ANALYTICAL
EDITION
Industrial VOLUME 6 NUMBER6
AND E N G I N E E R I N G
NOVEMBER 15,
Chemistry
1934
PUBLISHED BY THE AMERICAN CHEMICAL SOCIETY HARRISON E. HOWE,EDITOR
A. Method for Evaluating the ViscosityTemperature Characteristics of Oils W. B. MCCLUERAND M. R. FENSKE Petroleum Refining Laboratory, Pennsylvania State College, State College, Pa. ITH the development of new refining processes by means of which the viscosity-temperature characteristics Of Oils may be varied appreciably, the problem of evaluating the viscosity characteristics of different lubricants over a wide range in temperature becomes increasingly important. This is especially true of automotive lubricants, because the mechanical parts must be lubricated satisfactorily both a t relatively low temperatures and a t the relatively high temperatures encountered in severe operating conditions. A satisfactorv motor lubricant must serve a t least two uurposes: (I) the lubricant must be sufficiently fluid at-low temperatures so that the car can be started readily and the various parts may receive oil during starting; (2) the lubricant must be sufficiently viscous a t higher temperatures so that the parts of the motor may not suffer undue wear during long periods of operation a t engine temperatures. For these reasons, it is generally recognized that a lubricant whose viscosity changes slowly with temperature is more satisfactory under severe operating conditions than another lubricant whose viscosity changes rapidly with temperature. The fact that an oil must be relatively viscous a t higher temperatures is readily apparent since many of the parts to be lubricated operate a t elevated temperatures. It may not be so obvious that an oil must be relatively fluid a t low temperatures. Larson (9), Becker ( I ) , and Blackwood and Rickles (3) have shown that the power required to start a car in cold weather is directly related to the viscosity of the crankcase lubricant a t the starting temperatures. Lederer and Zublin (11) have shown that the pumpability of an oil a t low temperatures is dependent in a large measure on the viscosity of the oil a t operating temperatures and to a lesser degree on the pour point of the oil. For these reasons, it is desirable that the rate of change of viscosity with temperature for the crankcase lubricant be as low as possible. Various means for evaluating and comparing oils with respect to their relative rates of change of viscosity with temperature are available. These may be listed as follows: I. Ratio of the 100" F. (37.8' C.) viscosity to the 210' F. (98.9' c.)viscosity. 2. Viscosity index as developed by Dean and Davis (7) and Mer revised by Davis, Lapeyrouse, and Dean (6). 3. Viscosity slope number developed by Bell and Sharp (g)
W
by means of arbitrary arithmetical scales superimposed on the
A. S. T. M. viscosity-temperature chart, D-341-32-T.
4. Viscosity gradient devised by Clayden (4) for expressing the viscosity temperature slope of oils by means of angles and fundamental viscosity units. 5 . Viscosity-gravity constant introduced by Hill and Coates (8) in 1928 as a means for evaluating the paraffinicity or naphthenicity Of Oil'* 6. Viscosity gravity zones recommended by Larson and Schwaderer (10) in 1932 and 1933 as a means for graphical esti-
mation of relative viscosity-temperature characteristics. 7. Gravity index (11)based on an empirical relation between viscosity-gravity constant and viscosity index.
Each of these several methods for comparing lubricating oils with respect to their viscosity-temperature characteristics may be divided roughly into two classes, depending upon whether they are based directly upon viscosity-temperature charts or upon a comparison with certain specific types of oil. Each method of classifying oils appears to have certain fairly well defined advantages and disadvantages, but there is no apparent means by which the advantages of each classification may be retained. None of the methods result in a quantitative expression of the actual viscosity a t low or high temperatures. Therefore, for the purpose of obtaining further means of comparing oils in this respect it has appeared desirable to start with an entirely different reference basis. The purpose of this paper is to outline a method by means of which the viscosities of different oils may be compared quantitatively, either at the low temperatures encountered in winter starting or a t the high temperatures encountered during motor operation. With the present lack of information on the materials which compose petroleum, it appears practically impossible to develop a method for evaluating this characteristic of lubricating oils on an absolute basis. For this reason, practically any method devised at the present time for this purpose must be established on a relative and comparative basis. From the point of view of comparing the performance of lubricants in service in so far as this is dependent upon viscosity, it seems logical to evaluate oils a t two temperature extremes, one high and one low. Also, .practical engineering usefulness dictates that fundamental units such as the stoke or poise be used instead of arbitrary units of viscosity such as Saybolt seconds.
