Re: What chemicals are in highlighters?

The exact contents are almost always covered by patent, but I can give 
you some general answers.

The chemical that makes the glow is just a fluorescent pigment, like 
Basic Yellow 40, or Acid Blue 9; sometimes a compound called an optical 
brightener is added to increase the fluorescence. The pigment is usually 
mixed with water and a cosolvent, like dipropylene glycol or glycerol, 
and sometimes surfactants or viscosity agents so that it flows (or 
doesn't) as desired. The ink mixture flows through the fiber tip of the 
marker.

Reviving it with alcohol did exactly what you surmised -- you just 
diluted whatever was left and extracted whatever remained in the tip.