68 FRAGMENTS OF SCIENCE 



employ the self -same wire to connect the two ends of 

 the battery, and subject it to the same test. The iron 

 filings now crowd round the wire and cling to it. I 

 interrupt the current, and the filings immediately fall; 

 the power of attraction continues only so long as the 

 wire connects the two ends of the battery. 



Here is a piece of similar wire, overspun with cotton, 

 to prevent the contact of its various parts, and formed 

 into a coil. I make the coil part of the wire which con- 

 nects the two ends of the voltaic battery. By the attrac- 

 tive force with which it has become suddenly endowed, 

 it now empties this tool-box of its iron nails. I twist a 

 covered copper wire round this common poker; connect- 

 ing the wire with the two ends of the voltaic battery, the 

 poker is instantly transformed into a strong magnet. Two 

 flat spirals are here suspended facing each other, about 

 six inches apart. Sending a current through both spi- 

 rals, they clash suddenly together; reversing what is 

 called the direction of the current in one of the spirals, 

 they fly asunder. All these effects are due to the power 

 which we name an electric current, and which we figure 

 as flowing through the wire when the voltaic circuit is 

 complete. 



By the same agent we tear asunder the locked atoms 

 of a chemical compound. Into this small cell, contain- 

 ing water, dip two thin wires. A magnified image of the 

 cell is thrown upon the screen before you, and you see 

 plainly the images of the wires. From a small battery I 

 send an electric current from wire to wire. Bubbles of 

 gas rise immediately from each of them, and these are 

 the two gases of which the water is composed. The 

 oxygen is always liberated on the one wire, the hydro- 



