Cavalry skirmish in the southwest.
Chattanooga, Aug. 9.
--Cavalry skirmishes are constantly reported.
Last Monday, Scott's cavalry made a dash on four hundred Federal near Sparta, and pursued them till they came to a superior force, and then retreated, leaving the Yankees in possession of Sparta.
Federal deserters are constantly coming in, and report the Yankee army much demoralized, and say they will not fight with negroes.