230 GOLD Iisr SCTETSrCE AND IN INDUSTEY. 



gaseous or even of the liquid molecule, even when their cohesive forces 

 have been weakened or overcome by separation. 



// the energy employed in this sejMnvtioii. is not intnnsic to the 

 solute molecule then it must in some way have been imparted by the 

 solvent molecides. It therefore becomes important to compare the 

 energy endowment of one set of molecules with that of the other. 



Comjoared with other solids, ice at is freezing point has ver}^ little 

 hardness or tenacity ; the cohesion of its molecules has been much 

 relaxed by the great absorption of heat energy between the absolute 

 zero and the freezing point. If an average specific heat of O'o over 

 the wdiole range be assumed, the heat absorption of one gram amounts 

 to 136 -5 calories. In the transition to the liquid state at 0° a further 

 absorption of 71) calories takes place, so that a gram of liquid Avater 

 at the freezing point contains the heat energy of 215 -r) calories. The 

 fact that water has the high vapor pressure of 4*6 millimeters of 

 mercury at the freezing point is probably a result of this enormous 

 store of energy. As a liquid, therefore, it is natural to expect that its 

 molecules will exhibit efl'ects proportionate to this great store of 

 energy. This expectation appears to be realized when we consider 

 not only its properties as the universal solvent, but its osmotic and 

 diffusive energy in solutions in which it is the solvent. 



To complete the comparison it is only necessary to calculate the 

 heat energy of gold at 0°. Taking its specific heat as 0-032, a gram 

 of gold at 0° contains 8 '7 calories. A gram molecule, therefore, con- 

 tains in round numbers 1,700 calories as compared with 3,880 calories 

 in a gram molecule of water. 



Taking into consideration not only this greater store of energy, 

 but also the much smaller cohesive force of water as compared with 

 the majority of solid solutes, there can be no doubt that the active 

 role in aqueous solutions of this type must be assigned to the solvent, 

 not to the solute molecules. 



This leads to the important conclusion that the energy of solution, 

 of diffusion, and of osmosis is due, not to the imaginary gaseous en- 

 ergy of the solute, but to the actual liquid, energy of the solvent 

 molecules. When this conclusion is reached a new physical explana- 

 tion of these phenomena is in our hands, and we are relieved from the 

 strain to the imagination involved in the application of the gas theory 

 to solutions of nonvolatile solids. 



This transference of the active role to the solvent molecules does 

 not in any way affect the well-established conclusions based on the 

 laws of thermo-dynamics as to the energy relations in these phe- 

 nomena, for it has always been recognized that these conclusions have 

 reference to the average conditions prevailing in large collections of 

 relatively minute units. Wherever the gas analogy has appeared to 

 hold it has not necessarily involved more than this, that the observed 



