58 
explosions by fire damp have been more frequent in the 
neighbourhood of Wigan than in the valley of the Irwell 
between Manchester and Bolton. All explosions of fire 
damp are caused by there being too much light carburetted 
hydrogen and too little air in the mine at the time. No 
one acquainted with the subject will question that the 
barometer and thermometer are of great use to the coal 
miner, but there may be, and apparently are, other causes 
which influence the ventilation of a mine besides the pres- 
sure of the atmosphere. The thick, heavy, and foggy 
weather often prevailing during the earlier and later 
months of the year appears to have something to do in 
fouling a coal mine, in addition to causing the air to be 
more sluggish in the workings. Now, in the ordinary state 
of the atmosphere, every one who has been in the dead parts 
of a coal mine — that is, in those parts where the air is not 
conveyed by artificial means — must have observed how 
slow the fire damp, and even the choke damp, are to diffuse 
themselves according to the law of {he diffusion of gases. 
You will find a stratum of fire damp at the top, one of air 
in the middle, and another of choke damp at the bottom. 
At present we are ignorant in what state water occurs in 
the atmosphere in thick, heavy, and foggy weather. It may 
be in a vesicular or some other condition between water 
and vapour which allows of the diffusion of gases in a mine 
far more speedily than in the ordinary state of the atmos- 
phere. To my knowledge, no experiments have yet been 
made to ascertain this fact, but it is very desirable that they 
should be tried, for both science and practice ought to do 
everything possible to prevent the terrible catastrophes 
which hurry into eternity so many of our most valuable 
workmen, and thus cause a national loss. 
Mr. Baxendell said it frequently happened when the 
atmosphere was in the state referred to by the Chairman 
that it had the power of rapidly bleaching test papers which 
