Acid Tar Lagoon

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Hoole has a remarkable "Acid Tar Lagoon". The lagoon arose as a result of over 62000 tonnes of liquid acid tar waste from benzole refining being poured into the excavated clay pit of a brickworks until sometime around 1967. This article looks at a history which starts with an English colony in Peru and ends in a field in Hoole. There are two companies mentioned in this story - National Benzole, which had nothing to do with the Acid Tar Lagoon in Hoole, but provides some background for the history of benzole: - and Lobitos, which has been idenified as the source of the Acid Tar in the lagoon at Hoole.


Benzole (often known as Benzol) is a noxious coal-tar derivative. It was once produced as a by-product of the manufacture of coke by heating coal in a closed retort. This drives off coal gas which was once used extensively for lighting as "Town Gas" - a process which is known as "destructive distillation" - and leaves behind coke. Town Gas contains hydrogen, carbon monoxide and flammable hydrocarbons. It has a characteristic smell due to some sulphur-containing impurities. The remaining coke was used for heating and in a variety of industrial processes, including steel-making.

Benzole was an early alternative to petrol/gasoline as a motor fuel which improved mileage and had anti-knock properties.

As well as gas and coke a "gas works" also produces coal tar, which has both medical and industrial uses. Coal tar was discovered circa 1665 and used for medical purposes as early as the 1800s. Circa 1850, the discovery that it could be used as the main ingredient in synthetic dyes engendered an entire industry. In the coal gas era, there were many companies in Britain whose business was to distill coal tar to separate the higher-value fractions, such as naphtha, creosote and pitch. Many industrial chemicals were first isolated from coal tar during this time, yet coal tar is a very complex mixture and many of its components, especially those present at low levels, remain unidentified. Some well-known pharmaceuticals, such as paracetamol, were first manufactured as coal-tar dervatives. When Arthur Conan Doyle wished to demonstrate the character of Sherlock Holmes in "The Adventure of the Empty House", he has him explore Tibet, visit Mecca, travel to Khartoum and then do research on coal tar derivatives in Montpellier: the implication being that all four were equally difficult.

Benzole is the term used in the UK for a coal-tar product consisting mainly of the aromatic hydrocarbon liquids benzene and toluene. It contains little of the various octane isomers which petrol is based on. Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma around petrol (gasoline) stations, although modern petrol actually contains very little of it (less than 1%). The word "benzene" derives from "gum benzoin" (benzoin resin), an aromatic resin known to European pharmacists and perfumers since the 16th century as a product of southeast Asia. Gum benzoin does not actually contain any appreciable level of benzene, but contains the related Benzoic acid. The hydrocarbon derived from gum benzoin thus acquired the name benzin, benzol, or benzene. Michael Faraday first isolated and identified benzene in 1825 from the oily residue derived from the production of illuminating gas, giving it the name "bicarburet of hydrogen". Toluene was first isolated in 1837 through a distillation of pine oil by the Polish chemist Filip Neriusz Walter, who named it rétinnaphte (resin naptha). In 1841, French chemist Henri Étienne Sainte-Claire Deville isolated a hydrocarbon from balsam of Tolu (an aromatic extract from the tropical Colombian tree Myroxylon balsamum), which Deville recognized as similar to Walter's rétinnaphte and to benzene; hence he called the new hydrocarbon benzoène. In 1843, Jöns Jacob Berzelius recommended the name toluin. In 1850, French chemist Auguste Cahours isolated from a distillate of wood a hydrocarbon which he recognized as similar to Deville's benzoène and which Cahours named toluène. In 1845, Charles Blachford Mansfield, working under August Wilhelm von Hofmann, isolated benzene from coal tar. Four years later, Mansfield began the first industrial-scale production of benzene, based on the coal-tar method. In the 19th and early 20th centuries, benzene was used as an after-shave lotion because of its pleasant smell. Prior to the 1920s, benzene was frequently used as an industrial solvent, especially for degreasing metal. As its toxicity became obvious, benzene was supplanted by other solvents, especially toluene, which has similar physical properties but is not as carcinogenic. In 1903, Ludwig Roselius popularized the use of benzene to decaffeinate coffee. Confusingly, in certain languages, such as German, Hungarian, Ukrainian and Russian the word "benzol" (or benzole) means benzene, and in some of these languages, words pronounced like benzene (e.g. the German word "Benzin") can mean petroleum or gasoline.

