NEW CONCEPTIONS IN SCIENCE 



the invisible molecular world, the chaos from 

 which all things come. 



Half a dozen distinct lines of investigation lead 

 to the calculation that these ultimate particles 

 cannot be larger than a very few micro-microns, nor 

 less than a twentieth or a thirtieth of a micro- 

 micron. These are the widest limits; there is good 

 reason for believing that the size of the mole- 

 cules varies only between a single micro-micron and 

 one-tenth of that. This is Lord Kelvin's estimate. 

 If Professor Rontgen's oil - films were, as he be- 

 lieves, continuous, then the upper limit for oil 

 molecules would be half a micro-micron, for that 

 was the estimated thickness of his films. Professor 

 O. E. Meyer, who has written an exhaustive work 

 on the subject, passes in review all the various 

 methods of computing the size of the molecule, 

 and concludes that their average diameter is not 

 far from two-tenths of a micro-micron (0.2 pp). 



Accepting Professor Meyer's estimate, the thin- 

 nest part of the soap - bubble is about thirty 

 molecules thick, Faraday's layers of gold-leaf about 

 twenty, and Professor Rontgen's oil-films two or 

 three. Of all the conquests of the human mind, 

 I know of none more beautiful than this, wherein 

 it has reached out into the invisible world, and, 

 so to speak, put upon the scale-pan the units of 

 creation, the stuff of which worlds are moulded. 



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