What does "alchemy" mean?

Alchemy: A mixed metal composed mainly of brass, formerly used for various utensils; hence, a trumpet. [Obs.] Put to their mouths the sounding alchemy. Milton.

Additional senses

  1. 2.Miraculous power of transmuting something common into something precious. Kissing with golden face the meadows green, Gilding pale streams with heavenly alchemy. Shak.

Sources