1908-9.] Life and Chemical Work of Archibald S. Couper. 207 
of copulse. Kekule, as is well known, deduced his valency theory as 
the idea lying at the root of Gerhardt’s type theory, as he himself puts 
it, as a conscious, immediate development of Dalton’s atomic theory, 
without severing the connection with the type theory and the radical 
theory. 
Couper’s complete French paper called forth the opposition of Alexander 
Butlerow. In a paper in Liebig s Annalen, entitled “ Bemerkungen liber 
A. S. Couper’s neue chemische Theorie,” * he finds fault with Couper’s state- 
ment, “ Die Aufstellung einer Theorie ” “ ist der Zweck wissenschaftlicher 
Untersuchungen.”f This translation of Butlerow ’s is not quite accurate ; the 
French sentence is : “ L etude de la cliimie doit avoir pour but l’etablisse- 
ment de la theorie de cette science.” The English paper in the Philosophical 
Magazine , which Butlerow does not seem to have known, begins, as already 
stated, with the sentence: “The end of chemistry is its theory.” “Meiner 
Ansicht nach,” says Butlerow, “ ist die Ausbildung einer Theorie die notwen- 
dige Folge vorhergegangener Untersuchungen, der Zweck aber ist eher die 
Kenntniss der Gesetze, nach welchen chemische Metamorphosen vor sich 
gehen.” Couper would certainly not have disputed the statement that 
chemical investigations ought to teach us laws, but laws have to be 
explained, and to do that there is need of hypothesis or theory. Thus the 
ultimate aim remains still the establishment of a theory, which makes the 
laws intelligible, as Dalton’s atomic theory did for the laws of constant 
composition and of multiple proportions. 
I am inclined to think that the chief inducement for Butlerow 
to occupy himself with Couper’s new theory was the opportunity of 
stating that nine months before, that is, early in March (his paper is 
dated Kazan, 1/13 Deqember 1858), he had communicated similar theo- 
retical views to members of the Chemical Society of Paris, although 
he had not then printed them. He repeats what he then said as 
follows: — “Wenn man unter den Badicalen nur Reste versteht, welche 
ihre Constitution in einer gewissen Anzahl der Reactionem beibehalten, 
so konnen mit demselben Rechte, wie die organischen Gruppen und 
Elemente, auch die Reste 
H0 0 vein Ty puSrj- i 0 2 f, NH 0 vom Types H N 
j " H j 
als Radicale betrachtet werden, und man konnte annehmen, dass sie ein 
Atom eines Elementes in verschiedenen Gruppen substituiren konnen. In 
* cx. 51-G6 (Heft 1, issued 16tli April 1859). 
t “Wie es Laurent annahm.” 
