EXPLOSIBILITY OF COAL OILS. 341 



began to spread over the surface of the calico, and it was readily ex- 

 tinguisliable by the breath when first kindled. Although a single 

 calico dress may of itself be deemed dangerously inflammable, yet it 

 requires more time to become ignited whilst wet with kerosene oil, 

 but the intensity of the flame becomes Anally much greater. 



When a similar experiment was repeated on cotton cloth moistened 

 with burning fluid, camphene, and spirits of wine, the blaze spread 

 instantaneously over the surface of the cloth with terrific violence, 

 affording ample reason for the belief of an increased hazard in using 

 them in lamps even for household illumination ; and yet how few are 

 the disastrous accidents which have occurred from this cause, in 

 comparison of the vast number of cases where lamps supplied with 

 these inflammable liquids have been harmlessly used with ordinary 

 care. 



An important incidental security, resulting from the use of kerosene 

 in lamps, is an exemption from the crusts of coal which are found to 

 collect on the wicks where whale oil is burnt, and which not only 

 obscure the radiance of light, but frequently sparkle off upon adja- 

 cent combustible bodies. It is necessary often to trim the wicks of 

 whale-oil lamps, which in manufactories is frequently done by work- 

 men, impatient at the waning glimmer. The burning crusts of the 

 wick, knocked ofl" without regard to surrounding combustible matter 

 in cotton mills, has often set them on fire and burned them. Tur- 

 pentine is also used for lighting the wicks of such lamps, Avhich in- 

 creases the danger in cotton mills. For these reasons it is believed 

 that the comparative hazard from fire by the use of whale oil in lamps 

 in cotton mills is greater than where coal oil is similarly used, of the 

 quality before stated. 



Although pure sperm oil may be free from the preceding objection, 

 yet, so great is the temptation of a profit of about one dollar per 

 gallon from mixing the cheaper whale oil with sperm oil, that it has 

 become nearly impracticable to obtain a sufficient supply of the latter, 

 even for oiling machinery. So great, indeed, has been found the 

 difiiculty of procuring pure sperm oil in England for this purpose, 

 that the heavier coal oil has been there successfully substituted in 

 place of it for this special purpose. 



Ample capital and skill have recently been applied to the new 

 branch of business of the distillation of coal oils, and no deficiency 

 of an abundant future supply will hereafter occur for purposes of 

 illumination, or, when properly prepared, for lubrication of ma- 

 chinery. It appears that an entire cargo of coal oil has recently been 

 exported to Italy. The supply of coal oil will not fail until the 

 supply of coal in the depths of the earth becomes exhausted. How 

 long this may continue has already become a curious subject of cal- 

 culation. 



The consumption of coal for purposes of navigation, and for motor 

 power in the useful arts, is manifestly destined to go on, increasing 

 with an increasing population to a vast extent, whilst no compensa- 

 ting supply is accumulating in new deposits or formations of fresh 

 beds of coal to replenish the decreasing stock. In anticipation of the 



