42 ELISHA MITCHELL SCIENTIFIC JOURNAL 



pie proportions, and form an introduction to two-component 

 systems. 



Under two-component one-phase systems we have mixtures 

 of indifferent gases, dissociation of g-ases, mixtures of liquids 

 with and without formation of compounds, solid solutions. 

 With solid and vapor we can have a dissociating- solid com- 

 pound, or a compound existing- in the vapor only, such as the 

 oxides of carbon in equilibrium with carbon, or nickel car- 

 bonyl. Under solution and vapor we g-et Henry's law, the 

 law of van't Hoff and Raoult, the phenomena of osmotic 

 pressure, all boiling-point phenoma and the theory of electro- 

 lytic dissociation. The other cases of two-phase equilibria 

 involve solubility under pressure. With three phases we have 

 the dissociation pressures of compounds such as hydrated 

 salts, calcium carbonate, etc.; solubility relations, freezing- 

 point determinations, etc.; while with four phases we g-et the 

 characteristic properties of the quadruple point. 



With three components we g-et more of the characteristic 

 reactions of chemistry. The reaction between carbon monox- 

 ide and water belong-s under the heading- of vapor phase; the 

 formation of esters in organic chemistry is referred to systems 

 involving a liquid phase; the solubility of gases in solutions 

 belong-s under two phases, liquid and vapor. With three com- 

 ponents and three phases, we get the precipitation of a salt 

 by another salt or 03- a liquid, the conditions of existence of 

 double salts, the blast-furnace reactions, the reduction of 

 chlorides or sulphides by hydrog-en, the facts in reg-ard to 

 shaking out, many of the facts concerning dyeing, fractional 

 crystallization, occlusion, theory of indicators, etc. 



With four components we g-et the solubility chang-es with 

 two salts having no ion in common, fractional precipitation 

 and also many cases of fractional crystallization. A very 

 large number of chemical reactions involve only four compon- 

 ents and therefore come in here. 



It will probably seem as though I have laid more stress on 

 physical chemistry than on inorganic chemistry. This is how- 



