Paper_-_The Lubricant and Asphaltic Hydrocarbons in Petroleum_-_Mabery 1923

The lubricant and asphaltic hydrocarbons in petroleum
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  December, 1923 IND USTRIAL AND ENGINEERING CHEMISTRY 1233 The Lubricant and Asphaltic Hydrocarbons in Petroleum' By Charles F. Mabery CASE SCHOOL OF APPLIED CIENCE, CLEVWLAND, OHIO ALTHOUGH ime hasbeendevoted uch in this laboratory to the composition of the dis- tillable hydrocarbons in petroleum, no attention has hitherto been given here and little elsewhere to the iden- tification of the hydrocar- bons that cannot be distilled without decomposition. Of the few .attempts to sepa- rate these constituents of petroleum by cold solution and precipitation, cold fractionation, the most noteworthy is the work of Charitschoff, who described the following hydrocarbons with their specific grav- ity: C19H38 0.8930; C~ O, 0.9050; CzzHa, 0.9080; C24H.16, 0.9130; C35Hm1 0.9150; and it has doubt- less suggested the frequent allusions to the presence of naDhthene lubricants in This work. is a study of the hydrocarbons in petroleum which cannot be distilled without decomposition. The method used for their separation was fractional solution in a hot mixture of ether and alcohol, after first distilling the crude oil to 300 C first sep- arating the homologs of each series and then dividing the series into fractions. Identification of the hydrocarbons was then accomplished by determination of specific gravity, molecular weight, and percentage composition. This method of separation and analysis was applied to five crude oils, from West Virginia, Pennsylvania, Ohio, Texas, and Russia. The Ohio oil being one of peculiar composition, a study of its distillable constituents as well as of its fractions separated by solution is given. The homologs of the heavier series above 300 C vacuum appear to increase regularly and are divided into 1) the D hydrocarbons, lubricants to the final heavy ends, and (2) the H group, asphaltic in tbe heauy ends. A comparison of the various oils shows a well-defined distinction between the lubricant and the asphaltic hydrocarbons, and the higher specific gravity of the Texas and Russian lubricant hydrocarbons is due to their inherent struc- ture. The wide variation in specific gravity of individual fractions of the heavy crudes indicates the presence of carboxyl acids or esters. Iodine number determinations show that only the ring form of un- saturation applies to the lubricant hydrocarbons, and they do not appear to enter into the formalite reaction as applied by the Mar- cusson method. from the Appalachian oils, the solid residue was dis- solved in ether to a dilute solution, alcohol added until the paraffin began to partic- ipate flocculent, the solution cooled to 0 C., filtered cold, again cooled to -20' C., and again filtered, with very little paraffin remaining in the oil after the first filtra- tion. There is some diffi- culty in reaching the point where flocculent precipita- tion begins without carry- ing down a large amount of the semisolidified oil, HOMOLOG EPARATION- In lots of 1000 to 1500 grams the vacuum residue, free from paraffin, was heated to the boiling point of the solvent in flat, cork- stoppered bottles in a hot water bath with frequent shaking, the stopper being held in with the finger and Gerican petroleum. However, none of the hydrocarbons from Baku oil, described in this paper, contain the series CnH2n, or the CnHzn--2 although some of these specific gravi- ties are about the same as those of the series C,Hz,-8 in Baku oil, to be described later, and none of the varieties ofkAmerican petroleum have shown such composition. Since petroleum hydrocarbons begin to decompose in dis- tillation at about 200 c., nd above 300' c. most crude oils, even under pressures reduced to 20 mm., show evidence of decomposition, it is impossible to separate the constituents of petroloum by