389
ANALYTICAL EDITION
390
Vol. 6 , No. 6
TARLEI. VISCOSITY-TEMPERATURE RELATIONS OF OILS KINEMATIC VISCOSITY(CENTISTOKES) KINEMATIC VISCOSITY (CENTISTOKES) KINEMATIC ' VISCOSITY (CENTISTOKES) 210," 400' 210," 400' 2lOC0 400° ZERO F. F.d VISF. F.d VISF. F.d VISVISCOSI~ 'Y 0' F.a 100' F.b (98.9'(204.4' COSITY 0' F.' 100" F.b(98.9°(204.40 COSITY O o F.a 100' F.6 (98.9" (204.4O COSITY FACTOR (-17.8'C.) (37.8OC.1 C.) C.) INDEX (-17.8°C.)(37.80 C.) C.) C.) INDEX ( -17.8' C .) (37.8' C.) C.) C.) INDEX 0.1 143.1 17.12 6 . 0 1.62 187 329.2 28.29 7 . 0 2.01 170 787. 1 48.12 10.0 2.52 155 0.2 286.2 21.70 5.0 1.53 158 658.4 34.23 7 . 0 1.80 153 1,574 58.14 10.0 2.28 141 572.4 0.4 24.80 5 . 0 1.32 139 1,317 40.92 7.0 1.65 133 3,148 69.35 10.0 2.09 126 27.45 5 . 0 1.25 122 0.6 858.6 1,975 45.34 7 . 0 1.57 119 4,723 77.31 10.0 1.99 115 1,145 29.40 5.0 1.21 109 0.8 2,634 48.50 7 . 0 1.52 110 82.78 10.0 1.93 6,297 108 1,431 30.90 5.0 1.19 99 1.0 3,292 51.21 7 . 0 1.49 101 7,871 87.50 10.0 1.88 101 2,862 36.10 5.0 1.11 65 6,584 2.0 60.02 7 . 0 1.39 74 15,742 102.7 10.0 1.75 81 5,724 42.04 5 . 0 1.04 25 13,170 4.0 69.94 7 . 0 1.30 44 31,484 121.0 10.0 1.65 56 -1 6.0 8,586 45.89 5 . 0 1.01 19,750 76.51 7 . 0 1.26 24 47,226 132.0 10.0 1.60 41 11,450 48.44 5.0 0.99 -18 26,340 80.95 7 . 0 1.23 10 8.0 62,968 141.1 10.0 1.55 28 14,310 -34 50.87 5 . 0 0.97 10.0 32,920 86.12 7 . 0 1.21 -6 78,710 148.2 10.0 1.53 18 -84 28,620 58.13 5 . 0 0.92 65,840 20.0 99.50 7 . 0 1.15 -47 157,420 169.5 10.0 1.46 -11 131,700 57,240 68.71 5 . 0 0.89 -155 112.0 40.0 7 . 0 1.10 -86 314,840 195.8 10.0 1.37 -48 85,860 71.18 5 . 0 0.86 -172 197,500 60.0 120.6 7 . 0 1.08 -113 472,260 210.4 10.0 1.35 -68 114,380 75.19 5 . 0 0.85 -198 263,400 80.0 127.6 7 . 0 1.06 -135 629 680 224.5 10.0 1.33 -87 78.20 5 . 0 0.84 -219 329,200 100.0 143,100 132.6 7 . 0 1.05 -151 787,'lOO 233.7 10.0 1.31 -100 2,080 146 4,109 134.9 20.0 3.93 0.1 87.78 15.0 3.27 138 10,590 246.1 30.0 5.08 131 15.0 2.96 4,160 135 8,217 106.3 163.1 20.0 3.56 0.2 128 21,180 297.9 30.0 4.61 123 122 16,434 127.6 15.0 2.71 196.1 20.0 3.26 8,320 0.4 117 42,360 358.6 30.0 4.22 114 113 142.2 15.0 2.59 24,652 218.5 20.0 3.12 12,481 110 0.6 63,540 400.1 30.0 4.03 108 152.0 15.0 2.51 107 32,869 234.1 20.0 3.02 16,641 105 0.8 84,720 429.5 30.0 3.90 104 160.9 15.0 2.45 101 41,086 247.8 20.0 2.95 20,801 100 1.0 105,900 455.6 30.0 3.85 100 15.0 2.31 84 82,172 189.4 292.9 20.0 2.75 41,602 85 2.0 211 800 540.1 30.0 3.55 88 73 164340 222.5 15.0 2.15 344.8 20.0 2.58 68 83,204 4.0 423:600 638.4 30.0 3.33 74 244.0 15.0 2.07 51 246:520 380.3 124,806 20.0 2.49 56 6.0 635,400 30.0 3.21 705.0 64 15.0 2.03 41 328690 261.1 404.3 20.0 2.43 48 847 200 166,408 8.0 30.0 3.13 752.7 57 33 410:860 208,010 273.6 15.0 1.99 426.8 41 20.0 2.39 10.0 1,059:OOO 51 793.9 