152 MODERN SCIENCE READER 



chloride, in solution in water, by simply electrolyzing the 

 solution without trying to separate the products forming 

 at the electrodes. It is a simpler operation than the pro- 

 duction of electrolytic alkali. Chlorate thus forms in the 

 warm solution, and is obtained by letting the solution cool 

 and the chlorate crystallize out. The ordinary chemical 

 manufacture of this salt was tedious and dangerous; the 

 electrolytic method has practically entirely superseded it. 



Per chlorates: These salts have more limited uses, but 

 are made by expensive chemical methods. The electrolysis 

 of a chlorate solution at a low temperature, without sepa- 

 rating the products formed at the two electrodes, results in 

 the direct and easy production of perchlorates. I cite this 

 more to illustrate what I might call the versatility of elec- 

 trochemical methods, rather than because of its commercial 

 importance. 



Metallic Sodium: The caustic soda produced from salt 

 can itself be electrolytically decomposed ; this is the easiest 

 way of producing metallic sodium. Sir Humphry Davy 

 discovered sodium by electrolyzing melted caustic soda and 

 at this moment several large works are working this method 

 on an immense scale. The caustic contains sodium, hydro- 

 gen, and oxygen, and the current simply liberates the 

 sodium as a molten metal and frees the other two as gases, 

 which escape into the air. The process is simplicity itself 

 when the exact conditions are known and rigidly ad- 

 hered to. Metallic sodium is a very useful material to the 

 chemist, and the electrolytic method produces it at probably 

 one fourth the cost of making it in any purely chemical 

 way. 



Magnesium: This is a wonderfully light metal, whose 

 chief use is in flash-light powders. Its compounds are 

 abundant in nature, but its manufacture by any other than 

 the electrolytic method is almost impracticable. The oper- 

 ation consists in simply passing the decomposing current 

 through a fused magnesium salt a chloride of magnesium 

 and potassium found in abundance in Germany. 



