December 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
of all undissolved water. I n order t o provide a niargin of safety in this respect and t o prolong drum life, i t is also desirable t o reduce the water content of the bromine below the saturation level of about 0.03weight %. It was found t h a t the water content of bromine could readily be reduced to below 0.01 weight yo by passing the bromine down through a packed tower cohtaining sulfuric acid of 60 weight % concentration or greater. Sulfuric acid of 80 weight Yo concentration gives a product containing about 0.003 weight % water. Concentrations greater than 80 weight % are not recommended because they do not further reduce the water content appreciably and tend to promote entrainment of the acid in the bromine. No trace of sulfuric acid was detected in the bromine dried with the 80% acid.
2797
ACKNOWLEDGMENT
The author wishes t o express appreciation to Dwight Williams for helpful suggestions and criticisms during this investigation; to w. E*Yates who the negotiations with the Bureau of Explosives, leading t o acceptance of these bromine drums; and to D. K. Chapman, J. H. Fisher, F. D. Heinde], and W. G. Strunk all of whom assisted with the experimental work. LITERATURE CITED
(1) Anon., Chem. & Met. Eng., 51,94-134 (1944).
(2) Woldman, N. E., and Metzler, R. J., “Engineering Alloys,” Cleveland, Ohio, American Society for Metals, 1945. RECEIVED April lQ, 1949.
Preferential Wetting of Cotton Fabrics IRVING REICH AND FOSTER DEE SNELL Foster D . Snell, Inc., 29 West 15th St., New York 11, N. Y .
A
~
CHALLENGING probA technique for measuring preferential wetting of a ance requires the applicalem for the physical fabric at an oil-water interface is described. It involves distion of broad concepts which, placement of oils from the fibers. Sinking time to pass chemist today is the analysis while not new, were not really through the interface is measured. Preliminary results of detergency into its comneeded until the advent of show molecularly dehydrated phosphates to be much ponent physicochemical facthe newer agents. more effective than other salts. That highly polyvalent tors. Surface tension, interions are responsible is confirmed by results obtained with facial tension, foaming power, PREFERENTIAL WETTING and ability to disperse pigpotassium ferrocyanide and sodium carboxymethylcellulose. Sodium lceryl benzene sulfonate with molecularly ments have been studied. Interfacial tension between One would be optimistic to dehydrated phosphates shows poorer wetting than the oil and detergent solution say t h a t they had been corphosphates alone. The method measures an important is only one of the forces physicochemical property fundamental in detergency. related. which govern the displaceTo some extent the diffiThe technique as described is considered useful, but furment of an adhering oil layer ther investigation is desirable to increase its precision. culty is a semantic one. Defrom a surface. Others are tergency is the separation of the interfacial tensions besoil from a surface. Untween the solid and the two liquids. It is entirely conceivable doubtedly different principles may be applied t o achieve that separation, just as different principles may be applied to achieve t h a t a surface-active agent will lower the interfacial tension between water and oil without at the same time increasing the separation of iron filings from granulated sugar. The difficulty tendency of the water to wet preferentially the solid surface and is real in that the physical process of removal of ordinary soils displace the oil. Indeed it may actually increase the preferential from specific surfaces by such common detergents as soap is but wetting tendency of the oil. I n t h a t case the agent may aid reimperfectly understood. moval of loosely held soil and of the bulk of oily coatings by the Most studies of the mechanism of detergent action have been rupture of oil-oil bonds under agitation, followed by emulsificabased on soaps of various types as the primary detergents. One tion. However, much of the soil will remain bound even more of the authors (10)has considered ordinary soil t o consist of variegated particles of matter coated with thin oil layers, so that the firmly t o the surface. This occurs when soaps are used on metal surfaces which are soiled with mineral oil or when cation-active particles behaved like minute oil droplets. Detergency with soap and alkaline salts was regarded as preferential wetting of the agents are used on glass or cotton surfaces (7). surface by the detergent solution, with consequenk displacement Any complete understanding of detergency requires that t h e of oil and oil-coated solid particles, followed by dispersion, conrole of the surface be taken into consideration. It follows t h a t sisting of deflocculation plus emulsification of the displaced soil. physicochemical methods which involve detergent solution and This second stage is necessary if the soil is t o be rinsed away soil alone cannot form the basis for a complete theory of deterrather than redeposited on the surface. gency. That is even more true for methods which involve the Preferential wetting was measured by the interfacial tension of detergent solution alone, such as surface tension or foaming. the detergent solution against benzene containing oleic acid (11) Such methods are useful nevertheless as screening tests andevaluaand dispersing power in terms of the amount of a lightly oiled tion tests when the detergents and surfaces are restricted as t o umber soil which remained in dispersion for a specified time after types. agitating the soil with the detergent solution (18). The diagram in Figure 1 shows a drop of water on a solid surMany of the newer synthetic detergents and building agents act face under a bath of oil. The lower the contact angle, e, the more differently from soaps (14). An understanding of their performeffectively the water solution displaces the oil. If the angle 6 is
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
2798
greater than go", the oil will tend to wet preferentially the surface and displace the TT-ater. Angle 8 is specified by the equation
where
S,, = interfacial tension between solid and oil E,
= interfacial tension between solid and water So, = interfacial tension between oil and water
Thus the angle 0, which governs preferential wetting, depends not on So, alone, but on the relative magnitudes of all three interfacial tensions. Detergency, in so far as it involves displacement of oil from solid surfaces by water, has been considered to depend on a low value for 8 (1,8).
