1 82 ELECTRO-POLARIZATION OF ATOMS, 



the only test of the composition of the heavenly 

 bodies. The excitation of the flame of a blow- 

 pipe, directed upon specimens of metals and ores 

 laid on a piece of charcoal, affords a beautiful ex- 

 hibition of colors developed by different kinds of 

 molecules. The presence of molecules of stron- 

 tium, copper, soda, &c., modify the vibrations of 

 light and colors transmitted to the eye. 



FORMATION OF MOLECULES INTO CRYSTALS. 



The orderly and systematic movements of mol- 

 ecules during the process of crystallization are 

 wonderfully displayed by the magnifying powers 

 of optical instruments. Their shadow.y outlines 

 appear moving over a white sheet of canvas in 

 files, like drilled soldiers passing in review. The 

 gradual evaporation of a liquid solution of salts, 

 spread on a transparent sheet of glass, brings the 

 molecules toward each other within the range of 

 their reciprocal electro-magnetic forces ; when they 

 successively start forward to their proper places 

 to form beautiful symmetrical crystals, without any 

 of the jostlings or mistakes observable in the ranks 

 at a militia m.uster. So orderly are the movements, 

 that the molecules seem to be endowed with self- 

 motive and self-directive powers. Expressions of 

 surprise and admiration are often heard from 

 spectators, who for the first time behold the won- 

 derful automatic movements of molecules in the 

 process of crystallization. 



