U. S. Department of Agriculture, Forest Servic e
FOREST PRODUCTS LABORATOR Y
In cooperator' .wish- tine University of ,Wisconsin
u -:.
CHEMISTRY OF WOOD
IX - Springwood and Summ•etwo©d
By GEORGE J . RITTER '
Chemist
and
L . C . FLECK
Associate Chemist
Pushed i n
JOURNAL OF INH'USTRIAL CHBMMITR Y
June, 1926
'
By
G . J . Ritter and L . C . Fi-&l
The purpose of the work reported in this paper .S to compare
the chemical composition of springwood and summerwood-in tbe- annual
' rings of trees .
tiu.
Snringwood differs from summerwood in phy0:cal appearance, :.
type of cell structure, density, and thickness of cell wall . It was
thought that analysis of the springwood and summerwood of representa tive species might show characteristic differences in the chemica l
composition of the two bands of growth and thus afford an additiona l
means of classifying woods . The principal differences discovered wor e
general, however, rather than individual,
Preparation of Samples for Analysis
=
In separating springwood from summerwood, i. is : or practicable to cut the bands from thin (3-mm .) crest sections of tele having
wide annual rings of growth . The width of the rings varies not only i n
different trees but also during different periods ira the history of th e
same tree . The latter condition makes it quite difficult to obtai n
suitable rings for springwood and summerwood samples representing a number of consecutive years in both the saptood and heartwood of a tree .
When suitable cross sections and areas of wood have been selected, th e
springwood and summerwood zones are aplit apart with a sharp wood chise l
and removed separately . This material is ground and sieved to 80-100 mesh size,
The methods of aia.alysis are the same as _descxa:bed in the sixth
raper of this series .a The results obtained for springwood and summer wood Of the six reprewgtative species chosen for study are recorded i n
the aemebmnanying table :' '
,t ressnt
2
. l?Pfpre the Cellulose Divi siori of the noriedn Clinical Societ y
I., April, 1924 .
mirtitnfiglighfiC
Indies ' f
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;t ,
: , ~•. _
,_
ti
Lignin and Cellulos e
The outstanding result of this work is the uniformly hig h
yield of lignin in springwood as compared with that in summerwood ,
showing that the wood substance laid down in the early growing seaso n
differs chemically from that grown in the late growing season . Th e
high proportion of lignin to total constituents in the springwood i s
accompanied by a low percentage of cellulose except in the heartwoo d
of loblolly pine and of red alder, in which the percentage of cellulose is also slightly higher in the springwood . Even here, however ,
the
ofgnit
]t
fa cellulose is higher in the springwood than i n
4ftfa
'e4oo d .
'w
4m. explanation of why the lignin c
st tut -s, a 1'aigpt,P pe r
cent of the total wood eubstr see in spr avgor o l',thal• . in summerwood i s
already available in •& recent paper3 by Ritter in which it was shown
that the lignin is'located partly in the cell wall mixed with the cello lase .and partly in the middle =lamella w-it 'v~esy little, if .
, othe r
s-uubstance present
. ose in *0k1gail w .11 ,
If the ratio of ligttn td• eel4
exclusive' of the• middle lamella, is the se--e
O3 ringsrood 40•
., nmerwood, then the lignin in the 'middle lamella, whi .6h eons'ti }
a greater
proportion of the total ti,ood substance in the spritOmo ., ofald account
Carr the higher proportion of lignin in springwwood t
ih. ftmnerwood .
i
o
-In,
L
The remainiig determinations *caved no uniform difference s
in eHemical composition betweef springwood and sumrmrwood, although a
tendency was apparent toward higher. percentages of (A,'pe `o sans i n
t
ap ringwood ; (b) pentosans 'in the isolated springwood cellulose ;
t.3 extractives in the springwood .
Conclusion s
' . (1) The data of this paper in Ji ate that : (1) A.higher percentate 'o'lignin exists in springwood''that in swnmerwood . An explanation Ts offered for the different lignin yiell .s in the two bands o f
growth .
.. • .
(2) Cellulose' 'orr~
la,-vter percentage of ,Rtle ttal woo,
substance in slnnmerwood t1a'ah in spr- xgwood .
triad & Ezeeri
(1925) .
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