198 EXPERIMENTAL GENERAL SCIENCE 



10. Dip a piece of soft iron rod or wire into some iron filings. Is soft 

 iron magnetic? 



11. Hold one end of a bar magnet against an iron rod and dip the 

 opposite end of the rod in iron filings. How does the magnet affect the 

 rod? 



12. Remove the magnet. What effect has this on the magnetism in 

 the rod? 



13. If two bar magnets are to be kept in a box, how should they be 

 placed with respect to each other? 



14. An iron bar or pipe that has stood in an erect position for some time 

 comes to have magnetic properties. By means of a compass, test such 

 an object and discover which end is a north pole. 



15. Sprinkle some iron filings on a sheet of paper or glass and slowly 

 move a bar magnet beneath. Make the same experiment with the filings 

 on a sheet of iron. Which of these substances is the best screen for 

 magnetic action? 



16. Which is the best test for a magnetized body, that it is attracted 

 by a magnet or repelled? Why? 



17. The Carnagie, a ship for making magnetic observations, is con- 

 structed without iron. Of what advantage is this? 



18. Why would a compass be unreliable near a mountain of iron 

 ore? 



