The „Peri Chromaton“ (On Colours) is a treatise about colours and their formation, and about their different appearance in objects, plants and animals. This small text has been handed down among the opera of the „Corpus Aristotelicum“ but its attribution to Aristotle has been found controverisal in the modern era, because of its intrinsic incongruity with Aristotelian theories and the Aristotelian writing style.
The book has been divided in 6 different chapters, with the following contents:
1.Ch: Primary colours are the colours which belong to the
elements. Air and water are naturally white, fire and the sun yellow. Earth
is naturally white but usually contains liquids which dye it various colours;
when these liquids are burned out, it becomes white or nearly white, as can
be seen in the case of ash or lye-mixture.
Black is the colour of elements in the process of transmutation. Other colours
are derived from a mixture of these. Darkness is due to the failure of light.
The appearance of black can arise in three ways. (1) Things appear
black if they are not seen at all, i.e if they reflect no light to the eye, though
the space surrounding them is visible.
Things from which little light is reflected appear black, e.g.
shadows and rough water, because it does not reflect the light evenly. Clouds
and masses of air or water too dense for the light to penetrate appear black
because the light-rays they reflect are „rare“; the areas from which
no light is reflected remain dark.
Other colours are the result of a mixture of simple colours.
2.Ch: Mixture and multiplicity of colours. Secondary colours. Examination and investigation method.
3.Ch: Origin of the unlimited multiplicity of colours; no colour can be observed purely.
4.Ch: Dyeing process
5.Ch:The colour of plants depends on their liquid element and on their temperament. To broil them by means of heat generates their change of hue, which is then absorbed and held back by different parts.
6.Ch:The colour of animals. Same principle as for plants.