1 Used other than as an idiom: see outer ,â core. ( 2 planetology) The hot liquid material found near the centre of some planets, distinct from the solid inner core. ( 3 geology) The part of the Earth between the mantle and inner core, responsible for generating the planet's magnetic field. 4  Link/Cite.
Differential Staining is a staining process which uses more than one chemical stain. Using multiple stains can better differentiate between different microorganisms or structures/cellular components of a single organism.
The Gram stain is a differential stain: if the cell wall is exterior to the plasma membrane, the bacteria turn purple (the cell wall retains the blue-violet stain crystal violet), and the membranes retain safranin, a red-pink stain. This produces a royal purple color.