a combustion vessel;

a thermally insulated bucket having an internal volume for receiving said combustion vessel, wherein said bucket can be filled with a fluid at a predetermined temperature, said bucket including a baffle into which said combustion vessel is positioned during an analysis;

an impeller rotatably positioned at a lower end of said baffle for circulating fluid around said combustion vessel during an analysis, said impeller coupled to permanent magnets positioned within said bucket;

a magnetic stirrer including permanent magnets positioned within said jacket external to said bucket for actuating said impeller through the magnetic coupling between the respective permanent magnets;

a movable cover selectively coupled to said combustion vessel and including an inflatable seal selectively coupled to a source of pressurized fluid for sealably engaging said bucket for sealing said bucket during an analysis including the combustion of a sample within said combustion vessel; and

wherein said cover includes one of a socket and post and said combustion vessel includes the other of a post and socket wherein said combustion vessel can be removably mounted to said cover by inserting said post into said socket.