[WHEELER] CUBICAL EXPANSION OF VITREOUS QUART/ 143 



Crystalline quartz parallel to axis 7 • 5xl0- 6 * 



" perpendicular to axis 13-5x10-° 

 fused quartz, or fused silica 0-4 x 10- 6 



Owing to the extreme smallness of the expansion of the amor- 

 phous quartz, and also to the fact that small specimens were often 

 more easily obtainable, most observers during this period adopted 

 some modification of Fizeau's 2 interference method. 



Dr. Kaye's summary of the work is shown graphically in Fig. II., 

 which is reproduced from his paper, in which values of (l t - 1 )/1 

 given by or deduced from the results of the various observers, are 

 plotted against the temperature (t). At moderate temperatures, he 

 quotes the work of Chappuis 3 (1903), of Scheel 4 (1903,1907) and of 

 Randall 5 (1910); at low temperatures, that of Scheel 6 (1907) and Dor- 

 sey * (1907); and at high temperatures, that of Le Chatlier 8 (1900), 

 Callendar » (1901), Holborn and Henning 10 (1903), Minchin u (1907), 

 Randall 12 (1910). The combined results of these observers with the 

 exception of those of Minchin, in whose work certain errors had been 

 found, are shown in Fig .II. The excellent agreement of the results, 

 especially over the range 0° to 1,000°C, is noticeable. 



Dr. Kaye 1 makes some interesting remarks concerning the 

 "change points" exhibited by the curve of Fig. 2. One of these 

 points occurs at about 1,000°C. which is, as Dr. Kaye remarks, in 

 agreement with the conclusion of Day and Shepard 2 that above about 

 1,000°C. fused silica devitrifies into crystalline tridymite which ap- 

 pears to be the stable phase above this temperature. 



It might be noted that, in the light of more recent investiga- 

 tion, the dotted part of Dr. Kaye's curve does not appear to represent 

 the truth. For example, in 1912 Callendar 3 describes a specimen of 

 vitreous silica, which he examined, as having "a well-marked flat or 

 change-point, in the curve near 1,000°C, above which the slope 



1 Benoit, Trav. et Mém. du Bur. Intl. I, 1881; Scheel, Ann. der Phys. 9, pp. 

 837-853, 1902; Randall, Phys. Rev. 20, pp. 10-37, 1905. 



2 Ann. der Chem. et des Phys. (4) 2, pp. 143-185, 1864; Ibid (4) 8, pp. 335-361, 

 1866. Comptes Rendus 58 pp. 923-932, 1864; Ibid 62, pp. 1133-1148, 1866. 



3 Procès Verbaux, Intl. Comm. des Poids et Mesures, p. 75, 1903. 



4 Verh. d. D. Phys. Ges. 5, pp. 119-123, 1903; 



" " 9, pp. 718-721, 1907. 



5 Phys. Rev. 30, pp. 216-235, 1910. 



6 Verh. d. D. Phys. Ges. 9, pp. 3-23, 718-721, 1907. 



7 Phys. Rev. 25, pp. 88-102, 1907. 



8 Loc. cit. 



9 Chem. News<?J, pp. 151-152, 1901. 



10 Ann. der. Phys. 10, pp. 446-448, 1903. 



11 Phys. Rev. 24, pp. 1-21, 1907. 



12 Loc.cit 



13 Loc. cit. 



14 Amer. Jour. Sci. (4) 22, p. 298, 1906. 



16 Proc. Phys. Soc. London 24, p. 195, 1912. 