30.0 3.08 5 821,720 318.2 15.0 1.89 495.9 20.0 2.27 17 416,020 20.0 30.0 2.91 2,118,000 926.7 32 15.0 1.80 -26 1,643,440 832 040 368.0 575.0 20.0 2.16 40.0 -9 4 236 000 1080 9 30.0 2.77 1,248:060 400.2 15.0 1.76 -45 2465160 626.1 20.0 2.09 -26 6,'354,'000 60.0 30.0 2.69 1176 -6 -59 3'286'880 423.6 15.0 1.72 665.7 20.0 2.05 1,664,080 80.0 -40 8,472,000 30.0 2.64 1250 -17 443.0 15.0 1.70 -71 4:108:600 697.4 20.0 2.03 -29 2,080,100 -50 1311 10,590,000 100.0 30.0 2.59 40.0 6.08 127 20,701 377.4 0.1 40.0 5.11 120 41,402 457.0 0.2 113 40.0 5.07 548.9 82,804 0.4 107 615.8 40.0 4.83 a For oils having a zero viscosity factor of 1 the viscosity a t Bo F. -17 8 O C ) was calcu124,206 0.6 104 40.0 4.67 661.1 165,608 0.8 lated from the 100" F. (37.8' C.) and 210' F. ($8.9' C.)viscosities by Aquation 2: All other 100 40.0 4.66 viscosities a t 0' F.-are definite percentage amounts, de ending .upon the numericd value 207,010 702.0 1.0 of the zero viscosit factor of the Oo F. viscosity of the regrence oil. 90 414,020 833.5 40.0 4.25 2.0 For oils whicx have a aero viscosity factor of 1, the 100' F. viscosity was calculated 77 40.0 3.97 987.8 4.0 828 040 69 1093 40.0 3.84 6.0 1,242:060 from the 210" F. viscosity by Equation 1. All other viscosities at looo F. were calculated b means of Equation 2, since the viscosities of these various oils were known a t temperatures 40.0 3.74 1166 63 1,656,080 8.0 of210° and-no R. . 1233 40.0 3.67 . _ 57 10.0 2,070,100 Viscosity a t 210' F., at which temperature all oils which are t o be rated in terms of 1438 4,140,200 40.0 3.47 40 20.0 viscosity ratio a t 0' F. have equal yiscosity. 40.0 3.29 1686 19 8,280,400 40.0 d Viscosity calculated by Equation 2. 40.0 3.20 6 1844 12 420 600 60.0 40.0 3.14 -4 1963 l6:560:800 80.0 40.0 3.08 -12 2058 20,701,000 100.0
*
PROPOSED METHOD The proposed method for comparing the viscosity-temperature characteristics of lubricating oils is largely mathemetical in nature and depends on relatively simple procedures and concepts. The steps may be outlined as follows: 1. A single type of oil is used for reference purposes. 2. Com arisons are made with oils having equal viscosities at 210' F. h8.9' C.) 3. The 100" F. i37.8' C.) viscosity of the reference oil is expressed in terms of its 210' F. (98.9' C.) viscosity by a simple equation. 4. The viscosity of the reference oil can be calculated at any other temperature by known relations. 5. All oils, if matched as to viscosity at 210' F. (98.9' C.), have a definite viscosity ratio at 0' F. (-17.8' C.) with respect to the reference oil. 6. The 100' F. (37.8' C.) viscosity of any oil havin known viscosities at 0' F. (-17.8' C.) and 210" F. (98.9' C.y can be calculated. 7. The mathematical results can be expressed accurately by means of a simple nomograph.
