336 Common Science 



You have already done an experiment showing that 

 electricity can start chemical change, for you changed 

 water into hydrogen and oxygen by passing a current 

 of electricity through the water. 



The plating of metals is made possible by the fact 

 that electricity helps chemical change. You can nickel 

 plate a piece of copper in the following manner : 



Experiment 103. Dissolve a few green crystals of " double 

 nickel salts " in water, until the water is a clear green. The 

 water should be about 2 or 3 inches deep in a glass or china 

 bowl that is not less than 5 inches across. 



Lay two bare copper wires across the bowl, about 3 inches 

 apart, as shown in Figure 177. Connect the positive wire 

 from a storage battery, or the wire from the carbon of a 

 battery of three or four cells, to an end of one bare wire. 

 Connect the negative wire from the storage or the negative 

 wire from the zinc of the other battery to an end of the 

 second bare wire. 



Now fasten a fine bare wire 5 or 6 inches long around a 

 small piece of copper, and another like it around a piece of 



FIG. 176. The copper and the nickel cube ready to hang in the cleansing solut 



