468 



Prof. J. C. Maxwell on Molecules. 



in ev^ry molecule of hydrogen is a fact of a very different order. 

 We have here a particular distribution of matter — a collocation 

 — to ase the expression of Dr. Chambers, of things which we 

 have no difficulty in imagining to have been arranged otherwise. 

 The form and dimensions of the orbits of the planets, for in- 

 stance, are not determined by any law of nature, but depend 

 upon a particular collocation of matter. The same is the case 

 with respect to the size of the earth, from which the standard of 

 what is called the metrical system has been derived. But these 

 astronomical and terrestrial magnitudes are far inferior in scien- 

 tific importance to that most fundamental of all standards which 

 forms the base of the molecular system. Natural causes, as we 

 know, are at work which tend to modify, if they do not at length 

 destroy, all the arrangements and dimensions of the earth and 

 the whole solar system. But though in the course of ages ca- 

 tastrophes have occurred and may yet occur in the heavens, 

 though ancient systems may be dissolved and new systems 

 evolved out of their ruins, the molecules out of which these 

 systems are built — the foundation stones of the material uni- 

 verse — remain unbroken and unworn. They continue this day 

 as they were created — perfect in number and measure and weight; 

 and from the ineffaceable characters impressed on them we may 

 learn that those aspirations after accuracy in measurement, 

 truth in statement, and justice in action, which we reckon among 

 our noblest attributes as men, are ours because they are essential 

 constituents of the image of Him who in the beginning created, 

 not only the heaven and the earth, but the materials of which 

 heaven and earth consist. 



Table of Molecular Data. 







Hy- 



drogen. 



Oxygen. 



Car- 

 bonic 

 oxide. 



Car- 

 bonic 

 acid. 



Rank J 



Mass of molecule (hydrogen = 1 ) 



Velocity, mean (square metres 



per second), at 0° C 



1 



J1859 



965 

 17750 

 58 

 46 



16 



465 



560 

 7646 



736 



14 



497 



482 

 9489 

 8-3 

 644 



22 



396 



379 

 9720 



9-3 

 1012 



Rank J 



II. 1 



Rank f 



Mean path, tenth -metres 



Collisions in a second (millions) 



III. 1 



Mass, twenty-fifth grammes... 



A 



