CLASS IV. 



INFLAMMABLES. 



INFLAMMATION, or combuftion, confifts in 

 the fixation and abforption of vital air by 

 combuftible bodies, and in the decompofition of 

 atmofpheric air by thefe bodies. As vital air is a 

 gas, and many combuftible bodies, by abforbing, 

 fix it, and make it take a folid form ; hence vital 

 air, when thus precipitated, will lofe the caloric 

 to which it owed it's elaftic fluidity ; and hence 

 comes that free caloric or heat, which is evolved 

 during combuftion. 



I. Aeriform. 



A. Hydrogen, 



Is one of the component principles of water ; 

 and in combination with caloric and light, forms 

 hydrogen gas. 



a. Pure Hydrogen^ exifts always in a ftate of 

 gas. It is a conftituent of water ; where it forms 

 one fixth. It is diftinguifhed from all other gafes, 



on 



