Solution and Chemical Action 



367 



FIG. 185. Making a glass of soda lemonade. 



while the caustic soda (NaOH) in the baking soda 

 neutralizes the acid of the sour milk. 



Effervescence generally due to the freeing of carbon 

 dioxid. Since baking soda is so much used in the home for 

 neutralizing acids, people sometimes get the idea that 

 whenever there is neutralization there is effervescence. 

 Of course this is not true. Whenever you neutralize 

 an acid with baking soda or washing soda, the carbon 

 dioxid in the soda bubbles up and you have effervescence. 

 But if you neutralize an acid with ammonia, lye, or 

 plain caustic soda, there is not a bit of effervescence. 

 Ammonia, lye, and plain caustic soda have no carbon 

 dioxid in them to bubble out. 



Baking powder is merely a mixture of baking soda and 



