A British Contraband.
--A negro belonging to a British subject who had been stolen by some Yankees in Missouri, is the exciting topic in St. Louis now. The British Consul has taken the matter in hand, and Gen. Halleck promises him that the negro shall be surrendered to him if proved a British subject, and if not an effort will be made to show that Wheelan has violated his neutrality by encouraging the rebellion, and if he loses the negro the British Consul will afford him no assistance to recover the same.