6 CONTENTS. 



Results of examinations by species Continued. 



Pinus edulis Engelm 28 



Examination of the oleoresin 28 



Examination of the volatile oil 28 



Physical properties 28 



Identification of the constituents 28 



Examination of the rosin 29 



Conclusions 30 



Summary 30 



Comparisons with commercial naval stores 30 



Volatile oil 30 



Rosin.. 36 



ILLUSTRATIONS. 



PLATES. 



Page. 



PLATE I. Fig. 1. Resin crystals from Pinus sabiniana; formed by rapidly 

 crystallizing, from alcohol and hydrochloric acid. Fig. 2. Resin crystals 

 from Pinus sabiniana; formed by crystallizing, from acetone 20 



TEXT FIGURES. 



FIG. 1. Boiling-point curves for the volatile oil 31 



2. Specific-gravity curves for the volatile oil 32 



3. Index of refraction curves for the volatile oil 33 



4. Fractional distillation, specific gravity, and index of refraction curves 



for the volatile oil. . 34 



