Lamp-Black, is one of the black colouring matters, the preparation of which has already been stated, vol. ii. p. 35.
We again introduce this sub-stance, as it possesses several remarkable properties : thus, lampblack is liable to undergo spontaneous inflammation, if it be kept for some time closely confined, and be afterwards suddenly exposed to the air: there have been instances of its taking fire in shops, and occasioning the most distressing scenes of conflagration. But, when lampblack is combined with oil, so as to form a black varnish, it appears from various experiments, that bodies painted with this compound resist the effects of electricity in a most surprizing degree; and that they have, in a variety of cases, even repelled lightning.
In 1708, a patent was granted to Mr. William Row, for a new-invented mineral lamp-black. This is obtained from pit coal, or any other kind of fossil coal; the blackest particles arising from the smoke of which, are deposited in certain tubes, or receptacles, whence they are removed in the course of six or eight days, and packed up for sale. For the particulars of this unexpired patent, the inquisitive reader will consult the 10th vol. of the repertory, etc. where the process is duly specified.