164, EFFECTS o HEAT 
carbonic acid} would be very much increafed by that union 
and by the ftiffnefs or tenacity of the fubftance. We have 
feen numberlefs examples of this power in the courfe of thefe 
experiments, in which barrels, both of iron and porcelain, 
whofe thicknefs did not exceed one-fourth of an inch, have 
exerted a force fuperior to the mere weight of a mile of fea. 
Without fuppofing that the fubftance of a rock could in any 
cafe act with the fame advantage as that of a uniform and con- 
nected barrel ; it feems obvious that a fimilar power muft, in 
many cafes, have been exerted to a certain degree. 
We know of many calcareous mafles which, at this mo- 
ment, are expofed to a preffure more than fufficient to accom- 
plith their entire fufion. The mountain of Saleve, near Geneva, 
is 500 French fathoms, or nearly 3250 Englith feet, in height, 
from its bafe to its fummit. Its mafs confifts of beds, lying 
nearly horizontal, of limeftone filled with fhells. Independent- 
ly, then, of the tenacity of the mafs, and taking into account 
its mere weight, the loweft bed of this mountain, muft, at this 
moment, fuftain a preflure of 3250 feet of limeftone, the fpecific 
gravity of which is about 2.65. This preflure, therefore, is equal 
to that of 8612 feet of water, being nearly a mile and a half of 
fea, which is much more than adequate, as we have fhewn, to 
accomplifh the entire fufion of the carbonate, on the appli- 
cation of proper heat. Now, were an emanation from a 
volcano, to rife up under Saleve, and to penetrate upwards 
to its bafe, and ftop there; the limeftone to which the lava 
approached, would inevitably be foftened, without being cal- 
cined, and, as the heat retired, would cryftallize into a faline 
marble. 
Some other circumftances, relating to this fubje@, are very 
deferving of notice, and enable us ftill further to compare the 
ancient and modern operations of fire. 
Ir 
