6 



BULLETIN 567, U. S. DEPARTMENT OF AGRICULTURE. 



In Table 4 the total quantities of turpentine and rosin obtained by 

 narrow, double, and standard chipping are compared on a percentage 

 basis. Double chipping increased the yields of turpentine and rosin 

 30.9 per cent and 36 per cent, respectively. The greater increase in 

 rosin is due to the heavy yield of scrape. The yields of turpentine 

 and rosin were decreased 17.4 per cent and 17.5 per cent, respectively, 

 by narrow chipping. It will be noted, however, that the narrow 

 faces are only about one-half the height of the standard or double 

 faces. The comparative heights of the faces are shown in Plates I 

 and II. 



In Table 5 the yields have been arranged with respect to the 

 height of face, the widths of all the faces being practically identical. 

 On this basis the narrow chipping produced about 40 per cent more 

 turpentine and rosin than the standard. Narrow chipping, however, 

 would not be practical in the light of present prices for labor and 

 timber leases. 



Table 4. — Comparison of the yields per crop by the various methods of chipping. 



Plot. 



Yield of i Compared 

 turpen- | ■with 

 tine. I standard. 



Yield of 

 rosin. 



Compared 



with 

 standard. 



Standard chipping 

 Narrow chipping. . 

 Double chipping.. 



Gallons. 

 3,260 

 2,693 

 4, 267 



Per cent. 

 100 

 82.6 

 130.9 



Pounds. 

 105,539 

 87, 014 

 143,542 



Per cent. 

 100 

 82.5 

 136 



EFFECT OF DOUBLE CHIPPING ON THE TREES. 



The effect that double chipping will have upon the timber during 

 subsequent years of operation must be considered. The same trees 

 will be tapped during the coming season, and until the additional 

 data are available the advisability of using the method over a period 

 of years must remain in doubt. Some data in regard to the severity 

 of the several methods, however, will be found in Table 2. By far 

 the greater number of faces recorded in this table, especially those 

 that had lost from to \ the season, were "dry" faces. This con- 

 dition has been the result of old or "doty" timber or the direct 

 result of turpentining. In the standard chipping a total of 235 

 faces, or 38.3 per thousand, were affected. The narrow chipping 

 contained 223 injured faces, or 32.4 per thousand, while the double 

 chipping contained 165, or 54 per thousand. 



This would seem to indicate that double chipping is the severest 

 and narrow chipping the least so. However, in the second part of 

 Table 1, it will be noted that in the standard chipping there were 

 32 faces on trees that had died for no apparent reasons, equivalent 

 to 5.2 faces per thousand. For the narrow and double chipping the 



