EXPECTATION 



2114 



EXPLOSIVES 



EXPECTATION, ex pek ta' shun, in the 

 common sense of the word, is a state of antici- 

 pating, or looking forward to some event. The 

 term is used by insurance companies to denote 

 the number of years persons may expect to live 

 under ordinary conditions. Tables of mor- 

 tality, as they are called, have been carefully 

 compiled from years of observation and ex- 

 perience, and are used as guides in fixing insur- 

 ance risks and costs. 



The following table of mortality takes as a 

 basis for calculation 100,000 persons at the age 

 of ten years. Of the 100,000 it is estimated 

 that 749 will die before reaching the age of ten. 



pressure. The essential constituents of an ex- 

 plosive mixture are a combustible substance 

 which in combustion yields gaseous products, 

 and an oxidizing agent. The force of the gases 

 generated during the explosion is utilized for 

 military and commercial purposes. The origin 

 of the most familiar form of explosive, com- 

 monly called gunpowder, is not definitely 

 known. Roger Bacon mentioned it about 1270, 

 and Berthold Schwartz of Freiberg, Germany, 

 described it about 1328. It was used by Ed- 

 ward I of England in his wars with Scotland. 

 Some authorities claim that gunpowder was 

 known to the Chinese centuries before it was 



Table of Mortality 



At the age of fifteen 96,285 are still alive, and 

 'their expectation of life, based on the ex- 

 perience of thousands of others, should be 45.50 

 years. Five years later 92,637 are living, with 

 probably 42.20 more years of life. At the age 

 of twenty-five the number alive would be 

 89,032, and their estimated allotment of life 

 38.81 years. At thirty, 85,441 of the original 

 100,000 are left alive. Carrying the calculations 

 out to the age of ninety, only 847 would be 

 alive, and the limit of their expectation would 

 be 1.42 years. The full table will be a matter 

 of' interesting study to every member of a 

 family. It appears above. 



EXPLORATION, ex plo ra' shun. See POLAR 

 EXPLORATION. 



EXPLQSIVES, eksplo'sivz, a variety of 

 substances which explode when ignited or when 

 struck or otherwise subjected to a sudden high 



discovered in Western countries, but of that 

 there is no absolute proof. 



Gunpowder. See the article GUNPOWDER. 



More Modern Explosives. The increase of 

 power in explosives effected by recent discov- 

 eries has necessitated improvements in guns 

 and cannon, and for many years there has been 

 a continuous race for effectiveness between 

 explosives, guns and defense works. The dis- 

 covery of guncotton by Schoenbein in 1845, and 

 of nitroglycerine by Sobrero in 1847, put the 

 science of explosives on an entirely new foot- 

 ing. In 1866 Nobel invented, or discovered, 

 dynamite, which at once revolutionized all 

 blasting operations. In 1886 Vieille produced 

 the first really successful smokeless powder for 

 military purposes. Nitroglycerine and gun- 

 cotton still hold the field as the most effective 

 for military purposes. All modem explosives 



