822( .41
ib 64
U. S. Department of Agriculture, Forest Service
FOREST PRODUCTS LABORATORY
In cooperation with the University of Wisconsin
MADISON, WISCONSI N
THE CONIFER LEAF OIL INDUSTRY
By A . W . SCHORGER
Chemist in Forest Products
Published in
AMERICAN LUMBERMAN
April 29, 1916
THE CONIFER LEAF OIL INDUSTRYBy
A . W . Schorge r
Chemist in Forest Product s
The production of oils from the leaves or needle s
of various conifers is a small but fairly old industry i n
the United States . According to the best estimates obtainabl e
the value of the oils produced annually from this sourc e
amounts to approximately $50,000 . The leaves of only a fe w
species of conifers are regularly distilled for their oils ,
since it is only for these oils that a steady demand ha s
been created . The principal species employed are the blac k
spruce (Picea mariana, Hill .), white spruce (Picea canadensis ,
Mill .), eastern hemlock (Tsuga canadensis, Linn .), red junipe r
(Juniperus virginiana, Linn .), and arborvitae (Thuj a
occidentalis, Linn .) . The oils of white spruce, black spruce ,
and hemlock are very similar in composition . No attemp t
appears to be made to keep the leaves of the latter specie s
separate, and for practical purposes a distinction betwee n
them seems unnecessary . The annual consumption of spruc e
and hemlock oil is estimated at 40,000 to 50,000 pounds .
It is quoted at 45 to 60 cents a pound . The leaf oil of th e
red juniper is used largely in insecticides, the annual consumption being 15,000 to 20,000 pounds . The prices of th e
oils from the various native conifers are approximately th e
sane as that given above . The oil of Pinus picea imported
from Europe is sold at about $4 per pound but the annua l
demand is below 50 pounds .
Yields of Oil from Various Specie s
The oil is found in longitudinal ducts runnin g
through the needles . The number and size of the oil duct s
vary greatly with the different species, and on these factor s
the yield of oil is largely dependent . The number of oi l
ducts may vary from one to ten . Naturally the species containing numerous ducts of large size will give the larges t
-Published in American Lumberman, April 29, 1916 .
R272
-1-
yield of oil . This assumption has been verified in the various species examined . The longleaf pine needle contain s
five large oil ducts, the average yield of oil being 0 .42
per cent, while the lodgepole pine needle contains two oi l
ducts, the average yield of oil being only 0 .16 per cent .
In all cases the yields are given in per cent of the weigh t
of the green leaves .
The approximate yields and principal constituent s
of the various species are given in the table presented o n
the following page .
Properties, Composition and Use s
As a general rule, the oils have a pleasant odo r
resembling the fragrance of coniferous forests . Occasionall y
the freshly distilled oils have a disagreeable odor tha t
frequently improves with age .
The oils are composed mainly of terpenes, terpen e
alcohols and their esters, and sesquiterpenes .
(See table . )
Among the terpenes pinene and limonene are ordinarily present .
The attractive odor of the oils is due mainly to borneol an d
its acetic ester . In general, the more highly prized oil s
contain large amounts of borneol, both free and combined .
Spruce and hemlock oil contain 35 to 50 per cent of thes e
constituents . The popular Siberian needle oil, of whic h
5,000 to 10,000 pounds are imported, contains from 29 t o
39 per cent bornyl acetate . Among the sesquiterpenes cadinen e
occurs most commonly . Thujone .is a characteristic constituen t
of thuja oil from Thuja plicata and Thuja occidentalis .
It is difficult to obtain direct information on th e
purposes for which the various oils are employed . A larg e
amount of correspondence addressed to manufacturers purporte d
to use these oils in their products afforded very little information . Information on the uses to which the oils are put
was obtained mainly from dealers and distillers of the oil .
The spruce and hemlock oils are extensively employe d
as a perfume in greases and shoe blackenings . They are als o
used in considerable quantities in liniments and othe r
medicinal preparations .
