Vitriol

As a chemical/biological nerd, I really like this word I randomly stumbled upon. I'll work backwards through the definitions. According to the AHD, the everyday use of this would would be to describe a "bitterly abusive feeling or expression." This ties in with it's first definition. Vitriol is a common name for sulfuric acid. So a bitter remark is like throwing acid at the person. Cute, no?
But sulfuric acid is not the only substance that the name vitriol originally covered. Vitriols compose an entire subset of chemicals based off of mineral sulfate groups, such as zinc sulfate, copper (II) sulfate, iron (II) sulfate, ect. These salts were called vitriol because of their glass-like appearance. This, in turn, leads to the words etymological definition: glass(1). From Latin vitrum (glass), we got vitreus, which in turn became vitreolum in late Latin(1). Medival Latin turned the word into vitriolum, from where the old French and Middle English took the word(1). During the Middle Ages, this word was then applied to all the salts, and in the 8th century sulfuric acid was created(2). It gained the name vitriol (or oil of vitriol/spirit of vitriol), and from there it entred into everyday language was a way to describe an "acidic" remark(2). Interesting!

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1- AHD
2-http://en.wikipedia.org/wiki/Vitriol