ON EXPLOSIONS OF FIEE-DAMP IN COAL MINES. 
15 
TABLE SHOWING THE LOSS OF LIFE IN BRITISH COLLIERIES FROM 1864 TO 1871. 
1864 j 
1865 1 
1866* 
1867 
1868 
1869 
1870 
1871 
870,881 
269 
1,075 
Estimated number of) 
men employed j 
Lives lost by explo- ) 
sions j 
Total lives lost 
307,542 
94 
867 
,315,451 
168 
984 
320,663 
651 
1,484 
333,116 
286 
1,190 
346,820 
154 
1,011 
345,446 
257 
1,116 
350,894 
185 
991 
These results are far from reassuring. The percentage of lives 
lost from accidents of all kinds seems to be slightly increasing 
every year, and last year amounted to very nearly three in every 
thousand : the proportion lost by the cause of accident we are 
now specially considering varies very much from year to year, 
but last year it was almost exactly one quarter of the whole. 
Fire-damp, the source of such a large part of the accidents 
incidental to coal-mining, is a mixture of carburetted hydrogen, 
nitrogen, and carbonic acid gases. Of these carburetted 
hydrogen is by far the largest ingredient, and, as the cause of 
explosions, the one we are more specially concerned with ; 
it is a compound of carbon and hydrogen (CH4), and in a 
pure state burns with a faint bluish-yellow flame : it becomes 
explosive when mixed with air, the violence of the detonation 
depending on the proportions of the mixture : if the amount of 
gas be not more than of the whole, the mixture burns 
without explosion, though the presence of tlie gas is distinctly 
indicated by changes, well known to miners, produced in the 
flame of a candle or lamp held in it. The maximum of ex- 
plosiveness is reached when the proportion of gas is from o^xth 
to ith : if a light be brought into such a mixture, the whole 
flashes into flame with fearful violence, and the unlucky miner 
whom it comes across is either scorched to a cinder or blown 
to pieces, or perhaps suffers both fates : when the gas is pre- 
sent to the extent of Jth, or a larger proportion, the mixture 
again burns without explosion : so large a proportion of gas, 
however, makes an atmosphere in which breathing is carried 
on with difficulty, and when the proportion of gas reaches Jrd, 
respiration becomes impossible. 
The products of the explosion are steam and carbonic acid, 
the latter a heavy gas, the presence of small quantity of which 
in air is immediately fatal to life. This floods slowly the pas- 
sages of the mine, and effectually stifles out any life that may 
have escaped the flame and concussion of the explosion. 
* This was the year of the Oaks explosion, in which 361 men were killed ; 
in the same year explosions occurred at Talk-on-the;>-Hill add Diikinfield, 
causing respectively 91 and 38 deaths. 
