PINE-OIL AND PINE-DISTILLATE PRODUCT EMULSIONS. 5 



120 gallons a cord, and the yield of pure pine oil was given as 1 to 

 4 gallons a cord. Veitch and Donk (28) give, for a cord of 4,000 

 pounds, a yield of from 36 to 120 gallons of crude oils and from 

 2 to 5 gallons of pine oil. At present the lower value may be par- 

 tially due to the fact that the distillers must use poorer grades of 

 lightwood than was necessary heretofore. 



The following diagrammatic scheme shows the. products of the de- 

 structive distillation of lightwood. 



Lightwood. 

 Distilled destructively. 



Aqueous liquor 



used for alcohol 



and acetates or 



thrown away. 



Gas used 

 for fuel. 



Lighter oils. 



J ^ 



Steam 

 distilled. 



Heavy oils. 



I 

 Distilled. 



Tar. 



Charcoal 

 to market. 



\ 



Creosote. Light oil. 



Steam distilled over soda. 



\! 



Light oil. 



Tar oil. 



Tar. 



Wood naphtha. Turpentine. Pine oil. Aqueous solution of creosote. 



Neutralized. 

 Creosote. 



STEAM DISTILLATION. 



Steam distillation of wood for turpentine and pine oil came later 

 than the destructive distillation. Patents for this process were 

 issued as early as 1864, but, according to Teeple (23), its rapid de- 

 velopment did not begin until 1902, probably because of the fact 

 that the price of turpentine, the main product, did not reach paying 

 levels until that time. 



Many variations of the steam process, including the use of super- 

 heated and saturated steam, various pressures, various shapes of 

 retorts, and different methods of steam circulation were patented; 

 but finally practically the same method of operation was universally 

 adopted (23) . The wood is " hogged " (chipped) , sometimes shredded, 

 put in retorts, and subjected to a saturated-steam extraction. At the 

 outset little or no pressure is used on the steam. When the volatile 

 products decrease, the pressure is raised 10 or 15 pounds and sub- 

 sequently reduced, when the steam and volatile products come out 

 from the chips together. This increase and reduction of pressure is 

 repeated several times. A yield of from 10 to 17 gallons a cord is 

 obtained. 



