Chap. 29.] [ 159 ] 



i 



C H A P. XXIX. 



I R O N. 



Exten/tve Utility of this Metal Its Properties. -Natural Hljlory of 

 Iron. Eagle- Stones. Blood-Stones. The Loa^ione. Emery. 

 Ochres. Smelting of Iron. Forging of Iron, Makittg of Steel. 

 tempering of Steel. C.i/f Steel. Great DiJ'pcfoion in Iron to unite 

 ivitb other Dotiics. -Green Vitriol, how procured. Prujjian Blue. 

 Ink. Inflammation of Sulphur and Iron. Tinning of Iron. Pre- 

 parations of Iron itjed in iMedicine. 



OF all metals, and I might perhaps be juftified in 

 adding, of all mineral fubftances, the mod gene* 

 rally ufeful is iron. To fpecify its ufes would be to 

 produce a catalogue of every thing that contributes to 

 the fullenance and the convenience of life. By the al- 

 ii ftance of this metal we till the land, and obtain the 

 fruits of the earth in greater abundance and perfection 

 than we could by any other means ; by irs agency we 

 are enabled to penetrate the earth itfclf, and procure 

 whatever it contains that may be ufeful or ornamental 

 to man ; there is fcarcely a mechanical trade, which 

 could be conducted on the prefent principles without 

 its aid, and many of them could not even exift were we 

 deprived of it : even in domeftic life our fafety, our 

 comfort, and our pleafure, all fsem in fome meafure 

 to depend on this moft valuable production of the 

 earth. As the quantity of this, as well as of fome 

 other minerals, which appear almoit necelFary to focial 

 exiftence, mud be limited, I have often thought that the 

 want of a fufficient fupply, which, on the fuppofition of 

 the prefent fyitem of things being continued forever, 

 mult at fome time neceflarily take place, forms a forcible 



argument 



