DISTILLATION OF STUMPWOOD. 



27 



of unavoidable transfer losses. The mean of the two, therefore, 

 is used in calculating gallons a cord. 



TABLE 13. Specimen log of a run of 150 pounds of Boise medium yellows-pine 



stumptvood. 



CHARACTER OF CHANGES OCCURRING DURING DISTILLATION. 



Wood tissue is made up primarily of cellulose, which, built up 

 into cells and tissue, constitutes the structural element of plants, 

 and lignin, which occurs as an incrusting matter or coating on the 

 cell walls. In resinous wood there is a further deposit in the wood 

 tissue of oleoresin from which the turpentine and pine oils are ob- 

 tained when the wood is subjected to distillation at a relatively low 

 temperature. 



As previously explained, the nonvolatile substance remaining 

 when the volatile oils are distilled from the oleoresin is rosin, a sub- 

 stance largely composed of abietic acid. Toward the end of the tur- 

 pentine stage of the distillation the contents of the retort may be 

 considered as made up principally of abietic acid, cellulose, and 

 ligninlike substances, all of which are composed of the elements 

 carbon, oxygen, and hydrogen. The molecules of these substances, 

 being comparatively large and complex, are readily broken down 

 by the application of heat into a series of simpler compounds, some 

 of which, reacting the one on the other, may form still other com- 



