DIES, in mechanical manipulation, are tools by which the threads of screws are cut. They consist of pieces of steel held in a suitable socket or stock, and so formed that their inner sides form parts of a hollow cylinder, in which is cut a female or hollow screw, which would fit to the screw desired to be cut. The edges of the joints formed between the dies are sharpened, and notches are cut in the dies themselves to make additional cut ting edges. By turning the dies upon a rod, the cutting edges of their threads, cut out the spaces between the threads of the screw ; and by keeping the dies pressed closely round, tightening screws being fitted to the stock for the purpose, a perfect screw is soon cut upon the rod. SUGAR, is now most commonly effected by the centrifugal drainer or separator, which consists of a hollow cylinder, whose sides are made of porous material, such as wire cloth. This
cylinder has a very rapid rotary motion given to it, and on the sugar being placed in it, it is thrown by centrifugal force against the sides of the cylinder, and all the moisture or molasses expelled, passing through the wires into an outer easing, at the bottom of which there are suitable channels to draw it off. This is a great improvement over the old plan of allow ing the sugar to stand, till the moisture had drained out through the bottom, as it not only separates it more perfectly, hat effects an incalculable saving in time. The latest improvement in the centrifugal separator, is providing it with a false bot tom, which, after the separation is per fect, ascends to the top of the cylinder and empties it, thereby obviating the ne cessity of stopping it for that purpose. It can be charged while revolving.