New measurements of homogeneous nucleation onset data for argon and nitrogen from the cryogenic
nucleation pulse chamber have been performed. By reducing the amount of carrier gas in the gas mixture, higher onset pressures and temperatures could be reached. The new results are consistent with older data from the same apparatus and literature data. Carrier gas-free experiments with nitrogen show no associative effects. Interestingly, the classical nucleation theory predicts the onset results of nitrogen more accurately than those of argon, despite argon being the more ideal substance of the two.