144 SMITH'S INTERMEDIATE CHEMISTRY 



or heated copper foil, burns in the gas, giving a fog of solid cupric 

 chloride 



Skeleton: Sb -f C1 2 -> SbCl 3 . 



Balanced: 2Sb + 3C1 2 -> 2SbCl 3 . 



Sodium burns brilliantly in chlorine, giving sodium chloride. 

 That a shining metal and a poisonous irritant like chlorine, in 

 uniting, should yield a mild, household article like common 

 salt illustrates very well the extraordinary nature of chemical 

 change. 



When thoroughly freed from moisture, chlorine no longer 

 combines with metals like copper and iron. Water seems to 

 be needed as a contact agent, in these, as well as in hundreds of 

 other chemical actions. Hence, carefully dried chlorine in com- 

 pressed liquid form can be, and is, stored and sold in iron cylinders 

 (see detinning, p. 508). 



Unites with Hydrogen. A jet of burning hydrogen, lowered 

 into a bottle of chlorine, continues to burn, giving hydrogen 

 chloride HC1, the presence of which is shown by the fog produced 

 by allowing the gas to come in contact with moist air: 



H 2 + C1 2 -> 2HC1. 



Hydrogen and chlorine, mixed, do not combine when cold, 

 provided strong light is excluded. But sunlight, or light from 

 burning magnesium (" flashlight powder "), starts the combina- 

 tion, which occurs with explosive violence. Plunging a lighted 

 taper into the mixture has, of course, the same effect. 



Acts upon Compounds Containing Hydrogen. Because 

 of its activity toward hydrogen, chlorine removes hydrogen from 

 many compounds. Thus, if a lighted wax taper be plunged into 

 chlorine, it continues to burn, though with a feebler flame. Dense 

 smoke, composed of particles of free carbon, rise from the flame. 



