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Summary

Early 20th century arsenic works at Wheal Anna Maria in the Devon Great Consols mine.

Location

Protected Status

• Scheduled Monument 1020328: Early 20th century arsenic works at the Devon Great Consols Mine
• Listed Building (II) 1326268: ARSENIC WORKS, FLUES AND CHIMNEY

Other References/Statuses

• National Monuments Record: SX47SW30
• Old DCC SMR Ref: SX47SW/504/5/3
• Old Listed Building Ref (II): 94052
• Old SAM Ref: 15559

Monument Type(s) and Dates

• ARSENIC WORKS (XX - 1901 AD to 2000 AD (Between))

Full description

Unknown, 1920s Arsenic Works at Devon Great Consols (Plan - sketch). SDV358821.

National Monuments Record, SX47SW30 (National Monuments Record Database). SDV220886.

Department of Environment, 1987, Gulworthy, 101c (List of Blds of Arch or Historic Interest). SDV220874.

Arsenic works comprising 3 calciners, grinding mill and engine house, flues and baffle chamber, further flue leading to inspection chamber and chimney to north. Devon Great Consols opened in 1844; all existing buildings were built in 1922. Slatestone and granite rubble with brick quoins to calciners and brick dressings. Calciners, grinding mill and engine house at lower level, zig-zag flues lead up to baffle chamber, further flue to north to inspection chamber and chimney. Engine house to east has large granite block platform, probably formerly had tramway leading to it from south; adjacent grinding mill has one grindstone (base) remaining on timber platform, hole at front of grindstone for crushed ore; remains of further building to east end, possibly originally calciner. Row of 3 calciners, each with pair of stoke holes to each side with brick segmental heads, lower stoke hole larger; splayed-back brick opening to former front opening at chamber height, to rear flues branched in zig-zag patterns about 10 metres uphill to baffle chamber. Flues diverted through as many channels as possible for maximum crystallisation of arsenic fumes. Baffle chamber has 8 round-arched openings to front and rear, 3 flue entries to west, each bay divided in 2 forming 16 vaulted internal chambers served by 2 flues; flues emerge to east, carried through long narrow passage about 100 metres, and merging into one flue, leading to inspection chamber below chimney, in rubble, cylindrical and tapered. Chambers and flue connected with the calcinus conform to specification dated 24th September 1866 in the lease for arsenic working. The flue to the stack should be at least 600 feet long. 'The section of the main chamber and first length of the flue being of the length of 90 feet shall be of 12 feet in height and 6 feet wide. A reduction shall be allowed after the first length of flue but no part shall be less than 4 1/2 feet by 3 feet wide. The walls of the chamber and flue shall be solidly built and the thickness of at least 2 1/2 feet of masonry where the flue is of the greatest dimension and nowhere less than 2 feet. The precipitation of the arsenic sulphur gases and volatile substances which pass beyond the main flues and chambers shall be effected by means of water falls and showers'. By 1870, half the world's supply of arsenic was produced here. Then the early 1920's Boll weevil epidemic in America led to the Duke of Bedford re-establishing the arsenic works as a philanthropic exercise in providing work locally. Other details: LBS No. 94052.

Pye, A. R. + Dixon, T.
Pye, A. R. + Dixon, t., 1989, An Archaeological Survey of the Arsenic Works and an Inventory of the Other Historic Workings at Devon Great Consols Mine, Tavistock Hamlets (Report - Survey). SDV226597.

Pye, A. R. + Dixon, T., 1989, The Arsenic Works at Devon Great Consols Mine, Tavistock,, 79-111 (Article in Serial). SDV219136.

Other details: Figs 1-5, Plates 1-10.

Egan, G., 1990, Post-Medieval Britain and Ireland in 1989, 198-200 (Article in Serial). SDV241563.

A survey of the 1921-25 arsenic works was carried out by Exeter Museums Archaeological Field Unit in 1989. The standing works were built between 1921 and 1923 and closed in 1925. The remains of most of the buildings survive. Ore was crushed, probably by steam-powered rollers, and dressed by water-powered jiggers (none of this plant survives). It was fed into calcining furnaces of which 3 types were present: two circular reverbatory furnaces, one rectangular reverbatory furnace and a bottle, or shaft, furnace. The arsenic gas was led along flues to a condenser with two sets of chambers for the collection of arsenic crystals. The crystals were refined in a further circular reverbatory furnace and collected in a separate condenser which has been demolished. The crystals were then milled and packed. Residual fumes were passed up a flue and into a 37 metre tall chimney. Other details: Plan.

Greeves, T. A. P., 1991, An Assessment of Copper Mining in Devon (Copper, Brass, Tin), 3, 14 (Report - Assessment). SDV60709.

