For dry air at 1.0000 atm pressure, the densities at -50 degreesC, 0 degrees C, and 69 degrees C are 1.5826 g dm-3, 1.2929 g dm-3, and 1.0322 g dm-3, respectively. From these data, and assuming that air obeys Charles's law, determine a value for the absolute zero of temperature in degrees Celsius.