Tuesday, 3 February 2009

dters

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troylloyd said...

The only mine in Great Britain which yields plumbago, or black lead as it is called, suitable for pencil-making, is situated in one of the mountains at Borrowdale, in Cumberland, and is about 1000 ft. deep. This rare and very valuable mineral substance became the subject of continued robbery about one hundred and forty years ago, and is said to have enriched many persons resident in the neighbourhood. It was strongly guarded by the proprietors, but they were more than once overpowered by an infuriated mob, and possession of the mines was held for a considerable time by the desperadoes. When the owners again got possession, their carts, which conveyed the produce of the mine to Keswick, were always guarded by soldiers.

The entrance to the mine was afterwards protected by a strong building, consisting of a well-appointed guard room and three other apartments on the ground floor, in one of which was an opening into the mine, secured by a trap-door, through which alone the miners could enter. In another of these apartments, called the dressing-room, the miners changed their ordinary clothes for a working dress, and after six hours' work in the mine they had again to change their dress under inspection, lest some of this valuable substance might be concealed about them.

The plumbago, when perfectly cleaned, was packed up in casks and despatched to London, and there disposed of at monthly sales by auction, at the offices of the proprietors, in Thames Street, where it realised from thirty-five to forty-five shillings per pound, the annual sales ranging in value from £30,000 to £40,000 sterling.

Plumbago is found in small irregular nodules about the size and shape of a potato, and consists of carbon in a peculiar state of aggregation, with a small impregnation of iron.

COMPRESSING PLUMBAGO DUST; CASTING TYPE; TYPE-COMPOSING MACHINE, ETC

3 February 2009 at 21:13
mike di tomasso said...

grayphyte

5 February 2009 at 09:38

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