Firedamp

Firedamp is a flammable gas found in coal mines. It is actually the name given to a number of flammable gases, including methane. It is particularly commonly found in areas where the coal is bituminous.

Firedamp is explosive at concentrations between 4% and 16%, with most violence at around 10%, and caused much loss of life in coal mines before the invention of the Davy lamp. Even after the safety lamps were brought into common use, firedamp explosions could still occur from sparks produced when coal contaminated with pyrites was struck with metal tools. The presence of coal dust in the air increased the risk of explosion with firedamp, and indeed could cause explosions itself.

The Tyneside coal mines in England had the deadly combination of bituminous coal contaminated with pyrites, and a great number of lives were lost in accidents due to firedamp explosions, including 102 dead at Wallsend in 1835. A continuous flame was produced at Whitehaven sometime before 1733, described as being "a yard wide and two yards long." The miners dealt with it by piping it to the outside.

Rather than the Davy lamp, Tyneside miners used a Geordie lamp, a similar safety lamp designed by George Stephenson.

Damps

Gases (other than air) in coal mines in England were collectively known as "damps". This comes from the German word Dampf (meaning "vapour"), and was probably introduced when German miners and mine engineers were brought to England in the 17th century to help in the development of deep mining.

Other damps included blackdamp (carbon dioxide and other gases), and the insidiously lethal afterdamp (carbon monoxide and other gases) produced following explosions of firedamp or coal dust.

Accident at Courrières in Pas-de-Calais

1906, the firedamp killed 1200 Workers in a coal mine at the town of Courrières in Pas-de-Calais, France. The explosion propagated itself in the galleries, thanks to the dust, which served as a fuel source. A number of workers were trapped in the coal mine for several weeks, eating their own excrement, drinking urine, and eating horses, in an effort to survive.

From http://en.wikipedia.org/