The 100" F. (37.8' C.) viscosities, Y , of the reference oils were calculated for given viscosities at 210" F. (98.9' C.), X , by means of the following equation, log,, Y = 1.502 log,, X 0.4400 (1)
+
This equation may be considered as defining the viscosity characteristics of hypothetical oils for the purpose of establishing a reference standard, or it may be considered as defining the viscosity characteristics of actual oils, since for all practical purposes the equation satisfactorily correlates the viscosity-temperature characteristics of oils refined from an extreme type of paraffin-base crude oil. When the viscosities of a lubricating oil are known a t two
temperatures, the viscosity a t a third temDerature can be calculated by well-known relations. Two equations which are probably better known than others are Cragoe's (5) and the one employed by the American Society for Testing Materials for developing the viscosity-temperature chart designated as D-341-32-T. These two equations result in approximately similar results, but the calculations in this paper are based on the A. S. T. M. equation, which is probably more widely known and used than Cragoe's equation. The A. S. T. M. equation (IS) is: log log (KV
+ 0.8) = A log T + B
(2)
where KV is kinematic viscosity in centistokes, T is absolute temperature, and A and B are constants. Use of this equation instead of the A.S.T.M. viscosity-temperature chart is desirable, because the errors inherent in graphical extrapolation and interpolation are eliminated. The results presented in this paper are based on Equations 1 and 2, plus the concept that oils matched as to viscosity at 210' F. (98.9' C.) have different viscosities a t 0' F. (-17.8" C.) depending upon their viscosity-temperature characteristics, and that the latter may be expressed as the ratio of the 0' F. (-17.8' C.) viscosity of any given oil and the 0' F. (-17.8" C.) viscosity of a reference oil. For conciseness, this viscosity ratio at 0' F. (- 17.8" C.) has been termed the "zero viscosity factor." The numerical value of this factor is a quantitative measure of the 0' F. (-17.8' C.) viscosity of an oil, since the product of the 0' F. (-17.8' C.) viscosity of the reference oil and the determined zero viscosity factor is the 0' F. (- 17.8" C.) viscosity of that oil. AI1 viscosities are expressed in terms of kinematic viscosity (centistokes), in order that fundamental units may be used.
November 15,1934
I N DUSTR IA L A N D EN G I NEER I N G CHE M I STR Y
By choosing any given viscosity a t 210' F. (98.9' C.) for the reference oil, and by assigning a definite value for the viscosity ratio a t 0' F. (-17.8' C.), it is possible to calculate the 0' F. (-17.8' C.) and 100' F. (37.8' C.) viscosities of oils having the assumed viscosity characteristics. I
1
391
the viscosity a t 210' F. (98.9" C.) and 100" F. (37.8' C.). The chart is used by connecting the points representing the viscosities of an oil a t 210' F. (98.9' C.) and 100" F. (37.8' C.) with a straight edge and reading off the value of the zero viscosity factor a t the point where the straight edge intersects the sloping line on the right-hand side of the chart. The three scales shown are logarithmic and interpolations should be made with this in mind. The data contained in Table I indicate further that the viscosity index of oils is not an absolute criterion of relative viscosities a t low temperatures. For example, oils which are 10 times more viscous than the standard reference oils a t 0' F. (-17.8' C.) and have 210" F. (98.9' C.) viscosities of 5.0, 15, and 30 centistokes require viscosity indexes of -34, +30, and +51, respectively. These variations in viscosity index are probably greater than would be anticipated for oils having a constant viscosity ratio a t 0' F. (-17.8' C.). It is indicated therefore that viscosity index alone is not sufficient for accurately evaluating the 0' F. (-17.8' C.) viscosity characteristics of oils. Oils having a zero viscosity factor of 1.0 have viscosity index values of approximately 100 through a range in viscosity a t 210' F. (98.9' C.) of 5.0 to 40 centistokes. The relation between viscosity index, 210' F. (98.9' C.) viscosity, and zero viscosity factor of oils is reversed when oils have zero viscosity factors less than 1.0. For example, oils having a zero viscosity factor of 0.1 and 210' F. (98.9' C.) viscosities of 5.0, 15, and 30 centistokes have viscosity indexes of 187, 143, and 131, respectively. Significant differences in viscosity index are therefore less important in the case of light oils than in the case of relatively heavy oils.
