502 Prof. H. Crew on the 



Table II. 



Spectrum of Zinc Arc as modified by an Atmosphere of 

 Hydrogen. 



Wave-lengths of lines which 

 are relatively 



Intensified. Weakened. Unaffected, 



5182-20 



2558-03 

 2502-11 



4630-06 



4298-54 

 4293-02 

 410194 



[3683 63] 



[3639-72] 



3075-99 



2781-33 



4810-71 

 4722-26 

 4680-38 



3315-26 

 3346-04 



3345 62 



3345-13 

 3303-03 

 3302-67 

 3282-42 



3072-19 

 3035-93 

 3018-50 



2801-00 



[277T05J 



2770-94 

 2756-53 



[2751491 

 [2736-96] 



2712-60 

 2684-29 

 2670-67 



[2623-87] 



2608-65 

 2582-57 

 2570-00 



Eemarks. 



Second Subordinate Series. 



Shading towards red greatly increased^ 



Too faint for reliable comparison : 

 apparently weakened. 



"j Two very persistent lead-lines which, 

 I as impurities, are greatly weakened 

 ] by hydrogen. 



Not strong enough for comparison. 



First Subordinate Series. 



Second Subordinate Series. 



Not found. 



No trace of these lines in hydrogen. 



Second Subordinate Series. 



Invisible in hydrogen. 



1 Last triplet visible on hydrogen nega- 

 j tive after two hours' exposure. 



I Strong spark-lines. 



