On the Cause of Explosions in Lamps. 3,21 
The remedy is plain. Let those who sell and those who 
buy discountenance the sale and use of those qualities of 
mineral oil which generate inflammable vapour at tempera- 
tures below 100 (better 110) degrees, when examined in a 
test-tube ina manner already indicated. Such tubes may 
be purchased for a few pence of any chemical apparatus 
maker, naked thermometers can be obtained at the same 
places, or these articles, together with an instrument for 
ascertaining the power of the oil to ascend a wick, a spirit 
lamp test-flame, jet, directions for use, &c., all enclosed in 
a neat pocket case under the name of the Petroleometer, 
are now kept in stock by Mr. Cassella, Hatton garden, 
London. Oils which stand the test may be considered safe, 
and such oils can be supplied by refiners as easily as 
unsafe ones,—it is only a matter of carrying the refining 
operation a little further. Indeed, safe oils are even now 
occasionally met with. At a shop in Drury lane I pur- 
chased petroleum at 4d. and at 44d. per pint; the former 
yielded inflammable vapour at 86 degrees, and gave me an 
explosion the first hour it was burnt in a lamp; the latter 
only emitted vapour at 114 degrees, and gave no explosive 
mixtureinalamp, even aftersevenhours’ burning. The use of 
safe oils will be the chief means of avoiding explosions. But 
the lamps themselves are not altogether faultless. The 
air-hole which allows the air entering the lamp and taking 
the place of escaping oil is usually within about half an inch 
of the flame, it might very well be placed at some other part 
of the lamp; for it is this aperture which forms the 
touch hole by which fire is conveyed from the flame to the 
explosive mixture within. Fortunately there is always a 
strong draught of air in the opposite direction, so that the 
chances are perhaps five hundred against, to one in favour 
of the accident, even though an explosive mixture be con- 
stantly in the reservoir. Were this not so, explosions with 
the petroleum now in commerce would be the rule rather 
than exception. Blowing down the chimney of a lamp 
neutralizes this current, and doubtless increasesthe chances 
of the flame reaching what I have already termed the touch- 
hole. Then this channel of communication might be packed 
with wires after the principle of the oxy-hydrogen safety jet. 
Again, the portion of the brasswork facing the interior of 
the lamp should be covered with bone, glass, or some other 
material, having bad conducting powers for heat, so that 
the gateway, as I have before called it, through which all 
the oil has to pass in ascending from the reservoir to the 
