Just think...back in the day all those alchemists really did have it all wrong. Go figure. Hey Doc...I heard someplace that the digestive juices inside the stomach are more powerful then the best corrosive acid. Is that true? "Cause if it is...(secret behind the starkerbark...shhhh...don't tell no one).
Nope...most corrosive liquid?
If you mean corrosive to inorganic elements, probably sulfuric acid.
As far as human flesh goes, there is no question that HF (hydrogen fluoride / hydrofluoric acid) is the most corrosive.
First, HF causes no painful burns on contact which allows it to seep deeply into human tissue without notice. It may take hours for HF exposure to become apparent.
The fluoride cation combines with the calcium in bones to dissociate calcium, causing the bones to essentially slowly liquefy. Local skin, muscle and fat necrosis follows soon after.
Starkers ate a book once and it desolved. We called it readers digest.
"Reader's Digest Vaporized Edition"....lol. 
