conies when chemistry is sornetliing far greater than such a collection of empirical facts. We look forward to a inore eornplete mastery of these facts in terins of a more comprehensive tlieoretical treatmelit which underlies them a11. We shall learn to understand with iosiglit and forevision tlie fundairicntal bases upon wliicli rests all our knowledge of CONCLUSION reaetious arid reactioii rates, of steremheniistry and valeiire, , and indced our whole toweriiig I t r r i t ~ s t be eisident Erom what IJRS lieeii mitl that in the Iariiily of the sciences t.liere are niany and varied up~i~irtiiniLies str~icture. To the building of such a struct,iire !re can gladly for tlie exeliange of courtesics. Rut the lifc of ii seiencc wclconie our youtli to furt.lier toil and effort. We should cannot consist. only in semice to iit,lier srieiiws. Were CncmiriLgc them tcr undertake the task with broader lioriaons l 1iterat:ure t,liari we oinselves clremistry faced d l i this fut,iire slime s l i f \vvaukl I~econiethe in ecieuce, iri p!dasophy, r ~ n r in Ciiiderclla o? the sciemw and ret,iim to her baseirrent levels brouglit to our work. We should ask of them, also, liigli in t i l e University of Knowledge. I cannot believe that s u c h rourapc and B patierrce that eventirally will bring its owii is her rlestiriy. Within tile limits of Iicr own family cirde reward since "Knowleclgc accionulateth slowly and not in vain, tliere is still iiiueli room for ilevelopiimrt~ arid extension. with new at,t;rirrment new orders (if lieauty arise." Clieniistry is still largely a descriptive, olisei-vational, and W . ~ I V E ~hlarril '12, IDS:~. ~ ~ e a o r ~ halore ied lite Eenersi riiee~iogol tiie mipirical scieriec. We ranilot be well (:ontent until the time I85tli Meeting ni tltr Amcrirnri Cheniicni Kociely, Washingtun. D. C.,Mardl Statcv Tram l m product,ion of 71 per cent of tlic world's petroleum, is a further illustration of the impact of technical achievement 0x1 the conclusions of ecoiiomic geology. The point need not be further cnipliasized since it helurigs, in part, to tlie t h e m e t h e relation of our science to the state.'
1
nerliy,IND.
~ a e~. 1 i m ~ ~ a 6 ,(I!JW. 4si
27 I 31. 1933.
Synthesis of Benzaldehyde from Benzene and Carbon Monoxide under Pressure JUDSON $1.H ~ L L ~ANI) ~ ANY O R M A N W. liiias~;,Ihiversity of Illinois, 1 :rbaria, Ill.
The synthesis of benzaldehyde by reaction, os compressed carDon rrmriozicie with Denzerte in lhe presence of aluniinurn chloride is readily accomplislied. Factors influencing the rale of reaction an,d the yield are studied. The process seems to have commercial possibililies.
