Brass is an alloy of copper and zinc

: Methane explosions occur in mines when a build up of methane gas, a by product of coal, comes into contact with a heat source, and there is not enough air to dilute the gas to levels below its explosion point.

: Xenon is used in many different ways, from high-intensity lamps to jet propellant. But, the anesthetic properties of Xenon were discovered in 1939.  Xenon exerts its anesthetic properties through the non-competitive inhibition of N-methylD-aspartate receptors.