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it seems to be a sort of imperfect metal, generated of 

 two different seeds, that of silver and that of lead, 

 which makes it a kind of compound of both. And 

 it is sometimes found in silver mines, sometimes in 

 lead mines, though it has also mines of its own. It 

 is the lightest of all metals, very little ductile or 

 elastic, but the most fusible of all. It is scarce dis- 

 solvable with acids, but easily mixes with other metals. 

 Of all the substances concurring to form the terres- 

 trial globe, iron seems to have the greatest share ; as 

 it not only abounds in most kinds of stone, but enters 

 greatly into the composition of clay. This may be 

 judged from the similitude of colour between clay, 

 and dry iron-ore, from the easy vitrification of clay, 

 from the resemblance of vitrified clay ^ to clinkers of 

 iron 1 , from its deep red colour after calcination, and 

 lastly, from its yielding pure iron, by being burnt 

 with oil. 



Dr. Lister has shewn that sfones out of the human 

 bladder being calcined, iron may be extracted from 

 them by a loadstone. And there is scarce any terres- 

 trial substance either in men, brutes, or plants, which 

 after burning doth not exhibit some metallic particles. 

 Dr. Bucher says, that out of brick, earth, mixed with 

 any fat or oil, and calcined in the lire, he hath produ- 

 ced iron : for it is only the iron that causes the redness 

 of the bricks : and it can be extracted from them 

 again. Moreover, metals- are dissolved by the salts 

 and moisture in the earth, and so mix with the nutri- 

 cious juices of vegetables ; hence it may in some re- 

 spects be said, that we eat metals with the greatest part 

 of our food. 



The Arbor Martis is a germination of iron, resem- 

 bling a natural plant. The manner of its discovery 

 was this. One poured oil of tartar on iron filings, 

 dissolved in spirit of nitre in a, glass. Presently the 

 liquor swelled much, though with little fermentation, 

 and was no sooner at rest, than there arose a sort of 

 branches adhering to the glass^ which increased till 



