The heats of combustion in oxygen at 25°C of liquid di-n-butylether, di-sec-butylether, dipropylether and di-iso-propylether were measured using conventional bomb calorimetry. The standard heats of formation of the ethers were derived from the measured combustion heats (values in kcal/mole), viz., AH; (nBu20, Ziq) = -90-34f0-24 ; AH? (nPr20, Ziq) = -78-59f0.21 ; AH; (sBuaO, Ziq) = -95.98 +Ow27 ; AH; (iPr20, Ziq) = -884.01 f0.34.Pilcher and co-workers,l-3 using the flame calorimetric technique, have measured the heats of combustion of a number of low-boiling ethers and oxygen-ring compounds. The flame calorimeter is well-suited to studies on volatile compounds (b.p.