UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 343 



Contribution from the Forest Service 

 HENRY S. GRAVES, Forester 



Washington, D. C. 



PROFESSIONAL PAPER 



April 26, 1916 



GROUND -WOOD PULP 



Part I— THE GRINDING OF COOKED AND UNCOOKED 



SPRUCE 

 Part H— SUBSTITUTES FOR SPRUCE IN THE MANUFAC- 

 TURE OF GROUND-WOOD PULP 



By 



J. H. THICKENS, Chemical Engineer in Forest Products, and 

 G. C. M cNAUGHTON, Engineer in Forest Products 



CONTENTS 



Page 

 1 



Object of the Bulletin 



Present Status of the Ground-wood In- 

 dustry 2 



Present Methods of Manufacture ... 6 

 Part I— 



Equipment Used in the Experiments . 7 

 Methods Employed in Experimental 



Tests 9 



Effect of Preliminary Treatment of 

 Spruce • . . . 11 



Page 

 Part I— Continued. 



The Effect of Variable Grinding Con- 

 ditions ... 17 



Part II— 



Experimental and Commercial Tests 



on Various Woods 34 



Appendix A 67 



Appendix B 151 



WASHINGTON 



GOVERNMENT PRINTING OFFICE 



1916 



