8 DISTILLATION OF RESINOUS WOOD BY SATURATED STEAM. 



There seemed to be, therefore, a profitable field for investigations 

 to determine the relations between the conditions under which the 

 distillation is conducted, on the one hand, and, on the other, the 

 amount and kind of products, and the readiness with which they are 

 obtained. The results of the investigations are set forth to help 

 promote the expansion of the steam distillation industry, and to 

 increase in this way the utilization of a class of material which now is 

 wasted. 



THEORETICAL CONSIDERATIONS. 



In the description of the experimental work and the discussion of 

 the results it will be necessary to refer constantly to certain theo- 

 retical principles which apply to the distillation of volatile oils with 

 steam, and, in order to make the future discussion clearer, these 

 principles are briefly presented. 



In order to simplify the deductions, the following assumptions are 

 made in regard to the resinous material contained in the "light wood" 

 from the longleaf pine: * 



(1) It is composed only of turpentine, pine oil, 2 and rosin; 



(2) The components are all simple substances completely soluble 

 in one another; 



(3) None of the components is soluble in water; 



(4) The turpentine and pine oil are both volatile, but the turpentine 

 has the lower boiling point; 



(5) Kosin is nonvolatile. 



While these assumptions are not strictly true in all cases, none of 

 them is sufficiently incorrect to seriously affect the conclusions. 



The following deductions can be made as to distillation of the 

 resinous materials, defined by these assumptions, with steam: 3 



(1) There will be a separation of the two volatile constituents, 

 with turpentine in greater proportion in the first part of the distillate 

 and pine oil in the latter part. 



(2) Under normal pressure the temperature of the distillation will 

 be slightly above 95 C. at the beginning, and will rise throughout 



1 M. Vezes (Bull. Soc. Chem., 29, 470-478, 1903) has given a very clear and complete discussion of the prin- 

 ciples underlying the distillation of the oleoresin from the maritime pine of France. For the simplification 

 of the discussion. the following assumptions were made: 



(1) That the oleoresin is composed only of essence (turpentine) and colophony (rosin); 



(2) That these components are both simple substances completely soluble in each other; 



(3) That neither is soluble in water; and 



(4) That rosin is nonvolatile. 



In regard to the oleoresin obtained by chipping the live longleaf pine tree of the United States the same 

 assumption can be made, but the oleoresin contained in the pitchy "lightwood" from this species has 

 another component, the heavy, high-boiling "pine oil," which must be taken into consideration in the 

 discussion of the steam distillation of such wood. 



2 A discussion of the occurrence of pine oil in the "lightwood" of longleaf pine is given in Forest Service 

 Bulletin 105, "Wood Turpentines, Their Analysis, Refining, and Composition," by L. F. Hawley. 



3 A detailed discussion of the methods used in making these deductions can not be given here, since a 

 complete exposition of the laws governing the distillation of a four-component system like this would 

 require too much space. 



