Scientific and other notes on essential oils. 63 



easily soluble, whereas if exposed to the air for only 26 hours, it looses so much in 

 solubility that 40 percent, less than in a fresh state are absorbed by the solvent. The 

 freshly hewn wood, immediately on leaving the saw, is introduced into a boiler, capable 

 of being closed and heated, and locked therein in a steam-tight manner. An evaporator, 

 fixed close to this dry boiler, now supplies an uninterrupted stream of an auxiliary 

 vapour, preferably with a constant boiling point, and from an organic liquid not 

 miscible with water, and in the case of coniferous wood being a good solvent for 

 resin and oil; at the same time the dry boiler is heated continually in order to prevent 

 the condensation of the auxiliary vapour in the pores of the wood and a too extensive 

 extraction of the latter which would affect its strength and resistance. As soon as 

 the vapour has begun to act only a short time, the sap of the wood begins to flow 

 and indeed it streams from the lower discharge pipe of the boiler in a liquid state as 

 well as in the form of a mixture of steam and of auxiliary vapour rising from a 

 channel at the top of the dry boiler and then into a condenser where the mixture is 

 condensed. The liquids then are generally run into an automatic separating vessel, 

 in which the water, charged with the exuded and volatile components of, the sap, 

 separates, when at rest, completely from the water-repelling auxiliary liquid, according 

 to the specific gravity, so that the water flows in an uninterrupted stream from the 

 one discharge pipe of the separating vessel into a reservoir, whereas, on the other 

 hand, the condensed auxiliary liquid, charged with resin, oil of turpentine, fat, 6jc, 

 runs out of the 2 nd discharge pipe of the separating vessel and then back again to 

 the evaporator. At the end of the drying process the resin, §c, which has been 

 detached from and dissolved out of the wood remains in the evaporatoy as an " extract' ' 

 after the auxiliary vapour has been distilled off. This "extract" is then run off and 

 preferably transferred to plant erected in common for working up such residues. 

 Investigations as to the value of the sap-water have still to be made. Theoretically, 

 a small quantity of solvent would suffice to render an unlimited quantity of wood ripe 

 for manufacture, but in practice one must reckon with a loss of solvent of 1 per cent, 

 of the rough wood weight. The distilling process is continued until no more water 

 runs from the separating vessel, which in some cases dribbles slightly. Besides this 

 criterion for the termination of the drying process, there is another one, namely that 

 the temperature in the drying boiler only reaches the boiling point of the auxiliary 

 liquid when all the moisture has been driven out of the wood. As long as the latter 

 still contains much moisture, the temperature of the vapour mixture remains fairly 

 constant at a certain level below the boiling point of the lowest-boiling component 

 of the vapour mixture, as for instance at 75°, when the vapour mixture consists of 

 the vapour of trichlorethylene, boiling point 88 to 90°, mixed with steam. It then rises 

 quite gradually, as the water gives out, and only mounts up to 88° when the last drops 

 of water have escaped. Wood, dried in this manner, is also perfectly sterile, nor does 

 it contain any living insects or their larvse or eggs. 



On an average there might be obtained about 1 per cent, of rosin, oil of turpentine, 

 fat, §c, accordingly from 12462000 tons of resiniferous wood, produced in Germany, 

 about 124620 tons of extract which would about cover the German demand for rosin 

 and oil of turpentine. If the value of extract is taken at o4l 1. — per kilogramme. 

 Germany could obtain, solely by adopting this rational quick-ripening process for wood, 

 a value amounting to cM 124620000 from the extract. Besides which, no consideration 

 has been paid to the value possibly obtainable from utilizing the sap-water. 



Germany, however, has other sources of resin at her disposal besides the method 

 just described, as Russia, Austria, and Hungary together supply her with 4622570 tons 



