September, 1930
IiL'DUSTRIdL A S D EXGINEERIIL'G CHEMISTRY
develop an industrial process for producing KCl from polyhalite by extraction with saturated salt solutions. Acknowledgment
The help of L. Clarke and B. A. Starrs, assistarit chemists of the New Brunswick station, in connection with the work on process 3 is gratefully acknowledged. Literature Cited (1) Hoff, van't, "Zur Bildung der ozeanischen Salzablagerugen," p. 16 (1905).
94 1
(2) HOE, van't, "Untersuchungen iiber die Bildungsverhaltnisse der ozeanischen Salsablagerungen," Akademische Verlagsgesellschaft. Leipzig, 1912. (3) International Critical Tables, Vol. IV, p. 349; gives equilibrium data. (4) Ibid., p. 362. (5) Klooster, van, J . Phys. Chem., 21, 613 (1917). (6) Levi, Z . phys. Ckem.,106, 93 (1923). (7) Mansfield and Lang, Am. Inst. Mining Met. Eng.. Tech. Pub. 212 (February, 1929). (8) Schaller and Henderson, Mining Met., 10, 197 (1929). (9) Starrs and Clarke, J. Phys. Ckem.,34, 1058 (1930). (10) Starrs and Storch, submitted to J . Phys. Chem. (11) Storch and Clarke, Bur. Mines, Repfs. of Investigations 3002 (1930). (12) Weston, J . Chem. Soc., 121, 1223 (1922). (13) Wroth, Bur. Mines, Bull. 316 (1930).
The Cooking Process 11-Cooking Wood with Sodium Carbonate' S. I. Aronovskyz and Ross Aiken Gortner DIVISION OF AGRICULTURAL BIOCHEMISTRY, MINNESOTA AGRICULTURAL EXPERIMENT STATIOX, ST.PAUL,511".
H E first paper of this Aspen sawdust was cooked with 20 and 40 per cent w0rk-i. e., 3 to 100. The sodium carbonate (based on the weight of the ovencooking procedure, methods series ( 1 ) showed that cooking wood w i t h dry wood) at temperatures of 170" and 186' C. and of preparing the productsfor analysis, and m e t h o d s of water has a very appreciable for 2 and 12 hours. The residues were analyzed for lignin, pentosans, cellulose, and abha-cellulose. analysis were the same as effect on the various constituents of the wood. 'It was Total organic matter, volatile acids (as acetic acid), outlined in the r e p o r t on found that the pentosans and lignin (72 Per cent HzSO4) determinations were the water cooks. were almost completely remade on the residual black liquors. The results of The data are tabulated moved from the wood, being these analyses were compared with those obtained in T a b l e s 1 to VI and partly reduced to furfural by cooking wood with water only, and it was found shown graphically in Figures and p a r t l y d e s t r o y e d to that, under the conditions employed in this work, 1 to 3, form gaseous products. sodium carbonate has a considerable effect on the Results and Discussion Some of the total celluresultant yields of residual wood and its main conlose, as well as the alphastituents. Sodium carbonate cannot be considered RESIDUALLIQUORS-The as an inert ingredient in a cooking liquor. residual liquors from all cellulose, was hydrolyzed t h e sodium c a r b o n a t e to sugars and broken up to form gaseous products. The lignin was prtrtially re- cooks were reddish black and alkaline to litmus paper. moved by the water, but there was practically no loss After standing for 2 weeks no solid matter had sepaof this constituent, as determined by the 72 per cent rated. On filtering these liquors the filter paper assulfuric acid method. It was found, however, that part of sumed a red color similar to that obtained in the water the lignin remaining in the residual woods had become soluble cooks. Total Organic Matter. The total organic matter was obin alcohol, pointing tJo a probable depolymerization of this tained by determining first the total solids and then the total substance taking place in the cooking process. Sodium carbonate, which is present in small amounts in soda as sodium sulfate, and finally subtracting the latter as t'he soda, sulfate, and neutral sodium sulfite cooking liquors, sodium carbonate from the total solids. The quantities of is considered a t present to be inert in