A mode of applying manufacturing processes to the preparation of black-lead is described by Dr. Ure as being adopted in Paris. The mineral, being reduced to a fine powder, is mixed with very pure powdered clay, and the two are calcined in a crucible at a white heat; the proportion of clay employed is greater as the pencil is required to be harder, the average being equal parts of both. The ingredients are ground with a muller on a porphyry slab and then made into balls, which are preserved in a moist atmosphere in the form of paste. The paste is pressed into grooves cut in a smooth board, and another board, previously greased, is pressed down upon it. When the paste has had time to dry, the mould or grooved board is put into a moderately heated oven, by which the paste, now in the form of square pencils, shrinks sufficiently to fall out of the grooves. In order to give solidity to the pencils they are set upright in a crucible and surrounded with pounded charcoal, fine sand, or sifted ashes; the crucible, being covered, is exposed to a degree of heat proportionate to the hardness required in the pencils, the harder pencils requiring the higher degree of heat. Some of the pencils are shaped in a curious manner: models of the pencils, made of iron, are stuck upright upon an iron tray, having edges raised as high as the intended length of the pencils; and a metallic alloy, made of tin, lead, antimony and bismuth is poured into the sheet-iron tray. When the alloy has cooled, it is inverted and shaken off from the model-rods, so as to form a mass of metal perforated throughout with tubular cavities corresponding in size with the intended pencil pieces; the pencil paste is introduced by pressure into these cavities, and when nearly dry the pieces shrink sufficiently to be easily removed from the cavities. The pencils just described are alike throughout all their thickness, but in the majority of English pencils there is a wooden holder to contain a narrow filament of black lead running down the middle. So long ago as the year 1618 this mode was adopted; for Sir John Pettus, who was deputy governor of the Borrowdale mine under Charles II, in his "Fleta Minor," while, speaking of black-lead says, that "Of late it is curiously formed into cases of deal or cedar and so sold as dry pencils, something more useful than pen and ink." In a general way modern black-lead pencils, are made by sawing cedar first into long planks, and then into smaller rods; grooves are cut out by means of a cutting machine moved by a fly- wheel to such a depth as will receive a small layer of black-lead; the pieces of the mineral are cut into thin slabs and then into rods the same size as the grooves, into which they are inserted; the two halves of the case are then glued together, and the whole is turned into a cylindrical form by means of a guage.