PART III. LAND IMPROVEMENT 



CHAPTER X 



EXPLOSIVES 

 KINDS AND METHODS OF USING 



An explosive is a substance which can be suddenly changed 

 to a gas many times its original volume. A material that 

 burns under ordinary circumstances is combustible. The 

 finer the particles into which a combustible material is 

 divided and the more thoroughly mixed with air, the more 

 rapidly it will burn. Wood in a large stick is difficult to 

 set on fire. The same stick split into small kindling will 

 burn fairly easily. If cut into shavings, it ignites with a 

 spark. When ground into fine dust and suspended in the 

 air, it burns with explosive rapidity. An explosion of saw- 

 dust in a Philadelphia box factory caused the death of one 

 man and injured five others. The explosion was produced 

 by the contact of a cutter and a broken bolt, which generated 

 a spark, and this in turn ignited the sawdust particles in 

 the air. Serious explosions have occurred in corn-product 

 mills, candy factories, spice mills, linoleum factories, malted- 

 milk plants, and coal mines owing to the ignition of the 

 dust created during the processes of manufacture. It has 

 been estimated that a 25-pound sack of flour mixed with 

 4,000 cubic feet of air will, if ignited, generate enough 

 force to throw a ton of iron one mile. Marsh gas, coal gas, 

 acetylene, and gasoline vapor, when mixed with air, burn 

 so rapidly that the burning takes the form of an explosion. 



Oxygen in the air produces combustion; when the oxy- 

 gen is separated from the air and brought into contact with 

 burning bodies, the combustion is more rapid and com- 

 plete. Oxygen occurs in nature in many forms, one of 



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