334 EXPLOSIBTLITY OF COAL OILS. 



and begin to exhibit a lambent flame flickering over its surface, as 

 over that of bhizing alcghoL If the sample of oil contains much 

 naphtha, it will be found capable of emitting sufficient gaseous vapor 

 to take fire at the ordinary temperature of the air on plunging a burn- 

 ing match in a cup of the oil. Other samples will require to be 

 heated to 90°, and even to 160°, before they can be similarly kindled. 

 There is all this difference in the inflammability of the article sold in 

 the market for coal oil. Judging of all the qualities of coal oils by some 

 few cases of the explosive inflammability of the lowest grade in the 

 market, they have all been subjected alike to doubts and suspicions. 

 As the coal oils off'ered for sale by establishments of known respecta- 

 bility are really most valuable and economical substitutes for whale 

 oil for purposes of illumination, it is unwise, as well as unprofitable, 

 to embrace them all in one sweeping clause of condemnation without 

 experimental examinations to determine the facts in relation to this 

 novel subject of inquiry. 



The presence of naphtha in kerosene oil essentially contributes to 

 the brilliancy of the light for illumination, whilst at the same time 

 it improves the combustibility of the oil by a less tendency to emit 

 smoke. It is, therefore, for the interest of the consumer of coal oil 

 to retain as much of this light volatile spirits as can be safely used; 

 for it really seems like throwing away bread to reject so valuable an 

 element of human comfort and enjoyment available as a source of light 

 and warmth. The present waste of this material, which is now suf- 

 fered to take place from fear of its wonderful combustibility, will 

 probably be obviated ere long by new artificial chemical combina- 

 tions, as ether has been reduced to alcohol and wood sawdust to a 

 kind of sugar, so that its violent explosive tendency may be thus sub- 

 dued to a more safe and manageable condition for general use in lamps. 



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

 esting question for insurers as well as for the insured, having property 

 exposed to risks of fire from burning kerosene oil in lamps, to inves- 

 tigate carefully and judiciously the real extent of the danger and haz- 

 ards resulting from this use of it for illumination, so as not needlessly 

 to restrict the general enjoyment of this economical and valuable sub- 

 stitute for whale oil, and even coal gas. This investigation has be- 

 come the more important as th'e 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° to 

 212°. During the progress of the increase of temperature, blazing 

 matches were passed over the surface of the oil in each cup succes- 

 sively at sliort intervals of time, until the increased heat caused suf- 

 ficient gaseous vapors to arise from each to take fire; which they ail' 



