I can, however, point out no mention of our plumbago in the works of the old Italian artists. Armenini, who wrote at the end of the sixteenth century, relates how pupils were taught to draw a hundred years before his time[970]. He says that they made the first sketches with piombo over cannella col lapis nero, and afterwards filled them up with a pen. But when his whole description is read, there can remain no doubt that the substance here meant is black chalk. Baldinucci, who did not write till 1681, has introduced particularly into his dictionary matita rossa, nera, and also lapis piombino; and says that the last-mentioned is an artificial production, which gives a leaden colour, and is employed for drawing. It is evident therefore that the author here alludes to plumbago, which was then very common. But when Bottari says[971] that artists first began to use red and black chalk in the time of Vasari, whereas lapis piombino only was employed before that period, he has named plumbago, commonly used in his time, instead of the metallic pencil which was called stile. If I am not mistaken, the Italians have no proper appellation for black lead, but call it sometimes matita and sometimes piombino.
[Great difficulty was formerly experienced in protecting the Borrowdale black-lead mine from robbery. At present, the treasure is protected by a strong building, consisting of four rooms upon the ground floor; and immediately under one of them is the opening, secured by a trap-door, through which workmen alone can enter the interior of the mountain. In this apartment, called the dressing-room, the miners change their ordinary clothes for their working-dress as they come in; and after their six hours, post or journey, they again change their dress, under the superintendence of the steward, before they are allowed to go out. In the innermost of the four rooms two men are seated at a large table, sorting and dressing the plumbago, who are locked in while at work, and watched by the steward from an adjoining room, who is armed with two loaded blunderbusses. In some years the net produce of the six weeks’ annual working of the mine has, it is said, amounted to from 30,000l. to 40,000l.
An inferior kind of plumbago is imported from Mexico and Ceylon; and a composition with which more common pencils are manufactured is made of a mixture of plumbago-powder, lamp black and clay.
A useful and convenient application of the black lead in the form of minute cylinders which slightly projected from a cylindrical cone, and which was fitted to a pencil-case, was patented in 1822 by Mr. Mordan, and has come into general use: the cylindrical form of the plumbago is produced by passing square strips of it through holes in a ruby, somewhat in the manner of wire-drawing. It is stated that the supply of plumbago from the Cumberland mine is almost exhausted; fortunately, a process has been devised by which the same firmness and equality may be communicated to the powder by compression. This is effected by carefully washing and grinding the dust obtained in sawing plumbago into thin plates, sifting it through spaces less than the 1/50000th part of an inch, and placing it under a powerful press, on a strong die or bed of steel, with air-tight fittings. The air is then pumped from the dust, and while thus freed from air, a plunger descends upon it and it becomes solidified. The power employed to perform this operation is estimated at 1000 tons, several blows having been given, each of this power. This process was invented by Mr. W. Brockedon, the talented draftsman of Alpine and Italian scenery.]
FOOTNOTES
[958] Plin. lib. xxxiii. 3, sect. 19.
[959] A plate of this kind was called παράγραφος, also τροχαλὸς, γυρὸς, κυκλοτερὴς, which last appellation denotes the form. The Romans, at least those of later times, named this lead præductal. The ruler by which the lines were drawn was called κανὼν and κανονίς. Thus the ruled sheet which Suffenus filled with wretched verses is styled by Catullus membrana directa plumbo. Pollux has παραγράφειν τῇ παραγραφίδι. See Salmasius ad Solinum, p. 644, where some passages, in which these leaden plates are described, are quoted from the Anthologia.
[960] Versuchs e. System d. Diplomatik. Hamb. 1802, 8vo, ii. p. 108.
[961] Diplomatique-pratique: à Metz, 1765, 4to, p. 62.
[962] De Metallicis, lib. iii. Rome, 1596, or Norib. 1602.