so far as the cooking total organic matter thus obtained were substantially higher process is concerned. However, since it is found in all the than in the corresponding water cooks, as shown in Table I alkaline cooking liquors used in commercial practice, it was and Figure 1. Increasing the quantity of sodium carbonate used as the first chemical in a continuation of the investiga- and the time and temperature of cooking resulted in increased yields of organic matter in the residual liquors. tions on the cooking process. Lignin. The quantities of lignin (as determined by the Experimental 72 per cent sulfuric acid method) in the residual black liquors Eight cooks were run, using temperatures of 170" or 186" C. of the sodium carbonate cooks were much larger than in the (100 and 150 pounds :pressure, respectively), cooking duration corresponding water cooks, as shown in Tables I1 and I11 of 2 or 12 hours, and concentrations of 20 or 40 per cent and in Figure 1. The increase in the time and temperature sodium carbonate, on the basis of the oven-dry weights of of cooking and in the concentration of the salt all tended to the wood. The wood used was aspen, in sawdust form, from increase the quantity of lignin in the residual liquor. Reducing Sugars. Only a trace of reducing sugars could the same batch prepared for the series of water cooks ( 1 ) . The ratio of wood to liquor was the same as in the previous be found in the residual liquors of the sodium carbonate cooks. This was to be expected, however, since sugars are very 1 Received June 14, 1930. To be presented before the Division of Celluquickly destroyed in an alkaline medium. lose Chemistry at the 80th Meeting of the American Chemical Society, Cincinnati, Ohio, September 8 t o 12, 1930. Published with the approval of T/'o/,ati/,eacids (as acetic acid). The total volatile acids the Director as Paper 945. Journal Series, Minnesota Agricultural Experi(calculated as acetic acid) in the black liquors of this series ment Station. * Cloquet Wood Products Fellow, University of Minnesota. Fellow- of cooks were remarkably high, increasing to Some extent with the increase in the quantity of sodium carbonate (Table ship established by the Ihrthwest Paper Company of Cloquet, Minn.
T
INDUSTRIAL A N D ENGINEERING CHEMISTRY
942
I11 and Figure 1). The time and temperature of cooking seemed to have no marked effect except in the case of cook 28, where 11.36 per cent of volatile acids, on the basis of the weight of oven-dry wood, were obtained. This amount is greatly in excess of the quantities of volatile acids generally obtained by destructive distillation of hardwoods (4 to 7 per cent of the weight of wood), or in the soda or sulfate commercial cooks (4 per cent on the basis of the wood) (4). It Fore nearly approaches the yields of volatile acids obtained by fusing the wood with sodium or potassium hydroxide, in which case the ratio of alkali to wood is 3 to 1. Table I-Yields
_sTERl
16
12
170
12 12 2
170 170 186
27 29 21
2 2 12
186 186 186
30 28
12 12
186 186
l4y
On basis1 Wt. original 0 . D. I wood 1
Hz0 only 18.0 36.0 HzO only 18.0 36.0 HzO only 18.0 36.0
"
I
"K
On basis Wt. original Wt, 0 . D. wood I
On basis original 0. D. wood
Grams % Crams 1 9 . 2 1 ~2 1 . 3 9 6.9
7.67
%
68.82
18.49 20.59 19.93 22.19 14.98C 1 6 . 6 8
7.7 9.0 13.0
8.59 9.99 14.50
6 0 . 9 67.82 5 5 . 6 61.92 61.6 68.60
21.05 23.44 23.63 26.31 16.31C 1 8 . 1 6
7.8 10.6 11.9
8.74 11.77 13.24
59.7 66.48 5 4 . 6 60.80 54.5 60.69
22.65 25.22 25.94 28.89 15.90C 1 7 . 7 1
7.4 9.3 19.4
8.30 10.31 21.60
5 6 . 2 62.58 5 2 . 5 58.46
21.90 24.39 27.63 30.77
11.7 9.7
13.03 10.77
61.8
20 per cent of weight of 0. D. wood added to digester (HzO, 3350 grams). b 40 per cent of weight of 0. D. wood added to digester (HzQ, 3350 grams). c Organic matter in residual liquors from Tvater cooks was obtained by adding total dry matter found with furfural present in digester condensates.
