The enthalpies of formation [Δ (g)] of tricyclo [8.2. 2.24, 7] hexadeca-1 (13), 2, 4 (16), 5, 7 (15), 10 (14), 11-heptaene (2, 1, 2-dehydro [2.2] paracyclophane or [2.2] paracyclophane-1- ene) and tricyclo [8.2. 2.24, 7] hexadeca-1 (13), 2, 4 (16), 5, 7 (15), 8, 10 (14), 11-octaene (3, 1, 2, 9, 10-dehydro [2.2] paracyclophane or [2.2] paracyclophane-1, 9-diene) have been determined by measuring their heats of combustion in a microcalorimeter and their heats ...