  We have observed the hard X-ray source 1E1740.7-2942 in the HCO+ (1-0) line
using the Owens Valley millimeter interferometer. Previous single dish
observations have found HCO+ emission coincident with the location of the radio
continuum hot spots of the radio source associated with 1E1740.7-2942. Our
higher resolution observations show a 15 arcsec offset between the HCO+
emission and the location of the radio hot spots. We propose that the lack of
emission results from a large ionization rate, exceeding $10^{-15}$ s$^{-1}$,
in the neighborhood of 1E1740.7-2942.
