This cold sirup
causes a sudden though slight reduction in temperature, which may so
reduce the repulsive forces as to allow the attraction among the
molecules to prevail, resulting in the inception of crystallization. To
discover this requires the keenest observation. When beginning to form,
the crystals are too minute to show either form or size, even when
viewed through a strong magnifying glass. There is to be seen simply a
very delicate cloud. The inexperienced observer would entirely overlook
this cloud, his attention probably being directed to some curious
globular and annular objects, which I have nowhere seen explained. Very
soon after the sample from the pan is placed upon glass for observation,
the surface becomes cooled and somewhat hardened. As the cooling
proceeds below the surface, contraction ensues, and consequently a
wrinkling of the surface, causing a shimmer of the light in a very
attractive manner. This, too, is likely to attract more attention than
the delicate, thin cloud of crystals, and may be even confounded with
the reflection and refraction of light, by which alone the minute
crystals are determined. The practical operator learns to disregard all
other attractions, and to look for the cloud and its peculiarities. When
the contents of the pan have again reached the proper density, another
portion of sirup is added.
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