ON THE EXPLOSIBILITY OF COAL OILS. 103 



Finding by actual observation that only the gaseous vapours arising 

 from the heated oil exhibit the phenomenon of flame whilst ascending, 

 and combining chemically with the oxygen of the air, it became mani- 

 fest that no explosive action could be anticipated to take place from any 

 kind of oil or inflammable spirits, unless these gaseous vapours were 

 first evolved by a previous increase of temperature, and then brought 

 into contact with the atmospheric air before applying a match thereto. 

 There being no room left for either the gaseous vapour of the oil or for 

 atmospheric air to combine therewith, in the chamber of any lamp 

 entirely filled with oil, every attempt to produce explosive action with 

 a full lamp, at all temperatures up to the boiling point of water, utterly 

 failed when lighted matches were applied to the open orifice of the 

 lamp. The only result produced by increasing the heat of the coal oil 

 was an increase of the evaporation of the gas, and a higher jet of flame 

 steadily rising, as from the jet of a gas-burner. So long as lamps are 

 kept full of oil, or even of explosive camphine and " burning fluid," 

 there can be no explosive action whatever. For this special reason it 

 may be adopted as a safe rule to cause all lamps containing highly in- 

 flammable liquids to be kept as full as practicable by being daily re- 

 plenished. 



As nearly all the published accounts of the explosions of camphine 

 lamps, and of the consequent dangerous and frequently fatal conse- 

 quences that have ensued, represent the occurrences to take place during 

 the process of filling them whilst empty, the chamber of the lamp or of 

 the feeder being then occupied by gaseous vapour commingled with 

 atmospheric air, an experiment was made with a glass factory lamp under 

 similar circumstances, as being favourable for exhibiting the most 

 violent explosive action producible by means of coal oil. Accordingly 

 a lighted match was plunged into the orifice oi a burning lamp contain- 

 ing a little kerosene oil of the ordinary temperature, without producing 

 any perceptible explosive effect. In this state it was also filled safely. 

 To test the effect of increasing the heat of the coal oil higher than 

 80 deg., the lamp, whilst still burning, was placed in a basin of water, 

 the temperature of which was gradually raised to the boiling point. 

 During the progressive increase of temperature burning matches were 

 continually inserted into the orifice of the lamp without perceptible 

 effect in kindling vapour, until the heat became increased to nearly the 

 temperature at which the oil had been found susceptible of being 

 kindled in an open cup. The only mode of producing a slight ex- 

 plosive puff on inserting a burning match, was by violently skaking the 

 lamp to increase the evaporation and mix the gaseous vapour more 

 thoroughly with the atmospheric air. But when the temperature of 

 the coal oil became further increased to about 160 deg., the rising 

 gaseous vapour entirely filled the chamber of the lamp and expelled 

 the atmospheric air so completely as to cause lighted matches to be ex- 

 tinguished within the chamber, whilst the ascending gas continued to 



