PENCILS are instruments for writing, drawing, and painting, and they differ as much in their construction as in the uses to which they are applied. Probably the pencil was the first instrument used by artists, and consisted then of lumps of colored earth or chalk simply cut into a form convenient for holding in the hand. With such pencils wero exe cuted the line-drawings of Aridices the Corinthian, and Telephones the Sicyonian, and also the early one-coloral pictures, or inonoeltroinata, of the Greeks and Egyptians; but as wet colors began to be used, small fine-pointed brushes would be required. and we find it recorded that as early as the 4th c. Ite„ several Greek artists had rendered the art of painting with hair-pencils so famous, that of their pictures sold for vast sums of money. There are now in use the following kinds of pencils: hair-pencils, black-lead pencils, chalk-pencils, and slate-pencils. The first are used for painting or writing with fluid colors, either oil or water, and in China and .Japan are employed almost entirely instead of pens for writing; the color used being the black or brown pigment obtained from various species of sepia or cuttle-fish. The manufacture of hair-pencils is of great importance, and requires much care and skill. The hairs employed arc chiefly those of the camel, badger, sable, mink, koliuski, fitch. goat, and the bristles of hogs; and the art of pencil-making requires that these hairs shall be tied up in cylindrical bundles, so nicely arranged that all their naturally fine points shall be in one direction, and that the central one shall project the furthest, and the others in succession shall recede, so that, collect, ively, the whole shall form a beautifully smooth cone, the apex of which Is a sharp point. Black-lead pencils are made of graphite or plumbago, which contains no lead whatever in its composition, but is in reality almost pure carbon. See BLACK-LEAD. Tho misnomer is probably owing to the fact that, previous to the employment of graphite for =kilti pencils, common lead was used, and this was the case even within the present century: Consequently, as the plumbago, with its black streak, offered a contrast to the pale one of the lead, it was called in contradistinction The best graphite for drawing-pencils is found in the Cnmberland mines, which have long been celebrated. Within the last twenty years, however, vast deposits of this mineral, of a very fine quality, have been discovered in Siberia and other parts of the Russian empire. Inferior qualities are found in Austria and Prussia, in Ceylon, and various parts of North America; but they are rarely used in pencil-making, except for very inferior kinds. Black-lead is rarely sufficiently free from sand and other foreign
ingredients to be used without preparation; it is therefore generally ground fine, and levigated or washed until it is pure, and again formed into solid blocks by means of enormous pressure, generally in hydraulic presses; these blocks.are then sawn into thin plates about the sixteenth of an inch in thickness, which are again cut across, so as to form them into small square sticks.
It may appear a very simple process to press the powdered graphite into blocks, but it was found so difficult in practice as almost to prevent the employment of this method, which has led to immense improvement in pencil-making. It was found at first that the difficulty of pressing out the containedair was so great that the presses were broken under the weight required; pressure in a vacuum was then tried, but the difficulty of applying it was found almost insurmountable, and it was certainly unprofitable. Mr. Brokedon of London, who has long been famous for his pencils, at last surmounted the, difficulty by an ingenious and very simple process. This consists in compressing the black-lead into blocks 2 or 3 in. square, with only moderate pressure; these are then coated over with paper, well glued, so that when dry the covering is air-tight. A small hole is now made through this coating on one side, and several of these cubes of black lead are put under the receiver of an air-pump, and the air being exhausted completely from them the orifice in each is closed by an adhesive wafer, which prevents the return of the air when they are taken out of the receiver. They are next placed under the hydraulic press, and a well-sustained and regular pressure is brought to bear upon them for 24 hours, after which they are found t he so completely consolidated, that in cutting them the substance is equal in density to the best specimens of unprepared graphite. There is so large a variation in the color of various qualities of black lead that by a judicious mixture of them, when in the powdered state, almost any shade of darkness can be procured; but instead of thus carefully combining different qualities of graphite it B. a common practice to add sulphur or sulphuret of antimony, and by heating to pro cure the desired degree of blackness. For very inferior pencils the worst quality of black lead is mixed with black chalk and size, or gum-water, and formed into a paste, of which the pencil is made.