484 



Intelligence and Miscellaneous Articles, 



therefore, under the supposition that 



M = A + 



I gave the formulae 



M=. 



B 

 X 2 ' 



N= 



B 



d ' d l> 



in which the first denotes the refractive, and the latter the dispersive 

 power. 



A knowledge of this function renders it possible to take into ac- 

 count the dependence of the propagation of light on chemical decom- 

 position. It was found that, calling the product of the atomic weight 

 P with m (that is, Pm = M) the refractive equivalent, M of a com- 

 pound is the sum of the simple or multiple M of the constituents in 

 the form 



M(a + b + c . . . .)=M(a)+M(6) + M(c). . . ., 



in which the refractive equivalents M for the different states of ag- 

 gregation of a substance are in simple multiple relations. The 

 application of this law, especially to binary compounds, rendered it 

 possible to deduce from the observations at hand (which the author 

 by his own observations partly increased and partly supplemented) 

 the refractive equivalent of a great number of elements, and to find 

 a number which quantitatively establishes the optical character of a 

 compound, just as the atomic weights do the chemical character. 



Assuming the atomic weights (H=l, 0=16), the following 

 values of the refractive equivalents of thirty-three elements were 

 found for their (g) gaseous or vaporous, (s) solid or liquid, or (m) 

 metallic condition, the refractive equivalent of hydrogen being taken 

 at unity. 



Aluminium. . . . 



s 



5-85 



Mercury 



s 



18-99 



Antimony 



m 



76-35 



„ ...... 



m 



99-3/ 



Arsenic 



.. g 



4-09 



Nitrogen .... 



s 



2-10 



>> • 



s 



12-39 



Magnesium • , 



s 



7*38 



Barium 



s 



10-98 



Oxygen 



•• 9 



1-98 



Bismuth 



m 



81-62 



Phosphorus . . 



•• 9 



4-85 



Lead 



m 



89-50 





s 



18-88 



Boron 



s 



6-00 



Potassium .... 



s 



4-77 



Bromine 



s 



10-86 



Sodium 



s 



3-71 



Carbon 



s 



5-06 



Sulphur 



•• 9 



3-96 



Calcium 



s 



7-74 





.. s 



16-13 



Cadmium 



s 



11-72 



Selenium .... 



m 



3011 



Chlorine 



•• 9 



5-56 



Silver 



m 



34-09 



Copper 



m 



18-01 



Silicium 



s 



8-81 



Iron 



. . TYl 



33-89 

 1-00 (?) 



,, ...... 



Strontium .... 



m 

 s 



32-77 



Fluorine 



S 



8-50 



Hydrogen 



•-• 9 



TOO 



Titanium .... 



s 



31-98 



Iodine. ....... 



s 



19-03 

 3-25 

 7-95 



Zinc 



s 

 m 

 s 



7S7 



Lithium 



s 

 •• 9 



21-75 



Mercury 



Tin 



19-88 



The numbers thus obtained render it possible to establish several 

 comparisons as to the similarity of the optical and chemical character 

 of the elements. — Poggendorff's Annalen, January 1866. 



m. 13, 



