LIGHT. 



(42) REFRACTIVE INDICES CHIEFLY FOR THE MEAN D LINE. 



Sottds. 



Lead chromate 2'5? 



Diamond 2'42 



Phosphorus 2'22 



Native sulphur 2*04 



Lead borate 1'86 



Ruby 1-71 



Iceland spar (ord.) 1'658 



,, (ext.) 1-486 



Topaz 1-61 



Flint glass 1'6 



Emerald 1'58 



Quartz (ord.) 1-544 



(ext.) 1-553 



Rock salt 1-54 



Resin 1'54 



Citric acid 1'53 



Canada balsam 1*53 



Felspar T52 



Potassium nitrate 1 '52 



Potassium sulphate 1*51 



Ferrous sulphate 1 '5 



Crown glass 1-5 



Magnesium sulphate ... 1-49 



Fluor spar 1-43 



Ice 1-31 



Liquids. 



Phosphorus 2*075 



Carbon disulphide 1'63 



Oil of bitter almonds ... 1'6 



Oil of cassia 1'58 



Aniline 1'57 



Phenol 1-55 



Nitrobenzene 1'54 



Benzene 1'49 



Glycerin 1 '47 



Turpentine 1'46 



Chloroform 1'44 



Sulphuric acid 1*42 



Alcohol (amy!) 1*4 



Alcohol (ethyl) 1 '36 



Ether (ethyl) 1'35 



Water 1*33 



Alcohol (methyl) 1'33 



Gases and Vapours (white light}. 



Air 1-000294 



Oxygen 1*000272 



Hydrogen 1-000138 



Nitrogen 1 0003 



Chlorine 1-000772 



Nitrous oxide 1-000503 



Nitric oxide 1 '000303 



Hydrogen chloride ... 1 '000449 



Carbon monoxide 1-000340 



Carbon dioxide 1-000449 



Cyanogen 1-000834 



Marsh gas 1*000443 



Olefiant gas 1 '000678 



Ammonia 1-OOOC85 



Carbonyl chloride 1 '001 159 



Hydrogen sulphide ... 1-000644 



Sulphur dioxide 1 '000665 



Sulphur 1-001629 



Phosphorus 1-001364 



Arsenic 1-001114 



Mercury 1 '000556 



(43) ROTATORY POLARISATION. 



The amount of rotation very nearly varies inversely as the square 

 of the wave-length of the light used. 



In the case of the solution of an active substance in an 

 inactive liquid the "specific rotation for light" of wave-length x. 



[a]* = X v where a is the observed angle, v the volume of 

 Iw 



