THERMODYNAMIC AL SYSTEM OF GIBBS 



141 



Table V gives a comparison of the osmotic pressures of a 

 solution of cane sugar containing 1 gram molecule in 1000 grams 

 solution, as calculated by equation (185), using the vapor pres- 

 sure data of Perman and Downes,* with the direct determi- 

 nations of Morse, t 



TABLE V 

 Calculated and Observed Osmotic Pressures op Sucrose Solutions 



VIII. Conditions Relating to the Possible Formation of Masses 

 Unlike Any Previously ExistingJ 



24. Conditions under Which New Bodies May Be Formed. 

 So far, the only variations which have been considered possible 

 in applying the criteria of equihbrium are those involving 

 infinitesimal variations of the composition or state of the masses 

 originally present. The conditions of equihbrium so obtained 

 are obviously necessary for equihbrium but they are not always 

 sufficient, for an infinitesimal variation of the system may also 

 result in the formation of bodies entirely different from those 

 originally present, and in order to discover whether the original 

 state is one of equilibrium it is necessary to ascertain if the 

 criteria of equilibrium are also satisfied for variations of this 

 kind. 



Gibbs defines a new part as one which cannot be regarded as 



* Trans. Faraday Soc, 23, 95 (1927). The value used in the calculation 

 at 30° is obtained from the work of Berkeley, Hartley and Burton 

 (loc. cit.). 



t Osmotic Pressure of Aqueous Solutions, Carnegie Institution, Wash- 

 ington. Publ. No. 198 (1914). 



t Gibbs, I, 70-79. 



