30 



LABOBATOEY MANUAL 



Heat the water gently by playing the flame of the 

 Bunsen burner along the side of the test tube. What 

 change do you observe in the water level? 



Fig, 11. 



Again mark the level of the water. Cool the water 

 in the test tube by running tap water over it, or by 

 surrounding the test tube with ice. After a few 

 minutes note the level of the water. 



B. Fill the test tube with water. Tightly cork the 

 filled tube and after thoroughly drying the exterior of 

 the tube, gently heat it over the Bunsen flame. Explain 



