376 The American Geologist. juue, isoo 
forces is always signalled by the sudden appearance, in the 
previously clear and colorless field, of innumerable dark points, 
which in an incredibly short time, augment in volume, till a 
diameter of perhaps ^^oth of a millimeter is reached. It is 
then observed that the particles are spherical in outline and 
that their darkness is only an optical illusion, caused by a 
broad dilTraction-ring, for in reality they are quite transpar- 
ent. They are evenly distributed over the field, and their 
''growth" — a kind of spontaneous swelling, which can be plain- 
ly followed — is uniform and simultaneous. 
Then a startling transformation-scene is witnessed ; no kal- 
eidoscope-effect could be more marvelous. The particles 
appear to become suddenly endowed with polarity, they 
change their positions, roll about like billiard-balls in every 
direction, yet always in straight lines. For a moment all 
seems confusion, but, behold ! some invisible "floor-master" 
is asserting his authority, and in another instant we have the 
first manifestation of a symmetry, destined to culminate in 
that perfect crystalline regularity, which has excited the won- 
der of all ages. The globules, originally scattered all over the 
field, are now arranged in lines or rows, like so many strings 
of beads. Some of these rows consist of only three or four 
globules, in others we can count ten, fifteen, twenty or more, 
and it would seem as if each spherical body was surrounded 
by a delicate film or pellicle, which prevents the dissipation of 
the internal molecular forces. 
A series of rapid changes is now inaugurated, which can be 
followed only with the greatest difficulty, and of which it is 
almost impossible to give an intelligible account within the 
space here at our disposal. The globules in each line, by a 
sudden and simultaneous movement, unite and form solid 
rods, and there are grounds for believing that this solidifica- 
tion is due to the rupturing of the mysterious pellicle referred 
to. That the globules are endowed with polarity cannot for a 
moment be questioned, and — reasoning from analogy — we are 
driven to the conclusion that the north pole of one is attract- 
ed by the south pole of the other. A very close proximity would 
therefore, terminate in a sudden rush and collision. Within 
a fraction of a second after the formation of the rods (which 
are of uniform thickness, however much they may vary in 
length) we observe a general commotion among them. Each 
