( 821 ) 



jiiiv (loiiltt llui( the soliihililv lines will ^ive Süiiietliiiig' ;i.s repi-esouted 

 hy ■•<ii\(j^it^ and the donldc sail is Uuniid l(» be decomposed by 

 absolnte ak*oli(d with separation of silver nitrate. 



From the preceding it is obvious that the tbllowin,L>- eqnilibria 

 occur in the ([uatei-nai'y system: 



L + AgNOs of whicli L is represeniod by the surface: srr^s^ 



L + NHiN0;5 „ „ „ „ , n n n Q P Pi Qi 



L + AgNHi(N03)2 , , „ , „ , , . rqq^r^ 



L + Ag NO3 + Ag NH, (N03)2 , „ „ , „ „ , curve : r /•, 



L + Nn,N03 + AgNn,(N03), „ , „ „ „ , , „ qq. 



Oil looking at these e(pnlibria several (juestions arise one of which 

 I will mention. If, for instance w^e know that in the ternary system 

 water, silver nitrate, ammonium nitrate, of wdiich both salts are 

 aidiydrous, an anhydrous double salt occurs at 30° we may ask 

 ourselves wdiat equilibria will occur if the water is substituted by 

 another solvent such as aqueous or absolute alcohol. 



It is impracticalde to answer this cpiestion in its eidirety ; if, however, 

 we ai'gue that no solid phases are formed which crystallise with the 

 new solvent it becomes a fairly easy one. As a rule we can demon- 

 strate that the same three saturation lines \vill occur also in the new 

 solvent so that a solution saturated with the two components or 

 solutions saturated with another double salt camiot be formed. 



Therefoi'e, although the same double salt must appear in both 

 solvents, its behaviour in regard to the two pure solvents, may 

 however, be (piite different and various cases may occur; it may, 

 for instance be soluble in both solvents without decomposition or it 

 may be that, as in the case mentioned, it is soluble in the one 

 solvent without and in the other with decomposition ; or it may 

 dissolve in both solvents with decomposition. In the latter event we 

 may meet with two more cases; it may be that the same component 

 is de])Osited from both solvents or it may be that one of the com- 

 ponents is deposited from the one and the other from the other solvent. 



Similar equilibria occur also at 30^ in the systems : 



Waaler — alcohol — silver nitrate — potassium nitrate 



and water — alcohol — benzoic acid — ammonium bezoate. 

 In the lirsl system occurs a double salt of silver nitrate and potassium 

 nitrate; in the latter, which is being investigated by Dr. 11. Filippo, 

 a combination of benzoic acid and ammonium benzoate is formed. 



