OLEOEESIN PEODUCTIOlsr. 19 



In the second year in all crops there was some decrease in total 

 yield. The 1917 comparisons, using the total 1916 yields from a 

 crop as 100 per cent or the criterion for judging the relative yield 

 of that crop, showed that the greatest decrease occurred in the stand- 

 ard tract.- (Table 5.) 



DOUBLE CHIPPING. 



The special feature of this method, used for two years on this 

 area at Columbia, Miss., was that the streak was cut at four-day 

 intervals instead of only once each seven days. This type of chip- 

 ping was used (PI. IV, figs. 3, 5, and 6) on about 3,000 faces on the 

 same kind of timber as that in the standard experiment. Only as 

 much wood as was cut in the standard chipping was removed by 

 this double method, since the dimensions of the streak specified were 

 one-half inch deep and one-fourth inch high, cut twice weekly. The 

 depth in general tended to average slightly less in the double than 

 in the standard. During 1916 the chipping was carried on with a 

 "00" hack (PI. IV, fig. 2) and a streak averaging 0.32 inch was ob- 

 tained (Table 6, footnote). In 1917 a "puller" (PI. IV, fig. 6) was 

 used, and a more accurate narrow chipping or rather " pulling " 

 was obtained (average 0.26 inch) as is indicated in Table 6. This 

 was also more accurate chipping than was obtained in 1917 on the 

 single narrow-chipped area (average height of streak 0.34 inch), 

 where a hack was used. It is of considerable interest to note that 

 with this narrow chipping the double showed a smaller relative re- 

 duction in the second-year yield of turpentine, when compared to 

 that of its first-year yield, than was shown by the wider-chipped 

 (one-half inch per streak) standard. This was true in spite of the 

 fact that the vitality of the double-chipped timber had apparently 

 suffered rather more severely from the process of turpentining than 

 had the standard. 



In figures 3 and 4 are given the monthly observations on the five 

 trees selected from the double area for 1916 and 1917, respectively 

 (different sets of five each 3'ear). The same reduction as in the case 

 of the standard was noted. in the number of resin passages per unit 

 area of the 1916 ring, as wns observe! in material cut at the level of 

 tin- 1917 chipping. The tendency for fewer resin passages to he 

 present at Hie cud of (lie 11)17 season than in midsummer was also 

 observed. In 1017 practically all five trees from Hie double area 

 snowed that their wood cbrmatiori had suffered as a consequence of 

 that method of turpentining, and (hat (hey had not been able to 

 recover, as many of (he narrow area trees had, or even been able to 

 hold their own during l!M7. \\\c second year of turpentining, as some 

 of the standard area trees appeared to have done. 



The re nits from the examinations of the 50 specimen collected 



a I the end of the -ca.-oii each year are gi veil in Tallies 2, •".. and I. In 



