Collisional excitation calculation of HCl in CRL 2136. The population diagram of H³⁵Cl in Fig. 2 is fit by the models with varying gas temperature and density, and the goodness of the fit is presented in terms of the standard deviation. Line radiation transfer is included in the model with the column density over velocity 3 × 10¹⁴ cm^-2/(km s^-1), which is consistent with the observed velocity dispersion in the infrared.