October, 1923
INDUSTRIAL A N D ENGINEERING CHEMISTRY
cause the natural formation of formic acid, and to determine the amounts thus formed under these varying conditions. Knowing the conditions of time and temperature under which a food is prepared, it should be possible in many cases to make use of surh data to determine whether or not any formic acid which mav be found in the wroduct has been added as such, or has been formed by natural changes.
factor is 0.0975. The results are corrected for a “blank” on the reagents by carrying them through a distillation under conditions identical with the analysis itself. The values obtained for the caramelized samples of cane sugar are listed in the table, and are also expressed graphically in Figs. 1 and 2. I
Temperature
c.
EXPERIMENTAL
145
Samples of cane sugar, 10.0 grams in each case, were heated in loosely stoppered tubes in an oil bath under varying temperatures and for varying lengths of time. The samples thus prepared were analyzed for formic acid by the Fincke methodla which, in brief, consists in steam-distilling 100-cc. solutions of the samples to which 2 grams of tartaric acid have been added. The volume of the sample solution is kept constant by auxiliary heating, and in no case is the volume allowed to decrease appreciably. The vapors are passed through a suspension of calcium carbonate in water and thence through a condenser so that the volume distilled can be determined. After 1500 cc. have been condensed, the calcium carbonate suspension is filtered, the filtrate faintly acidified with hydrochloric acid and boiled 2 hours under a return condenser with 5 to 25 cc. of a solution containing 10 per cent mercuric chloride, 10 per cent sodium chloride, and 15 per cent sodium acetate. The precipitated mercurous chloride is filtered on a Gooch crucible, washed, dried, and weighed. The conversion 8 Z Nahr. Genussm., 21, 1 (1911); 22, 88 (1912); 23, 255 (1912); 26, 386 (1915); Biochem Z , 61, 253 (1913).
1055
167 180 185
190 195
205
220 243
=A =
B
C D E F
G
= = = = = =
H =
Time of Appearance Heating of Sugar Min. after Heatingo 20 B 120 B-C 20 B 35 B-C 80 F-G 20 E-F 50 G 10 B 20 F 30 G 50 H 10 B 20 F-G 10 E 20 G 30 H 45 H 5 c 10
15 20 45
10
--Formic
Acid-
%
F
G G- H H H H
20 5 G-H 20 H 30 H Sugar unchanged Slightly yellow but granular Superficially melted Entirely melted, light yellow Entirely melted, deep yellow Entirely melted, light brown Entirely melted, dark brown Entirely melted, black
Chemistry of Wood’ VI-The
Results of Analysis of Heartwood and Sapwood of Some American Woods By G. J. Ritter and L. C. Fleck FOREST PRODUCTS LABORATORY, U. S . FOREST SERVICE, MADISON, Wirs.
T
HIS report contains the results obtained in the analysis of heartwood and sapwood of ten American woods. The work was undertaken to determine whether there is any uniform difference in chemical composition between sapwood and heartwood in either softwoods or hardwoods. The methods of analysis used are the same as given in the preceding paper in this series.* All determinations were made in duplicate and the average is given in Table I. DISCUSSION OF RESULTS ASH ~o”rEm--There is no general agreement in the relative ash content of sapwood and heartwood in the species examined. EXTR-~CTIVE COXTENT-In general, the extracts of ether, cold water, hot water, and 1 per cent sodium hydroxide are lower in the sapwood than in the heartwood of the softwoods. I n the hardwoods the extractives are lower in the sapwood than in the heartwood of yellow birch, white oak, and yerlow poplar, but the reverse is true of white ash and pignut hickory. Thus, from the standpoint of extractive content in sapwood and heartwood, the hardwoods analyzed are divided into two classes-one class following the order of the softwood, the other following the reverse course. 1 Presented before the Division of Cellulose Chemistry at the 65th Meeting of the American Chemical Society, New Haven, Conn., April 2 to 7, 1923. 2 THIS JOURNAL, 14, 1050 (1922).
