SCIENCE OF COMMON THINGS. 57 



Action of soap on water. The sea, why salt ? 



becomes decomposed. The solvent power of water 

 increases also with its purity or softness. 



333 When we wash with soap in water what chemical action takes 

 place ? 



The soap is resolved into a fatty substance and an 

 alkali ; the alkali dissolves most of the organic sub- 

 stances which constitute the dirt which we wish to 

 remove, and the greasy matter effects by its lubricity 

 an easy washing away of the dissolved matter from 

 other substances. 



330 Why do wood ashes render hard water soft ? 



Because they contain a powerful alkali potash, 

 which removes or neutralizes those impurities in the 

 water which rendered it hard and unfit for washing. 



340 Why does sugar or salt give a flavor to water f 



Because the sugar or salt (being separated into very 

 minute particles) floats about in the water, and mixes 

 with it intimately. 



341 Why does hot water dissolve sugar and salt more readily than 

 cold water t 



Because the heat of the water assists its solvent ac- 

 tion, and opens for the water a passage through the 

 particles of the substance. 



343 Why is the sea salt ? 



The sea has undoubtedly derived all its salt and 

 other soluble mineral substances by washings from 

 the land. The streams that have flowed into it for 

 ages have been constantly adding to its quantity, until 

 it has acquired its present condition. 



343 Why is not rain water salt, although most of it is evaporated 

 from the sea f 



Because salt will not evaporate, and therefore when 

 sea water is turned into vapor, its salt is left behind. 



344 Is there more or less of salt in every spring, river, or lake ? 



The saline condition of sea water is but an exagge- 

 ration of that of all ordinary lakes, rivers, and springs ; 

 they all contain more or less of salt, but their contents 



