Pyrrole, pyrrolidine, pyridine and 2-methylpyridine were purified to approximately 99.9 mole % purity. Precautions necessary in the purification of these nitrogen compounds are described, including protection from water and oxygen. Boiling points, freezing points, densities, viscosities, surface tensions and refractive indices were determined on each of the compounds. Derived functions, including refractivity intercept, specific dispersion, molecular refraction, parachor and molecular volume were calculated. Mass, infrared and ultraviolet spectra of the compounds were determined. The stability of the compounds under storage was investigated, so that they could be used as calibration standards.