Interferometric observations of HCN (J=1-0) emission from the circumstellar envelopes of two enshrouded carbon stars have been performed. The two stars, AFGL 2233 and IRC+ 10401, are unusual because of their strong HCN emission and high outflow velocities. We find that the emission regions are relatively compact and that there is no evidence of asymmetry in these outflows. The emission region around AFGL 2233, a star which is believed to be at a larger distance than IRC +10401, was not resolved by a 5.9"×5.l" beam, although an undetected extended component may exist. The emission region of IRC+ 10401 was resolved by a 5.1"×4.6" beam, and we estimate a deconvolved source size of about 8.6". This indicates a linear size greater than that expected from models of photodissociation by interstellar ultraviolet radiation. Comparing these sizes to the CO emission region sizes indicates that the circumstellar envelopes are dissociation-bounded. Spectra of the HCN (J=1-0) line are presented for both carbon stars. AFGL 2233 shows an unusual peak on the red side of the HCN line profile. This peak is unexplained and deserves further study. Using the observed spectra, we observationally test whether the observed velocity shift between CO and HCN emission lines in carbon stars is due to hyperfine interaction of the HCN.