S94 Dr Gosse cni the Baths St Filippo ^ and the formation 
The surfaces of these fissures are also penetrated by sulphuric 
acid, which renders them sour to the taste. 
Few vegetables grow on this soil. Small shrubs of Biioous 
sempervirens, or a few grasses only, are distributed over its 
surface, and the leaves of the huxus have all a yellowish-brown 
colour. The northern declivity, particularly in the course of 
the rivulet, is thickly covered with vegetables and small trees. 
The soil here is of a dark colour, the result either of vegetable 
decomposition, or of the different nature of the earthy substan- 
ces that compose the lower part of the hill. Vineyards have 
not succeeded near the village j even in transported soil ; which 
seems to arise from the baneful emanations diffused through the 
air, rather than from defects in the soil. 
The west end of the hill has a rounded form, and is separat- 
ed from the neighbouring mountain by tlie small torrent above 
mentioned, the bed of which is filled mth calcareous rocks from 
above. Crossing by a small bridge the rivulet at this part, the 
appearance of the surface is entirely different. Large masses 
of the calcareous deposit called Travertine, 20 or SO feet thick, 
presenting sharp edges, and spread in all directions, indicate the 
existence of an ancient spring at a greater height. In going 
100 yards higher up the mountain, the travertine is found in 
regular layers, which seem at one time to have been joined with 
those of the hill below. At this part I met with the siliceous 
stalactites discovered by Professor Sand ; they have a mamillary 
form, a pearly colour, are shining and semitransparent, and 
cover the lower surface of the layers of travertino to the thick- 
ness of |th of an inch. The travertino of St Filippo is not very 
porous, but hard, and resists the destructive action of time and 
weather. It is of a- greyish colour outside, but when broken 
has a whitish and somewhat shining appearance. Carbonate of 
lime enters principally as its component, and the presence of 
silica is not to be denied, at least in some parts of its surface, 
as appears by what we have already mentioned. It belongs to 
the ancient water deposits of hot springs in Italy, which, I 
have observed, seem in general to have a different composition 
from those of recent date, being more dense, more solid and 
abundant. In some other places where travertino is found, the 
warm springs have disappeared, or those which yet exist have 
ceased to deposit earthy matter. 
