In some the comb holders are hinged in the corners of the basket, and have an angular motion of ninety degrees.  Decreasing the speed is sufficient to swing these.  The other side is then emptied by revolving in the opposite direction.  In one case each holder has a spindle of its own, connected with the main spindle by gearing and, to present opposite side, turns through 180 deg..  The usual number of sides and hence of comb holders is four, but eight have been used.  There are minor differences in details of construction, looking to the most convenient removal and insertion of comb, the reception of the extracted honey in cups, buckets, etc., and the best method of giving rapid rotation, which cannot be touched upon.  The product of the operation is white and opaque, but upon heating regains its golden color and transparency.

STARCH.—­A centrifugal to separate starch from triturated grain, carried in suspension in water, is as follows. (Pat. 273,127—­Mueller & Decastro.) The starch water is led to the bottom of a basket, and, as starch is heavier than the gluten with which it is mixed, the former will be immediately compacted against the periphery of the basket, lodging first in the lower corner, the starch and gluten forming two distinct strata.  A tube with a cutting edge enters the compacted mass so deeply as to peel off the gluten and part of the starch, which is carried through the tube to another compartment of the basket, just above, where the same operation is performed, and so on.  There may be only one compartment, the tube carrying the gluten directly out of the machine.  These machines are continuous working, and hence some way must be devised to carry the water off.  The inner surface of the water is, as we have seen, a cylinder.  When the diameter of this cylinder becomes too small, overflow must be allowed.  One plan is to have an overflow opening made in the bottom of the basket in such a way that as the starch wall thickens, the opening recedes toward the center.  The starch wall is either lifted out in cakes or put again in suspension by spraying water on it and conducting the mixture off.

A centrifugal (Pat. 74,021) to separate liquids from paints depends on building a wall of paint on the sides of the basket and carrying the liquids off at the center.

A centrifugal (Pat. 310,469) for assorting wood pulp, paper pulp, etc., works by massing the constituents in two or three cylindrical strata, and after action severing and removing these separately.

BREWING.—­In brewing, centrifugals are quite useful.  After the wort has been boiled with hops, albuminous matters are precipitated by the tannic acid, which must be extracted.  Besides these the mixture frequently contains husk, fiber, and gluten.  The machine (Pat. 315,876), although quite unique in construction, has the same principle of working as a sugar centrifugal, and need not be described.  There is one point, however, which might be noticed—­that air is introduced at about the same point as the material, and has an oxidizing and refrigerating effect.