> > > > > a substance doesn't have to be an acid to be caustic > > > > Actually, a substance can't be both acid and caustic. > > Indeed - caustic refers to an alkali ! rather the opposite, > so to speak, of > an acid ;-) Ah contraire! caus·tic (kô'st?k) adj. Capable of burning, corroding, dissolving, or eating away by chemical action. Corrosive and bitingly trenchant; cutting. See synonyms at sarcastic. Causing a burning or stinging sensation, as from intense emotion: “Most of all, there is caustic shame for my own stupidity” (Scott Turow). n. > > Fortunately, capsacin > is neither. Fortunately. Probably wouldn't care for it was much if it were. ;-) Riley