Fire-setting
Encyclopedia
Fire-setting is a method of mining
used since prehistoric times
up to the Middle Ages
. Fires were set against a rock face to heat the stone
, which was then doused with water. Written sources from antiquity
usually claim that this would cause the stone to fracture by thermal shock
, but experiments have instead indicated that the water (or any other liquid) did not have a noticeable effect on the rock, but rather helped the miners' progress by quickly cooling down the area after the fire. This technique was best performed in opencast mines
where the smoke and fumes could dissipate safely. The technique was very dangerous in underground workings without adequate ventilation. The method became redundant with the growth in use of explosives.
The oldest traces of this method in Europe were found in southern France
(département of Hérault
) and date back to Copper Age
. Numerous finds exist from Bronze Age
, such as in the Alps
, in the former mining district of Schwaz
-Brixlegg
in Tyrol
, or in the Goleen
area in Cork
, to name a few.
As for antique written sources, fire-setting is first described by Diodorus Siculus
in his Bibliotheca historica
written about 60 BC, about methods of mining used in ancient Egyptian gold mines. It is also mentioned in greater detail by Pliny the Elder
in his Naturalis Historia
published in the first century AD. In Book XXXIII, he describes mining methods for gold
, and the pursuit of the gold-bearing veins underground using tunnels and stopes
. He mentions the use of vinegar
to quench the hot rock, but water would have been just as effective as vinegar was expensive at the time for regular use in a mine. The reference to vinegar may come from a description by Livy
of Hannibal's crossing of the Alps
, when it was said that the soldiers used vinegar in fire-setting to remove large rocks in the path of his army.
Pliny also says that the method was used both in opencast and deep mining. That the method was used in practice is confirmed by remains found at the Roman gold mine of Dolaucothi in west Wales
, when modern miners broke into much older workings during the 1930s where they found wood ashes near worked rock faces. In another part of the mine, there are three adit
s at different heights which have been driven through barren rock to the gold-bearing veins for some considerable distance, and they would have not only provided drainage but also ventilation to remove the smoke and hot gases during a fire-setting operation. They were certainly much larger in section than was normal for access galleries, and the draught of air through them would have been considerable.
Fire-setting would have been used extensively during opencast mining, and is also described by Pliny in connection with the use of another mining technique known as hushing
. Aqueducts were built to supply copious amounts of water to the minehead, where they were used to fill tanks and cistern
s. The water was unleashed to scour the hillside below, both soil in the case of prospecting for metal veins, and then rock debris after a vein had been found. Fire-setting was used to break up the hard rocks of the vein itself and surrounding barren rock, and was much safer than use in underground workings since the smoke and fumes would be dissipated much more easily than in a confined space underground. Pliny also describes undermining methods were used to facilitate attack of the hard rocks, and probably the softer alluvial deposits too.
The method continued in use in the medieval period, and is described by Georg Agricola
in his treatise on mining and mineral extraction, De Re Metallica
. He warns about the problem of the "foetid vapours" and the need to evacuate the workings while the fires are lit, and presumably for some time afterwards until the gases and smoke had cleared. The problem raises the question of ventilation means in the mines, a problem often solved by ensuring that there was a continuous path for escape of the noxious fumes, perhaps aided by artificial ventilation. Agricola mentions the use of large water-powered bellows
to create a draught, and continuity of workings to the surface were essential for a stream of air to run through them.
In later times, a fire at the base of a shaft was used to create an updraught, but just like fire-setting, it was a hazardous and dangerous procedure, especially in collieries. As the number and complexity of the underground workings increased, care was needed to channel the air draught to all parts of the tunnels and faces. It was usually achieved by installing doors at key points. Most of the deaths in coal mine disasters were caused by inhalation of the toxic gases produced by firedamp
explosions.
The method continued in use for many years afterwards until finally made redundant by the use of explosives. However, they also produce toxic gases and care is needed to ensure good ventilation to remove those gases, like carbon monoxide
, as well as choice of the explosive itself to minimise their emission.
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
used since prehistoric times
Prehistory
Prehistory is the span of time before recorded history. Prehistory can refer to the period of human existence before the availability of those written records with which recorded history begins. More broadly, it refers to all the time preceding human existence and the invention of writing...
up to the Middle Ages
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...
