530 PENCIL MANUFACTURE 



mentfl of plumbago as by grinding them, melting them with sulphur or antimony, 

 and the like ; but few of these have been attended with any success. 



The late Mr. Brockedon was long occupied in seeking for some method which 

 might enable him to employ the pure powder of black-lead without cementing it by 

 any substance, which inevitably injures the quality. He endeavoured to render the 

 powder coherent by submitting it to enormous pressure ; but the different machines 

 and apparatus he at first made use of for this purpose, however strongly they wero 

 made, were, broken under the pressure, and his endeavours were thus unsuccessful, 

 until 'the happy idea suggested itself of operating in a vacuum. But it was ex- 

 tremely difficult, if not impossible, to introduce under the receiver of an air-pump an 

 apparatus for compressing the powder of graphite. Mr. Brockedon overcame this 

 difficulty by an arrangement as simple as it is easily executed ; for, after having com- 

 pacted the powder by a moderate pressure, and thus reduced it to a certain size, he 

 enclosed it in very thin paper glued over the whole surface. He then pierced it in 

 one place with a small round hole permitting the escape of the air from within, when 

 the block thus prepared was placed under an exhausted receiver, and the air having 

 been removed, the orifice was closed with a little piece of paper (a small adhesive 

 wafer was usually employed for this purpose), and in this state it was found that it 

 might be left for twenty-four hours without injury. Being submitted to a regulated 

 pressure once more, the different particles became agglomerated, and an artificial 

 block of graphite (see GKAPHITE) was produced by simple pressure, as solid as the 

 specimens obtained from the mine. 



The artificial masses of plumbago thus obtained owed much of their character to 

 the extreme fineness to which the plumbago was reduced by previous grinding under 

 rollers. In this manner a great deal of useless plumbago is worked up into excel- 

 lent black-lead pencils. The different degrees of darkness in drawing pencils should 

 be secured by the selection of specimens of plumbago of varying degrees of density. 

 It is, however, commonly obtained by combining, with the plumbago, sulphur, or sul- 

 phuret of antimony, and by subjecting the plumbago to the action of heat. In the 

 commoner kinds of pencil a very heterogeneous mixture is employed ; indeed, many 

 pencils are little more than black chalks. 



The pencil works at Keswick consist of a house of several stories, in the lower of 

 which is a huge water-wheel turned by the Greta, outside being the cedar wood ready 

 for use. The quantity of cedar consumed annually by the establishment is 4,000 cubic 

 feet. These cedar logs are sawn into planks, and then a circular saw cuts the planks 

 into smaller pieces, preparatory for the grooving-engine ; this grooving-engine consists 

 of two revolving saws, going at inconceivable speed ; one saw cutting the slips of wood 

 into narrow square rods, and the other making a groove along the rod and cutting to 

 size at the same time ; adjoining the grooving apparatus is a circular saw, cutting 

 slips of cedar as covers to the grooved lengths. 



The plumbago, if good, needs no refining; it is used precisely in the condition in 

 which it leaves the mine. To ascertain its qualities each piece is scraped with^ the 

 edge of a knife, besides being otherwise tested ; and in proportion as there is no 

 gritty particles in it, so is it the more valuable. Some pieces are harder, some a little 

 darker in colour than others ; and according to these peculiarities, they are employed 

 for pencils of various hardness and shades. The whole knack of pencil-making seems 

 to depend on the detection of these niceties in the bits of lead, and also, of course, in 

 their honest adaptation to the varieties which are dealt out to the public. Plumbago of 

 an impure kind is ground to powder ; the grit, as far as possible, separated from it, and 

 the cleansed material, mingled with a cohesive liquid, is dried and pressed into hard 

 lumps for use. This process, however, is applied principally, if not exclusively, to 

 the plumbago imported from India, and only in reference to pencils of the commonest 

 sort. Pencils made with such stuff are valueless to artiste ; for independently of their 

 want of tone, they are never altogether free from grit. The best pencil is one 

 made from genuine Borrowdale lead, pure from the mine, and adapted by a skilful 

 manufacturer to its assigned purpose. The mode of preparing the pieces of good 

 plumbago for the pencil is very simple. All the bits, with their surface merely 

 scraped, are glued to a board, in order to fix them in a position for being sawn. 

 When so fixed they are brought under the action of a saw, which divides them into 

 thin slices or scantlings. These slices are now handed to the fitter. This is an ope- 

 rative who, with a lot of grooved rods before him, sticks slices of the lead into grooves, 

 snapping off each slice level with the surface, so as just to leave the groove properly 

 filled. In the making of a single pencil, perhaps as many as three or four slice lengths 

 are required ; but however many, each slice is fitted exactly endlong with another. BO 

 as to leave no intervals. The rods being thus filled, are carried to the fastener-up. This 

 person glues the cedar covers or slips over the filled rods ; and having got a certain 

 number arranged alongside of each other, he fixes them tightly together, and lays 