National Benzole used "Mr Mercury" in its advertising.

Benzole was also originally used as a "motor spirit", as were petroleum spirits and alcohol. Benzole was also blended with petrol and the combination sold as a motor fuel. Use of Benzole as a motor fuel was particularly prevalent in Germany after WW1 when the country was isolated from supplies of petroleum and needed a "synthetic" alternative. At the time most of Britain's coke ovens did not recover Benzole and the crude by-product was exported in an unrefined state, or the benzole was left in the gas as it improved luminosity. In normal benzoles produced by high-temperature coal-gas processes, the aromatic hydrocarbons may be assumed to be roughly in the proportion of 70% of benzene, 20% of toluene and 10% of the xylenes or solvent naphtha. Actually, the proportions in which the constituents are present vary considerably, depending on the character of the coal carbonised, the conditions of carbonisation, and subsequent processing. Benzole can be a fair or poor motor fuel depending on its composition, but it has the advantage that the addition of benzene to petrol increases the octane ratio and reduces knocking or pinking (pre-ignition). On the down-side engines begin to soot very quickly which results in a decrease of power and possible failures. The initiative in Britain for the creation of petrol stations as we know them today, came in November 1919 from the AA (the Automobile Association) in an attempt to help its members obtain not petrol but British-made benzole. Its sale was promoted as a cheaper alternative to Russian imported benzole and as a patriotic response to the repression and atrocities carried out by the Bolsheviks against their political opponents following the 1917 revolution. The station was intended for members' use only, and the AA made no profit on the fuel. The station, which was on the Bath Road (A4) near Aldermaston, had an underground tank, a Bowser pump inside the building, with the hose taken through the window, a compressor for inflating tyres, a fire extinguisher, and a toilet, described by Trevor Lord as "of bucket type, and seldom used". As the fuel tank was in a hole in the ground the stations were known as "replenishment pits". They established the modern pattern of vehicles pulling off the public road and drawing up alongside petrol pumps rather than being filled at the kerbside as at garages.

By 1927 National Benzole was a nationally established fuel brand in the UK, best known for its 50:50 blend of benzole and gasoline. Benzole, because it is a source of benzene and toluene, is also an important feedstock for the manufacture of many other chemicals such as dyestuffs and explosives. In part the growth of benzole as a motor-fuel was stimulated by the development of production facilities during WW1 (for explosives) which made it cheaper and more plentiful than imported petrol.

Crude benzole contains small quantities of a large number of impurities which consists of the unsaturated and sulphur compounds. One of the effects of these materials is to create a poor fuel. For the manufacture of explosives, such as TNT, particularly high grades of toluene are needed, and this requires a "catalytic" refing process. Crude benzol contains sulphur compounds (and other things) which will "poison" the catalyst and the refining of benzole therefore assumed a military as well as an economic importance.

To remove the impurities, the crude benzole is washed with concentrated sulphuric acid which sulphonates the more undesirable compounds and allows easier separation and recovery of the benzene, toluene and xylene (BTX) fractions. The sulphuric acid washing removes unsaturated compounds, olefins, dienes etc. together with any pyridine and some sulphur compounds. The sulphuric acid treatment produces a thick, dark brown residue which is known as "acid tar". In some processes a clay (such as bentonite) may be present in the mixture. The sludge deposited into the pit at Hoole consisted of a mixture of tar-like hydrocarbons. which included spent bentonite and absorbed heavy oil, sulphuric acid and other oily substances. The acid-tar process has nowadays been superceeded by "cleaner" methods.


Lobitos had a brief moment of fame in 1931.

Gunpowder contains the nitrate saltpetre as a source of oxygen to maintain combustion. In medieval times enough of this could be obtained from dung-hills and latrines, or from bat guano in caves. By the mid-19th century, however, far more powerful "high" explosives like nitroglycerine and TNT were being prepared by using a mixture of concentrated nitric and sulfuric acids to attach nitrate groups directly to suitable organic molecules, such as toluene. This produces an explosive which detonates rather than simply burning rapidly, as with gunpowder. Such explosives became particularly important was the successor to gunpowder in naval warfare after the development of ironclads which gunpowder-using weapons could hardly scratch.

