612 



Professor Thomson 



[May 14, 



the bulb is lowered into the liquid contained in the flask and allowed 

 to remain there for some time to show that the disturbance produced 

 by its introduction into the fluid does not excite crystallisation. The 

 bulb is finally lightly brokeu under the fluid and the result observed. 

 Bulbs also containing water, pieces of washed glass, &c., may be 

 broken under the supersaturated solutions, to show that the dis- 

 ruption produced on breaking does not excite crystallisation. 



A second method which may be employed for the introduction 

 of nuclei is that introduced by Professor Liversidge.* This consists 

 of a siphon tube, in which crystallisation is induced in the first 

 limb and allowed gradually to pass over the bend and down to the 

 point of the second limb. 



The following table gives the results of many experiments on 

 the action of isomorphous and also of dissimilar substances on 

 supersaturated solutions of each other. 



Dissimilar Bodies on Magnesium Sulphate. 



MgSO,.7H20 



MgK.(SO,).,.6H..O 

 Na.,SO..10HoO .. 

 Na:S,03.5H;0 .. 



NaCr 



Glass 



Inactive. 



Isomorphous Salts on Sodium Sulphate. 



Na2SO,.10II.O 



Na.,SeO4.10H.,O .. 

 NaJCrO^.lOH^O .. 



Active .. 



Crystallisation immediate. 



* Proc. Hoy. Soc, xx. 497. 



