CHEMISTRY AND PHYSICS. 45 
the molecule depends upon the arrangement of its constituent atoms, and that in 
turn upon their constitution and nature and the forces at play upon them; so we 
must understand the atom in order to understand the visible crystal. When we 
shall know all this, and the driving force which impels atoms and molecules to 
their manifest results as symmetrical structures and organisms, who will say that 
we will not understand not only what light is, and electricity, but also what 
gravity is, and life? Our present fund of knowledge, great as it is, will be con- 
sidered small indeed as compared with what it shall be then. 
’ As a few possible hints in the direction of such knowledge, I desire to direct 
your attention to some concretionary forms which I shall use by way of illustra- 
tion. There is an undoubted unity in the universe, one pervading principle. In- 
deed, the word ‘‘universe’’ means that very thing: all ‘‘turned to one.’’ All 
facts, then, rightly comprehended, must lead toward the solution of this great 
problem which we have suggested. 
We will first consider the structure of the ‘‘ pillow-witch.”’ A ‘‘pillow-witch”’ 
is an aggregation of feathers formed sometimes in pillows by the feathers accu- 
mulating about a nucleus or center. A few hairs will first work ‘their way into 
the pillow; these will become more or less tangled under the continual move- 
ment of the contents of the pillow when in use. The feathers will always be 
worked in the same direction; that is, with the shaft forward. The tangled hair 
will arrest a few, others will be crowded in between these, always being forced 
into the bunch with the shaft forward. Because of the curved structure of each 
individual feather, the resulting concretion will be symmetrical in form, and 
every constituent feather will point to the nucleus. 
Very similar in structure are the hair balls taken occasionally from the stom- 
achs of cattle, and resulting from the accumulation of hair swallowed in the act 
of licking other cattle. If we cut into one of these balls we will find the short, 
curved hairs arranged approximately parallel and pointed to a nucleus, just as 
in the case of the feathers in the pillow-witch. A few tangled ones formed a 
nucleus at first, then under the churning action of the stomach others were 
driven end first into this mass. This is indicated by their parallel arrangement. 
After the shedding season is over, and hair is no longer swallowed in consider- 
able quantities, a slimy deposit of salts begins to form over the outside, which 
hardening renders the ball impervious to the entry of other hairs, thus determin- 
ing its size and structure. 
Now, may not crystalline aggregates such as calcareous, pyrite, and flint nod- 
ules, and even crystals themselves, result by an analogous process? There are 
certain facts which indicate such to be the case. Too violent an agitation of the 
pillow will cause the outer layers of feathers to break away from the ‘‘ witch,’’ 
thus tending to make balls of only small size. Likewise in the formation of 
crystals from solutions, the crystals will always be small when obtained from hot 
solutions; that is, from solutions where the molecules are in violent agitation 
because of the high temperature. Large crystals are obtained only from cold 
solutions, where the agitation is relatively mild. In their formation we find the 
molecules are pressed toward centers or nuclei, just as the feathers were pressed 
toward the ‘‘witch”’ nucleus, by the motion of the surrounding matter. 
The ‘‘ pillow-witch”’ required a nucleus of tangled hair or broken feathers or 
other foreign material. It is a well-known fact that crystals also form more 
readily if dust or other solid particles be in the solution. Indeed, with certain 
degrees of concentration they fail to form in the absence of foreign solid particles, 
but the moment these are added crystallization begins. When it is desired to 
obtain large crystals of any salt the solution is concentrated to the right degree, a 
