Thermidor
i. e., the "Hot Month," formed, in the calendar of the first French Republic, the 11th month, and lasted from July 19 to Aug. 18. The 9th Thermidor of the Republican year 2 (July 27, 1794) is historically memorable as the date of Robespierre's fall, and the termination of the Reign of Terror.
The name Thermidorians was given to all those who took part in this fortunate coup d'état, but more particularly to those who were desirous of restoring the monarchy.
THERMO CHEMISTRY it could not long escape notice. In the majority of cases, there is a rise in temperature, or, in other words, heat is evolved, but in some cases, the temperature falls, or heat is absorbed. Reactions of the former type are known as exothermic, those of the latter as endothermic. The first law governing these thermal changes was formulated by Lavoisier and Laplace, who stated, as the result of their investigations, that: The amount of heat which is required to decompose a compound into its constituents is exactly equal to that which was evolved when the compound was formed from these constituents. A second law of even greater importance was discovered by Hess, who demonstrated that :
The heat evolved in a chemical reaction is the same whether it takes place in one or in several stages. For instance, carbon may be burned either to carbon monoxide or carbon dioxide, according to conditions. Carbon monoxide may be burned to carbon dioxide, so that in either case the final chemical change is from carbon to carbon dioxide. The above law (known as the "Constancy of the heat sum") is, as a matter of fact, a direct consequence of a wider law-the principle of the conservation of energybut it was worked out by Hess experimentally. Of recent years important progress has been made in this branch of science as the result of researches carried out by Julius Thomsen of Copenhagen, and Berthelot, the famous French chemist. Thomsen devised new apparatus for making thermo-chemical determinations, and collected a mass of thermochemical data whose value can scarcely be over-estimated. Berthelot also made improvements in apparatus, and his discoveries have resulted in a great ad-