Update: The stone ferments very well by being melted with pure silver nitrate crystals. The quantity needed is 1/4 part silver nitrate to 1 part stone. Adding too much silver nitrate is not a problem,until you reach 20 parts silver nitrate to one part stone, it is wasteful to use that much because it no longer dissolves in water and you're left with a white powder on the bottom of your flask (probably silver chloride).
On a side note: I tried one drop of the elixir without silver and one with to compare their strength, and I found out something. It turns out that in terms of psychic energy, the elixir without silver reaches a higher voltage much faster than the one with. The one that has silver in it has a drastically higher capacity for psychic energy so it doesn't reach as high of voltage potential as quickly,but it has a whole lot more amps when it gets there,and releases it's energy over a slightly longer time span.
This would explain why the stone loses charge when fermented, and also why the masters chose to first create the stone,then ferment only a tiny portion,then multiply it by imbibing it with something charged to a higher potential.
My advice is that you should use prudence when sampling your elixirs or you may be in for an unpleasant jolt of psychic energy.