294 Jean-Baptiste-André Dumas. 
in them in equal numbers. An immediate consequence of 
this mode of looking at the question has already been the sub- 
ject of a learned discussion on the part of Ampére,”—and 
Avogadro as the author subsequently adds,—‘“ to which, how- 
ever, chemists, with the exception perhaps of M. Gay-Lussac, 
appear to have given as yet but little attention. It consists in 
the necessity of considering the molecules of the simplest gases 
as capable of a further division,—a division occurring in the 
moment of combination, and varying with the nature of the 
compound.” 
Here, it is obvious, are the very conceptions which form the 
basis of our modern chemical philosophy; and at first we are 
surprised that they did not lead Dumas at once to the full reali- 
zation of the consequences which the doctrine of equal molecu- 
lar volumes involves in the interpretation of the constitution of 
chemical compounds, and to the clear distinction between “ the 
known by Dumas’s name. The other was a radical change i0 
the formula of the silicates. On the authority of Berzelius, 
who based his opinion chiefly on the analogy between the sili- 
eates and the sulphates, the formula SiO, bad been ac 
cepted as representing the constitution of silica. But from the 
density of both the chloride and the fluoride of silicon Dumas 
concluded that the formula was SiO,, a conclusion which is noW 
seen to be in complete harmony with the scheme of allied com- 
pounds. To Berzelius, however, the new views appear 
wholly out of harmony with the system of chemistry which he 
had so greatly assisted in developing, and he opposed them 
with the whole weight of his powerful influence, and so far 
succeeded as to prevent their general adoption for many yeals- 
