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iron produced, and also in reference to the yield, as it is 
termed, or the quantity of finished iron produced from a 
given quantity of pigs : this will vary much according to the 
quality of pigs used, form of furnace, character of fuel, and 
skill of workmen. It is now generally considered that 
22 cwt. of pig iron is required to make 20 cwt. of puddled 
bars, and about 21icwts. of puddled bars to make 20 cwt. 
of the finished merchant iron. Some idea of the improve- 
ments effected in this department of the manufacture may be 
formed from the fact, that when the system of puddling was 
first introduced, 33 cwt. was required to produce the same 
quantity of merchant iron now made from 24 cwt. of pigs. 
The peculiarities or properties to which I wish further to 
advert, are body, soundness, clearness, toughness, hardness, 
and softness. 
First, as to body. This term is applied both to iron and 
steel in a very loose and indefinite manner, but I believe is 
usually meant to imply the property of bearing considerable 
and repeated action of fire without becoming brittle. It is a 
most mysterious property, and chemistry has not yet been 
able to inform us on what conditions this property depends. 
The manufacturer of bar iron knows, however, that it exists 
in some kinds of pig iron more than in others ; that it exists 
less in hot blast than in cold blast pig iron, and least of all 
in those pigs in the manufacture of which any considerable 
quantity of silicate of iron, termed cinder, the refuse of the 
forges, has been used. It is one of the most essential parts 
of the education of a skilful iron master, to learn what mix- 
ture of pig iron of various kinds he can most economically 
use, to produce precisely the sort of iron which he requires 
for special purposes. At my brother's and my works, at 
Leabrook, Tipton, where we employ twenty-two puddling fur- 
naces in making only special kinds of iron, there are fre- 
quently many adjoining furnaces, each with a different assort- 
