Density of Water with the Temperature. 101 



working up experimental data, may also have a certain 

 theoretical significance, inasmuch as it may assist in explain- 

 ing the general law of the expansion of liquids *. For all 

 liquids except water the rate of change of the density with 



ds 

 the temperature (i. e. the differential coefficient -y-) varies but 



etc 



little, either rising or falling slightly with considerable varia- 

 tions of temperature ; for example : — 





Amyl alcohol. 



Sulphuric acid 

 (93ip.c). 



Phosphorus 

 tri bromide. 



Mercury. 



7 S ° = 



0-8248 



1-8525 



2-92311 



13-5956 



** 0°.., 



. -0-00076 



-0-00106 



-0-00244 



-0-002447 



„ 25° ... 



. -0-00077 



-0-00102 



-000245 



-0002439 



„ 50° .., 



. -000080 



-0-00099 



-0-00245 



-0002431 



,, 100° ... 



-0-00094 



-0-00092 



-000246 



-0-002415 



According to 



Kopp 

 (1855). 



Kremers 

 (1863). 



Thorpe 



(1880). 



Regnault. 



In the case of water, on the other hand, the differential 



ds 

 coefficient — not only changes its sign at 4°, but in general 



varies with extraordinary rapidity, even (judging from Hirn's 

 data, 1867) at temperatures far removed from 0°, above 

 100°:— 



10* 



ds 



dt 



0°. 



25°. 



50°. 



100°. 



160°. 



200°. 



+6 



-25 



-45 



-72 



-100 



-120 



Although I do not desire here to touch upon the question 

 of a first approximation towards the general law of the ex- 

 pansion of liquids, I consider it necessary to state that the 



* In the Journal of the Russian Physico-Chem. Soc. for 1884 (and also 

 in the Journal of the Chem. Soc. London, 1884), I stated that the ex- 

 pansion of liquids may be approximately expressed (at a point far 

 removed from their passage into another state and within the range of 

 the ordinary accuracy of determinations) by an equation of the form 

 St=S (l—kt) ; and although in various quarters doubts were enter- 

 tained as to the generality of such a law (especially by Avenarius and 

 Grimaldi), on the other hand, not less weighty proofs of its applicability 

 were brought forward (notably by Thorpe and Rlicker, Kraiewicz and 

 Konovalofr) ; so that the question of a general law for the expansion of 

 liquids must be considered as having just entered upon its first phases 

 of historical development. Just as when elaborating 1113' first article 

 (Journal of the Russ. Physico-Chem. Soc. 1884, p. 7), I then considered 

 the question of the expansion of water as unique, and as requiring special 

 determination, so now I maintain that the working out of this problem 

 will advance the very idea of the general law of the expansion 01 liquids. 

 I trust to return to this subject shortly. 



