22 MR. CLIVE CUTHBERTOON AND MAUDE C0THBERTSON ON THE 



was 1-OU.M786. Seven of these were at room temperature and two at C. We 

 adopt -0003786 as the refractivity for the green mercury line. 



/L*ron.-F.ve experiments were made to determine the daemon. 



Thefbllowing table gives the mean results and compares the observed values with 

 those calculated from the formula 





)_ 2-9658x10" 

 ~ 



8135-3 



which was, as usual, calculated from the observations by the method of least 



squares : 



TABLE XII. Dispersion of Ammonia. 



NITRIC OXIDE. (NO.) 

 Previous Work. DUFET gives the following : 



Mr. K P. METCALFE, in collaboration with one of us,* obtained 293 '9 for \ = 5893. 



The gas used by MASCART had 10 per cent, of impurity. 



Preparation. Following the third method described by GUYE! we prepared the 

 gas by the action of of dilute sulphuric acid (10 per cent.) on dilute nitrite of soda 

 (6 per cent.) in a vacuum. After bubbling through concentrated sulphuric acid and 

 pawing over P,0 t it was condensed in liquid air and fractionally distilled. The gas 

 employed, tested with ferrous sulphate, showed less than 1 part in a 1000 of impurity, 



1 CtJTHBiBTsoN and E. P. METCALFK, ' Roy. Soc. Proc.,' A, vol. 80, p. 406, 1908. 

 t Gtmt, Mta. Soc. de Phys. ct d'Hiat. Nat. de Geneve,' vol. 35, p. 547, 1908. 



