Section III., 1914 [139] Trans. R.S.C. 



The Cubical Expansion of Vitreous Quartz. 



By N. E. Wheeler, M. Sc. 



Lecturer in Physics, McGill University 



(Presented by Dr. H. T. Barnes, F.R.S.) 



(Read May 27, 1914). 



The measurement of the thermal expansion of vitreous quartz, 

 or fused silica, has been the subject of numerous investigations in 

 recent years. The importance of an accurate knowledge of its linear 

 coefficient has been recognized, especially in connection with its use 

 in thermometry, and in the construction of standards of length. 

 Recently, in connection with the careful determination of the co- 

 efficient of expansion of mercury, the question has arisen as to whether 

 the cubical expansion of a silica dilatometer bulb can, with sufficient 

 approximation, be calculated from its linear expansion measured 

 in one direction only. In view of these facts, and of the importance 

 of an accurate knowledge of the expansion coefficient of a suitable 

 standard liquid, a résumé of the more important papers dealing with 

 measurements of the expansion of fused quartz may perhaps be of 

 some general interest. 



I. HISTORICAL DEVELOPMENT. 



In 1901 in a lecture 1 before the members of the Royal Institu- 

 tion, W. A. Shenstone summarized much of the work which had, up 

 to that time, been done on fused quartz. As he pointed out, the manu- 

 facture of fused quartz dates back to 1839 when Gaudin 2 made 

 fine threads of quartz and noted their great strength which approxi- 

 mates that of steel. Gaudin also produced very hard small pellets 

 of fused quartz, by dropping the molten material into cold water, 

 and observed that in this form quartz is inactive to polarized light. 

 He attributed the permanently high viscosity, which renders possible 

 the production of remarkably fine and uniform fibres of quartz, to a 

 constancy of temperature produced by continual evaporation. 



1 Proc. Roy. Inst. 1901; Nature 64, pp. 65-67, 1901; Chem. News 83, pp. 205- 

 207, 1901. 



- Comptes Rendus 8, pp. 678-679, 711-713, 1839. 



