Chemistry and Physics. 429 
cleus, as in fig. 5, we should also have stable equilibrium (although 
less firm than before), and the result of a symmetrical develop- 
meut would be a macle such as has been represented in fig. 2, 
Whether this more complex arrangement is necessary in order to 
do not feel confident is seldom that more than three individ- 
uals can be distinguished given ; " ange ig 
development f the several individuals, and the indefiniteness of 
the lines of demarcation, resulting fr e phenomena whic 
cation of the structure. I refer » very constantly 
noticed, that the plane of the optical axes is parallel to the nearest 
hexagonal edge, as show 2. ; 
plane is parallel to the shorter axis of the ellipse! and it can easily 
be seen that if either of the individual of fig. 4 were develope 
8 
Having made the two suppositions, as above, to explain the 
phenomena of twinning, which have been long familiar and ex- 
in this paper. We may conceive that the ellipsoidal molecules, 
instead of grouping together on the same plane, become associated 
by their alternate poles, one over the other, as represented in fig. 
6. Molecules so associated, developing 6. 
e the ne of a 
, in right or left-handed 
-handed circular 
may have on the 
received theory of these phenomena as they appear in quartz, 
must be left for further analysis to discuss. : 
T pass next to consider the composition of the Culsagee vermic- 
ulite, and I give below, at (1), (2), and (3), the results of three 
mcd ses, made by myself, together with the corresponding oxygen 
ratios, 
The pulverized mineral, after it has been exfoliated gt ante is 
easily and perfectly decomposed by hydrochloric acid. 4n analy- 
