>Anyone on the list know a recipe for making silver nitrate? Perhaps a
>reference book? I've heard photographers in the 1800's used to make silver
>emulsions by dissolving silver coins in nitrate acid in order to obtain the
>silver nitrate. Does it precipitate out? How do you concentrate/purify it,
>etc. ?
"Silver" coins (US coins minted prior to 1964 - since then they're mostly
copper) are an alloy of silver and copper, so if you dissolve them in
nitric acid you will get silver nitrate and copper nitrate. Unfortunately,
both of these are very soluble compounds, and separation is very difficult.
Inasmuch as coins prior to 1964 are also more expensive than an equal
weight of metallic silver, you should get silver from a company like Handy
& Harman, etc. To dissolve it (without waiting hours) you need to heat the
nitric acid (VERY dangerous) and feed the silver into it until no more
silver dissolves. If you then heat or desiccate the liquid, you will have
silver nitrate, which is very soluble.
> Eventually i'd like to dig out some silver ore (I know a locale), dissolve
>the rock, extract the silver, form the silver nitrate,
Depends on the compound of silver in the ore. If it's silver sulfide, you
will get poisonous hydrogen sulfide gas as it dissolves. If it's silver
oxide, you will almost have to boil the nitric acid to get the silver
compound to dissolve. Silver sulfate won't dissolve at all, and must be
calcined with charcoal (or equivalent) to extract the silver, which can
then be dissolved.
It's much less expensive (and safer) to buy the silver nitrate crystals! I
know the challenge is there, so it's your decision.
Sil Horwitz, FPSA
Technical Editor, PSA Journal
silh@iag.net