any form of distillation that will not distil at 300 C. vacuum. SEPARATION Y FRACTIONAL OLUTION With the exclusion of distillation the only remaining possi- bility appeared to be fractional solution, and, in view of the variations in other physical constants, there seemed to be no reason why the different series and homologs should not possess sufficient differences in solubility to permit their approximate separation in this manner. Trial of the various solvents excluded all but a mixture of ether and ethyl alcohol, and since all the constituents of petroleum dissolve freely in ether, but are quite insoluble in alcohol, it seemed possible to prepare from them a convenient solvent. For general use a mixture of equal parts by volume, with suitable varia- tions for the more soluble lighter ends, and the less soluble constihents of the heavier ends proved efficient for all the varietEes of crude oil. For convenience of reference, the lighter. fractions will be referred to as the higher or upper ends, and tthe heavier as the lower ends of the series or group. Under a pressure of 30 mm. the crude oil was first distilled to 300 C. For the removal of the paraffin hydrocarbons Received December 4, 1922. frequently removed to relieve excessive pressure. For col- lection of the homologs of all the series intotenor fifteengroups, the hot solution was poured off from each extraction and the solvent distilled, the first fractions containing the more soluble upper end, and the diminishing solubility giving the consecu- tive fractions down to thelast residue. For further separation of the series homologs, the lowest group was first heated with the solvent of proper concentration, sufficient to dissolve a considerable part, and the hot solution poured off cooled, and again poured off from the separated oil. To this was added the next fraction, which was again heated, and the solution poured off for the treatment of the next fraction. This procedure was continued to the upper end. The sol- vent distilled off from the last treatment gave the first member of the group, and this procedure was repeated six times. Since the specific gravities of the fifth andsixth fractions were approximately the same, it was assumed that the homologs of all the series were fairly well collected within the respective groups. The efficiency of this method appeared in the differences in consistency between the lowest frac- tions, extremely thick, viscous, or nearly solid lubricants, as in the Appalachian oils, or thick, black, tarry or solid as- phalts, as in the Texas and Russian oils, and the upper fractions, thin, amber-colored lubricants. SERIES BPARATION-Beginning at the lower end of the group each fraction was about half dissolved in rich, hot solvent, decanted, leaving a residual oil, H, the solvent dis- tilled, giving another residual oil D, and this was continued with all the fractions to the upper end. To be sure that a single extraction gave an approximate separation, it was followed by another similar treatment, giving two series, Da and Dh. The specific gravities of a and h proved to be suffi- ciently concordant to indicate a fairly satisfactory separation by the first treatment. ~  1234 INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 15, No. 12 In a second mode of series separation each of the first group fractions was heated to boiling with the solvent, the hot solution decanted, cooled, again poured off from the separated oil and distilled, giving three oils-H, the first residue; C, the residue from cooling; and D, the residue from the distilled solvent. Each of these oils was again treated in a similar manner, and this treatment continued three or four times, thus dividing the srcinal oils into eight or twelve fractions, did not materially change the specific gravity from the results of a single cross separation, from which it was inferred that the marked difference in solubility gave a fairly