It shall be lawful for any alien, who, on the eighteenth day of June, one thousand eight hundred and twelve, resided, and has since continued to reside in this State, and who is a subject of any sovereign state, or nation at war with the United States, after having filed according to law, a declaration of his intention to become a citizen of the United States, to receive, hold and convey any lands and tenements within this Commonwealth not exceeding in quantity two hundred acres, nor in value twenty thousand dollars, as fully to all intents and purposes as a citizen of the United States can do.