WHAT IS WATER? 87 



SELF-TESTING EXERCISE 



Select from the following list those words which best fill the blank spaces 

 in the sentences below and arrange the words in proper numerical order. 

 A word may be used more than once. 



nitrogen evaporation impure mixture 



composition boiling cheap electrons 



compound union hydrogen oxygen 



elements twice oxygen separated 



rain costly water method 



pure molecules gas solution 



purifying distillation distilled stream 



Water is a (1) formed by the (2) of the elements 



(3) and (4) When water is separated into its (5) , 



it is found that there is (6) as much hydrogen as (7) 



When solids are dissolved in water, the water can be (8) from 



them if heat is applied. Heat causes some of the (9) of pure 



water to change to a (10) which leaves the (11) This 



process of (12) a liquid is called (13) The purest water 



that we make artificially is (14) water. When hydrogen 



burns (15) results which is also (16) , but this (17) , 



of producing (18) would be very (19) When distilled 



water is not available, the next purest water we can get is (20) 



water. 



STORY TEST 



CATHERINE REPORTS ON "WHAT Is WATER?" 



Read carefully and critically. List all the errors and suggest cor- 

 rections. 



It seems almost too commonplace to tell you what water is. 

 How can one ever be in doubt ? A glass of milk is white, ginger ale 

 is amber and has bubbles in it, sulphuric acid is very heavy, and 

 gasoline has an odor. If I can see, lift, and smell a liquid in a glass, 

 I can tell if it is water. Some may say a glass of lye (caustic soda 

 in water) or potassium cyanide solution would look the same as 

 water and could not easily be told by weight or odor. Even if this 

 is true, you could tell the difference after you drank them, so what 

 does it matter? The chemist tells us that water is made of hydro- 

 gen and nitrogen and that the amount of hydrogen is double that 

 of the other compound. When water is boiled, it goes off in two 

 separate gases, one of which will burn. Natural water is always 

 pure water, but the artificial water made by vaporization and 

 condensation is almost always impure. We have read a lot about 

 heavy water recently. That is water that has lead in it. 



