A new technique requiring pressure measurements only is used to determ
ine accurately virial coefficients for n-butane in the temperature ran
ge 308.15-348.15 K at pressures up to 110 kPa. Second virial coefficie
nts obtained are in excellent agreement with literature values, demons
trating the efficacy of the method. Third virial coefficients are in r
easonable agreement with the only value reported in the literature.