melanoscope

from The Century Dictionary.

• noun An instrument devised by Lommel to distinguish between the flames of substances which in the spectroscope exhibit red bands.

from the GNU version of the Collaborative International Dictionary of English.

• noun (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.