INDUSTRIAL A N D ENGINEERING CHEMISTRY
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VoI. 22, No. 9
11-Soap and Oil as Soaking Agents Ralph Hart and George W. Searell Y.
HARTPRODUCTS CORPORATION, 1440 BROADWAY, XEWYORK,N. Y., A N D KAHN& FELDMAN, INC., BROOKLYN, N.
CCORDING to Seem (1) the materials used for soaking raw silk are many and include the following: oliveoil soap; neat’s-foot or olive oil; alkali carbonates; proprietory oils composed of neat’s-foot and mineral oils ; partly saponified neat’s-foot or olive oil; sulfonated castor, neat’s-foot, olive, or coconut oil; and sulfonated oils blended with mineral oil. The combination most often used, p y ticularly for soaking crepe (yarn of high twist), is an emulsion of neat’s-foot or olive oil in a solution of olive-oil soap. There is also a great divergence in the practice of soaking, even with the same formula, as well as in the apparatus employed. The need for standardizing the process has been voiced frequently in recent trade publications. I n this paper an attempt is made along this line by presenting data on the process of soaking raw silk in an emulsion of neat’s-foot oil and soap as practiced in some plants.
Upper layer: Per cent of weight separated, based on combined layers. ................................... Neutral f a t based on upper layer, about.. . . . . . . . . Neutral f a t based on total neutral f a t in combined layers, about, , . . , , , , , , , , , , , . , , , , , , , , . . , , . Lower layer: Free fatty acid., . . . . . . . . . . . . . . . . . . . . . . . . . . . . F a t t y acid as s o a p . . . . . . . . . . . . . . . . . ~. . . . . . . . . . .
Experimental Procedure
Total f a t t y a c i d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neutral f a t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A
A bone-dry skein of silk was soaked overnight a t room temperature in exactly five times its weight of an emulsion composed of approximately 2.25 per cent anhydrous olive-oil soap and 3 per cent neat’s-foot oil, containing 2.6 per cent free fatty acid. The emulsion was prepared by adding the oil to the cooled soap solution and stirring rather vigorously for a few minutes. The wet skein was squeezed hard by hand and the excess combined with the rest of the liquor. The amount of liquor left in the silk after this treatment was approximately equal to hydro-extracting for 5 minutes a t 900 r. p. m. The emulsions before as well as after soaking were very unstable, breaking almost immediately and separating into a turbid soap layer and an upper rich creamy emulsion. The various layers, as well as the silk, were analyzed for free fatty acid, fatty acid as soap, and neutral fat. Rate of Separation The rate and ultimate separation of the liquor before soaking, determined in 100 cc. of the solution in a 7-inch graduate, is given in Table I. Practically all of the upper layer had risen in less than 1 hour, after which the layer became more concentrated in fat until a volume of 5 per cent was reached, when there was practically little further change upon prolonged standing. Table I-Separation
TIME Minutes 5
of U p p e r Layer before Soaking VOLUME VOLUXE UPPER LAYER TIME UPPER LAYER Hours Per cent Per cent 1 9 3 R 3 6 6 5.5 9 5.25 12 5 12 4.75
Analysis of Liquor and Silk The analyses of the different layers before and after soaking, as well as the soaked silk, are given in Table 11. UPPERLAYER-The separations after 24 hours before and after soaking were almost equal and amounted to about 5 per cent of the total weight. The upper layers contained 40 to 45 per cent neutral fat, or from 60 to 65 per cent of the total neutral fat in the mixtures. LOWERLAYER-The composition of the lower layer after soaking showed similar characteristics as already reported
in Part I of this paper-namely, the development of free fatty acid and the decrease in concentration of soap and fatty acid in the liquor. It will also be noted that the lower layer was richer in neutral fat after soaking than before. This may be due to the better emulsification of the oil either by the acid soap or the small amount of sericin in solution. Table 11-Composition of Liquor and Soaked Silk BEFORE ARTER SOAKING SOAKING
Per cenl
Per cent
4.95 45.0
40.0
75.0
60.0
.
