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POPULAR SCIENCE REVIEW. 
mottled, and white, we are well acquainted, and a good furnace- 
manager can determine, from known materials, the result which, 
shall he obtained. With all the mysteries of cinder-iron are we 
also familiar ; and it cannot but be regretted that there are 
manufacturers who study the art of sophistication so zealously 
as to produce a composition, still called iron, in which that metal 
occupies the minimum space. 
We started with the assertion that although iron had been so 
long known to mankind, we were still imperfectly acquainted 
with its physical and its chemical properties. We repeat this, 
and cannot refrain from expressing a hope, seeing that the 
experiments required would be too expensive for any man to 
undertake, that some associated iron-masters would select a 
skilful and reliable experimentalist, place a furnace at his dis- 
posal, and meet all the expenses of this fine inquiry. 
Crude pig-iron is a compound of iron and carbon, mixed with 
several substances. To produce wrought or malleable iron, a. large 
portion of the carbon is to be removed, and the impurities dis- 
sipated. The process is essentially one of oxidation. It is not 
possible to describe in detail the structure of the “refinery,” or 
oxidizing blast-hearth, nor to enter into the history of the process 
of “ puddling,” and discuss the several stages of the operation. 
It must suffice that we state, that the refining consists in placing 
about two tons of pig-iron upon a fire, lit in the centre of the 
refinery-hearth, covering it up with coke, and then urging the 
fire by a gradually-increasing blast until the iron is melted. It 
is kept in a perfectly liquid state under the influence of the 
blast for some time, the carbon combines with oxygen, and 
escapes as carbonic acid, while the adventitious metals are 
oxidized and volatilized. In the W elsh iron-works one ton 
of white iron takes from one and three quarters to two hours to 
refine, the consumption of coke being from six to eight cwt., 
and the loss of metal about three cwt. Instead of air, steam 
is often employed in the refinery process, and in general with the 
best possible result. In effect, the process is to blow the fire on 
the hearth, and act on the melted iron, with steam under a 
pressure of from 40 to 50 lb., and at a temperature of about 
700° Falir. We are informed that 396 cwt. of pig-iron pro- 
duces by this process 393 cwt. of refined metal. The saving 
here is great, and half an hour appears a sufficient period for 
refining a ton of crude pig-iron. Refining by gas has been 
introduced, and by some highly approved. The fine metal 
produced by the refining process is subjected to the process of 
“ puddling,” introduced in 1783 by Mr. Henry Cort. The pud- 
dling furnace is so constructed that the intensely-heated vapour 
or flame plays or reverberates upon the melted metal, and being 
brought to a bright red heat, about four or five cwt. of fine metal 
