Burette / Wet Mix Houses at M/S Factory Dalbeattie :
Following manufacture, the nitroglycerine would have had to be moved to the 'Wet Mix' or Burette Houses for mixing with
the nitrocellulose. The Burette Houses - technically 'House E' within the NG Hills - were here as in most places integrated
with the 'Wet MIx' Houses. A Burette House was originally the building where Nitroglycerine was added in controlled quantities
(burettage) to the Guncotton, before removal for hand or mechanical mixing ('Wet Mix') until the mix gelatinised as what
became known as 'Paste' or Modified Ballistite (blasting gelatine). This process was almost equally as dangerous as the
manufacture of nitroglycerine, as it was temperature sensitive and needed care to prevent the evolution of poisonous and
explosive fumes. Burettage and Wet Mix were in the same building as early as the 1900s, so although the technical name
remains 'Burette House', by 1939 the Dalbeattie structures were referred to by staff as 'Wet Mix'.
Separate lines of Burette Houses were eventually identified in both Unit 1 and Unit 2. Those in Unit 1 are along a
predominantly north-south axis from Culkiest down as far as the Knock Burn, whilst those in Unit 2 run northwest-southeast
from near the Edingham pillbox down into what is now the Edingham Industrial Estate. The Unit 2 Burette Houses were very
convenient for the nearby NG Hill, but the northern Burette Houses in Unit 1 were up to three quarters of a mile away from
the NG Hill in Unit 1. The writer suspects that some Burette Houses were left unfinished as being excess capacity, as Unit
2's NG Hills had only half the production capacity of Unit 1; nine rather than twelve Burette Houses would presumably then
have been adequate.
So far, no illustrations have been found of any Burette House operations that would match the features identified. The
structures found in field surveys and believed to be Burette Houses were termed 'Sunk Rectangular Enclosures' (SRE) and
initially were thought to be nitroglycerine batch-process units, until George Nicholson corrected this belief.
Burette/Wet Mix Process Information from various sources :
Evidence Deduced from Sanford's 1907 account of Nitrocellulose and Nitroglycerine Mixing :
The Sanford account of this in his 'Nitro Explosives' is of interest for several reasons :-
- The nitrocellulose was placed in double-walled lead-lined troughs or mixers, these being kept at a steady temperature
of 40° to 45° C by water circulating in the tank walls as the nitroglycerine was slowly added and carefully mixed
with the nitrocellulose. Acetone previously added to stabilise the nitroglycerine after Final Washing enhanced the
gelatinisation process and would make the cordite easier to work; more may have been added during the process.
- Sanford describes the use of high-pressure steam injected into tanks of cold water as the way to ensure a reliable
60° to 80° Centigrade hot water supply. This would appear to have been the system used at Dalbeattie, judging
from the arrangement of pipe bearers and tank bases at the entrance of the Burette Houses; the complexity of the tank bases
may indicate recirculation of the cooling water.
Just how the mixing took place is not clear, but there is evidence that cordite at Powfoot and Ardeer was blended by
powered stirrers a bit like commercial bread dough mixers, in a very wet environment to guard against acid fumes and fires.
The alternative was to use a wooden paddle to stir this 'Devil's Porridge', another 1914-1918 war expedient. The process
took about half an hour to complete, until the mix became semi-transparent and the nitrocellulose had been completely
dissolved. This appears to have been a different process to Incorporation, which reduced the gelatine paste to a dough-like
consistency; the writer has to admit that to have both 'Wet Mix' and Incorporation separately seems unusual, but the need
to maintain safety may explain this feature.
If powered stirrers were used, it is unclear how they were powered, although a shaft drive into the mixing house from an
external power unit might be involved. One solution to power and heating could have been a steam piston engine that
exhausted into the hot water system, but this seems a bit too exotic. It is suspected that electric motors were used.
The mixture would have been 65% guncotton, 30% nitroglycerine and 5% vaseline for Cordite MD, the type using acetone
in its production. Later in 1943, solventless cordite processes using ether-based guncotton collodion became available but
do not appear to have been carried out at Dalbeattie.
Archaeological Evidence at the Sunk Rectangular Enclosures and their Interpretation :
Identifying the structures used in this process was one of the hardest tasks the writer faced, for there were no definite
descriptions of the structure and process available other than 1907 descriptions of Nobel's works at Ardeer, the 1907
Sanford's 'Nitro Explosives' book and the 1916 account of processes in making 'The Devil's Porridge'. Descriptions
and pictures from Royal Navy Cordite Factory Holton Heath were similarly vague. The structures that seemed most suitable
(termed during the survey Sunk Rectangular Enclosures - SRE) were identified on the following basis :-
- Most SRE were within 200 yards of the Nitration Hills.
