140 THE ROYAL SOCIETY OF CANADA 



Three decades later, in 1869, Gautier 1 succeeded in constructing 

 capillary tubes and spirals of fused quartz which he exhibited at the 

 Paris Exhibition in 1878. 



Then after the lapse of nearly two decades, in his search for a 

 suitable material for suspension fibres, Prof. C. V. Boys 2 again dis- 

 covered this material. To him is due the credit of having been the 

 first to recognize the great value of fused quartz. In 1889 3 , in lectur- 

 ing before the Royal Institution, Prof. Boys described his well-known 

 method for the production of exceedingly fine, uniform and strong 

 quartz fibres by means of a cross-bow and arrow, and demon- 

 strated the measurement of the Newtonian constant of gravitation 

 by means of an instrument no bigger than a galvanometer. So 

 fine was he able to produce these quartz suspensions that he could 

 detect the gravatational force between two No. 5 shot, and he even esti- 

 mated that a grain of quartz just large enough to be visible would 

 furnish material sufficient for 1000 miles of the finest fibre which he 

 produced. 



Boys' work was followed by the advances of Shenstone and others 

 until now the manufacture of fused silica apparatus, even of com- 

 plicated form, has been undertaken on a commercial scale. 



The combination in a single material of very many desirable phy- 

 sical properties has led to the use' of fused silica for many purposes. 

 It is highly refractory, — its melting point, which is not very definite, 

 being higher than that of platinum, though it softens appreciably 

 below 1,500°C. It possesses remarkable transparency, even for 

 very short wave-lengths. At high temperatures it is extremely 

 ductile, while at moderate temperatures, it possesses a hardness 

 greater than that of ordinary glass, and an almost perfect elasticity. 

 It is a very good electric insulator even in an atmosphere containing 

 much water vapour. The smallness of its thermal expansion and 

 thermal hysteresis together with its resulting ability to withstand 

 sudden changes of temperature 4 has led to its adoption as a desirable 

 material for accurate dilatometer bulbs and for standards of length. 



On the other hand, it becomes slightly permeable to hydrogen 6 and 

 helium 6 at about 900°C. Above this temperature it also devitrifies 

 with a gradual increase in length, accompanied probably by a slight 

 change in other properties. Though devitrification may take place 



I Comptes Rendus 130, p. 816, 1900. 



- Phil. Mag. (5) 23, pp. 489-499, 1887. 

 ; Nature to, pp. 247-251, 1889; Science 14, pp. 61-62, 1889. 

 4 Dufoui Comptes Rendus 130, pp. 1753-1751, 1900. 

 B Villard " " 130, pp. 1752-1753, 1900. 



II Sir William Crookes, Chem. News, 105, p. 205, 1912. 



