434 Prof. J. J. Thomson and Mr. H. F. Newall. [Dec. 17, 



of carbonate of soda dropped into paraffin oil. The phases are repre- 

 sented in fig. 12. The earlier ones are somewhat similar to those 

 above described. But the phase shown at e is different. Here it 

 seems quite a chance, as it were, that the disk does not break into a 

 ring. The instability is immediately shown by the oscillations, which 

 begin at this point and continue in a regular manner through a fall 

 of more than 3 feet. An attempt is made to show this in the 

 phases £, tj, 6. A thickening appears at one side, and the opposite 

 «dge thins off considerably, and these irregularities travel regularly 

 round the drop as it falls through the column. 



Effect of the Height of Fall on the Formation of the Ring. 



We have found that alteration of the height from which a drop falls 

 before reaching the surface of the column modifies the formation of 



Fia. 12. 



the rings considerably. Good rings are formed only within small 

 limits of height — from about 1 to 3 inches, according to the size of the 

 drop. Above 3 inches it is only when the drop falls back into the 

 column after rebound that a ring is formed, and that very irregularly. 

 But within the limits for any particular size of drop rings are much 



