18 Account of a Descent 
In traversing the surface of the crater, we perceived a 
focus half covered by a large mass of pumice stone, and. 
which, from its whole circumference, emitted a strong 
heat. The thermometer placed at first at the entrance 
of it, and then immersed to as great a depth as the na» 
ture of the ground and the heat would admit, never rose 
higher than 22 degrees. This singularity surprised us, 
but we were not able to explain it. 
The volcanic productions which we observed in the 
whole crater were lava, exceedingly porous, and which 
the fire in certain places had reduced to scoriae. It was 
of a dark brown colour, and sometimes reddish, but it is 
rare to find any white. The substances nearest the spi- 
racles are all covered or impregnated with sulphur. This 
mineral is found very often in a state of oxygenation. It 
is sometimes white, and sometimes of a yellowish colour, 
and the sharp and pungent impression it leaves on the 
tongue sufficiently indicates the state in which it is. The 
burning focus, of which we have spoken, produces the 
same results. Borne basaltic lava is also found, but in 
small quantity; one specimen only, of a considerable- 
weight and beautiful polish, attracted our attention. 
On the north side of the crater there are two large fis- 
sures, one of which is 20 feet in depth, and the other 
about 15. They are shaped like an inverted cone. The 
matter with which they are covered is entirely similar to 
that on the rest of the surface. They emit neither smoke 
nor heat ; yet some sulphurous productions plainly show 
that the fire in these places has not long been extinct. 
When we had finished these few observations, it was 
necessary that we should think of returning. The de- 
scent is far less laborious than the ascent ; for it is diffi- 
cult to climb eminences where the points of support are 
so moveable. Besides, people cannot ascend hut one at 
a time in succession, after long intervals, for fear of bury 
