• chemistry or WOOD VI. The Results cf Analysis cf tieartiuccd and Sapuicod of Some American Woods October 1923 UNIV. OF FL LIB. DOCUMENTS PEP' U.S. DEPOSITORY mm of mm wm UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE FOREST PRODUCTS LABORATORY Madison, Wisconsin In Cooperation with the University of Wisconsin CHEMISTRY OF WOOri VI — The Results of Analysis of Heartwood and Sapwood of Some American Woods By G. J. RITTSR, Chemist and L. C. FLECK, Associate Chemist This report contains the results obtained in the analysis of heart- wood and sapwood of ten American woods. The work was undertaken to deter- mine whether there is any uniform difference in chemical composition be- tween sapwood and heartwood in either softwoods or hardwoods. The methods of analysis used are the same as given in the preceding papers in this series.— All determinations were made in duplicate and the average is given in Table 1. Discussion of Results Ash content . — There is no general agreement in the relative ash con- tent of sapwood and heartwood in the species examined. Extractive content . — In general, the extracts of ether, cold water, hot water, and 1 percent sodium hydroxide are lower in the sapwood than in the heartwood of the softwoods. In the hardwoods the extractives are lower in the sapwood than in the heartwood of yellow birch, white oak, and yellow 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. Acetic acid . — The acetic acid obtained by hydrolysis is higher in the sapwood than in the heartwood of both classes of woods. Methoxyl content . — The relative percentages of methoxyl in the sap- wood and heartwood of the species analyzed cannot be arranged in any general order. -Presented before the Division of Cellulose Chemistry at the 65th meeting of the American Chemical Society, New Haven, Conn. , Apr. 2-7, 192 3. Pub- lished in Jour. Indus. & Eng. Chem. , Oct. 1923. IS, IO55. 2 -Jour. Indus. & Eng. Chem., Nov. 1922. lif, IO5O. R916 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. Methyl pentosan content , — The methyl pentosan content in sapwood and heartwood of the same class is quite uniform. Cellulose content . — For 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 hard- wood group, yellow "birch and white oak with high extractives'- in the heart- wood, has high cellulose content in the sapwood. The other group of hard- woods, white ash and pignut hickory with high extractives in the sapwood, 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. Both yellow poplar samples showed slight signs of decay in the sap- wood. 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 content . — In softwoods, with the exception of white cedar, the lignin content is higher in the sapwood than in the heartwood. In 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 2. A study of the results reveals the fact that the methoxyl- lignin ratio is approximately 50, percent higher in hardwoods than in softwopds. This ratio averages less than 13 percent in bald cypress. In Paper V of this series- it was shown that the methoxyl content of isolated redwood and live oak lignins was approximately 17. 5 percent. Bald cypress lignin could not meet these specifications and, consequently, it must differ in chemical composi- tion from redwood and live oak lignins. 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. Methyl pentosan content of cellulose .— In, general, the methyl pento- san content is slightly higher in the heartwood cellulose than in the sap- wood cellulose. A similar relation was found in the heartwood and sapwood of the original samples. R916 -2- Alpha-, beta-, and gamma-cellulose content of cellulose . — The per- centages of the three kinds of cellulose in sapwood and heartvzood cellulose cannot he grouped in any definite arrangement. Conclusions Jrom a study of the data given in this report the following conclu- sions may be drawn: 1. 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(U ....2.. 0OO00*j0OOO_,OO00*jO0000-uO0OOBO0 > &* « ? >. £ 5 Digitized by the Internet Archive in 2013 http://archive.org/details/chemivOOfore Table 2. — Ratio of methoxyl to lignin on oven-dry (105° C. ) weight of the wood. : Lignin : CH3O : CH3O x 100 Species : No. Lignin : Sapwood :Heartwood 'Sapwood : Hear two od Sapwood 'Hear two od White ash ( 2 3 26.95 27.39 ' 27.39 28.38 4.70 5.66 : 5.36 : 5.20 17.4 20.0 : 19.5 : 18. 3 Yellow poplar. . ( l 2 23. 08 23.86 22.19 23.69 5.81 5.89 5.86 : 6.O3 25.2 24.7 26.4 25.4 Black hickory. . . . . : 1 21.87 22.85 5.56 : 5.79 25.4 25.3 (J 1 : 2 25.97 26. 64 25. 68 25.94 ■ 2.29 5.26 5-33 5.26 20.4 19.8 20.1 20.3 Bald cypress 1 : 2 : 3^.01 : 35.31 : 33.06 : 32.27 : 4.35 4.99 3.94 4.07 12.4 14.0 11.9 12.6 Eastern white p ine : 1 : 26.52 • 26. Ik : 4.16 4.60 15.7 17.6 Yellow cedar. . . . . . : 1 : 29.03 : 28.73 : k.ko • 4.81 : 15.1 16.7 Southern white (! 2 : 3 : 29.85 ' 32. 14 : 3L39 32. 42 : 5.07 5.23 5.00 : 5.09 17.1 16.2 15.9 15.7 Incense cedar. . 1 34.73 33.67 : 5.95 6.21 17.1 18.4 B.916 UNIVERSITY OF FLORIDA 3 1262 09216 3152