EXPERIMENTS IN REFINING WOOD TURPENTINE. 27 



Two forms of the continuous still are shown in figures 3 and 4. 

 These may be operated together to obtain three products, or indi- 

 vidually to obtain two products. The crude turpentine enters the 

 column through pipe 2 in a continuous stream. Here it comes in con- 

 tact with live steam entering below and is carried upward where it is 

 fractionated; the light oils of any desired composition, depending on 

 the volume, speed, and temperature of the entering steam, pass con- 

 tinuously from the head of the column, are condensed, and run into 

 storage tanks, while the heavier oils pass downward and out at the 

 bottom of the still into a second and usually smaller column, or into 

 a pot still from which they are again distilled. This distillate is pine 

 oil of one or more grades and is heavier than that obtained from the 

 first column. The condensed water and small quantities of other 

 materials appear as waste at the bottom of the shorter column or 

 remain in the pot still. The distiUate from the first column should, 

 under proper conditions of operation, contain all the wood turpentine 

 and but little of the heavier constituents, such as the pine oils, etc., of 

 the crude oils. These pine oils, if present, can be separated by a sec- 

 ond distillation of the portion containing them. The composition of 

 the first distillate may be largely controlled by the manipulation of the 

 still, especially by the speed and the ratio between the steam and 

 the crude oils entering the still. The pot still may be readily con- 

 verted into a column periodic still by replacing the gooseneck with a 

 suitable column. 



It is highly important in turpentine distillation that the condens- 

 ing surface be ample to fully condense the vapors and cool the con- 

 densed liquids to about 70 F. An insufficient condensing surface is 

 too often a fault of wood distillation plants. It is to be borne in 

 mind that in the South the water available for condensing and cool- 

 ing has a higher temperature than that used farther north, and 

 consequently larger condensers and more water are required. The 

 consumption of cooling water may be greatly reduced by the use of 

 large atmospheric condensers. 



EXPERIMENTS IN REFINING WOOD TURPENTINE. 



The purpose of refining crude wood oils is to separate them 

 into their constituents or into fairly definite mixtures of commer- 

 cial value. That portion known as "wood turpentine" should 

 be similar to freshly distilled gum spirits as a paint and varnish 

 thinner and be as free as possible from the very objectionable odor 

 of the crude or imperfectly separated wood turpentine. Properly 

 made wood turpentine should dissolve gums and resins as well as 

 gum spirits, and when used in paints and varnishes they should be as 

 durable and dry rapidly without pinholes and without crawling. 



