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chemistry cr wood

IX. Springujccd and Summeriuccd

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UNIV OF FL LIB
DOCUMENTS DEP^

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UNITED STATES DEPARTMENT OF AGRICULTURE

FOREST SERVICE

FOREST PRODUCTS LABORATORY

IvI a d i s o n, Wisconsin

In Cooperation with the University of Wisconsin
July 1930

Digitized by the Internet Archive

in 2013

http://archive.org/details/chepOOfore

CHEMISTRY OF ¥001
Part IX — Springwood and SummerwoodJi

By

G. J. RITTER, Chemist
and
L. C. FLECK, Associate Chemist

The purpose of the v;ork reported in this paper is to compare
the chemical composition of springwood and summerwood in the annual
rings of trees.

Springwood differs from summerwood in physical appearance,
type of cell structure, density, and thickness of cell trail. It was
thought that analysis of the springv/ood and summeruood of representa-
tive species might show characteristic differences in the chemical
composition of the two "bands of growth and thus afford an additional
means of classifying woods. The principal differences discovered were
general, however, rather than individual.

Preparation of Samples for Analysis

In separating springwood from summerwood, it is most practic-
able to cut the "bands from thin (3-mm. ) cross sections of wood having
wide annual rings of growth. The width of the rings varies not only in
different trees, but also during different periods in the history of the
same tree. The latter condition makes it quite difficult to obtain
suitable rings for springwood and summerwood samples representing a
number of consecutive years in both the sapwood and heartwood of a
tree. When suitable cross sections and areas of wood have been
selected, the springv/ood and summerwood zones are split apart with
a sharp wood chisel and removed separately. This material is ground
and sieved to 80-100-mesh size.

The methods of analysis are the same as described in the sixth
paper of this series.— The results obtained for springwood and summer-
wood of the 6 representative species chosen for study are recorded in
the accompanying table.

1
Presented before the Cellulose Division of the American Chemical

Society, Washington, L. 0. , April 1924. Fublished in Industrial

&. Engineering Chemistry, 18: 608-9 (1926).
2
-Industrial & Engineering Chemistry, l4:1050 (1922).

R950

Lignin and Cellulose

The outstanding result of this work is the uniformly high
yield of lignin in springwood as compared with that in summerwood,
showing that the wood substance laid down in the early growing season
differs chemically from that grown in the late growing season. The
high proportion of lignin to total constituents in the springwood is
accompanied by a low percentage of cellulose except in the heartwood
of loblolly pine and of red alder, in which the percentage of cellu-
lose is also slightly higher in the springwood. Even here, however,
the ratio of lignin to cellulose is higher in the springwood than in
the summerwood.

An explanation of why the lignin constitutes a larger per-
cent of the total wood substance in springwood than in summerwood is
already available in a recent paperl by Hitter in which it was shown
that the lignin is located partly in the cell wall mixed with the cel-
lulose and partly in the middle lamella v/ith very little, if any, other
substance present. If the ratio of lignin to cellulose in the cell
wall, exclusive of the middle lamella, is the same in springwood as
in summerwcod, then the lignin in the middle lamella, which constitutes
a greater proportion of the total wood substance in the springwood,
would account for the higher proportion of lignin in springwood than
in summerwood.

The remaining determinations showed no uniform differences
in chemical composition between springwood and summerp/ood, although a
tendency was apparent toward higher percentages of (a) pentosans in
the springwood; (b) pentosans in the isolated springwood cellulose;
(c) extractives in the springwood.

Conclusions

Th<=. data of this paper indicate that: (l) A higher
percentage of lignin exists in springwood than in summerwood. An
explanation is offered for the different lignin yields in the tv/o
bands of growth.