ACETICAcrn-The acetic acid obtained by hydrolysis is higher in the sapwood than in the heartwood of both classes of woods. METHOXYL CoNTEm-The relative percentages of methoxy1 in the sapwood and heartwood of the species analyzed cannot be arranged in any general order. PENTOSAN CONTENT-There is a tendency toward higher yields of pentosans in the sapwood than in the heartwood of the species examined. The difference in yields, however, is slight. METHYLPENTOSAN CONTENT-The methyl pentosan content in sapwood and heartwood of the same class is quite uniform. CELLULOSE COXTENT-FOI the relative cellulose content of sapwood and heartwood, the species analyzed, with the exception of yellow poplar, are grouped in a manner similar to that for extractives. All the softwoods examined have higher cellulose yields in the sapwood than in the heartwood. This tends to counterbalance the low extractives in the sapwood. One hardwood group, yellow birch and white oak with high extractives in the heartwood, has high cellulose content in the sapwood. The other group of hardwoods, white ash and pignut hickory with high extractives in the Aapwood, has high cellulose content in the heartwood. The results obtained from the two yellow poplar samples, which are an exception to the foregoing scheme of grouping, can be explained by referring to the condition of the samples.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
1056
Vol. 15, No. 10
TABLE I-ANALYSES
OF SAPWOOD AND HEARTWOOD OF SOME AMERICAN WOODS (Results in percentage of oven-dry (105’ C . ) samples)
------
SPECIES White ash: No. 2 sapwood No. 2 heartwood No 3sapwood No‘ R heartwood -.-. - -~ Yellow poplar: No. 1 sapwood No. 1 heartwood No. 2 sapwood No. 2 heartwood Pignut hickory: No. 1 saowood $0: 2 hgartwood Yellow birch: No 1 sapwood No: 1 heartwood No. 2 sapwood No. 2 heartwood White oak: No. 1 sapwood No. 1 heartwood No. 2 sapwood No. 2 heartwood Bald cypress: No. 1 sapwood No. 1 heartwood No. 2 sapwood No. 2 heartwood White pine: No. 1 sapwood No. 1 heartwood Yellow cedar: No. 1 sapwood No. 1 heartwood White cedar: No. 2 sapwood No. 2 heartwood No. 3 sapwood No. 3 heartwood Incense cedar: No. 1 sapwood No. 1 heartwood
--SOLUBILITY IN--Methyl MoisCold Hot 1% Acetic Pento- Pento- CelluPentoSample ture Ash Water Water Ether NaOH Acid Methoxyl san san lose Lignin san 179 180 181 182
5.34 0 . 6 1 5.45 0.30 4.91 0.57 7.42 0 . 3 2
5.81 6 . 4 1 2,24 3.40 5 . 2 5 7.02 2.12 4.46
1.17 0.43 0.88 0.46
21.77 19.59 21.93 18.97
3.23 2.31 3.70 2.66
4.70 5.36 5.66 5.20
19.86 19.90 20.16 19.87
2.40 2.25 2.63 2.46
50.38 53.56 49.72 53.40
26.95 27.39 27.39 28.38
18.83 16.75 19.67 17.34
1.60 1.34 1.60 1.47
187 188 189 190
4.30 3.79 3.79 3.88
0.48 0.39 0.36 0.33
1 . 2 9 1.98 0.27 1.50 2.08 0 . 4 3 1 . 4 6 2.51 0 . 1 3 1.45 2.89 0.58
56.74 17.70 16.91 17.57
3.12 2.89 3.33 2.73
