672 PHILOSOPHICAL TRANSACTIONS. [aNNO ISQS. 



the iron pieces, acting like a ferment to them, and making them tender. Let 

 the workman now take one of the pieces out of the fire, and put it under the 

 great hammer, to be drawn out into bars, and wrought ; and then, hot as it is, 

 plunge it into cold water. Thus tempered, let him again work it on the anvil, 

 and break it; and viewing the fragments, let him consider whether it look like 

 iron in any part of it, or be wholly condensed, and turned into steel. Then let 

 the pieces be all wrought into bars, which done, give a fresh blast to the mix- 

 ture, adding a little fresh matter to it, instead of that which had been drunk up 

 by the pieces of iron ; which will refresh and strengthen the remainder, and 

 make still purer the pieces of iron again put into the dish ; every which piece, 

 let him, as soon as it is red-hot, beat into a bar on the anvil, and cast it, hot as 

 it is, into cold water. And thus iron is made into steel, which is much harder 

 and whiter than iron."* 



There is but one place that I know of, which may give us any sight into the 

 inquiry concerning our tools, and that is in Pliny, lib. 34, c. 14, where speaking 

 of iron, he says, furnacum maxima differentia est : in iis equidem nucleus ferri 

 excoquitur nd indurandum aliter, alioque modo ad densandas incudes malleo- 

 rumve rostra. From this passage it should seem, that the ancients had one 

 way to make steel, and another way to harden or temper their tools, particularly 

 such at picks and anvils. It is also plain, that nucleus ferri was melted down 

 in both. Again, the difference was in the furnaces, that is, in the manner of 

 ordering the iron to be made into steel, or for the extraordinary hardening 

 of the heads and tips of tools, and not in the matter of which they were made, 

 for both were done by boiling them in molten iron. It cannot be doubted, but 

 by nucleus ferri must be meant well purged iron ; the same which Aristotle calls 

 it^yeia-jAivof iriv^Dfo? ; for why else should he tell us that wrought iron itself may 

 be made liquid, so as to harden again, that is, to cast again into sow-metal, if 

 it was not to explain to us the manner of making steel ; which they did probably 



• The processes for converting iron into steel are different in different countries, and in different 

 works in the same countries. In Sweden it is sometimes obtained, under particular management in 

 the fusion, directly from the iron-ore, and is then called ore-steel or natural steel ; but it is commonly 

 prepared either from cast-iron or forged iron ; the cast-iron being made to undergo certain changes in 

 furnaces constructed for the purpose, and the forged iron being subjected to the process of cemen- 

 tation. The steel made from forged iron is called cement-steel or blister-steel. This blister-steel, 

 being fused in a particular manner, yields what is termed cast-steel. See Mr. CoUier's paper, before 

 referred to, in the 5th vol. of the Manchester Memoirs. The change produced in the iron by all 

 these processes appears to be the same, varying only in degree, viz. a quantity of carbon is combined 

 with it. Further modifications in relation to its valuable qualities of hardness, elasticity, and suscep> 

 tibiliiy of fine polish, are effected by compression under the hammer, by immersion whilst red-hot in 

 cold water, or other cold liquid, and by annealing. 



