Miscellanies. 177 
done by infiltration, and the results most probably depend on the 
nature of the water—that is, upon what the water contains dissol- 
ved, &c. 
MISCELLANEOUS INTELLIGENCE. 
1. Plumbago and Black Lead pencils.—There is only one~pur- 
pose to which this form of carbon is applied in the solid state, viz., 
for the manufacture of black lead pencils, and its adaptation to this 
end depends upon its softness. In the state of a powder, plumbago. 
is used to relieve friction. Its power in this way may be illustrated 
by rubbing a button first on a plain board, five or six times, and ap- 
plying it to a bit of phosphorus, the latter will immediately burn. 
When rubbed on a surface covered with plumbago, double or triple 
the friction will be required to produce the same effect. One of the 
most remarkable circumstances connected with the plumbago is the 
mode in which it is sold. Once a year the mine at Borrowdale is. 
opened, and a sufficient quantity of plumbago is extracted, to sup- 
ply the market during the ensuing year. It is then closed up, and 
the product is carried in small fragments of about three and four 
inches long, to London, where it is exposed to sale, at the black 
Jead market, which is held on the first Monday of every month, at a 
public house in Essex street, Strand. The buyers, who amount to 
about seven or eight, examine every piece with a sharp instrument 
to ascertain its hardness—those which are too soft being rejected. 
The individual who has the first choice pays 45s. per pound ; the 
others 30s. But as there is no addition made to the first quantity 
in the market, during the course of the year, the residual portions 
are examined over and over again, until they are exhausted. The 
annual amount of sale is about £3000. ‘There are three kinds of 
pencils, common, ever-pointed, and plummets. ‘The latter are com- 
posed of one-third sulphuret of antimony and two-thirds plumbago. 
The Ist part of the process is sawing out the cedar into long planks, 
and then into what are technically called tops and bottoms. The 
2d, sawing out the grooves by means of a fly-wheel. The 3d, 
scraping the lead ona stone; having been previously made into 
thin slices, to suit the groove ; introducing it into the groove, and 
scratching the side with a sharp pointed instrument, so as to break 
it off exactly above the groove. The 4th, glueing the tops and bot- 
toms together, and turning the cedar cases in a gauge. 
Vou. XXXI.—No. 1. 
