172 Dr Fyfe on the Comparative Value of Oil and Coal Gas. 
remarks on Gas-light ; not with the expectation of advancing any 
thing new, but merely with the view of collecting into a con- 
densed form, what has already been said on this subject, par- 
ticularly on the important question, Whether oil-gas can com- 
pete with coal-gas, in point of economy. 
Although, at the first erection of gas-works, the public feel- 
ing was strongly against them, on account of their supposed 
danger and offensive nature, this prejudice has gradually worn 
off. Though the danger of having large collections of gas has 
been rated at an enormous extent by Sir William Congreve, only 
one instance of the explosion of a gas-holder has happened ; and 
this occurred in the first filling of one at Manchester, through 
ignorance, and the carelessness of the workmen. The atmosphe- 
ric air not having been extracted, was, of course, allowed to mix 
with the coal-gas, and one of the men wishing to ascertain if the 
gas-holder was tight, applied a candle to a part, from which gas, 
mixed with atmospheric air , was issuing, which caused it to ex- 
plode, and tear the gas-holder in pieces. 
A few accidents have occurred, from the escape of gas from 
the pipes, but these have, iiTgeneral, been produced by the care- 
lessness of the workmen, and were of a trifling nature ; for when 
the gas does escape, it is only when it gets into some confined 
place, as a vault, or a common sewer, that it can, on the approach 
of flame, do any mischief. It has been advanced by some, that 
accidents may happen from the gas escaping from the burners, 
by forgetting to turn the stopcocks. No accident of this kind 
is, we believe, on record ; nor is it at all likely to happen. Shops 
and apartments of a dwelling-house are not close enough to keep 
the gas confined ; but allowing that they are, the quantity emit- 
ted, is too trifling, compared to that of the air. Coal-gas is most 
explosive when mixed with about 5 of air. In a room, then, of 
twelve feet each way, one burner, consuming five cubic feet per 
hour, would be sufficient to light it, but, in this apartment, there 
are 1728 feet, so that, to get an explosive mixture, and allowing 
there is no loss of gas, the burner must be left open upwards of 
fifty hours, or at least two days and nights, which is not likely 
to happen. When more lights are used, the apartments are of 
course larger, so that the same time would still be required. In 
those cases, also, in which the burners are left open, the odour 
