ON THE EXPL08IBILITY OF COAL OILS. 105 



simply due to the greatly increased quantity of the explosive gas accu- 

 mulated in large rooms, as compeared with the diminutive chambers of 

 common lamps. The extent of the danger to both life and property 

 is thus correspondingly magnified. Even adjacent buildings have thus 

 been damaged and many lives destroyed by such explosions of coal 

 gas. 



There is, therefore, the same danger of explosions in the use oi coal 

 gas in houses as in the use of coal oil in lamps where ordinary care 

 and caution are not exercised. Were about five parts of atmospheric 

 air mixed in a city gas-works with one part of the coal gas, and thus 

 distributed for use, the jet of gas kindled at a burner would;; communi- 

 cate the flame to the interior of all the main pipes and gas-holders, 

 and a general siumltaneous explosion of all would ensue. The same 

 parallel has been applied to excluding atmospheric air from the chambers 

 of kerosene oil lamps by keeping them filled with oil. 



To compare practically the violence of the explosion of common 

 coal gas with that of the inflammable kerosene coal gas and of naphtha, 

 a small tin vessel of the capacity of a factory lamp was made for the 

 experiments ; the results of which showed that the coal gas was the 

 most readily explosible, the extent of the explosion, however, being 

 only a slight puff from the orifice of the tin vessel. 



The slightness of all the explosions in the experiments that have 

 been recapitulated, is ascribable to the small proportion of one-fifth 

 pure oxygen gas contained in the atmospheric air, the remaining four- 

 fifths being composed of incombustible nitrogen. Were pure oxygen 

 substituted for the diluted atmospheric air, the explosions would have 

 been dangerously violent. Indeed, were the atmosphere composed of 

 pure oxygen, the iron grate-bars of a furnace would burn more bril- 

 liantly than the most combustible fuel placed thereon, and explosions 

 and conflagrations would continually occur with irresistible violence. 

 It is owing to the presence of the pure oxygen gas evolved by heating 

 saltpetre, and commingled with the carburetted hydrogen gas evolved 

 from the ignited pine floors and partitions of warehouses, that the most 

 frightful explosions have occurred, which have often blown up great 

 warehouses and destroyed many lives. This fact appears to have been 

 lost sight of in the numerous discussions of the questions of "the 

 explosibility of saltpetre," which have been published, and in the ex- 

 periments that have been made to solve practically this unsettled 

 question. These experiments have shown that where fragments of char- 

 coal, not finely pulverised, such as are produced from burning wood, 

 and from cloth commonly used for bagging, are thrown upon heated 

 saltpetre, a prolonged vivid combustion has ensued, termed deflagration 

 in contradistinction to explosion, the contact of the two substances 

 being confined to the surfaces of the solid masses. To produce ex- 

 plosive action with saltpetre and charcoal when ignited, it has therefore 

 been found necessary to pulverise both substances very finely and then 



