"Things You Wouldn't Know If We Didn't Blog Intermittently."
A very cool reaction to watch, but definitely on the "don't try this at home, or probably ever" list. The substance being burned is Mercury(II) thiocyanate, and the reaction products include mercury vapor, cyanide gas, and sulfuric acid. Each of which us highly toxic in its own right.
There was a firework we'd buy that was like this. Very amusing.
I also used to get these from the fireworks stand when I was a kid. They were simply called Snakes. Don't they make them anymore?