THE JOURNEYING ATOMS 



reached a world where perpetual motion is the rule; 

 we have reached the fountain-head of energy, and 

 the motion of one body is not at the expense of the 

 motion of some other body, but is a part of the spon- 

 taneous struggling and jostling and vibration that 

 go on forever in all the matter of the universe. What 

 is called the Brunonian movement (first discov- 

 ered by the botanist Robert Brown in 1827) is 

 within reach of the eye armed with a high-power 

 microscope. Look into any liquid that holds in sus- 

 pension very small particles of solid matter, such 

 as dust particles in the air, or the granules of ordi- 

 nary water-color paints dissolved in water: not a 

 single one of the particles is at rest; they are all mys- 

 teriously agitated; they jump hither and thither; 

 it is a wild chaotic whirl and dance of minute par- 

 ticles. Brown at first thought they were alive, but 

 they were only non-living particles dancing to the 

 same tune which probably sets suns and systems 

 whirling in the heavens. Ramsay says that tobacco 

 smoke confined in the small flat chamber formed in 

 the slide of a microscope, shows this movement, in 

 appearance like the flight of minute butterflies. 

 The Brunonian movement is now believed to be due 

 to the bombardment of the particles by the mole- 

 cules of the liquid or gas in which they are suspended. 

 The smaller the particles, the livelier they are. These 

 particles themselves are made up of a vast num- 

 ber of molecules, among which the same movement 



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