when you precipitate the gold powder from the first dissolution, it will still be contaminated due to a process called "drag down". it is a physical process that happens near the end of the precipitation where the gold will "drag down" base metal from solution as it precipitates. decant solution down to the powder.add water to the powder to fill half the container. bring this to a boil, this will dissolve any water soluble salts. boil for a few minutes and let the solution cool. decant down to the powder. repeat this rinse. next add water to one quarter of the container and add to the water fresh hcl to complete one half fill of the container. bring this to a boil, continue to boil for 15-30 minutes. do not allow to boil dry. remove heat and allow to cool. decant down to the powder. if the hcl discolored on the first boil, repeat until the boil stays clear.next rinse with water, bring to a boil, remove the heat and allow to cool. repeat this rinse. next, add ammonium hydroxide and water 50/50 to fill half the container and bring to a boil. this is to remove certain salts and traces of silver chloride. remove heat and allow to cool and decant to powder. next, follow with 2 water rinses and 1 hcl rinse followed by 1 water rinse.
i know it sounds like a lot to do. but think about it this way, how pure do you want your gold and how much are you willing to do to get it pure.