July 15, 1932
INDUSTRIAL AND ENGINEERING CHEMISTRY
P€R CENT LAURIC ACID
263
44 per cent is present does the titer reach that on the mean line. At no place is the curve much above this line. As might be expected in view of the two preceding results, the addition of myristic acid (intermediate in position in the series between lauric and palmitic) to oleic, as shown in Figufe 5, gives a curve intermediate in form between that for lauric and palmitic acids. The titers of all mixtures are either on the line or above it, but there is no abrupt or great rise in any portion. That it is not possible to generalize about the behavior of the titer of mixtures of other acids until further data have been secured is apparent in view of the results obtained with these four acids. Mixtures of several other saturated acids, both with a less and with a greater number of carbon atoms, must be tried, and these acids in turn mixed with oleic. Another unsaturated acid-linoleic-present in corn oil, cottonseed oil, etc., as well as in the drying oils such as linseed, must be used before any attempt can be made to explain or predict the behavior of mixtures of naturally occurring oils and fats. LITERATURE CITED (1) American Chemical Society, Committee on Analysis of Commercial Fats and Oils. IND.EXQ.CHEM..18. 1346 (1926). (2) Francis,, Piper, and Malkin, Proc. Roy. SOL' (London), 'A128, 214-52 (1930). (3) Jennings, Q. W.,IND.ENQ.CHEM.,23, 413 (1931).
RECEIVED February 13, 1932.
FIGURE 4. TITERCURVEFOR MIXTURESOF OLEIC AND LAURICACIDS FIGURE5. TITERCURVEFOR MIXTURESOF OLEICAND MYRISTIC ACIDS (Figure 1) shows the depressing effect upon the titer of the addition of a higher titered material. This is similar to the effect upon the melting point observed in general when two materials similar chemically are mixed, but in the case of fatty acids no generalization can be made. The lowest point was reached with the mixture containing 30 per cent myristic acid. Mixtures of lauric and palmitic acids (Figure 2) give ti curve similar to Figure 1, but distinguished by the fact that palmitic acid, although having a higher titer, exerts a greater depressing effect upon the titer than does myristic acid. The low point, however, is reached at the mixture containing 30 per cent palmitic acid, just as 30 per cent myristic acid gave the low point in Figure 1. At approximately 60 per cent lauric acid the two curves cross each other and from there on the mixtures containing palmitic acid have the higher titer. At the point of greatest depression the titer of the mixture of lauric and palmitic acids is almost 15" C. below the "mean line." This is the line connecting the titers calculated arithmetically from the titers of the two pure acids involved (3). Mixtures of saturated acids with an unsaturated acid were tried next. Because its glyceride is a constituent of so many different naturally occurring oils and fats, oleic acid was selected. as the unsaturated acid. Figure 3 shows that the addition of a high titered acid (palmitic) raises the titer of the mixture even from the beginning, contrary to the effect observed in the two previous cases. The rise is abrupt and remarkable, reaching in one portion of the curve a point 16" C. above the mean line. Figure 4 shows the effect of mixing lauric acid with oleic. Instead of raising the titer of the mixtures, as did palmitic acid, it depresses it sharply a t the beginning, and not until
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