XV111 CONTENTS 



416. Media for determinations of refractive indices with the microscope : 



Permanent standard resinous media, ;; d (o.589/a) = 1.546 to 1.682. 375 



417. Media for determinations of refractive indices with the microscope : 



Substances, w D = 1.39 to 1.75 375 



Reflecting Powers 



418. Light reflected when light is normal to surface 376 



419. " n is near unity or equals i+dn 376 



420. " " »-i.5S 376 



421. Optical constants of metals 377 



422. " " " " (additional data) 378 



423. Reflecting power of metals 378 



424. " : Perpendicular incidence and reflection. 379 



425. Percentage diffuse reflection, from miscellaneous substances . . . 379 



426. reflection from metals, violet end of spectrum .... 380 



427. Ultra-violet reflecting power of some metals 380 



428. Infra-red reflectivity of tungsten (temperature variation) .... 380 



429. Percentage reflecting power of dry powdered pigments 381 



430. Infra-red diffuse percentage reflecting powers of dry pigments . . 381 



431. Reflectivity of snow, sand, etc 381 



432. Reflecting power of powders (white light) 382 



433. Variation of reflecting power of surfaces with angle 382 



434. The reflecting power of building materials 383 



435 

 436 

 437 

 438 



439 

 440 

 441 



442 



443 

 444 



445 

 446 



447 

 448 



449 

 450 

 45i 



45 2 

 453 



Transmissive Powers 



Light filters, narrow spectrum regions 384 



Absorbing power of various materials — infra-red 384 



Transmissibility of radiation by dyes 385 



" " Jena glasses 386 



" " " " " colored glasses 386 



" " " ultra-violet glasses .... 387 



" American glasses 387 



Transmission of various lights through colored glasses 388 



Ultra-violet transparency (302 m/x) 2>^> 



(a) Ultra-violet transparency atmospheric components 389 



(b) Atmospheric transparency for ultra-violet 389 



Penetration ultra-violet light into sea water 389 



Transparency of the various substances of Tables 394 to 402 . . . 390 



Color screens [Landolt] 39 1 



[Wood] 39 1 



Transmission percentages of radiation through moist air 392 



Transparency of water vapor (steam) 392 



" water 39 2 



Infra-red transmission and absorption : Gases, 6.7 to 32.8//, .... 393 



Solids, 6.7 to 32.8^ .... 393 



