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. Summary
1-By aid of the microscope in following the chemical reaction i t 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 a n d 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.
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 i t 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
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. I n 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
* 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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INDUSTRIAL Ab-D EiVGl‘NEERIIYG CHEMISTRY
1198
calorific value but free from sulfur was burned and the amount of nickel and copper dissolved was determined. From this the errors due to oxidation of nitrogen in fuels free from sulfur were calculated. I n the second series samples of coal with varying percentages of sulfur were burned in the monel bomb and the amount of nickel and copper dissolved was determined. To check the discrepancies one of the samples of coal was run in a gold-lined Atwater bomb. The calorimetric determinations were made in all cases as recommended in the standard method of the American Society for Testing Materials.’ The thermometer used mas certified by the U. S. Bureau of Standards. Diekinson’s* value of 6329 calories per gram was used for heating value of benzoic acid. After each run the bomb was immediately washed to prevent further corrosion, and the solution obtained was titrated with standard alkali and then analyzed for nickel and copper by the electrolytic method. The errors due to corrosion were determined by using Thomsen’s9 figures for the heats of formation and solution of the salts. For Cu-O-NsO&q and for Ni-O-N105Aq the values are 52,420 and 83,420 calories, respectively. The bomb washings were neutral; therefore, all the oxidized nitrogen must have formed copper and nickel nitrates. The results are given in Table I. It will be seen that the error amounts to only 0.1 per cent. Table I-Combustion of Benzoic Acid in Monel Metal B o m b Heat of 0.1 N combus- NaOH Heat of formation tion to neuCu Ni Cu-0Ni-Oobserved tralize dissolved dissolved NzOrAq NzOrAq Grror Cal. Cc. Gram Gram Cal. Cal. Per cent Run (1) (2) (3) (4) (5) (6) (7)
I n monel bomb with new surface 1 2 3 4 5
6341 6340 6339 6341 6337
0.0 0.0 0.0
6
6326 6329 6333 6339 6338
0.0 0.0 0.0 0.0 0.0
0.0 0.0
In 7 8 9
10
0.0003 0.0004
0.0058 0.3 0.0050 0.3 0.0052 0.4 0.0042 0.5 0.0004 0 0036 0.3 monel bomb used I000 times 0.0010 0.0034 0.8 0.0016 0.0033 1.3 0.0016 0 0032 1.3 0.0016 0.0028 1.3 0.0017 0.0030 1.4 0.0008 0.0006
7.7 7.1 7.4 6.0 5.1
0.12 0.12 0.12 0.10 0.09
4.8 4.6 4.5 4.0 4.3
0.09 0.09 0.09 0.08 0.09
A series of tests was then made on coals with different percentages of sulfur. When a bomb lined with gold or other noncorrosive metal is used, practically all of the sulfur of the coal appears as free sulfuric acid. The standard method calls for titration of this free acid and correction for its heat of formation. When working with a monel metal bomb it
* A.
S. T. M. Standard, 1921. * B u r . Standards. Sci. Paper 230 (1914).
* “Thermochemistry,” Longmaus, Green & CQ. (1908).
Vol. 17, No. 11
was found that part of the acid reacted to dissolve some of the metal. I n the following tests the free acid in the bomb washings was titrated and the copper and nickel were determined electrolytically in order to obtain a check on the method of computation which is described later. Table I1 gives the details of tests on three samples of coal. The corrected heat of combustion is obtained by assuming that the copper and nickel dissolved formed copper and nickel sulfate. It is probable that some nickel and copper nitrates are present in the washings of all runs, but inasmuch as the heats of formation of the sulfates and the nitrates are nearly equal and since the sulfates are the predominating salts, the actual differences amount to only a few calories. The heats of formation and solution of SO*-0-Aq, Cu-On-SOZ-Aq, and Ni-OrSOa-Aq are 2230, 3976, and 4944 calories per gram of sulfur, respectively. The most accurate correction is made by subtracting from the observed heating value the heat liberated by the reaction SO*-0-Aq for all the free sulfuric acid as titrated plus the heat liberated by the reactions Cu-On-SOp-Aq and X-O~-SOrAq for all the copper and nickel sulfates. The heat of formation