Properties And Compostion Of Glass Determined By Flow Measurements.

Glass subjected to localised heating shows a permanent deformation, due to to viscous flow, which can be determined by measuring the birefringence value. The latter varies as a function of heating-time and temp., and also depends on the comp. It is of interest, therefore, to consider the possibility of using birefringence measurements as a rapid means of assessing, without delicate equipment and at a relatively low temps., the comp. of glass specimens.