Jurisdiction — Exemptions from — Foreign States — Money Belonging to One Sovereign Wrongly or Mistakenly Transferred to Defendant Servant of Another Foreign Sovereign — Action to Recover Money — Whether Foreign Sovereign, Not a Party to Proceedings, Is Impleaded — General Scope of Doctrine of Immunity — Whether Applicable to Moneys Said to be Held on Trust — Applicability of Immunity to a Debt or Chose in Action — Relevance of Possession and Control.