How to deactivate antique percussion caps?

I collect firearms. Recently got a beautiful cased percussion pistol circa 1850 that came with a tin of original percussion caps. I believe these (mercury fulminate?) caps are unstable and possible quite dangerous to handle or store. They however are very rare and collectible. How to deactivate the explosive without destroying the cap? Soak in water? Alcohol?

squeezie_19992016-09-27T09:13:23Z

salt water 3 days

USAFisnumber12016-09-30T08:57:44Z

Oil.

Anonymous2016-09-25T16:23:04Z

Soak in oil. That is what I have read about it. I shoot BP pistols and rifles.