SIMPLE COLOURS.
The vision can separate six monochromatic colours from a beam of white light, therefore in practical work six must be dealt with, no matter how they may be theoretically accounted for. They naturally take the accepted spectrum names and symbols already in use. To these are added two other terms, Bk. to signify black, and L. for light; these terms deal with the brightness, or dinginess, of a colour.
| Simple Terms. | Symbols. |
| Red | R |
| Orange | O |
| Yellow | Y |
| Green | G |
| Blue | B |
| Violet | V |
| Black | Bk |
| White | L |