374 CHEMICAL DISCOVERY AND INVENTION 



anything previously known, as for example in paving the streets, 

 and the extra demand would for a time at least tend to raise the 

 price again. At any rate there seems no reason at the present 

 stage of the researches which are going forward for rubber 

 planters to entertain alarm. The change, if it came about, would 

 not take place in a moment, and there would be ample time for 

 the land now occupied with rubber trees to revert to its primitive 

 use in the provision of food. 



CHAPTER XXVI 



EXPLOSIVES 



"... it was great pity, so it was, 

 This villainous saltpetre should be digg'd 

 Out of the bowels of the harmless earth, 

 Which many a good tall fellow had destroy'd 

 So cowardly ; and, but for these vile guns 

 He would himself have been a soldier." 



WHEN Shakespeare put these words into the mouth of Hotspur 

 the only use for gunpowder was in the practice of war, and for 

 purposes of destruction such as was contemplated in the Gun- 

 powder Plot of 1605. But though at the time of writing this 

 book the greater part of Europe is devastated and millions of 

 men are exposed to destruction by the wholesale use of ex- 

 plosives in war, it must not be forgotten that these agents have 

 been among the most powerful auxiliaries in the arts of peace. 

 It is only necessary to consider how many roads, railways, 

 tunnels, and water works have been rendered possible by the 

 use of dynamite and other blasting materials to perceive that 

 explosives have a civilising mission of their own, and probably 

 next to steam have done more to facilitate inter-communication 

 between different countries than any other of the works of man's 

 invention. 



The chemist of the twentieth century is acquainted with a 

 large number of substances which when heated or struck or in 

 some cases even merely shaken explode, but the great majority 

 of them are useless for practical purposes, being too unstable to 

 be handled or carried about without great danger to the person. 

 By an explosion the chemist understands the sudden production 

 of a relatively large volume of a gas or gases from a solid, liquid, 



