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We have found a linear relation between the transition temperature T, (in K) and the hydrogen-bond length R (in A) for tetragonal KHzPO4-type crystals, T, =2290(R -2.428), irrespective of whether the crystals are deuterated or undeuterated; this finding supplies negative evidence for the proton-tunneling mechanism in the phase transition. We deduce from this relation that the isotope effect in the initial pressure derivative of T"dT,/dp, reflects not the isotope effect in dT, /dR, so far regarded as supporting evidence of proton tunneling, but that in dR/dp. Some R and dR/dp values at T, are predicted.During the fifty years since the discovery of ferroelectric KH2PO4 (KDP), the problem of its phase transition and the large isotope eff'ect on such physical quantities as the transition temperature T, has been one of the most in-

Optically active 12-D-hydroxystearic acid (12-HSA) gives a thermally reversible organogel in several organic solvents. When a small amount of lecithin coexists with 12-HSA in organic solvents, the mechanical strength of the organogel is remarkably reduced. Interaction of lecithin with 12-HSA was studied by using infrared (IR) spectrometry, nuclear magnetic resonance (NMR) spectrometry, and scanning electron microscopy (SEM). Incorporating lecithin into 12-HSA reduced the absorbance in IR spectra, derived from hydrogen bonding between the hydroxyl groups and the carboxyl groups of 12-HSA molecules. Based on NMR measurements, the polar head groups of lecithin associate with the carboxyl groups of 12-HSA in a 1:1 molar ratio. SEM showed that the shape of the fibrous aggregates varied from a helically extended form to a spherical form. These results suggest that intermolecular 1:1 complexes were formed between lecithin and 12-HSA, which caused a structural change in the fibrous network in the 12-HSA organogel and consequently induced gel deformation. JAOCS 74, 491-495 (1997).

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