186 



ELEMENTARY GENERAL SCIENCE 



CHAP. 



this up and try and arrange matters so that the wire of Expt. 

 183 in connection with the copper and zinc plates is parallel to 

 the magnet when the latter is pointing north and south (Fig. 

 95). Notice that this is impossible. The wire exerts some 

 sort of power on the needle. 



FIG. 95. Experiment 184. 



EXPT. 185. Wind the wire which is connected with the 

 copper and zinc plates round a piece of soft iron, as in Fig. 

 96. Notice that the piece of soft iron will attract iron filings. 



FIG. 96. Experiment 185. 



EXPT. 186. Repeat Expt. 184, and notice that after a time 

 the power which the wire exerts over the magnetic needle 

 becomes feebler, and by and by ceases. Rub the copper plate 

 with a piece of wood until all the bubbles of gas which had 



