Mine Air

The Mine Air, or air in mines has been made the subject of considerable investigation. Freshly hewn coal evolves methane and other gases, and absorbs or occludes gases from the air, oxygen being taken up rather more rapidly than nitrogen. This is well exemplified by the following table which gives the relative proportions of oxygen, nitrogen,

	Freshly hewn Coal.	Coal exposed to Air.
Oxygen	8.8	23.8
Nitrogen	44.7	71.4
Carbon dioxide	1.6	1.18
Methane	44.6	3.5

carbon dioxide, and methane contained in samples of freshly hewn coal, and in other samples of the same coal after prolonged exposure to air.

It is not surprising, therefore, that the air of mines should exhibit a deficiency in oxygen and an increase in the percentage of carbon compounds. Analyses of air taken at different levels in a Scottish mine, are given by Whalley as follows:

	Oxygen.	Nitrogen.	Carbon Dioxide.
Near the floor	13.13	82.28	4.56
Near the roof	20.08	79.2	0.69
Near the coal face	18.97	79.8	1.21