Distribution of Lignin in Wood' Microscopical Study of Changes in Wood Structure upon Subjection to Standard Methods of Isolating Cellulose and Lignin By George J. Ritter 1V"llliST P X 0 U " C I S
L*s"x*r"K",
M*"LS"N,
W.S.
T THE Washimgtoir meet,ing of the A h i c l t i c ~ \ ;C H E ~water for 5 hours, after which microtome sections5 24, 36, ICAL SOCIETY, April, 1'324, Ritter aiid Fleck reported and 50 niicrons thick were taken off. The sections were some analytical results on wood, an outrt.anding fcat- extracted with a warm alcohol-benzene solution for 4 hours, ure of which was the higher yield of lignin in springwood th;tn then washed with 95 per cent aleohol and preserved in a 50 in summerwood. Since the middle lamella is of generally per cent water-alcohol solution. Observation wag first centered upon the behavior of the constant thickness, and since the cell walls are thiniier in springwood than in summerwood, it was suggested that t,lie iriiddle lamella during a standard process for preparing middle lamella2 contains a much higher proportioil of lignin cellulose. T\"od sections were placed upon a glass slide, chlothan does t.he reinainder of the cell wall. As a m a n s of test- rinated for 3 minutes, and examined under the microscope. ing that hypothesis, it was decided to follow ivitli the micro- The middle 1;tmella changed to a11 orange-yellow color. scope any changes apparent in the wood structure when thin Upon the addition of hot sodium sulfite it changed to a wine sections were subjected to standard analytical methods of (lolnr and slowly dissolved. Three or four such chlorinations, cnch followed hy a hot sodium sulfite extraction, were n e e m isolating eelluluse and lignin. A nioiiograph by Kuoig and Ilump3 dcscribes the behavior. %tryfor its complete removal. St the end of the process the of fruits, cemils, grasses, and Iongitndinal sections of fir d h d o s e residne of a cro8s section of basswood separated into wood xvlien treated rliemically for the scpnration of crlliilose t,Iic following iiidividual parts: the fibers into cross sections aiid ligiiin. A 1riiigit.udirial section, howel-cr, is really very OS cclls; the vessels into large, more or less semicircular, poorly atlapted to slio\viiig whicli parts uf the \wad are :it- ipiral-\vnllcd cells; atid the rnednllary rays into Iongitudi~ial tacked \vlien rellulose or ligiiiii is ilissol\d. In a nmre recciit ray cells. (I'liite 5 ) Different stages of dcligliificat,ioii a r t the cSfoatsof 12 S hydroclrl~~ric a r d ; iilio\\-n iii I'lates 1 t,o 7. paper .ihrmus' diwil It is kiiomn that eelh~losetransrnit,s polarized light; after SI per cent, ciirorninik brown Light brown
Amorphous Structural
4.3 10.6
Xot only do color and foriii indicate t,wo kinds of lignin,
hut the metlioxyl content, clearly point,? to a chemical differ-
Plate 13-Cross Sccflon of Red Alder Hydrolyzed 30 Minufes Alternately with 3 Per cent Aydrochlori~ Acid and 3 Pel centSodivm Hydroride a t 52- t o 54* C. over a Period of 3 Hour8 190 MinUteB with Each Reaeentl
INDUSTRIAL Ai\-D EXGINEERISG CHEMISTRY
November, 1925
ence. (Plates 8 and 9) The percentage of methoxyl (10.8) in the middle lamella lignin of weStern white pine is low when compared with that in the lignin from a number of other woods,* which has been found above 13 per cent. The low yield can be explained by the incomplete removal of cellulosic material, as mentioned in relation to Table I. If thin microtome sections are to be cut from the blocks of lignin for microscopic study, the block cannot be ovendried, but should be slowly air-dried to about 30 per cent moisture content (fiber saturation). This treatment will prevent distortion of the middle lamella. By impregnating the specimens with melted paraffin it was possible, with care, to cut very satisfactory sections. The paraffin not only holds the middle lamella intact but also affords a white background, thus showing distinctly the dark outline of the middle lamella with either ordinary or polarized light. A photomicrograph of such a section is shown in Plate 10, in which some clusters of amorphous cell wall lignin are seen still adhering to the middle lamella lignin. Likewise, an examination of the isolated cell wall lignin shows the admixture of a small amount of middle lamella lignin which has broken away from the honeycomb-like structure in washing. As previously stated, this study will be continued with a view to improving the method of separation, so that further physical and chemical properties of the two lignin forms may be determined.
1197
Determination of Heating Value of Coal in Monel Metal Bombs’ By J. C. Geniesse and E. J. Soop UNIVERSITY OF MICHIGAN. ANH ARBOR,MIcn.
