38 Count de Bournon’s Description of a 
bination, in different proportions, of the primitive molecules of 
two or more different substances. The difference existing be- 
tween mineral bodies, consequently depends upon the following 
circumstances; first, upon the nature of the primitive molecules, 
by the combination of which they are produced ; secondly, upon 
the proportion in which those molecules are combined together. 
At the instant the new or secondary molecules are formed, 
if they happen to be at a proper distance from each other, and 
in a fluid which permits them to move freely, they become 
subject to, and are forced to obey, the second species of attrac- 
tion, namely, the attraction of aggregation, which unites them 
into one or several masses, perfectly homogeneous in all their 
parts. 
But the attraction of aggregation seems to be susceptible of 
various modifications, which alter its manner of acting upon the 
constituent molecules. Of these modifications there are two 
principal ones ; the first of which may, I think, be distinguished 
by the name of crystalline attraction of aggregation ; the second 
may be called simple attraction of aggregation. 
The crystalline attraction of aggregation always takes place 
between similar molecules ; which molecules are simple or pri- 
mitive, in those bodies which are considered as simple or 
primitive, (and which in fact are so,) and they are compound 
in other bodies. This kind of attraction, in its action upon the 
molecules under its influence, is either regular, irregular, or 
amorphous. 
In the regular crystalline attraction of aggregation, the mo- 
lecules arrange themselves in such a way as to give rise to solid 
bodies, which are either constantly of the same form, or are 
subject to certain laws of variation ; these variations, however. 
