340 FORMATION OF PRIMITIVE MOUNTAINS. 



to diminish the mean height of the sea 32 feet, in order 

 to have a pressure of an atmosphere more ; and it is by 

 this pressure that the degree of temperature at which 

 water boils will also be raised higher. M. Laplace 

 judges from the height of the sea during flowing and 

 ebbing, that the mean depth of the sea is about 96,000 

 feet. Supposing three-fourths of this mass of water 

 were converted into vapour, the pressure of this vapour 

 would be nearly equal to 2250 atmospheres ; and this 

 pressure would so augment the degree of heat at which 

 water enters into ebullition, that the primitive mountains 

 might be in a state of fusion, without the water with 

 which they are covered being heated to the boiling 

 point ; for the water which is not converted into vapour, 

 and whose quantity is a fourth of the whole mass of 

 vapour, according to the supposition which we have 

 made, would cover the whole earth, because water ex- 

 pands in increasing proportion if the temperature be 

 raised, and because the expansion of water is much 

 greater than that of the mass of our primitive moun- 

 tains ; and, consequently, according to this supposition, 

 our primitive mountains are formed, covered with red 

 hot water. The great pressure of so many atmospheres 

 necessarily modifies the reciprocal affinities of the sub- 

 stances which compose the primitive mountains. 



Primitive mountains are distinguished from volcanic 

 productions in this, that 'the lime and magnesia, which 

 in them are combined with carbonic acid, form with the 

 silex silicates and bisilicates. It is necessary that the 

 silex, which, under the ordinary pressure, and at an ele- 

 vated temperature, expels the carbonic acid, exercise no 

 influence under the pressure of so many atmospheres ; 



