208 
Proceedings, of the Royal Society of Edinburgh. [Sess. 
diesem Sinne wiirde man zum Bei spiel folgende Korper als zu einem mid 
demselben Typus der Molecularstructur gehorend ansehen : 
1 H 
( C1 
l C1 
(d 
(Cl 
/ Cl 
P ) H 
° 2 h H 
r )H 
° 2 ) H 
P )C1 
^ 2 h H 
P )C1 
° 2 ) Cl 
P )ci 
° 2 ) Cl 
o o 
O 
(h, 
(h, 
( 11 , 
(H, 
( Cl, 
(0, 
o 
to 
0 0.0 
( H0 o 
c H 
1 2 j H 
( HO 
p )ho 
° 2 h H 
2 j 
2 C* J 
^2 \ 
ho 2 
H ‘ r 
0 
( c 4 h 3 o 2 
) C 4 H 3 0 2 
10, 
u , 
(h 
d 
.0 , 
( ho; , 
U.S.W., U.S.W.” 
From these 
formulae 
we see that 
Butlerow 
was at that 
time still an 
adherent of the small atomic weights, or equivalents, for carbon C = 6, and 
for oxygen 0 — 8. He had thus, in this respect, remained behind Kekule, 
and, so far as carbon is concerned, behind Couper also. 
Couper set up, as I have already pointed out, two types for all carbon 
compounds, which, at the beginning of his complete paper, he formulates 
as follows (still with C = 6) : — 
?iC 2 iU 4 
?zC 2 M 4 - mM 2 .* 
Further on he adopts C = 12 for the following reasons: “There is no 
reaction found where it is known that C 2 is divided into two parts. It is 
only consequent therefore to write, with Gerhardt, C' 2 simply as C, it being 
then understood that the equivalent of carbon is (12) twelve.” 
The two types then take the forms exclusively used by Couper in his 
short paper in the Comptes rendus : — 
?<CM 4 
?<CM 4 -mM 2 
where m is less than n. 
Butlerow had difficulty in understanding these two formulae. I give 
here his criticism : “ Setzt man in dem ersten von Couper vorgeschlagenen 
Ausdruck irC 2 M 4 z.B. n = 6, so wird man C 12 H 24 haben ; die Grenze des 
Verbindungsvermogens - fur das complexe Kohlenstoffmolecul C 12 ist aber 
M 14 (allgemeiner Ausdruck = C 2n M 2n+2 ).f Will man die typische Formel 
von Couper mit den Thatsachen in Ubereinstimmung bringen, so muss 
man unter tiM 4 Affinitatseinheiten verstehen, und zu denselben die Affinitat 
des Kohlenstoff selbst (zwei Affinitatseinheiten fur jedes Molecul C 2 ), 
ausser der, die einem Molecule C 2 geliort, mitrechnen.” As already ex- 
* In the Phil. Mag. misprinted ?iC 2 M 4 - mM. See Ann. de chim. et phys. (3), liii. 480, 
line 10 from top. 
t Butlerow has obviously here in mind Kekule’s general expression C n Q.. ln ^_. 
