TABLE 554.— INDEX OF REFRACTION OF GASES AND VAPORS 



533 



A formula was given by Biot and Arago expressing the dependence of the index of refraction 

 of a gas on pressure and temperature. More recent experiments confirm their conclusions. The 



formula is n< — 1 = Mo — £- , where n t is the index of refraction for temperature t, n for 



1 + at 760 

 temperature zero, a the coefficient of expansion of the gas with temperature, and p the pressure 

 of the gas in millimeters of mercury. For air see Table 553. 



Indices of refraction 



Kind of 

 Substance light 



Acetone D 



Ammonia white 



D 



Argon D 



Benzene D 



Bromine D 



Carbon dioxide . . . white 

 ... D 



Carbon disulfides W pv 



Carbon monoxides , •. 



Chlorine white 



D 



Chloroform D 



Cyanogen white 



D 



Ethyl alcohol .... D 



Ethyl ether D 



Helium D 



Hydrochloric f white 



acid I D 



The values are for 0°C and 760 mmHg 



Kind of 



Indices of refraction Substance light Indices of refraction 



1.001079-1.001100 Hydrogen white 1.000138-1.000143 



1.000381-1.000385 " D 1.000132 



1.000373-1.000379 „ . .... / D 1.000644 



1.000281 Hydrogen sulfide, j D ^^3 



1.001700-1.001823 Methane white 1.000443 



1.001132 " D 1.000444 



1.000449-1.000450 Methyl alcohol .. . D 1.000549-1.000623 



1.000448-1.000454 Methyl ether D 1.000891 



1.001500 Nitric oxide white 1.000303 



1.001478-1.001485 " " D 1.000297 



1.000340 Nitrogen white 1.000295-1.000300 



1.000335 " D 1.000296-1.000298 



1.000772 Nitrous oxide .... white 1.000503-1.000507 



1.000773 " " .... D 1.000516 

 1.001436-1.001464 Oxygen white 1.000272-1.000280 



1.000834 " D 1.000271-1.000272 



1.000784-1.000825 Pentane D 1.001711 



1.000871-1.000885 Sulfur dioxide . . . white 1.000665 



1.001521-1.001544 " " ... D 1.000686 



1.000036 Water white 1.000261 



1.000449 " D 1.000249-1.000259 



1.000447 



SMITHSONIAN PHYSICAL TABLES 



