The rates of a number of homogeneous gas phase reactions likely to occur in dense interstellar clouds composed primarily of molecular hydrogen are considered. Over 100 reactions are included; of these, more than half have known rate constants. These reactions are sufficient to produce and destroy polyatomic species such as H2O, HCN, NH3, and H2CO. Steady-state abundances of about 35 species are calculated for clouds of density 1 0 < < 106 cm -3. Calculations are performed for cosmic-ray-induc...
