April, 1928
INDUSTRIAL AND ENGINEERING CHEMISTRY
of the buret stopcock. The clamp and lever naturally turn with the stopcock, resistance to this motion being supplied by the spiral spring, H . A metal finger, M, prevents the stopcock and lever from coming out of the barrel. The main frame, F, supporting the magnets is clamped down on the barrel of the stopcock, the clamp and set screw, K , giving additional support and also regulating the orifice. The orifice depends upon the angle which the device makes with the axis of the buret. With the device locked at the proper angle to give the desired rat& the stopcock is turned as usual, until the lever L presses the beveled end of P, and rests on its offset end. It is held in this position by the tension of the spring, H . The buret is now delivering, and when the magnets are engaged the armature carries the pin P to the left, releasing the lever L and with it the stopcock. The arrangement is small, neat, and positive in action. It can be adapted to any standard buret in a few moments and is easily constructed. It has been pointed out that most of the common indicators will work satisfactorily with this device, and that it is appli-
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cable to permanganate and dichromate titrations, using mphenylenediamine as an indicator for the dichromate, and also to iodometric titrations. The precision in every case was greater than that of visual estimation. It was also shown, though not checked accurately, that certain precipitation reactions can be followed in this manner-for instance, the determination of chloride ion by silver ion in the presence of chromate ion. In this case the light reflected from the turbid solution was used. The end point a t which the precipitate darkens, owing to the formation of silver chromate, is then characterized by a decrease in the amount of reflected light. This may be capable of accurate measurement, and work on this type of titration is in progress. I n most cases involving moderate turbidity, this method is applicable without any change in the apparatus. Adjustment of the light intensity must, of course, be made as in reactions in clear solution, so that the relay operates a t the desired end point. Any apparent lack of sensitivity may usually be remedied by increasing the intensity of the source of illumination.
Extractor for the Preparation of Oat and Other Cereal Oils’ L. A. Munro and D. S. Binnington AQRICULTURAL COLLEGE, UNIVBRSITY OP MANITOBA, WINNIPEG,CANADA
Oat oil has been prepared in relatively large quantiThe extraction chamber is URING the course of ties by means s f an extractor, which is described in rectangular, 2 by 3 by 3 feet, f e e d i n g experiments detail. This extractor is suitable for the preparation of 18-gage galvanized iron. relative to the softof cereal and other oils. It can also be used for the It has a false top and bottom. pork problem, a considerable distillation of approximately 20 gallons of liquid at The false top has ‘/2 inch quantity of oat oil was reone charging. It can be used for steaming materials perforations, flanged upward, quired. As this oil is not a or for the impregnation of substances with any desired causing the even distribution commercial product it was vapor. Last traces of solvent are removed from the oil of the reflux solvent over the necessary to prepare it. The by vacuum distillation. The extracted cereals can be material within the chamber. small amount of oil in oats used as stock food. The flanged holes are punched a t once suggested solvent exThis “technical” oil has a higher acid value than the traction as the method of on a softwood b l o c k , b y oil prepared very carefully by complete extraction with preparation. An e x t r a c t o r means of a l/Z-inch hollow ether. There is no oxidation of the “technical oil” was accordingly designed and punch. The false b o t t o m during preparation. constructed. This is inexhas 3/le-inch perforations. At pensive, can be built in a the corners of the chamber iery unpretentious mechanical department, and is very are vapor channels. Two manholes are provided as shown satisfactory in operation. In addition to its use for the in the figure. These are made from 8-inch pipe flanges, extraction of large quantities of materials containing a small threaded and fitted with plugs. The flanges are brazed on. amount of oil, it can also serve for the distillation of larger The plugs, when lubricated with glycerol, are gas-tight. I n volumes of liquids than can be handled conveniently in the the bottom of the chamber is a combined steam inlet and laboratory and for other purposes, such as steaming materials drain pipe. or impregnating them with a given vapor. The condenser consists of a cylinder of No. 22 gage galvanized iron, 4 feet 6 inches high and l foot in diameter. It Apparatus and Materials has ninety 3/lginch copper automobile-radiator tubes, 4 feet The apparatus (Figure 1) consists essentially of three parts: in length, soldered into disks at each end. The cooling water the drum, containing the solvent and extracted oil; the ex- flows through the interstices between the copper tubes, traction chamber; and the condenser. The three are con- giving very efficient condensation. In building the condenser, two disks of heavy galvanized nected by 2-inch pipe with gate valves, and by an outside iron which fit snugly into the condenser cylinder are first circuit of 1-inch pipe with valves. The drum is an ordinary steel oil (or gasoline) drum of 20 clamped together and drilled for the copper tubes. Each gallons capacity, equipped with an inlet, a tap outlet, and a tube is then fitted into the holes of one of the disks, being Pyrex gage glass. The contents are heated by a %inch allowed to protrude ’/4 inch, and is soldered in position. The steam pipe passing through the length of the drum and second disk is now affixed in a similar manner. The assembrazed into the ends. This system of heating is satisfactory bled condensing system is next inserted in the condenser for solvent boiling below 100’ C., but for higher temperatures casing and soldered by flooding around the edge of the disks. auxiliary heating must be used. The ends of the condenser are then put on, and the whole is tested. 1 Recdved October 3,1927.
