66 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. 
beneficial. The solvent power of this turpentine appears to be 
equal to that of turpentine from ordinary sources, and it is quite 
as light in color. Its odor, while different from that of gum — 
_ spirits, is in no way objectionable, the main point of distinction in 
this respect being the pine wood odor so characteristic of the better 
quality of wood turpentine generally. 
While not suitable perhaps for all the technical uses to which 
ordinary turpentine is adapted, this turpentine will answer for most 
such purposes and it should find a ready market if properly intro- 
duced to the trade. 
APPLICATION OF METHOD TO THE COMMERCIAL PLANT. 
The method of refining crude turpentine just described is readily 
adaptable to the commercial plant. Two procedures may be fol- 
lowed, according to the size of the plant and the available capital 
for investment. The simplest and cheapest equipment for refining 
the crude wood turpentine is a single copper refining still, so fitted 
with a water-cooled return-flow condenser and a short fractionating 
column and condenser, of any efficient type, that either one may 
be used singly. After suspended and undissolved tarry matter has 
had an opportunity to settle out, the crude turpentine is drawn into 
the still, where it is mixed with the proper quantity of caustic soda 
solution and boiled for the prescribed length of time, with the 
return-flow condenser open and the fractionating column shut off 
_ from the system. The heat for bringing the contents of the still to 
a boil can be obtained either directly from a furnace under the still 
or from closed steam coils inside the still at the bottom. The steam 
coils are the safer arrangement. An open steam coil, with a number 
of small openings along the length of the coil, is also placed inside 
the still with the closed coil. This open coil may be connected by a 
proper arrangement of piping and valves to both the boiler and a 
small air compressor, and used during the preliminary boiling to 
aerate the turpentine and alkali mixture. 
At the end of the preliminary boiling period the fractionating 
column is opened, the return-flow condenser closed, and steam turned 
on in the open-coil system. The turpentine and pine oil are distilled 
_off with the steam and collected in three fractions, as already out- 
lined (p. 58). Toward the end of the distillation additional heat 
may be supplied by again turning high-pressure steam into the 
closed coil, to help drive over the last portions of pine oil. At the 
end of the distillation the alkali residuum is drawn off from the 
still. The same still may be used for the subsequent refractionation 
of the various fractions from the first distillation. 
A more expensive arrangement, that probably is better edgpicd 
to a larger plant, consists of two separate stills, the first of which, 
