Solution and Chemical Action 355 



sourness; everything sour is an acid. Lemon juice, 

 sour milk, and sour fruits are all too weak acids to in- 

 jure clothes or skin, but their sour taste is a result of 

 the acid in them acting on the nerves of taste. 



Application 79. A girl wanted to make lemonade. She 

 did not know which of two knives to use, a steel-bladed one 

 or a silver-plated one. Which should she have used? 



Application 80. A woman was going to put up some 

 tomatoes. She needed something large to cook them in. 

 She had a shiny new tin dish pan, an older enamelware dish 

 pan, a galvanized iron water pail, and an old-fashioned 

 copper kettle. Which would have been best for her to use? 



Make a list of as many acids as you can think of. 



Inference Exercise 

 Explain the following : 



511. Sugar dissolves readily in hot coffee. 



512. The sugar disappears, yet the coffee flavor remains and so 



does the sweetness of the sugar. 



513. A tin spoon left overnight in apple sauce becomes black. 



514. If one's clothes are on fire, rolling over on the ground is better 



than running. 



515. Lemon juice bleaches straw hats. 



516. Will-o'-the-wisps glow at night, deceiving travelers by their 



resemblance to moving lanterns. 



517. Tomatoes should never be left in a tin can after it has been 



opened. 



518. Boiled milk tastes different from ordinary milk. 



519. Your hands become very cold after you have washed things 



in gasoline. 



520. Wood decays more quickly when wet than when dry. 



SECTION 55. Bases. 

 Why does strong soap make your face sting? 

 How is soap made? 



" Contains no free alkali," " Will not injure the most 

 delicate of fabrics," " 99^ % pure," such phrases as 



