There was a mining tradition for many centuries in Europe, in which rock was heated with fire and then shattered, or at last weakened, by pouring on large amounts of vinegar. Hannibal was said to have used this method to create roadways large enough for his war elephants when crossing the Alps to invade Rome in 218 BCE. Modern chemistry doesn't explain this, and surely the smell of vinegar steam must have been a dissuasive experience. My colleague, Mining Guide Philippe Dozolme, goes into the history of this custom and favors the explanation that the whole thing was based on a transcription error in an ancient manuscript. It wouldn't be the first time something like that has happened.