170 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
soda or soda lye for use in soap, soda ash or carbonate, for washing 
or glassmaking, and into chlorine bleaching materials. Chemical 
works operating these rather complicated chemical processes exist 
on an immense scale in all civilized countries; it 1s estimated that 
$50,000,000 is thus invested in Great Britain alone. The electrolytic 
alkali industry is barely 20 years old, yet it is already more than 
holding its own with the older chemical process, and advancing 
rapidly; 20 years more will probably see the older processes entirely 
superseded—they are at present fighting for their existence. As 
for the electrolytic process, the salt is simply dissolved in water 
and by the action of the current converted into caustic soda at one 
electrode and chlorine gas at the other. By some special devices 
these are kept separate and collected by themselves, and the work 
is done. The principles involved are simplicity itself as compared 
with the older chemical processes, the only agent consumed is electric 
energy, and the products are clean and pure. 
Chlorates.—These are salts used on matches and in gunpowder. 
Chlorate of potassium is a valuable salt with important uses. It is 
made from common cheap potassium 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 production 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 practi- 
cally entirely superseded it. 
Perchlorates.—These salts have more limited uses, but are made by 
expensive chemical methods. The electrolysis of a chlorate solution 
at a low temperature, without separating the products formed at the 
two electrodes, results in the direct and easy production of perchlo- 
rates. I cite this more to illustrate what I might call the versatility 
of the electrochemical 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 electro- 
lyzing melted caustic soda, and at this moment several large works 
are working his method on an immense scale. The caustic contains 
sodium, hydrogen, 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 adhered 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. 
