102 ON THE ESPLOSIBILITY OF COAL OILS. 



take place from fear of its wonderful combustibility, will probably be 

 obviated ere long by new artificial chemical combinations, as ether has 

 been reduced to alcohol and wood sawdust to a kind of sugar, so that its 

 violent explosive tendency may be thus subdued to a more cafe and 

 manageable condition for general use in lamps. 



It has, therefore, now become an exceedingly important and interest- 

 ing question for insurers as well as for the insured, having property ex- 

 posed to risks of fire from burning kerosene oil in lamps, to investigate 

 carefully and judiciously the real extent of the danger and hazards re- 

 sulting from this use of it for illumination, so as not needlessly to re- 

 strict the general enjoyment of this economical and valuable substitute 

 for whale oil, and even coal gas. This investigation has become the 

 more important as the source of supply of coal oil appears to be limited 

 only by the supply of the vast beds of bituminous coal stored up in 

 reserve in the depths of the earth for future generations of mankind. 



To ascertain the comparative qualities of the kerosene oil made in 

 different parts of this country, samples were procured and tested by 

 the simple process of pouring some of each kind of oil into a cup by 

 itself, and by placing them all afloat together in a basin of water heated 

 by a spirit lamp, and with a thermometer immersed in the water to 

 indicate the temperature while gradually rising from 60 deg., to 212 deg. 

 During the progress of the increase of temperature, blazing matches 

 were passed over the surface of the oil in each cup successively at short 

 intervals of time, until the increased heat caused sufficient gaseous 

 vapours to arise from each to take fire ; which they all finally did, at 

 degrees of temperature varying from 80 deg. to 162 deg., exhibiting faint 

 flames quivering over the surface of the oil, precisely like those hover- 

 ing over the surface of spirits of wine or alcohol when similarly 

 kindled. The flames were quite as readily extinguished by a blast of 

 the breath, and not the least symptom of anj r explosive character be- 

 came manifest when each one took fire. Until the evaporative point 

 of each sample of oil was produced by the increase of heat applied, and 

 until lambent flames were kindled, burning matches were extinguished 

 when plunged into the coal oil, as effectually as if they had been simi- 

 larly plunged into water. The average heat at which all the samples 

 emitted sufficient vapour to admit of being kindled was about 125 deg. 

 of Fahrenheit's scale. 



After ascertaining the temperature requisite to kindle the several 

 samples of coal oil, it next becomes an interesting subject of investiga- 

 tion to ascertain the heat to which coal oil is ordinarily elevated whilst 

 burning in lamps. The results of actual experiments showed that in 

 glass lamps the temperature is increased about 6 deg., and in metallic 

 lamps but 10 deg. or 12 deg., above that of the apartment ; which, 

 being 67 deg., produced a heat in the oil of about 71 deg. to 79 deg., 

 leaving a considerable range of temperature below the average of 

 125 deg., above stated. 



