It consists of only two ingredients; phosphorus and water (pure not tap)
Step 1: Ingredients
To get the phosphor (the coating is a blend but this does not matter). I swished some distilled water in the light tube. It should be milky when you pour it out. I have yet to try different concentrations but I think the more phosphor the better.
Tap water is too conductive to use and ruins the effect. I used purified drinking water (less condutive than I thought)
Step 2: Product
I added some NaHCO3 to make it conductive hoping for a sweeter result, It made it worse.
The arc went through the liquid (like I thought but it did not show much arc). Perhaps making a channel of conductive mix and sending current through would be cool.
I hope to get a new ignition transformer for my Tesla to try really high voltage in a very large pool of fluid.