| 摘要 |
Impregnation of wood with a liquid in a pressure vessel is assisted by evolution of gas or vapour from the liquid during the impregnation at a pressure below that applied to the wood. The gas or vapour may be methylene chloride (from tar oil) or carbon dioxide (from aqueous sodium fluoride), may be introduced into the wood before or with the impregnating liquid, and may be evolved by heating. Carbon dioxide may alternatively be formed in situ by first introducing formic acid vapour and then a solution of alkali metal carbonate or bicarbonate containing sodium fluoride; or by introducing acid and salt solutions, one of which contains sodium fluoride, in either order. The gas or vapour is removed by application of a vacuum.ALSO:Impregnation of wood with a liquid in a pressure vessel is assisted by evolution of gas or vapour from the liquid during the impregnation at a pressure below that applied to the wood. The liquid may be tar oil or a solution of sodium fluoride or a mixture of sodium fluoride, sodium bichromate, and disodium arsenate. The gas or vapour may be methylene chloride (from tar oil) or carbon dioxide (from sodium fluoride solution), may be introduced into the wood before or with the impregnating liquid, and may be evolved by heating. Carbon dioxide may alternatively be formed in situ by first introducing formic acid vapour and then a solution of alkali metal carbonate or bicarbonate containing sodium fluoride; or by introducing acid and salt solutions, one of which contains sodium fluoride, in either order. The gas or vapour is removed by application of a vacuum. |
