- 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.
- What gives plants their green colour? - Literally, leaf green; a green granular matter formed
in the cells of the leaves (and other parts exposed to light) of
plants, to which they owe their green color, and through which all
ordinary assimilation of plant food takes place. Similar chlorophyll
granules have been found in the tissues of the lower animals.