DISTILLATION OF STUMPWOOD. 31 



CRUDE PRODUCTS OF RETORT DISTILLATION. 



CRUDE WOOD TURPENTINE. 



The crude wood turpentine is distilled from the wood during the 

 first stage of the destructive distillation. During this first stage of 

 distillation the turpentine passes over for the most part unchanged, 

 as it probably exists in the wood tissue. The crude first turpentine, 

 therefore, is nearly free from pyroligneous bodies. It is often light 

 in color, and usually possesses an agreeable odor. It has a specific 

 gravity of about 0.875 at 20 C., a refractive index of about 1.4768 

 at the same temperature, and an initial boiling point of about 164 C. 



The crude second turpentine necessarily contains more of the pyro- 

 ligneous or heat-decomposition products and of the heavier pine oils, 

 since the retort operator cuts the distillate at the first signs of de- 

 composition of the wood, indicated by the appearance of noncon- 

 densable gases, and collects the remainder of the turpentine as " sec- 

 onds." The heat-decomposition products of the rosin and wood 

 constituents consist of acids, alcohols, ketones, phenols, aldehydes, 

 etc., the nature and quantity of which depend on the temperature 

 and rate at which the turpentine stage of the distillation is conducted. 

 This crude second turpentine is darker than the crude first, and its 

 color is sharper and more suggestive of wood decomposition. It has 

 a specific gravity of about 0.910 at 20 C., a refractive index of about 

 1.4850 at the same temperature, and an initial boiling point of about 

 130 C. (due to the presence of decomposition products). 



The difference between these two crude turpentines is well set forth 

 in Table 15. 



TABLE 15. Products of dry distillation of crude turpentine at 760 mm. pressure. 



The details of refining the crude turpentine are discussed on 

 page 56. 



LIGHT OIL. 



The crude light oil is brownish black, has a sharp, penetrating, 

 empyreumatic odor, an average specific gravity of about 0.995, a 

 refractive index of 1.514, each at 20 C., and an acid value of about 

 29. Its average viscosity at 25 C. is 2.58 Engler. The yield is 

 about 4^ gallons a cord of rich wood. Distilled in the ordinary 

 manner at atmospheric pressure, using a fractionating column, it 

 has an uncertain initial boiling point, around 70 C., due to the pres- 



