Biography of Berzelius. 181 
Much later, Berzelius assumed the existence of another force, 
although only as regarded some special chemical changes—the 
catalytic force. The evolution of light and heat, according to 
the electro-chemical theory, could only result from the combina- 
tion of bodies opposite in their characters; but when they occur 
in the decomposition of bodies, or when compounds are decom- 
posed and new ones formed, while at the same time the body 
whose presence causes this change takes no part in it, Berzelius 
ascribed this effect to the force of catalysis. 
uch has been brought forward in opposition to the assump- 
which stand isolated, for which no suitable analogues can be 
found, and which appear as it were wonderful, should provision- 
ally be ascribed to a peculiar cause or force, so as openly to ad- 
mit, that in the present state of the science it is more appropriate 
not to explain a chemical process at all, than to do so in a forced 
and fastidious manner. With the advance of the science, the 
number of phenomena belonging to such categories will always 
become smaller. 
After Berzelius had labored uninterruptedly during a space of 
ten years in the investigation of the atomic weights, of the ele- 
of organic bodies had been instituted a few years previous to the 
appearance of this paper, by Thenard and Gay-Lussac, 1n 1811. 
Nevertheless, they contented themselves with drawing no other 
inference from their results than that a vegetable substan 
