II 



ATOMS AND MOLECULES 



Atoms Number of Divisions Numbers Weight Size Forms 

 Molecules Motions in Gases Effects of Heat Of Pressure 

 Diffusion Law of Numbers. 



I. Atoms The number of kinds. The number known 

 is constantly changing. It is now increasing, now dimin- 

 ishing. It has happened that a supposed element has 

 been broken up, and been proved to be not simple but 

 compound. New elements are also being discovered, as 

 in the case of argon. The number has been set down at 

 various figures not much under seventy. Is not this a 

 most impressive fact? Is it not a condition of matter 

 full of meaning? Considering the amount of it in the 

 universe and the number of particles at every point, is it 

 not an exceeding marvellous phenomenon that they are 

 all so ordered as to fall easily and perfectly into line 

 under about seventy divisions? There are not seventy 

 thousand, not seventy million, not seventy billion, but 

 seventy. Had they been vast in number, they would 

 have made a medley so multifarious as to be unworkable, 

 they would have rendered an ordered and compact system 

 of things an impossibility. It is not easy to reduce 

 ordered but mixed multitudes to their natural order. It 

 demands perception and attention, thought and care. 

 A housewife, with a large amount of goods and many 

 considerations of taste to determine, is ready to be almost 



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