I have just started learning salt analysis in inorganic chemistry. In it i came across the names of colors of various precipitates and solutions. Why do they have prefixes such as "scarlet" in "scarlet red"? Why does it need to be called "red litharge" and not just "red", "Prussian blue" and not just "blue", "crimson yellow" and not just "yellow", "apple green" and not just "green"?

I wanted to know if there are any rules for naming such colors, or they are just named randomly.

  • 5
    $\begingroup$ 1. Crimson yellow is something I don't think exists. And it's Prussian blue, not Persian blue. Properly phrased questions are more favourably seen. 2. This is a trivial question of how colours are designated, and does not have anything to do with actual chemistry. 3. Colour is not something scientific that should have a systematic nomenclature. Since many compounds appear red, making it a bit more specific as to which shade of red it is, helps, specially while reporting the experiment. It all depends on what shade you see in the test tube. There's no systematic naming. $\endgroup$
    – TRC
    Aug 1 at 14:08
  • $\begingroup$ @TRC Persian blue is also a color but most likely the author meant Prussian. $\endgroup$
    – M. Farooq
    Aug 1 at 15:48
  • 1
    $\begingroup$ They are just descriptors. Unless one is affected by color vision problems, the typical examples in text books have been observed so many times to be reliable. Then what is pale yellow can be different between you and me.... But I don't understand the questions really. It is not really different in normal day life. An accurate description of "colours" is something else, as said in other comments and answers. $\endgroup$
    – Alchimista
    Aug 2 at 11:08
  • $\begingroup$ There are many shades of "red", so for specificity, prefix are used. "Scarlet-red" sound very specific. $\endgroup$ Aug 3 at 2:47

It is an awful practice to describe the colors of precipitates with object-colors, like apple green, strawberry red, olive green, etc. I have seen these weird descriptions of hydrogen lines in its spectrum in first-year lab reports. You will not encounter this language in professional work. Avoid such usage while writing lab reports.

You can undoubtedly use simpler expressions without using an object like an apple or a strawberry, e.g., deep blue, bright yellow type expressions. There is no hard and fast rule as stated in the comments.

If you were to discover a new precipitate whose color is hard to describe, then a picture is worth a thousand words for a formal report (assuming the camera won't distort the colors).

Those who work in the textile industry and deal with fancy dyes use more sophisticated instruments to "describe" color. Color measurement science is a whole field of science, and there you do not need the crutches of such words. See, for example, this essay on Wikipedia Colorimetry

  • 1
    $\begingroup$ +1 For the hint to just take a photo, which in some publications became part of the documentation (e.g., on OrganicSynthesis, example, instructions to the authors revised in 2019). And put a reference for scale and color next to your object of interest, too, the cap of your ball pen isn't the best yet better than nothing (because it is standardized) since cameras capture withe and colors differently in daylight/flashlight, etc. $\endgroup$
    – Buttonwood
    Aug 1 at 16:26
  • 3
    $\begingroup$ This goes too far. If I see apple green I note in my lab journal apple green. All the rest is true. But has nothing to do with the actual question. If my crude is olive, that is the best description. Just we know that is the pictorial description of a single operator. To make a wise use of that is up to us reading that journal. $\endgroup$
    – Alchimista
    Aug 2 at 11:01

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