T a b l e 11-Distribution of L i g n i n in Residual Woods a n d Residual Liquors NOT ACCOUNTED NazCOs IN IN IN FOR COOKTIME TEMP. TOTAL ORIGINAL On basis DIGESTER W O O D LIQUOR WOOD Wt. original lignin
,;& sIzAi
Hrs. 13 31 32 16 33 34 17 27 29 21 30 28
2 2 2 12 12 12 2 2 2 12 12 12
O
C. Grams
170 170 170 170 170 170 186 186 186 186 186 186
curves for lignin and volatile acids in the residual liquor, Figure 1, reach practically the same maximum. DIGESTERCONDENSATE-The digester condensates, obtained in reducing the pressure in the autoclave, were colorless and contained no furfural. This was to be expected in an alkaline cook.
of Residual Woods a n d T o t a l Organic M a t t e r in Residual Liquors
ADDED COOKTIMETEMP.TO DI-
33 34 17
Vol. 22, No. 9
Grams Grams 17.79 5.77 12.22 6.92 10.54 8.16 17.97 4.29 10.83 7.84 7.59 9.62 17.70 4 . 9 5 10.43 8.84 18.0 36.0 7.32 10.55 HzOonly 1 8 . 5 6 5 . 1 0 9.04 8.17 18.0 36.0 8 . 2 8 10.39
HzOonly 18.0 36.0 HzOonly 18.0 36.0 H20only
Grams 23.56 19.14 18.70 22.26 18.67 17.21 22.65 19.27 17.87 23.66 17.21 18.67
Grams ;rams % 23.80 0 . 2 4 1.01 20.69 1 . 5 5 7 . 4 9 20.69 1.99 9.62 23.80 1.56 6 . 5 5 20.69 2.02 9.76 20.69 3 . 4 8 16.82 23.80 1.15 4 . 8 3 20 69 1.42 6.86 2 0 . 6 9 2 82 1 3 . 6 3 23.80 0 . 1 4 0 . 5 9 20.69 3 . 4 8 16.82 20.69 2 . 0 2 9.76
The mechanism of the production of volatile acids by means of cooking wood with sodium carbonate appears to be mainly one of saponification, for the time of cooking had but little effect. on the yields of acids. It is seen from Table I11 and Figure 1 that an excess of sodium carbonate was used, in so far as the acid yields are concerned, since the increase in concentration of the salt from 20 to 40 per cent of the weight of wood did not produce proportionately larger quantities of acid. It must therefore be concluded that the largest portion of the volatile acids obtained must be formed very early in the cooking process from acetyl groups which are easily saponified, and that the remainder comes from the decomposition and saponification of the more stable constituents of the wood. It is interesting to note that the
0
$ON,, Cdlrg
%n.-2H-s
10
co, Cod",
%.qa -186Z
0
20 Cr.hrj%-*
-1ZH-s
N4C0, t o d o g 6-p
40 -186'C
Figure 1-Yields of T o t a l Organic Matter, Lignin, a n d Volatile Acids (as Acetic Acid) in Residual Liquors The organic matter in the residual liquors from the water cooks was obtained by adding the total dry matter found with the furfural present in the digester condensates. All data based on original charge of 100.0 grams air-dry (89.8 grams oven-dry) aspen wood.
