170 



THE REASON WHY. 



"But the land, whither ye go to possess it, is a land of hills and valleys, and 

 drinketh water of the rain of heaven." DETJT. xi. 



756. What element is tlie most abundant in nature ? 



Oxygen, which forms so large a part of water. Of animal 

 substances, oxygen forms three-fourths ; of vegetable substances it 

 forms four-fifths ; of mineral substances it forms one-half; it 

 forms eight-ninths of the waters and one-fifth of the atmosphere ; 

 and aggregating the whole creation, from one- half to two-thirds 

 consists of oxygen. 



757. In what ways does man use oxygen ? 



Man eats, drinks, breathes, and burns it, in various proportions 

 and combinations. It is estimated that the human race consume in 

 those various ways l,000,000,0001bs. daily; that the lower animals 

 consume double that amount ; and that, in the varied works of 

 nature, no less than 8,000,000,0001bs. of oxygen are used daily. 



758. Why does water dissolve various substances ? 

 Because the atoms of water are very minute ; they therefore 1 



permeate the pores, or spaces, between the atoms of those bodies, 

 and overcoming their attraction Jor each other, cause them to 

 separate. 



759. Why does hot water dissolve substances more readily 

 than cold ? 



Because the heat assists to repel the particles of the substance 

 undergoing solution, and gives the water a freer passage between 

 the atoms. 



760. Why is pump water sometimes hard ? 



Because, in passing through the earth, it has become impregnated 

 with mineral matters, usually the sulphate and carbonate of lime. 



761. Why is rain water soft ? 



Because it is derived from vapours which, in ascending to the 

 clouds, could not bear up the mineral waters with them. It 

 therefore became purified or distilled. 



" 762. Why do kettles become encrusted with stony de- 

 posits ? 



Because that portion of the water which is driven off in steam 



