115 
Every one at all acquainted with this subject will 
have learnt from experience that this habit of isolation 
may be recognised between the ventilating air and the 
inflammable gas of the mine, when in close proximity to 
each other. Even the little irregularities which unavoidably 
exist in the roof of the air-courses themselves, will often be 
found to contain the gas in a highly inflammable condition, 
whilst the current of ventilation is sweeping along the floor 
and lower level of the passage. It is to be feared that a sad 
misapprehension too frequently attaches to the quantity of air 
which may be caused to circulate through a mine, and that in 
proportion to the quantity, will be the purifying effect to be 
looked for. The incident ^of isolation already referred to, 
will at once suggest the fallacy of such a conjecture ; and the 
frightful consequences which ally themselves to such an 
imaginary source of impunity. It is a peculiar characteristic 
which nature has stamped upon this gas, that it possesses 
neither colour nor smell. And its presence is therefore to 
be ascertained or judged of, by expedients, which only a 
practical skill can safely deal with. And herein would seem 
to consist the weight of gravest responsibility with every 
owner of a colliery where this gas is liable to be generated ; 
a responsibility which stops not with himself, or the pecuniary 
interests which centre in him, but extends to every individual 
workman employed, whose safety and existence, from the 
moment of his entering the mine, are beyond his own 
control, dependent on the wisdom, intelligence, and care 
which the management and direction of the working is made 
to exhibit. No doubt the points of danger are generally 
known in practice, and a proper caution may be made 
to surround the existence of localities where unavoidable 
accumulations of inflammable gas have taken place. But a 
sad reflection on the past reveals how insecure are all the 
avenues of safety, where they become associated with con- 
