only of 

 the triplets are given : the series formed by the two other 

 components are also well developed, but the higher lines in 

 them lie beyond the region in which quartz is fairly trans- 

 parent, and require very long exposures to bring them out : 





Diffuse 



Series. 



Sharp Series. 



m. 



X (air). 



n (vac). 



X (air). 



n (vac). 



2* ... 



f 366346 



63-05 



5500 



L 5031 



272890 ) 

 292-1 I 

 352- 1 f 

 387 -3 J 



5460-97 



18306-8 



3* ... 



f 3027 66 



25-79 



1 23-64 



( 21-68 



33019-4^, 

 039-8 

 063-3 

 084-8 J 



3341-70 



29916-5 



4*... 



2803-69 



35657-0 



2925-51 



34172-3 



5* ... 



269974 



37029-9 



275983 



36223-6 



6 



2639 92 



37868-9 



267520* 



37369-5 



7 



260310 



38404 5 



2625-37 



38078-7 



8 



257834 



38773-2 



2593-43 



38547-7 



9 



2561-15 



39033-5 



2571-85 



38871-0 



10 .... 



2548-51 



39227-1 



255636 



39106-6 



11 



t 





2545-09 



39279-8 



12 



2531-74 



39487 



t 





13 



2525 90 



39578 2 



2529-47 



39522-3 



14 



252127 



39650 9 



2524-48+ 



39600-5 



15 



2517 57 



39709 2 







16 



2514-48 



39758 







* Kayser, Spectroscopic, vol. ii. p. 545. 



t Hidden by the over-exposed strong line, X25367. 



\ Kayser and Runge give a weak line 2524-80 (B. A. Rep. 1892). 



An exposure of two hours with the quartz prism gave also 

 a series of converging lines which was evidently a con- 

 tinuation of the principal series which starts in the ultra-red. 