R272
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Cedar oil from Juniperus virginiana is' employe d
mainly in insecticides . Thuja oil from Thuja occidentali s
is used in insecticides and liniments . Various native and
foreign oils are employed medicinally as inhalations fo r
lung diseases, and as additions to baths and ointments i n
rheumatic afflictions . Various perfumes contain certai n
amounts of needle oils whose value consists in having a
so-called "ozonizing" effect . The oil of Pinus montana
tamed with chloroform is used in quantity as an eibrocation .
Tnt'Europe, especially, the finer neet1B 611 --grit ised .
tensively as perfumes in soaps .
"t
The great ,
ill ed i*'
lli'4 ' r
-small farriers in Ne
ngland during
onths when .'
the farm work is slacat t l~e , ?'~a
In 1912 a c
w4v eng od in the di
')*ton of t
of red ,l t
cata) oij an~~I,~q
>' "' The branches,,
3A4 inch
r
deli* r '` n Seattle in bundle o f
nt, ct price of
50 to $5 .50 per tort,
or). t'
oil content . The material was packed i n
'tom
E and 0
tilled with steam at a pressure of 40 t o
90, pCAi , for 3 - . 5-• ours, the distillation being discontinued when the amount of oil coming over did not excel
10 cubic 'centimeters in 5 minutes .
1
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'The average yield of oil was about 1 per cerit '-th-o weight of the green material . Young trees containe d
largest a lount Qf oil, and the haves= were richest in . .': •
January, , f ebru_a fir, , and , ag.rch . , T .,
a market value of . .
4+0
its a pi)
arcely suffici. _it to cove r
, buf' t *
ths cost of p
tion .
ri'f the oil was
v.
+o '
ITtsu31B.c'
e' is
insel44de ca
-'Mothine . " VIM, art . i
day '
cont
about 35 pc*,
of cedar &I' -End
45 por
t . of
1 ~~ . . bent made .
ating the fine .
gstbund Che1ls of peac 4 pits .
. i: ,tempts:-'hac,n mad®•4 i''OrItious times to utilil e
pine fiz
• .fstiori .of fiber after the oil:been removed by distillation . The most ambitious attemp
in this direction were made by C . A . and O . C . Terrell ,
Grant's Pass, Oreg ., who obtained patents Nos . 675,206 a
_
758,874, Rovering methods and apparatus . The plant, des Zbec
by Erown, utilized leaves systematically picked from On g
2
-Scien
. Amer . 84, 344 (1901) .
8272
-4-
trees of the western yellow pine . The stills consisted o f
wooden tanks with steam connections, and had a daily capacit y
of 2,000 pounds from which 10 pounds of oil were obtained .
After suitable treatment the spent needles produced a long . ,
tough fiber that could be woven into fabrics or made int o
mattresses when mixed with hair .
Forest Service Investigation s
The large amount of lumber cut from coniferou s
woods renders available large quantities of needles and twig s
that at the present time are not only a sheer waste but ar e
frequently the cause of destructive forest fires . If a sufficient market could be created for the oils a great economi c
advance in management would be effected . At present, however ,
the demand and price for oils of this type do not warran t
their manufacture on a large scale .
The leaves of a number of the most important wester n
and southern conifers were distilled to determine the yiel d
and chemical composition of the oil . Samples of these oil s
were sent to various manufacturers for practical tests . The
most promising oils, judged from odor, were those of the long leaf pine and western yellow pine . Unfortunately in nearl y
all the oils and ester content was low and their odors di d
not surpass those of the already firmly established spruc e
and hemlock oils . There appears to be an increasing utilization of conifer leaf oils, and the creation of a demand fo r
new oils, as well as the extension of markets for the commo n
ones, may be anticipated . It is frequently difficult, however ,
to introduce a new oil on the market, even though it may hav e
decided merit .
Principles of Distillatio n
The oil is removed from the leaves by the familia r
method of steam distillation, usually at atmospheric pressure .