RESIDUAL TVooDs-The dried residues of the sodium carbonate cooks were lighter in color than those of the water cooks. The products obtained by cooking with 40 per cent sodium carbonate were somewhat lighter in color than those obtained with 20 per cent, the other cooking conditions, time and temperature, remaining equal. The color of the residual wood from cook 32 (2 hours, 170" C., 40 per cent sodium carbonate) was approximately the same as that from cook 10 (4 hours, 148" C., water only). The color range of the residual woods from these cooks was as follows: COOK 32 31 29 and 34 27 33 30 28
RELATIVE COLOR Light grayish brown Darker
-4,
Brown (approximating color of cook 16, 12 hours, l i O o C . , water only)
If the presence of oxygen in the autoclave results in a darker residue, then the lighter color of the residues from the sodium carbonate cooks may be attributed to the fact that less lignin was left in the residues of this series than in those of the water series of cooks. The negligible quantities of the very dark alcohol-soluble lignin products remaining in the residual wood were undoubtedly another factor that apparently resulted in the lighter-colored residues of the sodium carbonate cooks (Table V). The residual woods from the cooks run with the salt seemed more pliable than those from the corresponding water cooks. No attempt was made to beat the pulps or to make hand sheets from them. The yields of residual wood in the cooks using 20 per cent sodium carbonate were not materially different from those of the corresponding water cooks (Table IV, Figure 2). Forty per cent sodium carbonate, however, reduced the yields considerably.
INDUSTRIAL AND ENGINEERING CHEMISTRY
September, 1930
T a b l e 111-Distribution
COOK
TIME
13 31 32
Hours 2 2 2
33 l6 34 17 27 29 21 30 28
12 13 2 2 2 12 12 12
12
of Lignin, Volatile Acids, a n d R e d u c i n g Sugars i n Residual Liquors
LIQUOR Na2COsT~~~~ oRGANICLIGNININ RESIDUAL TEMP. ADDEDTO IN On basis On basis DIOESTER Weight total organic original matter 0 . D. wood
R~"s,'~~~L
C. 170 170 170 170 170 170 186 186 186 186 186 186
Grams HzOonly 18.0 36.0 HzO only 18.0 36.0 H20only 18.0 36.0 Hz0 only 18.0 36.0
Grams 19.21 18.49 19.93 14.98 21.05 23.63 16.31 22.65 25.94 15.90 21.90 27.63
1
Gvams 5.77 6.92 6.16 4.29 i.84 9.62 4.95 6.84 10.55 18.10 8.17 l(l.39
%
%
30.04 37.43 40.94 28.64 37.24 40.71 30.35 39.03 40.67 32.08 37.31 37.60
6.43 7.71 9.09 4.78 8.73 10.71 5.51 9.84 11.75 5.68 9.10 11.57
T a b l e IV-Yields of Residual Wood a n d I t s Main C o m p o n e n t s (Based on original charge of 89.8 grams oven-dry aspen sawdust.) NazCOa
COOKTIMETEMP.ADDEDTO
DIGESTERWOOD
Hrs. C. Original wood 13 2 170 31 2 170 32 2 170 16 12 170 33 12 170 34 12 170 17 2 186 27 2 186 29 2 186 21 12 186 30 12 186 28 186 12
Grams HzOonly 18.0 36.0 HzOonly 18.0 36.0 HzOonly 18.0 36.0 HzOonly 18.0 36.0
I N RESIDUAL WOOD
RESIDUAL
Grams 89.8 63.7 63.6 60.9 61.8 60.9 55.6 61.6 59.7 54.6 54.5 56.2 52.5
943
Li,gnin
Pentosans
Cellulose
Grams 20.69 17.79 12.22 10.54 17.97 10.83 7.59 17.70 10.43 7.32 18.56 9.04 8.28
Grams 15.80 2.75 8.91 8.29 1.40 7.62 7.22 1.56 7.12 6.98 0.21 6.59 6.67
Grams 55.86 44.23 49.14 48.61 42.40 48.39 46.46 42.68 46.35 45.06 34.87 45.49 42.34
a-Cellulose
Grams 41.36 37.66 34.53 32.07 34.11 32.10 32.14 35.40 32.31 25.93 22.49 26.63 18.85
