The apparatus hereafter described is in general use, and was invented
by Herr Paul Grundner, of Berlin. It is particularly adapted for finely
dividing large quantities of emulsion. It consists essentially of a
wooden lid, a b, fitting upon a large stone pot, to the under side of
which two strong trapezoid pieces of wood, e d and e f, are fixed, in
the under part of which semicircular incisions are cut and held together
by two leather straps, supporting a strong, easily-removable iron
transverse bar, g h. Through the center of the lid, and turned by the
crank, m, passes the axle i, which ends under the lid in the long ring,
n.
The stiffened emulsion is then placed in the bag, o p q r, made of
fine but strong canvas, with meshes about 0.5 mm. (such as is used for
working upon with Berlin wool). The iron rod, g h, is then slipped
through the four loops at the bottom of the bag, the open end is slung
upon the ring, n, and bound tightly to it by the ribbons, r1. The loops
upon the iron bar are then pushed as close together in the middle as
possible, and the stone vessel is filled with water until o p q r is
completely covered. The crank is then turned, by which the bag is wrung,
and the emulsion squeezed through the meshes immediately into the water.
When this process is continued until the purse between n and g h feels
like a metal rod, the best part of the emulsion has been squeezed
through, and if one now take out the bag and dissolve its contents, it
will be found that the loss of emulsion is almost _nil_.
[Illustration: FIG. 2.]
It may be remarked that the whole apparatus, with the exception of the
crank, must be coated with asphalt varnish; also that the corners, r and
q, must be separated off from the purse, as shown by the dotted line, s
s s s, otherwise the emulsion would lodge there without being squeezed
through. Instead of g h a strong glass rod may be used for small
apparatus; but for large apparatus it is indispensable, as the power
that requires to be exerted would be far too great for glass.