188G.J on Suspended Crystallisation. 



Dissimilar Bodies on Sodium Sulphate. 



5i; 



Substance in solution. 



NaaSO^.lOHoO 



Substance added. 



MgS0,.7IL0 

 NaoSeO, .." .. . 

 Na^S.Oa.oH.O . 

 Na.HP0^.ldH20 

 KC'l .. .. 

 NaCl .. .. 



KCIO3 



Nal.lH^O .. 

 Glass 



Result. 



Inactive. 



Remarks. 



Chrome Alum and Iron Alum on Common Alu3I. 



AlK(SO,)2.12HoO.. 



CrK(S0,\.12H.,0 

 FeK(SOj2-12H20 



The chrome alum solution 

 was prepared by satu- 

 rating at 70°, and then 

 allowing it to crystallise 

 in the bulb tube. 



Bodies of the same form or belonging to the same system, but not 

 similarly constituted on Alum. 



A1K(S0,)2.12H20 



NaCl (cubes) 

 FeSg (cubes) 

 Fe304 (octahedra) 



Inactive. 



Hydro-disodic Phosphate and Hydro-disodic Arsenate. 



Na2HPO,.12H20 



Na2HAsO,.12H20 



Crystullication immediate 

 and very rapid. 



When two salts which are not isomorphous are in a suj)ersaturated 

 solution together a separation of one or other of the salts may be 

 effected within certain limits. Thus in a mixture of sodium sul- 

 phate and nickel sulphate, the former may be crystallised by 

 touching with a crystal of the salt, and in allowing the mixture to 

 remain at rest for a few minutes the liquor containing the nickel 

 sulphate may be entirely poured off from the crystals of sodium 

 sulphate. 



A similar phenomenon may be seen by preparing in a long glass 

 cylinder two supersaturated solutions one above the other, the lower 

 one being sodium thiosulj)hate dissolved in its water of crystallisa- 

 tion, the upper one sodium acetate dissolved in a quarter its weight 



2 L 2 



