Contribution from the Forest Service 
HENRY S. GRAVES, Forester 
Washington, D.C. PROFESSIONAL PAPER October 2, 1917 
IN CREASED YIELD OF TURPENTINE AND. ROSIN FROM 
DOUBLE CHIPPING. 
By A. W. Scuorcer, Chemist in Forest Products, and R. L. PeTTicREew, 
Assistant Engineer in Forest Products. 
CONTENTS. 
: Page Page 
More naval stores from the same tree.....-.. 1 | Practicability of double chipping............ | 
Plan of the experiments................---.. 2 | Returns from double chipping, in dollars 
WNATCI SEC ey ee ene PNR Rs Ie 8 A 4 DMCC MESH OE GS hel BES RR! 2 & 
Effect of double chipping on the trees....... GSU ary iso BA CM RL Te ag oD 
MORE NAVAL STORES FROM THE SAME TREE. 
Naval-stores operators have the chance to get 31 per cent more 
turpentine and 36 per cent more rosin from their trees by increasing 
the number of chippings during a season. This has been determined 
by actual experiments made by the Forest Service on a tract in 
_ Mississippi, the results of which are presented in this bulletin. 
y Briefly, the method that gives the increased yields is to chip twice a 
week instead of once. At the same time, the streaks are cut only 
one-fourth inch high instead of one-half inch, the present standard 
practice. The faces, therefore, are no higher at the end of the 
season than when they are chipped once a week. 
Double chipping, of course, entails extra expense, but this is much 
more than offset by increased returns. With all additional expenses 
taken into account, and in the light of present prices, double chip- 
ping ought to increase the net profits from a crop (10,000 faces) by 
about $450. This means an increase in net profits from a 50-crop 
operation of about $22,000. 
While the experiments reported in this bulletin actually show 
a large increase in yields and revenue as a result of double chipping, 
it must be borne in mind that they cover only the first year’s opera- 
99163°—Bull. 567—17 
