NATUBE-STTJDY LESSONS. 159 



6. (a) Examine the specimens to discover fossils. 



Compare, if possible, with similar forms now 

 living. Are they shells, corals, trilobites, 

 etc. ? Describe the fossils found. Compare 

 them with any living animals of similar form 

 that you may have found. In what situations 

 have you seen such living forms ? 

 ((5) Infer whether limestone was formed under water 



7. If these rocks were formed beneath the sea, what 

 changes must have taken place in the level of the land ? 



8. Examine a piece of limestone with a lens. Describe 

 its appearance. Are there any crystals in it ? 



g. (a) Weigh a piece of limestone, then place it in a 



fire till it is red hot. 

 {b) As soon as it is cold, weigh it again and note 



the difference in weight 

 (£■) What change has taken place in the limestone ? 



The part of the limestone which remains after it is roasted is quicklime, 



10. (a) Wet the quicklime with a little water and 



describe what happens. Note the change 



of temperature. 

 {b) Take a little sulphuric acid and add its ovn 



bulk of water to it. Note what happens. 



Why? 

 {c) What causes the rise in temperature when 



water is added to the quicklime? 



1 1. Put a piece of red litmus-paper on moist limestone 

 and then on the moistened quicklime. What happens 



in each case? 



When quicklime is treated with water until it will absorb no more, it 

 becomes siacked-lime. 



12. {a) Where have you seen slacked-lime used? 

 (J?) What use was being made of it ? 