Richardson, P. H. G., 1992, The Mines of Dartmoor and the Tamar Valley after 1913, 94-108 (Article in Serial). SDV323598.

After the cessation of work in 1903 there were periods of resurgence of mining for arsenic at Great Consols. In the 1920s a new arsenic works was constructed at Wheal Anna Maria, known as 'Devon Consols'.

Cranstone, D. + Hedley, I., 1995, Monuments Protection Programme: The Arsenic Industry, Step 3 Site Assessments (Report - Survey). SDV241572.

Site Number 1.
Devon Great Consols (SX 425 733).
Prime metal: Arsenic.
Description: Arsenic works, operative 1921-1925, within 19th century copper and arsenic mining complex. Preserves a wide range of calciners and condensing systems, all of masonry construction with brick linings.
Landscape: Within complex copper/arsenic mining landscape of Devon Great Consols, which is itself part of Tamar mining landscape.
Archaeology: Already surveyed: some stratigraphy, and residues of metallurgical interest.
Period: 1921-1925.
Assessment: One of the best surviving arsenic works nationally, preserving almost the full range of features. Large dressing waste tip to east should be included for group values.
Action: Delist and Schedule.
Management: Conservation of all masonry structure, and if feasible of timber grinding mill base, trestles and crusher base.

The arsenic works forms a self-contained unit of clear national importance. However, it lies in the midst of the very extensive remains of Devon Great Consols mine, successively the country’s greatest copper mine and the world’s largest arsenic producer. The 19th century mine was largely demolishes at Closure; there is an inventory of surviving field remains in Pye and Dixon 1989. On this evidence, the field remains appear to be too scattered and damaged for any sustainable Scheduled Ancient Monuments to be proposed. However, the landscape integrity of the site is intact, and the exposed bare waste tips contribute considerably to the character of the Tamar mining landscape. While large area scheduling is inappropriate, the site undoubtedly merits consideration in a Landscape Register context. In the interim, the following courses of action are suggested;

1)Notify the county archaeologist of the potential national importance of the whole complex, to ensure that archaeological implications of any development are fully considered.

2)Encourage any positive management proposals under schemes such as Country Stewardship or ESA designation.

Cranstone, D. + Hedley, I., 1995, Monuments Protection Programme: The Arsenic Industry: Introduction to Step 3 Site Assessments, 3, 4, 12, Site Number 1. (Report - non-specific). SDV357960.

Machine bed- Initially defined as a Tin Industry component. Crusher- No modification. Calciner shaft- No modification. Grinding mill- No modification. Refining furnace- No modification. Scrubber-The term has been substituted for waterfall, as being more widely used and less ambiguous.

Site Number 1.
Devon Great Consols (SX 425 733).
Definite national importance.

Dyer, M. J. + Manning, P. T., 1998, Objective 5B: Lower Tamar Valley Recreation and Land Management Iinitiative: Cultural Heritage Appraisal, 34 (Report - non-specific). SDV319814.

Buck, C., 1998, Preliminary Assessment of Sites of Archaelogical Importance in the Tamar Valley, 35 (Report - Assessment). SDV241750.

1920's arsenic refining works with long flue and stack 36 metres high.

Ancient Monuments, 2001, Untitled Source (Site Visit). SDV220880.

Early 20th century arsenic works at the Devon Great Consols Mine.

Buck, C., 2002, Devon Great Consols: Archaeological Assessment, 104,125-6,137-146+Fig 38 (Report - Assessment). SDV241758.

All the 1920's Arsenic Works buildings are Listed Buildings Grade II and designated as a Scheduled Monument. Features include the arsenic condenser at SX42577329, the reverberatory furnace at SX42577326, Brunton calciners at SX42577327 and SX42587328, refiner bed at SX42597329, grinding mill at SX42597330, the shaft kiln (bottle) furnace at SX42607332 and copper crusher, engine and boiler house plinths at SX42607330. Arsenic flues exist at SX42577328 from the calciners and furnace to the condenser and run from SX42587346 to the chimney at SX42587356 (see PRN 56083) with an arsenic waterfall chamber at SX42587346. The reservoir at SX42557331 was shown on the 19th century maps and provided water for the earlier Wheal Anna Maria dressing floor as well as the later 20th century arsenic works. Other 19th century features which were destroyed by the 20th century arsenic works at Wheal Anna Maria include a house or office at SX42607327, a waterwheel at SX42617330, three mine buildings at SX42587326, a small reservoir or settling pond at SX42587336 and most of a walled yard at SX42627328. Later features include a timber ore bin at SX42637327 and an iron water tank at SX42627323. Other details: Sites 132,168-9,191,192,195-207.

