What are the factors on the volume of a drop? Earlier today I grabbed a flask of sweetener and reading through the nutrition info I found this "Approximately 0.2cal per 0.2mL or drop". So I started thinking, what affects the volume of a drop? Is it altered on the surface it is dripping from, the viscosity or the density of the liquid itself, by the gas/mean it is immersed into? 
What are the most important factors that alter the drop-volume relation?
 A: The size of drops of a Newtonian liquid ejected from an aperture in a laminar regime without simultaneous air intake at that aperture are governed by two non-dimensional numbers, that combine the inertial forces, viscous forces and capillary forces (which have different dependences on the length scale, i.e. size of aperture). There are several ways to combine them, but usual choices are the Reynolds and Ohnesorge numbers. 
The geometry of the outlet can also change things, though, since it will affect the velocity profile. At small scales or large speeds the air flow can also be important. So on the whole there's very little universality in drop size! You should be able to obtain quite different ones with the same liquid if you can attain different speeds of ejection, or if you change the way you produce them.
This complexity makes it difficult to point an article in particular as we have rather a negative result here: no universality. You can check Jens Eggers' 2005 review in ZAMP, many of his other papers on drops can give you examples of drop formation: http://www2.maths.bris.ac.uk/~majge/
