at Weirquay, in the parish of Bere Ferrers, Devon.
Including its relationship to the adjacent Union Tin Smelter.
Including its relationship to the adjacent Union Tin Smelter.
This lead/silver smelter is at NGR SX 433650, on the Devon bank of the River Tamar, three kilometres north-west of Bere Ferrers parish church. It lies between the road from Weirquay north-west to Hole's Hole and that running north-east to Gullytown. The smelter perimeter wall has a frontage of approximately 300 metres on the Gullytown road, broken by an entry into the eastern portion of the site now used as a habitation - Fern Cottage - and a west facing frontage of less than 100 metres on the Hole's Hole road. The west frontage is formed by the former offices - now a habitation called Treyard - and the main entrace gates into the smelter yard.
Adjoining the eastern end of the smelter site is the Union Tin Smelter.
A smelter appears to have been established on the site in the second decade of the 19th century by the Beeralstone Mining Company. In about 1836 Cornish interests were involved but by 1839 it was in the hands of Benjamin Somers, a lead smelter with interests on Mendip.
In 1845 the Tamar Silver-lead Mining Co. - operating very productive mines at South Hooe, a short distance upstream from Weirquay - purchased the smelter on the recommendation of Percival Norton Johnson a director of the company and leading metallurgist. Against a background of poor prices for silver-bearing ores it was intended that the smelter would process ores from the Tamar company's mine and other mines under the same management near Callington. A subsidiary company - the Tamar Smelting Co. - was established to operate the smelter which successfully treated the local ores and others regularly purchased from mines as far afield as Brittany (the Pont-Pean Mine, south of Rennes) and mid Wales.
During the 1850s the smelter employed at least four Cornish flowing (reverberatory) furnaces - two to three in work day and night at any one time - which required the ore to be calcined prior to smelting. At least six calcining furnaces were used in preparing the ore for smelting. Once smelted the silver-rich (fertile) lead was, prior to 1850, refined in cupellation hearths. There it was heated in a blast of air, converting the lead to litharge (lead oxide) which reacted with and absorbed other minor base metallic components. The litharge was drawn off, leaving metallic silver in the hearth, and then re-smelted to produce de-silvered (sterile) lead.
Refining using the cupellation method was time consuming and expensive in fuel and was generally confined to ores producing more than 8ozs of silver per ton. In fact one of the stated reasons for the acquisition of the smelter by the mining company was that purchasers of ores would only pay a premium on those producing more than 40ozs per ton, claiming the cost of cupellation as justification.
In 1849-50, on the recommendation of Johnson but against the wishes of a strong minority of shareholders who felt that the capital expenditure to be excessive, the Pattinson De-silvering Process was introduced at the smelter. This process utilised the fact that lead crystalises at a higher temperature than silver - by slowly lowering the temperature of a large pot of molten fertile lead to the point where the lead started to separate out as crystals and skimming them off, an enriched silver-lead was produced. The process was repeated a number of times in a series of pots until the lead content was reduced to a minimum and the residue was then subject to cupellation to produce pure silver.
Any lead rich slags - residues from the reverberatory furnaces - and some difficult refractory ores were treated in either a 'Welsh' blast furnace or a Scotch furnace. These, and the cupellation hearth, required a forced draught produced by bellows powered by steam engines, although a water wheel may have been used in the early years of the smelter - the draught for the reverberatory furnaces, including the calciners, was induced through the use of a tall chimney.
By the late 1840s the Union Smelter had been established on a site immediately to the east of the Tamar smelter, but this was treating tin ores and was initially operated as a separate concern.
The misgivings of some shareholders in the Tamar Silver-lead Mining Co. over the cost of installing the Pattinson Process eventually resulted in a decision to dispose of the Tamar Smelter and in late 1852 it was sold to the British and Colonial Smelting and Reduction Company, of which Johnson was a director, to be operated in conjunction with works at Millwall in London. This company continued to treat silver-rich lead ores, buying from the Tamar mines and elsewhere (including some Australian and South American ores) - operating a total of 20 furnaces and claiming to provide employment to 130 men and boys. However losses began to mount and in March 1855 it was decided to wind up the company.
Some dismantling of the furnaces took place on closure, probable to recover silver from the furnace bottoms - part of deficit of 20,000ozs between the assay of ores purchased and silver produced. The works then lay idle until 1864/5 when a new company - the Tamar Lead and Silver Smelting Co. Ltd. - was advertised to reopen both the Tamar and Union works. The works were at that time in poor condition. A report of 30 June 1864 lists the following plant on site -
A total of 18 furnaces, a de-silvering department in a very dilapidated state, and two steam engines.
The Tamar Lead and Silver Smelting Co. Ltd. was never registered as a limited company and it is currently unclear what work was carried out on the site after 1865. Some smelting activity may have been returned to the site and it is apparent that the two smelters, Tamar and Union, were considered as one unit after 1865 - the 25" OS map (1st edn.) of 1884 marks both under the name 'Tamar Smelting Works (Tin & Lead, disused)'.
The Union Works was subsequently used as a jam factory and the Tamar works converted to dwellings.
The importance of the Tamar Smelter is in the survival of a range of features relating to the operation of reverberatory furnaces for smelting silver-rich lead ores and the associated refining processes along with their infrastructure within a compact site. As David Cranstone, contractor to English Heritage, observed in his submission in respect of the Monument Protection Programme (Lead and Silver) dated 24 April 1991 -
'The two smelting works (Tamar with Union) at Weirquay are also of considerable national importance, since these sites plus Snailbeach New Cupola (Shropshire) are the three best survivals of reverberatory smelters in England, and the survival of the complete outline of the two adjacent complexes is unique.'
Whilst we are here concerned with that part of the site connected with the smelting and refining of silver-rich lead ores, the Union Works - primarily a tin smelter - at the eastern end of the site was operated in conjunction with the Tamar Smelter by at least 1865. (See illustration on the Tamar Lead and Silver Smelting Co. Ltd. prospectus - Guildhall Library, Stock Exchange Papers - showing the view of the site, including Union, from the east.)
The site is best divided into sections when describing the archeological potential (see diagram above, based on 1:2500 OS map of 1884) -
The Union Smelter is a listed building and therefore well protected under current legislation. The site as a whole lies within a Conservation Area which should protect the surviving structures from deliberate damage. However, recently (c. 1998), a Building Preservation Notice was placed on the western inhabited portion of the lead/silver smelter when there was the possiblity that a new entrance would made in the perimeter wall, exploiting a loophole in Conservation Area status.
It is hoped that a higher level of protection will be afforded to the smelter site in the near future.