5.81 5.86 5.89 6.03
18.37 18.47 18.82 19.08
3 . 2 8 58.13 3 . 1 1 59.57 1 . 2 2 58.02 1 . 1 3 59.47
23.08 22.19 23.86 23.69
15.52 14.97 19.01 17.83
2 . 2 1 5 0 . 1 3 30.74 2 . 4 0 61.30 20.20 0 . 7 8 34.32 48.52 1 . 4 7 36.67 4 2 . 7 5
19.13 18.50 17.16 20.58
191 192
3.54 3.90
0.40 4.91 0.45 2.07
6.45 2.95
0.29 0.36
19.11 15.10
3.58 3.08
5.56 5.79
18.18 18.64
1.11 56.08 1 . 0 2 58.81
21.87 1 6 . 9 0 22.86 1 6 . 2 0
1 . 3 0 5 1 . 5 5 21.92 1 . 3 9 59.44 23.74
26.53 16.82
207 208 213 214
4.92 4.76 4.28 4.36
0.26 0.40 0.18 0.23
1.05 4.16 1.74 2.76
1.98 0 . 4 8 5.69 0.81 2.10 0 . 8 8 3.96 0.99
16.77 2 . 3 4 20.51 1 . 7 8 19.78 3.75 21.14 2 . 8 3
5.66 ,5.46 5.47 5.27
21.36 20.37 22.30 23.21
1.66 1.39 1.82 1.07
1.13 1.12 1.71 1.04
52.15 61.17 52.40 53.56
32.90 23.23 26.82 25.00
14.45 15.60 20.78 21.44
209 210 211 212
7.71 7.70 7.09 6.99
0.57 0.43 0.37 0.42
2.55 4.11 7 . 3 3 10.15 4.27 5.73 4.76 6.60
0.46 0.71 0.65 0.62
21.11 25.81 21.69 22.67
3.44 2.59 2.47 2.97
5.95 6.18 6.02 5.64
23.25 21.82 21.72 22.08
0.90 49.53 1 . 5 7 48.68 0 . 9 4 53.18 0.91 52.12
32.34 32.74 31.14 31.30
24.74 24.22 24.81 24.54
0.88 0.58 1.20 0.96
68.07 67.33 53.81 52.96
16.27 11.84 22.63 20.41
16.66 20.83 23.56 26.63
183 184 185 186
4.72 5.30 6.72 4.72
0.86 1.76
0.23 4.87 2.80 7.93
8.55 10.59 10.63 13.56
0.77 0.48 0.65 0.29
4.35 3.94 4.99 4.07
8.03 6.67 9.23 7.88
4.38 4.49 3.34 3.36
35.01 33.06 35.31 32.27
6.25 5.84 5.89 6.33
1.85 1.80 1.65 1.25
76.09 5.93 76.83 3.94 58.18 2 6 . 9 1 57.38 24.75
17.98 19.23 14.91 17.87
193 194
3.90 2.92
0 . 2 3 3 . 5 5 5 . 1 5 5.46 0.42 5.97 7.68 3.62
17.16 19.15
1.68 1.43
4.16 4.60
9.31 8.56
2 . 1 4 5 4 . 2 5 26.51 1 . 0 0 50.23 26.14
6.81 7.12
2 . 0 9 54.56 17.47 2 . 0 2 5 7 . 2 9 22.42
27.97 19.29
195 196
3.97 4.00
0.28 2.13 0.18 2 . 8 8
1.00 1.32
11.72 12.77
2.05 1.53
4.40 4.81
8.47 8.69
1 . 7 5 58.12 1 . 8 5 56.08
7.60 7.78
2.44 2.73
5 4 . 6 1 26.59 . . . 20.17
18.80
11 61 10.79 10.82 10.36
0 . 9 4 65.77 29.86 10.35 1 . 7 2 5 5 . 1 9 31.39 8.52 1 . 1 6 55.02 3 2 . 1 4 8 . 9 5 1 . 5 6 54.42 32.42 7.97
1.77 1.58 1.28 1.32
73.78 0 . 9 9 61.47 2 2 . 2 3 69.17 14.04 55.22 24.74
25.23 16.30 16.79 20.04
12 08 12 04
0 45 0 56
1 24 1 31
50 69 12 98 66.62 11 05
36 33 22 33
0.48 0.72 0.30 2.79
0.96 3 . 2 7
1.42 2.99 2.30 3.49
3.41 4.12
..
197 198 199 200
5.59 6.39 6.02 6.48
2.18 2.82 1.94 3 . 2 2 3.02 3 . 9 6 2.80 4.01
1:44 1.87
11.02 1 . 1 7 11.41 0 . 8 4 1 2 . 7 1 1.11 14.14 0 . 7 4
5.07 5.00 5.23 5.09
205 206
6.46 0 . 4 7 1.92 2.97 7.27 0 . 3 0 4.74 7.08
0.67 4.78
11.16 1 . 3 3 1 9 . 9 9 0.68
5 95 6.21
0.64 0.21 0.48 0.27
11-RATIO TABLE
OF METHOXYL TO
-Lignin---
SPECIES
.... . .. . . . . . ........ . . . . . ... . . . . . .. . . . Bald cypress.. . . . . . . . . . Eastern white pine., .... Yellow cedar. . . . . . . . . . . Southern white cedar., . . Incense cedar.. . , . . . . . . .
