1897.] NATURAL SCIENCES OF PHILADELPHIA. 13 



sank to 212°, and the earliest ocean must have formed at a much 

 higher tempei'ature. 



We have experimental evidence of the boiling point of water 

 under pressure up to a certain limit of temperature. Under a pres- 

 sure of one atmosphere, as is well known, water boils at 212° F. 

 With increase of pressure the boiling point rises, but not in an 

 equivalent ratio, since the energy of evaporation increases more 

 rapidly than that of pressure. For example, under five atmospheres 

 of pressure water boils at about 300° F. ; under fifteen atmospheres 

 it boils at about 400° F. ; under twenty-five atmospheres it boils at 

 about 440° F. I have given approximate temperatures, so as to 

 state them in round numbers, the actual temperatures differing 

 slightly from those stated. 



It is evident from the figures given, that as the temperature rises 

 the energy of evaporation steadily gains the ascendency over that of 

 pressure. At 300°, one hundred degrees of temperature must be 

 added to produce ten additional atmospheres of pressure. At 400° 

 ou ly forty degrees of temperature are needed for the same result. 

 Experiment has gone no further, and we are not aware at what rate 

 the temperature of the boiling point would increase under higher 

 pressures. But if we may judge from the rapidly accelerated in- 

 crease of evaporative energy with increase of temperature, it may 

 be that at some point between 600° and 800°, all the waters of the 

 ocean would be converted into vapor and form part of the atmos- 

 phere. 



At the boiling point of 440°, which yields twenty-five atmos- 

 pheres of pressure, one-twelfth of the oceanic waters would be con- 

 verted into vapor, and eleven-twelfths continue as water. A total 

 evaporation of the oceanic waters would produce a pressure of about 

 three hundred atmospheres, or 4,500 pounds on each square inch of 

 surface. The primeval pressure must have been still greater, since 

 much water which has sunk into the earth's crust and forms no part 

 of the present ocean must then have added to the volume of atmos- 

 pheric vapor. We cannot affirm at what limit of temperature this 

 great pressure would be overcome, but, from the rapid rate of in- 

 crease in evaporative energy observed between one and twenty-five 

 atmospheres of pressure, it seems not improbable that this limit 

 would be reached, as above said, at some point between 600° and 800°. 



At the period in question, when all the ocean was in the air, 

 the enormous pressure must have exerted an important influence 



