VISCOSITY OF PINE GUM W. J. RUNCKEL AND I. E. KNAPP Naval Stores Research Division, of Agriculture, New Orleans, La.
U. S . Department
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OR several years the Naval Stores Research Division has advocated cleaning prior to distillation of crude oleoresin or pine gum. In the cleaning process recommended (5) and now in commercial use, the crude gum is diluted. with turpentine, filtered, and washed with water. In designing the equipment required in this process there has been a demand for data on the viscosity of pine gums a t various dilutions and over a range of temperatures. The object of the present investigation was t o determine these data. The crude pine gums used were fresh samples, collected in the Osceola National Forest near Olustee, Fla., of three varietiesslash gum (Pinus caribaea), longleaf gum (Pinus palustris), and longleaf scrape. "Scrape", the crystalline, almost solid material that accumulates on the scarred faces of longleaf pines in the late summer and fall, is troublesome to handle in the processing plants. Such foreign materials as bark, chips, and pine needles were removed from the samples by first warming the gum on a steam bath and then straining through cheesecloth on a steam-heated funnel with slight suction. The turpentine content of the strained gum was determined by steam distillation of a 400-gram sample a t 160" C. t o the point where 10 ml. of distillate contain less than 1.0 ml. of turpentine (4). The moisture was determined by A.S.T.M. method D95-40 (1). Analyses of the crude gums follow : Sample Longleaf gum I,gfl;;2crape
Turpentine, % by Wt. 20.4 17.8 21.6
Moisture, % 4.2 0.4 1.8
Figure 1. -Stormer Viscometer and Auxiliary Equipment
against standard viscosity oils obtained from the Kational Bureau of Standards by the calibration method of Higgins and Pitman (3). Figure 1 shows the assembled equipment. The bath surrounding the sample cup was heated with a 250-watt infrared drying bulb. Graff (9) showed that precise temperature control of small baths is obtainable by using an infrared lamp controlled by a variable-voltage transformer. The lamp was enclosed in a case and the heat was reflected t o the bottom of the bath by a stainless steel mirror. The bath was fitted with an air bubbler t o maintain uniform temperatures in the surrounding oil: To reduce evaporation of the turpentine to a minimum, a steel cover plate, with holes of suitable size for the thermometer, bubbler tube, and rotating shaft, was fitted over the cup and bath.
Grade of Rosin Produced ' M M X
Samples of these crude gums were diluted with freshly distilled gum turpentine (density, 0.8605 a t 26.8" C.) to concentrations of 25, 30, 35, and 40% turpentine by weight. Viscosities were determined in a Stormer viscometer which had been calibrated
TEMPERATURE IN DEGREES C.
Figure 2.
Viscosities of Longleaf Pine Gum (left), Longleaf Pine Scrape (center), and Slash Pine Gum (right)
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INDUSTRIAL AND ENGINEERING CHEMISTRY
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The viscometer cup was filled with the same volume of sample for each series of determinations. The time required for 100 revolutions of the paddle was determined nit11 a stop watch. From the time in seconds, the viscosity in centipoises \-cas calculated, using the constants determined for this particular Stormer viscometer. A typical series of observations and calculated viscosities follows for a longleaf pine gum analyzing 20.47, turpentine and 4.27, water: Temp O
c.”
60.0 62.2 65.0 66.567.0 69.2-69,s 73.0-72.2 75.5 77.0 79.0
Time, t , for 100 Revolutions, Seconds 273.2 209.9 162 7 134.7 107.7 84.1
Calcd. Viscosity, (3.55f) - 1 i , 5 i ,
7 =
Centipoises 952 727 560 460 359 281 205 181 156
62.8 56.0 49.0
Similar data were obtained on the other samples of pine gum a t various dilutions with turpentine. These data are plotted in Figure 2. The percentage figures on each curve indicate the con-
Vol. 38, No. 5
centration of turpentine by n-eight. Viscosity measurements made as the temperature increased, and also as it d e c r c a d , revealed no significant diffcrences. ACKhOWLEDGMENT
The authors n-ish to express their appreciation t o S . C. X c Conncll of the A-aval Stores Station at Olustee, Fla., foi the gum samples; and to F. C. Magne of the Analytical, Physical Cliemical, and Physical Division of the Southern Regional Rcwarch Laboratory for the calibration of the viscometer. LITERATURE CITED
(1) Am. SOC.f o r Testing Materials, Standards, P u t 111, p. 293 (1944).
