A general name for the various kinds of grain which serve as food for man or other animals; thus wheat, rye, barley, maize, etc, are comprehended under the term corn. In England, however, it is usually understood to signify wheat; in America, and most parts of the world, the term implies maize, or Indian corn. Owing to adventitious or natural circumstances, corn is frequently combined with a variety of impurities, denominated smut-ball, dust-brand, pepper-brand, mildew, must, besides a portion that is decayed or partially eaten by insects; there is also frequently a mixture of gravel, earth, and different foreign substances, to a greater or less extent. To free corn from these impurities, numerous machines have been designed, but their effectiveness has proved so limited or partial, as to cause them to be very little employed; and damaged or impure corn, in consequence, possesses a value in the market far below what its intrinsic worth would be considered were there known some simple and cheap process for separating effectually the good from the bad.

An apparatus for this purpose was, however, very recently patented, which, in our opinion, is calculated to supply the desideratum in that important branch of art, the experiments already made with it having proved highly satisfactory. We make the following abstract from the specification (leaving out the references to the drawing), which embraces other mechanism and processes immediately connected with the subject under consideration.

Hebert's Patent Scouring, Washing, and Separating Machine. This apparatus "is brought into use whenever the adventitious or impure matter cannot be effectually removed by sifting or other dry operation. The grain to be washed l deposit on a floor in the upper part of a building, and contiguous to a hopper that is fixed to, and passes through a cavity in the floor. Near to this hopper l also collect a heap of very coarse sharp sand (fragments of buhr stones answer well), which has been previously well washed and sifted, so as to detain only those particles which measure from a sixteenth to a thirtieth part of an inch in diameter, and to free it from those which are either coarser or finer. Into the said hopper l then throw a charge for the scouring cylinder (situated underneath it on the next floor); the charge consisting of a mixture of the grain and coarse sand, in the proportion of about five shovelsfull of the grain to one of the sand in its wet state. The length of the scouring cylinder should be proportioned to the magnitude of the operations intended to be conducted by it; but its diameter should not be less than 30 or 36 inches, in order that the pressure of the superincumbent portion upon the lower may cause the sharp angles of the interposed coarse sand to scour off the impurities adhering to the surfaces of the grain.

A slow rotation of the cylinder for a few minutes will in general suffice to complete this part of the process; the state of which may at any time be ascertained by drawing out a sample of the grain through a try-hole, made in one of the flat ends of the cylinder, and provided with a stopper. When completed, the door in the cylinder is to be unfastened, and the mixed materials are to be discharged into a large, flat, rectangular sieve, suspended underneath it, and lying submerged in a large body of water contained in a bath. This being done, the cylinder is to be turned half way round upon its axis, so as to bring the open doorway uppermost, and opposite to the short of the hopper above, in order to its being recharged as before; after which the door is to be refastened. From this time, and at every subsequent charge until the work is completed, both the scouring cylinder and the washing and separating bath operate together, the grain in the sieve being agitated by the rotative action of the cylinder in the following manner.

On the revolving axis of the cylinder is fixed a pulley, which, by means of an endless corder chain and two guide pulleys (employed to convert the vertical into a horizontal motion), causes a fourth pulley to revolve in a horizontal plane: on the upper side of the last mentioned pulley is a plate, having an eccentric groove, in which a pin fixed to the centre of the bottom of the sieve works; this arrangement, so far, causes the sieve to perform a circular motion in the water; but the sieve is suspended from its four corners to two projecting arms or levers, fastened to two horizontal spindles (acting as their fulcra), and is, in consequence, made to incline alternately from side to side, in a constantly varying plane, during each revolution of the eccentric plate before mentioned. This compound motion produces a great agitation amongst the particles of corn and sand, causing them to be quickly and thoroughly separated from each other, and the corn to be well washed by the collision. The sand passes through the meshes of the sieve, and is deposited at the bottom of the bath; the bad corn, from its inferior specific gravity, rises to the surface of the water, whence it is floated away by a gentle current over a partition or dam in the bath, into a receptacle on the other side, whence it flows through a spout out of the machine.

The current is produced by the constant running into the bath of a small stream of water from a pipe and cock at the opposite end of the bath, and a constant level of water is preserved by its running over the dam. The purified corn alone remaining in the sieve, is now to be discharged thence; for this purpose, two levers fixed to the before - mentioned spindles, and connected by a rod (to cause them to move parallel with each other), are brought into operation; so that upon one of them being pulled, the sieve is lifted out of the water and placed in an inclined position, by which the contents are easily projected into a contiguous hopper, where the corn is allowed to drain during the washing of the succeeding charge of grain, and then it is conducted into the kiln to be dried. See Kiln.