TRENTON, April 24---Believing that they may be able to recognize the bodies of Washington A. Roebling, 2d, and Stephen W. Blackwell, Trenton victims of the Titanic horror, among those recovered and taken to Halifax by the morgue ship, Karl G. Roebling, a relative of the former, and W. J. Bowman, a close friend of both families, left today for Nova Scotia.