METALS. 109 



stirring, so as to free it from icopurities, as carbon, silica, 

 etc. 



Reduc'tion. — The operation of separating a metal from other 

 substances with which it is combined. 



Refin'ing. — A process whereby the substances acted upon are 

 puritied by the chemical separation of dross and impuri- 

 ties, and of such foreign matters as may be in combination 

 with them. 



Eoast'ing". — The protracted application of heat, below a fusing- 

 point, to metallic ores. 



Sco'riae. — The dross of metals in fusion. 



Smelting. — The operation of melting ores for the purpose of 

 extracting the metal. 



Torrefac'tion. — The operation of roasting ores. 



Toss'ing. — A process which consists in suspending ores by vio- 

 lent agitation in water, in order to separate the lighter or 

 earthy particles. 



Ustula'tion, — The operation of expelling one substance from 

 another by heat, as sulphur and arsenic from ores, in a 

 niuifle. 



METALS. 



Founding'. — The art of casting or forming of melted metal 

 any article according to a given design or pattern. 



Lacq'uering. — The art of covering metals loith lacquer. 



Metalloch'romy (G-r. mefnUon, a metal, and chroma, a color). 

 — The art of coloring metals. 



Metallog'raphy (Gr. metallon, metal, and graplie, descrip- 

 tion). — An account of metals, or a treatise on metallic 

 substances. 



Met'allurgy. — See Metallurgy. 



Metals have been divided by Prof lloscoe into eleven classes, 

 which are as follows : 



ALKALIES. 



1. Potas'siiim. — The metallic base of pure potash. It is 

 ligliter than water, and of a silver-white color. 



2. So'dium. — The metallic base of soda. It is white, 

 opaque, and has the lustre and general appearance of 

 silver. 



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