3t50 



Dr. L. Hleekrode. On the Determination of the 



The hydrobromic and the hydriodic acid do not figure in the table, 

 as their index of refraction in the gaseous state has not been ascer- 

 tained at present. As I examined, however, the index of refraction 

 of liquid bromine* and of liquid chlorine, and as the equivalents of 

 refraction of their combinations with hydrogen may be calculated 

 from my experiments with the liquefied acids, I add here the results, 

 as they can help to elucidate a question suggested by Professor Glad- 

 stone, in his former investigation on the refraction equivalents of the 

 elements, f and relating to that of hydrogen especially. 



Refraction Equivalent of the Halogens and of their Combinations with 



Hydrogen. 



The columns headed with the term " calculated " contain the 

 values^ that are obtained by addition of the refractive equivalents of 

 the combined atoms ; for H and Cl they are given in the paper of 

 Landolt (already alluded to), for both expressions ; for Br and I they 

 were calculated by myself. Next to this column are placed the 

 corresponding values of the substances, deduced directly from the 



substance compared in liquid and gaseous condition, and that both were only 

 approximative. 



* The determination of the index of liquid bromine will be described in the next 

 chapter, and it was ascertained to be 1'571. 



t Gladstone : " Proc. Roy. Soc.," vol. 16, p. 443. 



t I calculated the value of iodine for the 3 formula with the value given in the 

 " Physik. u. Chem. Tab. " of Bornstein u. Landolt as the index for the D line 

 1-51307, and the density, at 20, 1'9305. 



