Look it up, I was a lazy kid back then, so I didn't check. NaCl melts at 800 C. A propane torch gives a flame at some temperature range. I used two because, 1). I had two, and 2.) I wanted heat from above and below, so heat couldn't radiate away. My whole setup is dumb, for 3 different reasons, if you consider the danger of a 12 year old possessing free elemental sodium as one of them. See if NaOH has a low enough melting point, or if yo can get a hotter torch -- keeping the discussion, purely theoretical, of course.