Melanoscope \Me*lan"o*scope\, n. [Gr. me`las, me`lanos, black +
-scope.] (Opt.)
An instrument containing a combination of colored glasses
such that they transmit only red light, so that objects of
other colors, as green leaves, appear black when seen through
it. It is used for viewing colored flames, to detect the
presence of potassium, lithium, etc., by the red light which
they emit.
[1913 Webster]