D
T S in high-pressure technic during the past dcea,dc have made it possible to synthesize from cheaper raw materials many compounds of industrial irnportance previously made from more expensive onrs. In some cases it has becm feasible also tu use more direct synthtitic xnet~hods instead of multistep, complex pr~icedurcs. The synthesis of henzaldehyde from benzene and carlion monuxidc is o? interest, not only liecause both of these adraiitages are obtained, but dso because tho synthesis and rrietliiids developed iue applicable in tlie produt:t,ioii of a large nuinher of other iiidubtrially important arornat.ie aldehydes. deals with a pro of the F r i e d e l and Crafts reaction s n i t ably imidified. The data presented cover only tho use of alumiimni cliloridc as the catalytic agent; exp e r i m e n t s a r e in progress for the iiivcstigation of o t h e r agents active in this type of reaction. The f i r s t record of air a t t e m p t t o synthesize aldehydes directly from hydrocarbons and carbon monoxide ailpeared in 1897, wheii-Gatter-
inann and Koih (6) rep'xted the preparation of p-tolyialdelryde from toluenr: by treating the Iatter with a mixture of gaseous hydrogen elrbride arid carbon monoxide in the presence of aluminum ellloride and r..oprous c.1iloride. Only a trace of aldehyde was fornietl wlien ~lrnninumchloride \\.as used without cuprnus chloride. Kine years later Gattennanri (5) gave a detailed description of various methods of preparing aromatic aldeliydc~. Using the ahove method (8), l i e prepared o-xylylaldehyde, m-xylylaldehyde. nicsitylaldelryde, r,seudoc,iiniylaldeliyde, and diphenylaldeliyde. Ire also sneceeded in preparirig benzaldehyde from henat:ne in a11 snalogotis manner by using a.lunihm hroiriide instead of aluminum chloride. This general nrethod of p r e p a r a t i o n o f a r o m a t i c aldehydes was patented (4). In a patent granted to B o e h r i n g e r (2) in 1914, an improvement OS the Uatternianii method is described. The s t a t e m e n t is made t h a t good r e s u l t s caii Ire ohtltined in t i m e oases in n4rich t h e Grtttermann pnicess fails to work or gives low yields, if earboii inoiioxide isallowed toact,on the hydrocarborr under pressure in the pres-
I NDUSTR IAL AND ENGINEER IX G CH EMISTR Y
498
Vol. 2% No. 5
mixtures of benzene and aluminum chloride a t various pressures and temperatures. The reaction was found to be quite slow, approximately 24 hours being required to obtain maximum conversion. The yield of product was found t o be a function of the molal ratio of aluminum chloride to benzene and of the temperature. Above 50" C. high-boiling oils were obtained in increasing amounts. The early part of
p h c
s
2 G
.s % 9
e
0
5
FIGURE 2 EFFECT OF WATERON CONVERSION the present investigation was devoted to a study of the above reaction in the vapor phase; the elevated temperatures necessary soon made it obvious that only very low conversions would be possible. All the data reported here, therefore, refer to liquid benzene and benzaldehyde. Id
EXPERIMENTAL PROCEDURE
FIGURE 1. DIAGRAM OF APPARATUS ence of aluminum chloride. Pressures of 40 to 90 atmospheres are reported to give the best results. It is also stated that cuprous chloride is not necessary under these conditions. Yields of 85 per cent of the theoretical, calculated on the basis of aluminum chloride, are claimed to have been obtained in the cases of benzaldehyde, p-tolylaldehyde, and p-chlorobenzaldehyde, prepared from benzene, toluene, and chlorobenzene, respectively. The next year a patent (10) was issued to Longman in which substantially the same statements and claims were made as outlined in the Boehringer patent. In 1927 the I. G. Farbenindustrie obtained two patents (8) that cover processes in which aliphatic and hydroaromatic hydrocarbons were subjected to the action of carbon monoxide in the presence of aluminum chloride at various temperatures below 100" C. and a t different pressures from 100 to 150 atmospheres. These reactions were discovered by Hopff who, in 1931, published the statement that saturated hydroaromatic and aliphatic hydrocarbons, except methane, ethane, and propane, undergo the Gattermann-Koch aldehyde synthesis (7). I n 1929 a British patent was issued to the I. G. Farbenindustrie (9) which differed from the Boehringer and Longmann patents in that small quantities of titanium chloride or mixtures of the latter with other metallic halides were added to the reaction mixture. A small amount of a mineral acid was also added to accelerate the reaction at the start. No records can be found which indicate that any one of these processes has ever been applied commercially. Preliminary work on this reaction CsHs
+ COeCeH6CHO
was performed in this laboratory a few years ago (3). The method consisted in bubbling carbon monoxide through
The most serious difficulty in studying a reaction of this kind under pressure, involving, as it does, solids, liquids, and gases, is to obtain intimate and reproducible contact among the reacting phases. Investigation of the means available for agitation under pressure led to the development of a type of apparatus described in detail in another article (11).
