SALT. FROST. 357 



Q. Why does SALT DISSOLVE ICE ? 



A. .Water freezes at 32, but salt 

 and water will not freeze till the air is 

 25 colder : if, therefore, salt be added 

 to frozen water it becomes liquid, unless 

 the thermometer stands below 7, (which 

 it never does in our island). 



Q. Will any thing do INSTEAD of SALT ? 



A. Yes ; any acid, such as sulphu- 

 ric, nitric, &c. 



Q. Why are SALT and SNOW mixed together, 

 colder than SNOW ? 



A. When salt is mixed with snow, 

 it dissolves the crystals into a fluid \ 

 and whenever a solid is converted to a 

 liquid, heat is absorbed, and the cold 

 made more intense. 



Q. Why does FROST make the EARTH CRACK ? 



A. During the warm weather the 

 earth absorbed abundance of moisture, 

 which the winter freezes : and (as water 

 expands by frost) the expanding water 

 thrusts the particles of earth apart from 

 each other, and leaves a chink or crack 

 behind. 



Q. Shoiv the WISDOM of GOD in this arrange- 

 ment. 



