LESSONS IN CHEMISTRY. 121 



a flash of flame, followed by a dense black smoke; the turpen- 

 tine is composed mainly of hydrogen and carbon, the chlorine 

 uniting with the hydrogen leaves the carbon free, which helps to 

 form the dense black smoke. 



Chlorine is a powerful bleaching agent. Pieces of calico or 

 other colored fabrics placed in chlorine gas, if dry, will remain 

 unchanged for some time, but when moistened the color will in 

 most cases disappear promptly. Some of the hydrogen is taken 

 from the coloring matter and oxygen set free, which doubtless 

 assists in decomposing the compounds which constitute the color, 

 but the action must not be allowed to continue long or the 

 fabric itself will be destroyed by the chlorine. 



For bleaching purposes chlorine is usually prepared from cal- 

 cium chloride, which readily gives off chlorine when acted on by 

 dilute sulphuric acid. An interesting experiment illustrating 

 the difference in specific gravity between chlorine and air may be 

 shown with the chloride of lime. On the bottom of a glass jar or 

 wide-mouthed bottle place a much smaller bottle containing some 

 bleaching-powder, add a little sulphuric acid, diluted by an equal 

 bulk of water and partly cover the larger bottle with a piece of 

 glass or pasteboard. Chlorine gas will be set free, will gradually 

 fill the smaller bottle, and failing over the sides to the bottom of 

 the larger one will gradually crowd out the air till it fills the bottle. 

 With a small bottle as a dipper the gas may be dipped out and 

 poured into other jars. Care should be taken not to breathe 

 the gas. 



Hydrogen is an important ingredient in many unpleasant, un- 

 healthful odors, and the strong affinity of chlorine for hydrogen 

 makes it a valuable disinfecting agent in such cases. It removes 

 the hydrogen, breaking up the compounds, and the oxygen set 

 free oxidizes or burns other parts into harmless compounds. 



Chlorine combines with hydrogen even more promptly than oxy- 

 gen does. If hydrogen and oxygen be mixed in the proper pro- 

 portion for water, they will not combine except by the aid of heat, 

 as the electric spark. While if hydrogen and chlorine be mixed 

 in the same way the combination takes place with explosive vio- 