TNT is well suited to use in naval warfare as it is a powerful explosive but quite stable to shock and friction. This is important as a more sensitive material might explode inside a shell when a gun is fired. Unlike gunpowder TNT is fairly difficult to explode and was used for years as a dyestuff before the potential as an explosive were recognised. TNT melts at 80 °C (176 °F), far below the temperature at which it will spontaneously detonate, allowing it to be poured or safely combined with other explosives. TNT neither absorbs nor dissolves in water, which allows it to be used effectively in wet environments. The German armed forces adopted it as a filling for artillery shells in 1902. TNT-filled armour-piercing shells would explode after they had penetrated the armour of British capital ships, whereas the British Lyddite-filled shells tended to explode upon striking armour, thus expending much of their energy outside the ship, despite picric acid being a more powerful explosive.

The critical raw materials for the production of explosives were now caliche – a nitrate-rich mineral from Chile – and organic substances from various sources, particularly benzole from coal tar. In 1914, existing stockpiles of explosives and their chemical precursors proved woefully insufficient, even for the expected short war. One of the reasons that WW1 developed into a trench stalemate was that neither side had sufficient ammunition to break-through the lines of the other side, and an infantry attack against the lines without artillery would be suicidal. There are some suggestions in the literature that benzole itself was used as a shell propellant in WW1, although this may be an error with benzole only being used as a raw material for the manufacture of explosives, and these would be used in explosive shells rather that being used as a propellant (such as cordite). WWI Benzole extraction plants were installed alongside the coke ovens at collieries, gasworks, steelworks and tar distilleries for the manufacture of TNT and other explosives. The coal-tar derivatives were also important for the manufacture of dyes which could no-longer be obtained from Germany. National Benzole was established in 1919, just after the end of WW1 to make use of this established capacity.

By the Second World War it had become clear that petrochemical and fuel supplies were of immense strategic military importance. This was especially true given that most of the European powers had little or no natural supplies of oil. When Adolf Hitler took control of the country in the 1930s, he was keen to develop a domestic synthetic fuel industry. When WWII started, synthfuels refined from coal were a significant contributor to Germany’s energy needs. Benzole had become a strategic material. Unfortunately, synthetic fuel plants were a relatively easy bombing target.


Lobitos (it's name means "the port") is a now something of a ghost-town located on a somewhat desolate stretch of the northern coast of Peru in the region of Piura. It is known as a small fishing town and is famed for its surfing among those willing to travel to out of the way places, but has a long history of oil extraction dating back to the late 19th century. Indigenous people in Peru used the heavy oil/tar to waterproof baked clay containers, for medicinal purposes, and in lighting during religious ceremonies. Later the colonising Spaniards used it for caulking their ships. The first significant enterprise there was led by Balfour Williamson & company. Balfour Williamson & Co was a shipping company based in Liverpool, and later an export confirming house and freight forwarding company. The company was founded in 1851 by two young men from Fife, Scotland, Alexander Balfour and Stephen Williamson. They were joined for a time by a third partner, David Duncan. The company traded with South America, and had offices in Valparaiso, Chile and San Francisco. They built up a significant trading network along the Pacific coast of South America and established the "Peruvian Petroleum Syndicate" with other partners in 1901.

Lobitos in Peru is an unlikely place to start a story about Hoole.

The first wells at Lobitos were drilled in 1903 but actually turned out to be uneconomic. New and deeper wells were again drilled in the northern zone of Lobitos in January 1904 and these turned out to be much more viable. As of March 13th of 1908 the Peruvian Petroleum Syndicate ceased trading under this name and Lobitos Oilfield Company was established in London with shares being sold on the stock market. Lobitos had become something of a strange colonial outpost, with substantial Victorian houses of which a few still remain. Then came world war one and the beginning of American political muscle flexing abroad in regards to national security interests that included petroleum. The American Government felt that the British interests in Lobitos were too close to home and therefore exerted lobbying pressure to enable the International Petroleum Company (the Canadian Subsidiary of Standard Oil of New Jersey, later to become Exxon) to buy a 50% share of Lobitos Oilfields. This was part of a battle for oil that involved Standard Oil, a company with the name "British Controlled Oil-fields" and several invasions of South American countries. By the 1920's Lobitos Oilfield was producing 20% of Peru's oil.

