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Britannia Metal

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BRITANNIA METAL, a silvery white alloy with bluish tint, consisting essentially of tin and antimony, although copper is occasionally added. The best qualities of this alloy contain 9o% of tin and io% of antimony and may be regarded as tin hard ened by antimony. Commoner grades of the alloy may contain 94% of tin, 5% of antimony and 1% of copper. The last men tioned metal increases the ductility and decreases the fusibility of britannia metal to which, however, it gives a yellowish tint. Britannia metal is employed in the manufacture of spoons, dish covers, tea pots and other hollow ware for table use. It is easily worked into complicated shapes by spinning or stamping and can then be silver plated. An increase in the proportion of anti mony in the alloy raises the melting point, increases the hard ness and diminishes the malleability.

A brilliant lustre is imparted to articles made from britannia metal by heating them for about 3o minutes in a bath containing water (12o parts), cream of tartar (12 parts), tartar emetic (one part), hydrochloric acid (16 parts), zinc (32 parts) and powdered antimony (8 parts). When the zinc of the foregoing bath is entirely replaced by antimony, warming for varying times produces diverse shades of bluish grey, copper red, gold and bluish or violet greys.

Britannia metal containing only tin and antimony is attacked but slightly by solutions of the chlorides of ammonium, mag nesium, potassium and sodium, although aqueous caustic alkalis have a very appreciable corrosive action. ' (G. T. M.)

antimony and tin