﻿416 On the Thermal Expansion of Mercury. 



The tab^e shows not only the contradiction between the 

 results of Callendar and Moss and the direct measurements 

 of: Chappuis, to which Callendar and Moss have already 

 called attention, but shows also that the same contradiction 

 is present with respect to Chnppuis' observations by the 

 indirect method, and likewise with all the measurements of 

 the Reichsanstalt, all of which are in excellent agreement. 



How this contradiction is to be explained must for the 

 present remain undetermined. Still, so long as the results 

 of Callendar and Moss are not confirmed from other sources 

 it is scarcely allowable to use the comprehensive tables which 

 they have given at the end of their publication, instead of 

 those tnbles for the expansion of mercury between 0° and 

 100° which have been used up to the present. 



7. Just lately Harlow *, at the suggestion of Callendar, has 

 determined the cubical expansion of fused silica by the 

 weight thermometer method, using mercury as the tbermo- 

 metric substance. He began the work with the same doubt 

 w r hich Callendar and Moss have raised, namely, whether it is 

 allowable, with a claim to great accuracy, to calculate the 

 cubical expansion of a bodv from the linear by the multi- 

 plication by 3. As the result of his observations on three 

 dilatometers Harlow gives the mean cubical expansion 

 coefficient of fused silica between 0° and 100° as 0'998 . lO" . 

 On division by 3 one would obtain from this 0*33 . 10 -6 as 

 the linear expansion coefficient. This value is in contra- 

 diction with all other known determinations for the linear 

 expansion of fused quartz between 0° and 100° that have 

 been obtained up to this time. 



The following values for this coefficient were found by : — 



Chappuis (1903 f) for a small cylinder of 10 mm. 



diameter prepared by himself 0'50 . 10 ~° 



Scheel (1903 %) tor a small cylinder 3*7 mm. in 



diameter from W. C. Heraus ,. 0'47 . 10~ 6 



Scheel (1903 %) for a small cylinder 7 mm. in 



diameter from W. C. Heraus 0'46 . lO" 6 



Scheel (1907 § ) for a ring-shaped body from the 



firm Carl Zeiss, Jena 0*51 . 10~ G 



Holborn and Henning (1903 ||) for a rod 2*9 mm. 



in diameter and 0*52 m. long from Heraus 



(mean expansion coefficient between 0° and 



250°) 0-48. 10- 6 



* F. X Harlow, Proe. Phvs. Soc. London, xxiv. pp. 30-30 (1912). 



t P. Chappuis, Verh. d. Naturf. Ges. Basel, xvi. pp. 173-183 (1903). 



% K. Scheel, Verh, d. D. Phys. Ges. v. pp. 119-123 (1903). 



§ K. Scheel, ibid. ix. pp. 718-721 (1907). 



j| L. Holhorn and F. Henning, Ann. d. Phys. (4) x. pp. 44G- 448 (1903). 



