HP^^w 



144 CARBON. I 



ness a piece of wood closely covered with sand in a crucible,- 

 so as to preserve it while ' in the fire, and afterwards, while] 

 cooling, from the action of the atmosphere. It is capable ofj 

 forming various combinations, but charcoal is that witll 

 which we are most familiar. Carbon is not only a compo*^ 

 nent part, but it forms nearly the whole of the solid basis ofl 

 all vegetables, from the most delicate flower in the garden to' 

 the huge oak of the forest. It not only constitutes the basis- 

 of the woody fibre, but is a component part of sugar, and of i 

 all kinds of wax, oils, gums, and resins, and of these again,^ 

 how great is the variety ! It is imagined that most of the, 

 metals may be combined with carbon ; but at present wej 

 know only of its combination with iron. In one proportior* 

 it forms cast iron ; in another, steel ; and in a third, plum^ 

 bago, generally, though improperly, called black lead. Ther0t 

 is no lead in its composition. Cast iron contains about onrf 

 forty-fifth of its weight of carbon, — steel is combined witM 

 about one part of carbon in two hundred of iron, — and plumJ 

 bago, or carburet of iron, has been found to consist of nearly^ 

 nine parts of carbon to one of iron. Wrought iron differa 

 from cast iron, in being deprived of its carbon and oxygei^ 

 by continued heat and repeated hammering, which render 

 the metal malleable. Steel is made of wrought iron by va* 

 rious processes, whereby the metal resumes a small portion^ 

 of the carbon, and acquires a capacity of receiving different 

 degrees of hardness. { 



The metals are generally procured from beneath the surl 

 face of the earth, in a state of combination either with othe| 

 metals, with sulphur, oxygen, or with acids ; though a fev|r 

 of them have occasionally been found in a state of purity^ 

 Metals are the great agents by which we are enabled ti 

 examine the recesses of nature ; and their uses are so mul^j 

 tiplied, that they are become of the greatest importance ir 

 every occupation of life. They are the instruments of al 

 our improvements, of civilization itself, and are even sub 

 servient to the progress of the human mind towards perfec 

 lion. They differ so much from each other, that natur I 

 seems to have had in view all the necessities of man, in oi 

 der that she might suit every possible purpose his ingenuit 

 can invent, or his wants require. We not only receive th; ' 

 great variety from the hand of nature, but these metals ai 

 rendered infinitely valuable by various other properties th< 



