12 INTRODUCTION. 



the hydrogen escapes, and is inflamed ; 

 and the only means, known to man, 

 for averting the calamity, serves but to 

 increase its destructive energy. Again : 

 if the heat evolved from a body (molt- 

 en metals, for example,) be sufficiently 

 intense, the oxygen will be expelled, 

 and will not again combine with it till 

 the temperature of the body be suf- 

 ficiently reduced to reproduce its affin- 

 ity for this gas. 



Had the gases, oxygen and hydrogen, 

 not existed, fire, air, (as now constitut- 

 ed,) and water, with all their depend- 

 ents, such as life, light, sound, &c., 

 would have been unknown ; and the 

 earth would have presented an appear- 

 ance like that of shining metals, brill- 

 iant to the eye, (had there been eyes 

 to see it,) but totally unfit for the hab- 



