SOME WAYS OF PRODUCING ELECTRICITY 183 



rub it briskly all over with a piece of fur or wool. Call some 

 people into the room and if they pass close to the balloon, they 

 will be surprised at the result. 



3. MAKE AN ELECTROSCOPE 



Fasten a piece of silk thread to a celluloid ping-pong ball or to 

 small pieces of cork. Hang this eight inches below a support. 

 Use this to see if objects like sealing wax, fountain pens, and combs 

 when rubbed with fur, wool, or silk are electrified. 



4. A TASTE OF ELECTRICITY 



Get a strip of copper and a strip of zinc about ^ inch wide and 

 two or three inches long. Fasten a copper wire to one end of each. 

 Touch the tongue with the two free ends of the copper wires. 

 Hold the ends of the wires not more than ^ inch apart. Dip the 

 ends of the metal strips (must not touch each other) into a salt 

 solution. Take off the copper wire, and bring the ends of the two 

 strips to the tongue quite near each other. Can you detect a 

 difference in taste when the current flows and when it does not? 



5. ELECTRICITY FROM A LEMON 



Use the zinc and copper strips in Demonstration 4. Cut two 

 slits in a lemon -|- inch apart. Work the knife around in each to 

 cut the tissue. Push the two strips of copper and zinc into the 

 slits but do not let them touch each other either inside or outside 

 the lemon. Test by taste to see if an electric current is produced. 

 Test with a compass. 



SCIENCE CLUB ACTIVITIES 



1. ELECTROSTATIC RACE 



Make your preliminary tests at home. What can you find that 

 will give you the strongest electric charge wax, comb, fountain 

 pen, rod of ebonite, hard rubber, or glass? Which gives you the 

 best results wool, fur, or silk? When satisfied with your results, 

 enter your science club contest which will be held on a named 

 future date. Pieces of paper of graded sizes will be provided, and 

 the contest is to see whose equipment, which he brings from home, 

 can lift the largest piece of paper clear from the table. 



2. A MAGNETIC BOAT 



Build your boat upon any design you may devise. The fol- 

 lowing suggestions may be useful to you : For the magnet use a 