good sep- aration in the first extraction. The following examples of its application on some of the oils as a means of control show the rapid separation by this method. A top fraction of a Russian vacuum residue containing more soluble, heavier carboxyl constituents brought up from below, and another from the Rosenbury oil, were separated by a single extraction into light and heavier constituents, as follows: 0.9594 H residue hot 0.9198 C esidue'solvcnt cooled 0.8925 D residue: solvent distilled 0.9230 H 0.8908 C 0.8875: Russian fraction, specific Rosenbury (Pa specific gravity 0.9236 gravity 0.90i-i 1 No doubt the petroleum hydrocarbons under the condition of cold solution used by Charitschoff do exert a mutual sol- ubility and interfere with the use of specific gravity as means of identification, but under the influence of a hot solvent it seems to be quite otherwise. The constants relied upon for grouping and identification were specific gravity, molecular weight, and composition by analysis. Determinations of specific gravity, except of the most viscous tars, which were weighed under water by the method of Kirschbraun, were made in a Sprengel pycnometer at 20 C. In the beginning, molecular weights, especially of the heavy hydrocarbons, gave much trouble. Of the common solvents benzene alone at the boiling point was applicable, and this was reliable only with the lower members of the Appalachian oils. Stearic acid at 50 C. proved to be more satisfactory. A weight of oil from 0.3 to 1.5 grams, depending upon the specific gravity of the oil, gave a depression of from 0.150 to 0.400 C. on the Beckman scale. The limitations of the method and the accuracy required for concordant readings are shown by the fact that for molecular weights above 1000, a depression of 0.001 C. corresponds to nearly a difference of the increment, CH2, but below 500 to a difference of only 2 to 4 units. Occasionally, stearic acid gives abnormally high read- ings, doubtless caused by irregularity in the initial separation of crystals, which resisted all attempts toward correction by variation in stirring or other manipulation; but several, usu- ally not more than three repetitions, readily revealed by con- cordant values, could be relied upon for the desired results. In the extremely high values, 1600 or more, that define the hy- drocarbons with the largest molecular weights, the observa- tions were as closely concordant as with the oils having a mo- lecular weight of 300. The commercial acid dried at 100 C. is sufficiently pure; different lots showed small variations in the constant-for example, (1) 4.431, (2) 4.467; Bernstein gives for this constant, 4.5. Particular attention was neces- sary in getting complete solution of the heavy oils, and these required large weights for sufficient depression. To yield the small differences in percentages of carbon and hydrogen necessary to distinguish between the different series, the gases from the asphaltic oils require the highest temperature for complete combustion that the most infusible glass will stand with a stream of oxygen on the copper oxide in front of the oil. Much time was saved by weighing the bulbs filled with oxygen. Although a 50 per cent solution of potassium hydroxide was used, with solid potassium hydrox- ide or soda lime and phosphorous pentoxide in the safety tube of the Geissler bulb, a horizontal tube in front with soda lime and phosphorous pentoxide invariably showed from 0.0005 to 0.0020 gram increase in weight, sufficient, if lost, to spoil the analysis. VARIETIES F PETROLEUM NVESTIQATED General application of the method herein described to the petroleum fields of the world should doubtless involve the study of more than one hundred representativc varieties. In this paper is included the separation of the constituent hydrocarbons from the following five typical crude oils: TABLE Cabin Creek, W. Va. 1st sample 1700 0.8100 25 8683 2nd sample 