304 smithsonian miscellaneous collections vol. 52 



Absorption of the Rays. 

 By thin film of grease. 



Thin film on electrode reduced charge received 95%. After polishing 

 electrode with flannel, only 50% penetrated: Au2(3i4). 

 Length of rays increases with decreasing pressure ; visible rays may 

 be over 50 cm. long: 01(695, 43) ; Sm4(i09). 

 Reflection on Striking an Obstacle. 

 Diffuse: Au2(3i8). 



Per cent reflected is a function of the discharge potential, reaching a 

 maximum at a low potential: Fi(is6). 

 At 2,500 volts, more than 10% are reflected from Pt, Ag, or Cu : 



Fi(i5S). 

 At 600 volts, about 50% are reflected from Pt, Ag, or Cu : Fi(i56). 

 Reflection on glass wall produces thick bright layer when near enough to 



cathode: Rau 1(421). 

 Shown by Doppler effect in spectrum of light received by a slit at the 



end of tube: HK(566) ; 813(41, 423). 

 20 to 35% of H rays reflected: 813(41, 423). 



4. fluorescence excited. 

 On Glass Wall. 

 In air. 



Color shows great variations, even with same glass: Ws(524, 252). 

 Green, yellow, reddish yellow, and salmon observed : Gi (697,45) ; 

 G3(2ii); Ari(326); W2(io) ; W3(447) ; V3(i5) ; G4; 

 W5(524, 252). 

 Differences due to variations in gas filling: Ws(524, 252). 

 Color differs for deflectable and non-deflectable rays. 



Deflectable excite bright green fluorescence ; non-deflectable, 

 a weak yellow brown fluorescence: W4(432, 435); 

 W6(589); W9(675); Sm4(iii) ; 84(649). 

 In helium. Sodium light and green fluorescence: Rau 1(421). 



Deflected fluorescence blue: Rau 1(422). 

 In hydrogen. With pure H, fluorescence is pure green: W5(525, 255) ; 

 W6(59o) ; 84(649); Raui(42i). 

 With impure H, undeflected part is yellowish: W5(525. 255). 

 With potassium glass, fluorescence is weak blue: W5(525, 256). 

 In mercury vapor. Brownish or salmon red, no green: W5(525, 255); 

 W6(590); 84(649). 

 White?: SH(96). 

 In nitrogen. Sodium light persists in spite of all efforts to get rid of 

 oxygen: Rau 1(421). 

 Glass wall previously exposed to cathode rays, at first shows no 

 sodium light: Raul (422). 

 In oxygen. Brown fluorescence, no green: W5(525, 256); W6(59o) ; 

 84(649). 

 Sodium light alone appears after careful drying: Ram (421). 

 No fluorescence with potassium glass: W5(S25, 256). 