Vol. 41, No. 12
Equation 2 fails when e becomes zero, because then it is impossible to determine whether mechanical equilibrium among the interfacial tensions exists. Application of the theor:- to practical problems of preferential wetting, and especially t o detergency, is hindered by two drawbacks. One is the failure of Equation 2 when 8 equals zero. The other is the difficulty in obtaining reliable interfacial contact angle measurements, especially on single fibers. A simple method which averaged preferent,ial wetting tendency over a large surface or a large number of fibers would he of great practical value. The method described below is not yet suitable for very precise work but has yielded highly int'eresting preliminary results. Among the more common wetting tests for fabrics are the Draves (31,Herbig ( 4 ) , and canvas-disk (9) procedures. Each of these can be used as the basis for an analogous mater-oil preferential wetting test? the dist'inction being t)hat the fabric is soaked lvith oil before it contacts the mater. The method chosen is analogous t'o the canvas-disk test. A swatch of fabric is placed a t a water-oil intcrface and it floats a t that interface until enough of the oil is displaced from among the fibers by water solution, whereupon it sinks. The time required for sinking is measured. PROCEDURE
Figure 1. Drop of Water on a Solid Surface under a Bath of Oil
This theory requires amplification. The tendency of a liquid t o wet a surface in air is a function of the contact angle of the liquid on that surface and the surface tension of the liquid ( 6 ) . This tendency is the decrease in free energy per unit surface wetted. Free energy per unit area has the dimensions of force per distance and can be looked upon as force of wetting, just as surface free-energy can be considered as a force per distancenamely, surface tension. Similarly, the tendency of water to wet a solid surface preferentially and displace oil is a function of both the contact angle 8 and the interfacial tcnsion Sow. The precise function depends on the geometry of the surface being wetted. Displacement of oil by water on a flat solid surface is governed by one function of e and So-; displacement from capillary spaces between fibers is governed by a different function. The mathematical theory has been discussed in the literature (5,6 ) . I n displacement of oil from textile fabrics by water, the tendency is measured by a capillary-wetting function, the displacement pressure. Dwo,
=
so,
cos 0
(2 1
Substituting Equation 1 into Equation 2, it is seen that Dme = S a o -
Saw
The cotton cloth used was Nashua hfills Indian Head fabric without permanent finish. This was cleaned by xashing for 20 minutes in a household washing machine with a 0.1% solution of Triton X-100 a t 50" C. It was then given 6 rinses with t a p water a t 50" C. and agitated for 5 minutes during each rinse. T h e washed cloth was pressed with a clean hand-iron, hung up for 3 days in a dust-free room maintained at 24" C. and 50% relative humidity, and then cut into 0.75 X 0.50-inch swatches. These swatches were stored in the constant-humidity room until used. T h e salts and detergents were weighed out int.0 250-ml. beakers. Into each beaker 150 ml. of preheated distilled water were run t o dissolve the solids. Then 50 nil. of preheated solvent were run slowly down the side of each beaker to form an upper laxer. Beakers were placed in a thermostatic bath maintained at 49 =t 1 C. Ordinarily, readings were first t,aken 5 minutes after adding the solvent, which was 10 minutes after dissolving the solids in water. To make a determination, a swatch was t,aken by its edge with metal forceps and held below t h e surface of the solvent in the beaker for 3 seconds. It was t,hen allowed to fall in such a way t h a t it arrived in a horizontal position a t the water-solvent interface. Timing was commenced when it reached the interface. I n running a series, the various solutions were run sequentially using one swatch to each beaker. The series was repeated a second and a third time. Figures listed in the tables are all averages for three determinations. If a swatch had not sunk after 120 seconds, its sinking time was recorded as >120. If the three determinat,ions on a solution yielded one or two values of > 120 and the others under 120, the value 120 was used for the values greater than 120, and the average thus calculated was prefixed with a > sign. After the solutions had remained for 1 hour a t 50" C., three more series of readings were taken. To indicate the degree of precision which can be expected, average deviations from the mean are noted for average values, except those derived from > 120 readings.
