414 7 Scientific Intelligence. 
property U varies with the increase of « and 6; they express - a 
of the variation and may therefore be considered as constant, cond 
and higher differential coeffivients consequently vanish and we so 
dU , dU 
ye 15 ata t (6,) 
i dU , dU 
and if k be a constant = de tar (7.) 
DasU  ~UsSka (8.) 
from which it follows that the difference D of the properties U, and U of 
two homologous bodies is proportional to the difference of their chemical 
constitution. 
The complete law of the variatiom of the properties of homologous 
bodies is given by equation (5) and if we $2 P for the sum of the 
terms containing higher powers of 4 we shall 
Ded ; vUara4s, 
from which it follows that mctes 2 speaking the difference of properties is 
not directly proportional to ifference of chemical constitution but is 
more nearly proportional a atallee the influence of the term S. 
explains small deviations from the exact law in the case of boiling points, 
The factor & will in if eee et ber identical in the case of different 
homologous series, in the se 
the property V is a function of the molecular states a, 6, ¢ and the num- 
bers a, 8, 7 of the elements C, 
V=4(a, «3 = B; ¢,7) 
the function ® being different from F es st molecular force e differs 
from the molecular force c. Hence we shall hav 
D’=V,—V=4 ; av at t +8’ 
or (10) Di=V ,—V=hI+9/ 
so that in this series also the difference in properties will be nearly ae 
portional to the difference in constitution but wil! not be 1 ane tical w) 
the difference in the case of the first series, the modulus & 
ent from & This explains the variation in uniformity ex 
Kopp’s laws of serial differences. The autho il se coon oe the 
investigations in the same direction. The nt, as it seems — of 
reviewer, to a somewhat elaborate though aay > mnathetn tical gine 4s 
that which can be shown to be necessarily true by much simpler reaso! 
I Fir prakt, Chemie, \xxxiii, p. 494. seni 
7. On the Conversion of Monobromid of geste into Acety car 
Sawrre ified that the bromid C,H,Br.Br, w mposed ona ; 
alcoholic eo of potash, gives bibromid of abylens: ies he . te 
y a small quantity of other pnecage- stan 
evolved during the reaction are conducted into an ee solu 
Of of copper, a dark red flocky Bor is produced whi 
tinue his 
