In the 19th century, aluminum was more valuable than gold. But then, overnight, it almost devalued. Why this happened and what discovery balanced the ratio of precious metals, we will tell in our article.
Aluminum is the 13th element of the Periodic Table. It is a light paramagnetic metal, which is considered the most common of its kind, as well as the third most common among the chemical elements in the Earth’s crust. The mass concentration of aluminum in it reaches 8%. Silvery-white, easy to shape, cast, and machine. Aluminum has high thermal and electrical conductivity, as well as corrosion resistance due to the rapid formation of strong oxide films that protect the surface. Aluminum forms alloys with almost all metals. The most well-known combinations are copper and magnesium (duralumin) and silicon (silumin).
- Density — 2,712 kg/m3
- Enthalpy of melting — 390 kJ/kg
- Boiling point — 2,518.8 °C
- Enthalpy of evaporation — 10.53 MJ/kg
- Heat capacity — 897 J/kg·K
- High electrical conductivity, thermal conductivity, and reflective ability
- Weak paramagnetic
- Mohs hardness — 2.75.
- Does not react with classical oxidizing agents
- Easily reacts with HCl and H2SO4
- Practically not subject to corrosion (it is widely in demand in the modern industry)
- Acts as a reducing metal
- Easily reacts with simple substances.
Was it not for this set of amazing qualities that aluminum was valued higher than gold in the 19th century? A vivid historical example of this is a gift from the British to the Russian chemist Dmitry Ivanovich Mendeleev. In 1889, they presented him with analytical scales, the cups of which were made of gold and aluminum, which at that time was considered an incredible luxury.
Elite Metal of the Past
Rare items for the French imperial court were made from the first aluminum. Napoleon III was a famous lover of this metal. There is a legend that wanting to show his power, the emperor ordered a doublet for the receptions of diplomats with aluminum buttons – incredibly expensive at that time. During his lifetime, the first aluminum toy for the Crown Prince was made, inlaid with diamonds, emeralds, and corals.
The imperial family also used aluminum sets and cutlery. The right to eat with an aluminum spoon for the nobility was granted as a sign of special imperial attention and patronage. Napoleon III even replaced the bronze sculptures of eagles above the imperial banners with aluminum ones. But here the decisive factor was not only the material’s high cost but also its amazing lightness: the figure began to weigh 900 grams instead of 2.5 kilograms.
The Story of Discovery
The element’s name came from the Latin word “alumen,” which translates as “alum.” The riddle of the incredible popularity of aluminum has a rather prosaic answer – it practically does not exist in nature in its pure form. The low content of native aluminum in its pure form can be found in the mouth of a volcano or natural waters, but its concentration is still extremely small. The thing is that in nature it occurs mainly in the form of compounds. For example, bauxite (Al2O3 · H2O) with impurities of SiO2, Fe2O3, CaCO3, or corundum (Al2O3).
Aluminum compounds such as the double salt of aluminum and potassium – alum KAl (SO4) 2 • 12H2O – have been known since ancient times. The ancient Greek historian Herodotus mentions Egyptian alum as a valuable commodity. On the island of Lesbos, alum was produced from alunite. A detailed description of the substance called alumen can be found in the Natural History of the Roman Pliny the Elder. He reports that a form of aluminum is naturally found in the earth and calls it “salsugoterrae.” Pliny also noted that different substances are listed under the name alumen, but they are all characterized by a certain degree of astringency and are used in dyeing and medicine. Today, we are also familiar with the concept of burnt alum. This is a modern pharmaceutical – a powder that is used in dermatology.
Aluminum was first synthesized in 1825 in Denmark. Physicist Hans Ørsted reduced the chloride of this element with potassium amalgam when heated and isolated the metal. Later, this method was improved by German chemist Friedrich Wöhler. He reduced aluminum chloride to metal using pure metallic potassium and was the first to describe the properties of newly made aluminum. The excitement of our ancestors around this metal is quite understandable: it was a rarity obtained through experiments.
In 1854, aluminum was obtained by a semi-industrial method. Sainte-Claire Deville used the Wöhler method but replaced potassium with sodium, which made the production process safer. In 1855, at the Paris Exhibition, the scientist presented a ready-made metal ingot. But there is no limit to perfection, and in 1856 he also improved his method obtaining aluminum by the electrolysis of a melt of double salt of aluminum chloride-sodium.
However, despite the variety of methods for producing aluminum, before the advent of the industrial electrolytic method, it was still considered more expensive than gold. In Russia, it was called “silver from clay,” since alumina Al2O3 prevailed in the raw material composition. The industrial method of producing aluminum appeared only in 1886. Charles Hall and Paul Héroult independently developed a method for isolating aluminum by the electrolysis of Al2O3 melt in cryolite. Since then, the incredible popularity of aluminum as a rare and precious metal gradually began to fade. And today we use it in everyday life completely without reverence.
Today, aluminum is used in various areas of the heavy and light industry:
- As the reducing agent of rare metals from their oxides or halides
- In the production of steels as a strong deoxidizer
- As an additive to other alloys
- In the jewelry business
- In tableware
- In the food industry (E173 food additive)
- In the military industry
- In the rocket technology
Interestingly, despite the possible prevalence in nature and the earth’s crust, animals do not use aluminum in metabolism. It is considered a “dead” metal. And even though its toxic effect is not great, inorganic aluminum compounds remain in a dissolved state for a long time and can harm humans and warm-blooded animals. Including through drinking water.
The article is based on open sources.