42, 



DIGEST OF A LECTURE 



ON 



"EXPLOSIVES," 



BY 



W. POPPLEWELL BLOXAM, Esq., F.C.S. 



DEMONSTRATOR OF CHEMISTRY, ROYAL NAVAL COLLEGE, 



GREENWICH. 



i3//i JANUARY, 1886. 



It is my intention to demonstrate by experiments, within 

 the limit of an hour's lecture, a few of the leading pro- 

 perties of explosives which are in use for warlike or 

 industrial purposes to-day. As, perhaps the simplest 

 example of an explosion, I may shew the bursting of a paper 

 bag, inflated with air, by driving it sharply on to my hand. 

 In this case the air contained is suddenly compressed by the 

 force of the blow, and its elastic force becomes too great 

 for the paper envelope which is burst with almost explosive 

 violence. 



We have now to consider the technical meaning of the 

 terms Explosion and Explosive. 



An Explosion is said to occur when a solid or liquid 

 substance is suddenly changed into gas or vapour, the gas or 

 vapour occupying very many times the volume of the 

 original solid or liquid, and, in addition, greatly expanded by 

 the heat generated at the moment of explosion. 



Any substance capable of undergoing such change 

 upon the application of heat or other disturbing cause, is 

 called an Explosive. 



All explosives may be divided into two classes : (i) Ex- 

 plosive compounds (ii) Explosive mixtures. 



In an Explosive Compound all the elements present are 

 in chemical combination, though the force holding them 



