A regular Pray Tell reader who is also a chemist writes in with this important warning: Don’t use alcohol on salt for the Paschal fire!
This is just a version of a chemistry demonstration that is extraordinarily dangerous. The so-called rainbow demonstration has led to many serious injuries in onlookers and teachers. See this notice from the American Chemical Society,.
One of the dangers here is that vapors from the alcohol can travel out of the container and along the ground, then ignite in a ribbon of flame. Instructions from the Episcopal Altar Guild warn about the vapors escaping, but they don’t seem to realize the hazard this presents. See two versions of the instructions, here and here.