( 3*3 ) TWENTY-NINTH SPECIES. Lava. v Lava.—Werner. * This fpecies is by Werner divided into two fub fpecies. i. Slag Lava. 2. Foam Lava. FIRST SUBSPECIES. Slag Lava. . Schlackige Lava,—Werner. External Characters. Its colour is greyifli black, which paffes into yel- lowifh grey, greenilh grey, and fometimes into green- black. It is externally fpotted, reddifli, yellowilh brown, and grey j when the lulphureous vapour has adled 3 D 2 much