This apparatus consists of a motor-driven stirrer in which the entire motor, including field, armature, and shaft, operates under the full gas pressure used in the reaction, and no stuffing box is necessary t o separate the motor and reaction chamber. The elongated motor shaft extends into the reaction mixture and permits reproducible agitation equal to that obtainable in open vessels at atmospheric pressure. The temperature of the reaction is controlled by a water thermostat as shown in Figure 1. The reaction constituents, benzene and aluminum chloride, are measured and weighed, respectively, into a, glass test tube, 2 inches (5.08 em.) in diameter andJ0 inches (25.4 em.) long; the entire operation is carried out inside a large desiccator box in order to prevent reaction 'D between aluminum chloride P a n d t h e m o i s t u r e in air. L L With the motor running, this tube is then quickly introd u so duced into the pressure apE paratus through the lower opening, the lower head re4 \ placed, and carbon monoxide pressure applied through the d\ J0 gas connection in the upper head. When the desired time d i n t e r v a l has elapsed, the motor is s t o p p e d , the gas within the chamber ex anded .a+ a6 through a valve in t%e tubR d , o a / c / , c,n, ing connected to t,he lower head, and the test tube reFIGURE 3. EFFECT OF ALUMImoved for analysis of its conNUM CHLO R I D E-B E N Z E N E RATIOON CONVERSION tents. 60
40
%
0 2
O B
10
I NDU S T R I A L A N D E N G I N E E R I N G CH E M IST R Y
May, 1933
Since this reaction is especially sensitive to small amounts of water and other substances, the materials used were carefully selected and uniform in all experiments. All benzene samples were taken from one drum of ordinary
71me ;it
2 0 ~ s
FIGURE 4. EFFECTOF TIMEON CONVERSION AT 23" C.
laboratory quality and contained 0.04 per cent water and traces of thiophene. Anhydrous, powdered aluminum chloride used R-as c. P. quality, containing 0.1 per cent iron. Carbon monoxide was prepared from formic acid according t o the method of Thompson (12). The selection of a n analytical method for benzaldehyde was made after testing several proposed in the literature. The one used is based on that of Bennett and Donovan ( 1 ) . After removing the glass tube from the reaction chamber, its contents are transferred as quickly as possible to a 1000-cc. distilling flask containing about 500 grams of crushed ice. If the reaction mass has solidified, it is dissolved in benzene and the mixture poured on the ice. The flask is heated until all the oil which is volatile in steam has distilled over. The distillate is made slightly alkaline with sodium carbonate solution, transferred to a distilling flask, and again distilled until a few drops of the distillate give no test for aldehyde Kith decolorized fuchsin solution. The distillate, consisting of two layers, is diluted with 95 per cent ethyl alcohol until a single phase is formed and then made up to a definite volume in a graduated
0
2
I
rime in noum
FIGURE 5 . EFFECTOF TIMEOK COXVERSION AT
35"
c.
flask using more of the alcohol. An aliquot portion of this solution is then added to an excess of 0.5 N hydroxylamine hydrochloride solution in 80 per cent ethyl alcohol, and the liberated hydrochloric acid titrated with standard sodium hydroxide solution, using bromophenol blue as indicator. If, during the titration, oil separates out, a measured volume (10 to 20 cc.) of alcohol is added in order to redissolve it. Blank titrations must be made, using the same amounts of hydroxylamine hydrochloride, alcohol, and benzene as are present in the sample to be titrated, and the resulting titration is subtracted from the one obtained from the sample.