FIGURE 1. GRAPHICAL REPRESENTATION OF METHOD USED IN DEVELOPING ZERO VISCOSITY FACTOR
The method followed in establishing the zero viscosity factorpathematically is indicated graphically by Figure 1. The viscosity-temperature characteristics of four oils are represented, two oils having 210' F. (98.9' C.) viscosities of 5 centistokes and the remaining two oils having 210' F. (98.9' C.) viscosities of 30 centistokes. The 100' F. (37.8' C.) viscosities of the light and heavy reference oils designated by points B and G, respectively, were obtained from the 210' F. (98.9' C.) viscosities of 5 and 30 centistokes respectively, by means of Equation 1. The 0' F. (-17.8' d.) viscosity of the light and heavy reference oils were obtained from their res ctive viscosities at 100" F. (37.8' C.) and 210' F. (98.9' C . G y solving Equation 2. The 0' F. (-17.8' C.) viscosity of oil 1 was obtained by multiplying the 0' F. (-17.8' C.) viscosity of the light reference oil by a zero viscosity factor of 10 and its 100' F. (37.8' C.) viscosity was obtained by substituting viscosities at 0' F. (- 17.8' C.) and 210' F. (98.9' C.) in E uation 2. Oil 2 is matched as to viscosity at 210' F. 798.9' C.) with a reference oil having a viscosity at 210' F. (98.9' C.) of 30 centistokes. By assuming a zero viscosity factor of 5 for oil 2, it is possihle to calculate the viscosities of oil 2 at temperatures of 100' F. (37.8' C.) and 0' F. (-17.8' C.). Having established the 100' F. (37.8' C.) and 210' F. (98.9' C.) viscosities of oils in this manner, it, is possible to calculate the viscosity index of oils having definite zero viscosity factors. Also the viscosity of oils having definite viscosity relations at 0' F. (-17.8' C.) may be calculated at any desired temperature (say, 400" F.) by solving Equation 2. The viscosity-temperature characteristics of a large number of oils having different210' F. (98.9' C.) viscosities and different zero viscosity factors have been calculated by the method indicated above. Calculated data for oils having viscosities at 210" F. (98.9' C.) from 5.0 centistokes (a light oil) to 40.0 centistokes (an extremely heavy oil) and having zero viscosity factors from 0.1 to 100 are contained in Table I. The data contained in Table I have been used as a basis for constructing a nomograph (Figure 2) by means of which the zero viscosity factor of oils may be determined readily from
Variations in viscosity index such as those indicated above are not unusual when the viscosity index concept is applied to theoretical considerations. If the ideal lubricant is defined as an oil whose viscosity does not change with temperature, it is possible to calculate the maximum theoretical viscosity index for such oils having different viscosities at 210 F. (98.9' C.). When these calculations are made, it is found
-
ANALYTICAL EDITION
392
that the viscosity indexes would be approximately 250 for a light oil, and 200 and 160 for medium and heavy oils, respectively. In other words, the maximum theoretical viscosity index of hypothetical lubricants decreases rapidly with increasing viscosity at 210' F. (98.9' C.). This effect is indicated in Figure 3 for oils having extremely low zero viscosity factors.
