a Sphere in a Viscous Fluid. 329 



oscillation. When two small bubbles come into contact during 

 their ascent they sometimes rebound as if they were elastic 

 spheres, and at other times coalesce to form a larger bubble. 

 It is a common thing to see two bubbles of the same size 

 ascending together, at a distance apart perhaps ten times 

 the diameter of either, with the line joining their centres 

 making an angle of 45° with the vertical. 



Fig. 1. 

 Z-S cm 



Jl 



^"7 



2L 



<r 



■\tfh.cnv 



"> 36. cnv 







■36. cm 



>.2QScm 



PRESSURE 

 TUBE. 



EXIT TUBE 

 RETORT STAND 



A. 



The behaviour of the different capillary tubes used pre- 

 sented some interesting features. With thick-walled tubes 

 the bubbles produced were of practically the same size for 

 any particular tube. 



With very tine thin-walled capillaries the size of the bubble 



