NATURAL PHENOiMENA. 
57 
of gas, flow from tlie small basins at tlie summit, which 
are filled with water. The mud, though usually cold, is 
sometimes at a high temperature, as at Damak, iu the 
province of Samarang, in the Island of Java. The gases 
that are developed with loud noise differ in their nature, 
consisting, for instance, of hydrogen mixed with naphtha, 
or of carbonic acid, or, as Parrot and myself have shown 
(in the peninsida of Taman, and in the Volcancitos de 
Tiu’baco, in South America), of almost pure nitrogen. 
“ Mud volcanoes, after the first violent explosion of 
fire — which is not, perhaps, in an equal degree common 
to all — present to the spectator an image of the uninter- 
rupted but weak activity of the interior of our planet. 
The communication with the deep strata in which a 
high temperature prevails is soon closed, and the cold- 
ness of the mud emissions of the salses seem to indicate 
that the seat of the phenomenon cannot be far removed 
from the surface during their ordinary condition.” 
The most interesting and valuable phenomenon we 
have ill Trinidad is the Pitch Lake. It is a large tract 
of pitch, like a lake, of about a mile in diameter. It is 
intersected by a net-work of fissiu’es, caused by the up- 
heaving of the pitch. These fissures are, esjiecially in 
the wet season, full of sweet limpid water. The centre 
of the lake is in a boiling state, while the outer edges, 
upon a wet or sunless day, are sufficiently hard to 
allow of man or horse walking over it. It is impossible 
to say how deep this immense body of bitumen may 
descend — whether it is connected with the interior of 
the earth, or Avhence the heat proceeds which keeps the 
pitch in the centre in a semi-boiling state. 
“ The centre of the lake,” says Dr. Deverteuil, — “ the 
pitch-pot or chaudiere, as it is called — is at all times so 
soft that it would be impossible to venture on it without 
incurring the danger of being engulphed. There a slow 
and constant bubbling and puffing is perceptible, accom- 
panied by emissions of gaseous substances and the 
throwing up of a yeUowisli mud, quite cold, and of an 
