Tertiary color if they exist at all, though indigo and scarlet are standard for blue–violet and red–vermilion. In another sense, a tertiary color is obtained by mixing secondary-colored pigments. These three colors are russet (orange–purple), slate (purple–green), and citron (green–orange), with the corresponding three quaternary colors plum (russet–slate), sage (slate–citron), buff (citron–russet) (with olive sometimes used for either slate or citron). Beyond that are shades of grey (blue grey and brown greys), which approach but never quite reach black. The RYB color terminology outlined above and in the color samples shown below is ultimately derived from the 1835 book "Chromatography", an analysis
Archer Maclean's Mercury color. However, by moving under Paint Shops, the color of the Mercury can be changed. Some doors (called filters) only allow matching-colored Mercury to pass through; some switches are also color-coded. If the Mercury is split up, the two blobs can be colored differently; if the two then merge, they form a new color. Color mixing is based on the RGB color model, as opposed to the color rules of paint. For example, a red blob and a green blob merge to form a yellow one. There are seven worlds in the game: Each world has its own theme and