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
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\Peiloroied Tor, f o o L W e n t Distrrbutlan
eri
Figure 1-Extraction
Apparatus for Cereal Oils
The solvent used for the extraction of oats was obtained from high-test gasoline, by collecting the fraction that distilled below 96" c. This distillation was done very conveniently in the apparatus. On closing valves 1, 2, 4, and 5, the vapor passes through 3, up the pipe, and entering the condenser at the top, is condensed and flows through 6 to a receiver. The residual gasoline was used for tractor fuel.
Vol. 20, No. 4
oats is allowed to stand in contact with the solvent overnight, followed by hot extraction for about 8 hours. The oats after 8 hours' extraction contain from 0.8 to 0.9 per cent of oil. The fresh oats contain 4.8 per cent oil. When extraction has been carried on as long as desired, the heating coil is shut off, valves 4 and 6 are opened, and 1, 5, and 2 are closed. Live steam is then blown into the extracted mass. The solvent vapor is driven off through No. 4 to the condenser, whence it flows through No. 6 to a receiving drum. When condensed steam commences to come over the solvent, the mixture flows into a separator, from which the solvent and water are removed by a system of continuous siphons. Any condensate in the vertical pipe is removed through a petcock in the elbow near No. 3 (not shown in diagram). Steaming for half an hour is sufficient to remove all but traces of solvent from the extracted oats. The steam is then shut off and the valve leading to the drain is opened. When sufficiently cool, the extraction chamber is emptied. The extracted oats are surprisingly dry and have no odor of solvent. This material is an excellent stock feed, the Animal Husbandry Department reporting that the stock eat it with relish. If it has to be stored for any length of time before consumption, drying is necessary to prevent molding. The foregoing procedure is repeated until the drum contains a fairly high concentration of oil. Solvent is then distilled off through valves 3 and 6, all others being closed, until a concentration of about 60 per cent oil is obtained. The drum also contains some oil-water emulsion with an oil content of 15 per cent, starch, and a small amount of other extraneous substances. These are partially removed by settling and passing the supernatant oil through a supercentrifuge. The oil still contains a small amount of suspended starch, which is removed by filtration through infusorial earth on large Buchner funnels. If the oil-gasoline solution contains less than 40 per cent gasoline, the viscosity is so great that the removal of suspended matter is difficult.
Preparation of Oat Oil
About 10 gallons of solvent are placed in the drum and valve 1 is closed. A double layer of cheesecloth is then placed over the false bottom and the lower manhole closed. The chamber is then charged with cracked oats. Cracked or coarsely chopped oats were used in preference to oat meal, although the latter contains a larger percentage of oil, because the finely ground meal forms a cake through which the solvent does not readily penetrate. While the extraction chamber is being charged, the steam is turned on the heating coil and valves 2 and 3 are opened, the others being kept closed. Any solvent that is vaporized before the chamber is charged passes through No. 3 to the condenser, and trickles through No. 2 to the chamber. When the chamber has been filled to within a few inches of the false top, 6 gallons of solvent are poured into the chamber. This thoroughly wets the oats and hastens extraction. Valve 1 is now opened and No. 3 closed. The hot solvent vapor passes through the charge and channels in the extraction chamber, through No. 2 to the condenser, and is refluxed, percolating evenly through the mass. Valve 5 is open to the air, as a matter of safety in case of failure of the water supply. Condensation is so complete that there is no loss of vapor through this open valve. The extractor requires no further attention. If no steam is available a t night, the fresh charge of cracked
Hyvoc
Fi&ure:Z-Apparatus
for Removing Solvent from Cereal Oils
After clarification, the oil is concentrated by distillation a t 100' C. a t atmospheric pressure. This removes all but about 10 per cent of the solvent. The use of steam is impractical because of the formation of a heavy oil-water emulsion, and the hydrolysis of some of the oil. The method used is vacuum distillation. The distillation is carried out in a 12-liter Pyrex flask im2) The flask is connected mersed in an oil bath. (Figure . -
INDUSTRIAL A X D ENGINEERING CHEMISTRY
April, 1928
