206 
SPHERICAL ELEMENTS OF CRYSTALS. 
Union of 
other solids 
allii il to tile 
sphere. 
(hystallojrra- 
pliic solids 
formed by ob- 
late spheroids 
'I'he obtuse 
rlioinboid. 
this texture composes a regular tetrahedren, which is a very 
usual figure of the crystals of alum. And there is no one 
figure into which alum is observed to be crystallized, but 
may, by this texture of globules, be imitated, and by no other.” 
It docs not appear in what manner this most ingenious phi- 
losopher thought of applying this doctrine to the formation of 
quartz crystal, of vitriol, of salt-petrc, &c. which he names. 
This remains among the many hints which the peculiar jea- 
lou'^y of his teiiiper left unintelligible at the lime they were 
written, and which, notwithstanding his indefatigable industry, 
were subsequently lost to the public, for want of being fully 
developed. 
We have seen, that by due application of spheres to each 
other, all the most simple forms of one species of crystal will 
be produced, and it is needless to pursue any other modifica- 
tions of the same form, which must result from a series of de- 
crements produced according to known laws. 
Since, then, the simplest arrangement of the most simple 
solid that can be imagined, 'affords so complete a solution of one 
of the most difficult questions in crystallography, we are natu- 
rally led to inquire what forms w-ould probably occur from the 
union of other solids most nearly allied to the sphere. And 
it will appear that by the supposition of elementary particles 
that are spheroidical, we may frame conjectures as to the ori- 
gin of other angular solids well known to crystallographers. 
The Oituse Rhomboid. 
If we suppose the axis of our elementary spheroid to be it* 
shortest dimension, a class of solids will be formed which are 
numerous in crystallography. It has been remarked above, 
that by the natural grouping of spherical particles, fig. lO, 
one resulting solid is an acute rhomboid, similar to that of 
fig. 2, having certain determinate angles, and its greatest 
dimension in the direction of its axis. Now, if other particles 
having the same relative arrangement be supposed to have the 
form of oblate spheroids, the resulting solid, fig. 12, will still 
b« 
