Louis Kossuth, having been set at liberty by the Turkish government, will very soon arrive in the United States, where extraordinary demonstrations of respect will be offered to him in several of the principal cities. About nine months ago Kossuth committed to the care of Mr. Frank Taylor, a young American visiting Broussa, the MS. of an address to the people of this country, which was published in a translation, at New-York, on the 18th of October--having been withheld until that time lest its earlier appearance should affect injuriously the interests of its author in Europe. The friends of liberty will rejoice that Kossuth is free, and in a land of liberty; but it is not improbable that future events will demonstrate, that the Austrian government was not altogether unreasonable in protesting against his enlargement. Kossuth and Mazzini are scarcely less terrible to tyrants, as writers, than as the leaders of armies and the masters of cabinets. Although extraordinary prosperity in a state may sometimes lead to arrogance and injustice, the position of this country toward several European powers who intimate an intention of compelling a certain policy on our part in regard to Spain, must insure a triumphant consideration of the _Union_, in which we have a strength that may laugh their leagues to scorn. The details of an arrangement between Spain, France, and Great Britain, are not yet perfectly understood in the United States, but it is generally known that some plan has been adopted which will be likely to draw from the Secretary of State a sequel to his letter to Mr. Hulseman, the Austrian _chargé d'Affaires_, whose experiences were made known a year ago. The vessels of the American exploring expedition in search of Sir John Franklin returned--the _Advance_ on the 30th of September, and the _Rescue_, which had separated from her on the banks of Newfoundland, a few days after. It is probable that a full account of this heroic enterprise, so honorable to its authors and to all engaged in it, will soon be given to the public, by Dr. Kane, or one of the other officers; and as any such brief statement as we could present of its history would be unsatisfactory, we shall not now go further into details than to say no traces of Sir John Franklin, except such as we have already noticed, were discovered, and that the crews came home after a year's absence in excellent health. The nearly simultaneous return of the British expedition has caused considerable discussion in England. It appears to be felt very generally that it is not justifiable to abandon the pursuit until the fate of Sir John Franklin has been demonstrated by actual observation. Such satisfaction is due to science and to humanity. Proposals are now, we believe, before the Admiralty, for sending into the Arctic seas one or more steamers, with which alone the search can be advantageously prosecuted further.