Berthelot, Pierre Eugène Marcellin
Pierre Eugène Marcellin Berthelot (1827-1907), a French chemist known for his early work in thermochemistry and his invention of the bomb calorimeter. He devised methods for conducting chemical reactions within a closed chamber surrounded by water at a known temperature. From the rise in the temperature of the surrounding water at the conclusion of the reaction, the quantity of heat created by the reaction could be measured. Berthelot's experiments, which resulted in the invention of the calorimeter (from the Latin for heat-measure), were completed independently of those by Danish chemist Hans Thomsen (1826-1909).