We report the characterization of Bi 2 Te 2 Se crystals obtained by the modified Bridgman and Bridgman-Stockbarger crystal growth techniques. X-ray diffraction study confirms an ordered SeTe distribution in the inner and outer chalcogen layers, respectively, with a small amount of mixing.The crystals displaying high resistivity (> 1 Ωcm) and low carrier concentration (∼ 5×10 16 /cm 3 ) at 4 K were found in the central region of the long Bridgman-Stockbarger crystal, which we attribute to very small differences in defect density along the length of the crystal rod. Analysis of the temperature dependent resistivities and Hall coefficients reveals the possible underlying origins of the donors and acceptors in this phase.

The horizontal flow of equal density oil‐water mixtures was investigated in a 1‐inch diameter laboratory pipeline. Oils of viscosities 6.29, 16.8 and 65.0 centipoise were used in the experiments. Flow patterns, holdup ratios and pressure gradients were investigated for a range of superficial oil velocity from 0.05 to 3.0 ft./sec. and a range of superficial water velocity from 0.1 to 3.5 ft./sec, with input oil‐water ratios ranging from 0.1 to 10.0. Similar series of flow patterns were observed for each oil and were found to be largely independent of the oil viscosity. At high oil‐water ratios oil formed the continuous phase and a water‐drops‐in‐oil regime was noted. As the oil‐water ratio was decreased the flow patterns concentric oil‐in‐water, oil‐slugs‐in‐water, oil‐bubbles‐in‐water and oil‐drops‐in‐water in which water was the continuous phase were observed. The most viscous oil did, however, exhibit anomalous behavior at low superficial water velocities and this is attributed to different interfacial properties. The pressure drops measured indicated that for a given oil flow rate the pressure gradient was reduced to a minimum by the addition of water provided that the oil was not in turbulent flow. Maximum pressure gradient reduction factors varied from 1.7 for the 6.29 centipoise viscosity oil to 10 for the 65.0 centipoise viscosity oil at input oil‐water ratios of 4.5 and 1.0 respectively.

Two‐phase gas‐liquid flow has been investigated in a 1‐inch internal diameter vertical tube coil containing two risers and a downcomer all connected by “U” bends. Flow pattern data were obtained in the three vertical tubes, each 17.30 ft. long, for five different air‐liquid systems at about 25 psia over flow ranges of 0–700 lbm air/min‐ft2 and 140–25300 lbm liquid/min‐ft2. Liquid phase viscosities ranged from 1 to 12 cp. A flow pattern classification with six regimes including coring‐bubble, bubbly‐slug, falling film, falling bubbly‐film, froth and annular flow regimes was established for downflow. Flow patterns in the bends were also classified. Data from the present investigation were used to formulate an empirical flow pattern graphical correlation for both upflow and downflow which is based upon the coordinates (Rv)1/2 and FrTP/A, where Rv is the delivered gas‐to‐liquid volume ratio, FrTP is the mixture Froude number, and A = μs/(SLσs3)1/4 in which μs, SL, σs are specific viscosity, specific density and specific surface tension respectively of the liquid with reference to water. The correlation was satisfactorily tested with independent literature data for upflow systems, including air‐water, steam‐water at various pressures, nitrogen‐mercury and air‐heptane, and data from flowing gas‐oil wells. No independent literature data appear to be available for testing the correlation for downflow systems, but it is anticipated that the correlation will prove to be generally applicable. The coring phenomenon in downward bubble flow was examined by means of high speed motion photography and is explained by the development of a lift force on a bubble.

Instances are cited in which the pressure gradient in an oil pipe line has been reduced by the injection of water into the pipeline. A general mathematical analysis is presented for two immiscible liquids flowing (1) in two layers between wide parallel plates, and (2) concentrically in a circular pipe. This will form a basis for the further study of oil‐water systems. Equations are derived relating the volumetric flow rates and the viscosities of the liquids with the pressure gradient. The conditions for which minimum pressure gradients and minimum power requirements occur were determined and these minimum values have been compared with known values for a pipeline flowing full with only a single liquid. The factors by which the pressure gradient and power requirement can be reduced are very large. For example, for an oil of viscosity 1,000 cp. flowing concentrically with water, the reduction factor is approximately 500. The pressure gradient reduction factors reported in the literature are compared with those predicted by theory, and conclusions are drawn regarding the position of the water phase.

We describe the crystal growth, crystal structure, and basic electrical properties of