The solubilities of anhydrous CaSO, and CaS0,.2H?O in concentrated aqueous solutions of NaCl a t a series of temperatures-25" C, 30" C, 40" C, and 50" C, have been determined. I t was found that the transition temperature for the reaction which in pure water has a value of 42" C, is shifted progressively to lower temperatures with increasing NaCl concentration. It was also found that the variation of the transition temperature with S a c 1 concentration could be adequately represented by the equatiouwhere AG, AH, and AS are the Gibbs free etiergy, enthalpy, and entropy of the reaction and P O and Y are the vapor pressures of pure water and the solution respectively a t the absolute temperature T . INTRODUCTIONI t has long been known that the gypsum-anhydrite transition point is depressed by addition of strong electrolytes. However, it appears that no systematic study of this aspect of this system has ever been made, and only isolated experiments are reported in the literature (1).Since many naturally occurring gypsum deposits which are used as raw material for the commercial production of plaster of paris and building plaster are contaminated with various amounts of sodium chloride, it was decided to carry out a systematic study of the behavior of the system gypsum-anhydrite in the presence of varying amounts of sodium chloride. The results of such a study should afford a clearer understanding of the factors that govern the deposition of anhydrite or gypsum, as the case may be, from a slurry of hemihydrate (CaSO4.3H2O) and water, contaminated with NaCI. EXPERIMENTALThe salts used in this research, i.e. CaS04 anhyd., CaS04.2I-120, and NaCl, were all Fisher certified reagents of high purity. No recrystallization of the salts was attempted since it was felt that nothing would be gained by it in view of the high initial purity of the materials. An ignition analysis of CaS04.2H20 showed a loss in weight equal to the theoretically expected value of 20.8%. The anhydrous CaS04 was heated a t 900" C for 1 hour and subsequently kept in a desiccator a t a temperature of 60" C.Saturated solutions of gypsum and anhydrite were obtained as follows. Excess solid was added to an aqueous solution of sodium chloride of known con~position. The latter was contained in an all-hard-pyrex-glass solubility cell (Fig. I ) . The cell and contents were then immersed in a water bath the temperature of which was colltrolled by an electronic relay and was constant to within 0.05" C. The temperature of the water bath was read by means of a Beckmann thermometer. The latter was calibrated against a standard platinum resistance thermometer. The solutions were agitated for a t least 48 hours by means of a pyrex-glass stirrer. This time interval was found to be quite 'Manuscript receiaed Ape1 17, 1961.

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The deuteron fast Fourier transform (FFT) spectra of the ring deuterated nematogens para-azoxyanisole (PAA-d8) and p-methoxybenzylidene p-n-butylaniline (MBBA-d8) have been studied as a function of temperature. An interpretation of the spectra is presented. It is based on the assumption of nonequivalent deuterons, a twist angle φ between the planes of the benzene rings, and an asymmetry order parameter δ in addition to the usual nematic order parameter S. The temperature dependences of δ and φ have been obtained.

Plasma from patients with malignant and benign primary intracranial neoplasms and from healthy control subjects has been examined using proton (1H) and carbon-13 nuclear magnetic resonance (NMR) spectroscopy. Some features in the spectra of plasma from patients with malignant tumors differ significantly (p less than 0.01) from the corresponding features in the spectra of plasma from control subjects and from patients with benign tumors. The NMR spectral parameters vary consistently with the Kernohan grade of astrocytoma, which may suggest that they give a measure of tumor growth kinetics. The observed spectral differences are shown to be due to elevated levels of monounsaturated and polyunsaturated fatty acid residues in the plasma of cancer patients. It is proposed that these lipid residues arise from cell membranes shed from cells in growing tumors. The ability to follow tumor growth kinetics directly may be of considerable importance in elucidating the effects of primary intracranial neoplasm therapy.

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