Blue, Queen’s. See Thumb-blue (below).
Blue, San′der’s. Ultramarine-ashes.
Blue, Sax′on. Saxon Az′ure. A compound of hydrate of alumina and Prussian blue, prepared as follows:—
1. To sulphate of iron, 1 oz.; and alum, 8 oz.; dissolved in water, 1 gall.; add, simultaneously, separate solutions of prussiate of potash and common pearlash, until they cease to produce a precipitate; after repose collect the deposit, wash it well with water, and dry it.
2. A solution of sulphate of iron is precipitated with another of prussiate of potash, and instantly mixed with the precipitate which has just been obtained by treating a solution of alum with a solution of pearlash; the mixed precipitates being finally treated as before.
Smalts (which see; also China-blue and Egyptian Azure, above).
Blue, Thénard’s. See Ultramarine (Cobaltic).
Blue, Thumb′. Cake′-blue, Crown′-blue, Fig′-blue, Knob′-blue, Mech′lenburg-blue, (mēk′-), Queen’s-blue, Stone-blue, &c. Names given to the lump-blue used in laundries, which vary according to the quality and the particular form given to it.
Prep. 1. A mixture of powdered starch with sufficient indigo (in impalpable powder) to give the necessary colour, made into a stiff dough with starch-paste, and then formed into lumps or cakes of the desired size and shape, and dried. This forms the ordinary ‘washerwoman’s blue’ of the shops.
2. As the last, but substituting cæruleo-sulphate of potassa or blue carmine[226] for the ‘powdered indigo’ ordered in the last formula. Very fine.