Arsenic Works, Flues and Chimney

The Arsenic Works, comprising flues and a chimney, were built in 1922 on the site of the Devon Great Consols mine, which opened in 1844. The complex includes three calciners, a grinding mill, and an engine house, along with flues, a baffle chamber, an inspection chamber, and a chimney to the north. The buildings are constructed from slatestone and granite rubble, with brick quoins on the calciners and brick dressings.

The calciners, grinding mill, and engine house are situated at a lower level, and zig-zagging flues lead uphill to the baffle chamber. A further flue extends north to the inspection chamber before rising to the chimney. The engine house features a large granite block platform, likely formerly linked to a tramway from the south. Adjacent to the grinding mill is a remaining grindstone base on a timber platform, with a hole for crushed ore. Remains of a building, possibly a calciner, are found to the east.

The three calciners each feature a pair of stoke holes on each side, with brick segmental heads, the lower stoke hole being larger. A splayed-back brick opening is present at chamber height, formerly the front of the calciner. Behind the calciners, the flues branch in zig-zag patterns, ascending approximately 10 metres to the baffle chamber. This design maximized the exposure of arsenic fumes to encourage crystallization.

The baffle chamber has eight round-arched openings to the front and rear, with three flue entries to the west. These are divided into two bays, creating 16 vaulted internal chambers, each served by two flues. The flues emerge to the east, running through a long, narrow passage approximately 100 metres long, and eventually merging into a single flue leading to the inspection chamber below the chimney. The chimney itself is constructed from rubble, cylindrical, and tapered.

The design of the chambers and flue conforms to a specification dated September 24, 1866, relating to the lease for arsenic working, which stipulated a minimum flue length of 600 feet. The specification details chamber and flue dimensions, masonry thickness, and a system for precipitating arsenic gases using waterfalls and showers. By 1870, the works were producing half the world's supply of arsenic. Following an American boll weevil epidemic in the early 1920s, the Duke of Bedford re-established the works as a philanthropic project to provide local employment.