Scientific and other notes on essential oils. , 77 



produces a yield of 700 to 1000 kg. of pine oil, 1000 kg. of wood tar, and 4800 kg. 

 of charcoal, suitable for forging purposes. 



H. Harkort 1 ) has also described the production of oil of turpentine, or rather of pine 

 oil, tar, and charcoal in Poland. He publishes his remarks as a sort of continuation 

 of Schelenz's 2 ) paper on the same subject which we have also discussed; however, 

 we did not give a description of the distillation plant because, as Harkort also remarks, 

 it appears to have been defective and incomplete, probably owing to the fact that 

 Schelenz had to depend for his information on facts adduced by other people. Harkort 

 was in a position to rectify Schelenz's data, as he was able to study such a plant in 

 action himself and obtained reliable information as to the construction and dissemination 

 of the individual types of heating apparatus. 



As a matter of fact, it is a question in such works to produce "oil of turpentine", 

 (pine oil), tar, and charcoal from the root-stocks of Scotch pines. These root-stocks 

 ought to remain in the ground as long as possible after the trees have been felled, 

 even for 10 or 15 years, as the yield of pine oil is said to depend mainly on this 

 circumstance. Only in the case of the Bialovitsh forest the root-stocks are said to 

 be so full of oil that they can be utilized even after only 2 years. The outside layers 

 of the root-stocks are, of course, quite rotten then and must be removed by being 

 hacked off. The dry distillation process is conducted according to 2 different methods, 

 either in "Polish" or in "Russian" heating plants. 



The Polish furnace is the older system. It is a case of a round furnace whose 

 utmost dimensions do not exceed 4.20 m. in diameter and 4.20 m. in height, with a 

 lower, almost perpendicularly rising part, and a dome. The former is built up of a 

 wall of a thickness of 3 bricks and rises to half the height of the total elevation, 

 whereas the dome is only one stone thick. At both sides of the working-door which 

 is placed quite low down, the fire-places are fixed whose fire-gases pass through 

 horizontal channels, are conducted on the opposite part of the furnace side by means 

 of the perpendicularly rising conduits to a higher level, and lead back by means of a 

 second perpendicular conduit on both sides, ultimately reaching the chimney which is 

 about above the working-door. The floor of the furnace is provided in the middle 

 with a gradient, thereby permitting the collecting tar to find an exit outside through 

 a channel. After charging the plant with root-stocks the furnace is lighted, wood being 

 used. Pine oil, mixed with water-vapour, then passes over for 3 or 4 days, and in 

 point of fact through a lateral opening in the dome or better still through one at the 

 apex, to which a condensation tube is affixed. After this period the tar begins to run 

 along the floor of the furnace, the upper distillation opening being then closed. The 

 heating process is continued till no more tar runs off. By that time the contents of 

 the furnace have been converted into charcoal. 



This process is a kind of dry distillation, whereby the production of "oil of turpen- 

 tine" in the real sense of the word, i. e. of a product resulting from gum turpentine 

 by distillation with steam, is quite excluded, on the contrary merely a kind of pine 

 oil is produced. Even the oil which first distils from a "Polish furnace" is quite impure 

 and the yield suffers from the circumstance that a too early rise of temperature de- 

 composes the turpentine still present. During the period of pine oil production the 

 temperature ought not to rise above 100°, in spite of this fact, however, after 3 or 

 4 days this increase takes place, so that the condensation-products are so dark in 



l ) Zeitschr. f. anyev:. Chem. 29 (1916), I. 361. — 2 ) Ibidem 251; Report October 1916, 55. 



