Spectra for the clouds that have not been mapped, as in Fig. 1. The axes are the same for each cloud. ¹²CO is in black and corresponds to the temperature scale. ¹³CO is in red and has been multiplied by 5. HCO⁺, in green, has been multiplied by 35. The HCN spectra have been multiplied by 35 for comparison with HCO⁺ but also multiplied by 9/5 to account for the satellite lines as explained in the text. The ¹²CO and ¹³CO spectra have been convolved with a Gaussian kernel to the angular resolution of the HCN and HCO⁺ spectra.