VOL. 8, NO. 4
INDUSTRIAL AND ENGINEERING CHEMISTRY
252
Results with the Method I n Table VI1 are given determinations on silicates and fluorine-containing minerals. The two results on phlogopite check closely; no theoretical figure for fluorine is given, as the fluorine content of phlogopite varies. Results on gearksutite and creedite are much closer to the calculated theory than previous determinations. Bureau of Standards standard sample 91 gave a figure in fair agreement with the result obtained by Hoffman with the lead chlorofluoride method. In topaz hydroxyl replaces fluorine, so that no theoretical figure for fluorine is given. The topaz listed is unusual in having a high water content (2.67 per cent of combined water) WITH TABLE VII. RESULTS
Sample
Locality
THE
METHOD
Fluorine Found Theory
Results by Other Methods
% 1. Phlogopite
Kin& Mountain,
2. Fluorite 3. Gearksutite
Rosiclare, Ill. Wagon Wheel Gap, Colo. 42.30 42.9
N. c.
4 31 ... 4.34 4 8 . 6 5 48.68
...... . . .... Average of results bv three
4. Creedite difference, 30.35 5. Bureau of Standards standard sample 91, opal glass
... Jefferson, S. C.
6. Topaz
13.23
...
....
and hence a low fluorine content (13.23 per cent). The complete analysis gave a summation of 100.13, after subtracting the oxygen equivalent of the fluorine.
Literature Cited Armstrong, IND.EXG.CHEM.,Anal. Ed., 5 , 300-2 (1933). Barr and Thorogood, Analyst, 59, 378-80 (1934). Berzelius, Schweigg. J., 16, 426 (1816). Fairchild, J . Washington Acad. Sci., 20, 141 (1930). Foster, IND.EXG.CHEM.,Anal. Ed., 5 , 234 (1933). Hillebrand and Lundell, “Applied Inorganic Analysis,” p. 601, New York, John Wiley & Sons, 1929. Hoffman and Lundell, Bur. Standards J . Research, 3, 581 (1929). Knoblock, Pharm. Ztg., 39, 558 (1894). Reynolds and Jacob, IND.ENQ.CHEM.,Anal. Ed., 3,366 (1931). Reynolds, Ross, and Jacob, J . Assoc. Oficial Agr. Chem., 11, 225 (1928). Sanchis, IND.ENG.CHEM.,Anal. Ed., 6, 134-5 (1934). Snell and Snell, “Colorimetric Methods of Analysis,” New York, D. Van Nostrand Co., 1936. Starck, Z . anorg. Chem., 70,173 (1911). Starck and Thorin, 2.anal. Chem., 51, 14 (1912). Steiger, J . A m . Chem. Soc., 30,219 (1908). Thompson and Taylor, IKD. ESG. CHEM.,Anal. Ed., 5, 87-9 (1933). Washington, “Chemical Analysis of Rocks,” p. 264, New York, John Wiley & Sons, 1930. Wilcox, IND.ENG.CHEM.,Anal. Ed., 6, 167-9 (1934). Yoe, “Photometric Chemical ,4nalysis,” New York, John Wiley & Sons, 1929. RECEIVED March 11, 1936. Presented before the Division of Physical and Inorganic Chemistry at the 91st Meeting of the American Chemical Society, Kansas City, Mo.. April 13 to 17, 1936. Published by permission of the Director, U. S. Geological Survey.
Microvaporirnetric Determination of Molecular Weight JOSEPH B. NIEDERL, OTTO R. TRAUTZ, AND ALBERT A. PLENTL Washington Square College, New York University, New York, N. Y.
I
N 1929 Niederl (26) described a simple microvaporimetric
method for the determination of the vapor density or the molecular weight of low-boiling liquids. This method was improved (29) so that the results were within *2 per cent of the theoretical (%$,a?) ; consequently, its application to higher boiling substances for temperatures up to 200” C. was investigated (28). But the difficulty of obtaining temperature constancy increased proportionally with the rise in temperat u r e . 80 m u c h so that such
i m p r o v e m e n t s as
fused-in
thermometer and other s u i t able c h a n g e s i n a p p a r a t u s did not appreciably i n c r e a s e t h e a c c u i a c y of the results. F u r t h e r experimental studies led the ment of a method for temperatures up to 320” C., retaining all the f a v o r a b l e feat u r e s of the low-temperature m e t h o d , s u c h a s v i s u a l observation Of the and c o n d e n s i n g point, as well as r e p e t i t i o n , and t o the cons t r u c t i o n of the improved,
’’
yet extremely simple and inexpensive apparatus as set forth in this communication.
