10 WOOD TURPENTINES. 



The next step in the investigation, the study of the relations be- 

 tween composition and technical value, has been begun, but it will 

 be some time before the results are complete. 



METHOD OF ANALYSIS. 



It was necessary to devise a method for the examination of the 

 crude turpentines and the volatile products obtained from them which 

 would fulfill the following requirements: 



(1) Show quantitatively the proportions of the main constituents 

 of the material examined, especially of those constituents which were 

 to be separated in the refining process. 



(2) Show every possible difference in composition between the 

 various refined turpentines. 



(3) Be fairly simple and rapid in operation. 



No method was available which fulfilled all these conditions. The 

 ordinary methods for the examination of turpentines apply only to 

 the refined product (usually to gum turpentines) and are intended 

 mainly for the detection of adulterations. The method described in 

 Forest Service Circular 152 * most nearly fulfills these conditions, 

 because instead of determining the properties of the turpentine as a 

 whole the turpentine is first fractionated by distillation with steam 

 and the properties of the fractions are determined. By this method 

 some idea of the proportion of the various constituents can be 

 obtained. 



After an analysis by this method, however, the composition of the 

 turpentine could be expressed only in terms of " constituents uniform 

 in composition " and " heavy residue " without the possibility of dis- 

 tinguishing between the different kinds of turpentine or of obtaining 

 indications of the actual chemical constituents present. It was found 

 also (see pp. --to ) that the separation of the main constituents 

 of the turpentine by this method of distillation was so incomplete 

 especially in cases where comparatively large amounts of "heavy 

 residue " were present that the quantitative expression of the com- 

 position of the turpentine, even in such general terms as " constituents 

 uniform in composition " and tc heavy residue," was not accurate. It 

 was necessary, therefore, to develop and adapt for use in this investi- 

 gation another method for the examination of turpentines. 



DESCRIPTION OF METHOD. 



This new method is similar in general principles to that described 

 in Circular 152, but it is modified in several details to make it simpler, 

 more accurate, and more rapid. 



1 " The Analysis of Turpentine by Fractional Distillation with Steam," by W. C. Geer.. 



