BASES I 4 I 



the most important characteristic of a base is that it will neutral- 

 ize an acid and in some measure lessen the damage done by it. 

 If you spill an acid on cloth, apply ammonia quickly and little 

 harm will be done. ' If you delay, the acid does its work and 

 there is no remedy. If soda (a base) touches black material, it 

 often discolors it and leaves an ugly brown spot ; but the appli- 

 cation of a little acid, such as vinegar or lemon juice, will often 

 restore the original color and counteract the bad effects of the 

 base. Limewater prescribed by physicians in cases of illness is 

 a well-known base ; it neutralizes the excess acids present in a 

 weak system and so quiets and tones the stomach. 



The interaction of acids and bases may be observed in another 

 way. If blue litmus paper is put into an acid solution, its color 

 changes to red ; if now the red litmus paper is dipped into a base 

 solution, caustic soda, for example, its color is changed back to 

 blue. What the acid does, the base undoes, either wholly or in 

 part. Bases always turn red litmus paper blue. 



Most bases are solids, like soda. But they are practically all 

 soluble in water, and when we speak of a base, we mean either 

 the solid base or its solution in water. Calcium hydroxide, for 

 example, is limewater, a solution of lime in water. Bases are 

 sometimes called hydroxides, owing to the fact that they all 

 contain hydrogen and oxygen. 



Bases, like acids, are good or bad according to their use. If 

 they come in contact with cloth, they eat or discolor it, unless 

 neutralized by an acid. But this property of bases, harmful in 

 one way, is put to advantage in the home, where grease is re- 

 moved from drain pipe and sink by the use of lye, a strong 

 base. Dilute ammonia is used in almost every home and is 

 an indispensable servant; diluted sufficiently, it is invaluable 

 in the washing of delicate fabrics and in the removing of stains. 

 In a more concentrated form it is helpful as a restorative in 

 cases of fainting. 



