<P> The drop is an approximated unit of measure of volume, the amount dispensed as one drop from a dropper or drip chamber . It is often used in giving quantities of liquid drugs to patients, and occasionally in cooking . </P> <P> The volume of a drop is not well defined: it depends on the device and technique used to produce the drop, on the strength of the gravitational field, and on the viscosity, density and the surface tension of the liquid . </P> <P> There are several exact definitions of a "drop": </P>

How many ml is a drop of water
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