_From a letter of the 27th of July._--Count de Vergennes observes on an opinion, which prevailed in America, respecting the friendly disposition of the powers of Europe towards the United States, that as yet, not one Court had taken the least step, which manifests their disposition towards the United States. That the Courts of Vienna and Petersburg, having assumed the character of mediators, cannot be too reserved. For by a different conduct they would become obnoxious to one or other of the belligerent powers, and lose the important and glorious part, with which they are intrusted. That it results from these observations, that the United States ought to look upon themselves as being still separated from all other powers; and that they have but one professed friend, which is France; and that the United States ought to rely principally upon their own resources. The Count de Vergennes observes, that he has talked circumstantially with Mr Adams on these subjects, who appeared to be satisfied with what had been done in favor of his country. That he had communicated to Mr Adams the preliminary overtures made by the two Imperial Courts, as well as the intended answer of his Most Christian Majesty. That the great or only difficulty concerns America. That France will do all in her power to remove that obstacle, upon which depends the activity of the mediation. That as soon as it shall be removed, or proved to be insurmountable, proper instructions will be forwarded to the Chevalier de la Luzerne, concerning the conduct, which the state of affairs will require from Congress. That the Court of France had received, with great satisfaction, information, that Congress were disposed to trust their interest to the two mediating powers. The Chevalier de la Luzerne is directed to inform Congress, that no use shall be made of this disposition, in the present state of affairs; and that it shall be communicated only when it can be done consistently with the dignity of the United States.