Ethanol과 Formic acid가 반응 후 평형에 도달하였을 때 30 ℃, 40 ℃, 50 ℃에서 전증기압을 측정하였고 Gas chromatograph를 이용하여 기상과 액상의 물 분율을 구하였다. 혼합물에 유기산이 존재하면 산이 기상에서 dimer와 trimer를 형성하므로 Lewis fugacity rule을 적용한‘Chemical’theory를 이용하여 modified fugacity coefficient를 구하였고 이로부터 non-random two-liquid（NRTL）식을 이용하여 활동도 계수와 기상의 몰 분율을 계산하였다. 이때 사용한 NRTL Parameter는 2성분 기액 평형 데이터로부터 구하였다.
이상의 실험과 계산으로 구한 기상의 몰 분율을 비교하여 비교적 양호한 일치를 보았다.

When the reaction between ethanol and formic acid reach its equilibrium, the total pressures were measured at 30 ℃, 40 ℃ and 50 ℃, and the compositions in the liquid and vapor phases were obtained by the gas chromatograph.
It was found that the presence of carboxylic acid in the mixture induced both dimerization and trimerization. Therefore the fugacity coefficients must be calculated from‘Chemical’theory which uses Lewis fugacity rule. From the values of the fugacity coefficients obtained, the activity coefficients and the mole fractions were calculated in turn through the non-random two-liquid （NRTL） equation. The parameters for the NRTL equation were obtained from the experimental data for the binary system.
The experimental data on the mole fraction of vapor phase were in a rather good agreement with the computed results.