The article reviews some modern methods of analysis with special reference to instrument techniques. Direct reading emission spectroscopy. The glass sample is fused with Li2B4O7 and mixed with graphite. It is then subjected to a high voltage condensed spark, intensities of emission being recorded on a chart. Such intensities are readily convertable to wt.%oxide. X-ray spectroscopy. X-ray fluorescence has been used on silicate materials for such trace elements as S,Zn,Cd,Se,Zr,Ag,Au,As,Sb,Pb and Ti. polarography. This method is slower than those mentioned above since the glass sample must be dissolved. It is applicable to a large number of reducible ions and has been especially sucessfull in estimation of Cd,Zn and Pb. Flame photometry.In general this method is most readily applied to alkali and alkaline earth elements. Spectrophotometry. Many glass constituents including silica itself are now estimated by colorimetric processes involving finally a measurement of absorbence at the main emission wavelength. Radiochemical analysis. Due to its large absorption cross section for thermal neutrons boron can be estimated accurately in a borosilicate glass.
