British Glass

Abstract Surface tension can markedly affect the growth or dissolution of small gas bubbles but, even when spherical symmetry is maintained and the interfacial concentration assumed constant, generally valid analytical solutions for the change of size with time cannot be obtained; approximations of limited validity are therefore often used. However, accurate and efficient methods for computing the diffusion-controlled growth or dissolution of spheres in such conditions have recently been developed; the results obtained when interfacial solute concentration is assumed constant have been published and validated by comparing them, where possible, with the equivalent analytical solutions. This paper extends that work to include the effects of a constant surface tension, for both Henry’s and Sievert’s laws. The numerical results are valid for as wide a range of parameters as is likely to be needed and are compared with the few analytical solutions available for particular cases. It is shown that, when surface tension is introduced, a complete description of the problem requires an additional saturation parameter as well as the dimensionless surface tension. It is also shown that Henry’s and Sievert’s laws can have very different effects on dissolving bubbles: when Sievert’s law applies a higher surface tension can increase time for a bubble to dissolve but this paradox can be resolved by examining the competing effects involved.

ABSTRACTSSNon‐destructive analyses are reported of a twelfth century stained glass panel from York Minster. The main conclusion from the results is that the observed differences in severity of corrosion between various glasses may be explained by variations in the proportions of potassium and calcium.

ONE of the most striking and least-understood aspects of refractory corrosion by molten glass is the relatively high rate of solution at the refractory-glass-gas interface, compared with that which occurs below the glass-level1,2. Any attempts to explain this phenomenon, or even measure it, are made exceedingly difficult by the complex nature of the materials involved3,4. This difficulty has been partially overcome by the use of single crystals of corundum as the refractory materials5,6, thus eliminating factors such as porosity, pore size, pore shape, texture, etc.