- Half of each SRE was surfaced in acid resistant gritless asphalt (ARGA), in common with other acid and explosive
handling areas. In the best preserved examples in Unit 1 there was a gridwork of slots, presumably for supports to tankage
or for drainage.
- There are a series of concrete bases - four with cast in place bolt studs - and two pipe supports, at the short
side between the two tunnel entries.
- Each SRE had tunnel entries through its surrounding bund bank or traverse, appropriate for narrow gauge
railway for explosives trolleys.
- Pipe supports approached each SRE, appropriate for delivery of required water and superheated steam.
- Unlike most nitration units of this period, the embankment heights indicated a simple one-storey structure.
- A large concrete tank with a sump was fitted in the end of each SRE most distant from the entrances. This may have been
a cooling pond or a drowning tank. The function of this enigmatic structure proved very hard to define.
- Wartime air photographs show that the asphalted area was indeed enclosed in a roofed house, but other features were
apparently in the open.
The evidence indicated that SRE were either an early type of batch-process nitroglycerine nitration house, a structure
for picrite nitration or (the most likely choice) burette houses for mixing nitrocellulose and nitroglycerine into blasting
jelly (Modified Ballistite) before its milling into cordite.
The Function of the Concrete Tanks :
This has to be inferred from position and surviving archaeology. The sump implies that they could be drained down through
a two-inch pipe, a slow process. The width and length - and the absence of any acid resistant lining - implies that water was
contained within them. A lead or rubber lining would have left signs of its presence in the form of fastening marks. That
left only a few functions :-
- Drowning Water Tank : For rapid immersion of people or substances subject to strong acids in a crisis where rapid
dilution or cooling was vital.
- Cooling Water Pond : Although only just below the presumed depth of the process tankage, a feasible place to dump
overheated water or to have a suitable heat-exchanger to cool water passing through in pipes.
No other process appeared feasible. Active nitration appeared unlikely as the tanks were not lined with lead or rubber,
so far as could be established from the dozen examples inspected. The feature called a 'labyrinth' used in early
batch-process nitration was considered and discarded due to this lack of a lining and the absence of an alternative
Burette Houses - Condition and Use :
Examination of the dozen SRE sites against one another has revealed some intriguing points about their site position
and construction. In each case, the writer has chosen to number the Burette Houses in Unit 1 from the north to south, and in
Unit 2 from northwest to southeast :-
Unit 1 Burette / Wet Mix Houses :
Unit 2 Burette / Wet Mix Houses :
- Unit 1 Burette 1 : Site low-lying and effectively overgrown marshland. If as badly drained in 1940, doubtful whether it
would have been operationally viable.
- Unit 1 Burettes 2 and 3 : Currently overgrown but dry and complete.
- Unit 1 Burettes 4 and 5 : Clear of vegetation and with excellent views of their original layout.
- Unit 1 Burette 6 : Location so overgrown that it is impossible to reach the entries or the interior.
Wartime reconnaissance training photographs have revealed that all twelve Burettes were completed in 1941, but Unit 1
may have already been vulnerable to flooding, as a February 1943 low-angle shot shows that water was in the nearby cutting
used by the Narrow Gauge bogie railway.
- Unit 2 Burette 1 : Concrete tank full of rubble from excavation collapse.
- Unit 2 Burettes 2 and 3 : Layout visible and in as good condition as Unit 1 Burette 4.
- Unit 2 Burette 4 : Front wall and entries destroyed, asphalt floor and concrete tank visible.
- Unit 2 Burette 5 : Inside Edingham Industrial Estate. As Unit 2 Burette 4 but later structures built inside for a
- Unit 2 Burette 6 : Site cleared of embankment and structures. 'Shadow' of tank, asphalt floor slots and edges detected
by summer grass growth in current cattle feeding area. Believed to have been built on this site in place of a site between
present 3 and 4.
Conclusion and Summary of Processes :
The SRE structures were the Wet Mix units. Nitroglycerine mixed with acetone was brought across from the Nitration Wash
Hills in suitable trolley-mounted tanks, brought in through the tunnels. Similar trolleys would have brought in the damp
Nitrocellulose in waterproof bags from the Guncotton Expense Magazines. The nitroglycerine was gradually added to the
nitrocellulose in the lead-lined heated tanks and gently stirred over a half-hour period, until gelatinised.
This gelatinised 'Modified Ballistite' mix was then removed from the tanks and taken onwards to Expense Magazines (stores)
beside the Incorporation Houses.
Identification of the equipment used in the processes remains a problem. Visitors with technical knowledge are invited to
make comments using the link at the bottom of this page.