OLEORESIN" PRODUCTION. 27 
the marked reduction occurring during the three years of turpen- 
tining is very apparent, although some allowance must be made for 
the fact that the greatest reductions in ring width after turpentining 
generally occurred in the trees with very wide rings, hence at least 
a part of the reduction noted might be attributed to this character- 
istic. 25 In general, it may be said that wherever trustworthy evi- 
dence is obtained it points to the conclusion that conservative chip- 
ping which does not unduly reduce the vitality of the tree, leaving 
unturpentined trees that are too small, not overcupping, and leaving 
sufficient bark bars pay in point of yields obtained and in reducing 
the number of trees which are killed or which dry-face. 
EARLY FOREST SERVICE EXPERIMENTS. 
Evidence pointing to the advantages of conservative chipping is 
also to be found in the results from some experiments carried on 
from 1905 to 1908. 26 The standard chipping of a commercial tur- 
pentine company not far from Jacksonville, Fla., was in this case 
used as a basis for comparison. It was slightly heavier chipping 
(streaks 0.6 to 0.7 inch deep and 0.51 inch high) than the standard 
chipping practiced in 1916 and 1917 at Columbia, Miss. Both slash 
and long-leaf pine were found in the stands of timber used. It was 
noted that the slash pine produced little or no scrape. The purpose 
of the work was to determine the results to be obtained from (1) 
shallower chipping, a reduction of depth of cut from 0.6 or 0.7 inch 
to 0.4 or 0.3 inch, the shallowest cuts being used on the slash pine ; 
(2) narrower chipping, an intended reduction in height of one-half, 
which was, however, in practice a narrowing from 0.51 to 0.4 inch; 
and (3) light cupping, the cutting of fewer faces, and the elimina- 
tion of turpentining of very small trees with a view to a second tur- 
pentining at some future time. 
It was reported that considerable difficulty was found in obtain- 
ing exact and uniform chipping, because of the change of chippers 
from time to time on the different crops. Another possible source 
of some error in the results was the method of determining the 
relative yields from the different crops by weighing the dip and 
scrape instead of the turpentine and rosin distilled from it. This 
method was found to be misleading in the case of the results ob- 
tained at Columbia, Miss., where it was found that a high weight of 
crude gum might be partly due to water mixed with the gum during 
rainy periods, and that it did not always indicate a proportionally 
high yield of turpentine and rosin (Table 5). 
25 A publication is in preparation by tbe Forest Service on the detailed results and 
relative yields from the different types of experimental chipping practiced on this tract. 
26 For. Serv. Bui. 90, p. 16. 
