Three blnary systems of dl-n-butyl ether with I-chloropentane, 1,24lchloroethane, and l,l,l-trlchbroethane were Investigated flrst In a dynamic stlll, second In a flow calorimeter, and thlrd In a denslmeter. Vapor-llquW equlllbrla (VLE), excess enthalpies ( h e ) , and excess volumes ( v E ) are reported at temperatures In the range of 283-370 K. With the results of the experiments, parameters of several "popular" expressions for the excess Gibbs energy are fitted with varlous fltUng procedures. None o f the gc models and none of the fitting procedures Is clearly superior to the others.