THE MODE OF TESTING MINERAL OILS USED FOR LAMPS. 645 
I am also of opinion that a gas flame should be employed in preference to a 
spirit-lamp, when the test is made in the manner directed by the Act, as a 
greater regularity in the rising of the temperature can be secured. I have em¬ 
ployed in my experiments, and I advise every one to do the same, the excellent 
suggestion made by Mr. Norman Tate, viz. a small flame of gas instead of that 
produced by a match or a taper, for ascertaining the flashing-point. I consider 
that the apparatus proposed by Mr. Mills would tend to give certainty to the 
trial, which at the present time cannot be satisfactorily performed. From the 
above experiments the following conclusion can be drawn, viz. that the Petro¬ 
leum Act of 1868 does not give sufficient and precise instruction for testing 
petroleum spirit; and that it is to be hoped that Government will take the 
matter in hand, and do away with the objections to the present Act, substi¬ 
tuting more clearly defined rules and instructions, so as to enable the operator 
to determine the flashing-point of petroleum spirit with a greater accuracy. 
THE MODE OF TESTING MINERAL OILS USED FOR LAMPS. 
BY BENJAMIN H. PAUL, PH.D. 
The degree of inflammability of the mineral oil now used for lamps is a character 
which the chemist is sometimes called upon to determine; and since recent inquiries 
appear to indicate that there is considerable difference of opinion as to the mode in which 
mineral oil should be tested for the purpose of determining that character, I have thought 
that this subject, though not one of any scientific interest, would be worth bringing under 
the notice of the readers of the ‘ Chemical News,’ especially since the degree of inflam¬ 
mability of mineral oil is now attracting considerable attention in reference to the ques¬ 
tion of danger attending the use of such oil in lamps. 
All kinds of mineral oil, whether derived from coal, or bituminous shale, or from 
petroleum, are, by their nature, more inflammable than the fat oils, such as sperm oil 
and colza oil, formerly used for lamps, that is to say, they take fire more readily and at 
a lower temperature than the latter; they also differ from those oils in being partially 
volatile at a temperature which has no similar effect upon the fat oils. Since the vapour 
thus given off is inflammable, and, when mixed with air in due proportion, capable of 
exploding, it is evident that the use of any kind of hydrocarbon oil requires, for both 
the reasons just mentioned, a greater degree of care than is necessary in the use of fat 
oils. 
In considering the question of danger to be apprehended from the use of mineral oil 
in lamps, the conditions under which it is used in a general way must be taken into ac¬ 
count ; and so far as the inflammability of the oil is concerned, the point to ascertain is 
not merely what oil may be used without any necessary danger, but what kind of oil will 
answer the purpose for which it is required as an illuminating material without, at the 
same time, requiring any greater degree of caution in its use than can fairly be expected 
under the circumstances. Even the more volatile portions of petroleum and paraffin oil, 
constituting what is generally termed “ spirit,” or naphtha, benzoline, ligroine, etc., may 
be burnt without any necessary danger in some of the ordinary paraffin lamps, which are 
constructed in such a manner that there is no free communication between the flame and 
the oil reservoir. But this material, which begins to boil below 100° F., and distils over 
completely below 300° F., while it is readily volatilized at the ordinary atmospheric tem¬ 
perature by contact with air, is much too volatile for general use in that way, except in 
the special form of lamp known as the “sponge lamp;” and, for that reason, it can 
scarcely be regarded as a suitable material for burning in what is termed the paraffin-oil 
lamp. The fact that it can be used in this way serves merely to show that any danger 
attending the use of mineral oil in lamps is less referable to its volatility and greater in¬ 
flammability, as compared with fat oils, than it is to carelessness or misuse, and the 
neglect of those precautions which the nature of this material renders indispensable. 
But, though the possibility of improper usage cannot reasonably be regarded as justifying 
any considerable restrictions in the application of a material so useful as mineral oil, still 