The amounts of the wood apparently destroyed in the cooking process-i. e., the difference between the oven-dry Fveight of the original woods and the sum of the oven-dry weights of the residual woods plus the organic matter in the black liquors-showed an increase with the increase in concentration of the sodium carbonate except in the case of cooks 28 and 30 (Tables I and VI and Figure 3). I n the latter cooks the increase in sodium carbonate, while resulting in lower yields of residual. wood, gave comparatively higher yields of organic mattter in the black liquor. This may be due to a part of the cellulose being decomposed into nonvolatile acidic substances, probably oxy-acids, uhich combined with the sodium carbonate (6). Lignin. The quantities of lignin remaining in the residual woods of this series of cooks were much lower than in the corresponding series of water cooks, as shown in Table IV and Figure 2 . Although the increase in all three factorstime, temperature of cooking, and concentration of sodium carbonate-reduced the yields of lignin, the salt concentration seemed to have the greater effect. The action of the sodium carbonate in removing the lignin from the wood may be considered in two ways: First, it may combine with the lignin, as such, present in the wood; and second, it may combine with the depolymerization products of the lignin caused by the action of the water. The latter theory appears the more probable because the quantities of benzene-alcohol extracts of the residual woods in this series were much lower than in the corresponding cooks of the water series (Table V). I n the latter series it was shown that the decreases in the lignin content of the extracted residual moods were approximately equal to the quantities of benzenealcohol extractives obtained (1). The amounts of lignin not accounted for by analysis (Tables I1 and VI and Figure 3) were substantially larger than in the series of cooks made with water as the sole cooking agent. The lignin may have broken down to a greater extent
I
VOLATILE ACIDSAS ACETIC IN RESIDUAL LIQUOR
REDUCING SUGARS
On basis On basis Weight total organic original matter 0 . D . wood
RESIDUAL LIQUOR
R
Grams 1.77 6.78 8.44 1.58 7.69 8.40 1.34 7.74 8.71 1.60 7.74 10.20
IN
Grams 11 33 Trace Trace 2.35 Trace Trace 4.47 Trace Trace 2.83 Trace Trace
%
9.21 36.67 42.35 10.55 36.53 35.55 8.22 34.17 33.58 10.06 35.34 36.92
1.97 7.55 9 40 1.76 8 56 9 35 1.49 8.62 9.70 1.78 8.62 11.36
than in the water cooks, due to the presence of a larger quantity in solution, or the presence of sodium carbonate may have caused a disruption of the constitutional groupings of the lignin which tend to prevent the solution of the latter in 7 2 per cent sulfuric acid. Pentosans. The quantities of pentosans remaining in the residual woods of this series of cooks were much larger than those remaining in the corresponding cooks of the water series (Table IV and Figure 2 ) . Under like conditions of time and temperature of cooking, an increase in the concenWaid ((r
1
*ffi
1
$ 5 $ 4
d.x
e> 2
4
+Z'M0. Cos'
",Tme
2Hr3
c 0, Crring>rp
4c
/66 C
4 0
C
i 01
I
I7 Hr.
4'
cM,cc, CaoInr
Enr
166
r
Figure 2-Yields of Residual Wood a n d I t s Components Zero per cent NazCOs represents cooking with water only. All data based on original charge of 100.0 grams air-dry (89 8 grams OVen-dryi aspen wood.
