Tin pest
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Tin pest is an example of an allotropic transformation of the element tin, which causes deterioration of tin objects at low temperatures.
Tin pest has also been called tin disease, or tin leprosy (Lèpre d'etain).
It was long observed in pipes in pipe organs in medieval in cathedrals in Europe in cool climates. What the medieval church members noticed, was as soon as the tin began decomposing, the process sped up, and seemed to feed on itself, and would continue even at higher temperatures.
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The allotropic transformation
At 13.2 Celsius (about 56 degrees Fahrenheit) and cooler, pure tin had a habit of self-destructing from the (silvery, ductile) allotrope of β-modification white tin to brittle, α-modification grey tin. Eventually it often decomposed into powder, hence the name tin pest.
What was happening was the decomposition was catalyzing itself, which was why the reaction seemed to speed up once it started; the mere presence of tin pest led to more tin pest. Tin objects at low temperatures would simply disintegrate.
A historical question of tin pest and the exploration of Antarctica
In 1910 Captain Robert Scott, the British polar explorer, set out on an expedition to the South Pole, then unknown. They trudged through the frozen deserts of the Antarctic, having left behind caches of food and kerosene for the way back. In early 1912, they began returning, having learned that the Norwegian explorer Roald Amundsen had beaten them. When they hit their first cache, there was no kerosene; the cans — soldered with tin — were empty. They later died in the cold and blizzards, only eleven miles from a massive depot of supplies.
Not all blame tin pest; some say it was the poor quality soldering that caused it, and both lack of food and exposure in the blizzard are thought as more major factors. Old buildings in Antarctica have been investigated and old tin cans up to over eighty years old have been discovered, with the soldering in good condition. One source observes,
- The likely cause of death for Scott’s polar party was some combination of scurvy, gangrene, starvation, dehydration, and hypothermia.
Napoleon's buttons
In 1812, Napoleon invaded Russia, and the tin buttons his troops wore later fell to pieces in the Russian winter.
The modern world
In modern tin casting and plating, the tin is alloyed with small amounts of antimony or bismuth which prevent the decomposition. Silver, indium, and lead have also been used.
External links and references
- On Robert Scott's mission to the South Pole (http://www.wilderness.net/library/documents/glover.pdf)