IISTTRODUOTION. 



ACCORDING to the most ancient view of the constitu- 

 tion of matter, the earth and all material things are but 

 modifications of one and the same original substance. 

 Fire, water, and air, were each in turn asserted to be 

 the primitive element, according to the arbitrary con- 

 jecture of philosophers who were bold enough to spec- 

 ulate upon the subject. At a later date, the views of 

 all seemed to be harmonized in ascribing the same 

 dignity to the three contending elements, and including 

 earth among the original varieties of matter. Earth, 

 Air, Fire, and Water, were assumed to be the original 

 materials out of which all forms of matter are produced. 



Modern chemistry has dethroned each of these ele- 

 mental monarchs of the world, and distributed their 

 prerogatives among a larger number. Earth, air, and 

 water, are all excluded from the list of elements, and 