Vol. 6 , No. 6
data on reference oils contained in Table I1 or by use of the nomograph and Equations 3 or 4. The viscosity of oils a t a temperature of 400" F. (204.4" C.) can be estimated fairly closely by the use of the zero viscosity factor and the data contained in Table I. For example, if an oil were found to have a zero viscosity factor of 5 and were known to have a 210" F. (98.9" C.) viscosity of 15.0 centistokes, the data contained in Table I indicate that this oil would have a viscosity a t 400" F. (204.4" C.) of approximately 2.1 centistokes. It is also possible to obtain the 400" F. (204.4 C.) viscosity of oils having 210" F. (98.9" C . ) viscosities other than those listed in Table I by interpolation between the tabulated values. It is further possible that a nomograph based on the zero viscosity factor, viscosity at 210" F. (98.9" C.), and viscosity a t 400" F. (204.4" C.) might be developed. TABLE 11. VISCOSITY-TEMPERATURE RELATIONS OF REFERENCE OILS
210' F. 5 6 7 8 9 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 0
-100
-M
0
50
100
150
2(
Viscosity I&
FIGURE 3. RELATION BETWEEN VISCOSlTY I N D E X ZERO VISCOSITY FACTOR
AND
It is evident that the zero viscosity factor offers a ready means for approximating closely the 0" F. (-17.8" C.) viscosities of oils without resorting to an A. S. T. M. viscositytemperature chart, provided a ready means for obtaining the 0" F. (- 17.8" C.) viscosity of the reference oils is available. Fortunately, relatively simple means exist by which the 0" F. (-17.8" C.) viscosity of reference oils may be calculated. This equation is loglo 2 = 2.383 lOg,,X
+ 1.5046
(3)
where 2 is the viscosity in centistokes a t 0' F. (-17.8" C.) and X is the viscosity in centistokes a t 210" F. (98.9' C.). Also, the 0" F. (-17.8' C.) viscosity of reference oils can be calculated from the 100" F. (37.8' C.) viscosity by the equation loglo 2
=
1.586 loglo Y
+ 0.8065
(4)
where 2 and Y are the viscosities in centistokes a t 0" F. (-17.8' C.) and 100' F. (37.8' C.), respectively. Table I1 contains data relating to the 0' F. ( - 17.8" C.) viscosity of reference oils for viscosities varying from 5.0 to 40 centistokes a t 210' F. (98.9' C.). The data in column A were obtained by applying successively Equations 1 and 2, while the data in columns B and C were obtained from Equations 3 and 4, respectively. The results in columns B and C do not vary by more than approximately 3 per cent from the results in column A . It follows therefore that the viscosity of an oil a t 0" F. (-17.8" C . ) may be approximated readily by use of the nomograph contained in Figure 2 and the viscosity
KINEMATIC VIaCOSITY (CINTIBTOKIS) 7 0' F. 100' F. A B 30.90 1,431 2,235 40.62 51.21 3,292 62.58 4,561 74.69 6,083 87.50 7,871 12,203 115.1 17 595 145.0 24:154 177.2 31,996 211.6 41,086 247.8 51,207 285.9 62,901 326.9 75,876 367.6 90,247 410.9 455.6 105 900 502.0 123:130 549.9 141 960 599.2 162:OlO 649.9 183,760 702.0 207,010
C
Viscosity ratios a t 400" F. (204.4" C.) for oils matched as to viscosity a t 0" F. (-17.8" C.) might also be developed in a manner similar to that used in establishing the zero viscosity factor. It appears that such a relation would be valuable in further establishing the viscosity-temperature characteristics of lubricating oils through relatively simple and useful means. ACKNOWLEDGMENT The authors are indebted to M. R. Cannon for making the majority of the calculations. LITERATURE CITED (1) Becker, A. E . , Automotive Ind., 64,401 (1931). (2) Bell, T.G.,and Sharp, L. H., Oil Gas J . , 32, No.'13, 13 (1933). (3) Blackwood, A. J., and Rickles, N. H., S. A . E. Journal, 28, 236 (1931). (4) Clayden, A. L., Nat. Petroleum News, 25, No.42,27 (1933). (5) Cragoe, C. S.,World Petroleum Congr. London, Prac., 2, 529 (1934). (6) Davis, G.H. B., Lapeyrouse, M., a n d Dean, E. W., Oil Gas J . , 30, No. 42,92 (1932). (7) Dean, E . W., and Davis, G. H. B., Chem. & Met. Eng., 36, 618 (1929). (8) Hill, J. B., and Coates, H. B., I N D .ENG.CHEY.,20,641 (1928). (9) Larson, C. M., S. A . E. Journal, 29, 211 (1931). (10) Larson, C. M . , and Schwaderer, W. C., Nat. Petroleum News, 24, No. 2,26 (1932); 25, No. 9,25 (1933). (11) Lederer, E . R., and Zublin, E. W., paper presented before American Society of Mechanical Engineers, M a y 22, 1931, S t a t e College, Pa.
(12) McCluer, W.B.,a n d Fenske, M. R., IXD. ENG.CHEM.,24,1371 (1932). (13) Walther, C.,World Petroleum Congr. London, Proc., 2, 419 (1934). RECEIVEDAugust 7, 1934. Presented before the Division of Petroleum Chemistry at the 88th Meeting of the American Chemical Society, Cleveland, Ohio, September 10 t o 14, 1934.
