On the Leniting Point of Petroleum. 339 
immersing the saucer in hot water, or otherwise, stiring the 
liquid with a thermometer, and applying a lighted match 
fromtime to time during the gradual rising of temperature 
until the oil caught light. The degree at which this oc- 
curred was said to be the igniting-point of the petreloum. 
But disputes as to the igniting-point soon occurred. Care- 
ful observers frequently noticed that several degrees before 
the petroleum finally ignited, a thinblue flame would seem 
to shoot from the lighted match to the surface of the liquid, 
or, as one experimentalist described it, “ the petroleum 
would appear to ignite and go out again,” and some would 
give this as the igniting point. Other observers not noticing 
this flame, or not operating under the circumstances causing 
it, found the igniting-point to be much higher. But ig- 
niting points were observed and stated which could not be 
accounted for by this cause of difference. Hence disputes, 
and hence arbitrations, which sometimes made the matter 
worse instead of better. Hence, too, which is the most 
serious part of the matter, much, if not most of the petro- 
leum sent up to the present time into retail commerce in 
the refinal state for use by the public gives off inflammable 
vapour many degrees below 100° F., and is unquestionably 
very dangerous. Slowly, and apparently carefully warmed 
in the manner alrcady stated, the petroleum does not fully 
ignite perhaps till 100° F. is reached, and the merchant or 
broker is satisfied, yet, as I shall presently show, inflamma- 
ble vapour is evolved at perhaps 80° or 85°, and should the 
inflammation of this vapour cause the fracture ofa lamp, or 
otherwise scatter the petroleum, danger to life and property 
ensues. 
The above is only a fair picture of the state of the petro- 
leum trade at the present time. My object in writing this 
paper isto show why the igniting-point of petroleum is 
liable to variation, and also to suggest a modification of the 
usual method by which that igniting-point shall be deter- 
mined with accuracy and constancy of results. And in 
speaking of igniting-point, I shall henceforward always 
mean temperature to which the petroleum must be raised 
before its vapour becomes inflammable. This is the point 
referred to in the Petroleum Act, and this is the point at 
which petroleum becomes dangerous. As already indicated 
the igniting-point of petroleum itself may be several and 
often many (sometimes thirty orforty) degrees higherthanthe 
igniting-point of the inflammable mixture of vapour and air 
on its surface, and the petroleum does not catch fire for the 
