Today (yesterday but I was too busy to login) I learned that "vitriol" is an archaic name for sulfuric acid (H2SO4*). So the expression "spraying vitriol" at someone didn't originally mean "saying something nasty to them," it was about a literal acid attack. Learned this from a youtube documentary on the subject, not gonna link because it's a pretty horrible topic with some pretty horrible graphics, but it puts the whole linguistic thing in a different light.
*A limerick from my 7th grade science teacher:
Johnny was a chemist
But Johnny is no more
What Johnny thought was H2O
Was H2SO4