SPHERICAL ELEMENTS OP CRYSTALS. 
209 
from the rest. The modifications of its erystalline form would 
probably not be alike in all directions as in the usual modifi- 
cations of the cube, but would be liable to elongation in the 
direction of its original axis. And if such a crystal were elec- 
tric, it would have but one pair of poles instead of having four 
pair, as in the crystals of boracite. 
There is, however, an hypothesis, which at least has simpli- 
city to recommend it 5 and if it be not a just representation 
of the fact, it must be allowed to bear a happy resemblance to 
truth. 
Let a mass of matter be supposed to consist of spherical Two sets of 
particles all of the same size, but of two dilferent kinds, it> t ari,, all* equal 
equal numbers, represented by black and white balls: and let 
’ ^ diHon t'tat no 
it be required, tliat in their perfect intermixture every black two a»lj icmt 
ball shall be equally distant from all surrounding white balls, 
and that all adjacent balls of the same denomination shrdl also should he 
be equidistant from each other. I say, then, that these con- tilaira'ny nether 
ditions will be fulfilled if the arrangement be cubical, and that would 
lortn a cube. 
the particles vvill be in eqnilibrio. Fig. 14 reprtsems a cube 
80 constituted of balls, alternately black and white throughout. 
The four blac k b ills are all in view. 'Ihe distances of tlieir 
centres being every way a superficial diagonal of the cut>e, they 
are equidistant, and their configuration represents a regu- 
lar tetrahedron ; and the same is the relative situation of the 
four while balls. The distanc»s of dissimilar adjacent balls 
are likewise evidently equal ; so that the concliiions of their 
union are complete, as far as appears in the small group ; and 
this is a correct representative of the entire inass that would be 
composed of equal and similar cubes. 
Since the crystalline form and electric qualities of boracite Properties of 
boiac’ite al- 
are perhaps unique, any explination ot properties so peculiar tuded to 
can hardly be expected. It may, how'ever, be remarked, 
that a possible origin of its four pair of poles may be traced 
in the structure here represented ; for it will be seen, that a 
white ball and a black one are regularly opposed to each olhc'^ 
at the extremities of each axis of the cube. 
An hypothesis of uniform intermixture of particle wit* This livpotL^ 
Voj.. XXXVl.—No. 107. Q ticle^ 
