Infrared absorption by O3, NO, NO2, N2O, HNO3, CO, COS, CH4 and H20 have been observed from a balloon platform at 40 km of altitude and 44 ¿N latitude with a grille spectrometer. The resolution is, for the most part, better than 0.1 cm-1 An analysis is made of the causes of uncertainties. Height profiles are deduced for these species down to 20 km. The mixing ratios near 40 km are 8.5¿1.5 ppm for ozone, 8.5¿1 ppm for water vapor, and 19¿5 ppb for carbon monoxide. Nitric acid and carbonyl sulfide exhibit a decreasing profile with altitude. Mixing ratios near 30 km are <10-10 for COS and 8¿1 ppb for HNO3. Some common observations are made, related to the particular temperature profile, which emphasize the importance of simultaneous measurements of stratospheric species and meteorological parameters.