1700 0.7850 20 8638 Rosenbury, Emblen- ton, Pa. Rosenburysand oose sand 1240 0.5080 35 8852 150 0.9023 80 9076 ecca, Ohio Loose sand 2000 0.9333 40 9580 our Lake, Texas Baku, Russfa Loose sand Shallow 0.8650 35 9270 Lowest Berea grit The Cabin Creek and Rosenbury oils are regarded as the best varieties of Appalachian petroleum, and known in the trade as paraffin-base oils. They contain large proportions of the gasoline, kerosene, and solid paraffin hydrocarbons, leaving residues solid wit& paraffin at 300 C., 30 mm. Au- thentic specimens of these oils, pale yellow in color, were pro- cured for this examination from 0. C. Dunn, Marietta, Ohio. The Sour Lake oil, procured from a reliable source, is a typical heavy Southern crude, containing no CnHm + 2 hydrocarbons; the crystalline hydrocarbons occasionally ob- served in some distillates are probably of a heavier series. That the less volatile portions of the Texas oils are composed to a large extent of the best lubricant hydrocarbons cannot be doubted, and while the balance of the Northern crudes are of the lighter series, a large proportion in the basic South- ern crudes are of the so-called asphaltic hydrocarbons which impart high viscosity to the lubricants containing them. How far the higher specific gravity and viscosity indicate superior lubricant quality depends, of course, on the inherent wearing quality of the asphaltic hydrocarbons, and this has never been precisely defined. In the early development of Texas oil territory it was the synonym for high sulfur petro- leum. Intimately associated with beds of sulfur, the sulfur was dissolved to the limit of saturation, and the resulting chemical changes eliminated hydrogen as hydrogen sulfide with the formation of the heavy hydrocarbons. In the for- mation of such heavy crudes as the Sour Lake, evidently sulfur has been B determining element. With continued production the srcinal proportions of sulfur in these oils, 1 to 3 per cent, have been greatly reduced. The Russian oil is a part of two barrels brought for the author's use twenty-five years ago from Baku. It is less stable than American oils and care is necessary to avoid de- composition, even under reduced pressure. Like all Russian crudes, the distillable portion is composed of the naphthene hydrocarbons that make superior luminants, and the remain- der has a smaller proportion of lubricants than American petroleum, but considerable asphaltic constituents. The great body of the midcontinental fields yields oils with mixed Constituents; they are usually referred to as oils with a mixed base, paraffin and asphaltic, and the lubricants made Jrom them possess a peculiar composition and quality quite differ- ent from those of the Appalachian or the Southern crudes. From the general composition of these varieties of petroleum,  December, 1923 INDUXTRIAL AND ENGINEERING CHEMISTRY 1235 Fraction c. 120-121 130-131 138-141 160-152 168-170 182-184 194-196 213-214 237-238 244-246 Specific Gravity 0.8600 0.8631 0.8648 0.8692 0.8696 0.8722 0.8730 0.8750 0.8834 0.8840 0.8837 0.8847 TABLE 1-DISTILLABLE C H Mol. Wt. % % --DBTERMINATIONS- 177 190 204 21s 226 244 258 270 334 348 86.61 86.67 86.62 87.10 86.87 87.08 86.95 86.90 86.65 86.73 13.26 13.23 13.33 12.75 12.85 12.82 13.12 12.95 13.24 13.21 Light Hydrocarbc 343 86.62 13.25 389 86.70 13.25 CONSTITUENTS OF MECCA STROLEUM -RBQU_IRSD-- -, Hydrocarbon Mol. Wt. c % 86.66 86.60 86.54 87.28 87.18 87.10 87.03 86.96 86.75 346 86.70 ms rom Mecca Vacuum esidue 180 194 208 220 234 248 262 276 332 n % 13.34 13.40 13.46 12.72 12.82 12.90 12.97 13.04 13.25 13.30 they seemed especially well adapted for this investigation, as representing the principal fields. Mecca petroleum, specific gravity 0.9023, known as a natural lubricant since the beginning of the petroleum indus- try, is typical of occasionally occurring small pockets or sec- tions at shallow depths where the srcinal oil has been par- tially