Quote Originally Posted by ME Super View Post
Be careful when working with Nitric Acid that you do not spill any on your skin. It reacts with an amino acid in your skin to form a yellow dye that's much the same color as a yellow highlighter. My college chemistry professor called this "dinitroskin." Your skin may get hard where this happens, but fortunately it only gets the top layer of your skin. Nitric acid will burn you if you don't rinse it off right away (but the yellow compound will have already formed by this time).
From Wikipaedia: TNT [of which nitric acid is a constituent] is poisonous, and skin contact can cause skin irritation, causing the skin to turn a bright yellow-orange color. During the First World War, munition workers who handled the chemical found that their skin turned bright yellow, which resulted in their acquiring the nickname "canary girls" or simply "canaries."

A useless piece of information I learned during a visit to the Royal Gunpowder Mills at Waltham Abbey last week! It promotes itself as 'Secret Island' to attract the kids, but if you get past that (or not!) there's a fascinating amount of history there. Well worth a visit.