A study of the heat evolved through solution of the monel metal combustion bomb has been made and a correction proposed whereby it is possible to reduce the error to less than 0.4 per cent even with coals carrying over 5.0 per cent sulfur. A bomb of monel metal or apparently one with a nickel lining will give corrected results well within the ordinary limits of accuracy of the method as a whole. This correction involves merely titration of the bomb washings and a knowledge of the total sulfur of the coal.
HE problem of making a combustion bomb or its lining
T
1-By aid of the microscope in following the chemical reaction it appeared qualitatively that the lignin in wood is located in the middle lamella as well as in the other layers of the cell wall. 2-Although the method empIoyed in separating the two kinds of lignin indicates that approximately 75 per cent of the lignin is located in the middle lamella and 25 per cent in the other lagers of the cell wall, in the light Qf considerations pointed out in discussing Table I the former figure seems high and the latter low. 3-The lignin of the middle lamella shows structural forin, the cell wall lignin a n amorphous character. The middle lamella lignin is light brown in color, the cell wall lignin almost black. I n red alder the middle lamella lignin has a methoxyl content of 13.6 per cent, the cell wall lignin, 4.8. I n weatern white pine the middle lamella lignin has a methoxyl content of 10.8 per cent, the cell wall lignin, 4.3 per cent. 4--Chemically isolated lignin has been separated by mechanical means into two forms, of different chemical composition, and the location of these two forms has been determined in the wood structure.
out of some material that resists corrosion or oxidation has been of p e a t interest ever since Berthelot2 introduced modern combustion calorimetry. The material used not only has to withstand the action of sulfuric and nitric acids but must not undergo oxidation in presence of high oxygen concentration. Berthelot’s bomb was extremely expensive because of its heavy platinum lining. Mahler3 in 1891 introduced a bomb with an enamel lining; and in 1894 &water4 described one with a copper lining heavily plated with gold. Later Emerson6 announced the design of a new calorimeter that could be purchased with any one of three different linings-namely, platinum, gold, or nickel. The gold linings were studied by Atwater and the nickel linings by Olin and ’OVilkins.6 The latter report errors as high as 2.47 per cent on a sample of coal containing 4.25 per cent sulfur. The general trend has been to obtain a lining that would not noticeably corrode or oxidize and still be cheap. With this point in mind Prof. A. H. White furnished for t,he use of his classes a t the University of Michigan a bomb made of steel only, which gave good service by virtue of the formation of a coating of dense adherent scale that. decreased further corrosion. One of these bombs was cut into sections after ten years’ use and showed no measurable decrease in thickness of the metal due to corrosion. Later, however, monel metal bombs were selected to replace the steel. Inasmuch as monel metal is not especially resistant to the action of acids, it was thought necessary to determine the amount of corrosion.
Acknowledgment
Esperimen tal
The author wishes to acknowledge helpful suggestions offered by L. F. Hamley and Arthur Koehler of this laboratory
The work was arranged so that two factors could be studied -the age of the surface of the lining and the sulfur content of fuel used. Samples of coal having sulfur contents ranging from 0.76 to 5.74 per cent were taken. In order to study the effect of the condition of the surface on the heating value of any fuel, an old bomb that had been used approximately one thousand times was used. After a number of determinations had been run the inside of the bomb was machined so as to present a new surface. The experimental work was divided into two parts, In the first, a substance of known
Summary
* T H I SJOURSAL,16, 1264 (1923).
Oxygen Aging Test Symposium-Corrections In the article by J. X i . Bierer and C. C. Davis, THISJOURBAL, 17, 860 (1925), the text beginning with the second line on page 864 should read: I n this way the two stocks in the lower part of Figure 6 might be given a n artificial aging test of 3 days and the two compounds be pronounced of similar aging properties. B u t in one case the compound was on the verge of a deterioration so rapid t h a t in another 2 days it would be in bad shape, whereas the other compound would not reach this rapid decline until the ninth day. I n the article by GI’. W. Vogt on page 870, last line of third paragraph, the word “dried” should be “died.” JOHN M. BIERER
1 Presented under the title “Corrosion of hfonel Metal Calorimeter Bombs” before the Section of Gas and Fuel Chemistry a t the 66th Meeting of the American Chemical Society, Milwaukee, Wis., September 10 t o 14, 1923. Received July 11, 1925. 2 A n n . chim.. (51 2% 160 (1881);[61 6, 546 ( 1 8 8 5 ) . a Comfit. rend., 113, 774 (1891). * J. Am. Chem. Soc., 25, 659 (1903). Tnrs J O U R N A L , 1, 17 (1909). 8 Ckem. M e t . Eng., 26, 694 (1942).
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