The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1902-04-20
GROWTH OF A CRYSTAL
cfYSTERY OF THE LABORATORY
SOLVED BY PHOTOGRAPHY.
Unique Experiments Made by n Har-
ward Professor, Who Combined
Microscope with Camera.

CAMBRIDGE, Mass, April Bone OF
the latest applications Of photography to
the solution of the problems Of science has
been made by Prof. Theodore William
Richards. of the department of chemistry
at Harvard. IN the study Of the formation
and growth OF crystals. The experiments
have led to definite discoveries toward
which observers have been working for
nearly twO-thirds of a century. Previous
Investigations had been made with the as
sistance Of the microscope alone and the
record OF what they developed was the
work OF human eyesight. human memory
and transcription by human hands-aH OF
which are obviously liable TO unconscious
error 0r misstatement. BY adding the cam
era TO the microscope Professor Richards.
assisted by Mr.. z. II. Archibald. a graduate
student, has succeeded not only in securing
a more accurate. permanent and convincing
record of the growth Of several varieties Of
crystals. but in obtaining many details OF
this development. which had previously es-
capped merely visual observation.
The study OF the birth Of crystals has in
terested chemists since 1899. Whether mat
ter in solution took the form Of liquid
globules just before capitalization began.
or whether the little particles gathered in
clusters Immediately the temperature and
degree Of saturation TO which they were
subjected reached the proper point, has
been an unanswered question. the gem
orally accepted opinion, however, inclining
20 the former theory. Professor Richards
Investigations, although he says that they
should merely form the basis of further
study. go to show that the formation of
crystals from a solution is accomplished
with no intervening process-that is, that
the second theory is correct. So rapid is
the growth Of crystals that, though the In
tervaIs between Professor Richards's expos
ures were only n fifth Of a second. many
changes occur even In so short a time as
this. and it may be argued. therefore, that
at some time between the blank plate with
which each series of photographs begins and
the next plate with it's impression OF the
tiny particle which is to grow into the de-
veIoped crystal. the liquid globuie may have
formed and passed into another state. On
the other hand, no evidence OF this was
found on any OF the hundreds of plates
taken; and it seems hardly likely that this
could have been the case IL the "globule
theory" were correct.
CRYSTAL FORMATION.
4 crystal OF potassium iodiGe-to name
one Of the substances on which Professor
Richards has been at w~ork-.akes only a
few seconds to grow from the first tiny
point 20 appreciable size. The point begins
by spreading into a thin plate, which
thickens by degrees as it increases In size.
and so rapid is its development that even
with the short exposure that Professor
Richards allowed the images were fire.
quently blurred. a comparison Of successive
photographs shows that the growth OF a
crystal during the first second Of its life is
very much greater than later on. Ere
quently the little structure increases less
than half as rapidly in the second second
as In the first. and much more slowly after
wards. There does not seem 70 be any
exact law in the matter. but there is a
certain regularity apparent in all the photo
graphs. though this regularity is so easily
affected by varying conditions Of tempera-
ture and evaporation as 10 be very difficult
OF exact calculation. It Is particularly in
teresting that a crystal seems generally
in its earlier stages TO grow in the same
proportion in all directions. After a while
81 becomes broader in proportion TO its
length. but by this time neighborinS crys-
tails have grown so much as to approach IL
and so alter the conditions. It is this Quick
growth az first which doubtless explains
the suddenness Of its appearance 20 the eve
Of the observer; at the same time the fact
places a serious bar in the way Of more
precise study Of the beginning OF the phe-
nomenon.
Professor Richards's task was as difficult
as II was interesting. His microscope had
20 be OF great power and the action OF the
camera shutter as rapid as il could be
made. Then. in order that the period Of
1900 v,F~I~ n. sHr H~f.Fo-. ~o.-fIt- -
at the same time a clear negative obtained.
a very intense degree OF illumination was
necessary. since the greater the efficiency
OF the combination OF microscope and cam
era the more brilliant the light must be-a
difficulty which was complicated by the
further fact that most crystals are so
transparent as 10 absorb but little light
At the best. SO that 1t is hard to obtain a