attractions and
repulsions. In virtue of these forces some poles are drawn together,
while some retreat from each other; atom is added to atom, and
molecule to molecule, not boisterously or fortuitously, but silently
and symmetrically, and in accordance with laws more rigid than those
which guide a human builder when he places his materials together.
Imagine the bricks and stones of this town of Dundee endowed with
structural power.

Imagine them attracting and repelling, and arranging themselves into
streets and houses and Kinnaird Halls--would not that be wonderful?
Hardly less wonderful is the play of force by which the molecules of
water build themselves into the sheets of ice which every winter roof
your ponds and lakes.

If I could show you the actual progress of this molecular
architecture, its beauty would delight and astonish you. A reversal
of the process of crystallisation may be actually shown. The
molecules of a piece of ice may be taken asunder before your eyes; and
from the manner in which they separate, you may to some extent infer
the manner in which they go together. When a beam is sent from our
electric lamp through a plate of glass, a portion of the beam is
intercepted, and the glass is warmed by the portion thus retained
within it. When the beam is sent through a plate of ice, a portion of
the beam is also absorbed; but instead of warming the ice, the
intercepted heat melts it internally. It is to the delicate silent
action of this beam within the ice that I now wish to direct your
attention. Upon the screen is thrown a magnified image of the slab of
ice: the light of the beam passes freely through the ice without
melting it, and enables us to form the image; but the heat is in great
part intercepted, and that heat now applies itself to the work of
internal liquefaction. Selecting certain points for attack, round
about those points the beam works silently, undoing the crystalline
architecture, and reducing to the freedom of liquidity molecules which
had been previously locked in a solid embrace. The liquefied spaces
are rendered visible by strong illumination. Observe those
six-petaled flowers breaking out over the white surface, and expanding
in size as the action of the beam continues. These flowers are
liquefied ice. Under the action of the heat the molecules of the
crystals fall asunder, so as to leave behind them these exquisite
forms. We have here a process of demolition which