Principle of the Method A few milligrams of a substance, either liquid or solid, are vaporized in a closed system in such a way as to permit an
accurate indirect volume determination with suitable provisions for pressure and temperature control and constancy a t any point for a temperature range of 300” C. The previously described micromethod The m e t h o d is n o t merely
for determining Of lowboiling liquids has been suitably modified to include high-boiling liquid and solid substances of various types. The obtained compare favorably with any of the existing macro- Or micromethods based upon similar principles. The method, in addition to the determination of the moleclllar weight, permits repetition as well as simultaneous observation of the boiling and condensing Point O n a single Sample of a few milligrams in weight.
a miniature m a c r o m e t h o d , but may be c o m p a r e d w i t h t h e c l a s s i c a l vapor density m a c r o m e t h o d s of Hofmann (16) and Meyer (22). Mer-
cury, t h e s e a l i n g fluid, is d i s p l a c e d i n s t e a d of air as in the older m e t h o d . Both methods (9, 11, 32) and to a lesser degree their many modif i c a t i o n s (3, 6, 6-8, 10, 15, 18, 20, 21, 23, 30) a s w e l l a s the vapor d e n s i t y method of Dumas (12) and others (31)
JULY 13, 1936
I
ANALYTICAL EDITION
233
a thick-walled round-bottomed flask and while attached to a water suction pump it is heated in an oil or sand bath to 250" C.
I
Preparation of the Sample
I 1-I , 1
SOLIDS. Soft-glass capillaries not less than 1.5 mm. in inner diameter are prepared by drawing out either soft-glass test tubes in a blast lamp, or soft-glass tubing in a wing burner. These capillaries are then cut to about 8 to 9 cm. in length (Figure 2, No. 2 ) . One of the capillaries, the outside of which is cleaned by drawing it through a clean piece of cotton fabric, is weighed to the nearest 0.001 mg. The reproducibility of the weighings need not be greater than *0.005 mg., and any microchemical balance showing this sensitivity a t a load of from 0 to 1 gram can be used for this determination. Such capillaries weigh usually about 150 to 200 mg. and are counterpoised by either another capillary or the standard weights. The solid substance to be analyzed is now melted on a microscope slide, on a watch glass, or in a capillary of wider bore. The weighed capillary is brought into contact with the molten substance which by capillary attraction is allowed to rise in the capillary to a height of not more than 4 mm. The capillary with the molten substance, 3 to 9 mg., is then withdrawn and allowed to cool. If no crystallization takes place upon cooling, the capillary is dipped for a moment into the remaining solid sample. After crystallization, the outside of the capillary is cleaned, and it is weighed again as described. If the substance is a solid, which does not melt but sublimes, the capillary as prepared above is sealed at one end and weighed in this condition (Figure 2, No. 3). The sample is then introduced as in the taking of melting points. To ensure compactness, the capillary is allowed to drop on a glass surface through a vertical glass tubing at least 1 meter in length. Cleaning and weighing of the capillary thus prepared are done as described above. LIQUIDS. Liquids of high viscosity or semi-solids may be introduced in the same way as crystalline solids, using capillaries open a t both ends (Figure 2, No. 2). Otherwise li uids are introduced by means of capillary weighing pipets ?I) prepared according to Pregl (33,34, omitting the potassium chlorate (Figure 2, a, 6, c ) . These weighing pipets, however, should be shorter and of wider inner diameter (2 mm.).
L'
'V
have found their application in quantitative organic microanalysis (4).
