a et TIO “ a 
« 
Hare’s Blowpipe. 287 
ecean of lava. ‘The only difficulty this subject presents, is 
that of explaining the nature of volcanic fires, the inces- 
sant existence of which is self-evident. 'The access of the 
atmosphere is necessary to fire in all its ordinary forms. In 
that of volcanoes, it appears to subsist without any adequate 
supply of this principle. Dr. Clark, far from relieving us 
‘from this difficulty, has increased it, by alleging the neces- 
sity of another aeriform substance. A better solution, as 
should suppose, was long ago afforded by a reference to the 
combustion of metals by sulphur, in the vapour of which 
some of them burn more readily than in the atmosphere. 
Lately the metallic origin of earthy matter being discov- 
ered, it has been supposed possible, that at some distance 
from its surface the globe may consist of a great metalloidal 
nucleus, which acting on water, may produce intense igni- 
tion. Those who have seen the consequences of moisten- 
ing quick lime, may easily conceive that tremendous effects 
might ensue from reaction between water and calcium, or 
any of the same family of substances. In this case hydro- 
gen would be produced, but there would be no oxygen.— 
Of the existence, however, of subterraneous fires in volea- 
nic regions there can be no doubt, whatever may be the 
theory of their origin. ‘The obvious proximity of s 
3 
_Tivers, and even of the sea itself, with the well known force 
may be accomplished. The principle of the apparatus 
used by Dr. ©. will be found the same as that of the air 
