144 INTRODUCTION TO GENERAL SCIENCE 



and to crops may be caused by the larger hailstones, which 



sometimes measure as much as two to three inches in 

 diameter. 

 References : 



1. 1103 : 159. Hail and Snow. 



2. 1304 : 249-250. Snow and Hail. 



3. 1803 : 99. The Formation of Clouds, Rain, Hail, and 



Snow. 



4. Weather Bureau. Photomicrographs of Snow Crystals. 



a. 1102 : 286-287. Snow and Hail. 



b. 1302 : 284-285. Snow and Hail. 



c. 1303 : 70. Snow and Hail. 



d. 1305:72-73. Snow and Hail. 



e. 1309 : 258-259. Hail and Snow. 

 /. 1807 : 200. Snow and Hail. 



Experiment 55. Sublimation. 



Apparatus : Burner, test tubes 6"X J", test-tube holder, 

 stirring rod of glass. 



Materials : Ammonium chloride, iodine, alcohol. 



a. Place a quarter teaspoonful of ammonium chloride in a 

 test tube and heat it. Does the ammonium chloride melt ? 

 Stick the rod into the test tube for a minute, then remove the 

 tube from the burner. Examine the rod. What has hap- 

 pened ? 



6. Repeat, using a few grains of iodine. What is the color 

 of iodine ? Of the vapor of iodine ? Describe the result. 



c. Dissolve the iodine with alcohol. State the difference 

 between melting a substance and dissolving it in some solvent. 



106. RAINFALL CYCLONES 



If the cooling of the warm air is carried beyond the forma- 

 tion of clouds, there will be so much water condensed that it 



