The Italians employ frequently the cocoons of the silkworm for this purpose; these take a brilliant dye, preserve their colour, and possess a transparent velvety appearance, suitable for petals. Of late years, the French have adopted the finest cambric for making petals, and the taffeta of Florence for the leaves. M. de Bernardière employs whalebone in very thin leaves for artificial flowers; and by bleaching and dyeing them of various hues, he has succeeded in making his imitations of nature to be very remarkable.
The colouring matters used in flower dyeing are the following:—
For red; carmine dissolved in a solution of salt of tartar.
For blue; indigo dissolved in sulphuric acid, diluted and neutralized in part by Spanish whitening.
For bright yellow; a solution of turmeric in spirit of wine. Cream of tartar brightens all these colours.
For violet; archil, and a blue bath.
For lilac; archil.
Some petals are made of velvet, and are coloured merely by the application of the finger dipped in the dye.
FLUATES, more properly fluorides (Eng. and Fr.; Flusssäure, Germ.); compounds of fluorine and the metals; as fluor spar, for example, which consists of fluorine and calcium.
FLUOR SPAR. (Chaux fluatée, Fr.; Spath fluor, Germ.) This mineral often exhibits a variety of vivid colours. It crystallizes in the cubic system; with regular octahedral and tetrahedral cleavages; spec. grav. 3·1 to 3·2; scratches calc spar, but is scratched by a steel point; usually phosphorescent with heat; fusible at the blowpipe into an opaque bead; acted on by the acids, with disengagement of a vapour which corrodes glass; its solution affords precipitates with the oxalates, but not with ammonia. Its constituents are, fluorine, 48·13; calcium, 51·87 in 100.