The Romance of Modern Chemistry

CHEMISTRY AND ELECTRICITY accompanies it in the natural state. The mineral which is used in this country as a source of alumina is “bauxite,” obtainable in large quantities in the south- east of France. When pure alumina has been prepared from bauxite it is dissolved in a bath of molten cryolite—a Greenland mineral—and subjected to the decomposing action of an electric current. Electrolysis takes place quietly at a temperature of about 1500° Fahrenheit, with the result that the aluminium from the alumina is separated at the cathode, and the oxygen goes to the anode. The latter is made of carbon, and at the comparatively high tem- perature which prevails, it combines with the oxygen from the alumina, and passes away as gaseous carbon monoxide. The metal, on the other hand, collects at the bottom of the bath in the molten condition, and is run off from time to time. There are some very interesting points about the production of aluminium in this country. As already stated, the raw materials of the industry, the bauxite and the cryolite, are obtained from France and Greenland respectively ; the bauxite is purified in Ireland (where also, by the way, this mineral is to be found), while the actual production of the metal is carried on in some of the most outlying parts of Great Britain. We usually associate metallurgical processes, such as tin- and iron-smelting, with busy centres of population, and it may seem strange that in order to find aluminium works we must go to the remote Scottish Highlands. For this curious circum- stance, however, there is a very sufficient explanation. Even the non-technical reader will perceive that in order to produce aluminium cheaply, it is absolutely necessary to have inexpensive power for the dynamos 300