DAY AND SOSMAN '. EXPANSION COEFFICIENT OF GKAPHITE 287 



*Compt. rend. 68: 1125-1131. 1869. Pogg. Ann. 138:26-31. 1869. Fizeau's 

 values are for a, the true coefficient; the mean coefficient from 0° has been calcu- 

 lated from the original values. 



t Ann. Phys. 13: 307-318. 1881. 



t Proc. Roy. Soc. 70: 237-246. 1902. 



For pencil-graphite, Muraoka found the value 0.95 X 10 ~ 6 

 But as this is a mixture containing only 52 per cent of graphite, 

 it is hardly comparable with data on pure materials. 



The wide range of these data is striking, especially when taken 

 in comparison with the expansion coefficients of other forms of 

 carbon, and of carbon compounds. It will be seen from the table 

 below that from the expansion coefficient of diamond to that of 

 anthracite we have an increase of forty-fold. 



*Pogg. Ann. 128: 583. 1866. 

 t Compt. rend. 68: 1125-1131. 



1869. 



t Landolt-Bornstein-Meyerhoffer Tab. p. 202. 

 third of cubical. 



Figures are mean linear, or one- 



A rough parallelism is immediately evident between the tem- 

 peratures of formation and the expansion coefficients of the differ- 

 ent varieties of carbon in the two tables above. The highest coef- 

 ficient is possessed by bituminous coal, which is followed closely 

 by anthracite. The Cumberland (Borrowdale, England) graph- 



