Evolution of gas-phase abundance of CH₃OH and ice-phase abundance of CH₂OH, CH₃O, H, and HS as predicted by the model of Barnard 1b using the binding energies of Model 1 of Table 8 and an initial sulfur abundance of S/H = 7.0 × 10^-6 (left) and S/H = 7.0 × 10^-8 (right). A significant amount of atomic hydrogen is sequestered when sulfur is highly abundant (left) to form icy HS, leading to a clear reduction of CH₂OH and CH₃O radicals in the ice matrix, which are involved in the production of methanol.