EXPLOSIONS IN NOVA SCOTIA COAL MINES — GILPIN. 69 



conditions for ready ignition of gas and prompt distillation of 

 coal dust, and an equally prompt propagation of the induced 

 explosions. 



In this connection the follo^ying remarks on Explosions in 

 Dynamite Factories, from Eissler's work on modern explosives, 

 are of interest : — 



"EXPLOSIVES DLTE TO EXTERNAL CAUSES. 



" Mr. L. J. LeConte holds that dynamite catastrophies are in- 

 timately associated with electric phenomena. He has for the 

 past ten years noted the circumstances attending the accidental 

 explosions which so frequently occur on the Pacific Coast of 

 North America, and he has found that, with the exception of 

 such as occur during thunderstorms, the explosions take place 

 during the violent, desiccating, north wind storms peculiar to 

 the winter and spring months in California, l)ut occasionally 

 happening in midsummer. 



" These winds, it must l)e remend)ered, have a velocit}^ of 50 

 miles per hour, and a relative humidity of about 20 per cent., hut 

 frequently as low as 15 per cent., though seldom as low as 5 per 

 cent. During the prevalence of the winds a prodigious amount 

 of electricity^ is developed by the friction of clothing, especially 

 when walking against the wind. One can thus easily generate a 

 spark half an inch long. The phenomenon is also strongly 

 marked in horses at work, the electricity causing their manes 

 and tails to liristle to a remarkal:)le extent. Mr. LeConte finds 

 in the electricity the exciting cause of these explosions, and in 

 the dust that prevails in the work, the medium through which 

 explosion is propagated, a dust explosion always preceding the 

 explosion of the mass of powder. 



" The explosions occur on the third or fourth day of the storm. 



" To test the theory, he made four predictions in 1882 and 

 1883, and in each case an explosion of considerable magnitude 

 occurred. To guard against these accidents, he suggests the use 

 of steam jets, such as have been so successfully applied in cotton 

 and flour mills, and in coal mines. 



"As explosions during thunderstorms are caused l)y the return 