The town and surrounding land was thereafter a mini British/American colony that was legally leased from the Peruvian Government, in which much needed infrastructure (pier, desalinization plants, electricity, cattle ranch and slaughter house, hospital roads etc.) was established for production and the needs of immigrant workers settling in the new town. On a rather deserted stretch of cosatline at the northen end of the Sechura Desert it is one of the most arid places on earth. At one point the most luxurious ocean liners in the world such as the SS Cuzco and SS Reina del Pacifico stopped off in the bay on their route from Liverpool to Santiago de Chile - if only because there was no other stop-off anywhere nearby. The Prince of Wales and Prince George visited Lobitos in 1931 on their way to the World Expo in Buenos Aires, Argentina. Such was the importance of this town, the first cinema in the South American continent was established there.

In 1934/5 Lobitos Oilfields opened a refinery at Ellesmere Port connected by a pipeline to Stanlow Docks. This was one of the first petrochemical facilities in the major expansion at Ellesmere Port from simply a storage location. Bulk imports to the port had started in 1922 and by 1934 the storage capacity was 90 million gallons. Shell initially built a plant which blended and distributed imported oil products. Before long, the plant also began to manufacture bitumen and special solvents such as turpentine substitute. Shell then purchased a large area at the mouth of the Gowy and by the outbreak of WW2 a wide range of petrochemical products were being produced. Stanlow’s products included aviation spirit, which was vital for the wartime air force. The construction of a complete crude oil refinery at Stanlow began in 1949 - part of the post-war move to locate refineries close to growing customer markets. It was completed in 1952. One consequence of this developing industry was that it attracted the manufacture of anti-knock compunds such as Tetra Ethyl Lead (TEL) to the area.

The Lobitos refinery was initially designed to deal with the low sulphur and wax-free crudes available from Peru to make special products such as white oils and cable oils. Petrol was marketed by a subsiduary which owned stations in North Wales. Some insight into the culture at Lobitos in Elesmere port is available from tapes made of employees. The collection of the Univrsity of Aberdeen contains records of oral history including a tape of Arthur Moulton Tilling (born 1916) who worked in the lab there after 1936: he:

  • "Recalls getting rid of acid sludge, repeated treatment that was necessary, tipping skips of acid in open drain. Describes related processes, interceptor to trap oil waste, reprocessing. Recalls state of water leaving refinery, going into river. Compares with requirements today. Explains final draining of acid from lube oils, neutralisation, pressurisation, monitoring processes. Saw a lot that others didn't see in refinery. Details re own suggestion, later followed up, of catching, re-using acid that was going down drain, saving to company." (MS 3769 - 'Lives in the Oil Industry' Oral History Archive & associated records)
Lobitos in Elesmere Port (1934). Note that the area is still relatively undeveloped.

In WW2 the Lobitos company suffered casualties. At 11.00 on 11 January 1940 the EL OSO, in convoy HX-14B, struck a mine laid on 6 January 1940 by U-30 and sank six miles 280 degrees from the Bar Lightship, Liverpool. Three crew members were lost. The master and 32 crew members were picked up by HMS WALKER and landed at Liverpool. One injured crewman subsequently died in hospital. The first major casualty on the West Coast in WW2, she carried 9,238 tons of Peruvian crude oil, and 511 tons of casinghead gas. One of the products handled at the refinery in wartime was some of Britain's only natural oil from Eakring in the Newark and Sherwood district of Nottinghamshire. During the war, the Nottinghamshire oilfield produced over 2.25 million barrels (358,000 m3) or perhaps 3.5 million barrels (560,000 m3) of oil from 170 pumps ("nodding donkeys"). Just why the Nottinghamshire oil was taken to Stanlow is unclear: it may have been a question of capacity, or it could have been that the oil was of a kind which required special refining techniques available at Lobitos. A branch of the PLUTO pipeline extended through Beeston Brook down the Gowy to Stanlow but it is not known whether the Nottinghamshire oil eventually found its way to Europe via this route, although it could have gone to airfields such as RAF Sealand via the national military pipeline system (an example of which passes through Upton at Butter Hill).

Another photograph of the Lobitos site at Ellesmere Port.

