The behaviour of crystals and lenses of fats on the surface of water—Part III. The effect of the polar group on the equilibrium pressure

The method of determining surface tension was that of measuring the force required to pull a platinum ring through the surface, as described in previous papers (1) (2). N/100 HCl solution was employed throughout. The organic compounds used were of such purity that the tension at equilibrium was, with certain exceptions to be noted later, independent of the amount of fat placed on the surface. At high temperatures some of the compounds studied, particularly the palmitates, were somewhat soluble. In these cases care is required to ensure that there is an excess of the ester present as a crystal or lens. This solubility did not, however, affect the equilibrium tension, the same values being obtained shortly after inoculating the surface and some hours later.