FACTORS AFFECTINQYIELD
499 O F BENZ.4LDEHYDE
The early experiments in the liquid phase showed that the yield of benzaldehyde is dependent upon several factors among which are (1) amount of water initially present, ( 2 ) molal ratio of aluminum chloride to benzene, (3) time, (4) temperature, and (5) pressure of carbon monoxide. It is obvious that, if a comprehensive study of all possible combinations of these variables is t o be made, a very large number of experiments will be necessary. I n this work the experiments have been selected so that a general outline of the reaction and its limitations may be obtained. INITIAL WATER COXTEXTOF REACTION MIXTURE. The importance of the water content was first appreciated when it was noted that some of the stock benzene gave an appreciably lower yield of benzaldehyde after being dried with sodium. A systematic investigation of this factor showed that the addition of water in excess of that required to saturate the benzene resulted in a surprising increase in yield up t o a n optimum water content. Table I and Figure 2 give the results. The relationship shown here has been developed for only one set of conditions-namely, a molar ratio of aluminum chloride to benzene of 0.3, a pressure of 1000 pounds per square inch (70 kg. per sq. cm.), and a reaction time of 2 hours. The quantities of starting materials used were 60 grams of aluminum chloride and 134 cc. of benzene. TABLEI. EFFECTOF KATER IXITIALLY PRESENT ON CONVERSION
Hz0 ESPT.
CeHsCHO
cc.
45 53 54 55 56 51 52 49 50 47 48
COXVERSION CsHe basis A1C13 basis
FORMED
ADDED
Grams 2.82 1.93 2.82 5.34 27.1 32.9 32.4 30.4 29.9 19.5 17.8
0.0 0.2 0.2 0.5 0.75 1.0 1.0 2.0 2.0 5.0 5.0
%
%
1.77 1.21 1.77 3.34 16.98 20.6 20.3 19.03 18.72 12.23 11.15
5.90 4.03 5.90 11.12 56.6 68.7 67.7 63.4 62.4 40.8 37.2
It is probable that, as any one of the factors is varied, the optimum water content might also be different from that found here. However, all subsequent experiments, unless otherwise specified, were made using this same water content-namely, 1 cc. of water per 60 grams of aluminum chloride. hl0LaR R.4TIO O F ALUMINUMCHLORIDE TO BENZENE. Figure 3 and Table I1 show the results obtained by varying the ratio of aluminum chloride to benzene at three temperatures. This ratio was varied between the values of 0.3 and 1.0. The charge was in all cases 60 grams of aluminum chloride and 1 cc. of water together with the required amount of benzene. All experiments were run 2 hours a t 1000 pounds per square inch (70 kg. per sq. em.) carbon monoxide pressure. TABLE11. EFFECTOF ALUMINUMCHLORIDE-BESZEKE RATIO ON CONVERSION EXPT.
R.ATIO AIC13: CaHs
CONVERSIOX
C6He basis
70
AICIa basis
70
T E M P E R I T E R E , 25' C,
51 52 57 59 58
0.3 0.3 0.5 0.75 1.0
1.54 144 64
0.3 0.6 0.75
167 163 159
0.3
T E M P E R I T T R E . 35'
T E M P E R A T U R E , 50'
20.6 20.3 31.5 48.6 65.4
68.7 67.7 63.0 64.8 65.4
C.
20.5 33.8 39.9
68.3 67.6 53.2
C.
18.6 33.0 39.4
61.9 66.0 52.5
INDUSTRIAL AND EKGIKEERING CHEMISTRY
500
TIME.The rate of the reaction was measured using various temperatures and ratios of aluminum chloride to benzene. The results of the experiments a t 25" C. and 1000 pounds per square inch pressure are shown in Table I11 and Figure 4,a t 35" C. in Table I11 and Figure 5, and a t 50" C. in Table I11 and Figure 6. TABLE111. EFFECTOF TIMEON COXYERSIOS ED3
RATIO hlcla :CsHs
CONVERSIOK CsHe basis AlCh basis
TIME Minutes T E M P E R A T U R E , 25'
%
%
C.