tration of sodium carbonate from 20 to 40 per cent of the weight of'wood had very little effect on the pentosans in the residual woods. This action of the sodium carbonate in conserving some of the pentosans was probably due to its neutralization of the organic acids, formed when water was the sole cooking agent, that tend to destroy the pentosans. The reason that the quantities of pentosans remaining in the residual woods were so uniform can be explained by the fact that these quantities are resistant to neutral or slightly alkaline hydrolysis and are generally found associated with the cellulose by ties that are hard to break, even by chlorination (7). Bray and Andrews (2) showed that in cooking aspen by the soda process the pentosan content was reduced rapidly during the early stages of the cook t o a constant value of 7.7 per cent. This was due to the fact that part of the pentosans in the wood is removed readily by hydrolysis and
INDUSTRIAL AlVD ENGINEERIiVG CHEMISTRY
944
the rest is held in a more stable combination with the cellulose. Owing to accidental mixing of the residual liquors of this series of cooks, it was impossible to determine their pentosan content and, therefore, the loss of this constituent in cooking with sodium carbonate. It is known, however, that alkalies, even at very low concentrations, extract the hemicelluloses from wood. Schorger (5) showed that when aspen wood
Vol. 22, No. 9
wholly to the pentosans which are closely associated with the cellulose and protected by the salt from hydrolysis. Alpha-cellulose. The addition of sodium carbonate to the cooking liquor reduced the amounts of alpha-cellulose left in the residual woods to a considerable extent (Table IV). This loss increased only slightly with time and concentration of the salt a t 170" C., but a t 186" C. the reduction was more pronounced, as shown in Table VI and Figure 3. It was noticed in the determinations of total cellulose that the products of the cooks a t 186" C . were much more difficult to filter and wash, between chlorinations, than those obtained a t 170" C. The same difficulty was met in the gravimetric determinations of alpha-cellulose. These facts and the greater pliability of the residual woods show that more of the true celluloses were changed over into the alkali-soluble varieties-betaand gamma-celluloses-by cooking with sodium carbonate than when water was the sole cooking agent (Table VI, Figure 3). Table VI-Main C o m p o n e n t s of Wood Apparently Destroyed in Cooking Process N o t Accounteh For in Analysis of Residual $ood a n d Cooking Liquors (All figures on basis of quantities of these components in original wood.) CENT OF ORIGINAL CONSTITUBNTS NOT N a ~ ~ PER I ACCOUNTED FORB Y ANALYSIS COOKTIMETEMP. Wood LigPentoCellu- a-CelluGESTER nin sans" lose lose
Hrs. 0
.,Carkmg Tm. -2 H n .
40
f o Ne. CO. , - -
0
.'.~ C d m g 7&p./BC'C.
Coobig 7 7 m c - l 2 H c ~ .
40
CooAmy TIrp -186.C.
of C o m p o n e n t s of Uncooked Wood Destroyed in Cooking Process The loss of pentosans is based on analysis of residual wood only.
Figure 3-Percentage
was ground in a ball mill with 1 per cent sodium hydroxide for three successive periods of 48, 24, and 18 hours, 61.86 per cent of the total pentosans was removed. Fromherz (3) isolated hemicelluloses by heating wood with water to 180" C. It appears, therefore, that the pentosans removed from the wood were probably retained in the liquors without serious loss or decomposition. Table V-Relation between Benzene-Alcohol Extractives a n d Chlorine C o n s u m p t i o n of Wood (All figures based on weight of wood used for analysis.) ~
I
~~
CHLORINE CONSUMPTION I N
CELLULOSE DETERMINED NarCOs BENZENEChlorine COOKTIME TEMP.ADDEDTO ALCOHOL DIGESTER EXTRACT Total consumed w",d ~~~~~
Hrs. C. Original wood 13 2 170 31 2 170 32 2 170 16 12 170 33 12 170 34 12 170 17 2 186 27 2 186 29 2 186 21 12 186 30 12 186 28 12 186
Grams
%
%
%
%
