I am not sure about the foundry air furnace, but the objective in adopting
reverberatories for lead and copper smelting was to avoid the need to sue
scarce wood-based fuel.  Certainly at Coalbrookdale the fuel was coal not
wood.

Peter King
49, Stourbridge Road,
Hagley,
Stourbridge
West Midlands
DY9 0QS
01562-720368
[log in to unmask]


-----Original Message-----
From: Arch-Metals Group [mailto:[log in to unmask]]On Behalf Of
[log in to unmask]
Sent: 05 July 2008 18:26
To: [log in to unmask]
Subject: Re: Early Use of Coal in Foundries


Coal and wood appear to have been preferred to coke or charcoal
(respectively)
in reverberatory furnaces, because the former are "long-flame" fuels. Both
release volatile organic compounds (oils, tars, turpentine, etc) when
heated,
and as these ignite in a directed draft they form a long plume of burning
vapor. This transfers heat quite efficiently from the fuel chamber to the
roof
of the chamber containing the metal to be melted. Radiation from the hot
roof
then heats the metal.

--
David Killick


Quoting Peter King <[log in to unmask]>:

> In a reverberatory furnace, the fuel and metal are kept separate so that
> there is no reason not to use coal.  The furnace is naturally aspirated,
by
> convection in a tall chimney, so that no power is needed.  It was an air
> furnace, as opposed to a blast furnace.  My guess is that Spotswood had a
> double air furnace, because he wanted to produce a lot of cast iron goods,
> rather than large-sized cast iron goods.  The Coalbrookdale Company had
> three in 1718-38, probably in different buildings, but only had one in
> constant use.  A second was used when a blast furnace was out of blast,
and
> the third hardly at all after the first few years of the period.
>
> Peter King
> 49, Stourbridge Road,
> Hagley,
> Stourbridge
> West Midlands
> DY9 0QS
> 01562-720368
> [log in to unmask]
>
>
> -----Original Message-----
> From: Arch-Metals Group [mailto:[log in to unmask]]On Behalf Of
> James Brothers
> Sent: 05 July 2008 17:20
> To: [log in to unmask]
> Subject: Re: Early Use of Coal in Foundries
>
>
> I would have thought that it would be impossible, or at least
> unlikely, to build a foundry in an urban setting until steam power was
> available. Also as you stated earlier the demand for cast iron objects
> was just too low to justify it. My specific concern is with what was
> going on on the west of the Atlantic. Coke was adopted much earlier in
> Britain, because the Americas were covered in forest. so getting
> charcoal was not a problem.
>
> The other early American foundry I am aware of is to the west of
> Richmond, VA at Westham. Its purpose was to make cannon for the
> Continental Army. Not sure what it used for fuel and a 19th century
> coke furnace was constructed on the same site which makes it difficult.
>
> On Jul 5, 2008, at 5:12 AM, Peter King wrote:
>
>> See also my earlier reply
>>
>> William Wood's efforts produced something that he called raw iron.
>> Even
>> when forged this was black on the facture and brittle.  It was
>> supposed to
>> be bar iron, but (at best) was usually poor quality, though there
>> were some
>> testimonies that it was alright.  I was looking at original
>> documents on
>> this yesterday and hope to deal with this in an article in due course;
>> suffice it to say that this is irrelevant to the subject under
>> discussion.
>>
>> There were air furnaces at Coalbrookdale for foundry work by 1718,
>> and these
>> certainly used coal as fuel.  This would be for heat only as there
>> is no
>> contact between fuel and metal in such a furnace.
>>
>> I have little doubt that canals would have been used to transport
>> charcoal
>> if there was a canal available, but the canal era in Britain only
>> began as
>> the charcoal era was (for the most part) ending.  My impression is
>> that
>> charcoal was usually gathered within a radius of about 5 miles for an
>> ironworks, but the limitation was more the cost of transport than
>> friability: See G. Hammersley in Economic History Review c.1973.
>> Examples
>> can be found of it coming from further afield.  I can think of one
>> case in
>> Shropshire of a charcoal purchase that might have been carried on
>> the river
>> Severn in the 1670s, but this would only work if there was a
>> convenient
>> navigable river; and they were few in number.
>>
>> There was a foundry in London in the 1700s, where the usual domestic
>> fuel
>> was coal.  Abraham Darby had one at Bristol in the same decade.
>> However,
>> urban foundries were scarce in this period.  They did not become
>> prevalent
>> until end of 18C or early 19C.  These probably had small foundry
>> cupolas,
>> but I am not clear how they were blown.
>>
>> Peter King
>> 49, Stourbridge Road,
>> Hagley,
>> Stourbridge
>> West Midlands
>> DY9 0QS
>> 01562-720368
>> [log in to unmask]
>>
>>
>> -----Original Message-----
>> From: Arch-Metals Group [mailto:[log in to unmask]]On Behalf
>> Of
>> James Brothers
>> Sent: 04 July 2008 18:30
>> To: [log in to unmask]
>> Subject: Early Use of Coal in Foundries