In search of aluminum
Humankind has utilized a variety of aluminum compounds since ancient times. Around 5,000 BC, the skilful potters of southwest Asia, now Iraq, made pots from compounds of clay and aluminum. In ancient Egypt and Babylon, aluminum compounds were likewise used to make chemicals and medicines. Roman natural historian and author Pliny, born in 23 AD, wrote about alum - the salt containing aluminum, potassium, sulfates and water of crystallization, which was used from antiquity to the Middle Ages as a mordant to fix dye in weaving. By the early 18th century it was considered possible that alumina (aluminum oxide), which is found in clay and elsewhere, could be processed to yield metal. But isolating the aluminum turned out to be an extremely difficult process and was not accomplished before the beginning of the 19th century.
The British chemist Humphry Davy came to the conclusion in 1807 that alumina was a compound of oxygen and an unidentified metal that he named "aluminum". Davy made extensive experiments aiming to break down the compound by electrolysis, using electrical cells. He did not succeed in producing pure aluminum, but was able to prepare an aluminum mixture.
In 1825 the Danish physicist and chemist Hans Christian Ørsted was the first scientist to succeed in isolating aluminum. He dissolved aluminum chloride in a mixture of mercury and metallic potassium, and after removing the mercury by distillation he obtained a pea-sized granule of aluminum.
Encouraged by Ørsted's success, German physicist Frederich Wöhler continued experimentation and in 1827 found a way to process aluminum from aluminum chloride with metallic potassium, without using mercury.
The Frenchman Sainte-Claire Deville improved Wöhler's method in 1854 by using sodium instead of potassium. Over a period of 35 years he produced 200 tons of aluminum and succeeded in reducing the processing cost 100-fold.
Aluminum was first shown to the public at the World Fair in Paris in 1855, where it kindled tremendous interest.
The Frenchman Paul Héroult and the American Charles Hall (see picture) separately applied for aluminum production patents in 1886. Both used the method of dissolving alumina in molten cryolite before extracting the aluminum by electrolysis. Around the same time, Siemens invented the electric generator in Germany while Karl Josef Bayer in Austria realized a method for processing alumina from bauxite. The foundation for processing aluminum from alumina by electrolysis was laid. The global ascent of aluminum had begun.