Technikatörténeti szemle 19. (1992)

KÖNYVISMERTETÉS - Papers of the First „MINERALKONTOR” International Conference on the History of Chemistry and Chemical Industry (Veszprém, 12-16 August, 1991)

The tide of war turned in June 1794 when the French won their first victory by defeating the Austrians at Fleurus, in Belgium. The French used a new weapon, a captive balloon from which observers could see the positions of enemy troops and throw out messages to soldiers on the ground. The balloon was operated by the Corps d'Aerostiers, the world's first military air force, which was founded at the suggestion of Guyton, who had himself made two flights in a hydrogen balloon in 1784, a year after the first flights by the Montgolfier brothers' hot-air balloon and Charles's hydrogen balloon. For military use a hdyrogen balloon was essential, for it could stay inflated for much longer than a hot-air balloon. This created a problem in 1794, for balloons were normally filled with hydrogen generated by the action of sulphuric acid on zinc or iron and the Committee of Public Safety would not authorise the use of sulphuric acid. Hydrogen could, however, be made by another method, the decomposition of steam by redhot iron with ferroso-ferric oxide as the other product. Before the Revolution this reaction had been carried out only in the laboratory, but at the national ballooning school established in 1793 at Meudon, near Paris, a large-scale plant was developed. It consisted of a brick furnace about two metres high which was used to heat iron cylinders containing scrap iron through which steam passed. The perfection of this large-scale process in a very short time was a remarkable achievement for industrial chemistry, due mainly to two men, N. J. Conte, the director of the Meudon School, and J. M. J. Coutelle, who commanded the aerostiers in the field. Observation balloons were used on several occasions after Fleurus, but the need to build a hydrogen-generating furnace near the battlefield made them less suitable for mobile warfare, and the Corps d'Aerostiers was disbanded a few years later. Military balloons were not again used until the American Civil War in the 1860's, when mobile hydrogen generators were available. Most of the leading French chemists were among the scientists mobilised in 1794, but Lavoisier was not one of them. Lavoisier had been in prison since November 1793 and on 8 May 1794 he was guillotined after a summary trial by the Revolutionary Tribunal. His execution had nothing to do with his scientific activities. He died because before the Revolution he had been a member of the Tax Farm, a group of financiers who collected certain taxes for the royal government. Twenty-eight of them were guillotined that day, after being unjustly convicted of defrauding the nation. Five other members of the Academy of Sciences lost their lives during the Terror, two of them as well known as Lavoisier, namely J. S. BaUly, an astronomer who had been Director of the Academy, and the Marquis de Condorcet, a mathematician, who was its Secretary. Like Lavoisier, they all died for political, not scientific reasons. The arsenals, the shipyards and the victorious armies needed engineers, but none were being trained, because like most other educational institutions, the engineering colleges that existed in 1789 had closed down. At the end of 1794 the Convention founded the Ecole Polytechnique. The Greek prefix ,Poly', which means ,many\ emphasises that many kinds of technology were taught there. Previously, the various branches of civil and military engineering had been taught in separate colleges, some of them very small, but the Ecole Polytechnique started with three hundred students. They all took a two-year general course in physics, chemistry and mathematics, then spent a thud year on a specialised branch of