Gall-Stone is an animal calculus formed in the gall-bladder, principally of oxen. This concretion varies a little in colour, but is in general of a beautiful golden yellow, more powerful than gamboge, and is highly reputed as a water-colour: nevertheless, its colour is soon changed and destroyed by strong light, though not subject to alteration by impure air.

It is rarely introduced in oil painting, and is by no means eligible therein; and, as a water-colour, is better substituted by platina yellow.