270 VII. EARTHS AND ALKALIES— 



Rat's stone, Witherite Terra ponderosa, Carhonas harytce. 

 Found in mines; used as a poison for rats, and to prepare 

 muriate of barjtes. 



Kemp's wmri^, Predpitafed carbonate of harytes. Witherite 

 q. p., spirit of salt q. s., dissolve, add subcarbonate of ammonia 

 to precipitate the white, wash, and dry in cakes for use. 



MoRvEAu's WHITE. Dissolve cream of tartar in water, and 

 add lime-water as long as any sediment falls, wash and dry. 



Zaffre, Safflor, Saffra. One part of roasted cobalt, ground 

 with two or three parts of very pure quartzose sand ; used as a 

 blue colour for painting glass ; from Saxony. 



Smalt, Powder blue, Smalta, Azurum. From roasted cobalt, 

 melted with twice or thrice its weight of sand, and an equal 

 weight of potash ; used in painting, and getting up linen : from 

 Saxony. 



Ultra-marine blue, Cceruleum ultramontanum. Lapis lazuli 

 lib. is heated to redness, quenched in water, and ground to a fine 

 powder ; to this is added yellow rosin 6 oz., turpentine, bees'* wax, 

 linseed oil, ana 2 oz., previously melted together, and the whole 

 made into a mass ; this is kneaded in successive portions of warm 

 water, which it colours blue, and from whence it is deposited by 

 standing, and sorted according to its qualities : a fine blue colour 

 with poppy oil ; East Indian Tapis lazuli. 



Ultramarine ashes, Sander"* s blue. The remains left after 

 the extraction of ultramarine, the wax and oil being burned away, 

 and the ashes washed ; inferior in colour. 



Egyptian azure. Carbonate of soda 15 oz., calcined flints 

 20 oz., copper filings 3oz., mix and heat together for two hours: 

 a fine sky blue. 



Fluxes for enamel colours. Flint powder 4 oz., flint glass 

 12 oz., red lead 16 oz., calcined borax 3 oz. Melt in a Hessian 

 crucible ; keep it melted for several hours in a steady heat, then 

 pour it out into water, and grind it in a white biscuit-ware 

 mortar. 



2. Flint glass 10 oz., white arsenic and nitre, of each 1 oz. 



3. Flint glass 3 oz., red lead 1 oz. 



4. Flint glass 16 oz., red lead 19 oz., borax (not calcined) 1 1 oz. 



5. Flint glass 6 oz., red lead 8 oz., flux. No. 2, 4 oz. 



Yellow enamel. Red lead 8oz., oxide of antimony 1 oz., 

 oxide of tin 1 oz., calcined together ; of this take 2 oz., flux. No. 4, 

 3oz. 



Orange enamel. Red lead 12 oz., red sulphate of iron 1 oz., 



