What’s going on in this cool time-lapse video from Italian YouTuber wwwperiodictableru isn’t a chemical reaction in a formal sense. It’s not oxidation or some other type of traditional corrosion. Turns out metallic or “white” tin spontaneously changes its so-called beta crystal structure at temperatures below 13 C to the crumbly alpha structure of “grey” tin. It’s the same stuff before and after–just different allotropes of the same element. The transformation, known as “tin pest” (Wikipedia), catalyzes itself–once it starts it just gets faster and faster.

There is a popular, if scientifically dubious, story that blames part of the failure of Napoleon’s infamous Russian campaign on the fact that the buttons on his soldiers’ coats were made of white tin, which was fine in Europe, but decayed into useless gray tin in the brutal cold of the Russian winter, and thereby prevented them from properly buttoning their coats. Implausible for lots of reasons, it turns out, but still a good yarn.

[Thanks, William Beaty!]