W. F. Cooper and W. H. Nuttall 



•235 



In this method, the oil is run from a pipette through the aqueous 

 li()uid, and the number of drops formed from a definite volume of oil 

 are counted. The size of the drop and hence the drop number is 



Fi". 3. 



dependent upon (1) the interfacial tension, (2) the size of the aperture 

 of the pipette, (3) the difference in density between the oil and the 

 aqueous liquid, and (4) a constant depending upon the size of the 



