The description of the Ark of the Covenant fits as a Leyden jar like device. Mythbusters episode supports this.
As we are digressing into mythical devices, I always thought that the Ark of the Covenant might be an Orgone generator that actually works. Ha! Some similarities in published designs between the two devices except that as far as I know, no-one has ever sprung for gold sheeting to line the wood when trying to build an Orgone generator.
Or, you know, a container to store and carry some old stone tablets.
However, I can personally attest that the shock from an approximately one gallon Leydon jar fashioned from an old chemical bottle and Al foil is something not to be repeated. Also one gets a nasty burn at the point of entry of the juice which is perhaps a secondary consideration.