The plan, Fig. 2, shows the arrangement of the parts, g, g', and allows it to be seen that the pieces, g', act as wedges against the segments, g, and push these out so as to form a perfect circle. The molten metal cannot become oxidized in the mould, since it is shut off from contact with the external air by the cap, C, which covers it. Oxidation may, however, be further prevented by passing some deoxidizing or neutral gas into the mould. For this purpose the mould is filled before the casting is done with some such gas as illuminating gas, carbonic acid, nitrogen, or hydrogen. This improved process of casting may also be employed for objects which do not possess an exactly annular section. The moulds are then arranged eccentrically in a frame which is made to revolve rapidly during the cooling of the metal In this way the pieces are less strongly compressed at the places where they are nearest the center of rotation than a the points where the radius is greater. Figs. 3 and 4 show section and plan of an apparatus of this kind. The sand moulds are arranged in the frame, a b which revolves about the axle, c. In the moulds there are iron cores, h, which press the metal during rotation and thereby produce compact pieces. * * * * * APPARATUS FOR THE MANUFACTURE OF WOOD PULP. For manufacturing wood pulp Mr. Dresel employs an apparatus such as represented in Figs. 1 and 2, consisting of an upright cylindrical reservoir, A, supported on a frame by means of trunnions, z. This reservoir, which is of boiler plate, is furnished with a cover, D, which has in its center a piece of tubing, with stop-cock, C. A series of tubes, R, whose diameter and length are proportioned to the volume of the boiler, A, is filled with the liquid which is contained in the boiler, so as always to be able to rapidly produce a pressure of nine atmospheres or more by direct heating. The flanges of the tubing are provided with a cut-off of angle iron identical with that of the tube, D. By means of this arrangement the cocks and the flanges, E, permit of communication between the serpentine tubing, R, and the boiler being interrupted; while the heat developed by the fire-place, F, causes an active circulation in both the tubing and boiler. [Illustration: DRESEL'S WOOD PULP APPARATUS. Fig. 1] [Illustration: DRESEL'S WOOD PULP APPARATUS. Fig. 2]