121
0.1
180
0.58
5.8
68 84 88 51 87
0.3 0.3 0.3 0.3 0.3
30 60 90 120 180
0.72 1.22 1.48 20.6 20.9
2.40 4.07 4.93 68.7 69.7
93 100 106 99 101 96 103 104
0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
30 30 45 60 60 90 120 180
1.59 0.95 1.75 31.0 34.4 37.5 37.6 34.2
3.18 1.90 3.50 62.0 68.8 75.0 75.2 68.4
139 67 138 83 137 59 141
0.75 0.75
0.75 0.75 0.75 0.75
37.2 46.3 41.7 48.3 46.6 48.6 46.7
49.6 61.8 55.6 64.4 62.1 64.8 62.2
135 134 81 58 140
1.0 1.0 1.0 1.0 1.0
58.9 65.0 66.4 65.4 61.0
58.9 65.0 66.4 65.4 61.0
151 152 153 154 155
0.3 0.3 0.3 0.3 0.3
0.84 10,27 16.4 20.5 20.75
2.80 34.2 54.7 68.3 69.2
150 146 149 145 148 144
0.5 0.5 0.5 0.5 0.5 0.5
2.40 27.9 31.0 29.6 34.8 33.8
4.80
55.8 62.0 59.2 69.6 67.6
61 63 64
0.75 0.75 0.75
33.1 39.4 39.9
44.1 52.5 53.2
164 165 166 167
0.3 0.3 0.3 0.3
20 60 120 TEMPER-LTURE, 50' 15 30 60 120
6.61 18.43 18.72 18.58
22.0 61.5 62.4 61.9
160 161 162 163
0.5 0.5 0.5 0.5
15 30 60 120
32.8 32.2 33.0 33.0
65.6 64.4 66.0 66.0
156 157 158 159
0.75 0.75 0.75 0.75 0.75
30 60 120 120
37.8 40.4 40.2 39.4 36.4
50.4 53.9 53.6 52.5 48.5
60
0.75
15
30 30 60 60 120 180
15 30 60 120 1RO TEMPERATURE, 35' 15 30 60 120 180
60 60
120
1 F, . .
place rapidly, as i t did after 90 minutes. Accordingly, the above experiment was repeated, adding 1.18grams of benzaldehyde (the same amount as was formed in experiment 88) to the charge. After stirring for 30 minutes under carbon monoxide pressure, the conversion of benzene t o benzaldehyde was 20.4 per cent, approximately the same as was obtained in 2 hours without the initial addition of benzaldehyde. This result indicated that benzaldehyde or the benzaldehyde-aluminum chloride compound acts as a catalyst for the reaction. Similar experiments 30 were made, using a ratio 3 of aluminum chloride to $ benzene of 0.5. Ineach 2 case 0.9 gram of benzalB dehyde mas a d d e d to 2 the charge, which is the 1o average of the amounts formed in experiments $ ,o 93 a n d 100 a f t e r 30 minutes. This resulted 0 in the a c c e l e r a t i o n of rme ~ o v r s ' the rate of reaction as FIGURE6 . EFFECTOF TIME OY is shown in Table IV. COAVERSION AT 50" C . The figures in the l a s t column are taken from the data of Table I11 (at 25' C.). ~
2
I
10
TABLEIV. EFFECTOF INITIALADDITION OF BENZALDEHYDE ON TIMEOF REACTION (45 grams aluminum chloride used) COXVERSION, CeHa BASIS CeHsCHO CeHsCHO NOCeHsCHO TIME FORMED added added ,liinutes Grams % % 15 23.3 32.6 ... 15 24.25 33.9 ... 30 24.6 34.4 1.27 30 24.55 34.3 ... 60 24.5 34.2 32.7 180 23.75 33.2 34.2
C.
15 30 30
C.