refined by natural agencies, leaving only hydrocarbons with large molecular weights, containing no gasoline, kerosene, or paraffin hydrocarbons and a very small amount of the asphaltic hydrocarbons, All but 12 per cent of the lighter end form the best lubricants. DISTILLABLE ONSTITUENTS F MECCA ETROLEUM On account of its peculiar composition, and since there is an opportunity, for the first time, to give a description of the undecomposed hydrocarbons in a crude oil from beginning to end, it seemed of interest to make the separation of Mecca oil complete from the first distillate. The lower constituents were, therefore, separated by several distillations in VUCUO refined, and the values obtained for specific gravity, molec- ular weight, and percentage composition are given in Table 11. The peculiar disagreeable odor of some of the distillates indicates that the crude oil is not so far removed from its srcinal organic source as the Appalachian oils. These determinations of refractive index increase with increase in specific gravity and in molecular weight the op- posite of the hydrocarbons in the Appalachian oils, and, as will appear later, even in the Mecca hydrocarbons of higher molecular weight in the vacuum residue. The distillate 244 to 246 C., specific gravity 0.8840, treated as in the separation of the D and H series, gave a D hydrocarbon, specific gravity 0.8850, refractive index 1.4865; and an H hy- drocai*bon, specific gravity 0.8835, a lower refractive index, 1.4765, both indicating more than one series, as in the higher hydrocarbons. Some of the Mecca vacuum residue that can be distilled at 300 to 320 O C. without decomposition, and that has been refined for use as a lubricant on fine watch and clock bearings, was separated by the solvent into the following fractions Specific Index of Fraction Gravity Refraction 1-0 0.8837 1.4835 The molecular weight and analysis gave 1-H 0.8780 1.4805 the following formulas for the D group, 2-0 0.8789 1.4815 indicating the series CnHzn-i: 2-H 0.8710 1.4765 CziHaa 3-0 0.8705 1.4815 CZZH403-H 0.8682 1.4755 Ci4H44 4-0 0.8745 1.4785 CzrH4s 4- H 0.8680 1.4760 CisHrx 5 0 0.8750 .... , These hydrocarbons form the connecting link in the series between those that can and those that cannot be distilled. The data of this examination indicate more than one series. S~RIEB KD HOMOLOQ YDROCARBONS N PETROLEUM Investigations carried on in this laboratory and elsewhere have shown that petroleum is chiefly composed in variable proportions of the series CnHzn + f gasoline, kerosene, and ClkH4e 348 86.70 13.30 CzaHrz 388 86.60 13.40 Refractive Series Index CnHzn-2 1.4605 CnHzn- 2 1.4625 CnHzn-2 1,4650 CnHzn-4 1.4665 CnHzn-4 1.4715 CnHan-i 1.4710 CnHPn-4 1.4726 CnHzn-r 1.4750 CnHzn-4 1,4785 CnHzn-4 1.4815 CnHm-r CnHzn-i paraffin hydrocarbons; the series CnHzs - , the light lu- bricants, especially of Appalachian petroleum; the series C.HZn- and CnH2,- 8, the heavier lubricants, the aromatic derivatives of benzene; and heavier series still poorer in hydrogen to CnHPr- 20 t,han appear in this paper are reported as present in European petroleum. The homo- logs of the heavier series above 300 C. vacuo appear to in- crease in regular increments similar to the distillable series- the D hydrocarbons, lubricants to the final heavy ends, except in the asphaltic crudes, and the H hydrocarbons, asphaltic in the heavy ends-in all except the Appalachian petroleum. In the upper ends of the series first separated of all the oils examined, the specific gravity of the fractions increased very materially, some even higher than those of the lower ends. This was found to be caused by carboxylic acids or ethers more soluble than the hydrocarbons themselves. By further treatment of the upper fractions, the soluble oils were re- moved, leaving the hydrocarbons in Table 111. The first ten to fifteen D and H homologs separated in each crude oil were given two or more extractions