1901.] Vitrified Quartz. 525 



WEEKLY EVENING MEETING, 

 Friday, March 8, 1901. 



Alexander Siemens, Esq., M. Inst. C. E., Vice-President, 

 in the Chair. 



W. A. Shenstone, Esq., F.R.S. 



Vitrified Quartz. 



Although the great improvements introduced into the art of glass 

 making by Abbe and Schott have led to such marked advances in 

 microscopy, thermometry, and in other departments during the last 

 quarter of a century, glass remains unsuitable for many of the 

 purposes to which we put it, and there is still a real need for some 

 plastic material more infusible, more insoluble, more fully trans- 

 parent, more elastic and more stable under changes of temperature 

 than glass. 



Such a substance exists in the form of vitrified quartz, or vitrified 

 silica, as I shall prefer to call it. 



Vitrified silica was made first in 1839 * by M. Gaudin, who spun 

 threads of it by hand and noticed their flexibility, made it into small 

 very hard pellets by dropping fused quartz into cold water, and 

 observed that it was inactive to polarised light.+ It was rediscovered 

 in 1869 by M. A. Gautier,| who made capillary tubes and spirals of 

 silica, and exhibited them at the Paris Exhibition in 1878, but who 

 failed to obtain larger objects even with the aid of the electric 

 furnace. Finally, it was discovered yet once again in 1889 by Pro- 

 fessor C. V. Boys, who used the torsion of " quartz fibres " for 

 measuring small forces, produced fine tubes and small bulbs from 

 vitrified silica, and who was the first to fully recognise the great 

 value of this remarkable substance. 



As all who are here to-night are not chemists, I may remind you 

 that quartz or rock crystal has for some time past been used by 

 spectacle makers and in the construction of optical instruments, and 

 that it is a form of oxide of silicon,§ a compound which is very familiar 

 in the forms of sand and flint. It is occasionally found in magnificent 

 masses, and our chief source of supply is Brazil, where it occurs in 

 large fragments like those on the table before us. 



Quartz itself exhibits many of the desirable qualities enumerated 



* Comptes Rendus, viii. 678, 711. 



t A more recent observation made by Professor S. P. Thompson confirms this. 



% Comptes Rendus, cxxx. 816. 



§ Silicon was discovered by Berzelius in 1823. 



