554 On the Expansion of Water and Mercury. [Dec. 21, 



Calculating from the five series the coefficients of expansion of mercury, 

 using Kopp's water-expansion (taking the volume at 4=1), we find as 

 mean 



V<=Vo (1+0-0001 78*). 



In the following Table I give the values obtained by different observers 

 for the volumes occupied by water at different temperatures, the volume at 

 4 being taken equal to 1. 



TABLE II. 



Kopp, Despretz, and Pierre used the same method for their determi- 

 nations that of determining the expansion of water in glass vessels (dilato- 

 meters). Hagen employed the weighing process, but at high temperatures 

 employed no special precautions to prevent the steam condensing on his fine 

 wire ; hence his values at 90 and 100 fall below mine. 



It will be seen from the foregoing Table that Kopp's values are lower 

 than the others ; and bearing in mind that the coefficient of expansion of 

 mercury, when deduced by means of these, falls below that obtained by 

 Regnault, but when deduced from Despretz's or my own agrees closely 

 with Regnault' 9, we are led to conclude that Kopp's values must be some- 

 what incorrect. 



* Pcgg. Ann. xcii. 42. t Ann. de Cbim. et de Phys. Ixx. (l re sr.) 1. 



} Ann. de Cbim. etde Phys.xiii. (3 mc ser.) 325. Calculated by Frankenheim, Pogg. 

 Ann. xcvi. 451. 



Abhandlungen d. k. Acacl. der Wisscnsch. zu Berlin, 18G5. 