(2) Cellulose forms a larger percentage of the total wood
substance in summerwood than in springwood.

industi

:rial & Engineering Chemistry, 17:119^ (1925),
R950 -2-

Table 1. --Analyses of springwood and summerwood of some American woods.
(Results in percentages on oven-dry (105° C. ) samples. )

Species

Eouglas fir
Heartwood
Springwood
Summerwood

Western

white pine
Heartwood
Springwood
Summerwood

Loblolly pine
Sapwood
Springv/ood
Summerwood
Heartwood
Springv/ood
Summerwood

Red alder
Heartwood
Springwood
Summerwood

Catalpa

Sapwood
Springwood
Summerwood

Heartwood
Springwood
Summerwood

White ash,

sp. gr.0.68
Sapwood
Springwood
Summerwood

: Sample

:Mois- :

: ture :

: 31S
: 319

6.92:
4.S2:

; 316 ;

: 317 :

4.78:
3.^7:

: 302 :
: 303 :

2.82:
3.39 =

: 304 :
: 305 :

3.13:
2.16:

: 300 :
: 301 .

3.25:
3.16:

: 312 :
: 313 :

6.76':
4.04:

; 3iu ;

: 315

6.17:
4.76:

: 302
: 309

3.93 =
2.89:

Solubility in

:Ace-

:Meth-

:Fento-

:Lignin

•Cellu-:

• tic

:oxyl

sans

• lo se :

Cold: Hot: 1$

:acid

water :NaOH

:

3.00:4,67:15.10
2.15:3.76:14.56

•0.62
.71

3.48
3.40

11.97
9.89

32.61
29.20

55.95:
59.35:

3.76:5.16:22.08
4.29:5.^2:21.47

1.42

i.4o

3.68
3.25

10.07
9.82

26.30
25.30

57- 60:
60. 00:

3.28:3.49:11.11
2.18:2.97:11.01:

1.28
1.4l-

4.05:
4. 18 :

11.59
11.12:

28.12
26.78:

58.06:
6l. 21:

7.50:7.16:15.14
7.64:6.44:21.19:

1.00-
1.11.

6.17:
6.88:

12.77:
12.12:

26.78.
24.18:

53.44:
52.87:

3.02:4.01:20.49:
3.03:4.16:21.15'

3.69:
3.60

5.18
5.55:

22.37.
23.36-

24.70
23.O3:

58.38:

57.16:

9.12-12.44:34.45
7.29-10.11:27.97

3.33
4.45

4.44
4.10

22.39:
22.35

23.64i
18.68-

50.37:
56 . 49 :

7.510.1.65:34.27
2.69:5.26:24.15

3.39
4.07

^.97
3.37

21.33
21.50

24.29
19.35

50.38:
58.45:

8.84-10.99:23.71

6.13:8.18:19.32

53.11

:2.76

1 5.^9
: 5.1*

21.45
: 20.51

• 24.35
: 23.68

i+9.73:
54.17:

Pentosans
in
cellu-
lose

R950

-3-

( continued on next page)

Table 1. — Analyses of springwood and summerwood of some American woods (continued'
(Besults in percentages on oven-dry (105° C.) samples.)

Species

: Sample

:Mois-

: Solubilil

;y in

:Ace-

:Meth-

:Fento-

•Lignin

:Cellu-

:Fentosans

• t i r

: oxyl

:Cold: Hot: 1$

:acid

cellu-

: water

' NaOH

lose

"..Tiite ash,

sp. gr.O. 71
Sapwood
Springwood:
Sumraerwood

3O6
307

U.52
3ol

k.ok

2,90

^•95
3.57

17.71
1^.57

2.76
2. U9

6.3U

6.01

2O.3U
19-35

25.57
23.52

53.56
57.66

19.50
16.97

White ash, :

sp. gr.O. 81 :

Sapwood :

Springwood:

Sumraerwood:

310 :

311 :

5-3^ ■

3.5^ !

7.35"
6.85

8.38:
7.3^;

22.95
19. 6U

2.7U
2.1+1

5. SO:
5.7^

20.17.
20.52.

23.9^
20.83

52.3^
57.^7

18. 56
1^.33

R950

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UNIVERSITY OF FLORIDA

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3 1262 09216 2667