ON THE EXPLOSIBII/ITY OF COAL OILS. 107 



Finding that the liquid naphtha evolved sufficient vapours at the 

 ordinary temperature of the atmosphere to become instantaneously- 

 kindled into flashing flames, the cup containing it was immersed in a 

 freezing mixture of snow and salt to reduce the temperature to the 

 zero of Fahrenheit's scale. At this low temperature, the naphtha 

 appeared to blaze with equal violence. Then a quantity of snow was 

 mixed with the liquid naphtha and thoroughly stirred, for still further 

 reducing the temperature. Even at this extreme degree of cold the 

 naphtha contin tied to flame so furiously that it was necessarily thrown 

 from the cup, upon the ice covering the ground where the experiment 

 was made, in the open air, whilst the thermometer indicated an atmo- 

 spheric temperature of 19 deg. below the freezing point. The naphtha 

 still continuing to burn upon the surface of the ice, a covering of snow 

 was thrown over it to extinguish the flame. Through this covering of 

 white snow the bright flames still continued to shoot up, presenting to 

 view the extraordinary spectacle of burning snow. 



On repeating similar experiments on the comparative combustibility 

 of spirits of wine or alcohol, camphine, and burning fluid, they did 

 not emit sufficient gaseous vapours at the freezing point, or 32 deg. to 

 become kindled into flame, when burning matches were plunged 

 therein, but with a little increase of temperature they all became 

 kindled. 



The preceding experiments seem to exhibit impressively the extra- 

 ordinary inflammability of naphtha, arising from the facility with 

 which it emits gaseous vapours. Susceptible of being readily kindled 

 into flames, even through a mantle of snow, naphtha, like ether, emits 

 gaseous vapour, which, with surprising facility pervades the air, and 

 the odour of it being rather pleasant than offensive, like that of arti- 

 ficial coal gas, the utmost caution is requisite to prevent not only 

 unexpected explosions, but also the almost unextinguishable violence 

 of its conflagration ; for, practically, the application of water does not 

 subdue the conflagration of naphtha in quantity, and only the exclu- 

 sion of atmospheric air appears to quench the fury of its flames. To 

 prevent the escape of the gas through the porous wooden staves, it 

 has been found necessary to coat the inside of the barrels with a solu- 

 tion of glue. 



. The insidious nature of the gaseous vapour of naphtha is therefore 

 its most dangerous quality, for when stored in barrels in a warehouse, 

 with the bungholes of the barrels open, sufficient vapour escapes into 

 the air of a close apartment to produce a violent explosive action on 

 introducing a lighted candle. In this way, notwithstanding the pre- 

 cautions used at the distilleries of coal oils, several of them have been 

 first shattered by explosions of the naphtha vapour and then burned 

 down. 



Petroleum contains a considerable per-centage of naphtha, and con- 

 sequently partakes in a degree of its dangerous properties There 