Total fatty m a t t e r . . . . . . . . . . . . . . . . . . . . . . . . . . Combined layers:
0.10 2.06 2.16
0.83 -2.99
...................... .....................
0.10 2.1G
..................... ....................
2.20 3.10
Total f a t t y m a t t e r . . . . . . . . . . . . . . . . . . . . . . . . . . . Soaked silk: Free fatty acid.. . . . ...................... F a t t y acid as s o a p . . . . . . . . . . . . . . . . . . . . . . . . . .
5.30
Total f a t t y a c i d . . . . . . . . . . . . . . . . . . . . . . . . . Neutral f a t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Total f a t t y matter.. . . . . . . . . . . . . . . . . . . . . . . Correction for alkali in fatty matter. . . . . . . . Total f a t t y matter, corrected. . . . . . . . . . . . . . Total take-up (includes degumming factor). . . . . . . Absorption of liquor: Liquor absorbed, based on dry silk.. . . . . . . . . . . . . absorbed, based on original liquor
.
,
............................
5.02
0.63
1.21 _1.84 1.29 3.13 0.65
1.25 -
1.90
_-3.43 5.33
1.55 1.95 3.50 3.05 6.55 0.13 -6.6s
6.62 136.0 27.2
Depos-it of soakidg ingredients: Fatty acid on silk, free and as soap, based on f a t t y
(w)
liquor ...................... Total fatty matter on silk, based on total fatty (6.68 X 100) , , , , matter in original liquor 5.30 X 5 Fatty acid adsorbed, free and as soap, based on dry raw silk (3.50 136 X 0.019). . . . . . . . . . . . . . ~
-
31.8
19.7 25.2 0.92
COMBINEDLAYER-The concentration of the neutral fat in the combined layers was even somewhat greater after soaking than before, indicating probably no adsorption of neutral fat by the silk. SOAKEDSILK-Although the soaking was made in a practically neutral emulsion, the fatty matter extracted from the silk consisted of almost equal parts free fatty acids and soap, or 1.55 and 1.95 per cent, respectively. Yarn intended for the hosiery or knitting trade is often treated with a soaking preparation to which excess alkali carbonate has been added. This leaves the silk neutral and less likely to rust the needles. It is also well to consider the effect of the free fatty acids on the process of boiling-off or degumming. As free fatty acids they are probably detrimental to the process because of the soap consumed to keep them emulsified, but when converted into soap by means of alkali they actually help the degumming. Since the average quantity of anhydrous soap used in boiling off is about 20 per cent of the weight of the silk, the saving in soap may be
INDUSTRIAL AND ENGINEERING CHEMISTRY
September, 1930
more than 10 per cent; for the saving is not only in the soap formed by the neutralization of the fatty acids but also in the soap otherwise required to keep them in suspension. Spparently the amount of degumming was negligible, since the ‘(take-up,” amounting to 6.22 per cent, which is the difference between the bone-dry weights of the silk before and after soaking and which therefore takes into account the degumming factor, was only slightly below total fatty matter of 6.68 per cent extracted from the silk. The neutral fat seems to interfere with the free adsorption by the silk, since the amount of soap and fatty acids adsorbed was less than when soaked in a straight soap solution. Other data given in Table I1 are the absorption of liquor and the deposit of soaking ingredients on the silk, in each case calculated on the dry raw silk and the original liquor. Uneven Soaking
The instability of the emulsion and the ultimate concentration of neutral fat in a comparatively narrow layer would lead
985
one to suspect that the deposit of fat on the silk may not be uniform throughout. This was actually found to be the case. Two skeins of silk soaked in the same batch, one on the bottom of the tub and the other near the surface, were analyzed for total fatty matter. The bottom skein contained 9.68 per cent, compared with 14.90 per cent for the top skein. On the other hand, except for the silk close to the surface, the absorption of fatty matter in commercial soakings were found to be fairly uniform and close to the amount calculated from the liquor retained by the silk. Rapid penetration of the liquor and entanglement of the oil among the fibers may account for the comparatively uniform results obtained in practice. Nevertheless, the need of an emulsion of greater stability, at the same time retaining the lubricating and penetrating properties and pH value of the present formulas, is obvious. Literature Cited (1) Seem, “Raw Silk Properties, etc.,” p. 115 (1927).