. Fires were set against a rock face to heat the stone
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
, which was then doused with water. Written sources from antiquity
Ancient history
Ancient history is the study of the written past from the beginning of recorded human history to the Early Middle Ages. The span of recorded history is roughly 5,000 years, with Cuneiform script, the oldest discovered form of coherent writing, from the protoliterate period around the 30th century BC...
usually claim that this would cause the stone to fracture by thermal shock
Thermal shock
Thermal shock is the name given to cracking as a result of rapid temperature change. Glass and ceramic objects are particularly vulnerable to this form of failure, due to their low toughness, low thermal conductivity, and high thermal expansion coefficients...
, but experiments have instead indicated that the water (or any other liquid) did not have a noticeable effect on the rock, but rather helped the miners' progress by quickly cooling down the area after the fire. This technique was best performed in opencast mines
Surface mining
Surface mining , is a type of mining in which soil and rock overlying the mineral deposit are removed...
where the smoke and fumes could dissipate safely. The technique was very dangerous in underground workings without adequate ventilation. The method became redundant with the growth in use of explosives.
History
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
(département of Hérault
Hérault
Hérault is a department in the south of France named after the Hérault river.-History:Hérault is one of the original 83 departments created during the French Revolution on 4 March 1790...
) and date back to Copper Age
Copper Age
The Chalcolithic |stone]]") period or Copper Age, also known as the Eneolithic/Æneolithic , is a phase of the Bronze Age in which the addition of tin to copper to form bronze during smelting remained yet unknown by the metallurgists of the times...
. Numerous finds exist from Bronze Age
Bronze Age
The Bronze Age is a period characterized by the use of copper and its alloy bronze as the chief hard materials in the manufacture of some implements and weapons. Chronologically, it stands between the Stone Age and Iron Age...
, such as in the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
, in the former mining district of Schwaz
Schwaz
Schwaz is a city in Tyrol, Austria. It is the administrative center of the Schwaz district . Schwaz is located in the lower Inn valley, and has a population of about 13,000....
-Brixlegg
Brixlegg
Brixlegg is a market town in the Kufstein district in Tyrol, Austria. The town lies in the Lower Inn Valley and at the entrance of the Alpbachtal...
in Tyrol
Tyrol (state)
Tyrol is a state or Bundesland, located in the west of Austria. It comprises the Austrian part of the historical region of Tyrol.The state is split into two parts–called North Tyrol and East Tyrol–by a -wide strip of land where the state of Salzburg borders directly on the Italian province of...
, or in the Goleen
Goleen
Goleen is a small rural village in County Cork on the south-western tip of Ireland. Farming and construction work are the main occupations of the local people. Many are involved with some aspect of the tourist business, looking after some of the many holiday homes which surround the village...
area in Cork
County Cork
County Cork is a county in Ireland. It is located in the South-West Region and is also part of the province of Munster. It is named after the city of Cork . Cork County Council is the local authority for the county...
, to name a few.
As for antique written sources, fire-setting is first described by Diodorus Siculus
Diodorus Siculus
Diodorus Siculus was a Greek historian who flourished between 60 and 30 BC. According to Diodorus' own work, he was born at Agyrium in Sicily . With one exception, antiquity affords no further information about Diodorus' life and doings beyond what is to be found in his own work, Bibliotheca...
in his Bibliotheca historica
Bibliotheca historica
Bibliotheca historica , is a work of universal history by Diodorus Siculus. It consisted of forty books, which were divided into three sections. The first six books are geographical in theme, and describe the history and culture of Egypt , of Mesopotamia, India, Scythia, and Arabia , of North...
written about 60 BC, about methods of mining used in ancient Egyptian gold mines. It is also mentioned in greater detail by Pliny the Elder
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...
in his Naturalis Historia
Naturalis Historia
The Natural History is an encyclopedia published circa AD 77–79 by Pliny the Elder. It is one of the largest single works to have survived from the Roman Empire to the modern day and purports to cover the entire field of ancient knowledge, based on the best authorities available to Pliny...
published in the first century AD. In Book XXXIII, he describes mining methods for gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
, and the pursuit of the gold-bearing veins underground using tunnels and stopes
Stoping (mining method)
Stoping is the removal of the wanted ore from an underground mine leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to cave into the stope, although in most cases artificial support is also provided...
