64 EXPERIMENTAL GENERAL SCIENCE 



to prevent freezing. Not until the water in freezing has given 

 up its latent heat is there danger to other things in the cellar. 



Practical Exercises 



1. When a substance is boiling, does the addition of more heat 

 increase its temperature or merely cause it to boil faster? 



2. How does this knowledge enable one to save gas in cooking? 



3. How warm can ice be made? Why? 



4. How would you attempt to make mercury solid? 

 6. How could iron be made liquid? 



6. What do you infer as to the temperature of liquid air? 



7. What inference do you make as to the temperature of liquid iron? 



8. Would you expect the boiling point of liquid air to be above or 

 below zero Fahrenheit? 



9. In a substance which can exist in all three states, which has the 

 most heat in it, the solid, the liquid, or the gaseous form? 



10. Which contains the least heat? 



11. Dissolve about 100 grams of sodium thiosulphate (the "hypo" 

 of the photographer) in about 10 cubic centimeters of boiling water, 

 heating until all is dissolved. Place in a florence flask, cover and set 

 away until cool. .Then drop into the liquid a crystal of the hypo. 

 What effect has this on the state of the substance? 



12. Account for the heat that appears in the foregoing experiment. 



