EXACTITUDE OF POLARITY ESSENTIAL. 99 



III! 



therefore, they cannot combine with hydrogen for such purpose 

 till separated*. 



There is a circumstance respecting carbonic-acid gas, men- 

 tioned by Sir H. Davy, worthy of notice : that an electrical 

 machine, totally surrounded by this, gas, is capable of greater 

 excitement than when insulated in hydrogen gas. 



There is every reason to conclude that such should be the case 

 when obtaining positive electricity. 



Now carbonic-acid gas is (as well known) composed of 2 

 atoms of oxygen, and 1 atom of carbon. 



We shall submit for selection two hypothetical arrangements 

 of composition. 



1st. The positive poles of the two molecules of oxygen are 

 united to the negative pole of the one molecule of carbon. 



In this case the positive poles of oxygen are protected from 

 the polar attraction of hydrogen and nitrogen, in the order 

 essential to the formation of light. 



2nd. Let the positive pole of carbon be in contact with the 

 negative pole of one atom of oxygen, while it is at the same 

 time united by its negative pole to the other atom of oxygen. 



Can the carbon, with strict obedience to the law of electrical 

 attraction, occupy a central position, which would oblige the 



* The exactitude of polarity appears necessary, as its deficiency, or inter- 

 ruption, occasions the complete prevention of chemical union essential to the 

 transition of fixed matter to the radiant state, and causes combustion to be 

 immediately extinguished ; which is proved in the instance of water t as well 

 as carbonic-acid gas, and several other bodies similarly constituted, of inflam- 

 mables and supporters of combustion ; for instance, 



Hydrogen.] 



And oxygen in excess in gaseous mixtures of carburetled hydrogen. 



H 2 



