Page:Popular Science Monthly Volume 24.djvu/477

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EROSENE, in virtue of its cheapness and the brilliant light it gives, has found its way into almost every house. And yet frequent and often horrible accidents prove that much of the oil now sold is of a most dangerous character. It is the recognized duty of the State to render the sale of such oil impossible by proper inspection. Almost daily reports of loss of property and life, as the result of the use of unsafe kerosene, show, however, that this official control fails to effect its object. This may be due, in a measure, to the undoubted negligence of cities and towns to appoint competent inspectors—if, indeed, any appointment is made—or to the carelessness of the inspectors; but of greater importance even than this are the low standards adopted, and the unreliability of the tests which are used to determine the character of the oil.

It is the object of this paper to consider the conditions of safety in an oil used for illuminating and heating purposes, and to give a brief sketch of the principal methods which have been proposed for determining this important point.

Petroleum, from which kerosene is prepared, is, as is generally known, a mixture of a large number of intimately related compounds of widely differing volatility. Some are gaseous, and escape in this form as the petroleum issues from the ground, while others form the solid paraffine. The middle portions of the crude oil are separated from the more and less volatile compounds by distillation, and after a further process of purification go into the market as kerosene. The entire removal of the lighter and more volatile portions, which are known as naphtha and benzine, is of the utmost importance, for it is in their presence that the danger lies. Alone, they are easily ignited, and alone or mixed even in small proportion with kerosene, they readily emit vapors which are inflammable and which with air form an explosive mixture.

An oil is safe only when it will not yield these dangerous vapors at any temperature which it is liable to assume. This temperature depends obviously (1) upon that of the place where the oil is kept or used, and (2) upon the influence of the heat of the burning wick in warming the oil in the reservoir of the lamp. As the result of carefully conducted experiments with lamps of different patterns, it has been found that the maximum increase of temperature of the oil