OLEORESIX PRODUCTION. 37 
DESIRABLE PRACTICES. 
Ideal chipping should be deepest at the shoulder and shallowest at 
the peak or most exposed portion of the face, at which point the least 
normal and most harmful conditions, with respect to the vitality of 
the trees, are most likely to develop. 
Keeping the gum clean means high grades of rosin; hence it is 
well to cover the cup with a paddle during chipping (PL IV, fig. 4), 
or to equip the "puller" with a chip catcher (PL IV, fig. 6), to 
keep fragments of bark out of the gum during chipping and to avoid 
filling the cups with trash which will increase the apparent volume 
of the dip. 
DIPPING. 
Frequent collecting of the gum or dipping insures higher yields 
of turpentine. 35 Some advocate scraping off the hardened gum, or 
scraping with the paddle at each dipping instead of allowing it to 
remain until the end of the season and removing it all at once as 
was done in figure 4. Plate I. It is maintained that the latter prac- 
tice exposes the surface to undue drying, and that harmful cracking 
and checking may take place. Furthermore, the longer the scrape 
remains on the tree the greater is the reduction in the amount of 
turpentine which it will yield. A real reduction of waste may be 
obtained by using tight dip barrels. On one operation gasoline 
barrels were employed. Ideal dip containing about one-third more 
turpentine than usual was obtained by using closed glass cups for 
holding the gum as it exuded from the tree, but these were found to 
be very difficult and expensive to operate. 
YIELDS. 
It would appear as if under proper operating conditions more gum 
should be obtained at least during the second and third years than 
during the first, for many more resin passages are present. This, 
however, is not ordinarily the case in the United States. 36 On the 
Columbia. Miss., experiment the narrow chipping nearly held its 
own the second year, but during the first year the total yield, without 
reference to the amount of chipping surface used, was lower than the 
yield from the standard. 37 It seems entirely possible that an optimum 
35 In India dipping is as frequent as chipping. The same worker does both and is paid 
on the basis of the gum produced. One worker chips (by the French method) about 1.000 
faces or channels in 6 days. 
38 Since this was written, information has been obtained from Mr. F. Canning, con- 
servator of forests, India, concerning turpentine operations by the French method (very 
conservative chipping) on Pinus longifolia in the Kumaon Hills in the United Provinces, 
to the effect that, as a rule, more gum is obtained the second, third, and fourth years than 
the first. The yield the fifth year is about the same as that obtained during the first. 
37 Data from the Florida National Forest experiments about to be published are also 
of interest in this connection. 
