Measurements of the molar excess volumes VmE of the system benzene-cyclohexane have been made under atmospheric pressure at 298.15K

and the reliability of the results obtained has been checked by comparison with literature data. Experimental determinations of the excess volumes have also been carried out at 293.15K for the binary systems of cyclohexanone (x) with each of the four substances

benzene( I )

cyclohexanone(Ⅱ)

cyclopentane(Ⅲ)

and methylcyclopentane( Ⅳ ). The data obtained were fitted with the equation VmE = x(1-x) @i=0 Ai(1-2x)i. The coefficients A0

A1

A2 and A3 of the correlating equations for the four systems are respectively ( I ) -0.8440

-0.2589

-0.1654

-0.02286

(Ⅱ)0.7006

0.3833

0.2562

0.1700

(Ⅲ)-0.2055

0.2896

0.3806

0.2923 and(Ⅳ)- 0.1402

0.3740

0.3488

0.2692

with a residual standard deviation σ of about 0.002cm3mol-1 for each system. The measurements were made with the continuous dilution method

where the dilatometer and the calculation method were partly improved.