BERTHELOT, brietlti, PIERRE EUGENE MAR. CELLIN 1827—) . A French chemist. Ile was born in Paris. He received his education at the College Henri IV. and devoted himself to research in organic chemistry. In 1854 he re ceived his doctor's degree in science, on present ing a remarkable thesis giving an account of his artificial reproduction of natural fats. The fact that fats are mixtures of glycerides, i.e. compounds of glycerin with the so-called fatty acids. had been known since 1823, when Chev reul effected the decomposition of fats into their chemical constituents. Berthelot, however, was the first to produce those important organic products synthetically. In the same thesis he showed that glycerin, which is capable of com bining with three equivalents of a monobasic acid, is an alcohol; and thus the idea of poly atomic alcohols was first introduced into chem istry. A large number of diatomic, triatomic in general, polyatomie alcohols, have since been prepared, and form an important class of organic compounds. (See ALeonor.s.) In 1851 Berthe lot became assistant to Balard at the College de France; in 1860 he was made professor of or ganic chemistry at the Ecole de Pharmacie, and in 1865 a new chair of chemistry was founded for him at the College de France, where be has since lectured on theoretical chemistry. In 1873 he was elected member of the Institute, and in 1889 perpetual secretary of the Academy of Sci ences. in 1876 he was made inspector-general of higher education; in 1881 a lifelong member of the Senate; in 1886-87 he was .Minister of Public Instruction and in 1895-96 Minister of Foreign Affairs.
Berthelot is one of the most brilliant ex perimental chemists of our time. One of the pio neers of organic synthesis, he has contributed to our knowledge of almost every class of carbon compounds, and the importance of his experi mental researches on explosives and dyestuffs cannot be overestimated. De also furnished an
immense number of experimental data concern ing the phenomena of heat, which accompany chemical transformations, and the science of ther mochemistry is largely based on his observations, although his theoretical Interpretation of those phenomena has been proved to be erroneous. Ac cording to Berthelot, the heat evolved during a chemical reaction measures the power that causes the reaction. It has, however, been proved. both theoretically and experimentally, that while this principle holds good in many cases, it is by no means a general law, "a third principle of thermodynamics." as Berthelot still claims it to he. Berthelot's published works include: Chimir organique fonder sue in synthrse (2 vols., 1860) Le•ons sue les peineipes sneres (1862); Leeons sur les inerhodes de synthese (1864); Leptis sur l'isomerie (1865) ; Trait(' elementaire de ehimie organique (1st ed. 1872; 2d ed., with Jungileisch, 2 vols., 1881) ; Sue in force dr lit poudre et les matirees explosires (1871, 1872, and 2 vols. 1883) ; Verification de Pareomrtre de Banme (1873) ; La synthesr chimique (1875); Essai de meeanique chimique fondee stir la thee mochimie (2 vols., 1879) ; Les origines de l'alchimie (1885); Collection des anciens elamistes grecs (2 vols., 1887) ; La ehimie an moyen age (3 vols.. 1893) ; Traite pratique de calorimetric ehimique (1893). Ile also published a large number of papers on various scientific topics, in the Comptes rendus de l'Academie (les Sciences and in the Annales dr chimie of de physique. For his life, consult the Popular Sci ence Monthly, Max', 1SS5.