]893.] Gravity of Fluid Bubbles through Liquids. 



21 



the velocity curve runs almost horizontal, showing clearly that the 

 phenomenon of turbulency is present. 



Similar curves to that for gum tragacanth were found on employ- 

 ing starch or gelatine to increase the viscosity of water. 



The case of soap is remarkable. A very slight addition of soap to 

 water produces quite a sensible increase in the velocity of the bubble. 

 The first row in Table IX gives the percentage present of a certain 

 soap solution (<> = 1'026) in mixture with water. Beneath is the 

 velocity of the air bubble in each case. Diameter of tube was 0'661. 



Table IX. Velocity through Soap Solutions. 



It so happens that at first on addition of soap a diminution of vis- 

 cosity does occur ; nevertheless the chief cause in the increase in 



