Robert D. Vold

A comparative study of the X-ray diffraction patterns and thermal transitions of metal soaps

SummaryX-ray diffraction patterns at room temperature for soaps of barium, calcium, and lithium were found to be characteristic for different soaps of the same cation. This is true not only for palmitates and stearates but also (with minor variations) for mixed soaps containing up to at least 50% oleate, for pure calcium oleate, and even for lithium 12-hydroxystearate.Soaps of the same cation in mixtures approximating the composition of natural tallow fatty acids appear to form mixed crystals. The succession of phases formed on heating shows strongly the influence of the oleate in the mixture.Calcium resinates appear to crystallize imperfectly but definitely with a “head to head” arrangment of the abietate radicals in contrast to the acids which give evidence of a head to tail arrangement.

Phase boundaries in ternary systems of sodium oleate, compared with other soaps

Summary1. The boundaries of isotropic solutions of sodium oleate containing salt have been determined over a series of temperatures. Prolonged heating in glass tubes alters sodium oleate solutions, rendering the soap less soluble.2. It is found that when sodium silicate replaces sodium chloride in the same percentage by weight the sodium oleate is not salted out, but tends on cooling to set to a clear jelly.3. The phase boundaries for soap solutions containing chloride have been assembled and recalculated to the same units for comparison with each other and with the results for soaps made from a few single commercial oils and fats. In spite of its solubility in water, sodium oleate is readily salted out by electrolytes.4. The effect of small amounts of salt such as are retained in commercial soap systems upon the boundaries of the strict binary phase diagram have been determined.