Benzole production for motor fuel was debated in parliament after WW2 (22nd January 1948). 54 million gallons had been produced in 1943, and this had fallen to 44 million gallons in 1947. Benzole as an alternative motor fuel in admixture with petrol was eventually phased out. Benzene and toluine are both far more toxic than petrol and the price of petrol fell below that of benzole. Alternative anti-knock cdditives also became available, although one of these (TEL) was lead-based and that caused significant release of lead into the environment. Production of TEL at Ellesmere Port continued long after it was banned in most countries but as of 2020 is believed to have ceased.

The town of Lobitos also had mixed fortunes. In 1968, with a new government in place in Peru, the International Petroleum Company occupying Lobitos was forced to leave and their property was seized by the government. Military bases were built and the British mansions were used to house the Peruvian military. The military occupation, however, was short-lived and, because of a peace agreement signed with Ecuador, the military base was slated to be removed. As the military left the land, the historical landmarks became vulnerable and began to be looted, which destroyed most of the area’s buildings, including the historic cinema. All that exists today is an old, dilapidated church and a couple of Victorian mansions-turned-hostels, which are just barely holding on amd usually get their custom from surfers.


The Brickworks.

Any glance at a map of Upton, Newton and Hoole immediately suggests the presence of clay. There are many glacial features in the lamdscape and a notable number of marl pits. Reference to a geology text will confirm that there is a layer of glacial clay over the underlying sandstone. During the Georgian and Victorian eras, brick became a popular building material and the growth of Chester northwards following the establishment of Chester Station, especially into Hoole demanded a ready supply of bricks.

Rolt Brothers and later Hartleys owned the Hoole Bank brickworks, although the existence of paperwork in other names suggests that it changed hands frequently. This could be taken to suggest that it was not a particularly profitable busiiness.

The process of brick making changed little over the years and essentially comprised: excavating and transporting the clay to the works; mechanical working of the clay through a pug mill where larger stones were removed or crushed and where water was introduced if necessary to bring the clay into a consistency where it could be moulded; squeezing a continuous slab of clay through a die which had the cross-section of a brick onto an iron table where it was cut into individual bricks by tensioned wires held in a frame; removal of the ‘green’ bricks by hand, on barrows, to the drying sheds which were heated by waste heat conducted from the kilns, removal of the dried bricks on barrows to the kilns, and; firing the kilns to bake the bricks using slack coal fed down tubes from a floor on the top of the kiln. The brickworks at Hoole bank does not appear on the 1898 OS map, but appears as quite extensive on the 1908 revision, suggesting that it was founded around 1900. The bricks manufactured would not be of the high quality Ruabon type used as facing in much 1890's building in Hoole, but of a lower-cost single-fired variety. These would be used as an alternative to Ruabon brick for lower-cost housing and for rear and interior walls.

According to a local resident who searched the Phillipson & Golder Street Directories the brickworks closed between the 1932/3 directory and the 1934/5 directory, leaving a large pit from which clay had been extracted.

The fenced-off claypit in Hoole is now filled with a bubbling mixture of toxic tar and corrosive sulphuric acid with a thin surface layer of water. The pool is not completely dead, as some specialised bacteria are capable of living under even these extreme conditions - "life will find a way". At times the bacterial "mats" are pushed upwards by gasses as waxy domes which emerge from the surface like boils.


Acid tar production is a result of three chemical processes; benzoIe refining, white oil production and oil re-refining. The waste dumped at Hoole was from benzole refining as described above, with the disused claypit forming a convenient receptacle. Most books which mention acid tar lagoons will mention the Hoole site, although it remains remarkably poorly known in the area. Another site used for dumping acid tar waste from Ellesmere Port was at Llwyneinion near Wrexham. For many years local residents near Llwyneinion were reassured that there was no risk of fire, but, in August 1980 that lagoon site caught fire, resulting in the temporary evacuation of nearby Rhosllanerchrugog. The production of acid tar as a wastle product of benzole refining had been recognised as a problem throughout the industry and methods had been developed (at ICI's Beckton works in London) during the 1950's to treat the waste.

The Hoole site tops many lists of acid tar pits in the world.

