Plate I: Mineralogy, Carbon Black

The plate represents the interior of a room or round tower sectioned along one diameter. The chamber is covered by a conical roof at the apex of which is fixed a pulley a over which passes a cord a b from which is suspended a hood or cone of cloth A C B whose base, held open by a circlet, brushes against the inside of the walls of the tower A B E B. A furnace communicates with the interior of the tower whose windows g and door f must be very well-fitting. This furnace G E d H I should have been shown outside the tower in such a way that the wall G H of the furnace rested against the wall B E so that the cone would have free passage to move right down the interior walls of the tower to the floor and so collect the soot (which is the smoke black) contained in its interior. The arrangement is easy to understand if one imagines that the chimney H I is removed as far down as the inverted funnel and that the furnace is outside the building as has been pointed out.

The front of the furnace is pierced by three openings E e d . The first, E, is that of the ash pit, the second e is the hearth and is at the level of the grate on which the wood is placed; the third opening is the one through which resinous material whose combustion produces the smoke black is put into the cauldron. See the article Smoke black in the XI Volume, to which it should be added that smoke black is miscible with water if it is first soaked in vine spirit of brandy before it is mixed with water colours.