SOME CHEMISTRY OF EVERYDAY LIFE 185 



gases appear at both electrodes. By collecting a sufficient 

 amount of them for testing, the gas at the cathode is found 

 always to be hydrogen, and the gas at the anode is always 

 oxygen. These gases are apparently from the decomposition 

 of some of the water (H 2 O) of the solution. The process of 

 breaking up chemical compounds by passing an electric 



FIG. 59. Silver plating. The passage of the electric current through the 

 solution of a silver compound results in the deposition of a thin coating of 

 silver over the exposed surfaces of articles serving as the cathode (-electrode). 



current through their solutions is called electrolysis (electrical 

 analysis) . 



Instead of the sulphuric acid in dilute solution as electro- 

 lyte there could be used a solution of some compound of 

 silver. With a current sufficiently strong, silver as a metal in 

 the pure state would then be deposited on the cathode, 

 forming a thin even layer or " plate" over any suitable 