of 1.7 cc. of 0.1 N nitric acid amounts to only 2.5 calories; therefore, it is disregarded. The amounts of copper and nickel found in solution are given in columns 3 and 4 of Table 11. The corresponding heats of formation and solution of copper sulfate and nickel sulfate are given in columns 6 and 7. The corrected heating values as given in column 8 were obtained by subtracting the corrections in columns 5, 6, and 7 from the observed heating value. The effect of surface may be seen by studying the ratio of the amounts of nickel and copper dissolved in the washings. Runs 6 to 10 and 20 to 23 were made in the old bomb. The ratios of nickel to copper in the washings were approximately 2:1, or directly proportional to the composition of the bomb itself. After machining the bomb to give a fresh internal surface Runs 1 to 5 and 15 to 19 were made, which gave average ratios of nickel to copper of 1O:l and 3.5:1, respectively. The bomb was then used by a group of students for approximately one hundred times, after which Runs 11 to 14 and 28 to 31 were made, giving ratios of nickel to copper averaging 2.5:l. Later tests showed little further change, proving that but a few determinations are needed to bring the surface composition to a constant condition. It is possible to make a correction reducing the error to 0.4 per cent or less if the total sulfur in the coal and the free acids found in the bomb are known. The correction to be applied to the observed heating value in order to obtain the
Table 11-Corrections
Run
Observed heat of combustion Cal. (1)
0.1 N NaOH to neutralize cc. (2)
11 12 13 14
7417 7412 7406 7421
0.4 0.1 1.1 0.3
for Use of M o n e l B o m b w i t h Various Coals Correction for free Corrected Heating value H2S04 as Correction for Correction for heating value corrected Cu dissolved N i dissolved titrated Cu-Oz-SOz-Aq Xi-02-SOz-Aq 1 - (5+6+7) as proposed Cal. Cal. Gram Gram Cal. Cal. Cal. (8) (9) (4) (5) (6) (7) (3) A-Coal containing 1.76 per cent S used 100 times 1.4 17.6 59.0 0.0088 0.0219 0,0097 0.0217 0.4 19.4 58.5 0.0072 0.0201 3.9 14.4 54.2 0.0102 0,0242 1.1 20.4 65.2
B-Cod 15 16 I7 18 19
6474 6494 6507 6482 6481
0.6
1.3 2.0
20 21 22 23
6498 6480 6472 6507
0.2 0.3 0.4 0.0
0,0183 0.0168 0.0192
28 29 30 31
6150 6173 6161 6155
9.0 6.4 7.3 5.9
0.0211 0.0243 0.0245 0.0225
0.9 1.3
0.0127 0.0109 0,0109 0,0094 0,0127
n,0186
Error if proposed method i s used Per cent (10) -0.16 -0.20 -0.16 -0.08
containing 2.90 per cent S with new surface
0.0383 4.6 25.4 103.2 7.1 21.8 105.2 0,0391 0,0399 1.7 21.8 107.5 3.2 18.8 101.8 0,0378 0.0411 4.6 25.4 110.7 C-Coal containing 2.90 per cent S used 1000 times 0.0351 0.7 37.2 94.5 0.0362 1.1 36.6 97.5 0.0385 1.4 33.6 95.6 0,0395 0.0 38.4 106.3 D-Coal containing 5.74 per cent S used IO0 limes 0,0513 32.1 42.2 137.2 0,0597 48 6 160.8 22.8 49.0 148.5 0.0551 26.0 164.8 0.0612 21.0 45.0
6341 6360 6376 6358 6340
6336 6361 6364 6342 6343
6366 6345 6341 6362
6353 6333 6327 6356
5938 5941 5937 5924
5916 ,5926 5917 5905
-0.08
+0.02
-0.19 -0.24
tO.05
-0.20 -0.20 -0.22 -0.09 -0.38
-n.z
-0.34 -0.32
I-VDb-STRIAL AiVD ESGINEERING CHEMISTRY
?;ovember, 1925
correct heating value when using a monel bomb depends upon the following assumptions: (1) The amount of nitrogen oxidized is small and approximately equal to 1.7 cc. of 0.1 N solution. (2) Since the sulfur originally present in coal as sulfate is very small, it is disregarded and the total sulfur of the coal is assumed to be oxidized to sulfur trioxide. (3) Part of the sulfur trioxide remains as sulfuric acid and the rest goes to form nickel and copper sulfates. (4) The amount of nickel and copper dissolved is in the ratio of 2 : l .
Method of Making Corrections
The procedure used in making the correction will be more easily shown by taking a specific example, such as Run 20. When the bomb washings were titrated, only 0.2 cc. of 0.1 N alkali were required. Since the nitrogen oxidized would require 1.7 cc. alkali, this gives a negative 1.5 cc. In other words, 1.5 cc. of the nitric acid reacted with the monel metal. The 1.5 cc. of nitric acid are equivalent to 1.5 X 0.0016 = 0.0024 gram sulfur. The total sulfur, 0.0290 gram, plus the 0.0024 gram = 0.0314 gram sulfur in the nickel and copper sulfates. The correction is l/$ X 0.0314 X 3975 ‘/a X 0.0314 X 4944 = 145 calories. The heating value corrected for copper and nickel dissolved is 6498 145 = 6353 calories.
