The vessel containing the liquid to be evaporated, (see [Plate 12], [fig. 6],) is long and shallow, and the liquid rises nearly to it’s brim. In this vessel is placed a long hollow drum A B, covered with open wire-work, or any kind of cloth of a very loose texture. This drum turns slowly, on the hollow centre C, to which is fitted a stuffing box and tube, connecting the drum A B, with the pump P; the latter worked by any convenient power. The pump then, drives air, either hot or cold into the drum, and thence through the interstices of it’s texture; where it comes in contact with the liquid at an indefinite number of points, breaks the films formed by the liquid, and, saturated thereby, passes into the open air; thus occasioning a rapid evaporation, which might be increased either by heating the liquid or the injected air, or both, ad libitum. The whole idea consists in the multitude of points of contact between the liquid and the drying medium.
OF
A CUTTING OR GRATING MACHINE,
For Green Roots, Tobacco, &c.
This Machine is composed of a perpendicular axis A B, [fig. 7], driven with considerable velocity by any proper geering. C D is a vessel formed something like a shoe with the toe cut off: its entrance D is concentric with the shaft A B, and a weight m, fastened to it’s side, equilibrizes the weight of the eccentric part C. Around this vessel, and concentrically with it, is placed a cylindrical rasp or grater E F, consisting, here, of a number of blades so grooved on one surface as that by grinding them obliquely on the edge, each one shall form a line of sharp teeth, which, combined with those of the other blades, constitute a rasp similar to that used for powdering dye-woods; with this difference however, that these blades have interstices between them, through which the pulp escapes outwards, and thus the rasp is kept clean at all times. When this Machine is used the roots are merely thrown into the vessel D as into the hopper of a mill, and they are pressed against the rasp by their own centrifugal force; which is made as strong or weak as desired, by the greater or less velocity of the Machine.
This Machine owes its origin to the decree of the French Emperor, for encouraging the making of sugar from beet-root. With the other mechanicians of Paris I was called upon, by a house engaged in that trade, to try my hand upon it; and this Machine was the result. It acts fast and well; and from being less liable to clog, than most of the others, is I believe superior; though this was never proved by any comparative experiment. If it were desired to cut any substance with this machine, the blades would be sharp knives, instead of being toothed; and they would be placed obliquely to the circumference: but the process of grating is that for which it was exclusively designed.