188 Dr. Caruelley on the Influence of Atomic Arrangement 



Structure. 



Molecular 



refraction- 

 For- equivalent. ; Differ- 

 mula. 



Found 



! Calcu- 

 lated. 



Propyl alcohol. CH 3 .CH 2 .CH 2 .OH C 3 H,0 2800 



Amylene CH 3 .CH 2 .CH 2 .CH=CH 2 ; C 6 H 10 3921) 



Diallj-1 CH 2 =CH.CH 2 .CH 2 .CH=CH.Jc 6 H u , 45-99 



Valerylene CH 2 =CH.CH,CH=CH 2 C 5 H, 3865 



r HC— CH -» I 



Benzene 



Toluene . 



HC 

 HC- 



CH 

 -CH 



Mesitylene . 



HC 

 \ 

 CH 



CH :J 

 \ 

 C— C 



c 



C-CH, 



eg 



CH 3 



C-CH. t 

 C=CH 3 



C R H B 4216 



C T H, 5006 



C 9 H ]2 



65-22 



27-61 0-39 



37-20 209 



4206 3-93 



34-62 4-03 



36-90 5-26 



44-34 5-72 



Xo. of double 

 linfcings X 2 

 = difference. 



[No double 

 |_ linkings. 

 =1X2=2 



=2x2=4 



=2x2=4 



:3X2 = 6 



=3X2=( 



59-22 600 =3x2=( 



lents of compounds, and also what great service the knowledge 

 of refraction-equivalents is capable of rendering in the deter- 

 mination of the constitution of compounds. 



VI. Influence of Atomic Arrangement on 



Fluorescence. 



Till within a few years ago, the number of bodies known 

 which possessed fluorescing properties was very small. And 

 it is only with the advance of the manufacture of coal-tar 

 colours, and the investigations to which this advance has given 

 rise, that a large number of fluorescing compounds has become 

 known to us ; so that the phenomenon of fluorescence has 

 nowadays ceased to be a rarity. Up to the present, however, 

 but little has been done in tracing any connexion between this 

 property and the chemical constitution of the bodies exhibiting 

 it. There can nevertheless be no doubt that it is dependent 

 on a certain grouping of atoms — -just as the tinctorial proper- 

 ties are dependent on special atomic groupings, as pointed out 

 by O. X. Witt, to which I shall shortly refer. 



Quite recently, Liebermann {Ber. xiii. p. 913) has made 



