Yes, but if a drop of Vetiver were always twice the mass of a drop of lavendar then the measurement by drops would be reproducible. The problem is that the viscosity of different batches of the same EO, say vetiver, may vary which would produce inconsistency in the mass of a drop. Dissolving the EOs in alcohol though will tend to greatly lessen any variability in viscosity between batches of the same EO.[/QUOTE]
I found indispensable to have a balance which weights the thousandth of gram.
When I have ultimated a composition by drops, I reproduce it multiplicating the drops by ten times and mesuring the weicht of each component.
In this way I do have a pretty precise formula that I can reproduce by weight in any quantity.