Figure 5 and Table 111 (at 35" C.) show that with a ratio of aluminum chloride to benzene of 0.3, the conversion increases rapidly from 1.5 per cent a t the end of 90 minutes to 21 per cent a t the end of 2 hours. The question arose as to why the reaction took place so rapidly after proceeding so very slowly for 90 minutes. To determine whether or not it was necessary to stir the mixture under carbon monoxide pressure during the initial period of 2 hours, an experiment was performed in 71-hich the carbon monoxide pressure was not applied until the charge had been stirred for 90 minutes a t atmospheric pressure. After applying the pressure, the experiment was continued for 30 minutes. The result was practically the same as if the mixture had not been stirred previously a t atmospheric pressure, the conversion of benzene being only 0.60 per cent. It seemed possible, therefore, that a certain concentration of benzaldehyde was necessary before the reaction could take
Yol. 25, No. 5
EXPT. 105 107 108 109 110 111
These results are shown graphically in the dotted curves of Figure 4. When benzaldehyde was added to charges of aluminum chloride and benzene in the ratio of 0.1 to 1, the results were not as striking as for the higher ratios. However, the rate of reaction was slow enough so that its progress could be followed quite readily. The temperature was 25" C. and the pressure 1000 pounds per square inch. The results are shown in Table V. ~~DDITION OF LOWER RATIOOF TABLEV. EFFECTOF ISITIAL BESZALDEHYDE O N TIMEO F REACTIOX
EXPT.
TIME, t
Minutes 15 30 60 90 120 180 300 480
CsH6 CsHsCHO START CsHsCHO FORMED (A) ADDED (2) Xole Grams Xole 0.00195 0.461 1.080 0.00325 0.481 1.073 0.00732 0,487 1.112 0.01034 0.486 1.065 0,01192 1,055 0.479 0,01300 0.472 1.060 0,01800 0.495 1.055 0.01824 1.044 0.472
AT
C6Hs A T T I M Et ( A - z) Ki X 10' Mole 0.282 0,225 0.252 0,239 0.210 0.155 0.123 0.082
The values of K1 were calculated from the integrated expression for a first-order reaction: In
A = A - x
Klt
It is apparent that the specific reaction-rate constant calculated on the assumption of a first-order reaction is substantially constant for the first two hours. As the yield
I N D U S T R I h L A N D E N G I N E E R I ?i G C H E 31 I S T R Y
502
difficult. It is apparent that extreme conditions of pressure and temperature are unnecessary. A pressure of 1000 pounds or less should offer little difficulty in view of the fact that many more complex high-pressure processes operate a t 3000 to 4500 pounds per square inch (210 to 315 kg. per sq. cm.). It is probable that the method of agitation used in this research could be directly applied to large-scale operation with only ordinary problems of design t o be solved. For semilarge-scale batch operation, standard autoclaves could probably be adapted. Because of the anhydrous conditions maintained, corrosion problems should not be serious. I n the present work lead-plated stirrers have worked satisfactorily. The conversion of the process from batch to continuous also seems possible. Benzene and aluminum chloride could be mixed a t atmospheric pressure to form a thick paste which could be pumped by standard equipment (similar to that used in petroleum cracking operations) into a mixing chamber maintained under carbon monoxide pressure. Continuous removal of the reaction product could be accomplished in the same manner. Hydrolysis and distillation of the product involve no new chemical engineering difficulties. The fact that a wide variety of aromatic aldehydes can also be made by this method in the same equipment is an attractive commercial consideration. Economically the process seems feasible. At present, toluene is the starting material for the production of ben-
Vol. 25, No. 5
