ON THE CAUSE OF EXPLOSIONS IN LAMPS. 
379 
from Sudbury afforded iuflamraable vapour at 83 degrees. But, curiously 
enough, the temperature of the bulk of the oil in the lamp that exploded never 
reached this point; for besides the greater part of the two gallons of oil, a 
portion of which was in the lamp at the time of explosion, the brasswork and 
fragments of the lamp had been forwarded to me, and I was thus enabled, after 
fitting on another glass body to experiment on what might be considered as the 
original lamp and original oil, and found by actual observations with thermo¬ 
meters, introduced through holes bored in the sides of the lamp, that the oil in 
the interior rose no higher than 78 degrees, even after five hours’ burning in an 
unusually warm room. On applying a light, however, at this temperature, to 
an opening in the lamp, an explosion ensued. In short, it was found that even 
when the oil in the lower part of the body of the lamp was not warmer than 
65 degrees, a mixture of vapour and 'air had formed in the upper part of the 
body and exploded on a flame being introduced. Here, then, was a sample of 
oil, a portion of which had been the source of an explosion under ordinary do¬ 
mestic circumstances, wdiich emitted no inflammable vapour under 83 degrees, 
w^hen tried outside the lamp, and yet which inside the lamp gave, at 60 to 70 de¬ 
grees, such a mixture of vapour and air that, should it catch fire, would inevit¬ 
ably explode. The explanation of this state of things w^as obvious. The oil, 
though at 75, 65, or even colder, had, in its passage up the wick to pass 
through the heated brasswork, the temperature of the gateway of which, the 
temperature of that part presented to the interior of the lamp, must have been 
high enough to cause the evolution of vapour into the air in the upper part of 
the interior. This temperature wms taken by appropriate means and found to 
be 108 degrees ; in a smaller lamp it was 105, and in other experiments varied 
from 100 to 110 degrees during an evening. The cause of the explosion was 
thus perfectly clear. An oil giving inflammable vapour at 83 degrees, and not 
apparently heated beyond 60 to 70 degrees, had actually been exposed, in a 
most complete manner, to a temperature of 108 degrees, resulting in the forma¬ 
tion of an explosive mixture, which accidentally ignited on turning down the 
wdck. Every person who had used this oil in a paraffin lamp of the usual form 
had, so to speak, been burning his candle over a charge of gunpowder, and were 
it not that the chances of the explosive mixture becoming ignited were exceed- 
ingly small, as will be presently shown, many explosions, before that now re¬ 
corded, must have attended the use of the oil. So, then, an oil giving inflam¬ 
mable vapour below 110 degrees, and burnt in a lamp of ordinary construction, 
yields, sooner or later, a gaseous mixture which, should it catch fire, will burst 
the lamp and scatter the oil, to the possible injury of property and danger to 
life. Practically, I have only obtained lamp-explosions with oils which give off 
vapour below 100 degrees, when examined in the test-tube in the manner above 
described. Unfoftuuately, fcurteen out of every fifteen specimens of “ crystal 
oil,” “ pliotogen,” “American paraffin oil,’’ and other varieties of petroleum 
now sold for illuminating purposes, generate the explosive mixture at tempera¬ 
tures much below' 100 degrees, and hence are dangerous. The same remark does 
not apply to Young’s paraffin oil, but there is reason to fear that this mineral 
oil is often diluted with dangerous American oils. Other home-made mineral 
oils also vary in explosibility. 
The explanation of the occurrence of dangerous mineral oil in trade was 
fully traced out in my last paper ; three sentences, therefore, will be sufficient 
on this head. Crude petroleum having been found to be inflammable at com¬ 
mon temperatures, an Act was passed in 1862, forbidding, except by license, 
the storing of petroleum and its products near a dwelling-house or warehouse 
in larger quantities than forty gallons, unless proof was forthcoming 'that it 
gave off no “ inflammable vapour at a temperature of less than one hundred 
degrees of Fahrenheit’s thermometer.” Unfortunately this was taken to mean, 
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