and collected in the smaller groups presented in this table. Much time was lost in this work before it was learned that the crude oils contained more than one series of lubricants, and that the series as well as the individual homologs differed materially in solubility. While the formulas and series represent the definite compo- sition of the fractions separated, it should require the manip- ulation of much larger quantities of the crude oils thanis possible in the ordinary chemical laboratory, and, as in frac- tional distillation, a greatly prolonged treatment to isolate with closer approximation the individual hydrocarbons. To avoid serious loss in watch-glass transference, the fractions were kept in bottles saturated with the solvent and small lots were dried at 120 O C. for examination. For the purpose of showing at a glance the consistency of the hydrocarbons described in the preceding table as they appear spread out on watch glasses, in Table IV is given a brief description of the first and last members of each series from all the crude oils. In the destructive distillation of Appalachian petroleum by the common method of refining, the most valuable lubri- cants of the heavy ends, such as the last D and H fractions in the Cabin Creek, Rosenbury, and Mecca (Table 111), the best lubricants in any petroleum, are lost in coking. This is of less consequence in the asphaltic oils, for the lubricants in these crudes are for the most part carried over in the steam distillates, leaving only asphaltic residues. On account of the less solubiliky of the lower members of each series and the separation of homologs in only one direc- tion, it was possible to remove very completely the higher homologs, and, therefore, to obtain data for the calculation of the formulas of the lowest residual hydrocarbons as re- liable as the methods of definition are capable of yielding. These last hydrocarbons were, therefore, carefully purified for the comparison of physical properties and lubricant value. Those from the heavier oils have the intensified qualities of the commercial asphalts; black in color, they may be drawn  1236 INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 15, No. 12 TABLE 11 r __ ALCULATED--- FORMULA Mol. Wt. Per cent Per cent H REIIRACTIVB SERIES INDEX Cabin Creek _. DETE_RMINED-----H PECIFIC GRAVITY c Per cent RACTION Mol. Wt. Per cent D Series 1 2 3 0.8755 0.8764 0.8815 0.8882 0.8829 0.8832 0,8835 0.8855 309 327 428 452 488 585 717 803 86.76 86.76 86.56 86.45 86.32 86.35 86.10 86.27 13.21 13.18 13.34 13.44 13.48 13.59 13.79 13.73 12.70 12.64 12.86 13.51 13.22 13.42 13.43 13.40 13.24 13.39 13.71 12.85 13.16 13.25 13.30 13.29 13.37 13.52 13.28 13.35 12.61 12.70 13.10 13.20 13.22 13.50 13.47 13.42 12.37 12.48 12.82 12.76 12.73 12.75 12.56 11.91 11.81 12.15 12.30 13.32 13.18 12.05 12.45 12.35 12.25 12 25 12.24 12.35 12.27 12.53 11.93 12.53 13.03 12.68 11.96 12.01 12.53 12.60 12.66 13.21 13.30 12.68 C22H4O 304 86.84 13.16 CnHzn-4 1.4920 C24H44 332 86.75 13.25 CnHzn-4 .... CaiHss 430 86.50 13.50 CnHzn-4 .... C83H62 458 86.46 13.54 CnHan-4 .... CssHe6 486 86.42 13.58 CnHzn-4 .... CaHso 584 86.30 13.70 CnHzn-4 .... CszHioo 724 86.20 13.80 CnHzn-4 1.4880 CS3H112 808 86.14 13.86 CnHzn-4 1.4810 CaaHsa 454 87.22 12.78 CnHzn- 1.4880 CS4H60 468 87.20 12.80 CnHzn- I .... C36H64 496 87.10 12.90 CnHzn-a .... C46H8P 636 86.79 13.21 CnHzn- 8 .... CasHioa 762 86.60 13.40 CnHzn- s .... 4H100 748 86.64 13.36 CnHzn- 1.4870 CizzHzsa 1700 86.32 13.68 CnHzn-la 1.4810 4 5 6 7 8 eries 1 2 3 0.8721 0.8725 0.8729 0,8819 0.8863 0,8873 0,9063 459 476 490 635 87.21 87.20 87.02 86.52 86.72 86.72 86.50 4 5 6 7 D Series 760 769 1696 Rosenbury 0.8796 0.8816 0.8822 0.8836 384 438 481 518 86.13 86.68 86.42 86.15 CzaHsn 388 86.60 13.40 CnHzn- a 1.4930 C8ZH60 444 86.48 13.52 CnHzn- 1.4890 Cs7H7o 514 86.38 13.62 CnHzn- 1.4880 C3SH66 486 86.42 13.58 CnHnn- 8 2 3 4 Series 1 2 3 4 5 6 7 8 9 0.8742 0.876.5 0.8812 0,8850 0.8848 0.8865 0.8950 0,8998 0.9079 549 87.08 86.78 86.65 86.60 86.59 86.63 86.49 86.69 86.58 552 622 636 664 720 804 832 954 1734 86.96 86.82 86.78 86.74 86.68 86.56 86.54 86.80 86.50 13.04 13,18 13.22 13.26 13.32 13.44 13 46 13.20 13.50 CnHzn-a CnHzn- s CnHzn- CnHzn-a CnHzn- s CnHzn- s CnHzn- CnHzn-iz nHzn- 16 1.4920 .... .... .... .... 