(31
The interfacial tensions and contact angle referred to in Equations l to 3 are those for mutually saturated surfaces. Equation 3 provides a picture of the process. Preferential wetting depends on a tug of war between the force, S,,, which tends to cause water to spread over the fibers, and So,, which tends to cause oil to spread over them. However, Equation 2 is much more useful because So, and 8 can be measured while S,, and S,, cannot. Attempting to specify preferential wetting in terms of the angle e alone ( 1 , 8) can result in misleading conclusions. That is analogous to specifying wetting of solids by a liquid in air in terms of contact angle alone instead of by a function of contact angle and surface tension of the liquid. It should be noted t.hat
TABLEI. AVERAGESINKINGTIME FOR 0.75 X 0.50-IXCH COTTON-CLOTH SWATCHES FROM S o v a s o ~NO. 5 INTO 0.5% QOI~UTIONS OF SALTSIN WATERAT 49' C. 7 -
Sodium metasilicate Sodium hydroxide Trisodium phosphate Sodium carbonate Sodium tripolyphosphate Tetrasodium pyrophosphate Sodium hexametaphosphate Sodium tetraphosphate Sodium ohloride SⅈnL sulfate Water
Solution Agc GO-70 min. 10-15 min. A v . Sinking Time, SCG.->120 >lo5 >110 >103 >120 183 >98 > 68 8.5 * 1 6 * 1.3 7.8 * 2 10.3 * 4 . 8 6.7 * 1 . 8 5.3 * 2 . 8 6.8 * 2.2 4 * 0.3 > 120 >120 >120 >120 > 120 >120
December 1949
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
Each simultaneous group of experiments is listed in a separate table. I n all except the last group, the solvent used was Sovasol No. 5 , a hydrocarbon solvent of the Stoddard solvent type. In the last group, a medium-viscosity mineral oil, Carnation oil, wa? used.
2799
TABLE 11. SURFACE AND INTERFACIAL TENSIONS (Corrected values for detergents unbuilt and built with sodium sulfate as determined in distilled water solution a t 25' C. with du Nouy interfacial tensiometer)
DISCUSSION
1
II
s
The alkaline salts listed in Table I fall into two sharply distinct classes. The molecularly dehydrated phosphates all show sinking times of a few seconds. The other salts, both alkaline and neutral, show sinking times of over 60 seconds. Inert salts can improve detergent performance and surfaceactive behavior in general, when present in a solution of a soap or synthetic detergent. One mechanism, by both neutral and alkaline salts, is increasing the tendency of the surface-active agent to form micelles and to concentrate at interfaces. Another mechanism, by alkaline salts only, is neutralizing fatty acids present in the soil, thus forming soap at oil-water interfaces. Most synthetic detergents are comparatively poor in washing cotton fabrics but may be improved materially by adding alkaline salts. Molecularly dehydrated phosphates such as tetrasodium pyrophosphate and sodium tripolyphosphate are more effective than other alkaline salts in improving the detergent action of synthetic agents on cottons, particularly a t low concentrations of detergent; this despite the fact that they are not strongly alkaline (16). I n a broad sense, a builder is defined as any added material which improves the effectiveness of a detergent. A narrower definition, frequently implied in the literature, is an added material, ordinarily an inorganic salt, which reduces the concentration of detergent needed to obtain a given degree of surface activity in solution. A widely accepted interpretation is that the builder, by reducing the solubility of the surface-active agent, promotes sorption or concentration of the agent a t interfaces. Building of anion-active agents in this narrower sense depends primarily on the cation of the building salt. The effect is similar t o flocculation as governed by the Schulze-Hardy rule (18, 14). Thus all sodium compounds should show approximately equal effects when present in concentrations which give equal sodium ion activities. Nonionic agents are not ordinarily susceptible to building in this manner. This is demonstrated by data in Table 11. Interfacial tension was measured against a solution of 0.1% of oleic acid in benzene (11). That the anion of the builder is of limited importance in building an anion-active agent is demonstrated by the data in Table 111. Here benzene without oleic acid was used in determining interfacial tension. Since some of the builders are alkaline, oleic acid would complicate interpretation of results by forming soap and thus lowering interfacial tension. Concentrations of builders were chosen t o yield the same sodium ion