The preparation of nitrides of chromium has been studied in detail. Oxygen free samples of Cr1.000Nx, x ranging from 0.997 to 0.980, have been prepared by equilibrating at temperatures from 850 to 1048 °C in one atmosphere pressure of nitrogen. Results of the temperature dependences of expansivity, lattice parameters, magnetic susceptibility and electrical resistivity of CrN of various compositions are reported. The antiferromagnetic → paramagnetic transformation in CrN exhibits temperature hysteresis and is shown to be a transformation of the first kind. The transformation temperature of Cr1.000N0.997 is 286 °K.

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The standard deviation in the absorbance at zero concentration is experimentally determined for ten elements in an airacetylene flame. The contribution of various noise sources to the total standard deviation is determined and the dominant source at the detection limit is found to be photon noise, lamp flicker noise, or flame transmission noise.

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