Geological Society. 307 
Afterwards in Piedmont, “on removing some indistinct crystals 
of alalite and garnet, which he had discovered on breaking an 
amorphous mass of those substances, and on taking the proper 
precautions, consisting in throwing some loose earth and stones 
against the surface from which the crystals had been removed ; 
after the lapse of six years, M. M. had the satisfaction of gather- 
a second and a third crop of new beautiful crystals, formed du- 
ring that period, some of which were sent to the public institu- 
tions at Paris. 
Having transported some of the shapeless mass of alalile, 
garnet, green idocrase, pyroxene, and amorphous pyrites; and 
formed with them an artificial mountain, which was placed on 
the chimney-piece in his room; after many days and weeks of 
anxiety, he had at last the pleasure of seeing crystals of all these 
substances emerge from this heterogeneous mixture.  “ The 
first,”’ says the author, “ which I had the satisfaction of seeing 
on my artificial mountain, were small prisms of pyroxene; next 
came the summits of crystals of alalite, then planes of garnet, 
after which those of zdocrase and peridot followed in succes- 
sion.” 
To produce new crops of crystal from cabinet specimens, was 
the next attempt. In July 1814 three specimens of idocrase, 
properly examined and described, were delivered to him from 
the School of Mines, and in November were submitted to the 
crystallizing process. In April 1815 new crystals were found 
on the surface of each of the specimens. 
From a number of similar facts M. Methuon conceives that 
the natural process of crystallization originally begins im a par- 
tial decomposition of the surface of a crystallizable fossil; that 
from certain spots of this surface, where it has first begun, the 
decomposition proceeds in straight and narrow lines to other 
similar spots which in their turn send forth similar lines, some- 
times parallel to the former, at other times crossing each other ; 
thus dividing, or, more commonly speaking, carving or engraving 
the surface of the fossil into several compartments, which be- 
come, by a continuance of the process of decomposition, as many 
distinct pieces, constituting the body of the crystal in its rough 
state; and lastly, that during this process the substances of a 
different nature, contained in the mineral, separate, and arrange 
themselves, in one or more parts of the same compartment, the 
fossil mass continuing to be solid and hard, but fragile and easy to 
be broken;’’ the author having often broken, between his fingers, 
some which had before withstood the strongest percussions. 
M. Methuon maintains that he has proved ; ‘¢ 1st, That cry- 
stals begin to form at their summit, edges, and solid angles. 
U2 2dly, 