Lobitos was taken over (1962) by Burmah-Castrol Company, now part of BP Anaco, but continued selling motor-fuel under their own brand. In 1964 the company's sales of petrol amounted to 12 million gallons. Nearly 80 per cent, of this total was supplied to the retail market, about 70 per cent of it in Northern Ireland where about half of the nearly 300 retailers marketing its petrol had entered into so-called "solus" arrangements (which controlled supply). In England, on the other hand, most of the petrol sold was to retailers without solus arrangements. Lobitos also owned a few petrol stations in the later 1950s and 1960s, branded Lobitos, which they set up because the solus schemes were killing the independent retailer market. A few of these still exist, such as the one on the coastal Mostin Road near Gwespyr - a relic which has no direct connection with the Acid Tar Pit of Hoole.

Until about 1967-72 (estimates vary) acid tar waste arrived at the dumping site warm in a semi-fluid state, and therefore was simply poured into the pit. At least 62,000 tonnes of liquid acid tar was poured directly into the pit together with spent bentonite containing absorbed oil. Some writers have failed to identify a source for the waste, but there are plenty of photographs in existence of "Lobitos Benzole" rail tankers on train-spotter sites from Ellesmere Port and Stanlow. In addition to the acid tar waste, several chemical drums were also fly-tipped into the sludge. However, nothing is known about the origins, contents or amounts contained within these drums. There is no evidence that they are linked to the supposed local disposal of "nuclear waste" from the Shell Thornton facility (see: John Dyer's website).

The unlined acid tar lagoon occupies 1.1 ha, ranges up to 9 m deep and is underlain by mixed glacial deposits over red sandstone bedrock of Permo-Triassic Chester Pebble Beds Formation. The heterogeneous tar waste has developed semi-solid tar layers, but most remains in a viscous and mobile condition. A surface layer of rainwater less than 0.9 m deep covers much of the waste.

The very similar site at Llwyneinion near Wrexham caught fire in 1980, although local residents had been assured that a fire was "impossible".

In 2000 the contents of the pit were 44 % sulphuric acid, 42 % oil residues, 8 % sulphated oil residues and 6 % water. It was fenced-off in 1999, but there are seepages outside of the fence. Various strategies for remediation have been considered, but none implemented. Curiously, and seemingly by co-incidence the Barnett family of Hoole Hall, were the owners of "Rattlechain Lagoon" in Tividale (West Midland) later used as a phosphorous waste dump and another seriously contaminated site. The acid tar pit in Hoole has no apparent owner, Cheshire West & Chester Council would not wish to take on the ownership of what can be considered a poisoned chalice. The Environment Agency are happy that as long as it is fenced off from the general public that is the best that might be expected. The pit is not entirely devoid of life as some highly specialised bacteria are able to live under these extremely acid and toxic conditions.

In 2000 a report noted:

  • "Various remediation strategies have been assessed. They fall into two main categories; those involving encapsulation and on-site treatment of the acid tar and those aimed at removal of the material to facilities elsewhere in the country. Investigations and deliberations continue in order to determine the optimum way forward."

Proposals include shipping the waste to Germany for conversion into something less potentially harmful. As of 2021 no action had been taken.


Benzole production in the UK as a cheap petrol substitute manufactured as a by-produce of coal-gas and coke-making, has now been largely discontinued. There is some evidence to suggest that the government in the inter- and post-war period supported the industry as a means of maintaining a strategic independence from foreign oil imports and because of its connection with explosives manufacture. Eventually it became clear that benzene, the major component of Benzole, was so toxic and carcinogenic that it was wholly unsuitable for mass use as a fuel. Other "anti-knock" technologies existed and the risks associated with leaded petrol were downplayed significantly at the time. Although it was possible, from the early 1950's, to avoid dumping acid tar waste, and even known to re-use it at a small profit, Lobitos at Ellesmere Port did not invest in this technology. They almost certainly knew of it, and continued to fill old clay pits with hot, toxic, corrosive and potentially imflammable sludge. Their legacy can still be found in Hoole. Remediation (remedy) of the problem has been discussed, but with no-one to pay for it, the bubbling pool of over 60,000 tons of toxic waste remains.

Visiting the site is not recommended. The ground near the lagoon can give a false sense of stability but may suddenly give way. The contents of the lagoon are extremely toxic and the acidity can give rise to severe corrosive effects (e.g. skin burns, even corrosion of unsuitable footwear). Disturbance of the contents may release toxic gas and possibly inflammable/explosive vapours.

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