Magnesium is another metal which is produced solely by electrolysis. In this case the double salt of magnesium and potassium chloride is kept molten in an iron receptacle and is subjected to the passage of the electric current. Chlorine is liberated at the anode, and the magnesium, alone, separates at the cathode.
The magnesium is not much lighter than the molten bath so care must be taken that the melt be kept as dense as practicable. Other salts, such as barium chloride, may be added for this purpose. The details of the process of manufacture are guarded closely, although the normal cost of production is considerably under 80 cents a pound. The novice finds much difficulty in getting rid of the chlorine, in preparing easily the pure anhydrous salt to be used, in collecting the magnesium together from the bath in which it diffuses, etc.
Unlike sodium, magnesium has uses for its own metallic properties. It is the lightest of the available metals and makes alloys which are strong and tough. With the increase of aviation there certainly will be greater demand for this metal.
Another use for reasonably cheap magnesium metal would be in deoxidizing other metals. Magnesium quickly combines with oxygen as found in molten steel or in other alloys, and would be used far more extensively if the price permitted. It is astonishing from the metallurgical point of view that, with magnesium compounds so abundant and with the metal presumably separated with no undue difficulty, the price could mount to $5 a pound and remain there for an entire year, as happened during 1915.