Department for Culture, Media and Sport, 2002, Early 20th Century Arsenic Works at the Devon Great Consols Mine (Schedule Document). SDV343971.

Early 20th century Arsenic Works at Wheal Anna Maria in the Devon Great Consols mine. The works occupies part of the site of a larger later 19th century arsenic works which was mostly demolished in 1903. The main processing area occupies two terraces with the crushing, calcining and refining structures on the lower terrace with flues rising to a condenser on the upper terrace. From the condenser a main flue extends over 250m north to the chimney (see PRN 56083). A 19th century rectangular reservoir 60 metres by 30 metres located to the north-west of the condenser fed water to dressing floor equipment, a water wheel & ore-separating equipment on the dressing floor to the north of the wheel. The north-eastern structure on the lower terrace is a bottle furnace with brick-lined openings for the two shaft furnaces. Flues link the furnace directly with the main flue to the west. Beams to the south-west supported an ore-crusher powered by a steam engine whose granite-capped rubble base survives with a base for the boiler. The arsenic mill reused an earlier two-floor rubble building refurbished in brick which has partly collapsed. The millstones remain on the reinforced first floor. South-west of the mill the arsenic refinery has collapsed leaving a dome of reddened brick with exposures of the circular furnace wall with a double entrance on the south side. Remains of a slate wall enclosing the refinery may derive from an earlier building. Other walls rebuilt in brick accommodate the refinery flues in the terrace retaining wall. Beyond the refinery two rubble-built square Brunton calciners survive almost to full height with brick quoins and arched openings to the power vaults and stoke holes. The power vaults retain their drive shafts pivoted on low brick plinths. A partly collapsed flat-bed reverberatory furnace occupies the southwest of the lower terrace with a flue rising to the condenser. The upper terrace is dominated by the calciner 28 metres long by 6 metres wide of slate rubble with brick quoins doorways and internal walling. The condenser is divided into two rows of vaulted chambers by an internal wall and baffle walls. Flues from the Brunto calciners and flat-bed furnace rise to two arched flue entries with iron shutter frames with further entries added later. Late in 1922 a second condenser serving the refinery was built to the north on the upper terrace but was later demolished. The main rubble walled flue 1 metre wide by 1.5 metres high with a brick vault runs 250 metres north from the original condenser with inspection doorways. At a point 95 metres south of the chimney the flue passes through a rectangular washing-tower chamber where residual arsenic was removed. The physical remains are complemented by the mine foreman's workbooks from 1921 to 1925. Other details: National Monument No. 155559.

Bodman, M., 2003, Watermills and Other Water-Powered Sites in Devon, 210 (Report - Interim). SDV325576.

Other details: Interim Draft Report.

Buck, C., 2009, Devon Great Consols Mine (Arsenic Works), Devon. Impact Assessment Report, 1-3, 13-27 (Report - Assessment). SDV347875.

Since closure, the site of the 1920s arsenic complex has gradually fallen into ruin, roofs have collapsed and some walls fallen down. The Tamar Valley Mining Heritage Project has proposed that a programme of building conservation and public safety works be undertaken, in order to enable access for the public, through a network of trails being created. The proposed scheme includes cleansing of surface arsenic contamination and building consolidation of the condenser, to allow members of the public to view the internal chambers through the existing openings in the south wall. Similar work is proposed for the two Brunton calciners, while it is recommended that a collapsed flue section of the hearth bed refiner is partially rebuilt. The shaft kiln furnace requires some repointing and some bricks around the openings will need to be re-bedded or replaced and re-mortared. No building conservation works are proposed for the arsenic grinding mill, and due to the fragility of the timber supports, public access is to be restricted by fencing the lower part of the site. A boardwalk will be constructed along the route between the condenser and other buildings, above the connecting flues, some of which are at ground level. This will separate people from possible surface arsenic contamination and minimise any detrimental effect on the archaeological resource. Other details: Figures 2, 4-9.

Department for Culture, Media and Sport, 2009, Scheduled Monument Consent Letter (Correspondence). SDV343970.

Scheduled Monument Consent granted, subject to conditions, in respect of proposed works concerning the conservation by means of consolidation and stabilisation of the various building remains, site safety works, access improvements, provision of site interpretation and safety signs and vegetation management.

English Heritage, 2011, Early 20th Century Arsenic Works at the Devon Great Consols Mine (Correspondence). SDV347712.

Scheduled monument consent granted, subject to conditions, for works concerning the reduction and rebating of opening grilles within the inner recess doorway opening, the alteration of the fenceline at the eastern end of the labyrinth and the exposure to a depth of 0.5 metres of feature and brick arch openings.

