Play of color

Labrador-isieren, n. play of colors (as on lab-radorite), iridescence, -stein, m. Labrador stone, labradorite. 

Schilf-glascrz, n. freieslebenite. -rohr, n. reed. Schiller, m. play of colors, iridescence surface color, metallic color, schiller. -farbe, /. changeable color schiller color, surface color, metallic color. 

Strychnine.—Treat 0.5 gm. of brucine with 5 gm. of absolute alcohol at the ordinary temperature for one hour, with frequent shaking. Filter, transfer a portion of the undissolved substance to a watch glass, allow it to dry thereon, and then dissolve it in a few drops of concentrated sulphuric acid. To this solution add a small crystal of potassium dichromate. A play of colors, from blue through violet and. red into green, is evidence of the presence of strychnine. 

Play of color is the term used to describe the internal spectral colors that appear inside some specimens of materials like opal and some synthetics. The colors seem to move when the specimen is turned or the light source is moved. Labradorescence is a broad play of colors common in labradorite and other minerals (mostly feldspars) having polysynthetic twinning. 

Opalescence is a pearly or milky internal reflection, most common in white or light-colored minerals such as some opal or moonstone (albite or ortho-clase feldspar). This is also known as adularescence. Like iridescence and play of color, these properties are not consistent within any natural material, and can only be used to describe individual specimens. Some synthetic materials have been created specifically to display these properties and so always show them. 

Opal is a common mineral in chemical sediments, as deposits around hot springs, replacing fossils such as wood, or as secondary vein-filling. Most opal is common opal, without the internal play of colors that makes some opal precious. Common opal is usually light colored, and has a distinctive waxy luster. 

Polarization cross very distinct beautiful play of colors with selenite plate. 

Polarization cross distinct but no marked play of color with selenite plate. 

The chemist cannot of course come anywhere near to creating such a wonderlul coinposiuon in blue and gold as produced by nature or by this great artist, but he can remind us of this imposing play of colors wdth the help of a simple redox reaction. 

A dilute solution of potassium dichromate forms a yellow, crystalline ppt. in strychnine solutions which, when washed and heated with concentrated H. 80, gives the play of colors indicated in 2. 

Figure 3. Left A jet of tap water on a superhydrophobic glass slide. Interference at the air layer trapped underneath the water results in an intricate play of colors. Right A superhydrophobic glass slide in water after 27 days of immersion. The thin, homogeneous air layer leads to total reflectance of light.

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