We have investigated the vacuum ultraviolet (VUV) emissivity of a cascade arc in argon from 125 to 200 nm. The temperature and pressure dependences of this emissivity are the subject of this paper. Enhancement of the emissivity has been obtained by adding nitrogen to the argon. In some wavelength ranges, the increase of the emissivity due to broadened lines is more than a factor of 10 in a spectral range of several nanometers. These lines reach the blackbody limit, corresponding to the electron temperature of the plasma inside the arc. The electron temperature has been varied between 12,200 and 14,500 K. The relative temperature dependence of the free-bound Biberman factor as a function of wavelength in this temperature range has been determined from continuum measurements and compared to the theoretical temperature dependence of the free-bound Biberman factors according to Hofsaess. The agreement is good.