YELLOWS
The base of most fine yellows is picric acid. The chromates of zinc and baryta give very permanent yellows, which are particularly useful in mixing greens.
The vegetable yellows are less durable. They include turmeric, which is especially fugitive, and quercitron; the former is turned red, and the latter brown, by the action of hydrochloric acid.
Orange tints are easily obtained by using red over yellow, first allowing the yellow to dry completely; or they can be bought ready prepared with alizarin. Mandarine and nasturtium tints can also be bought ready prepared, or may be made by a mixture of vegetable colour, such as saffron and arnotto.
14. Embossed and punched brown calf binding. Rubáiyát of Omar Khayyám. Designed by Mary G. Houston. Modern English.
BLUES
Good and durable blues are obtained from indigo and alizarin.