270 Count de Bournon's Description of 
explanation of the circumstance which occurs to me, does not 
agree with the idea we have formed respecting those laws ; but 
the circumstance itself may be perfectly explained by it. It is 
founded upon a supposition that the primitive rhomboid may 
have passed, very nearly at the time the crystallization began, 
to the form determined by the combination of the two modifi- 
cations which produce the hexaedral prism, and that, in conse- 
quence of a law not yet acknowledged, the sides of the prism 
may have become, at the very moment of their formation, a 
new centre of attraction, for the regular deposition of a part of 
the crystalline molecules. This supposition, however, would 
require another, but which perhaps may be fairly considered as 
nothing more than a consequence of the former, namely, that 
the mutual attraction of the molecules situated upon these se- 
condary faces, is more strong than that which exists in the 
same way between those upon the primitive ones. This stronger 
degree of attraction between the molecules on one of the faces 
of a crystal than between those of the other, is already ad- 
mitted ; so that it may rather be considered here, as giving rise 
to an additional observation, than as affording matter for discus- 
sion. I am perfectly sensible of, and make no scruple to allow, 
every objection that may be made against this explanation, to 
arrive at which, I have been obliged to make a supposition not 
yet admitted ; but the fact itself exists, and seems naturally to 
lead to the explanation I have given. I offer it, however, merely 
as a hypothesis, which still requires the support of observation ; 
and I shall only add, that it is not the first time that the study 
of crvstals has led me to form such an idea. 
j 
With respect to the cause which, notwithstanding the above- 
mentioned mode of crystallization, would still occasion the frac- 
