A theory has it that the part of Québec's territory situated between New Québec and the height of land between the Hudson Bay and the St. Lawrence River basins belonged to the Hudson's Bay Company when the Québec Act was adopted in 1774 and that it was not added to Québec until 1898, and then only as a province of Canada. As a consequence, in the event of secession, Québec would relinquish any claim to this part of its present territory. The purpose of this paper is to demonstrate, in light of the settlement of a dispute relating to the northern boundary of Ontario in the XIXth century, that the area in question was really part of the Province of Québec under the terms of delimitation of the Québec Act.