THE NAVAL STORES INDUSTRY. 



25 



Table 14. — Summary of total yields for four years based on the dip and scrape being 

 corrected to the same number of chipping s per crop (8 ,000 faces) . 



Crop. 



Dip. 



Scrape. 



Yield. 



Increase. 



Yield. 



Increase. 



Decrease. 



A 



Pounds. 

 206,235 

 211,911 

 214, 503 

 279,260 



Per cent. 



Pounds. 

 47, 742 

 44, 838 

 39, 775 

 53, 915 



Per cent. 



Per cent. 



B. 



2.75 



4.01 



35.41 





6.08 



c 





16.69 



D 



12.93 









Two crops, G and H, were worked for one year, combining the 

 principles observed under crops B and C, namely, shallow and 

 narrow chipping. Crop X was chipped in the ordinary way. Table 

 15 gives the yields. 



Table 15. — Summary of yields for one year. Crops X, G, and H. 



Crop. 



Number 

 of 



cups. 



Number 

 of chip- 

 pings. 



Yield 



of 



dip. 



Increase. 



X 



9,880 

 9,880 

 9,880 



35 

 35 

 35 



Pounds. 

 90, 094 

 124,292 

 121, 474 



Per cent. 



G 



38 



H 



35 







As seen from Table 15 there is a decided increase in yield by the 

 use of shallow and narrow chipping. 



EFFECT OF TURPENTINE OPERATIONS ON TKMBER. 



INJURY FROM FIRE. 



Since the box is rarely more than 12 inches from the ground, it 

 is within easy reach of ground fires. As both box and face are 

 saturated with resin, a fire once started in the box may burn the 

 tree off at the base or render the face and box unfit to produce gum. 

 In cupped timber the cups are moved up at the end of the season 

 and are less exposed to fires. 



Another source of fire arises from the resin which impregnates 

 the ground at the base of the tree. Such resin may come from 

 losses in dipping, overflow from boxes on very productive trees, or 

 from leaning trees. This waste resin may defeat the entire purpose 

 of raking. Spilling is less likely to occur with cups than with boxes, 

 since the former can be detached and held directly over the bucket 

 in dipping. By having extra cups for very productive trees the 

 chipper who visits them weekly can quickly change the full cups 

 for empty ones and thus prevent overflow. 

 88767°— Bull. 229—15 4 



