1887.] 



Dispersion Equivalents. 



407 



thylene was found to be 3*65, and in iodoform in solution it seems 

 to be about the same ; while in the ordinary iodides of the compound 

 radicles it is much less. 



Nitrogen. — Mtrogen appears to have a lower value in nitriles, 

 cyanides, and sulphocyanides than in organic bases : but the figures 

 obtained so far, for each condition of nitrogen, are not accordant. 

 The lower value, however, probably does not exceed O'lO. The 

 values of N"0 2 in the fatty acid series, as deduced from substitution 

 products of the alcohols, glycerine, mannite, &c, are, however, fairly 

 accordant, giving about 0'82. 



Sulphur. — For the determination of sulphur, we have the excellent 

 observations of Wiedemann,* and JNasini ;f the first on sulphur 

 substitution products of carbonic ethers ; the second on many organic 

 compounds. There exist also two or three observations of my own. 

 It appears that the value of sulphur in mercaptans, sulphocyanides, 

 and sulphides of ethyl, butyl, amyl, and allyl, is about 1*21 ; answer- 

 ing to the refraction equivalent of 14*0. 



But in bisulphide of carbon, where the refraction equivalent of 

 sulphur is 16 - 0, the dispersion equivalent is 261 : and this is about 

 the value which the element appears to have in the isosulphocyanides, 

 while the element itself dissolved in bisulphide of carbon, gives 1*20 

 for the dispersion F— A, which is equivalent to fully 2*5. 



These results are collected together in the following table. The 

 dispersion equivalents here given must however not be taken for 

 anything more than approximate. 



Substance. 



Atomic 

 Weight. 



Refraction 

 Equivalent A. 



Dispersion 

 Equivalent H — A. 







31 



18-3 



3-0 





32 



16-0 



2-6 



„ single 





>> 



14 -0 



1-2 





1 



1-3 



0-04 







12 



5-0 



0-26 







» 



6-1? 



0-51 









6 1 



0-66 





16 



3-4 



0-18 



„ _ single 





>> 



2-8 



o-io 







355 



9-9 



0-50 







80 



15-3 



1-22 







127 



24-5 



3 65 







14 



4-1 



o-io 



CH 2 





14 



7*6 



0-34 



N0 2 





46 



11 -8 



0-82 



* ' Journ. Prakt. Chem.,' vol. 114, 1873, p. 453. 

 f ' Gazz. Chim. Ital.' vol. 13, p. 296. 



