PURE BERYLLIUM OXIDE AS A REFRACTORY*

The development of a pure BeO refractory is described, using pure Be(OH)₂ as the starting material. The hydroxide is calcined at 1200° (low) to 1800°C. (high), depending on the crystal size desired. The calcine is ball milled wet in a steel mill and cast at pH 4.5 to 5.0, or the powder may be dried and mixed with 14% Carbowax 4000 added as a water solution for dry pressing at 20,000 to 30,000 lb. per sq. in. The pressed product is vitreous when fired at 1800°C. but is also volatile at that temperature.     

REACTION OF DIFFERENT CLAY MINERALS WITH SOME ORGANIC CATIONS*

Selected pure samples of kaolinite, illite, and montmorillonite were washed with 0.05 N HCl until free from replaceable bases, washed with water or methanol, and then reacted with sufficient KOH to saturate the exchange complex with K⁺ at pH 7. These K clays were given variable dosages of n-butylamine acetate, dodecylamine acetate, and ethyldimethyloctadecenylammonium bromide. The conclusions are as follows: (1) additions of amines or other organic cations in amounts less than equivalent to the base-exchange capacity of the clay are rather. completely adsorbed in base-exchange reactions; amounts of large organic cations added in excess of the base-exchange capacity of the clay tend to be adsorbed by a different reaction, probably dependent on the action of the van der Waals' forces; and (2) the ability of clays to absorb water is greatly reduced by treating the‘clays with certain compounds that furnish a large organic cation.     

SEMICONDUCTING CERAMIC MATERIALS*

The paper presents a brief résumé on the principles of electrical conductivity. Studies were made on compositions consisting mainly of oxides such as TiO₂, Fe₂O₃, FesO₄, ZrO₂, and others. The effects of composition on the electrical resistivity and its temperature coefficient of these semiconductors were investigated. The reduction of the oxides and its effect on electrical properties are described. Test results are correlated with the theory. The effect of activation energy on electrical properties of the semiconductors is also described.     

Determination of nitrogen in vegetable oils

Summary Hydrolysis with alcoholic hydrochloric acid quantitatively converts the nitrogen of crude soybean lecithin to a water-dispersible form. This alcoholic-acid hydrolysis also converts the nitrogen in large amounts of crude soybean oil to a water-dispersible form which can then be separated and digested with a minimum amount of sulfuric acid by the Kjeldahl procedure. With careful control of both reagents and blank determinations, as little as 0.1 mg. of nitrogen can be measured with a precision of about 10%. The details of the method are given and it is applied to a series of soybean oils after various treatments and to three kinds of salad oils. Presented by Dr. R. T. Milner of the Northern Regional Research Laboratory at the Spring Meeting of the American Oil Chemists' Society at New Orleans, Louisiana, May 20–22, 1947. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry. Agricultural Research Administration, U. S. Department of Agriculture.     

Factors affecting the reliability and precision of the spectroscopic determination of vitamin A

Summary By means of simple statistical methods the effects of technique, laboratory equipment, solvents, temperature, and instruments on the precision and accuracy of the determination of the extinction coefficient at 328 mμ of fish liver oils are outlined. Methyl, ethyl, propyl and butyl alcohols give successively lower E-values. As the temperature increases, Beckman spectrophotometers tend to give lower values. The cells used to hold the solutions to be measured need to be individually checked. No suitable standards for spectrophotometers are yet available, but potassium nitrate, potassium chromate, and Bureau of Standard glasses are useful. By careful observance of all the variations discussed the determination of the E-value may be made with considerable precision; the value of σ, the standard deviation, is 0.22%. Communication No. 82 from the Laboratories of Distillation Products, Inc.