zaldehyde. This is chlorinated to benzal chloride and hydrolyzed; or chlorinated to benzyl chloride, hydrolyzed, and oxidized with nitric acid. The process yields benzyl alcohol, benzaldehyde, and benzoic acid, and uses toluene, chlorine, and nitric acid. Considerable saving could be effected by changing to benzene as a raw material, since toluene is generally quoted about 50 per cent higher than benzene. Carbon monoxide, even in a pure state, should be relatively cheap. Modern processes for the manufacture of anhydrous aluminum chloride have resulted in a marked reduction in its price. LITERATURE C I T E D
(1) Bennett and Donovan, Anal&, 47, 146 (1922). (2) Boehringer, German Patent 281,212 (Kov., 1914). (3) Dhaliwal, A. S., B.S. Thesis, Univ. Ill., 1928; Berg, H., 313. Thesis, Univ. Ill., 1929. (4) Farbenindustrie vorm. F. Bayer 8: Co., German Patent 98,706 (July, 1898). ( 5 ) Gattermann, Ann., 347, 347 (1906); 357, 313 (1907). (6) Gattermann and Koch, Ber., 30, 1622 (1897). (7) Hopff, Be?., 64B, 2739 (1931). (8) I. G . Farbenindustrie Akt.-Ges., German Patent 512,718 (Sov., 1927); 520,154 (Dec., 1927). (9) I. G. Farbenindustrie AM.-Ges., British Patent 334,009 (July, 1929). (10) Longman, British Patent 3162 (Sept., 1915). (11) Macmillan and Krase, ISD. ESG.CHEM.,24, 1001 (1932). (12) Thompson, J. G., Ibid., 21, 389 (1929). RECEIVEDKovember 14, 1932.
Chemical Lime from Oolite EMERSOK P. POSTE 99 Market St., Chattanooga, Tenn.
F
OLLOWING several years’ experience in the lime business a t Marblehead, near Sandusky, Ohio, Byron Gager disposed of his interests there and in 1893 acquired a property a t Sherwood, Tenn., on which was then in operation a small lime kiln making a product of superior quality. A new two-kiln plant was constructed, and so successful have been the results of the small beginning that the present operations constitute one of the largest lime-producing plants of the South. The outcrop is located on a mountain side in the southern end of the Cumberland system, a t Sherwood, on the main line of the Nashville, Chattanooga, and St. Louis Railroad. The holdings of the Gager Lime Manufacturing Company now constitute nearly 5000 acres.
KATURE OF LIMESTOSE
% CaO AMgO CO, (loea b y ignition) Fe20a and dlnoa
SI02
55.24 0.72 42.06 0.60 0.60
This computes to a much better material than the Tennessee average given above. The deposit as a whole is made up of three layers of very good grade material, with two intermediate layers of lesser value and a top layer of inferior grade, covered with useless overburden. The layers are nearly horizontal and, though not perfectly regular, conform to the following general scheme: GRADE
THICKNESS CaC03 l\fgcOs Feet 5’% % Useless 20 93.3 1.5 22 97.3 0.9 18 , ... . .. 12 97.3 1.2 12 ,., , . , 33 98.0 0.8
Si02
Fez03 and AlnOs
%
%
Overburden The limestone deposits of the southern end of the CumberFair 6.0 1.0 1.1 0.4 Very good land Mountains belong to the carboniferous system, MissisFair and good, and shale . . . , .. sippian age, and in general are known as Bangor limestone. Very good 1.3 0.4 . . . . . .. Fair, and shale The material a t Sherwood is a fine-grained oolite of excellent 0.9 0.4 Very good purity. According to “Mineral Resources of Tennessee” (2), a “fair analysis of limestone used in the manufacture of lime The useful deposit is thus s h o r n to be approximately 120 in Tennessee” is: feet thick, containing a total of nearly 70 feet of first-class % material in sufficiently thick layers to be worked economically. 94.34 CaCO3 Several recent routine quarry samples from the better 2.14 lMgco3 2.26 FejOs and Alios grade of rock gave the following average composition: SiOr
1.26
The purity of the Sherwood outcrop was indicated in “illinera1 Resources of the United States’’ ( 1 ) by the following analysis :
% CaC03 hIgCOs Si02 FeiOs and Alios
98.10 0.79 0.82 0 29