Yellow poplar. . Black hickory.. Red alder.. . ,
No.
Ii
1
G
G
1
Sapwood 26.95 27.39 23.08 23.86 21.87 25.97 26.64 35.01 35.31 26.52 29.03 29.85 32.14 34.73
LrIGNlN
C)N
54.86 53.10 50.94 49.18
49 09 44 53
29.03 28.73
34 73 10 14 33 67 11 68
c ) WEIGHT On THE W O O D CHiO ---
OVEN-DRY(106’ r
Heartwood 27.39 28.38 22.19 23.69 22.85 25.68 25.94 33.06 32.27 26.14 28.73 31.39 32.42 33.67
5 8 . 9 1 24.69 20.72 5 6 . 8 8 24.62 21.87 56.57 27.76 22.19 54.93 28.13 21.81
74.67 64.68 55.11 42.45
1 3 . 6 7 11.66 2 4 . 5 8 10.84 28.29 1 6 . 5 0 33.22 24.33
...
PENTOSAN CONTENT OF CELLULOSE-The pentosan content has a slight tendency to run higher in the sapwood cellulose than in the heartwood cellulose, similar to the results obtained in the original wood. METHYLPENTOSAN CONTENT OF CELLULOSE-In general, the methyl pentosan content is slightly higher in the heartwood cellulose than in the sapwood cellulose. A similar relation was found in the heartwood and sapwood of the original samples. ct-, p-, AND Y-CELLULOSE CONTENT O F CELLuLosE-The percentages of the three kinds of cellulose in sapwood and heartwood cellulose cannot be grouped in any definite arrangement. CONCLUSIONS From a study of the data given in this report the following conclusions may be drawn: 1-In softwoods the water, ether, and alkali extracts are higher in the heartwood than in the sapwood, and as a result the cellulose and lignin are correspondingly lower in the heartwood (except lignin in white cedar). 2-On the basis of extractives hardwoods are divided into two groups: ( a ) those with high extractives in the heartwood, and (b) those with high extractives in the sapwood. The former have high cellulose content in the sapwood; the latter in the heartwood. 3-Acetic acid by hydrolysis is higher in the sapwood than in the heartwood of both softwoods and hardwoods.
Both yellow poplar samples showed slight signs of decay in the sapwood. This condition would tend to increase extractives in the sapwood. The results show slightly higher extractives in the heartwood than in the sapwood, which indicates that on the basis of extractives yellow poplar is strictly a member of the first group of hardwoods. If it belongs to the first group, the cellulose content should be higher in the sapwood than in the heartwood, which is not the case. This can also be explained on the basis of the decayed condition which decreases the cellulose content in the sapwood, the reverse of what would be expected in sound yellow poplar. LIGNIN Co”rENT-In softwoods, with the exception of white cedar, the lignin content is higher in the sapwood than in the heartwood. I n the hardwoods all species except yellow poplar have a higher lignin content in the heartwood than in the sapwood. A study of the ratio between methoxyl and lignin is shown in Table 11. A study of the results reveals the fact that the methoxyl-lignin ratio is approximately 50 per cent higher in hardwoods than in softwoods. This ratio averages less than 13 per cent in bald cypress. I n Paper V of this series2it was shown that the methoxyl content of isolated redwood and live oak lignins was approximately 17.5 per cent. Bald cypress lignin could not meet these specifications and, consequently, it must differ in chemical composition from redwood and live-oak lignins.
White ash..
------
IN CELLULOSE Methyl Pentosan Alpha Beta Gamma
Sauwood 4.70 5.66 5.81 5.89 5.56 2.29 5.26 4.35 4.99 4.16 4.40 5,07 5.23 5.96
-
Heartwood 5.36 5.20 5.86 6.03 5.79 5.33 5.26 3.94 4.07 4.60 4.81 5.00 5.09 6.21
CHIO X 100 Lignin Heartwood 19.5 18.3 26.4 25.4 25.3 20.1 20.3 11.9 12.6 17.6 16.7 15.9 15.7 18.4
SaDwOOd i7.4 20.0 25.2 24.7 25.4 20.4 19.8 12.4 14.0 15.7 15.1 17.1 16.2 17.1
