This substance is, perhaps, better known by the familiar appel

lation of German tinder, and is chiefly employed in procuring a light speedily, as it ignites immediately with a feeble spark from the flint and steel, or by condensation of atmospheric air, and burns with slow and smouldering heat for a considerable time. It is formed of a spongy excrescence, or mushroom, found on old trees, particularly the oak, ash, and fir. This is washed and boiled in fair water, and afterwards beaten by a mallet until it resembles very spongy leather; it is then soaked in a saturated solution of saltpetre, and dried in an oven. A good substitute for this may be formed of coarse brown paper, soaked in the solution of saltpetre, and dried in an oven.