Gretna, Hm Factory, Eastriggs Explosives Factory, Acids Section, Denitration Plant

Canmore ID: 375020

NY26SW 38.28

NY 24968 64894 centred

What remains of these three structures are situated in dense deciduous scrub woodland some 15m to 25m WNW of the Storehouse for Nitroglycerine and Denitrated Acids (NY26SW 38.27). The more northerly structure (NY 24963 64905) is poorly preserved, but it is rectangular on plan and measures 26m from NNE to SSW by 11.5m transversely overall. There are a number of uprooted concrete footings for steel stanchions on the SSW, while on the E there is a shallow gully that seems to mark its limits. In addition, another five concrete footings for steel stanchions are situated within its foundations. Less than 2m from this structure’s SE corner there are the remains of a small building (NY 24971 64896), which is also rectangular on plan and measures 6m from WNW to ESE by 3m transversely. Its NW, NE and SW corners are marked by concrete footings for steel stanchions and these appear to be linked by brickwork as there are traces of this close to the NE corner. However, the structure itself also had a wooden component, as there are the remnants of at least one iron-sheathed wooden post within the interior on the SSW. The third structure (NY 24964 64881) is another building situated about 3m to the SSW. It is rectangular on plan and measures 20m from NNE to SSW by 15m transversely. A concrete floor rising 0.3m above the ground surface is delimited by four large concrete footings for steel stanchions on both the E and W respectively. However, the N and S sides are defined by two smaller concrete footings of which only the more easterly pair are positioned opposite one another. Three rows of seven smaller concrete footings running from NNE to SSW occupy the more westerly part of the building’s interior, beyond which is a pile of rubble. Immediately to the WNW of this rubble is a row of seven concrete footings for steel stanchions, which run the length of the building to the E of a narrow drain. An independent setting of four concrete footings ESE of the building is separated from it by a shallow gully. This is linked to a small rectangular feature delimiting a shallow hollow.

These three structures are identified as a Denitration Plant on the plan of, and in text refer-ring to, the works (MMW 1919, plan, 95-100, figure IVa) given in the report by the Ministry of Munitions of War outlining the processes involved in the manufacture of the cordite propellant during the First World War at H.M. Factory, Gretna (Site 3). The Denitrator plant was where Nitroglycerine spent acids were separated out into nitric acid and sulphuric acid for reuse elsewhere. The Nitroglycerine was piped from the adjacent Storehouse (NY26SW 38.27) to a Kestner blower which raised it to a tank house supported on a tall steel frame-work. The tank is represented by the four concrete footings on the ESE side of the southerly building referred to above, while the adjacent hollow to its ESE held the blower. The interi-or of the S building to the WNW of the tower contained the denitrators and the coolers on the ESE, while the Hartz condensers appear to have been supported on a steel framework constructed over the three rows of smaller concrete footings on the WNW side of the build-ing. After the two acids were separated, the sulphuric acid was returned to the Storehouse and thence to the Gaillard Towers (NY26SW 38.26). By contrast, the nitric acid was con-veyed to receiving tanks in a lean-to. This was situated on the WNW side of the southern denitrator building - the outer edge of which is represented by the row of seven concrete footings running adjacent to the narrow drain. From here the nitric acid was transferred by pipes to the Condenser Towers forming the heart of the more northerly structure (NY 24967 64906). These Towers were encased within a complicated steel framework represented by the uprooted concrete footings – all that now remains visible of this part of the plant. After the nitric acid was condensed, it was sent back to the Nitroglycerine and Denitrated Acids Storehouse (NY26SW 38.27) for re-distribution. An undated map (SUPP 10-39) held by the National Archives at Kew illustrates all three structures and the links between them. Blue-prints (SUPP 10-27, 3654, 3775; SUPP 10-28, 3882, 3938; SUPP 10-29, 4116), together with ground-based, contemporary official photographs (MUN 5-297 pt2, 315; MUN 5-297 pt3, 368, 453, 472) taken during and after construction also held at Kew show the character of these buildings. The tank house perched above a tall steel framework was initially con-structed on a rectangular plan. It was a single storey, Belfast roofed building clad with wooden planks. However, it was later reconstructed with a ridge roof capped by a vent running along its full length. The southern building was a tall, single storey, steel-framed, corrugated iron sheet clad structure, which was also provided with a Belfast roof. The clad-ding extended only part-way down the sides of the building leaving the lower section open to the elements. There were thirteen slit vents below the eaves in the NNE elevation, at least three horizontal windows in the WNW elevation and at least one rectangular window in the ESE elevation. The lean-to was of similar construction and had a roof that sloped downwards from ESE to WNW. It may have had at least three windows in the WNW elevation. The small building (NY 24976 64896) adjacent to the SE corner of the Condenser Towers was a fan house. This extracted the waste nitric acid fumes from the Condenser Towers and expelled them into the atmosphere. It was a single storey, brick-built, steel-framed structure with a ridged roof capped by a vent. There was a central window in the NNE ele-vation and another in at least one of the gable ends.

All three structures fell into lot 508, which was offered for sale by auction on 22-5 July 1924 (HM Treasury 1924, 101), when the lot was divided between J. M. Temple, Blackhills, Eastriggs and Messrs James Jackson & Co Ltd, St Vincent Street, Glasgow (Carlisle City Ar-chives, DX 2040/3). After their removal from the site what remained of the foundations were left in place. These are faintly visible on an aerial photograph (M124/13 04117) flown on 19 August 1940.

Visited by HES Heritage Recording (MMD and ATW), 11 May 2022.