270 



Rev. T. P. Dale on a Relation between the 



difficulty they require a numerous and bulky array of 

 figures which must be carefully verified and checked, and 

 also because more data are needed. It is also unfortunate 

 that no data exist, which are accessible to me, of the absorp- 

 tion-spectra of chlorine, bromine, or iodine, or of sulphur 

 and selenium, comparable with the observations here used 

 as the basis of the calculations in the Table. It is in the 

 hope that some of these data may be supplied that I venture 

 to put this paper before the Society. 



Some interesting relations are observable between the 

 equivalents and refractions'* of gaseous elements and com- 

 pounds, which I hope to present in a future paper. 



Note. — The data are taken from Prof. Everett's ' Units and Physical 

 Constants,' 2nd ed. 1886 (marked E) ; and from Mr. Lupton's Numerical Tables, 

 1884 (marked L). 



I. 



Sub- 

 stance. 



II. 



Refraction, 

 p-1. 



IIL 



Density. 



d. " 



IV. 



Sp. Ref. 



JU-1 



d. 



y. 



Ratio of 

 Refraction 



to that of 

 Hydrogen. 



Remarks. 



H. 



0001387 

 14208 



00008837 

 94630 



15696 

 E 19578 



TOO 



L 18749 Another value of log. 



0. 



2706 

 43233 



14107 

 14943 



19182 

 E 28290 



1-95 



29025 



7 ■ Lupton's data of log. 

 L 27923 do. 



d 

 378134 do. 



N. 



2977 

 47378 



12393 

 09318 



24241 



E 38060 



2-14 



33170 



CL 



L 7720 



88762 



E 30909 

 49009 



24986 

 39753 



4-27 

 62992 



1 Density given by Everett. 



01. 



L 7720 



L 3-18 

 50243 



24274 



38159 





\ Density and Index according 

 J to Lupton. 



s. 



L 16290 

 1-21192 



96 XH 



98227 



19202 

 28335 



11-7 



06984 



1 Density according to Gmelin. 



p. 



L 13640 

 1-13481 



62XH 



73869 



24895 

 39612 



9-84 

 99273 



1 Density calculated from equi- 

 j valent. 



Hg. 



L 5560 

 74507 



100 XH 

 94630 



62918 



79877 



4-00 

 60299 



[ Calculated from hydrogen. 



As. 



L 11140 

 1-04689 



150 XH 

 17609 



74268 

 87080 



803 

 90479 



1 Ditto. 



J 



I propose to call the quantity /x— 1 the refraction, fi the index. 



