The Determination of Alkalis in Silicates With Special Reference to High‐alumina Refractories*

This investigation pertains to the detailed study of two methods used to determine alkalis in silicates. The work was prompted through the difficulty of obtaining complete decomposition of high‐alumina refractory materials by the usual procedure. It was found that high‐alumina materials may be decomposed by the J. Lawrence Smith procedure with a single fusion, provided this is conducted at approximately 1200°C. The second procedure has to do with the decomposition of the sample with a mixture of nitric, sulfuric, and hydrofluoric acids. In this method, magnesia is eliminated by precipitation with 8‐hydroxyquinoline and the alkalis are weighed as sulfates. Experimental data are given pertaining to these procedures when used for the analysis of several types of materials.