ELECTRODE 



2000 



ELECTROLYSIS 



desire. In the article CAPITAL PUNISHMENT are 

 listed the names of other states which followed 

 New York's lead. 



ELEC'TRODE, either terminal leading 

 from an electric battery or other source of 

 electromotive force. The word means the 

 electric way. It is by way of an electrode that 

 a current enters or leaves an electroplating 

 bath, a Crookes tube, etc. See CROOKES TUBES. 



ELECTROLYSIS, e lek trol'isis, the process 

 of decomposing a chemical compound by the 

 action of an electric current, that is, separat- 

 ing the compound into the original elements 

 or parts of which it is constituted. 



A simple experiment illustrating electrolysis 

 can be performed as follows: Connect four 

 dry cells in series; place the ends of the wires 



ANALYSIS OF WATER BY ELECTRIC 

 CURRENT 



leading from the dry cell battery in a solution 

 of common salt in water. Bubbles will rise 

 rapidly from the wire leading from the zinc 

 of the battery, the cathode, or negative pole. 

 In a short time a yellow color will appear 

 in the solution at the anode, or positive pole. 

 The salt has been separated into two parts, 

 sodium and chlorine; sodium ions bearing a 

 positive charge go to the cathode. There the 

 sodium reacts with the water, setting hydrogen 

 free. Chlorine ions bearing a negative charge 

 go to the anode. An ion is one of the sub- 

 stances which appear at the poles when elec- 

 trolysis occurs; that at the positive pole (the 

 anode) is called anion, and that at the nega- 

 tive pole (the cathode) is called cation. 



A substance which is decomposed in this 

 way by an electric current is called an elec- 

 trolyte. All acids, bases and salts are elec- 

 trolytes. In some applications of electrolysis 

 the electrolyte is kept in a molten state, as 

 in the separation of aluminum from its ores 

 (see ALUMINUM, subhead Its Manufacture). 

 Some of the useful applications of electrolysis 

 are the separation of some of the metals from 

 their ores, or electric smelting; the manufac- 

 ture of certain chemicals, such as bleaching 

 powder and potassium chlorate; electroplating, 

 and in refining copper (see COPPER, subhead 

 Preparation) . 



An injurious effect of electrolysis is the de- 

 composing of gas and water mains which run 



WATER PIPE DESTROYED BY 

 ELECTROLYSIS 



parallel to the track of a trolley line in which 

 the track is used as the return circuit. At 

 certain places where the ground is a good con- 

 ductor the current leaves the track and flows 

 along the gas or water pipes for some distance. 

 Where the current leaves the pipes electrolysis 

 of certain compounds in the soil takes place, 

 setting free chlorine or some other element to 

 attack the pipes and injuring them by eating 

 away the metal. The remedy lies in provid- 

 ing proper lines for conveying return currents. 

 Laws. There are three well-established 

 laws relating to electrolysis, as follows: 



1. The electrolytic action of the current is the 

 same at all parts of the circuit. 



2. The same quantity of electricity decom- 

 poses chemically equivalent quantities of differ- 

 ent electrolytes. 



3. The quantity of the electrolyte decomposed 

 in a given time is proportional to the strength 

 of the current. B.E.B. 



End of Volume Three 



