Lemon yellow is a barium chromate with a formula of BaCrO4.It decomposes in acids and also in alkalis. The pigment is rather lightfast but can change its colour to gray-green with time due to the reduction of the chromate ion to chromium 3+ ion.
Barium chromatePY 31, CI 77103
Attention: All chromates and dichromates are highly toxic chemicals and should not be used by people not trained to handle them.Barium chromate can be precipitated from the aqueous solutions of potassium chromate and barium nitrate.
The French chemist Louis Vauquelin discovered the element chrome in 1797. Shortly after the possibility of using chromates as pigments was recognized and the first methods of preparation were invented.Examples of use
To paint an autumn landscape I will not try to remember what colors suit this season, I will only be inspired by the sensation that the season gives me; the icy clearness of the sour blue sky will express the season just as well as the tonalities of the leaves. My sensation itself may vary, the autumn may be soft and warm like a protracted summer or quite cool with a cold sky and lemon yellow trees that give a chilly impression and announce winter. p. 412
Source: Henri Matisse