﻿112 Canadian Tlirord of Science. 



from t)iu rapidity with which each Hows out. The com- 

 mon gas Hows out more rapitlly and burns with a higher 

 flame than the acetylene, because it is lighter : (density 

 of Boston gas = 0.607 ; density of acetylene = 0.91). At 

 the last the flame strikes down into the small residue of 

 each gas, which has become mixed with air in the lamp 

 chimneys, and a slight explosion takes place, which is 

 notably stronger with acetylene than with gas. The 

 greater density of acetylene explains partly why it should 

 have more illuminating power than common gas, since a 

 cubic foot contains more material. As our object is only 

 to examine the properties of acetylene which have a bear- 

 ing upon its illuminating power, one test of its chemical 

 activity will suffice. Set free a small quantity of hypo- 

 chlorous acid gas in a tall glass jar and plunge into it a 

 tube from which a stream of acetylene is issuing, this 

 latter will immediately take fire from the great heat 

 evolved by its chemical action upon the hypochlorous 

 acid. If common gas, or almost any other gas, were sub- 

 jected to the same test, no flame would result. 



Acetylene forms peculiar salts with copper, silver and 

 mercury ; and these when dry decompose explosively 

 wlien subjected to a shock or to the action of lieat. The 

 silver compound can even be exploded under water and is 

 more dant^erous than fulminate of silver. 



EXPLOSIVEXESS OF ACETYLENE. 



What we have learned concerning the extreme chemical 

 activity of acetylene leads us to expect tliat it would form 

 more readily than other gases an explosive mixture with 

 air, and this proves to l)e the case. 



Experiments using a piece of two-inch gas pipe as a 

 cannon show that o-6% of acetylene mixed with air 

 forms an exi)losive mixture; 10-12^ of water gas is re- 

 quired to ex})lode with air. 



