56 SCIENCE OF COMMON THINGS. 



Spring water sparkles. Eain water, why soft. 



338 What makes water bubble and sparkle f 



The air or gas contained in it. 



339 Why does soapy water, especially, lullle 1 



Because soap makes water tenacious, and prevents 

 the bubbles from bursting as soon as they are formed. 



330 When soap-bubbks are blown from a pipe, why do they ascend f 



Because they are filled with the warm air of the 

 lungs, which is lighter than cold air. 



331 Why is water fresh from the well or fountain more sparkling and 

 refreshing than the same water after it has been for some lime exposed to 

 the air ? 



All spring and well waters contain atmospheric air, 

 oxygen, and carbonic acid gases, dissolved in them. 



The amount of these substances contained in water, depends upon its 

 temperature, cold water dissolving and retaining a larger quantity than 

 warm or tepid waters. When cold waters from springs or fountains are 

 exposed to the air, they become elevated in temperature, and the gases 

 contained in them escape, rendering the water flat and insipid. The 

 principal agent in imparting a sparkle and freshness to water is atmo- 

 spheric air, and not carbonic acid, as is often supposed and taught. The 

 quantity of carbonic acid present in ordinary spring waters is generally 

 inconsiderable. 



333 Why is it difficult to wash with hard water f 



Because the water contains saline matters, which 

 deprive the water of a part of its solvent power. 



333 Why is it difficult to wash with soap in salt water ? 



Because soap is insoluble in salt water. 



334: Why does water clean dirty linen f 



Because it dissolves the stains as it would dissolve salt. 



335 Why does soap greatly increase the cleansing power of water f 



Because many stains are of a greasy nature ; and the 

 alkali of the soap has the power of uniting with greasy 

 matters, and rendering them soluble in water. 



336 Why is rain water soft f 



Because it is not impregnated with earths and mine* 

 rals. 



337 Why is it more easy to wash with soft water than with hard? 



Because soft water ^^nites freely with soap and dis- 

 solves it ; in hard water the soap is either insoluble 01 



