Surface of Finely-Ground Silica

Abstract

THE existence of a highly soluble surface layer on quartz particles, foreshadowed by the results of Briscoe et al.¹, and of King², has been demonstrated in our laboratory, and the properties of the layer studied in considerable detail³. All siliceous dusts examined possessed initially a high-solubility layer which is apparently not discrete, but blends smoothly into the less soluble core. It is removed by various solvents, a borate buffer (pH 7.5) being principally studied; and it is dispersed by this buffer mainly in the form of somewhat flocculent colloidal silica, the less soluble core afterwards yielding, more slowly, clear solutions of silica. In view of the importance widely attached to the ‘solubility theory’ in studies on silicosis, it is clearly of interest to determine whether the high-solubility layer on inhaled siliceous dusts plays any significant physiological part; and experiments on this problem have been initiated.