ELECTROCHEMISTRY—RICHARDS. 169 
ii 
Electrolytic apparatus and processes use or utilize the separating 
or decomposing power of the electric current. Whenever an 
electric current is sent through a liquid material which is compound 
in its nature, i. e., a chemical compound, the current tends to decom- 
pose the compound into two constituents, appearing respectively 
at the two points of contact of the electric-conducting circuit with 
the liquid in question, i. e., at the surface or face of contact of the 
undecomposable conducting part of the circuit with the decompos- 
able part. If the current has a definite direction the constituents 
appear at definite electrodes. The action is simply the result of 
the current extracting (or tending to extract) from the electrolyte 
one of its constituents at each of the two electrode surfaces. All 
subsequent changes following upon this primary tendency of the 
current are called secondary reactions, and are practically simul- 
taneous with the primary. These may even be regarded as truly 
primary reactions also, the primitive decomposing or separating © 
power of the current passing being regarded only as a tendency 
or a determining cause which practically results in the reactions 
actually taking place. 
This agency is an extremely vigorous and potent force for produc- 
ing chemical transformations. It enables us, for instance, to split 
up some of the strongest chemical compounds into their elementary 
constituents, to convert cheap materials into much more valuable 
derivatives, to purify impure materials, in short, to perform easily 
some very difficult chemical operations and in some cases to perform 
chemical operations otherwise impossible. A description of all 
these various processes would take a volume, but a short explanation 
of a few of them will make the principles clear and suffice for my 
present purpose. 
Electrolysis of water—As a raw material, water may be said to 
cost nothing. Apply an electric current to it in the proper way, 
and it is resolved into its constituent gases, hydrogen and oxygen, 
as cleanly and perfectly as anyone could desire. These gases have 
many and various uses, and are valued each at several cents per 
pound. A whole industry has thus grown up, based on the simple 
electrolysis of water, to supply these two gases for various industrial 
uses. Europe possesses many of these plants; there are a few in 
the United States. The speaker has translated from the German 
a small treatise on this industry. 
Electrolysis of salt—Common salt, sodium chloride, is one of 
the cheapest of natural chemicals. It has some uses of its own, 
but centuries ago chemists and even alchemists devised chemical 
processes for transforming it into other sodium salts, such as caustic 
