PRIMORDIAL OCEAX OF 0T7B GLOBE. 113 



carefully deduced by Dr. Krummel from a comparison of recent 

 soundings, is stiU perfectly arbitrary and admits of no verification. 



Taking the surface of our globe at 173,289,984 square miles, and 

 the total volume of water upon it, as given by Kriimmel, at 

 238,367,880 cubic miles, this volume of water, if spread uniformly 

 over the globe, would cover it to a depth of 1*383 mile ; and taking, 

 not 34 feet in depth as equal to the pressure of one atmosphere, but 

 36 feet (thus allowing for the diminished density of water at high 

 temperatures), the pressure due to 1*383 mile in depth would, at 

 sea-level, equal a barometric pressure (whether of water or vapour 

 it matters not) of 202*74 atmospheres. We therefore see that this 

 pressure so far transcends the limits of experiment that we cannot 

 even conjecture, in the present state of physical knowledge, the tem- 

 perature of steam that would correspond to it, or, what is the same 

 thing, we know nothing, even approximately, of the boiling-point of 

 water under such a pressure. 



It is matter of common knowledge that, leaving out of view some 

 minor conditions, such as whether the liquid be free from dissolved 

 air, the material of the vessel, capillarity, &c., which slightly vary 

 the result, water boils in an open vessel, the barometer being at 30 

 inches, at 212° Fahr., or 100° Centigrade ; or, in other words, it 

 boils at that temperature under a gaseous pressure which, in round 

 numbers, is equal to that of a column of water of about 34 feet in 

 height. 



It is also matter of common knowledge that this boiling-point of 

 water, or of any other liquid, is raised more and more if the liquid be 

 contained in a closed vessel (such as a steam-engine boiler), so that the 

 vapour already expelled may accumulate and its tension continually 

 augment. The boiling-point of any liquid is therefore only that 

 temperature at which vapour is freely expelled from it by ebullition 

 against the pressure, whether elastic or hydrostatic, of surrounding 

 bodies. Situated as we are upon the earth, we can only increase 

 this resistance by boiling water or other liquid in a closed vessel ; but 

 could we by any means increase the height of the barometric column 

 which measures the pressure of our atmosphere and of such water- 

 vapour as floats in it, no closed vessel would be necessary ; in other 

 words, the entire planet would become the closed vessel, and gravi- 

 tation alone would perform its function. Thus, for example, could 

 we remove from the ocean's surface a plate of water of such a thick- 

 ness as would represent a plate covering the whole globe to the 

 depth of about 34 feet, then whether the water therein remained 

 liquid or were in the state of vapour, water in an open vessel would 

 then boil at a greatly increased temperature, due, namely, not to one 

 atmosphere, but to two atmospheres ; and this would be true of a 

 second or third such plate of water removed from the ocean and 

 vaporized, the temperature necessary to effect this last being 

 derived from the heated globe itself, and the temperature continually 

 rising with the increase of the -sleight of vaporized water already 

 in the atmosphere. The relations between temperature and pressure 

 of steam have been experimentally investigated by llcgnault, and 



Q.J.G.S. No. 141. ' I 