Apparatus The apparatus consists of a round-bottomed Pyrex flask, F, which in 7 to 8 om. in diameter and has a capacity of about 350 cc. Its neck (7 to 8 cm. long) is not in the center but tangent to the flask surface and has an inner diameter of about 2 cm. By means of an interchangeable ground-glass (No. 15) joint either a Liebig water condenser or a plain air condenser, C, of inner diameter large enough (10 to 12 mm.) to permit the insertion of a thermometer, T , and about 50 cm. in length, is connected to the flask, which serves as the container of the bath liquid. The Pyrex glass vaporimeter, VI consists of the vaporizer which has the shape of a slightly elongated (egg-shaped) bulb, B , of from 12- to 115-cc. capacity and the hollow stem, SI which is 11 cm. long. Its inner diameter is 6 mm. The glass bulb, B, is attached to the hollow stem, S , at an angle of about 45". It is important that thle inner diameter of the bend between the vaporizer and the stem be slightly larger (7-mm. inner diameter) than the inner diameter of the rest of the stem. The capillary outlet tube, 0, is also bent at an angle of 45" and has an outer diameter of 5 mm. and an inner diameter of 2 mm. Its horizontal arm is about 10 cm. long, while its oblique arm together with the interchange%ble, hollow ground-glass joint, J (No. 5), is 5 cm. long. Between this glass joint and the bend there are also two glass hooks, IY',for the attachment of steel springs leading to the glass hooks of the stem, thus preventing any loosening of this connection during the experiment. The entire vaporimeter, V , which thus asm.lmes the form of a curved pipe, is fused into the heating flask opposite its neck at an angle of about 45" in such a manner that the glass bulb, B, is fairly in the center of the heating flask, F. The orifice of the ground-glass joint extends at least 5 cm. above the heating jacket. The thermometer, T , is introduced through the condenser, C, into the bath liquid and is held in position by means of a fine flexible wire. A centrifuge tube of about 15-cc. capacity, which is bent downward below the side arm at an angle of about 45", serves as the receiver, R, for the displaced mercury. By means of a suitably bent wire this receiver is attached to the top hook of the weighing pan of the analytical balance. This and all the previously described apparatus were made by Eck and Krebs, 131 West 24th St., New York, N. Y., who together with Eimer and Amend, Third Ave. and 18th St., New York, N. Y., are able to supply these instruments a t reasonable cost.
Reagent
Procedure ISTRODUCTION OF THE SAMPLE. The bath liquid is first removed from the flask and placed in a suitable container for re-use, and the flask is stoppered. The capillary outlet tube is detached, by first removing the steel springs and then slowly withdrawing it from the ground-glass joint, holding the apparatus over a trough or other device to collect any spilled mercury. The mercury from the vaporimeter is emptied into a suitable bottle, and at the same time the capillary, which served as the container of the substance, is removed. A little acetone (about 1 to 2 cc.) or other volatile organic solvent is introduced into the vapor-
-
a
C
d I
1
4 I
1
The imercury used as the sealing liquid must be free from volatile substances. Of the many purification procedures for mercury, the following was found to be entirely adequate:
I I
I
I
2
8
)&WY I
I
Mercury (commercial, c. P., or reclaimed) is allowed to fall in a fine stream through a column of dilute nitric acid (10 per cent) or concentrated sulfuric acid. After separation it is treated in a similar manner with water, then with acetone and finally again with distilled water. After separation, the mercury is placed in
3
.'.;.:.\
I
i FIGURE 2. WEIGHINGCAPILLARIES
254
VOL. 8 , NO. 4
IYDUSTRIAL AND ENGINEERING CHEMISTRY
