Page 50 - Curriculum Visions Dynamic Book

(Below) Aluminium, so widely
used today, was still regarded as a precious metal and used for jewellery until the end of the 19th century, when Charles M. Hall (above right) and Paul-Louis-Toussaint Héroult (above left) invented a process
for recovering it from bauxite by electrochemical means. Now it is produced on a massive scale. As production increased, the price fell. In recent years, for example, it has proved cheaper to make beverage containers from aluminium than to make them from glass.
The modern metal age
Iron and steel dominated the 18th and 19th centuries. By the second half of the 19th century it was the
turn of the chemists to lead the way, in particular through the development of the periodic table of
the elements (see page 8). The periodic table put all of the known elements into a pattern and showed where there were elements still to find. Many of these elements were metals.
At this time, therefore, scientists knew about many metals, but most could not be extracted from their rocks on a large scale. Aluminium and magnesium were two of these metals. Aluminium is the most widespread metal in nature, but its use remained elusive because
of the complexity of extraction. Like alloy steel, the process for its manufacture needed electricity. The method was developed in 1886 by Charles M. Hall in the United States and by Paul-Louis-Toussaint Héroult in France. At first, the aluminium produced was still
the most expensive metal in the world, and it was even used for jewellery. However, with new electric processes to extract it from its ore, the price fell dramatically.
As a result, people began to look for new uses for a material that was light, strong, and did not rust. Today aluminium is one of the most commonly used metals.
With increasing understanding of the properties of metals, more and more of them have
been put to good use, most especially as alloying metals combined with more common and traditional metals such
as steel and aluminium. For example, titanium was, like aluminium, at first a curiosity rather than a practical metal. All this changed with the invention of a new way of extraction in 1950.
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