REFRACTION AND DISPERSION OF THK HALOGENS, HALOGEN ACIDS, ETC. 23 



probably nitrogen. As the refractivity of nitrogen is almost identical with that of 

 nitric oxide the results were not modified by the impurity. The observations were 



T^ 7 f* 



reduced by the m-dinary formula /* 1 = (v 1) -- x . 



/ t) 



Refraction. Six can-fill double experiments (i.e., pressure rising and falling) gave 

 Experiment .... 1, 2, 3, 4, 5, 6. 



( M _1)K)' -2959, 2957, 2952, 2955, 2951, 2956. Mean 2955. 



We adopt this mean '0002955 as the value for the green mercury line. 

 Calculating the value for the I) line from this value and the dispersion formula 

 obtained below we find '0002944, which agrees well with 2939 found in 1908. 



Diapernon. From five observations the following values for the dispersion were 



obtained : 



TABLE XIII. Dispersion of Nitric Oxide. 



Using SELLMEYEK'S formula the results are expressed by 



D 3*5210 x 10" 



' K76) 122161 



NITROUS OXIDE. (N,O.) 

 Previous Work. DUFET gives 