imeter1 and the apparatus is well shaken, while the opening of From the amount of mercury displaced at several temperathe vaporimeter is closed with the finger or a small cork. The ture Points (three are sufficient) a graph may be plotted, solvent is removed and this operation repeated at least three from which the amount of mercury collected from this partimes. The apparatus is then placed in an oven at about 1000 c. and while still warm the outlet of the vaporimeter is attached to ticular apparatus may be ascertained for any temperature a suction pump to ensure the complete removal of the solvent. up to the boiling point of mercury. The sample to be analyzed is introduced into the cooled apparatus as follows: Calculation Solids. The weighed capillary, open at one or both ends, is cut about 2 mm. above the substance. This section of the capil~t (273.2 Tz) lary, the entire length of which should not be more than 8 mm. M = 62351 vp (Figure 2, Nos. 2 and 3), or short enough so that it can pass the = weight bend of the vaporizer, is allowed to slide into the bulb of the wt = weight of sample vaporimeter. T2 = Liquids. The stem o f the capillary ipet is cut off just below the center bulb, and the pipet is centrifuged to remove all liquid E : 9 - k l (Tz - TI11 - 218 from its hair-fine end. While the pipet is held at this hair-fine d ending, it is cut just above the center bulb (Figure 2, No. 1) V = volume of vapor and the bulb containing the substance is allowed to slide into g = weight of displaced mercury the vaporizer. Special precautions are necessary for very volatile c1 = correction for expansion per 1" C. liquids, such as diethyl ether, divinyl ether, acetaldehyde, etc. TI = initial temperature, C. In this case, previous to the introduction of sample, ice water is Tz = final temperature, ' C. introduced into the flask which is then stoppered. The mercury d = density of mercury at Tz and the sealed and weighed capillary are cooled similarly. FILLING THE APPARATUS.Mercury, cleaned and dried as (weight) described above, is poured into the vaporimeter while the entire IrS E Of the (density) (approximately mm. apparatus is held or placed in a suitable trough. This filling Per mg.1 o eration is accomplished with a minimum of spilling by using a P = p l +pz - p3 p $ells-Ringer flask or similar device having double outlets, one of which has a fine opening. By proper tilting of the flask, P = pressure of vapor the entire bulb and then the entire stem up to the ground-glass pl = barometer reading joint are easily filled with mercury. The joint of the capilp z = vertical distance in mm. between the mercury meniscus lary outlet tube is greased lightly and the tube is inserted into in the vaporiaer and the orifice of the capillary outlet the stem of the vaporimeter, thus filling the outlet tube with tube mercury to about one-third. The steel springs are then atps = vapor pressure of mercury a t T2 tached. The outlet tube is filled completely with mercury p = capillary depression of mercury in outlet tube (+ 8 mm.); by means of a pipet, prepared by drawing out an ordinary glass temperature reduction of barometer (-2 mm. at 15" C., tubing to a capillary, fine enough so that it fits about 2 cm. -4 mm. a t 32" C.); density reduction of mercury in into the capillary outlet tube. This pipet has a rubber cap and stem of vaporimeter for that portion of the stem of by proper inflation a small amount of mercury is drawn into the vaporimeter which is inside of heating chamber ( - 1 mm. pipet. The pipet is then inserted into the capillary outlet tube for TZ= 100' C., - 2 mm. for TZ= 180" C., -3.5 mm. and a small amount of mercury introduced by the application of for Tt = 320" C.) pressure t,o the rubber cap. The column of mercury so introduced The net value of P is usually small (about f0.5 Per cent of can be made to join the mercury column in the capillary outlet tube P ) and within the limits of accuracy and precision of this method, by introducing and withdrawing a fine wire (copper, platinum, therefore, for practical purposes this correction may be omitted. etc.). Repetition of this operation soon fills the outlet tube completely with mercury. Finally, the weighed receiver is attached to the capillary outlet as shown TABLE I. TYPICAL MOLECULAR WEIGHTDETERMINATIONB in Figure 1 and the entire apparatus is laced on (Results obtained by students while learning the method, 86) asuitable stand, provided with a ring ckmp and Molecular Weight wire gauze. The bath liquid is next introduced, and should about two-thirds of the bulb of the Substance Bath Liquid weight Tn Found Me. Cu. mm. vaporimeter. Small pieces of porous tile or boiling 32 5.556 4.585 25 100 852 33 point capillaries are added and the condenser is Methyl alcohol Water 4.552 2.666 25 100 852 46 46 attached (air condenser for bath Iiquids boiling ~ ~ ~ $ ~ & p - ~ y$ m e~n e~ e 3.047 0.625 27 180 839 164 157 above 170" C.). A t h e r m o m e t e r is