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Electrode potential and polarographic studies have been made on solutions of zirconium and hafnium ions in molten normalLiCl‐normalKCl eutectic at 450°–550°C. Anodic dissolution of Zr at 450°C yielded Zr(IV), but at 550°C, chiefly Zr(II). Only Hf (IV) was observed over this range. Apparent standard electrode potentials were (mole fraction scale, Pt(II)/Pt(0) reference) normalZr)(II/normalZr)(0;−1.77normalv at 550°C normalZr)(IV/normalZr)(0;−1.86normalv at 450°C normalHf)(IV/normalHf)(0;−1.88normalv at 450°C;−1.92normalv at 550°C

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The system lithium nitrate-water has been investigated by thermal analysis and by X-ray powder diffraction studies. No trace of the hemihydrate reported by Donnan and Burt was found. The X-ray powder diffraction pattern of LiN03.3HzO has been obtained.The equilibrium diagram of the system ethanol-water shows an inflection a t -30' C., corresponding to 40 weight per cent ethanol. This is almost certainly a true peritectic point. The formula of the hydrate formed (if there is one) is uncertain but it may be C?H,OH,5HzO.The system lithium nitrate-ethanol could only be studied in dilute solution (of lithium nitrate) and a t temperatures near room temperature, because of high viscosity and extreme supercooling. No evidence for the existence of a solid alcoholate has been obtained.The system lithium nitrate -ethanol -water has been investigated in the form of a series of pseudobinary systems containing water and alcohol ill fixed ratios. No solid alcoholate of lithium nitrate has been found in solutions containing less than 50 weight per cent ethanol. The investigation could not be pushed beyond this alcohol content because of high viscosity and supercooling. INTRODUCTIONThis study was undertaken as a result of work on the conductance of lithium nitrate in a mixed solvent of water and ethanol (1). We think that, as the alcohol content of such a solvent is increased, the solvation of the lithium ion must change, either progressively or suddenly, from a water solvation t o an alcohol solvation, with consequent increase in the effective diameter of the lithium ion. \Ve hoped t o support this view by the isolation of a solid crystalline alcoholate of lithium nitrate, analogous to the water compound LiN03.3H20, but it appears, a s a result of the work here described, that such an alcoholate does not exist, or a t least that it cannot be isolated. Despite the failure of the original aim of this work, much interesting information has resulted, particularly that relating to the important system ethanol-water.The system lithium nitrate -ethanol -water involves the three binary systems lithium nitrate -water, ethanol-water, and lithium nitrate -ethanol. The latter system has not previously been investigated but the first two have been the subjects of several researches.The system LiN0,-H20 was first studied in detail by Donnan and Burt (2). They reported the existence of a congruently melting trihydrate and of a hemihydrate, which decomposed into anhydrous salt and solution a t 61.1' C. Campbell and Kartzmark (3) repeated the dilatometric experiments of Donnan and Burt but were unable to find any evidence for the existence of the supposed hemihydrate; neither did hemihydrate appear in their isothermal study a t 25' C.The system ethanol-water has attracted the attention of many worlcers but much uncertainty has always surrounded it. This system is well ltnown for its anomalous physical behavior, and the large deviations from ideality shown by its physical properties have often been put fonvard as evidence of compound for...

The mechanism of the reduction of Cr(III) in molten FLINAK was studied using cyclic voltammetry and chronopotentiometry over a temperature range of 612°–983°C and a Cr(III) concentration of 0.07 to 0.13 mol/l. Two reduction and two oxidation steps were observed, but extensive differences in the electrochemistry were seen over the measured temperature range. Cr(III) is reduced to Cr(II) followed by a two‐electron reduction of Cr(II) to Cr metal and both reduction processes are quasi‐reversible. The product of the first reduction process is soluble at 983°C, but is insoluble at lower temperatures.

In vivo clinical evaluations of human mammary tissue, including normal, dysplastic, and neoplastic breasts, were initiated using the FONAR method of nuclear magnetic resonance (NMR) imaging. Spin-lattice relaxation times (T1) were determined and correlated with other diagnostic modalities including mammography, xeroradiography, and sonography. Normal breasts and breasts with extensive fatty replacement were found to have the lowest T1 values, whereas T1 values of malignant tissue were elevated. T1 values for mammary dysplasia extended over a wide range, and NMR images exhibited lower proton density than normal tissue. In several patients with severely dysplastic breasts, T1 values overlapped those from patients with documented breast neoplasms. Markedly elevated T1 values were obtained from fluid-filled cysts that were well beyond the range of malignancy.

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The communication skills of chemistry students, among others, are generally maintained to be deficient. ~o s e n t h d refers t o 16 papers in this Journal1 between 1975 and 1987 that are coneeried with writing and the need for its improvement. At Rensselaer, concrete steps have been taken to address this problem a t the Institute level, and this paper describes how we have incorporated Institute requirements into our chemistrv oromam.The gist of the Institute's requirement is that aU students take two "writine intensive" courses, one of which is in the major. ~c c o r d i n g to Institute guidelines, "a course in the maior becomes writine intensive by virtue of its success a t heiping students to uGderstand and master discipline-and profession-specific uses of writing as modes of thinking and communicating." In general, faculty, in writing intensive courses, are expected to provide students with more than two opportunities to write, to make this writing integral to the actual work of the course and relevant to students' writing in the giving of grades, and t o provide clear and consistent feedback and timely commentary to help students imnrove. . -As a means of supporting this approach, graduate students in the Deoartment of Laneuaee. Literature. and Com-" " .munication have been made available as "writing consultants" to students and faculty in these courses. Tmically these writing consultants begin by constructing a desiiiptive analvsis of the features of student performance on the first writing assignment and meeting with faculty to determine which of these features are appropriate or inappropriate for the specific field. The writing consultants then make these criteria available to students and use them to give students comments on drafts of major writing assignments. Students then revise their work and turn it in for evaluation by the denartment. -~ ~ .~~~~~~~~~ ~ The chemistry laboratory program seemed t o us to be the loeical lace to stress communication throueh this writine-~ ~ . intensive requirement. The chemistry ma&rs1 laboratoryconsists of a seouence of four lareelv integrated laboratow courses in the sophomore and junior in which most experiments extend over multiple periods. Some labs have been graded on the basis of aresults summary (sample calculations, answers to questions, brief discussion of specific points,etc.), while ochers have required written formal reports. We have felt that a small number of reports requiring significant effort could be given more attention b4 both students and faculty than could formal reports on every experiment. These reports are modeled on journal styles and are expected to focus on the chemistry of the experiment, not on the students' perception of its educational value. Faculty grading these reports have been concerned most ' Rosenthal, L. C. J. Chem. Educ. 11987, 64, gQG998. strongly with correct chemistry hut have attempted to stress good writing and proper format as well. However, faculty have often felt uncomfortable in evaluating writing style (except for...