On the Viscosity and the Allotropy of Glass

JSGT 1925 V09 T012-T024

Viscosity is certainly the most important of the properties of glass. On it depend all the methods of manipulation: blowing, moulding, drawing out. It is, on the other hand, the source of numerous difficulties in manufacture ; high viscosity resists the escape of gaseous bubbles from the body of the founding mass; it compels the fining to be carried out at a high temperature and to be much prolonged, which makes this operation very costly; further, it gives rise to chilling or tempering as it gets cold, a serious drawback which has to be corrected by a delicate annealing operation. The great interest which the study of this phenomenon presents will be readily understood, and it is surprising how inadequate are the data hitherto available in regard to it. The difficulty of the problem has long discouraged investigators; we are much indebted to Messrs Washburn & Shelton and to Mr English for the very important contributions which they have just made almost simultaneously to the study of this question.

Henry Le Chatelier (Translated from the French by Walter Butterworth)