Introduction of chemicals in the gaseous phase has the advantage of relative homogeneity and high transport rate. However, gas phase reactions lose the advantage of a high transport rate if large quantities of material are required in the desired reaction. Gas phase impregnations of wood will therefore be limited to applications requiring only a small quantity of chemicals evenly distributed through the wood substance. Gas phase application does seem to make possible wood drying with the development of fewer mechanical stresses, modification of wood with polymerized monomers, and the formation of wood derivatives in situ to alter physical properties. One of the most promising possibilities is the formation of compounds of high bacteriacidal and fungicidal activity at concentrations of a few parts per million; many are colorless. The possible use of methyl borate for fire proofing is also mentioned.