The decomposition of wood by heating at high temperature in the absence of air produces products like gases carbondioxide, carbon monoxide, methane, liquids, and a solid residue -charcoal. The gases and liquids are separated as volatile products and on cooling a distillate is obtained. The distillate, in turn, separates into pyro-ligneous acid and woodtar. The acid can be treated to give acetic acid, methanol, and other products.