introduced Propionic acid 2.779 0.729 24 180 850 128 130 through the condenser into the bath liquid so that anhydride a-Naphthyl 4.533 1.372 31 269 730 153 156 its mercury bulb is completely immersed, and is methyl ether held in this position by means of a flexible wire 6.062 2.135 28 267 750 128 128 (copper, etc.). In order to attain equilibrium of Naphthalene 7.899 2.449 28 268 740 147 150 temperature, the apparatus is allowed to remain in ~ ~ ~ ~ & l C O h O l 10.125 4.007 25 268 764 110 108 this condition for about 5 minutes, after which period Diphenyl amine Benzyl ben9.170 4.016 29 318 499 169 169 zoate the starting temperature, T I ,is read. Any mercury 3.096 1.952 25 319 503 119 122 Benzoic acid that may have entered the receiver is removed and el, 0.028 gram of mercury the receiver re-attached. d (19) Pa (19) O c : HEATING. After the initial starting temperature, 100 13,352 ...9 T I , has been ascertained, the apparatus is heated 180 13.160 rather rapidly up to near the boiling point of the 270 12.947 123 368 320 12.829 bath liquid. The heating may be accomplished electrically, by applying a free flame, or using suitable heating baths (oil, sand, or Wood's metal bath). As soon as the Further Modifications of Method bath liquid begins to boil, the heating is reduced to a minimum and the boiling is continued for exactly 2 minutes, at which time the vapors Of the substance are not in contact the thermometer inside the condenser is again read to give the with air, a fact which kSSenS the danger of possible oxidation, end temperature, yZ. After this readin the heatin is disconthey are under a pressure greater than atmospheric (about tinued and the entire a paratus allowecf to cool. ?he receiver containing the displacef mercury is removed and weighed on an 100 mm.). This pressure, however, may be diminished through ordinary analytical balance to *0.01 gram. partial evacuation, by attaching the side arm of the receiver to a suction pump with provision for the maintenance of a CORRECTION FOR HEATEXPANSION OF APPARATUS. By constant although lower pressure (300 mm.! etc.). The deperforming the experiment as described above, b u t using a n termination may be repeated on the same sample by attachempty capillary without a sample, it is possible to determine ing a side-arm test tube containing sufficient mercury t o the how much mercury is expelled by heat expansion of the mercury a n d glass and by other minor factors, cl(Tz TI), orifice of the capillary outlet tube at the end temperature, T1,and allowing the apparatus to cool. After cooling, an while t h e apparatus is heated from TI to TP,
+
v
+
-
JULY l!i, 1936
ANALYTICAL EDITION
equivalent amount of mercury, which can be determined quantitatively, is drawn back into the apparatus. The filling of the vaporizer may be carried out also by evacuation of the vaporimeter already containing the nonvolatile sample and by suitable arrangement allowing mercury to enter this portion of t8heapparatus. T h e boiling and condensation points, which can be simultaneously observed and ascertained, are comparable with the results obtainable with other micromethodri already known (%’,5 , is, 14, i7, 35-32?), corrections for the higher pressure, p , and pz, being necessary. By slightly enlarging the bulb (vaporizer) of the vaporimeter without changing the apparatus otherwise, larger samples (10 t o 20 mg.) can be used which need to be weighed only to *0.05 mg., a precision obtainable with a n y good macrochemical balance, eliminating the use of a microchemical balance.
Literature Cited (1) Berredetti-Pichler, A. A., and Spikes, W. F., “Introduction to the Micro Technique of Inorganic Qualitative Analysis,” Douplaston, N. Y., Microchemical Service, 1935. (2) Biltz, H., Ber., 30, 1208 (1897). (3) Blackman, Ph., J. Phys. Chem., 11, 681 (1907); 13, 532, 606 (1909); 15, 869 (1912); 24, 225 (1920); Be?., 41, 414, 768, 881, 1588, 2487 (1908). (4) Blank, E. W., Mikrochemie, 13, 149 (1933). (5) Bleier, P., and Kohn, L., Monatsh., 20, 505 (1899). (6) Booth, H. S., IND.ENG.CHEM.,Anal. Ed., 2, 182 (1930). (7) Booth, H. S., and Jones, H. C., Ibid., 2, 237 (1930). (8) Booth, H. S., and Willson, K. S., Ibid., 4, 427 (1932). (9) Bra,tton, A. C., and Lochte, H. L., Ibid., 4, 365 (1932). (10) Chapin, J. Phys. Chem., 22, 337 (1918). (11) DeCeuster, P., Natuurw. Tijdschr., 15, 189 (1934). (12) Dumas, A., Ann. chim., (2) 33, 342 (1826).
