Normal and Selective Pliotoelectric Effect. 



159 



alloy (69*4 per cent. K)'[10]. In fig. 3 the ultraviolet 

 end o£ the selective effect cannot yet be recognized ; but 







Fig 



. 3 



•— 



K- 



Na alloj 



r • 



polari 



zed li 



ght. 













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Wave-length 



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S 



eo 50 



t 



O 



Fig-. 4. — Potassium ; unpolarized light, 





































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1 



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A^200ju/j. 



Wave-length. 



this is easily seen in figs. 4 and 5_, which were observed on 

 K [14] and Rb [15] in unpolarized light, and show again 



