



48 PHYSICAL PROPERTIES AND COMPOSITION 



T 



abnormally on fall of temperature, being for ^ = 0-639, 



less than a third (0-409) of its original value (1-411), whilst 

 that of ether is approximately constant. This, however, is 

 the behaviour to be expected as a result of molecular 

 doubling, since the originally monomolecular liquid then 

 contains double-molecules, as a component, and these lower 

 the vapour pressure. This fact obviously agrees with that 

 already mentioned (p. 26), that saturated ethyl alcohol 

 vapour, on cooling, occupies an abnormally great volume. 



3. TEMPEKATUKE RELATIONS. 

 A. The Critical Coefficient. 



In what precedes we found among the critical data partly 

 additive, partly colligative, properties. The former, as to 

 the volume, which is quadruple the volume at the absolute 

 zero, the latter, as to the volume compared with the theo- 

 retical volume under the critical pressure and temperature. 



Starting from the empirical expression of the latter rela- 

 tion (p. 23), 



P k V k _ R 



T k "3-7' 

 or 



F "57'X; 



it appears that the additive properties of the volume must 

 also be traceable in the quotient 



T*. 



From the theoretical relation deduced on p. 21 



and F* = 



we get the same result, since 



