Africa Trade
Saltford Brass Mill Project
Copyright (C) 2020 Saltford Brass Mill Project. All Rights Reserved
Registered Charity Number

Scheduled Monument        

Grade II* Listed Building 


The Bristol based brass industry was at the heart of advances in metallurgy in the 1700s, the processes being employed for the production of brassware comprising: copper smelting; calcining of calamine; alloying of copper and calamine to produce brass; distillation of zinc from calamine; production of brass by speltering; brass battery and rolling; and annealing of brass. 

Closely linked to this was the use of fuel, in particular developments which enabled the use of coal in preference to charcoal for the processing of metals. The scientific methods employed by the Bristol company were highlighted in the works of the Swedish scientist and philosopher, Emanuel Swedenborg, who described a laboratory at Baptist Mills in his book “Opera Philosophica et Mineralis” ("Philosophical and mineralogical works") published in 1734:

“A laboratory has been fitted up where they experiment on the different methods of converting copper into brass.  It contains a large number of assaying ovens and furnaces and the machinery works by flowing water.  There is a small hammer for testing how many blows the brass can endure without breaking; there are also teeth with which the brass is struck, but only once at any one point.”


Brass Alloying Cementation Furnace. Galon. 1749
Process of Brass Alloying by Cementation. Diderot. 1763

i.      The Art of Converting Red or Rosette Copper into Brass by means of Calamine Stone. Messes Galon & Duhamel Du Monceau,1749

ii.    L’Encyclopedie, ou Dictionnaire Raisonne des Sciences des Arts et des Metiers. Diderot and D’Alembert. 1763

iii.   The Bristol Brass industry: Furnace Structures and their Associated Remains, Joan Day, Journal of the Historical Metallurgical Society 22/1, 1988



Historical Metallurgy Society
Unfinished brass "shells" from Weston Mill
R F Tylecote - 1988
The Composition of Bristol Brass
D Hook and P T Craddock - 1988
The Bristol Brass Industry: Furnace Structures and their Associated Remains
Historical Metallurgical Society, 1988
Analysis of C18th Brass-Working Debris at Warmley
David Dungworth and Harriet White - 2007
Scientific Examination of Zinc-Distillation remains at Warmley
David Dungworth and Harriet White - 2007
Examination of Industrial Remains at Warmley
I C Freestone - 1988
Brass Manillas, Arm-Rings and Ankle-Rings

The collection of the Saltford Brass Mill Project includes three manillas, presumed to have been made in Britain, and three-arm rings / ankle-rings presumed to have been made in West Africa. 

Evidence suggests that two of the manillas were made by the Harford and Bristol Brass Company in the late 18th Century.  The third manilla is from the from the wreck of the schooner  Duoro, lost off the Scilly Isles in 1843, and presumed to have been made in Birmingham.

The two arm-rings and an ankle-ring are stylistically different to the manillas and are presumed to have been made in West Africa by recycling manillas or brass hollow-ware.   Evidence, however, links the rings to the Harford manillas; hence are assumed to be of similar date. 

In 2021, an opportunity arose to conduct a metallurgical analysis of the artefacts by the Deutsches Bergbau-Museum Bochum.  The analysis not only determined the composition of the material from which the artefacts were made but also included a comparison with a lead isotope tracing database.  The artefacts each contain a small proportion of lead which by use of the database enables their source to be identified.

This short paper at the link summarizes the background to the Saltford artefacts and the preliminary results of the metallurgical analysis.


Manillas tagged as being made by the Harford and Bristol Brass Company
Analysis of Manillas, Arm-Rings and Ankle-Ring
Anthony Coverdale & Tobias Showronek - 2021