Steve is close to the secret formula. Yes there is table salt in the solution, along with a small amount of isopropyl alcohol to retard any kinds of algae growth as these cables are sealed for ever.
What would be interesting is to get some copper plating solution (that they have at my previous employ) and make some cables out of that stuff, but then, they might actually work good.
These work pretty good, aside from the high resistance (low conductance), but do tend to take away that nice twinkle and space in the recording.
I also like the beverage suggestions.
Have a nice weekend.
Wayner