As the steam passes upward through the needles the oil volatilizes and the mixed vapors pass together into a coolin g
apparatus where condensation takes place y. The condensatio n
products soon separate into a layer of oil and water, owin g
to their immiscibility and difference in specific gravity .
'S' :rig' distillation under pressure is more rapi d
and produces_iwot& *41 than distillation at ordinary pressure .
Then, steam dt dt.inospheWIPkessure is employed a greate r
yield;
obtained if tine n-d*d..es are cut into small pieces .
In this .may the oil ducts are more exposed to the action o f
the steam and more materi-a 'l tan be placed in the still .
Experiments have shown that a still will hold 25 to 50 pe r
cent more material when it is finely cut .
is
The largest yields are obtained from young trees .
In New England c- Oar oil is distilled almost entirely from
small tr,e•es growing- in. aid pas'Gur-es and abandoned fields .
All trrees growing ifs the open contain more oil than thos e
in a normal forest stand . The season of the year also appears to have a considerable effect, the data availabl e
essentially agrAeti g irvVhat the most oil is obtained during the winter amd spring months . The leaves of the wester n
red cedar (Thu12:plica ) were richest in January, February ,
and March ; the leaves oif •incense cedar vvexe r _~ e ice,
February and November than during tie 'llervening summeft -,
4 months .
TheStill and :_Tts 0a01j.on
ThM. exp -rimentaJ, - ,s : • .ll used by the., Forest
~~ c e
,e
4 = Sri•
onstructL i n
n~
+bed
f the - till for holdin g
et 6 in
height by 2 feet 3 inche s
s made of 1 6 B
G . copper . The ends wer e
'1-3/4 inches wide ,
and
the
.
**
he
heating vesse l
1. 1
ty
fla
and
ded w h rings . The cove r
`1
fast :
, linden with malleable iro n
usl in the joints .
In
base of the cylinde r
removable fram e
The exterio r
ed
ss►er .
of
asbestos
in
{
-. .
nsation
of
th
e
yeti• .~r~
~_
rr,► -~
-{'
r was 3 fee t
constructed o f
/2-in h
stop fo r
,' -- - - - e d
t.
1
~ F
-
-~
1-1/2 feet internal diameter, placed in a galvanized iro n
tank 2 feet in diameter by 2-1/2 feet deep . The condense r
was connected to the still with an 8-foot copper pipe, i n
two sections 2 inches in diameter . A 2-gallon aspirato r
bottle, having a brass syphon, served as a receiver .
The material to be distilled was first passed throug h
a feed cutter, the needles and twigs being cut into lengths o f
1/2 to 1 inch . When the chopped material was well packed int o
the still the charge varied from 350 to 500 pounds, dependin g
upon the species . By filling the cylinder ahead of the risin g
column of steam, the needles are decidedly more compressible .
The distillation was continued at the rate of 2-1/2 gallon s
per hour . At the end of 7 to 8 hours the quantity of oil fel l
to 5 to 6 cubic centimeters per hour, and the distillatio n
was then considered complete . The oils are dried and filtere d
through cotton batting or fine muslin, and are then ready fo r
market . Sometimes they are subsequently rectified by dealers .
The small distillers usually employ apparatus constructed partly of wood . The leaves are placed in rectangula r
cr cylindrical wooden tanks while steam is introduced from a
separate generator . The simple apparatus used by a Ne w
England distiller of cedar leaf oil will serve as a type o f
the stills frequently employed . His description is th e
following :
c
A steam-tight box, 3 feet by 4 feet and 3-1/2 fee t
deep, with a boiler plate bottom is set on a rock furnace . Inside of this box is a grating 4 inches abov e
the bottom to hold the cedar up to the top of the grat ing ; a pipe from the top of the box 10 feet long carrie s
off the steam . This steam pipe runs nearly its entir e
length through a trough of water kept cold by runnin g
water . The condensed steam drops into a glass ja r
covered with cloth for a strainer .