Combustion calorimeter with a decomposition vessel

A combustion calorimeter (1) comprising a housing and a decomposition vessel (2) within the housing, the interior space (3) of the decomposition vessel designed as a cylindrical reaction chamber by way of side walls and an upper sealing wall (5), and a mounting to which the side walls of the reaction chamber are adapted to be tightly sealed, the decomposition vessel (2) being replaceably arranged in the housing and comprising at least one temperature sensor (7) for measuring the temperature of the decomposition vessel (2), at least one second temperature sensor (8) being located on the inside of a wall region of the housing (6), and the decomposition vessel (2) being in an upright orientation in the housing (6) in a usage position, characterized in that the decomposition vessel (2) has a greater wall thickness in a region that is at the top in the usage position than in the lower region thereof, the wall thickness of the decomposition vessel (2) increases from the bottom to the top up to the region having the greatest wall thickness, and the increase in the wall thickness is steady and provided to be rectilinear, or curved in a convex shape, or curved in a concave shape, in the longitudinal section.