CHEMICAL EFFECTS OF ELECTRICITY 91 



volume of oxygen. A solution which contains copper is sep- 

 arated into copper and the other constituents, thus making 

 copper plating possible. Nearly all' of the metals may be 

 used for electroplating, and they may be purified by this 

 method. The electric energy may be utilized to produce 

 certain forms of chemicals, and then the chemicals may be 

 used later to produce electricity. This fact is made use of in 

 the storage cell. The lead cell consists of two lead plates 

 which are immersed in dilute sulphuric acid. The plate at- 

 tached to the + terminal becomes coated with lead peroxide, 

 while the other plate becomes freed from all oxygen and is 

 practically pure lead. The lead plates now act as if they 

 were different elements and produce electricity similarly to 

 a rod of zinc and a rod of carbon in dilute acid. The Edison 

 cell uses nickel and iron for the plates. 



References : 



1. 1601 : 123. The Electrical Sources of Soil Nitrogen. 



2. 1703 : 38-39. The Electrolysis of Water. 



3. 1703 : 329-330. The Explanation of Electrolysis. 



4. 1803 : 292-298. Chemical Effects of Electricity, 

 a. 1701:366. Electroplating. 



6. 1801 : 349-354. Electrochemical Effects. 



c. 1804 : 474-478. Chemical Effects of the Electric Current. 



d. 1804:593-595. Electrotyping. 



e. 1807 : 407-411. Chemical Effects of Currents. 

 /. 1809:400-401. The Storage Cell. 



Experiment 30. Electroplating. 



Apparatus : Two dry cells with carbon of one connected with 

 zinc of the other, or one storage cell, beaker 250 c.c., strips of 

 copper, I"x5", connecting wires, German silver wire No. 22. 



Materials: Copper sulphate, paraffin, sandpaper, nitric 

 acid, 10 per cent, benzine. 



