﻿Thermal Expansion of Mercury. 



415 



expansion between 0° and 100° was obtained by the compa- 

 rison of thermometers. In this case too the values originating 

 from glass 16 m are placed in parentheses in Table II. 



5. Not only was the relative expansion of mercury deter- 

 mined by the use of the dilatometers mentioned in §4, but also 

 that of water in glass. Thus one obtains for each dilatometer 

 a value for the difference between the expansion for mercury 

 and that of water, in the calculation of which the expansion 

 of the glass is eliminated. 



The expansion of water between 0° and 1 00° has already been 

 determined by Thiesen * in the Reichsanstalt by the method 

 of balanced hydrostatic tubes. If now the value found by 

 him be combined with the above-mentioned dilatometer 

 observations, the specific volume of mercury at 100° expressed 

 in terms of that at 0° is obtained independent of the glass 

 expansion as follows : — 



From dilatometer 16 m No. 1 1-018 259 



„ No. 2 1-018 259 



verre dur No. 3. 1-018 254 



59 in 1-018 267 



Due to the excellent agreement of these separate deter- 

 minations much weight must be attached to the mean value 

 1-018 260. 



6. In the following Table II. the values for the expansion 

 of mercury obtained in the Bureau international and in the 

 Reichsanstalt are placed together in accordance to the fore- 

 going discussion and as variations from a mean value. 



" 



55 



55 



55 



55 



}t 



Table II. 



Temperature. 

 



Mean Value. 



Variations f 



iom the Mean Value XlO 6 . 





Chappuis 



direct. 



Chappius 

 indirect. 



Thiesen 



Scheel, a 



nd Sell. 



Callendar 



and 



Moss. 



16 m . 



59 m . 



Absolute 

 Thiesen. 



1-000 000 











(0) 











10 



1-001817 







-1 



(0) 



o 





-10 



20 



1-003 634 







_2 



(0) 



+ 2 





-IS 



30 



1-005 453 



_2 



_2 



(■+ 1) 



+ 3 





-24 



40 



1-007 273 



-3 



— 2 



(+ 1) 



+ 6 





-29 



100 



T018 257 



— 3 





(-25) 



-I 



+3 



- 52 



In the last column the observations of Callendar and Moss 

 are added in the same form. 



* Loc. cit. 



