66 BULLETIN ,1003, U. S. DEPARTMENT OF AGRICULTURE. 



beneficial. The solvent power of this turpentine appears to be 

 equal to that of turpentine from ordinary sources, and it is quite 

 as light in color. Its odor, while different from that of gum 

 spirits, is in no way objectionable, the main point of distinction in 

 this respect being the pine wood odor so characteristic of the better 

 quality of wood turpentine generally. 



While not suitable perhaps for all the technical uses to which 

 ordinary turpentine is adapted, this turpentine will answer for most 

 such purposes and it should find a ready market if properly intro- 

 duced to the trade. 



APPLICATION OF METHOD TO THE COMMERCIAL PLANT. 



The method of refining crude turpentine just described is readily 

 adaptable to the commercial plant. Two procedures may be fol- 

 lowed, according to the size of the plant and the available capital 

 for investment. The simplest and cheapest equipment for refining 

 the crude wood turpentine is a single copper refining still, so fitted 

 with a water-cooled return-flow condenser and a short fractionating 

 column and condenser, of any efficient type, that either one may 

 be used singly. After suspended and undissolved tarry matter has 

 had an opportunity to settle out, the crude turpentine is drawn into 

 the still, where it is mixed with the proper quantity of caustic soda 

 solution and boiled for the prescribed length of time, with the 

 return-flow condenser open and the fractionating column shut off 

 from the system. The heat for bringing the contents of the still to 

 a boil can be obtained either directly from a furnace under the still 

 or from closed steam coils inside the still at the bottom. The steam 

 coils are the safer arrangement. An open steam coil, with a number 

 of small openings along the length of the coil, is also placed inside 

 the still with the closed coil. This open coil may be connected by a 

 proper arrangement of piping and valves to both the boiler and a 

 small air compressor, and used during the preliminary boiling to 

 aerate the turpentine and alkali mixture. 



At the end of the preliminary boiling period the fractionating 

 column is opened, the return-flow condenser closed, and steam turned 

 on in the open-coil system. The turpentine and pine oil are distilled 

 off with the steam and collected in three fractions, as already out- 

 lined (p. 58). Toward the end of the distillation additional heat 

 may be supplied by again turning high-pressure steam into the 

 closed coil, to help drive over the last portions of pine oil. At the 

 end of the distillation the alkali residuum is drawn off from the 

 still. The same still may be used for the subsequent refrartionation 

 of the various fractions from the first distillation. 



A more expensive arrangement, that probably is better adapted 

 to a larger plant, consists of two separate stills, the first of which, 



