Re: Aqua regia

It is interesting that gold does not react with anhydrous chlorine gass
even at very high temperatures. Bubling chlorine gas through molten
gold is the method of choice for removing trace impurities, namely
silver and copper (their chlorides float on top of the melt.

Also, have you noticed that pure gold is rather orange-yellow
(especialy as a spongy cake made by high current electrolytic
purification)? Just check one of your gold bricks or pure gold coins.
Most of what is considered a gold color is actualy color of gold alloys
with silver. And adding copper does not make gold look more golden,
just pink.

.

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