+
-
1199
The corrected heating values are given in column 9, and the errors if proposed method is used are given in column 10 of Table 11. To check these methods of computation this same coal was tested in an Atwater bomb with gold lining. The average heating values obtained were 6359 calories. The comparison of the heating values obtained by the various methods is as follows: Atwater bomb (gold lining) Monel bomb (with corrections for sulfur and actual nickel and copper dissolved) Monel bomb \suggested correction)
Calories 6369
6367 6353
It will be seen that the results obtained in the monel bomb are within the limits of error of the process as a whole. If Olin and JFrilkW6 values for their coal samples were corrected in a similar way, assuming that all sulfur not titrated as acid formed nickel sulfate, the errors far their five determinations on a coal carrying 4.25 per cent S would be reduced from an average of 2.29 per cent to 0.55 per cent. Acknowledgment
The authors wish to express their indebtedness to Prof. A. H. White for his valuable suggestions.
Vapor Composition Relationships in the Systems Phenol-Water and Phenol-Cresol1 By F. H. Rhodes, J, H. Wells, and G. W. Murray CORNSLL UNIVERSITY, ITHACA, N. Y .
Phenol and water form azeotropicmixtures with miniLehfeldt3 and van der Lee4 N T H E preparation of m u m boiling points. The percentage of phenol in the have measured the vapor phenol f r o m c o a l - t a r constant-boiling mixture decreases with the pressure, p r e s s u r e s of mixtures of fractions the phenol is being 9.4 at atmospheric pressure and 4.4 at 260 m m . phenol and water a t various separated from most of the The concentration of phenol in the distillate remains temperatures, but give no cresol and other tar acids by about constant as long as the concentration in the liquid data as. to the composition Era c t i o n a l distillation. To is below about 85 per cent. Phenol forms “ideal” liquid of t h e v a p o r . Fox and the crude phenol fraction mixtures with each of the three cresols. Barker6 found that phenol water is added and the mixand cresol do not form conture is frozen to crystallize stant-boiling mixtures. the pure phenol h y d r a t e , which is then dehydrated by a final fractional distillation. Experimental I n the synthetic manufacture of phenol the final step in the purification of the material consists of a fractional distillation I n this present investigation the vapor composition reto remove water and other impurities. Hitherto the stills for lationships, a t various pressures, were determined for the use in separating phenol from cresol and in dehydrating phenol following binary systems: (1) phenol-water, (2) phenol-ohave been designed and operated largely on an empirical basis. cresol, (3) phenol-m-cresol, and (4) phenol-P-cresol. The The rational design of such stills is necessarily based on a phenol used was from a mixture of natural and synthetic knowledge of the vapor composition relationships in the sys- phenol which had been purified by recrystallization as phenol tems phenol-water and phenol-cresol, and data in regard to hydrate, followed by careful fractional distillation. The these relationships have not been generally available. purified material melted a t 40.6” C. The o-cresol was prepared from “technical” grade material by repeated fractional Previous Work distillation. It showed a melting point of 30.3” t o 30.5’ C. Published data as to the vapor composition relationships The m-cresol and the p-cresol were purchased in the market in these systems are very fragmentary. Schreinemakers? has and were subjected to no further purification except a fracdetermined the composition of the vapor in equilibrium with tional distillation to remove water and traces of impurities. mixtures of phenol and water a t various constant tempera- The redistilled p-cresol melted a t 33.75’ C. and gave no tritures. In practice, however, the distillation of wet phenol nitro-m-cresol when tested by the nitration test. The reis effected a t substantially constant pressure and not a t con- distilled m-cresol, when tested by the nitration test, showed stant temperature, so that these data are of little direct value 93.4 per cent m-cresol. The impurity was probably p-cresol. in the design and operation of stills for plant use. FurtherI n working with mixtures of phenol and water, from 300 to more, Schreinemakers did not determine the composition of 500 grams of the mixture were placed in a distilling flask the vapors in equilibrium with mixtures very rich in phenol.
I
a Phil. M a g . , [5I 47, 284 (1899).
*
Received June 5, 1926. Z p h > s . Chem., 36, 459 (1900).
4 5
Z.p h r s i k . Chem., 33, 622 (1900). J . SOC.Chem. Ind., 36, 842 (1917)