concentration. The effects of the different builders on interfacial tension are approximately the same. I n lowering surface tension, the two neutral salts appear to be slightly more effective than the alkaline salts. Molecularly dehydrated phosphates have been demonstrated t o be unusually effective builders for synthetic detergents on cottons. This effectiveness has held for nonionic as well as anionactive detergents. That is not building in the narrower sense. Rather, since it is not accompanied by any specific alteration of interfacial tension a t oil-water or water-air interfaces, it is reasonable t o assume that it is caused by action of the polyphosphate ions a t the fiber surface. The data in Tables IV, V, and VI indicate t h a t a synthetic detergent of the alkyl aryl sulfonate type increases the sinking-time values of alkaline salt solutions. This is not surprising. I n Equation 2, if e is already small, due t o the action of alkaline salt, so that cosine e is near 1, the surface-active agent will not affect its value greatly. However, it will reduce So, radically by concentrating a t the oil-water interface. Consequently the wetting force, D,,,,is reduced and displacement of oil is hindered. That is analogous to wetting agents lowering surface tension and
Anion-active Nacconol N R S F a Duponol M E b Anion-active Xa Anion-active Y a Anion-active ZQ Nonionic Triton NEC Nonionio Xd
Surface Tension, Dynes/Cm. 0.05% detergent 0.05% plus 0.15% detergent NatSOa
Interfacial Tension against 0.1% Solution of Oleic Acid i n Benzene, Dynes/Cm. 0 05T" d&e-rgeht 0.05% plus 0.15% detergent NaL3Od
36.1 35.8 34.9 32.4 33.7
31.4 32.4 31.4 30.4 30.4
3.6 2.9 10.7 6.5 6.0
2.1 2.2 2.8 2.3 2 ~-R
30.0 27.7
29.4 28.4
15.9 18.4
16 5 17.9
Over 90% active sodium alkyl aryl sulfonate Over 90% active sodium lauryl sulfate. 30% active, no salts. d 100% active, no salts. a
b
C
TABLE 111. SURFACE AND INTERFACIAL TENSIONS (Corrected values fo? 0.02% solution of Nacoonol N R S F unbuilt and built with various inorganic salts as determined in distilled water solution a t 25O C. with du Noily interfacial tensiometer) ConcentraSurface Interfacial Tension tion of Tension against Benzene, Builder Buildern, 7% Dynea/Ch. Dynes/Cm. N"7W .. RQ R R 7. So>i;m chloride 0: 20 32.4 2.3 Sodium sulfate 0.24 31.3 1.8 Trisodium phosphate 0.19 33.6 2.2 Sodium carbonate 0.18 34.2 2.5 Tetrasodium pyrophosphate 0.23 34.5 2.6 Sodium tripolyphosphate 0.29 34.0 2.4
-.
a
These concentrations furnish equal amounts of sodium ions.
TABLE Iv. AVERAGESINKING TIMEFOR 0.75 x 0.50-INCH COTTON-CLOTH SWATCHES FROM SOVASOL No. 5 INTO NACCONOL OR
SALT-NACCONOL SOLUTIONS IN WATERAT 49" C.
Solution Age 10-15 min. 60-75 min. ----Av. Sinking Time, Set.----.
Nacoonol N R 0.2%, plus Sodium melasilicate 0.2% Trisodium phosphate, 0.2% Tetrasodium Pyrophosphate, 0.2% Sodium tetraohomhate. 0.2% Nacconol N R , 6.1%' Nacconol NR, 0.2% Nacconol NR, 0.4%
>120 >120 > 72 64 A 37 >120 > 120 >120
>120 >120 29 t 3 > 56 >120
thereby hindering rather than aiding penetration of water into capillaries of materials which show a low contact angle against water, as exemplified by glass capillaries. Wetting agents are helpful in promoting wetting of surfaces with high contact angles but not of surfaces with low ones. The functions of organic detergent in washing fabrics are three in number. One is t o serve as a conventional wetting agent in order t o permit the solution to penetrate into the capillaries and crevices between fibers over the oily surface, before displacement of oil and soil commences. The second is to suspend the soil which has been detached from the fibers, so that it may be rinsed away, The third is to remove oil and soil by emulsification, by rupture of oil-oil bonds, without necessarily wetting the fiber or displacing the oily film completely. However, it apears that in washing cottons with an alkyl aryl sulfonate built with molecularly dehydrated phosphates, the organic detergent does not favor preferential wetting of the fibers by the solution, and displacement of oil. Instead it hinders such action. Further studies are planned t o determine whether other organic detergents behave similarly and to determine their preferential wetting behavior a t low concentrations in the absence of builders. The foregoing discussion has assumed that the solvent used resembled oils in preferential wetting behavior. The logical nest,
2800
I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
TABLEV.
