The coin purse looks only large enough to hold maybe 10 or 15 coins at the most. It's quite small and easy to conceal.

You start to add your coins into your new coin purse, and... they disappear!

You hear the sound of clinking coins, and all your coins appear in the chest.

Experimentation reveals that the coin purse allows you to place and withdraw coins from the chest; however, while you are able to store other very small items in it, you're not able to transfer any other objects through the purse.