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.     

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.     

A qualitative method for detecting surface active agents

A NEW METHOD is presented for the qualitative detection of small amounts of surface active agents which is generally applicable to all types, i.e. anionic, cationic, and non-ionic. This method is based on the solubilization in aqueous solution of certain oil soluble dyes, particularly Brilliant Oil Blue BMA. Presented at 20th annual fall meeting, American Oil Chemists' Society, Oct. 30 to Nov. 1, 1946, in Chicago, Ill.     

Abstracts

Journal of the American Oil Chemists' Society -     

DIELECTRIC PROPERTIES OF GLASSES AT ULTRA-HIGH FREQUENCIES AND THEIR RELATION TO COMPOSITION *

The dielectric constants and dielectric losses of 104 glasses of a wide range of compositions have been measured at 10-cm. and 3-cm. wave lengths by the resonating cavity method (3000 and 10,000 megacycles, respectively). By correlating the power-factor data with the compositions of these glasses, the authors propose a qualitative explanation of the mechanisms producing energy absorption and dielectric losses in the microwave range. These mechanisms are determined by the nature of the bonds joining atoms and ions in the randomly oriented atomic networks of glasses. The rigid and continuous networks of SiO₂ and B₂O₃ glasses are relatively transparent to centimeter wave lengths. Energy absorption and dielectric losses are low. Addition of network-modifying oxides yields glasses of greater energy absorption owing to the oscillation of the interstitial ions thus introduced. Increasing the content of any one of these ions in a glass results in higher losses while the coexistence of a variety of these ions generally results in lower losses. Alkali ions in glasses give rise to high losses, which increase as the number of ions present increases. Glasses containing a combination of alkalis show lower losses than the equivalent compositions with only one alkali. Divalent ions do not contribute as much to losses as alkalis, but high power factors are shown by glasses with high BaO or PbO contents. Using combinations of these oxides instead of only one, slight reductions in power factor are effected. Dissimilar interstitial ions interact in ultra-high frequency fields with the result that energy absorption is reduced. The losses of high-lead glasses are thus reduced by alkalis and, on the other hand, the presence of RO lowers the losses of glasses containing R₂O. Alumina increases the dielectric losses of glasses in much the same manner as other network modifiers.     

EFFECT OF COEFFICIENT OF EXPANSION OF GROUND- AND COVER-COAT ENAMELS ON THERMAL-SHOCK AND IMPACT RESISTANCE *

Four antimony cover-coat enamels, four fluoride cover-coat enamels, and four ground-coat enamels were formulated to give varying coefficients of expansion. The calculated values were 250, 275, 300, and 325 × 10^–7. The observed coefficients of expansion are included in the paper. The enamels were applied to standard 2-quart pudding pans and were tested for thermal shock and impact resistance using the standard methods of the Enameled Utensil Manufacturers’Council. The results show that thermal-shock resistance is controlled chiefly by the coefficient of expansion of the ground-coat and cover-coat enamels. The best results were obtained by using a cover-coat enamel with a low coefficient of expansion and a ground coat with a high coefficient of expansion. No conclusive evidence was found to indicate any effect of the coefficient of expansion of the ground- and cover-coat enamels on impact resistance. The solubility resistance and reflectance curves for the enamels are also included.