Calorimeter
an instrument for measuring the quantity of heat which a body parts with or absorbs when its temperature sinks or rises through a certain number of degrees, or when it changes its condition. An ice-calorimeter was invented by Lavoisier and Laplace. It is now superseded by the mercury calorimeter of Favre and Silbermann, which is a very delicate instrument. It is essentially a thermometer with a very large bulb and a capillary tube.