( 2 ) Graff, M.M., IND. ESG.CHEST., AN.IL. ED.,15, 63s (1943). (3) Higgins, E.F., and Pitman, E.C., J. IND. ENG.CHEX., 12, 587 (1920). ( 4 ) Naval Stores Research Div., unpublished method. ( 5 ) Smith, W. C., Reed, J. O., Veitch, F. P., and Sliingler, G. P., C , S.P a t e n t 2,254,785 (Sept. 2, 1941).
Active Amyl- Isoamyl Alcohol Svstem J
J
E. R. H-AFSLUND
Joseph E . Seagram 61: S o n s , I n c . , Lotciscille, K y .
VAPOR-LIQUID EQUILIBRIUM AT 760 MM. PRESSURE T h e vapor-liquid equilibrium of the active amyl alcoholisoamyl alcohol system was determined at 760 mm. pressure. The active amyl alcohol, 99.34 mole %, was obtained by repeated fractionations in two Lecky-Ewe11 columns. The jacketed Othmer still used in the study w-as “standardized” on the ethyl alcohol-water system and gave results comparable to reliable literature data. It is shown statistically that the relative volatility and concentration of the two amyl alcohols may be considered independent, and that the best estimate of the relative volatility is 1.0792.
T
HE two main components of fusel oils are active amy1 alcohol (I-rotatory 2-methyl-1-butanol) and isoamyl alcohol (3methyl-1-butanol). Isoamyl alcohol is easily obtained in a pure state from other sources, but active amyl alcohol usually has been obtained from fusel oil. Separation of the two alcohols is difficult by chemical means (16) and results in low yields. Recently fractional distillation in high-efficiency columns has been used to separate the two alcohols ( I S , 1 7 ) . The purpose of this paper is to present vapor-liquid equilibrium data on this binary system of active amyl-isoamyl alcohol. EQUILIBRIUM STILL
Many types of vapor-liquid equilibrium stills are described in the literature; an Othmer still (10, 11,12) was used in this study. The specifications shown in Figures 1and 2 of Othmer’s previous paper (11) were followed in constructing the still. The precision of the equilibrium still and experimental technique were checked by st,udying the “standard” ethyl alcoholwater system. The vapor-liquid equilibrium data on this system indicated that the vapor composition was slightly richer in the
C. L. LOVELI, Piirdtce C n i w r s i t y , Lufayette, I n d .
niore volatile component, ethyl alcohol, than has been indicated in the reliable literature. This discrepancy was of a magnitude of 5 to 10% and v-ould be insignificant for most engineering purposes. I t was possible t o eliminate this slight error in the equilibrium data by the use of heating jackets over the outer vapor surface of the still. Insulated or jacketed stills were suggested by Othmer (IO, 1 1 ) , and such means for reducing internal refluxing have been incorporated into the design of equilibrium stills by other investigators (b, 3, 4, 7, 15). The heating jacket consisted of three separate heating coils-one for the long vertical neck, one for the body of the still lying between the internal heating coil plugs, and one for the body of the still below the plugs. Each circuit was made by winding chrome1 A wire, S o . 27 B. & S. gage, into loops spaced 6/16 inch apart; asbestos stiips prevented the wires from touching the glass surfaces. A thermocouple was placed between two of the middle loopa of each circuit. A heavy wrapping of glass wool on t i p of the heating circuits completed the assembly. Variable transformers were used to obtain proper heat input to the circuits, which were operated so that the temperature indicated by the thermocouples agreed within 3’ with the indicated vapor temperature. ,4t times a slight superheating of the vapor was noticeable and, therefore, vapor temperatures are not reported. The Othmer still thus jacketed gave equilibrium data that were comparable with reliable literature data. Unfortunately, the jacketed Othmer still “standardized” on the ethyl alcohol-water system cracked during subsequent runs, and attempts to repair it proved futile. Another modification of the still was blown in the laboratory which incorporated the features of the previous still found necessary for securing accurate equilibrium data. This still contained two changes in design. One change consisted of putting a single-turn helix in the vapor tube from the neck
