ARTICLES 233 



Capillary tubes having very sharp edges are used, and two tubes 

 of different radii are attached to vertical rods so that they can 

 be moved up and down a vertical scale. The two tubes are 

 attached to the same air reservoir, and the heights are adjusted 

 until bubbles slowly detach themselves from both tubes simul- 

 taneously ; then 



r —r 



and the actual value of the pressure is not required. Since 



TjT" = d'h'ld''h" 



the method is very convenient for determining relative sur- 

 face tensions. 



References to Surface Tension Methods 



Morgan (/. Amer. Chem. Soc, vols, xxx, xxxiii, xxxv, xxxvii). 



Ferguson {Phil. Mag., 1912-14), Pull on Disc, etc. 



Langmuir (/. Amer. Chem. Soc, vol. xxxiii, No. 9), Films on the Surface of 



Water. 

 Lenard {Wied. Ann., vol. xxx, p. 209), Oscillations of Drops. 

 WoRTHiNGTON {Phil. Mag., p. 43, 1885), Pull on a Vertical Plate (Wilhelmy). 

 Rayleigh {Phil. Mag., vol. xxx, p. 386), Ripples. 

 Magie {Phil. Mag., 1888), Height of Bubbles and Drops. 

 Bohr {Phil. Trans., A, p. 209, 1909), Waves on a Jet. 

 TiMBERG {Weid. Ann., vol. xxx, p. 545), Pull on a Ring. 

 Cantor {Weid. Ann., vol. xlvii, p. 399), Pull on a Ring. 

 Hall {Phil. Mag., 1893), Tension in a Film. 

 Ramsay and Shields {Phil. Trans., A, p. 647), Capillary Rise. 

 Sentis {Jour, de Phys., 1887-97), Combined Capillary Tube and Radius of 

 Drop Method. 



