A few points in response to William Conner's posting:

I believe that the point that Martha Goodway was making referred to the age of the forests being harvested in the United States into the 19th century A.D.. Carbon-14 accumulates during the life span of an organic organism and the dating methodology will, of necessity, reflect this. You are not dating as to when the charcoal was made, but rather when the tree had significant levels of C-14 in its early life. This, I believe was the point that Martha was making.

There have been significant refinements in the application, methodology, and interpretation of C-14 since 1969. I am sure that many others on the list can articulate those issues better than I.

As to the use of green wood in an actual furnace itself I think that makes an already difficult metallurgical process almost impossible to achieve. The use of green wood, it seems to me, was probably in the charcoal making process itself and quite distinct from the operation of the furnace. Copice harvesting in the management of forest resources is an excellent example of this. In iron smelting you require reduction, high temperatures, and a light fuel source so that gasses (notably CO) will readily filter through the charge.

As to those Ohio Pit furnaces. I recently saw a presentation on them by a colleague of Mr. Conner at the Iron Masters meeting. Yes, they represent some sort of pryo-technological process. However, I remain unconvinced that they represent bloomery furnaces. The presence of green "slag" on red bricks means nothing. Those are common brick artifacts also found in pottery kilns, glass furnaces, and brick kiln remains - especially where salt was added to provide a glazing effect. The furnaces have a very broad diameter and are shallow, a brick air-slot comes into the very bottom of the pit and looks much more like an air vent for a kiln than a tuyere location in a furnace wall. These design features would inhibit direct-process ironmaking. The presence of bog ore in a fire-reddened pit means nothing. Bog ore had uses other than for iron making, notably in Colonial America for making iron-oxide slips for pottery. The same mistaken interpretation of a kiln for an iron furnace was made in the 1950's during the excavations of Jamestown Island, Virginia by the National Park Service. Slag is produced in many pryo-technological processes. Microscopic and petrological examination of specimens can be important evidence in identifying the process that created the slag.

Cheers!
Dave

David Harvey
Metals & Arms Conservator
Williamsburg, Virginia  USA

 



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