Chemistry und Physics. 67 
densities and the refractive indices were determined at 20°, the 
former being referred to water at 4° and to a vacuum, the value 
being indicated by d* and carried to four décimal places. The 
indices for obtaining the suibaaslannoetiowe t A, were those o 
q and H andolt’s investigations, the same molecular re- 
fraction was cbedied for all isomeric bodies; thus showing that 
only the number of the atoms and not their arrangement influenced 
all their compounds; and by comparing different bodies together 
the atomic refraction * for carbon was given as 4°86, of hydrogen 
as 1:29 and of oxygen as 2°90. Hence the molecular refraction of 
e bond, e 
upon the pbaconsiasicik of light chin those pooh bound. If I 
the calculated refraction-equivalent of an 5 we oerai hy: 
carbon, @ the influence of a double union, and « the of 
=e of removed hydrogen atoms, the formula for a body. repre- 
ented by ( on+2) 2 
would be p(“5+)=R ataxa. If y represent the number of pairs 
of hydrogen atoms removed to form a closed chain, and hence 
Without influence optically, the formula becomes P > = 
Ri+(a —y)a. Forexample, in hexylene, one pair of carbon atoms 
is doubly united. Hence we have (C,H,,.)—H,, and the formula 
is PAS ~)=Ru+a. In diallyl, we have (O.N,,,,)—2H, and the 
d 
formula is P a 
=)=Ra+2a. In benzene, we have (C,H,,,.)— 
4H,; but a closed chain exists, with only three double unions; 
therefore z—y=4—1=3 and the formula becomes P — a 
R,+3a. Experiment has fully confirmed — P icacen which 
have been extended to chlorine, bromine and nitrogen which 
have atomic refractions of 9°53, 14: 75, and 5°35 dedcnctraly. The 
author thus states it:—The molecular refraction of those bodies 
from the sum of the atoms, and the excess is 
proportional to the number of such dual unions, being two units 
ee 
for one and 2z units for z double unions. MP we = 
R,+2z. But this is aa equivalent to saying that the atomic 
refraction of carbon gher when doubly combined. This con- 
cedes the variability of mest refraction, which appears to be the 
Se not only with carbon and oxygen, but also with all poly- 
tert elements. The atomic refraction of singly united carbon 
8 4°86 as above; but that of doubly united carbon is 5°86.— Ber, 
Berl Chem. Ges., xii, 2135, Nov., 1879. G. ¥. B 