255
(13) Emich, F., Monatsh., 38, 219 (1917). (14) Emich, F., and Schneider, F., “Microchemical Laboratory Manual,” New York, John Wiley & Sons, 1932. (15) Henderson, W. E., J. A m . Chem. SOC.,34, 553 (1912). (16) Hofmann, A. W.. Ber., 1, 198 (1868); 9, 1304 (1876); 2. anal. Chem., 8, 83 (1869); 16, 479 (1877). (17) Jones, H. C., J. Chem. Soc., 33, 175 (1878). (18) La Coste, W., Ber., 18, 2122 (1885). (19) Landolt-Bornstein. “Physikalisch-Chemische Tabellen,” Vol. I, p. 76; Vol. 11, p. 1335, Berlin, Julius Springer, 1923. (20) Lumsden, T. S., J. Chem. Soc., 83, 342 (1903). (21) Lunge, G . , and Neuberg, O., Be?., 24, 729 (1891). (22) Meyer, V., Ibid., 9, 1216 (1876); 10, 2068 (1877); 11, 1867, 2254 (1878); 2. anal. Chem., 16, 482 (1877); 17, 373 (1878); 18, 294 (1879). (23) Nernst, W., Nachr. hgl. Ges. Wiss. Gilttingen, 1903, 75-82. (24) Niederl, J. B., IND.ENQ.OHIDM.,Anal. Ed., 7, 214 (1935). (25) Niederl, J. B., J. Chem. Education, 13, 254 (1936). (26) Niederl, J. B., 2. anal. Chem., 77, 169 (1929). (27) Niederl, J. B., and Niederl, V., “Laboratory Manual of Quantitative Elementary Organic Microanalysis,” in preparation. (28) Niederl, J. B., and Routh, I. B., Mikrochemie, 11, 251 (1932). (29) Niederl, J. B., and Saschek, W. J., Ibid., 11, 237 (1932). (30) Peak, D. A., and Robinson, R. A., J. Phys. Chem., 38, 941 (1935). (31) Petterson, O., and Eckstrand. G., Be?., 13, 1191 (1880). (32) Porter, C. W.. J. Am. Chem. Soc., 34, 1290 (1912). (33) Pregl, F., and Fyleman, E., “Quantitative Organic Microanalysis,” Philadelphia, P. Blakiston’s Son & Go., 1930. (34) Pregl, F., and Roth, H., “Die quantitative organische Mikroanalyse,” Berlin, Julius Springer, 1935. (35) Richter, P h a m . Ztg., 56, 436 (1915). (36) Schleiermacher, A., Ber., 24, 944 (1891). (37) Siwoloboff, A., Ibid., 19, 795 (1886). (38) Yamaguohi, Y. Z., J. Pharm. SOC.Japan, 434, 252 (1918).
RECEIVED April 27, 1930. Presented before the Microchemical Seotion at the 91st Meeting of the Amerioan Chemical Society, Kansas City, Mo., April 13 to 17, 1930
Saponification Numbers of Asphaltic Petroleum Residues Pressure-Agitation Method JOHANNES H. BRUUN
AND
LAWRENCE W. CLAFFEY, Sun Oil Company Research Laboratory, Norwood, Pa.
T
HE: determination of the saponification numbers of the black asphaltic residues encountered in the petroleum industry is a procedure which is well known to be fraught with .difXcult8ies. Methods too numerous for reference have been devised. T h e most successful procedure has been that of adding benzene to the sample (i),which renders it soluble throughout the saponification and results in a two-layer titration medium, the end point of which can be seen with fair accuracy b y means of a titration pipet (3). However, in order t o obtain complete saponification it is sometimes necess a r y to boil the benzene-alcoholic solution under reflux for an undue length of time. Furthermore, the benzene layer, in which is dissolved the dark-colored material, remains on top of the lighter colored layer which contains the excess alkali .and must be titrated. These disadvantages made apparent the need for a method whereby the time required for a complete saponification could be shortened and a dissolving medium employed which not only would be miscible with t h e asphaltic material, but also would become viscid enough at titration temperatures t o hold it a t the bottom of the flask.
Analytical Procedure A weighed sample of the heav semi-solid asphaltic residue is mixed with a known amount (alout 1 to 2 parts) of white oil,
araffin oil, or similar oil (viscosity about 80 to 85 seconds Saygolt at 54.44’ C., 130’ F.). A liquid mixture is obtained which may be conveniently handled by means of a medicine dropper. About 3 to 4 grams of this mixture are weighed into an ordinary glass pressure flask, 50 to 100 ml. of 0.05 N anhydrous alcoholic potassium hydroxide are added, and the flask is placed in a shaking device (Figure 1) where it is agitated at 100’ C . for 30 to 60 minutes. At this temperature the viscosity of the asphaltwhite oil mixture is greatly reduced, with the result that a more
U
C
S
~ R~ E D ~ Vo CC~
FIGURE 1. SHAKING DEVICE
