THE ARGUMENT 257 



and the several departments of physics, the 

 colloids and the ions of hydrogen and hydroxyl 

 remain to be mentioned. It has been shown 

 that the properties of water are exceptionally 

 favorable to the existence and stability of 

 colloidal systems ; also that the properties of 

 carbonic acid result in automatic regulation 

 of the concentration of hydrogen and hydroxyl 

 ions in the ocean and in the organism. 



So far, then, as it is possible to judge by 

 telling over the departments of physical 

 science, our examination of physical and chem- 

 ical properties has not been incomplete. 



This conclusion may be further tested with 

 the help of the ideas which underlie Willard 

 Gibbs's " Phase Rule." 1 According to this rule, 

 the condition of equilibrium in any material 

 system depends upon the number of its com- 

 ponents, the number of its phases, temperature, 

 pressure, and, in general, the concentrations 

 of all the components. Without entering 

 upon an explanation of the exact mathemat- 

 ical notions which determine the meaning 

 of the terms " component " and " phase " it 

 will here suffice to say that in general the 

 number of components increases as the num- 

 ber of separate chemical individuals increases, 



1 See, for instance, Findlay, "The Phase Rule and its 

 Applications." London, 1911, 3d ed. 



