As for browning solutions, this would have to be one of my favourites;

Spirit of Nitre, 3/4 Oz
Tincture of Steel, (?) Oz
Black Brimstone, 1/4 Oz
Blue Vitriol, 1/2 Oz
Corrosive Sublimate, 1/4 Oz
Nitric Acid, 1 Drachm
Copperas, 1/4 Oz
Water 1 1/2 pints
Mix well and bottle

I couldn't find anything to say that it had to be done in a cemetary or on a full moon but I imagine reading Shakespeare while waiting for it to settle wouldn't go amiss.