In 1825 a method of separating the sap from the tree without injury to the woody fibre was patented by Mr. Langton. He placed the wood in vertical cylinders of iron, from which he exhausted the air by condensing steam within them; after they were closed heat was then applied by means of a water-bath surrounding the cylinders. The sap in the form of vapour was conveyed by pipes to vessels immersed in cold water, where it condensed and was collected in a liquid state for removal.

The wood seasoned in this manner rather exceeds the usual density of similar timber when dried to the same extent, and it loses about the same weight as in seasoning by the ordinary process, but shrinks somewhat more.

The process is said to be complete on the liquid ceasing to collect in the condensing part of the apparatus.

The time required to extract the whole of the sap is from eight to twelve weeks, †