"Rosmarine” in the Masque of Blacknesse: Jonson’s Herbal Medicamina Faciei?

AT the end of Jonson’s Masque of Blackness, the moon-goddess Ethiopia explains to the black daughters of Niger how they can achieve the blanching of their skins which they so much desire. Ultimately the metamorphosis will be accomplished by the supernatural influence of James, Britania’s own ‘sun’,
whose power exceeds even Apollo’s, for his

beams shine day and night, and are of force
To blanch an Ethiop and revive a corse.
His light sciential is, and, past mere nature,
Can salve the rude defects of every creature.
(211–14)
Before repeated exposure to James’s radiance can effect this transformation, however, they must prepare themselves over an intervening year by observing rites whose power derives not from James but from the wit and learning of Jonson. At each full moon they must
with reverence steep
[Their] bodies in that purer brine,
And wholesome dew, called rosmarine.
(299–301)
Previous editions of the masque have glossed this ‘rosmarine’ only as ‘sea-dew’, literally translating its derivation from the Latin rosmarinus (which Jonson clearly invokes in his ‘brine / And...dew’), but rosmarinus was also the Latin name for the herb rosemary.