Featured Jug, ancient China?

This is a reagent for checking the silver content in metal.If the alloy contains 50 percent or more silver, there will be a pronounced reaction.It seems that the chromium picrate quickly turns red.I don't know)).This is strange.Although there is a slight reaction to brass, but it is weaker and lasts much longer, and a slightly different reaction.And here the reagent immediately quickly turns red, as if silver

 

Í think that is the acid we call nitric acid. Brass also reacts to nitric acid.
I suggest you have it tested by someone who does it professionally.

 

Old farts like me use a black scratch "stone" and 18k gold acid. I scrape the silver-colored metal on the stone until there's enough to see easily. Drop on a bit of the acid. It tends to be easier to read. WHen applied to a silver scratch the metal turns blue-white and "curdles". Pure silver ( often silverplate) reacts almost immediately. Sterling takes longer and lower percentages take longer still. It'll just eat through brass or pewter . Silver acid tends to stop working properly and can be hard to read even when it does.

 

Here is the metal above after the chromic peak.

 

Well, you need to check the composition of the metal with a detector.