H20only 18.0 36.0 HzOonly 18.0 36.0 HzOonly 18.0 36.0 H20only 18.0 36.0
2.37 8.82 1.37 1.27 10.93 1.57 1.09 11.48 2.71 1.06 13.71 2.34 1.28
21.95 20.09 17.25 14.48 19.32 14.14 12.10 18.39 15.45 9.78 20.46 11.96 10.82
15.53 13.25 10.20 9.02 11.81 9.20 7.77 11.49 8.90 5.87 13.07 7.44 6.43
6.42 6.84 7.05 5.46 7.51 4.94 4.33 6.90 6.55 3.91 7.39 4.52 4.39
Cellulose. The cellulose contents of the residual woods from the sodium carbonate cooks were uniformly higher than those from the water cooks run under similar conditions (Tables IV and VI and Figure 2). Increasing the salt concentration effected only a small decrease in cellulose content, this loss being slightly greater with increase in the time and temperature of cooking. The increase in the cellulose cont,ents of the residual woods from the sodium carbonate cooks over those from the water cooks can be attributed almost
13 31 32 16 33 34 17 27 29 21 30 28
2 2 2 12 12 12 2 2 2 12 12 12
C. 170 170 170 170 170 170 186 186 186 186 186 186
Grams
%
%
H20only 18.0 36.0 HzOonly 18.0 36.0 HzOonly 18.0 36.0 HpOonly 18.0 36.0
7.67 8.59 9.99 14.50 8.74 11.77 13.24 8.30 10.31 21.60 13.03 10.77
7.49 9.62 6.55 9.76 16.82 4.83 6.86 13.63 0.59 16.82 9.76
1.01
%
%
%
82.55 43.61 47.53 91.12 51.77 54.30 90.10 54.94 55.82 98.67 58.29 57.78
20.62 12.03 12.98 23.90 13.37 16.83 23.40 17.02 19.33 37.42 18.56 24.20
8.75 16.51 22.46 17.35 22.39 22.29 14.23 21.88 37.31 45.51 35.61 54.42
a I n this the figures represent the loss of pentosans from the residual wood only.
Summary of Results
1-Eight cooks, using sodium carbonate solutions as the cooking agent, were made a t 170" or 186" C. (100 and 150 pounds steam pressure) , respectively, for a cooking duration of 2 or 12 hours. 2-The resulting liquors were reddish black and contained larger quantities of total organic matter, lignin (72 per cent sulfuric acid method), and volatile acids than were found in the corresponding water cooks. An increase in the concentration of sodium carbonate from 20 to 40 per cent of the weight of wood affected the yields of volatile acids only slightly, thus pointing to a saponification reaction. %The condensate liquors obtained in reducing the pressure in the autoclave were colorless and contained no trace of furfural. &The residual woods were lighter in color and softer than those obtained from the corresponding cooks of the water series. The yields decreased with an increase in the concentration of sodium carbonate. &There was a greater removal of lignin in the sodium carbonate cooks than in the corresponding water cooks. &The pentosans normally held by the cellulose in a stable association were not removed from the wood by cooking with sodium carbonate. 7-Larger quantities of cellulose remained in the residual woods of this series of cooks than in those of the water series. This was due to the fact that the more stable pentosans associated with the cellulose were not removed by the cooking liquor.
September, 1930
I S D U S T R I A L AND ESGIAVEERIKGCHE-PIISTRY
&The alpha-cellulose contents of the residual woods of the sodium carbonate cooks were generally lower than those of the corresponding water series, and decreased with increasing concentration of the salt. 9-Sodium carbonate in 20 or 40 per cent concentration (based on the weight of' oven-dry wood) cannot be regarded as an inert ingredient in a cooking liquor.
94 5
Literature Cited (1) Aronovsky and Gortner, IND. ENG.CHEM.,92, 264 (1930). (2) Bray and Andrews, Poper Trade J . , 76, NO 19, 49 (1923). (3) Fromherz, 2. physiol. Chem., 50, 209 (1906). (4) Griffin, J. Am. Chem. Soc., 2 4 , 235 (1902). ( 5 ) Schorger, IND. ENG, CKBM., 16, 141 (1924). (6) Schorger, "Chemistry of Cellulose and Wood," p. 405, McGraw-Hill, 1926. (7) Wells, Grabow, Staid], and Bray, Paper Trade J . , 76, No. 24, 49 (1923).
Following Combustion in the Gasoline Engine by Chemical Means' Lloyd Withrow, W. G. Lovell, and T. A. Boyd GENERAL .MOTORSRESEARCH LABORATORIES, DETROIT,-MICK.
