A self-packing steel combustion bomb with internal volume of 0.3 dm3 was utilized for burning the examined compounds placed in a thin-walled quartz crucible. Before each experiment the combustion bomb was flushed with oxygen for several minutes and immersed in a calorimetric vessel containing 4.6 kg of water. Themass of the calorimetric vessel was measured with accuracy to within 0.5 104 kg.