Sources / Further Reading

SDV219136	Article in Serial: Pye, A. R. + Dixon, T.. 1989. The Arsenic Works at Devon Great Consols Mine, Tavistock,. Proceedings of the Devon Archaeological Society. 47. Paperback Volume. 79-111.
SDV220874	List of Blds of Arch or Historic Interest: Department of Environment. 1987. Gulworthy. Historic Houses Register. Website. 101c.
SDV220880	Site Visit: Ancient Monuments. 2001. Unknown.
SDV220886	National Monuments Record Database: National Monuments Record. SX47SW30. National Monuments Record Index. Unknown.
SDV226597	Report - Survey: Pye, A. R. + Dixon, T. Pye, A. R. + Dixon, t.. 1989. An Archaeological Survey of the Arsenic Works and an Inventory of the Other Historic Workings at Devon Great Consols Mine, Tavistock Hamlets. Exeter Museums Archaeological Field Unit Report. 89.08. A4 Stapled + Digital.
SDV241563	Article in Serial: Egan, G.. 1990. Post-Medieval Britain and Ireland in 1989. Post-Medieval Archaeology. 24. Unknown. 198-200.
SDV241572	Report - Survey: Cranstone, D. + Hedley, I.. 1995. Monuments Protection Programme: The Arsenic Industry, Step 3 Site Assessments. English Heritage Report. A4 Bound.
SDV241750	Report - Assessment: Buck, C.. 1998. Preliminary Assessment of Sites of Archaelogical Importance in the Tamar Valley. Cornwall Archaeological Unit Report. A4 Bound. 35.
SDV241758	Report - Assessment: Buck, C.. 2002. Devon Great Consols: Archaeological Assessment. Cornwall Archaeological Unit Report. 2002R069. Digital + A4. 104,125-6,137-146+Fig 38.
	Linked documents:1
SDV319814	Report - non-specific: Dyer, M. J. + Manning, P. T.. 1998. Objective 5B: Lower Tamar Valley Recreation and Land Management Iinitiative: Cultural Heritage Appraisal. Exeter Archaeology Report. 98.60. A4 Stapled + Digital. 34.
SDV323598	Article in Serial: Richardson, P. H. G.. 1992. The Mines of Dartmoor and the Tamar Valley after 1913. British Mining. 44. A5 Paperback. 94-108.
SDV325576	Report - Interim: Bodman, M.. 2003. Watermills and Other Water-Powered Sites in Devon. A4 Spiral Bound. 210.
SDV343970	Correspondence: Department for Culture, Media and Sport. 2009. Scheduled Monument Consent Letter. Letter Regarding Proposed Works at Devon Great Consols Mine. Letter.
SDV343971	Schedule Document: Department for Culture, Media and Sport. 2002. Early 20th Century Arsenic Works at the Devon Great Consols Mine. The Schedule of Monuments. Letter. [Mapped feature: #89462 ]
SDV347712	Correspondence: English Heritage. 2011. Early 20th Century Arsenic Works at the Devon Great Consols Mine. Scheduled Monument Consent Letter. Letter.
SDV347875	Report - Assessment: Buck, C.. 2009. Devon Great Consols Mine (Arsenic Works), Devon. Impact Assessment Report. Historic Environment Projects, Cornwall Council Report. 2009R058. A4 Stapled + Digital. 1-3, 13-27.
SDV357960	Report - non-specific: Cranstone, D. + Hedley, I.. 1995. Monuments Protection Programme: The Arsenic Industry: Introduction to Step 3 Site Assessments. Monument Protection Programme. A4 Comb Bound + Digital. 3, 4, 12, Site Number 1..
SDV358821	Plan - sketch: Unknown. 1920s Arsenic Works at Devon Great Consols. Plan + Digital.
SDV60709	Report - Assessment: Greeves, T. A. P.. 1991. An Assessment of Copper Mining in Devon (Copper, Brass, Tin). A4 Stapled + Digital. 3, 14.

Associated Monuments

Associated Finds: none recorded

Associated Events

• EDV1447 - An Archaeological Survey of the Arsenic Works & other works at Devon Great Consols
• EDV1448 - Preliminary Assessment of Industrial Sites of Archaeological Importance in the Tamar Valley
• EDV1449 - Devon Great Consols: Archaeological Assessment
• EDV5334 - Impact Assessment of the Arsenic Works at Devon Great Consols Mine
• EDV896 - Preliminary Assessment of Sites of Archaeological Importance in the Tamar Valley
• EDV897 - Unnamed Event
• EDV5336 - Structural Appraisal of the Arsenic Works at Devon Great Consols Mine

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