=The Colouring Matter of Saffron.=—The dried stigma of the flowers of the saffron, a species of _iris_, has been long used for colouring foods. It contains a very handsome yellow colouring matter of a characteristic shade; formerly this was largely used in silk-dyeing, and especially for dyeing glove leather. It is practically now no longer used; considerably cheaper aniline dyes produce an equally good shade. On account of its high price (1 kilogramme of saffron contains about 60,000 stigmata) this material cannot be used for lakes, although they leave nothing to be desired in fineness of shade, but they have no great permanence. =The Colouring Matter of Gardenia Grandiflora.=—The fruits of this plant, which are imported from Southern Asia, contain a beautiful dark yellow colouring matter, which, according to Rochleder, is identical with the colouring matter of saffron. It is readily soluble in water; lakes of various shades can readily be obtained by the addition of salts to the aqueous solution. Alum gives a pure yellow, lead acetate a yellowish red, and stannous chloride a dark orange red lake. CHAPTER L. RED LAKES. COCHINEAL AND CARMINE. The purple of the ancients was obtained from the shellfish _purpura_; it was so costly that it was regarded as an attribute of royalty. According to history the Tyrians discovered this colour; at any rate they were able to use it for dyeing. In the writings of the ancients Tyrian purple garments were regarded as the greatest luxury. The art of obtaining a purple from this source was lost; more recently it has been re-discovered, but the colour is found in no way to correspond with what we regard as a bright shade. When the Spaniards conquered Mexico they found an insect cultivated which produced a splendid red colouring matter. This insect, the cochineal, is parasitic upon certain cacti, especially _Cactus coccinellifer_ and _Cactus opuntia_. The females only are used as colouring material; the males are very small, and much fewer in number. The cultivation of the proper species of cactus and of the cochineal has spread to most tropical countries. The females, which are attached in enormous numbers, are brushed off and killed by heating upon hot plates. They then appear as grains of the size of millet seeds, with a wrinkled surface covered with a silvery grey dust. This variety of cochineal is the best. Black cochineal also comes into commerce; it has a brownish black colour. It is produced by killing the insects in boiling water, by which the grey dust which covers the living insect is removed. Cochineal produces when ground an ugly reddish brown powder.