Surface of Finely-Ground Silica

Abstract

IN the course of silicosis research, a photographic-densitometric X-ray diffraction technique was developed for quantitative determinations of quartz, using magnesium oxide as internal standard, and recording line intensities in the range of 1.18–1.22 kX. With this technique it was found that carefully graded samples of quartz of less than 2 microns diameter gave lower intensities than larger fractions, although the fine samples showed only very slight indications of line broadening, and those only in the back-reflexion region. Numerical examples are given in Table 1, where the quartz ratings are expressed as percentages, taking the values for ungraded quartz from Madagascar as 100 per cent.