1.4870 1.4870 .... .... 6i5 639 666 727 805 830 980 1730 Mecca D Series 1 2 3 4 5 6 7 8 H eries 1 2 3 0.8945 0.8950 0.8960 0.8962 0,8966 0.8982 0,. 8998 0.9171 465 500 631 662 728 770 832 1080 87.37 87.13 86.87 86.60 86.62 86.41 86.45 86.68 468 496 636 664 734 776 832 1084 87.20 87.10 86.78 86.75 86.66 86.60 86.54 86.34 12.80 12.90 13.22 13.25 13.34 13.40 13.46 13.66 CnHm- 8 CnHzn- CnHzn- 8 CnHzn- s CnHzn- s CnHzn-s CnHzn- a CnHzn- CnHzn-12 CnHzn-iz CnHzn-iz CnHzn-a CnHzn- 12 CnHzn-la CnHzn-zo .... .... .... .... .... .... .... .... .... .... .... .... .... 0.9058 0.9072 0.9018 0 9022 0.9052 0.9065 0.9600 477 550 684 725 823 992 1662 87.65 87,57 87.06 87.16 87.12 87.22 87.34 478 548 688 688 828 992 1668 87.87 87.59 87.21 87.16 86.96 87.10 87.23 12.13 12.41 12.79 12.76 13.04 12.90 12.77 4 5 6 7 Sour Lake, Texas 0.9408 0.9467 0.9482 0.9535 0.9595 0.9643 450 462 503 531 554 849 87.93 88,09 87.82 87.58 87.62 86.80 450 464 506 534 562 856 88.00 87.93 87.74 87.64 87.54 86.92 12.08 12.07 12.26 12.36 12.46 13.08 CnHzn- 12 CnHzn-in CnHm-la CnHzn-ia CnHzn-12 CnHm-iz CnHzn-is CnHan-16 CnHzn-16 CnHan-1s CnHzn-zo CnHzn-zo CnHzn-no CnHan-80 1.4980 .... 1.4960 1.4940 1.4970 .... 600 632 684 712 785 848 988 1240 88.12 87.62 87.72 87.64 87.88 87.74 87.45 87.98 12.00 12.38 12.28 12.36 12.12 12.26 12.55 12.02 0.9470 0.9497 0.9559 0.9643 0.9700 0.9714 0.9720 1.0230 602 630 680 716 792 854 98 1239 87.90 87.60 87.55 87.58 87.66 87.50 87.65 87.60 .... 1,4940 .... .... Baku, Russia D Series 308 88.05 11.95 CnHzn-lo 1.4920 396 87.88 12.12 CnHzn-io 494 87.47 12.53 CnHzn-io .... 634 87.06 12.94 CnHzn-io .... 1026 86.55 13.45 CnHzn-io .... 0,9186 0.9251 0,9254 0.9262 0.9288 381 402 494 640 1022 300 334 378 420 460 661 847 1098 87.42 87.75 87.46 86.91 87.29 1 2 3 4 5 H Series 1 2 3 4 5 6 7 8 0.9025 0.9160 0.9167 0.9150 0.9162 0,9242 0.9360 0.9402 87.95 87.98 87.36 87.28 87.29 86.72 86.63 98.31 300 88.00 12.00 CnHzn- s ,... 328 87.80 12.20 CnHzn-a .. 384 87.50 12.50 CnHzn- s .... 426 87.32 12.68 CnHzn- .... 454 87.22 12.78 CnHzn- s .... 664 86.75 13.25 CnHzn- s .... 846 86.52 13.48 CnHzn- 8 .... 1100 87.28 12,72 CnHm-zo 1,4910 out to a considerable length in very fine threads, and possess great adhesiveness. The residual lubricants from the Ap- palachian crudes, amber in color, greasy in feel, and of high viscosity, differ in appearance from the gray basic stocks of the midcontinental lubricants, which are doubtless to some extent mixtures with asphaltic bases. On account of the limits of accuracy in the determinations of molecular weights mentioned above, the fractions with higher values, such as the Rosenbury fraction CI25H2 4, may be incorrect by one or more increments CH2, but by the de- terminations upon which it is based it must have a high value, for the fraction 9-H, specific gravity 0.8933, gave in two molecular weight determinations (1) 1722, (2) 1718; further fractioned with specific gravity 0.8943 it gave 1728; and still further fractioned with specific gravity 0.9079 it gave 1730. There appears, therefore, to be no doubt as to its high molec- ular composition. So dso the molecular weight 1696 of the Cabin Creek 7-27 fraction, specific gravity 0.9063, with the next largest value, appears to be correct, since it was separated from both specimens of the crude oil which gave fractions with the molecular weights (1) 1685, (2) 1690, and with analysis corresponding to the formula C123H232 There- fore, with methane as the first gaseous hydrocarbon and pentane as the first liquid, under ordinary pressure, passing
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