It the same year, he recommended Takeaki ENOMOTO as a mission to conduct negotiations with Russia, and the acceptance of this recommendation meant that ENOMOTO played the role of concluding the negotiation of the Treaty of Saint Petersburg (Sakhalin-Chishima Exchange Treaty) as Envoy extraordinary.
この年、ロシアとの交渉にあたって黒田は榎本武揚を使節に推薦して容れられ、榎本が特命全権公使として樺太・千島交換条約の交渉と締結にあたった。