Under the article Corn is described an apparatus for washing and separating the impurities with which grain is always to a greater or less extent contaminated; and, as a necessary concomitant to that machine, a kiln was devised for drying the washed grain; but as this kiln is equally applicable to the drying of malt, seeds, and all other matters of a similar kind and form, and by a mode that is as novel as it is efficacious, we give a description of it in this place. In the engraving on the next page, Fig. 1 exhibits a longitudinal section of the apparatus, and Fig. 2 a transverse section of a long air-trough, shown at e in Fig. 1. At a is shown one of a series of five or six common iron gas tubes, placed side by side, and curved in the form represented to constitute a fire-place, the space between the tubes serving for the admission of air for combustion, which enters through the ash-pit door b at the side, provided with an air regulator: the fire-place is inclosed in front at c by a common door and frame.
The heated air, and other products of combustion from the fuel, pass along the flue d to the funnel or chimney; the bottom and two sides of the flue d are of brick, but the top is of iron, being formed of the bottom of a long shallow iron box or air-trough e; this box has no cover but one of extremely open woved canvas, which forms a part of an endless cloth or band fff, that is continually made to travel lengthwise over the whole area of the said trough; the edges of the cloth gliding between grooves and over tie-rods, (shown in the cross section, Fig. 2, where the dotted line f indicates the endless cloth,) that prevent the cloth from sagging. This cloth is made to travel by the revolution of three rollers or drums g, h, i, to either of which the moving power may be applied. The cloth is kept distended by a self-acting tightening roller, which is screwed against the hopper k; this hopper receives the grain to be dried, and is provided with a shoe at l, adapted to deliver a thin and uniform stratum of grain upon the endless cloth, whilst the same is made to pass under it, and over the trough. Another endless band m m, of a similar fabric to the other, passes round the drums h i only, and is likewise provided with a self-acting tightening roller, fixable to any convenient object.
The lower ends of the six tubes a of the fire-place before mentioned have an open communication with a rotative blower o, by means of a broad channel pp; and the upper ends of the tubes a also open into another broad channel q which conducts the air into the long air-trough e. The operation of this machine is as follows. A slow rotation, derived from any first mover is to be given to either of the drums g, h, i, which will cause the endless clothfto gide gradually over the top of the air-trough e; at the same time the blower o has been put into action (by connexion with the first mover) at a high velocity, so as to produce a rapid current of air, which derives an increase of temperature on passing under the heated metallic bottom of the ash-pit; hence proceeding through the tubes a it acquires considerable heat, which is subsequently moderated by an extensive diffusion in the air-trough e, before it passes through the meshes of the endless cloth h above, carrying with it the moisture from the grain deposited thereon.
The course taken by the endless cloth is shown by arrows in the figure; upon its arriving at the drum h, the other endless cloth m m comes in contact with the grain on the cloth f, and upon both the cloths passing round the said drum h, the corn becomes inclosed between the two cloths, and is thus carried up an inclined plane over the drum i, where the cloths separate, and discharge the grain back again into the hopper k, to undergo a repetition of the operation, should it not be perfectly dry. But when the grain is thoroughly dried, instead of allowing it to fall back into the hopper, a shoot, or the band of a creeper, (not shown in the drawing,) is brought under the roller i, which conducts it to the required place. A very little experience in the working of this apparatus enables a person so to regulate its operations as to complete the drying of damp grain by a single passage through it; such as varying the velocity of the air-forcer, the quantity of fuel in the stove, the supply of air through the ash-pit, the speed of the endless cloth, etc. the means of doing which are so well understood by mechanics as to render a description of them unnecessary in this place.