to a spiral condenser, which is built into a modified Perkin triangle, permitting the removal of distillate without breaking the vacuum. The triangle, which is equipped with a manometer, is attached to a block-tin condenser containing a calcium chloride hydrate freezing mixture to remove any solvent vapor. This condenser is connected with a Hyvac pump* Most of the residual solvent can be removed by slowly bubbling carbon dioxide through the heated oil, so that the pressure remains around 5 to 10 mm. For the removal of the last traces of solvent (below 0.5 per cent) it has been found advisable to allow the pressure to go as low as possible and then to admit a little gust of the gas. The temperature is gradually raised to 140' C. and the process repeated until no more solvent will come over. Properties of Extracted Oil
The oil obtained by this method is a clear, dark green oil, yellowish green in thin layers. It has an odor faintly reminiscent of oat meal. The constants of the oil thus prepared are given in Table I, column 1. It was essential for our purpose that the oat oil so obtained should not have undergone any oxidation or change in iodine value. I n order to test the above method, 20 pounds of fresh chopped oats were dried in a vacuum oven for 48 hours a t 35" C. and then extracted with anhydrous ether. After extraction the ether was removed by a current of carbon
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dioxide a t 100" C. The iodine number of the oil thus prepared was 105.0, whereas the "technical" oil had a value of 107. These values show that the oil prepared in the extractor did not undergo oxidation during any part of the process. The acid value of the "technical" oil appeared rather high. The ether-extracted oil gave an acid value of 21.1. This agrees with Berry,2 who states that the free fatty acids are negligible, but that hydrolysis occurs, depending on the time between grinding and extraction. It is probable that hydrolysis has also taken place during the initial stages of extraction, since the cracked oats were undried and some water was found in the drum after several extractions. It is probable that hydrolysis can be inhibited by extracting immediately after cracking or chopping. The constants for oat oil prepared on a laboratory scale by different workers are given in the accompanying table. It will be seen that the acid values of all are considerably higher than that of the ether-extracted oil. Table I-Constants for Oat Oil "TECHNICAL" DUBOPAUL^ CON5TANT OIL VITZa (15/15O Specific gravity, 25/25' C. 0.9191 0.9110 0.925 Refractive index at 20' C. 1.4710 1.4706 1.4635 Iodine number (Wijs) 107.2 91.7 114.2 Saponification number 190 6 180.1 189.8 Unsaponifiable matter, per cent 2.26 1.61 1.30 Acid value 89.1 62.11 68.9 a Chcm.-Ztg., 42, 13 (1918). b Analyst, 46, 138 (1921).
c.)
2
STELLWAAGh
... .. . ...
192.4 2.65 70.26
J. Agr. Sci., 10, 366 (1920).
Direct Determination of Rubber in Soft Vulcanized Rubber' A. R. Kemp, W. S. Bishop, and T. J. Lackner BELLTELEPHONE LABORATORIES, INC., 463 WEST ST., NEW Y O R K , X. Y.
r;bber and g u t t a - p e r c h a parison. based upon the additive reaction of iodochloride (Wijs solution) with their hydrocarbons. It is the purpose of the present paper to describe a modification of this method for determining the rubber content of soft vulcanized rubbers. Although several direct methods3 are described in the literature, none of them have been found entirely satisfactory. A widely used method for determining the rubber content in vulcanized rubbers is that recommended by the Committee on Methods of Analysis of the Division of Rubber Chemistry of the AMERICANCHEMICALSOCIETY.~ This method is a complicated one and consists in determining the non-rubber constituents and taking rubber by difference. As mentioned in the committee report, the method is inaccurate in the presence of decomposable inorganic constituents, cellulose, or high percentages of mineral rubber. 1 Received
October 25, 1927. 2 Kemp, I n d . Eng. Chem., 19, 531 (1927). 8 Alexander, Gummi-Ztg., 18, 789 (1904); Axelrod, J . SOC. Chcm. I n d . , 26, 1058 (1907); Lewis and McAdams, J . I n d . Eng. Chem., 12, 673
(1920). 4 Ibid., 18, 397 (1924).
resins, free sulfur, oils, waxes, organic accelerators, age resistors, part of the mineral rubber, etc., followed by further removal of a portion of the mineral rubber with chloroform. A sample of the extracted residue is then dissolved in tetrachloroethane and the hydrocarbon present in the unsaturated state determined by the modified Wijs method.2s6 In order to determine the amount of hydrocarbon saturated with sulfur, a direct determination of sulfur combined with rubber is made on another portion of the extracted sample. The sum of the hydrocarbons in the unsaturated and combined states is then used to calculate the rubber content of the original sample. Experimental Procedure
The acetone and chloroform extractions are carried out on 2-gram samples according to standard p r ~ c e d u r e . ~The chloroform is removed by heating in a vacuum oven a t 70" C. to constant weight. An alcoholic alkali extraction is also conducted on one of the extracted samples to detect the 5
Fisher, India Rubber World, 76, 78 (1927).
