﻿1 hernial Expansion of Mercury. 413 



of his results can only be obtained when they have first 

 been considered in connexion with his investigation of the 

 expansion of water. And further, Callendar and Moss have 

 neglected to bring into the discussion the comprehensive and 

 pertinent results from the Reichsanstalt. 



2. Chappuis by means of the weight thermometer method, 

 and using a verre dur tube 1 metre long and 4 cm. in 

 diameter, determined the expansion of mercury between 0° 

 and 40°, and likewise in the neighbourhood of 100°, and the 

 linear expansion of the tube by the comparator (Direct 

 Method). 



Further, he calculated through the use of the value found 

 for 100° the course of the expansion between 0° and 100° by 

 comparing the verre dur thermometer with a hydrogen 

 thermometer (Indirect Method). The two methods give 

 values which agree well, as will be seen below in the 

 accompanying Table II. 



3. The measurements of Chappuis are supported also by 

 the fact that he determined by use of the same verre dur 

 dilatometer the thermal expansion for water * between 0° and 

 40° and at 100°, and still further in that he also obtained 

 the expansion of water between 0° and 40° by the use of a 

 platinum-iridium dilatometer, whose linear expansion was 

 obtained in the s-jme way as that for the hard glass dilato- 

 meter. 



The two investigations furnish excellent agreement, and 

 seem already to weaken the objection of Callendar and 

 Moss ; for it is, indeed, hardly plausible that the two vessels 

 of entirely different materials as used by Chappuis should 

 be to the same degree aeolotropic. Further, the Chappuis 

 values also agree excellently with the results which Thiesen, 

 !3cheel,and Diesselhorst f and later Thiesen J alone obtained 

 between 0° and 40° and likewise at 100° for water by use of 

 the balanced hydrostatic tubes. Besides this the Chappuis 

 values are also in agreement with the results obtained. in 

 1887 in the Bureau international by Thiesen § from the 

 weight of a quartz-kilogram in water. All of these values 

 relative to water are placed together in Table I. as variations 

 from a mean value. 



* P. Chappuis, Trav.etM6m.du Bureau international des Poids et 

 Mesures, xii : . L), 40pp., 1904 (1907). 



T M. Thiesen, K. Scheel und II. Diesselhorst, Wiss. Abh. d. Pln/s.- 

 Techn. Reichsanstalt, iii. pp. 1-70 (1900). 



t M. Thiesen, Ml. iv. pp. 1-32 (1904). 



§ Benoit, Trav. et Mem. du Bureau international des Poids et Mesures* 

 vii. p. 112 (1890). 



