At the age of 26, around the time he was elected to the Academy of Sciences, Lavoisier bought a share in the Ferme générale, a tax farming financial company which advanced the estimated tax revenue to the royal government in return for the right to collect the taxes. On behalf of the Ferme générale Lavoisier commissioned the building of a wall around Paris so that customs duties could be collected from those transporting goods into and out of the city. His participation in the collection of its taxes did not help his reputation when the Reign of Terror began in France, as taxes and poor government reform were the primary motivators during the French Revolution.
Lavoisier consolidated his social and economic position when, in 1771 at age 28, he married Marie-Anne Pierrette Paulze, the 13-year-old daughter of a senior member of the Ferme générale. She was to play an important part in Lavoisiers scientific career—notably, she translated English documents for him, including Richard Kirwans Essay on Phlogiston and Joseph Priestleys research. In addition, she assisted him in the laboratory and created many sketches and carved engravings of the laboratory instruments used by Lavoisier and his colleagues for their scientific works. Madame Lavoisier edited and published Antoines memoirs (whether any English translations of those memoirs have survived is unknown as of today) and hosted parties at which eminent scientists discussed ideas and problems related to chemistry.
A portrait of Antoine and Marie-Anne Lavoisier was painted by the famed artist Jacques-Louis David. Completed in 1788 on the eve of the Revolution, the painting was denied a customary public display at the Paris Salon for fear that it might inflame anti-aristocratic passions.
For three years following his entry into the Ferme générale, Lavoisiers scientific activity diminished somewhat, for much of his time was taken up with official Ferme générale' business. He did, however, present one important memoir to the Academy of Sciences during this period, on the supposed conversion of water into earth by evaporation. By a very precise quantitative experiment, Lavoisier showed that the "earthy" sediment produced after long-continued reflux heating of water in a glass vessel was not due to a conversion of the water into earth but rather to the gradual disintegration of the inside of the glass vessel produced by the boiling water. He also attempted to introduce reforms in the French monetary and taxation system to help the peasants.