152 THE ART OF PROJECTING. 



1. Suspend oblong pieces of various metals half an 

 inch in length, and note whether they set themselves 

 equatorially or axially between the poles. Iron, 

 nickel, platinum, bismuth, antimony, zinc, tin, lead, 

 silver, copper, alum, glass, sulphur, sugar, bread, paper, 

 charcoal, are good substances to experiment with. 



2. Suspend a cube of copper between the poles, 

 and twist the thread so that the copper will rotate 

 rapidly by torsion. It will quickly be brought to rest 

 when the current is made to pass. 



3. Fill small very thin tubes with liquids, and sus- 

 pend them in the same manner. Try solutions of iron, 

 cobalt, water, alcohol, turpentine, and salt. 



4. Place the magnet upon the upper condenser of 

 the vertical attachment, and upon its poles place a 

 watch-glass containing a little water or sulphuric acid ; 

 project the water in the watch-glass, and notice the 

 distribution of light upon the image of the water. 

 Now complete the circuit. The water will change its 

 form slightly and the light will be differently refracted, 

 thus making it quite visible. Salts of iron or nickel 

 will scatter the light like a concave lens. 



5. Hold the flame of a candle between the poles. 



6. Blow small soap bubbles with oxygen and with 

 illuminating gas, and hold them as close to the poles as 

 possible or drop them so they will rest upon both. 



7. Heat a coin and place it just beneath the poles, 

 and then drop a piece of iodine upon the coin. The 

 heat will volatilize the iodine, and the purple vapor will 

 be repulsed. 



ELECTRICITY. 



Most of the experiments in electricity which can be 

 showri by projection require the use of the galvanom- 

 eter, such for instance as give evidence of the existence 