AVERAGESIXKINGTIXE FOR 0.75 X 0.50-INCH COTTON-CLOTH SWATCHES FROM S O V A S o L 5 INTO AQUEOUS SOL7JTlOh’s AT 49 C. Solution Age 10-15 rnin. 60-70 niin. r----Av. Sinking Time, Sec.--Necconol N Rphosphate, , O.Z%, plusO.Zyo >120 >120 Trisodium Sodium carbonate, 0.2% > 103 >120 Sodjum tripolyphosphate, 0.2% 29 * 6 53 * 15 Sodium hexametaphosphate 524 .3 * =% 4 2.4 8 . 7 >592 . 1 Sodium tetraphosphate, 0.2% Tetrasodium pyrophosphate, 0.2% 5 . 5 ;t 3 . 0 18 + 5 Tallow chip soap >120 >120 Sodium oleate >120 >120
TABLE VI. AVERAGESINKINGTIUE FOR 0.75 X 0.50-INCH c ~ ~sWATCIIES ~ FROM ~ soVAsoL ~ N -~ 5. INTO c A~~~~~~ ~ ~ SOLUTIONS AT 49” C. Solution Age . 10-15 min. 60-70 min. -Av. Sinking Time, Sec.Tetrasodium pyrophosphate, 0.27, Plus iu‘acconol N R , 0% Plus Xacconol N R , 0.01% Plus Nacconol ?R, 0.05% Plus Nacconol h R , 0.2% Trisodium phosphate, 0.2% Plus Nacconol N R , 0% Plus Naoconol N R ,0.01% Plus Nacconol N R , 0.05% Plus Nacconol N H , 0.2% Carboxymethylcellulose, low viscosity, 0.2 % Plus Nacconol N R , 0% Plus Nacconol N R , 0.2% Potassium ferrocyanide, 0.5% Potassium ferrocyanide, 0.2% Plus Nacconol N R , 0.2%
77
*
*
4.8 28
31
* i
3.8 16
>96 >120
>72 >97
>120 >120 >120 > 120
> 120 >120 > 120 > 120
6.8 * 1.6 >120 30 * 2 ,,
. ., .. .
>I20
Vol. 41, No. 12
show t,hat both compounds favored preferential wetting by water and to degrees not unlike molecularly dehydrated phosphates. The procedure as set up at present is suitable only for showing marked differences in preferential wetting. It is not nearly so precise as could be desired. The major known variables are: Uniformity of cloth. This includes uniformity in the chemical state of the fiber surfaces and uniformity of weave. Cleanness of cloth surfaces. To obtain fiber surfaces free of contamination a more thorough cleaning technique than described may prove necessarv. Humidity eonditcon of clot’h. Prewetting of cloth with solvent. The longer t,he cloth is kept in solvent before bringing to the interface, the greater is the sinking time. I t may be desirable to presoak the cloth for some hours Or days in before using. Manner ~ of~dropping cloth. If the cloth hits the interface at an angle it will submerge partially at the st,art. Sinking time may then be much l o o low. Physical form of cloth. A perfectly flat cloth is desirable. Differences in manner or force of pressing cause results to vary, by altering the fiber packing. Age and manner of preparation of solutions. Micellar or hydrolytic changes in solutions, as well as gradual concentration of surface-active agents at interfaces, alter sinking values, dcpending on the history of the solution-solvent system. These variables are familiar causes of variation in determination of surface and interiacial tensions by the common techniques.
8 * l >120
Owing to the inherent nature of the test, determinations need to be set up as group experiments, comparing relative rather than absolut,e results.
