Barbour County index. [volume] (Medicine Lodge, Kan.) 1880-current, 1883-08-17

Thus, at the large end of this tube arp
placed two semi-circular quartz plates
of equal thickness, one possessing the
right and the other the inverse power
of rotation. At the lower part of the
instrument are two wedge-shaped
quartz plates, one movable and the
other fixed, but both of the right polar
izing description, while to q fixed plate
above is attached scale that gives the
final test of the operation. Looking
through these plates at strong com
densed gas light at the end of the In
strument before their thickness is adj
justed, it will be seen that the two
quartz-plates of diverse polarizing pow.
ers have the effect of dividing the ray oi
light into two distinct colors, rose and
blue, the disk showing hair-line in its
perpendicular diameter. Now, by turn
ing the thumb-screw beneath the wedge
shaped plates, their combined thickness
is increased or diminished until they
exactly equal that of the plates at the
rear of the instrument, where it will be
observed that the two colors have
blended into one uniform tint. The
scale attached to the movements of the
wedge-shaped plate is divided into one
hundred equal parts, and when the OBJ
servation tube, filed with distilled water,
is placed in the instrument between the
two ends, and the color is uniform, the
scale registers zero.
But if a solution of pure refined sugar
is placed in the tube possessing the
property of right polarization, the two
distinct colors, each in its semi-disk,
will be discovered. Then, by turning
the thumb-screws until the combined
thickness of the forward plates is dimin-
ished sufficiently to show the polarizing
power of the solution to compensate for
this disturbed thickness, the uniform
blending of the colors is again obtained
and the scale is found to register one
hundred per cent. Now, if sugar of
unknown percentage in saccharine mat
ter is taken in the same quantity and
subjected to the same tests in order to
obtain a uniform blending, it will be
necessary to adjust the forward plates,
in order that the polarizing power of
the sugar solution shall compensate for
the quartz. and when this point is OBJ
tanned the exact percentage will be
shown in the movable scale. The chem
ical preparation of each solution, so as
W hSuO uhalOiihlay III tcStllAks iSNNcIy
ingenious, but the description would De
of little practical value to the general
reader. Suffice it to say that two tests
are made of every sample, and the low
er one forms the basis of valuation.
The general use of this instrument in
the assay of sugars may prevent the
fraudulent entries that were frequent
when the Dutch color formed the stand.
ard of values, as it was found possible
to degrade the color to lower point
without impairing the quality of the
sugar. In this description two facts
were impressed upon the mind-the re-
splendent beauty under the microscope
of mite of crystalized sugar or rock
candy, that is reckoned at one hundred
per cent, and the test of the polariscope
in finding color-blindness in those who
seek to blend the colors to uniform
tint, for by actual experience it was
found to be ten times more difficult
than in adjusting the focus of an astre-
nomical telescope. - San francisco
Chronicle -