The crater of Tangkuban-Prahu, another of the volcanoes of Java,
presents a remarkable appearance. On approaching its edge, nothing
is seen but an abyss, from which dense clouds of vapour continually
arise, with hideous sounds, like the steam rushing from the open
valves of hundreds of steam-engines. This great abyss consists
really of two craters, separated the one from the other by a narrow
ridge of rock, to which it is possible to descend and view them
both. Each of them is elliptical in form, and surrounded by a
crater-wall. That of the western, which the natives call the
poison-crater, is a rapid slope nearly a thousand feet in depth,
and is densely covered with brushwood almost to the bottom. The
flat floor of this deep basin is continually sending out vapours,
and in its centre is a pool of boiling water of a sulphur yellow
colour. The floor itself is nothing but a crust of sulphur full of
rents and holes, whence vapours constantly arise. This crust covers
a surface of boiling hot bitter water, and by breaking it beautiful
crystals of sulphur may be obtained.

The eastern is called by the natives the king's-crater; its walls
are only between five and six hundred feet in depth, and are
perfectly bare from top to bottom. The surfaces of the rocks
composing them are grayish white, an effect produced upon them by
the action of the vapours, to which they are continually exposed.
The bottom of this crater consists of mud mixed with sulphur; but
round the edges are some stones and hard masses. These are the
remnants of an eruption which took place from this crater in 1846,
when there was thrown up a great mass of sulphurous boiling mud,
accompanied by quantities of sand and stones. This mountain,
therefore, seems to be also more of the nature of a mud volcano,
than of one which throws out burning lava.