Civilisation : Its Cause and Cure 



perfect gases only. This idea of a perfect gas of 

 course involved the assumption that gases, as they 

 get farther and farther removed from their liqui- 

 fying point, reach at last a fixed and stable condi- 

 tion, when no further change in their qualities 

 takes place — at any rate for a very long time — and 

 Boyle's law was supposed to apply to this condition. 

 Since then, however, it has been discovered that 

 there is an ultra-gaseous state of matter, and on 

 all sides it is becoming abundantly clear that the 

 change in the condition of matter from the liquid 

 state to the ultra-gaseous state is perfectly continuous 

 — through all modifications of liquidity and con- 

 densation and every degree of perfection and imper- 

 fection of gasiness to the utmost rarity of the 

 fourth state. At what point, then, does Boyle's 

 law really apply ? Obviously it applies exactly 

 at only one point in this long ascending scale — at 

 one metaphysical point — and at every other point 

 it is incorrect. But no gas in Nature remains or 

 can be maintained just at one point in the scale 

 of its innumerable changes. Consequently, all 

 we can say is that out of the innumerable different 

 states that gases are capable of, and the innumerable 

 different laws of compressibility which they there- 

 fore follow, we could theoretically find one state 

 to which would correspond the law of compressi- 

 bility called Boyle's law ; and that, if we could 

 preserve a gas in that state (which we can't), Boyle's 

 law really would be true just for that case. In 

 other words, the law is metaphysical. It has no 

 real existence. It is a convenient view or fiction, 



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