Measurements have been made of the oxygen concentration in gases withdrawn from the cylinder of a gasoline engine with a new and improved sampling valve which was located a t different places in the combustion chamber and opened a t different times during the combustion of the charge. Under the conditions defined in this investigation the combustion process In the gasoline engine consists of a narrow combustion wave which proceeds from the spark plug through the combustion chamber a t a finite rate. The combustion zone travels a t a greater rate and follows a different type of acceleration curve through the middle portion of the combustion chamber than along the side walls of the combustion chamber. Over the range investigated the average speed of the . . . . . a
I
N THIS investigation an auxiliary sampling valve which
could be opened at any desired point in the cycle was used to obtain information concerning the chemical reactions between gasoline and air in the combustion chamber of a gasoline engine. This method of experimentation appears to have been developed first by Brooks (1 ), who used it in connection with an oil injection engine. A sampling valve of a design similar to that employed by Brooks was developed independently in this laboratory by Lovell, Coleman, and Boyd @),who used it for studying the rate of burning of the charge in a gasoline engine. Note-In the Bulletin of the American Petroleum Institutefcr 1927, No. 20, R. A. Millikan and W. M. Zaikowsky announced their intention of using a sampling valve in connection with Project 11, "Analysis nf the Gradual Oxidation Prior t o Ignition of Fuels in Internal Combustion Engines and To date, however, the the Relation of Such Oxidation t o Detonation." authors of this paper have not seen a detailed description of Ihis apparatus. Ricardo and Thornycroft, World Power Conference (London), Vol. 111, p. 662 (1928),report the discovery of partial oxidation of fuel in a petrol engine prior to ignition by means of a sampling valve, but. these writers do not describe their sampling apparatus.
I n this latter study the rate of burning of the charge in the combustion chamber was measured by making a chemical analysis of samples which were emitted from the sampling valve when it was adjusted to be open for a short interval a t various times during which the actual combustion process mas going on. The results of these analyses were plotted against the various angles of revolution at which the valve was adjusted to open and curves were drawn. The slopes of these curves apparently gave some information about the rate of 1 Received June 7, 1930. To be presented before the Division of Petroleum Chemistry a t the 80th Meeting of the American Chemical Society, Cincinnati, Ohio, September 8 t o 12, 1930.
combustion zone increases with the engine speed. The progress of the combustion zone is unaffected by a change in spark timing or by the addition of sufficient lead tetraethyl to the fuel to stop detonation until after it has traveled the greater portion of the distance across the combustion chamber. The disturbance which is known as the knock or detonation is confined to that part of the charge which burns last. With respect to events in the latter portion of the combustion space where detonation occurs when it is present, definite conclusions about the differences between the characteristics of normal and detonating combustion must await the results of further experiments which are under way.
....... decrease of the concentration of oxygen and the rates of increase of the concentrations of hydrogen, carbon monoxide, carbon dioxide, and water while combustion was taking place in the combustion chamber. From the shapes of these curves it was concluded that the combustion reaction was of considerable duration and that after some sort of a flame spread the entire charge to the rear of the flame front burned more or less homogeneously. These results appeared very promising and indicated that the sampling valve could be a powerful tool for this type of investigation. Since the publication of this earlier work, however, it has been discovered that the sampling apparatus described therein was not well suited to such an investigation. By means of an electrical valve-interval-deterinator, which was afterwards incorporated as an essential part of the sampling apparatus and which is described below, it was found, first, that the sampling valve opened from 5 to 10 degrees of revolution of the crankshaft after the angle of revolution at which it was set to open; and second, that the sampling valve remained open for 20 or more degrees of revolution of the crankshaft instead of 2 degrees. Since the performance of the sampling valve must be considered in interpreting the results of analyses of samples taken from the engine, considerable time and effort have been expended to develop a sampling mechanism which would permit proper correction for these errors. After a careful analysis of the types of mechanism which would open and close a sampling valve in as short an interval as possible and still remove a suitable portion of the gas from the combustion chamber during each compression cycle of the engine, a new sampling valve and a new mechanical device for actuating this valve were designed.
