IRON. 
not affected by the different kinds of char- 
coal made irsejof. He remarks, neverthe- 
less, that it may be advisable to add from 
one-fourth to one-third of wood ashes, espe- 
cially where the iron is not of so good a 
quality as to afford steel possessing tenacity 
of body, as well as hardness. These ashes, 
which he used with success, prevent the 
steel-making process from being effected as 
rapidly as it would otherwise be, and give 
the steel pliability without diminishing its 
hardness. It is remarked, that in the case 
of this management, the blisters on the sur- 
face of the steel are smaller and more 
numerous. He likewise tried sea-salt. Fifty 
pounds of salt are sufficient for a furnace of 
steel of twelve thousand weight. The salt 
is pulverized, and sprinkled on the bars of 
iron when put into the furnace. He found 
that this ingredient likewise contributes to 
give body to the steel. In the arrangement 
of the bars in the furnace, the cement is laid 
one inch thick at the bottom, and half an 
inch thick between each layer of iron. 
Our author affirms, that the process would 
succeed equally well if the thickness were 
a little more than a quarter of an inch. The 
thickness of the bars of iron is indifferent, 
but there ought not to be a great difference 
in this respect between bars cemented at 
the same time. The common thickness is 
a little more than half an inch. It is not 
advisable that they should be very broad 
in proportion to the thickness, as this figure 
is found to produce flaws and cracks in the 
direction of the length of the bar. The 
bars may be square, or their breadth may 
cohveniently be somewhat more than twice 
their thickness. The fire for cementatioh 
must be of considerable intensity, and kept 
up until the conversion has perfectly taken 
place, which is ascertained by proof bars, 
so disposed as to be taken out from time to 
time. The cementation is finished on the 
sixth day ; that is to say, it commonly lasts 
five times four-and-twenty hours. And ac- 
cordingly, the workmen take one of the 
proofs out on the fifth day, which is forged, 
hardened, and examined by the fracture. If it 
break short, and show no indications of iron, 
the fire of the furnace is suffered to go out. 
But if it contain iron, the fire is kept up for 
twelve or twenty-four hours, accordingly as 
the quantity of fibrous iron may have prov- 
ed greater or less in the first proof. A 
second proof bar taken out at the proper 
time serves to direct them in the same man- 
ner with regard to their operations. By 
this management the cementation is conti- 
nued somewhat beyond the time requisite for 
the entire conversion. For there is less incon- 
venience attending a slight degree of excess 
in the cementation, than would result from 
a portion of iron remaining in the steel. 
The charcoal after cementation is as black, 
and apparently in the same state, as it was 
before. M. Duhamel moistened it, and 
applied it to the same use a second time : 
it apswered the purpose, but so much more 
slowly that he objects to the use of it in 
manufactories. From this, as well as other 
circumstances attending the steel-making 
process, it seems advantageous, at least 
with regard to expedition, that the coals 
should contain volatile matter. And hence 
the superior advantages of animal coal, such 
as the coal of leather, or the hoofs and horns 
of animals, imperfectly burned, which are 
used in case-hardening, though they may be 
less applicable to the longer process of steel- 
making for various reasons. 
M. Duhamel advises to have two tilting 
hammers ; one of the weight of one hun- 
dred and fifty pounds, and the other half 
that weight ; the first for the purpose of 
forging large works, and the latter small 
bars for cutlers. He recommends another 
small hammer of about twelve pounds for 
forging bars still smaller, to make gravers, 
small files, and the like. The steel must not 
be heated beyond the degree of cherry-red 
for forging. The tilting hammers should give 
at least three hundred stroke's in a minute. 
The cast steel of England is made as fol- 
lows ; a crucible about ten inches high, and 
seven in diameter, is filled with ends and 
fragments of the crude steel of the manu- 
factories, and the filings or fragments of 
steel works. They add a flux, the compo- 
nent parts of which are usually concealed. 
It is probable, however, that the success 
does not much depend upon this flux, 
which, from the quality of the cast steel 
itself, may be presumed to be of the nature 
of a steel cement. This crucible is placed 
in a wind'furnace like that of the founders, 
but smaller, because intended to contain 
one pot only. It is likewise surmounted by 
a cover and chimney to increase the draught 
of air. The furnace is entirely filled with 
coke or charred pit-coal. Five hours are 
required for the perfect fusion of the steel. 
It is then poured into long square, or octa- 
gonal moulds, eacli composed of two pieces 
of cast iron fitted together. The ingots, 
when taken out of the moulds, have the ap- 
pearance of cast iron. It is then forged in the 
same manner as other steel, but with less 