. . . . ... ,
SUMMARY
. . . . . . .. >120
By the two-phase wetting technique described, molecularly dehydrated phosphates show sinking times of a few seconds;. other salts commonly used as builders show times of over 60, TABLE~’11. AVERAGESIXKING T I ~ FOR ~ E 0.75 x 0 . 5 0 - 1 ~ ~ ~ COTTON-CLOTH SWATCHES F R O M -hfINERAL OIL I N T O AQUEOUS seconds. This effect, is associated with a multivalent negative SOLCTIONS AT 49” C. ion. Solution Age___ Mathematical predict,ion that addit,ion of synthetic detergents 10-15 min. 60-70 min. t, o molecularly dchydrated phosphates may increase the sinking - . - - A ~ . sinking ~ iset,-~ ~ Sodium metasilicate, 0.5% >120 >120 time is confirmed. These results correlate with unusually good Trisodium phosphate, 0.5% >I20 >120 detergency of the synthetic detergents on cottoiis when the synTetrasodium pyrophosphate, 0.5% 25 * 3 30 =t 2 . 5 Sodium hexametaphosphate, 0.5% 12 i 3 . 3 16 2.5 thetic detergents are highly built with molecularly dehydrated Nacconol NR, 0.2% >120 >120 phosphates. The results are attributed t o effects a t the fiber Sodium oleate, 0.2% 88 * 20 >ll6 Trisodium phosphate, 0.2% surface rather t,han a t t h r oil-water interface. Plus Naoconol N R , 0.2% Tetrasodium pyrophosphate, 0.2% Plus Nacconol N R , 0.2%
81
>lo1
45
5
38
17
*
8
LITERATURE CITED
(1) Adam, N. K., in “Wetting and Detergency” (Symposium of International Society of Leather Trades’ Chemists, British
step of running similar tests using such oils is shown in Table VII, the results having been obtained with a mineral oil. The magnitudes of the sinking time values are different, but the same relations hold. The complicating effect Of having saponifiable oils and free fatty acids present has thus far been avoided, but such oils will be investigated to parallel natural-soil oils more closely. I n that work it is planned to take into account recent work on the oils in nat’uralsoil ( 2 ) . I n Table VI, the effect of increasing proportions of Nacconol in a tetrasodium pyrophosphate solution is shown. As expected, sinking time increases. It is, however, not unlikely that very small proportions of surface-active agent added to water without alkaline salt would decrease sinking time. It seems probable that the rapid sinking times achieved with the molecularly dehydrated phosphates is associated with the large negative charges on the anions produced by these compounds. The mechanism postulated is sorption of the anions which leads to a strong negative charge on the fibers, with consequent attraction of the electropositive water solution. If it is correct, other compounds which furnished polyvalent, anions should behave similarly. The sinking times of potassium ferrocyanide and sodium carboxymethylcelIulose solutions in Table VI
Section), 2nd ed., pp. 53-6, New York, Chemical Publishing Co., Inc., 1939. (2) Brown, C. B., Research ( L o n d o n ) , 1, 46-8 (1947). (3) Draves, c. z.7 and Clarkso11i R. G.7 Am. Dyestuff RePtr., 20, 201-8 (1931). (4) Forster, R. B., Uppal, J. S.,and l’enkataraman, K., J. &c. Dyers Colourists, 54, 465-72 (1938) ( 5 ) Harkins, W. D., and Boyd, G . E., J . Chem. P h . ,10,342-56 (1942). (6) Osterhof, H. J., and Bartell, F. E., J.P h y s . Chem., 34,1399-1411 (1930). (7) Reich, I., and Snell, F. D., IND. ENG.CHEW,40, 1233-7 (1948). ( 8 ) Robinsori, C., i n “Wetting and Detergency” (Symposium of Iriternational Society of Leather Trades’ Chemists, British Section), 2nd ed., pp. 137-51, New York, Chemical Publishing Co., Inc., 1939. (9) Seyferkh‘,H., and Morgan, 0. M., Am. Dyestuf Reptr., 27, 52532 (1938). (lo) Sncll, F. D.9 I N D . EI-x+* CHEhf.9 24, 76-80 (1932) (11) I b i d , pp, 1051-7. I
(12) Ibid.. 25, 162-5 (1933).
i13) Ibid., pp. 1240-6. (14) I b i d . , 35, 107-17 (1943). (15) Sne117F. D . i Inc.,
data.
RECEIVED January 4. 1949. Presented before the Di>ision of Colloid Chemistry a t the 116th hIeeting of the AMERICAN CHEMICAL SOCIETY, Atlantic City, N, J.
