Antoine Lavoisier, who proposed in 1789 that measuring both heat and carbon dioxide content could shed light onto an organism’s internal processes of metabolism. Lavoisier and Pierre-Simon Laplace constructed the first iteration of the calorimeter, scaled for a guinea pig. In their contraption, the guinea pig was enclosed in an internal chamber, with a surrounding chamber of melting ice to measure the heat from the animal’s internal combustion (Carpenter 2003). Because Lavoisier’s calorimeter measured heat directly, the technology came to be known as direct calorimetry (as opposed to indirect calorimetry, where oxygen and carbon dioxide exchanges are measured as proxies for heat).
