Under this heading are generally classed all cases of quick or slow oxidation or combustion brought about by chemical, electrical, biological (bacterial) or physical processes (vibration, pressure, shock, or friction) only without the joint assistance of extraneous sources of heat (flame or hot glowing bodies). Spontaneous heating or spontaneous ignition has already been observed in practice to occur with the following substances, coal, lignite, briquettes, coke, lampblack, carbonized peat, metallic powders, slag heaps, etc. Fires produced by the influence of the sun's rays are generally regarded as a species of spontaneous ignition. These fires frequently occur in cases where least By the term explosive is generally meant gunpowder, nitro-glycerine, dynamite, blasting powders "and various other metals and substances, used or manufactured with a view to produce a practical effect by explosion or a pyrotechnic effect. Solid and liquid explosives represent gases or vapours condensed into the smallest possible compass in the solid or liquid form. Certain vapours may also be certified as explosive, The safety of explosive substances naturally increases with their purity, a factor which also influences their stability. Various inciting causes are needed to bring about the explosion as each substance is likely to behave differently. Some need to be struck, rubbed, heated, brought into contact with a flame or spark, compression, or subjected to percussion, ete. There are so many special peculiarities to be borne in mind in connection with explosive bodies that they require individual treatment in respect of storage, ete.
In passages and alleyways drop curtains constructed of asbestos would prove invaluable as a safeguard. They would retard and prevent the inflow of fresh air to the fire also, and this is so important, They would also have another advantage over the steel fire door by allowing an easy exit for persons trapped on the fire side of the curtain, as they would close automatically after their passage. Provided that the construction of adjacent walls, floors, and ceilings possesses- a high degree of fire resistance, the curtain would prevent the spread of fire for an indefinite period, but this would largely depend upon the degree of fire resistance in the connecting construction. Pure asbestos is quite fireproof and will not burn, one of its ied constituents being water.
Text read from the printed page and cleaned; old type leaves the occasional error.