The Problem of Establishing the Identity and Purity of a Hydrocarbon Obtained from Petroleum’.’*3 Edward W. Washburn BUREAUOF
STANDARDS, WASHINGTON,
D . C.
HE various handbooks
The evidence in support of the identity and purity Evidence of Purity and monographs dealof most of the hydrocarbons reported as having been ing with the chemistry isolated from petroleum is inadequate. Suitable tests Before attempting to idenand technology of petroleum for purity and evidence for identity are described and tify a fraction as someparticuusually contain r a t h e r discussed and a procedure is suggested. It is recomlar hydrocarbon, it is neceslengthy lists of hydrocarbons mended that at least the five properties-refractive sary-xcept perhaps in the index, density, boiling point, freezing point, and case of the lower hydrocarwhich, the author states, have been isolated from petroleum. halogenation behavior-be reported on all petroleum bons, where the number of i?len, however, one examines fractions for which identification is claimed. possibilities is so small and the properties are so well known the evidence for the identification and purity of these supposed hydrocarbons, it becomes and so widely different that both purity and identity can be espainfully apparent that in the majority of cases this evidence is tablished by comparison of properties alone-to prove that the either utterly worthless or, when properly interpreted, proves fraction is substantially a single substance, not a mixture. that the material is not the hydrocarbon claimed. It may in- Since in general it cannot be assumed that, even if pure, the deed be and probably is true that all the reported hydrocarbons, fraction is a known hydrocarbon for which reliable physical as well as a great number of others, actually do occur in and data are on record, it is clear that the criteria for purity should, can be obtained from some one or more petroleums, but this as far as possible, be independent of the availability or nonprobability is one thing and actual proof of the isolation, by availability of corresponding data for the pure hydrocarbons. fractionation, of a given hydrocarbon from a given petroleum The most generally used criteria for purity are those which is something quite different. The purpose of this paper is depend upon (a) vaporizing or condensing behavior and (b) to discuss the nature of the evidence which must, be obtained crystallizing or melting behavior. (a) VAPORIZING OR CONDENSING REHAVIOR AS A TESTFOR before identity and purity can be considered to be established ’PuRITY-This test for purity is usually applied by determining with reasonable certainty. the distillation range (boiling-point range) under Constant 1 Received May 28, 1930. Presented before the Division of Petroleum Chemistry at the 79th Meeting of the American Chemical Society, Atlanta, barometric pressure Or by determining the initial and final Ga., May 28, 1930. vapor pressures during an isothermal vaporization or conPublication approved by the Director of the Bureau of Standards densation, Neither of these procedures is very sensitive. of the U. S. Department of Commerce. To obtain a greater sensitivity the test may be conducted as The author disclaims all originality for the discussion herewith fOllOWS: presented. The principles involved and the methods and technic suggested
T
have been used and described many times in the literature. They have not, however, always been observed and utilized by workers in the field of petroleum chemistry, and it is hoped that this discussion may be helpful to investigators in this field. The principles and methods here described are those which are being employed in an investigation on “The Separation, Identification, and Determination of the Chemical Constituents of Commercial Petroleum Fractions,” listed as Project 6 of American Petroleum Institute Research. Financial assistance in this work has been received from a research fund ,of the American Petroleum Institute donated by John D. Rockefeller. This fund is being administered by the institute with the cooperation of the Central Petroleum Committee of the National Research Council.
Using an efficient fractionating apparatus carry out a complete vaporization fractionation of the whole sample under conditions which avoid all danger of cracking. Set aside the first fraction obtained as soon as it amounts to a few cubic centimeters; or, if the size of the total sample warrants it, discard this small initial distillate and collect and preserve the next small fraction which comes over. Continue the fractionation until only a few cubic centimeters of residue remain and set this aside also; or, if preferred, reject this small residue and collect and set aside the last small fraction of distillate. For these two small fractions (initial and final) determine
