HYDROLYSIS OF COMPOUNDS. 87 



clase, leucite, nephelite, spodumene, scapolite, laumontite, stilbite, chabazite, 

 heulandite, thomsonite. a If the theory of dissociation be true, this shows that 

 the silicates are hydrolized, thus : 



R 2 Si0 4 +4HOH=2K(OH) 2 +H 4 Si0 4 . 



However, according to Kahlenberg and Lincoln, the H 4 SiC\ does not dis- 

 sociate into the radicals H and Si0 4 , but forms colloidal silicic acid. 6 Thus 

 this compound is inert and the reaction reverses only to a small extent and 

 under favorable conditions, and the hydrate of the alkali metal gives an 

 alkaline reaction. 



In a similar manner hydrolysis is held to occur in water solutions of the 

 strong base sodium with the weak acid hydrosulphuric, thus: 



Na 2 S+H 2 0=NaHS+NaOH. 



Cameron further states that hydrolysis is to be expected in the case of the 

 aluminates and ferrates. "When a strong acid is united with a weak base 

 the solution gives an acid reaction, and this is also explained by dissociation, 

 the free acid supposed to result from hydrolysis being stronger than the 

 weak base/ 



Since the three most abundant acids of nature are silicic, carbonic, and 

 hydrosulphuric, all weak, hydrolysis, if true, is a reaction of fundamental 

 importance in metamorphism. 



REACTIONS. 



When, after a number of chemical substances are brought together, 

 and especially when they are united by a solvent, interactions between 

 them may occur which after a time appear to cease. When the conditions 

 have become such that there is no increase or decrease in the amount of 

 any one of the chemical compounds, the system is in a condition of 

 chemical equilibrium/ When two substances in solution, A and B, react 

 upon each other so as to produce two other substances, C and D, if 

 solutions of C and D are mixed they in turn will react upon each other to 



a Clarke, cit., pp. 740-741. 



6 Kahlenberg, L., and Lincoln, A. T., Solutions of silicates of the alkalies: Jour. Phys. Chem., vol. 

 2, 1898, pp. 77-90. 



c Cameron, cit., p. 169. 



<*Ostwald, Grundlinien, cit., pp. 276-278, 397. 



«Nernst, W., Theoretical chemistry, translated by C. S. Palmer, Macmillan & Co., London, 1895, 

 pp. 355-356. 



