OF ANALYTICAL CONTROL FOR SILICA BRICK*

The prevalent use of silica brick has focused attention upon the need for control and improvement in quality. A review of the methods available reveals that many laboratory tests have been developed to avert expensive trial testing. It is significant, however, that the chemical knowledge of this product has lagged owing to (1) difficulty in sampling, (2) the tedious and time-consuming aspects of wet chemical methods, and (3) the consequent lack of knowledge of the deleterious effects of certain secondary constituents. One of the newer analytical tools is the spectrograph. A total-energy method has been developed to permit analysis of A1₂O₃, MgO, Fe₂O₃, CaO, Na₂O, TiO₂, K₂O, ZrO₂, MnO₂, and Li₂O. Thirty minutes are required for sample preparation and twenty-five minutes for the spectrographic process. Present accuracy is well within production limits. This method is also suitable for the analysis of glass sand.     

USE OF DOLOMITE AS AN AUXILIARY FLUX IN FLOOR TILE*

It is a recognized fact that dolomite is a valuable addition as an auxiliary flux in white ware bodies, and an excellent glaze ingredient providing another RO member which imparts low thermal expansion to the glaze. There is evidence that the addition of dolomite to sanitary-ware bodies has resulted in the lowering of the firing temperature without daunting or other ill effects. The present investigation involved a study of the use of dolomite in floor-tile bodies. A review of the literature showed that little or no work has been done in this field, and it was, therefore, necessary to follow somewhat closely investigations carried on in the vitreous sanitary ware and dinnerware fields to determine the optimum percentages of dolomite to be incorporated in the test batches. A typical floor-tile composition was taken as standard and dolomite was substituted in increasing amounts at the expense of the accepted flux. The purpose of this investigation is to ascertain if economies could be effected in lowering the firing temperature of the body by the addition of small amounts of a less costly constituent.