. He mentions the use of vinegar
Vinegar
Vinegar is a liquid substance consisting mainly of acetic acid and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. Commercial vinegar is produced either by fast or slow fermentation processes. Slow methods generally are used with traditional...
to quench the hot rock, but water would have been just as effective as vinegar was expensive at the time for regular use in a mine. The reference to vinegar may come from a description by Livy
Livy
Titus Livius — known as Livy in English — was a Roman historian who wrote a monumental history of Rome and the Roman people. Ab Urbe Condita Libri, "Chapters from the Foundation of the City," covering the period from the earliest legends of Rome well before the traditional foundation in 753 BC...
of Hannibal's crossing of the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
, when it was said that the soldiers used vinegar in fire-setting to remove large rocks in the path of his army.
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
, when modern miners broke into much older workings during the 1930s where they found wood ashes near worked rock faces. In another part of the mine, there are three adit
Adit
An adit is an entrance to an underground mine which is horizontal or nearly horizontal, by which the mine can be entered, drained of water, and ventilated.-Construction:...
s at different heights which have been driven through barren rock to the gold-bearing veins for some considerable distance, and they would have not only provided drainage but also ventilation to remove the smoke and hot gases during a fire-setting operation. They were certainly much larger in section than was normal for access galleries, and the draught of air through them would have been considerable.
Fire-setting would have been used extensively during opencast mining, and is also described by Pliny in connection with the use of another mining technique known as hushing
Hushing
Hushing is an ancient and historic mining method using a flood or torrent of water to reveal mineral veins. The method was applied in several ways, both in prospecting for ores, and for their exploitation. Mineral veins are often hidden below soil and sub-soil, which must be stripped away to...
. Aqueducts were built to supply copious amounts of water to the minehead, where they were used to fill tanks and cistern
Cistern
A cistern is a waterproof receptacle for holding liquids, usually water. Cisterns are often built to catch and store rainwater. Cisterns are distinguished from wells by their waterproof linings...
s. The water was unleashed to scour the hillside below, both soil in the case of prospecting for metal veins, and then rock debris after a vein had been found. Fire-setting was used to break up the hard rocks of the vein itself and surrounding barren rock, and was much safer than use in underground workings since the smoke and fumes would be dissipated much more easily than in a confined space underground. Pliny also describes undermining methods were used to facilitate attack of the hard rocks, and probably the softer alluvial deposits too.
Agricola
Georg Agricola
Georgius Agricola was a German scholar and scientist. Known as "the father of mineralogy", he was born at Glauchau in Saxony. His real name was Georg Pawer; Agricola is the Latinised version of his name, Pawer meaning "farmer"...
in his treatise on mining and mineral extraction, De Re Metallica
De re metallica
De re metallica is a book cataloguing the state of the art of mining, refining, and smelting metals, published in 1556. The author was Georg Bauer, whose pen name was the Latinized Georgius Agricola...
. He warns about the problem of the "foetid vapours" and the need to evacuate the workings while the fires are lit, and presumably for some time afterwards until the gases and smoke had cleared. The problem raises the question of ventilation means in the mines, a problem often solved by ensuring that there was a continuous path for escape of the noxious fumes, perhaps aided by artificial ventilation. Agricola mentions the use of large water-powered bellows
Bellows
A bellows is a device for delivering pressurized air in a controlled quantity to a controlled location.Basically, a bellows is a deformable container which has an outlet nozzle. When the volume of the bellows is decreased, the air escapes through the outlet...
to create a draught, and continuity of workings to the surface were essential for a stream of air to run through them.
In later times, a fire at the base of a shaft was used to create an updraught, but just like fire-setting, it was a hazardous and dangerous procedure, especially in collieries. As the number and complexity of the underground workings increased, care was needed to channel the air draught to all parts of the tunnels and faces. It was usually achieved by installing doors at key points. Most of the deaths in coal mine disasters were caused by inhalation of the toxic gases produced by firedamp
Firedamp
Firedamp is a flammable gas found in coal mines. It is the name given to a number of flammable gases, especially methane. It is particularly commonly found in areas where the coal is bituminous...
explosions.
The method continued in use for many years afterwards until finally made redundant by the use of explosives. However, they also produce toxic gases and care is needed to ensure good ventilation to remove those gases, like carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
, as well as choice of the explosive itself to minimise their emission.
Further reading
- Healy, JF, Pliny the Elder on Science and Technology, Clarendon Press (1999).
- Oliver Davies, Roman Mines in Europe, Clarendon Press (Oxford), (1935).
- Lewis, P. R. and G. D. B. Jones, The Dolaucothi gold mines, I: the surface evidence, The Antiquaries Journal, 49, no. 2 (1969): 244-72.